key: cord-0030933-4tndcap4
authors: nan
title: ESPR 2022
date: 2022-05-04
journal: Pediatr Radiol
DOI: 10.1007/s00247-022-05370-2
sha: 4b6827f16ed69cc1610081cfacd0a40d224e89c8
doc_id: 30933
cord_uid: 4tndcap4

nan

Professor Adamsbaum is an outstanding medical practitioner in all the spectra of Paediatric Radiology, with a special interest in Neuroradiology, Fetal imaging and Musculoskeletal Radiology, and she is recognized as a world leader in the Radiology of Child abuse. She is a gifted teacher, transmitting smoothly her in-depth knowledge, with her special French charm, and she ranks internationally as one of the best teachers in Paediatric Radiology. Professor Adamsbaum is very active in research in Paediatric Radiology and has published over 250 scientific papers and several books. Our national and international Catherine is "Une Grande Dame de la Radiopediatrie", but above all she is one of the species, rare nowadays, of genuine dignified gentility. Our Catherine enjoys life; she adores travelling, singing, dancing and being in company of her many friends. She is a wonderful wife to Olivier, a devoted mother to her children Thomas, Léo, Benjamin and Nathan, a sweet grand'mere to Siwa, and a great loyal friend. Prof. Maria I Argyropoulou, February 2020 Prof. Chateil has been member of the board of College of Professors of Radiology in France for many years, leading radiation protection education and the annual evaluation of residents. He has valiantly served the European Society of Radiology as a member since 2001, as a paediatric radiology subcommittee member and chairman of the paediatric radiology subcommittee in ECR 2011. Jean Francois attended his first ESPR congress in Montreux in 1988 and became a member of ESPR in 1994, proposed by Fred Avni and Gabriel Kalifa. Since that time, he has attended more than twenty ESPR and IPR meetings, hosting the unforgettable Bordeaux 2010 annual post graduate course and ESPR Congress, which he organized and chaired. He has worked extensively for this Society on many high profile, very demanding tasks, including renewal and rebuilding of the ESPR website in 2005, as webmaster of the 2006 new website, together with Prof. Rick van Rijn. He was responsible for writing the paediatric portion of the European training Curriculum of Radiology for Residents (levels I and II) and post-graduate (level III), and is currently active in the creation and completion of the first cycle of the European Diploma in Paediatric Radiology (EDiPR). He has been a respected member of the ESPR board from which he stepped down in 2015. Prof. JF Chateil has served paediatric radiology within ESR as a member for the organisation of the European Diploma in Radiology, initially as delegate of ESPR for paediatric radiology , then as reviewer for the written part of the examination (2017-19). Prof. JF Chateil is a highly distinguished academic radiologist with more than 130 referenced articles in PubMed and more than 70 books chapters.

He is an international celebrity as a speaker, with multiple lectures and presentations at numerous high profile national and international congresses in paediatric radiology and paediatric neuroradiology within Europe and as a selected ambassador of his craft in Outreach scientific activities in Tunisia, Algeria, Lebanon, Syria, Cambodia and Vietnam. He has been a reviewer and collaborator for many different national and international medical journals and an inspirational mentor, training young doctors, giving opportunities to his peers at a local, national and international level, with his perspicacious vision, hard work and by undertaking paediatric radiology education and research projects. Jean Francois greatly values his family and friends, and is a talented sportsman, a sailor in l'Ile de Ré, a keen photographer, a voyager, and a jazz aficionado. His family and friends are a continuous source of inspiration to him. For all of his hard work and dedication in contributing to the care of children and for his exceptional dedication and commitment to the Society over many years during a distinguished career, it is a pleasure to award him honorary membership of our Society. Reverse radiology : diagnosis of skeletal dysplasias in the era of whole exome sequencing, artificial intelligence and drug trials.

Amaka C Offiah is Professor in Paediatric Musculoskeletal Imaging and consultant paediatric radiologist at the University of Sheffield and Sheffield Children's NHS Foundation Trust, UK. She is Chair of the ESPR Child Abuse Taskforce and has published widely, been involved in the development of national guidelines and published a textbook related to investigating suspected physical abuse in children. Professor Offiah is the first BAME and first female Managing Editor of the journal Pediatric Radiology. Purpose: To assess utility of Shear wave elastography (SWE) in steroid resistant nephrotic syndrome (SRNS) and steroid sensitive nephrotic syndrome (SSNS) cases of children. Material and methods: In this cross-sectional study, renal stiffness was measured in 83 children aged 4-14 years with SRNS (40 children) and SSNS (43 children) visiting a tertiary care centre in India. Mean values were recorded, one each in the upper, mid, and lower pole of bilateral kidneys in all the children. These values were then statistically analyzed and comparison was made between two groups. Results: There were 83 children included in the study in which mean age was 7.08 ± 2.75 years (Mean ± SD). In the SRNS group of 40 children, 67.5% (27) were males and 32.5% (13) were females while mean and median age in these children were 7.50 ± 2.81 and 7.00 years respectively. While in the SSNS group of 43 children, 72.1 % (31) were males and 27.9% (12) were females while mean and median age in these children were 6.70 ± 2.67 and 6.00 years respectively. Evaluation of SWE values revealed that mean and median values were 14.92 ± 7.58 kPa and 12.13 kPa respectively in SRNS group, while in SSNS group mean and median values were 11.18 ± 4.11 kPa and 10.00 kPa respectively. The difference between the mean values of the parenchymal stiffness in kidneys between SRNS and SSNS groups was statistically significant (p=0.027). The area under the receiver operating characteristic curve for SWE value in SRNS vs. SSNS was 0.641 (95% CI-0.519-0.764). The corresponding cutoff value was 11.26 with 62.5 % sensitivity and 69.8 % specificity. Conclusion: SWE values of the kidneys in children with SRNS is higher than that of children with SSNS. The SWE values of the kidneys may help in early diagnosis and categorization of children into steroid resistant and steroid sensitive nephrotic syndrome.

Eoghan Laffan 1 , Angela T Byrne 1 , Clare Brenner 1 , Heba Elbaaly 1 , Eimear Joyce 1 , David Rea 1 , Aisling Snow 1 1. CHI at Crumlin, Dublin, Ireland

Purpose: On May 14 th 2020, the Irish healthcare system underwent a cyber attack by ransomware, resulting in the complete shutdown of all IT healthcare infrastructure for 18 days. IT systems in all hospitals in the country were shut down. This included a national PACS service, resulting in an inability to digitally report imaging via the hospital intranet, or retrieve and review any archived imaging. This presentation will review the challenges faced by a single Paediatric Radiology department and the various solutions used to maintain an acute and urgent care imaging service. Materials and Methods: The initial days focussed on the department's ability to minimise risk, while maintaining an acute Radiology service, including handwritten Radiology reporting and image viewing for critical departments (Emergency, ICU). A makeshift solution for the hospital was found, using multiple, newly purchased PCs (iMac®, Cupertino, CA, USA), USB sticks and a free, open source DICOM image viewer (Horos??). These PCs were installed where review of imaging was deemed essential (e.g. Radiology department, ICU, Emergency, operating theatre, OPD). Radiographs performed in critical areas (ICU, ED) were exported from mobile units onto USBs and then imported onto PCs by Radiographers several times a day. No prior imaging was available for review. Results: Acute Radiology services were maintained throughout. Report turnaround time was less than 1 hour with handwritten reports, each report copied and a backup stored. After the initial, major disruption, elective imaging was resumed and maintained, with examination numbers broadly similar to previous years. Once PACS was brought back online, a significant backlog of work commenced, importing all imaging performed during the downtime period. All studies were re-reported digitally, compared with previous imaging and any discrepancies noted. Conclusion: This is one department's experience of a recent, catastrophic cyber attack on a national IT healthcare system, including PACS. All Radiology departments and institutions should prepare for similar attacks in the future. They should run simulations and consider developing departmental preparedness guidelines, to ensure the smallest disruption to service possible and minimise risk to patients and staff. Purpose: MYCN amplification (MNA) represents an important prognostic factor in neuroblastoma (NB) staging, associated with poor outcomes. Radiomics derived data has been shown to predict specific gene expression patterns in different tumours, methodology known as Radiogenomics. The aim of the present study was to evaluate the feasibility of CT based radiomics and radiogenomics analysis in NB pediatric patients, and its performance in predicting MNA expression of NB from standard staging CT scans. Material and Methods: The available staging CT imaging data was retrieved from the institutional Picture Archiving and Communication System (PACS) of two institutions and anonymized. All images were reviewed by two paediatric radiologists blinded for the MNA status. The imaged features of the tumours were analysed and categorized for classical imaging features and tumour segmentation of the region of interest (ROI) was manually delineated on five of the largest representative cross-sectional

images. An open-source package Pyradiomics was used to extract 650 features from 2D ROI on the CT slices. Random forest (RF) was used to classify MNA status using radiomic features extracted from CT slices. Data was randomly split into a training set (80%) and a test set (20%).

The study included 46 patients diagnosed with NB. MNA was confirmed in 16 patients (34.8%) The performance of the prediction model was evaluated by calculation of the area under the curve (AUC). An AUC of 0.85 was obtained for the study of the cases with contrast in the CT exam. The addition of the cases without contrast on the CT exam seems to introduce heterogeneity on the data that degrades the performance of the learning model, with an AUC of 0.69. The predictive model developed showed that radiomic features have useful information to classify the MYCN amplification status, confirming that this methodology could be helpful to extract genomic information in a non-invasively way, contributing for risk stratification in neuroblastoma patients. Furthermore, the results obtained showed that information from radiomic features extracted from 2D ROI of CT images allows obtaining relevant information for MYCN characterization, even when CT scans are performed in various scanners at different institutions, thus facilitating its integration in future clinical practice.

Luis Octavio Tierradentro-García 1 , Joseph Stern 1 , Alireza Zandifar 1 , Jorge Du Ub Kim 1 , Jean Henri Nel 1 , Savvas Andronikou 1 1. Children's Hospital of Philadelphia, Philadelphia, PA, United States Purpose: Children on vigabatrin therapy may develop vigabatrin-related (VR) MRI abnormalities. We aimed to characterize the MRI findings of VR-toxicity in children and determine their reversibility on follow-up MRI. Materials and Methods: We evaluated MRI performed on children undergoing vigabatrin therapy for seizures, as well as any MRI performed prior to initiation, and after discontinuation of vigabatrin. A pediatric neuroradiologist with >20 years' experience, blinded to the timing of MRI, assessed T2/FLAIR and DWI sequences for hyperintensities and/ or restricted diffusion in the following: globus pallidi (GP), thalami (Th), midbrain (Mi), pons (P), medulla (Me), dentate nuclei (DN), hippocampi (Hi), subthalamic nuclei (SN), central tegmental tracts (CTT), anterior commissure (AC), and hypothalami (Hy). Frequency and reversibility of VR lesions were determined. Results: 18 children (median age 288(IQR173-461) days at initiation of vigabatrin; 50% girls) had 43 scans: 13 (72%) prior to initiation (none demonstrating abnormality) and 12 (67%) after discontinuation of vigabatrin. Most lesions on T2/FLAIR during treatment occurred in the GP (n=15; 83%), Th (n=15; 83%), and Mi (n=14; 78%). No MRI had an abnormality in all locations simultaneously. One patient had T2/FLAIR abnormalities in all structures except the Hi. Correspondingly, the most common locations for restricted diffusion were the GP (n=14; 78%), Th (n=14; 78%), and SN (n=14; 78%); one patient had restricted diffusion in all structures except DN. Post-vigabatrin discontinuation, 78% (n=14) had complete resolution of T2/FLAIR abnormalities, and all children had at least partial resolution. Complete resolution on T2/FLAIR in all patients was seen at 4/11 locations: Mi, DN, SN, and Hy. Complete resolution of restricted diffusion was observed in 6/11 locations: GP, Mi, DN, Hi, AC, and Hy. Conclusions: Although the globus pallidi and thalami are most commonly affected in VR-toxicity, there are other characteristic regions involved, such as the subthalamic nuclei. Most VR neuroimaging findings are reversible. DWI did not show particular advantage for detection but may offer physiologic information for future management. Further prospective research is recommended to establish a longitudinal timeline of VR-lesion development and resolution on MRI.

Objective: Fetal alcohol syndrome (FAS) is a well-established diagnosis associating neurodevelopmental disorders and characteristic facial features induced by prenatal alcohol exposure. While brain is particularly affected, neuroanatomical features involved in diagnosis are unspecified, apart from microcephaly, and contribute little to specificity. Furthermore, in the absence of the characteristic facial features, the diagnosis of Non-Syndromic Fetal Alcohol Spectrum Disorder (NS-FASD) remains difficult and probabilistic. The aim of our study was to assess the presence of objective MRI brain anomalies in patients with FASD and see how they can contribute to the diagnosis. Methods: In this retrospective monocentric study brain MRI were performed for 89 patients (6 to 20 years old) diagnosed with FASD including 52 FAS patients and 37 NS-FASD and for 94 typically developing age-matched controls. MRI were performed using 3D IR GE T1 sequence with millimetric isotropic resolution at 1.5T (all patients and 41 sequence-paired controls) and 3T (other controls). For each subject a reference brain area, the length and the thicknesses of the corpus callosum in 4 different parts and the height of the vermis were measured. The foliation of the upper vermis was evaluated according to an original 5-rank Likert scale. Normative curves with 10th centile assessment were established in controls for each parameter according to age and to the reference brain surface area. Results: Reference brain area, corpus callosum length, isthmus and splenium thickness, and height of the vermis were significantly smaller in the FASD population. The reference brain area was reduced for age (<10e p) in 48/52 FAS and 27/37 NS-FASD patients. There was an excess of FAS patients with a callosal isthmus thinner than expected for their reference brain surface area (<10e p, p=0.0027). Abnormal corpus callosum (partial agenesis or isthmus thickness <10ep) was found in 16/ 52 FAS and 6/37 NS-FASD. There was an excess of FAS patients with a vermian height smaller than expected for their reference brain surface area (p<0.0001). According to the proposed vermis Likert scale, 16/89 FASD patients showed abnormal upper foliation (18% vs. 0 control). The interobserver agreement for ranks 4 and 5 (abnormal) was strong (?=0.65). Abnormal vermis (ranks 4/5 and/or vermian height <10ep) was found in 25/52 FAS and 10/37 NS-FASD. Finally, 20/52 (38%) FAS and 10/37 (27%) NS-FASD had at least 2 anomalies (vs. 2% of controls) and 10/52 FAS had all 3 anomalies (19% vs. 0 control): decreased brain area, abnormal corpus callosum and abnormal vermis. Conclusion: Patients with FAS but also NS-FASD were found to present corpus callosum and cerebellar vermis abnormalities that in combination with microcephaly could help suggest a FASD in a context of neurodevelopmental disorders, and contribute to the specificity of the diagnosis especially in non-syndromic patients. Objective: To describe the appearances of bone marrow on fatsuppressed T2-weighted sequences as seen on whole-body MRI in healthy and asymptomatic children and adolescents. Material and methods: Following ethical approval, we assessed the bone marrow of the whole skeleton on water-only Dixon T2-weighted images as part of a whole-body MRI in 196 healthy and asymptomatic children aged 5-19 years. Based on a newly devised and validated scoring system, we graded intensity (0-2 scale) and extension (1-4 scale) of focal high signal bone marrow areas, and divided them into minor or major findings, based on intensity and extension, reflecting their potential conspicuousness in a clinical setting. Results: In total we registered 1383 focal high signal bone marrow areas, whereof 494 (35.7%) were defined as major findings. 294 high signal areas were seen in the upper extremities (79 (26.9%) major findings); 674 were seen in the lower extremities (340 (50.4%) major findings) and 415 areas were seen in the axial skeleton (75 (18.1%) major findings). Hundred-andforty-seven individuals (75.0%) had at least one major finding, mainly located in the lower limbs, hand and pelvis. There were no significant differences according to gender, reported hours of sports activity, handedness, or age group, except for minor findings, where there was a significantly higher mean score in the oldest age-group compared to the youngest age-group both in the axial skeleton (p=0.02) and the upper limbs (p=0.042). In the appendicular skeleton, the most striking findings were in the feet, particularly the metatarsals and tarsal bones, followed by the knees. In the axial skeleton, the most conspicuous findings were seen in the pelvis, spine, and sternum. Conclusion: Focal areas of high signal intensity on whole-body MRI, T2-weighted fat suppressed images that, in a clinical setting could cause concern, were seen in 3/4 of healthy, asymptomatic children and adolescents. Awareness of this is important when interpreting whole-body MRI in this age group, particularly in the assessment of clinically silent lesions.

Purpose: Portal hypertension (PHT) in children can be related to extrahepatic portal vein obstruction (EHPVO) with cavernomatous transformation. Meso-Rex by-pass procedure has been developed by surgeons to treat PHT while restoring a physiological portal flow to the liver. Even if poorly described in the literature, Interventional radiology (IR) can also allow portal reperfusion of the liver either by simple angioplasty or by creating a new pathway with stents between mesenteric or splenic veins and intrahepatic portal veins (IHPV). We aim to report 4 cases of pediatric EHPVO successfully treated by interventional radiology (IR). Materials and Methods: Between 2000 and 2021, 4 children, aged ( 5yo to 10 yo) had successful treatment of EHPVO with IR. Clinics, biology, endoscopy, Echo-Doppler, and Elastography techniques before and after treatment were collected. Results: All procedures were done under general anesthesia using USguided transhepatic portal access. Two patients were treated using percutaneous angioplasty as follows: one had a hypoplastic main portal vein unseen on conventional imaging (US, CT-scan) but revealed during angiography, stenosis that could be treated by balloon dilatation. Normalization of PHS and disappearance of cavernomatous veins were seen at 1-month follow-up (FU). The other patient had significant stenosis between a vein of the cavernoma and the portal bifurcation, which was treated using balloon dilatation, with PHT improvement, followed by a second angioplasty 6 months later. There was no significant PHT during 5 years FU. The two other patients were treated by creating a new pathway by-passing the obstruction using self-expandable stents through cavernomatous veins between the right portal branch and the extrahepatic portal network. Both patients had complete thrombosis of the stents the day after the procedure that resolved after 1 month of anticoagulation therapy. One patient had a complete resolution of PHT during 2 years FU. The second patient had a recurrence of PHT 1 year after the procedure due to a stenosis of the right portal vein downstream the stents, resolved by angioplasty and additional stent placement. Conclusion: Reportalisation of the liver in children with EHPVO is possible either by angioplasty of stenosis of the portal vein or cavernomatous veins or by the creation of a pathway by-passing portal obstruction using stents between veins afferent to the portal vein and IHPV. Both technics can cure PHT with lower morbidity than surgery. Background: Real-time MRI based on FLASH 2.0 is extremely robust against artefacts due to pulmonary and cardiac motion as well as bulk movement of the patient. To date, there are no reports on application of this innovative technique in pediatric lung MRI. Objective: The aim of this study was to summarize a first experience after two years of employing real-time MRI in pediatric lung imaging. In particular, we aimed to assess types and minimal size of lesions to be detected with this new sequence. Materials and methods: In this retrospective study pathological lung findings of 87 children were classified into 6 subgroups, as detected on conventional MRI (metastases and tumors, consolidation, scars, hyperinflation, interstitial pathology, bronchiectasis). Subsequently, the findings were grouped according to size (4-6mm, 7-9mm, >10 mm) and evaluated for visual delineation of the findings (0=not visible, 1= hardly visible, 2=well visible). Videos of several pathologies have been sampled for demonstration. Results: As the video examples demonstrate, real-time MRI allows for artefact-free images of the thorax with diagnostic quality can be obtained, regardless of patient movements. Delineability of findings strongly correlate with the size of the pathology: When larger than 9 mm, as in metastases, consolidations and scars, each finding was well visible. Though rarely not visible, smaller pathological objects of 4-9 mm in size do not regularly meet the expected diagnostic confidence. Diffuse interstitial lung changes and hyperinflation, known as "MR-minus pathologies", are not accessible to real-time MRI. Conclusion: The method provides motion robust images of the lung and thorax. However, the lower sensitivity for small lung findings is a major limitation for routine use. In our daily routine, we employ real-time MRI complementary to conventional sequences in young children with irregular breathing patterns or bulk motion in sedation-free MRI. Currently, method is already adequate for diagnosis and follow-up examinations of inflammatory lung diseases, atelectasis, effusions as well as lung scarring. A medium-term goal is to improve the diagnostic accuracy of small nodules and interstitial lesions. Methods & Materials: Tracheobronchomalacia refers to the excessive flattening of the tracheal lumen and/or the main bronchi due to "weakening" of the cartilaginous rings or the posterior muscular wall. A paired end-inspiration/forced-expiration protocol is required to demonstrate the pathology when performing a CT scan. The diagnostic criterion is at least a 50% reduction of tracheal luminal area in expiration. Recent studies introduced the use of dynamic MRI as an alternative non-ionizing technique. This is a prospective ongoing study, starting on the 03/2021, which includes so far twelve children (8 males, 4 females) with a median age of 10,5 years. Patients underwent both paired CT scans and dynamic MRI scans. The CT examination was performed on a 64-slice CT scanner using a protocol that included a deep inspiration scan with 1.25 mm slice thickness and a forced expiration scan with 1.25 mm slice thickness. The MRI examination was performed on a 1.5T MRI machine using static and dynamic sequences for pathology assessment. Results: The tracheal lumen reduction was calculated in each exam for the same patient and the data were statistically analyzed using a paired Ttest. Our study concluded that there is a statistically significant difference between the two examination types in favor of MRI when diagnosing tracheobronchomalacia (pvalue = 0.0172). Moreover, we found that there is a statistically significant difference when using dynamic MRI images compared to static MRI images in deep inspiration and forced expiration (pvalue=0.0172). Conclusion: Although our study uses a small cohort, preliminary results favor the use of dynamic MRI scan in the diagnosis of tracheobronchomalacia compared to CT scan, which further empowers MRI as a non-ionizing, non-invasive diagnostic technique in the pediatric population. Purpose: Right ventricular fibrosis is an important risk factor in patients with repaired TOF as it leads to RV dysfunction or even RV failure. Native T1 mapping is a tissue characterization method to detect diffuse myocardial fibrosis. The purpose of this study was to evaluate the relationship between structural and functional/hemodynamic patterns in adolescent patients with repaired TOF by cardiac magnetic resonance (CMR). Material and Methods: So far, 5 male adolescent patients with repaired TOF, age 15 ± 3 years, underwent cardiac MRI at 1.5 T. The RV and LV function as well as the indexed right and left ventricular end-diastolic volumes were calculated. 2D flow measurements were performed in the main pulmonary artery. Native LV and RV T1 times were obtained for the RV outflow tract, the RV free wall, the LV septum and the LV free wall using a modified look-locker inversion recovery (MOLLI) sequence. The results were compared between the right and left ventricle and also correlated to the flow and functional patterns. Results: Two TOF patients had elevated indexed right ventricular enddiastolic volumes. The mean RV ejection fraction in the study group was 39,6 ± 8,6 %, the mean LV ejection fraction was 52,6 ± 7 %. The highest T1 times were found in the RV outflow tract (1055 ± 48 ms). There were significant differences in the mean native T1 times of the right and left ventricle (p < ±0,05). High correlations were observed between mean native T1 times of the right ventricle and maximum flow velocities (r = 0,79) as well as the pulmonary regurgitation fraction (r = 0,61). A mild correlation was found between mean native T1 times of the right ventricle and the indexed right ventricular end-diastolic volumes (r = 0,57). There was no correlation between mean native T1 times of the left ventricle and the indexed left ventricular end-diastolic volumes (r = -0,12). Conclusion: Adolescent patients with repaired TOF seem to have diffuse right myocardial fibrosis, particularly in the RV outflow tract. No signs of fibrosis were found for the left ventricle. Higher native T1 times of the right myocardium are associated with pathologic flow patterns in the pulmonary artery and the dilatation of the right ventricle. Background: CT Coronary Angiography (CTCA) is a useful tool in evaluating paediatric coronary artery anatomy and pathology, particularly in congenital heart disease. CTCA is a potentially high-dose CT technique and matching required image quality to clinical indication is essential in rationalizing exposure in vulnerable patients. Aim: To compare image quality and radiation dose from non-gated, and single-and multi-phase ECG-gated protocols in 0-2 year-old undergoing cardiac CT examinations. Materials and Methods: A retrospective study was carried out in a quaternary paediatric cardiac surgical center, identifying children under 2 years of age undergoing CT on a Siemens Definition FLASH. 4 protocols were examined: non-gated FLASH (high-pitch spiral); ECG-gated FLASH; single-phase sequential (30% R-R) and multiphase sequential (30-50% R-R). Study indication, heart rate and CTDIvol were recorded.

Visualization of the left mainstem artery (LMS) was recorded using a two-point scale: (not visible vs visible) and quality of the left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA) was subjectively scored using a four-point scale (0 = artery not visible; 1 = only origin visible; 2 = artery visible to mid-portion; 3 = full vessel visible). Results: 71 in under 2-year-old (20 sequential ECG-gated, 20 ECG-gated FLASH and 31 non-gated FLASH). Of the Sequential scans, 5 were single phase and 15 were multiphase. Median age was 3 months. Coronary visualization was higher in sequential scans (median score 7) compared to gated-FLASH (5.5, p=0.12) and non-gated FLASH (5, p=0 .01) with no significant difference between gated and non-gated FLASH modes (p=0.42). Multiphase sequential was higher quality (median score 8) than single phase sequential (median 6), but not significantly so (p=0.12). As should be expected, radiation exposure was highest from the multiphase protocol (median CTDIvol 1.63mGy (single-phase sequential 1.2mGy; ECG-gated FLASH 0.56mGy; non-gated FLASH 0.47mGy). Sequential scans were better able to maintain image quality at high heart rates than gated-FLASH scans. Conclusion: Sequential scanning provides better quality coronary imaging, but at a significantly higher dose than FLASH scanning. Scan protocols should match indications with higher dose protocols only used when coronary analysis is required. Purpose: In clinical assessment of Pectus Excavatum (PE), the indication to surgery is based not only on symptoms but also on quantitative markers calculated from Computed Tomography or Magnetic Resonance Imaging (MRI) scans. According to clinical routine, these indexes are measured manually by radiologists with limited computer support. This process is time consuming and potentially subjected to inaccuracy and individual variability in measurements. Moreover, the existing indexes have limitations, since they are based on linear measurements performed on single slices rather than on volumetric data derived from all the thoracic scans. We present an image processing pipeline aimed at providing radiologists with a computer-aid tool in support of diagnosis of PE patients developed in MATLAB ® and conceived for MRI images. This framework has a dual purpose: (i) to automatize computation of clinical indexes with a view to ease and standardize pre-operative evaluation; (ii) to propose a new marker of pathological severity based on volumetric analysis and overcoming the limitations of existing axial slice-based indexes. Materials: Final designed framework is semi-automatic, requiring some user interventions at crucial steps: this is realized through a Graphical User Interface (GUI) that simplifies the interaction between the user and the tools. We tested our pipeline on 50 pediatric patients from a Children's Hospital of national relevance, and performed manual computation of indexes, comparing the results between the proposed tool and gold-standard clinical practice. Automatic indexes provided by our algorithm have shown good agreement with manual measurements by two independent readers. Moreover, the new proposed Volumetric Correction Index (VCI) has exhibited good correlation with standardized markers of pathological severity, proving to be a potential innovative tool for diagnosis, treatment, and follow-up. Conclusions: Our pipeline represents an innovative image processing in PE evaluation, based on MRI images and providing the clinician with a quick and accurate tool for automatically calculating the classical PE severity indexes and a new more comprehensive marker: the Volumetric Correction Index.

Daniel Gräfe 1 , Martin Lacher 3 , Franz Wolfgang Hirsch 1 , Jens Frahm 2 , Peter Zimmermann 3 1. University Hospital -Pediatric Radiology, Leipzig, Germany 2. Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany 3. University Hospital -Pediatric Surgery, Leipzig, Germany

Purpose: The breathing phase for the determination of thoracic indices in patients with pectus excavatum is not standardized. The aim of this study was to identify the best period for reliable assessments of morphologic indices by dynamic observations of the chest wall using real-time MRI. Material and Methods: In this prospective study, patients with pectus excavatum underwent morphologic evaluation by real-time MRI between January 2020 and June 2021. Haller Index (HI), Correction Index (CI), modified Asymmetry Index (AI), and modified Eccentricity Index (EI) were determined during free, quiet, and forced breathing respectively. Breathing-related differences in the thoracic indices were analysed with the Wilcoxon signed-rank test. Motion of the anterior chest wall was analysed as well.

Results: A total of 56 patients (11 females and 45 males, median age 15.4 years, interquartile range 14.3?16.9) were included. In quiet expiration, the median HI in the cohort equalled 5.7 (4.5-7.2). The median absolute differences in the thoracic indices between peak inspiration and peak expiration were HI = 1.1 (0.7-1.6, p <.001), CI = 4.8 % (1.3?7.5 %, p <.001), AI = 3.0% (1.0%-5.0%, p <.001), and EI = 8.0% (3.0%-14.0%, p <.05). The indices varied significantly during different inspiratory phases, but not during expiration (p >.05 each). Furthermore, the dynamic evaluation revealed three distinctive movement patterns of the funnel chest. Conclusions: Thoracic indices of pectus excavatum should be assessed in the end-expiratory phase of quiet expiration. Purpose: To evaluate feasibility of an abbreviated large field of view MR imaging protocol using Ferumoxytol blood-pool contrast agent to characterize diffuse and syndromic vascular anomalies. Methods & Materials: Following IRB approval, clinical, imaging and management information from 27 patients(15 M,12 F) with mean age of 11.9 (0.2-52) years, and mean weight of 56 (7-156) kg, who underwent MR imaging using the diffuse vascular anomalies protocol was reviewed. Imaging performed on a Siemens Skyra or Prisma 3T scanner included composite 3D RAVE/VIBE, composite axial SSFSE T2 without fat saturation, and composite 3D T2-SPACE (3DT2). Ferumoxytol (2.4 mg/kg (range 1-3.5 mg/kg)) was administered. Technical image quality for each sequence and clinical grading of reporting elements was graded by 2 experienced pediatric vascular imagers. Descriptive statistics were utilized. Results: Imaging indications included prior diagnosis of a syndromic or genetic lesion (60%), or leg length discrepancy/overgrowth/varicosities/ edema/capillary stain. The full protocol including composite image creation was successful in 62.3% with a learning curve demonstrated over time. Average number of stations performed were RAVE (2.4), VIBE (4.3), SSFSE (3.6) and 3DT2 (2.6). Mean scan time per subject was 62 min (26-123min). Average technical image quality scores were 4.5/5 for RAVE, 4.3 for VIBE, 4.8 for SSFSE, and 3.6 for 3DT 2. All studies were diagnostic, with RAVE/VIBE and SSFSE mandatory for adequate assessment. Mean clinical grade of reporting elements were: arteries (4.4/ 5), deep veins (4.6), superficial veins (4.7), anomalous veins (4.7), superficial venous malformations (VM) (4.7), deep/intramuscular VM (4.8), macrocystic lymphatic malformations (LM) SSFSE (4.7) and 3DT2 (4.2), microcystic LM SSFSE (4.6) and 3DT2 (4.3), limb size discrepancy (4.6), fatty hypertrophy (4.6), edema SSFSE (4.3) and 3DT2 (4), and visceral (4.8), spine (4.2)and bone involvement (4.7). Even with prior vascular anomaly specialist assessment in 74% of cases, the final diagnosis and management plan was changed in 66% of cases after imaging, with a specific diagnosis of PIK3CA/CLOVES rendered in 46.7%. Conclusions: We demonstrate feasibility of an abbreviated 60 minutes, large FOV MR imaging protocol using Ferumoxytol blood pool contrast for syndromic/diffuse vascular anomalies with extensive involvement. Based on this experience, we adopted a final protocol comprising 3D RAVE in smaller children, 3D VIBE in larger patients, and composite axial SSFSE T2 without fat saturation. Purpose: Thickened corpus callosum (CC) is a known feature of neurofibromatosis type 1 (NF1). While we have previously reported differences in patients with NF1 compared to age-appropriate reference standards, we sought to measure CC through our semi-automated measurement method in patients with NF1 and compared them to unaffected controls seen at our institution. Methods: A retrospective analysis of patients with and without NF1 was conducted. Controls were included if they did not have comorbidities and had an MRI for headache that was deemed unremarkable in the radiology report. Patients with any imaging findings or comorbidities were excluded. Midline T1 sagittal MR images underwent retrospective CC thickness measurement using a customized semi-automated MATLAB tool. Patient demographics and clinical evaluations were obtained from the electronical medical record. Mann-Whitney tests were used to compare the CC thickness at the level of the genu, body, isthmus and splenium between cases and controls. Logistic regression was used to compare different behavioral and developmental associations between cases and controls. Results: 209 patients (70 controls and 139 cases); median age cases 9 (5.62-14.27 IQR), controls 12 (5.14 -16.11 IQR), female (53.11%), were included. CC median thickness at all locations (genu, body, isthmus and splenium) were statistically significantly thicker in cases than controls (p value <0.05). Median CC thickness was significantly larger at the genu (p-value 0.04) and body (p-value 0.03). ADHD (p-value 0.000), learning disorders (p-value 0.001), and global delay (p-value 0.04) was significantly higher in patients with NF1. Conclusion: Semi-automated evaluation of CC thickness demonstrated thicker CC median values in children with NF1 than controls. The CC was significantly thicker in patients with ADHD, learning disorders and global delay. Further studies with larger sample sizes, and longitudinal assessments would expound the relationship between CC thickness and these disorders in children with NF 1. Background and Purpose: Enlarged perivascular spaces (EPVS) are associated with various cerebral diseases, but few reports mention their presence in cortical developmental disorders. We investigated frequency and conspicuity of EPVS underneath dysplastic cortex as a potentially underrecognized feature of polymicrogyria (PMG) in magnetic resonance imaging (MRI). Methods: We reviewed data from 48 PMG patients (age 2 days-53 years) that underwent 1.5T (n=22) or 3T (n=26) MRI. Patients received ageadjusted protocols according to myelination status (0-18 months n=11; 18 months-4 years n=3; >4 years n=34) including the following sequences: T1-weighted (w)(n=47), T2w (n=48), FLAIR (n=42), 3D MPRAGE (n=34) and 3D FLAIR (n=21). Two raters analyzed images for EPVS underneath PMG and classified them as non-visible, barely visible and clearly visible. Results: EPVS spatially related to PMG were identified in 30/48 (62.5%) patients with 14/22 (63.6%) at 1.5T and 16/26 (61.5%) at 3T MRI. There were no significant differences between PMG location and the presence of EPVS. Interrater variability for the detection of PMG-associated EPVS was lowest for T2w (k=0.71, agreement 75.0%), followed by 3D MPRAGE, T1w, 3D FLAIR and FLAIR (k=0.66, 0.49, 0.43 and 0.39, agreement 79.4%, 78.7%, 81.0%, and 78.6%). Recognition of EPVS was not different between 1.5T and 3T. Conclusion: EPVS adjacent to PMG were found in about 63% of patients. Therefore, EPVS may be an important clue for PMG, and a surrogate marker for a cortical malformation. MR sequence, but not field strength, impacts their detection. T2w images seem to be most reliable, regardless of the patient's age.

Stephen Little 1 , Asha Sarma 2 , Kartik Reddy 1 , Manish Bajaj 1 , Sumit Pruthi 2 , Bryan Philbrook 1 , Andrew Reisner 1 , Lori Jordan 2 1. Emory University and Children's Healthcare of Atlanta, Atlanta, United States 2. Vanderbilt Children's Hospital, Nashville, United States Purpose: Vertebral artery dissection (VAD) is missed on the majority of clinically performed two-dimensional time-of-flight magnetic resonance angiography (2D-TOF MRA) examinations. Contrast-enhanced MRA (CE-MRA) mitigates some of the shortcomings of 2D-TOF MRA but introduces some of its own. Even so, the International Paediatric Stroke Study Neuroimaging Consortium and the Paediatric Stroke Neuroimaging Consortium have recommended 2D-TOF MRA or CE-MRA of the neck for first line stroke evaluation. We hypothesize that a) CTA or 3D-TOF MRA visualizes more features of vertebral artery dissection than 2D-TOF or CE-MRA and that b) CT/CTA reveals associated potentially pathogenic osseous anomalies. The purpose of this study is to compare the ability of CTA and MRA to identify and characterize VAD in children. Material and Methods: This is a retrospective analysis of childhood VAD identified from two tertiary centers over 20 years. All available neuroimaging was evaluated for findings of isolated posterior circulation arterial ischemic stroke and VAD according to CASCADE criteria. Readers also subjectively rated each study on the basis of whether the imaging findings were more clearly displayed with CT/CTA or MR/ MRA or were equally apparent. Osseous anomalies were described and proximity to dissected arterial segments was noted. Maximum intensity projection and volume-rendered images were produced to better demonstrate vascular and osseous findings as needed.

Results: As part of an ongoing study, vertebral artery dissection was identified in 20 children (14 male, 6 female). Median age was 7.4 years. CTA was performed in 17 children. Additional cervical vascular imaging techniques employed include 2D-TOF MRA, 3D-TOF MRA, CE-MRA and digital subtraction angiography (DSA). CTA and 3D-TOF MRA identified more stenoses, pseudoaneurysms and intimal flaps than 2D-TOF MRA or CE-MRA. CT/CTA was preferred for concurrent demonstration of arterial and osseous abnormalities. Conclusions: CTA and 3D-TOF MRA are superior to 2D-TOF MRA or CE-MRA for the diagnosis of VAD in children. Current IPSS imaging recommendations for cervical vascular imaging may result in substantial underdiagnosis of VAD in children. Cervical CTA or 3D TOF MRA should be performed for non-invasive evaluation whenever VAD is suspected. CT/ CTA allows for demonstration of associated osseous anomalies. Introduction: Dynamic susceptibility contrast (DSC) perfusion imaging is usefull in multimodal MRI. It is used for brain tumours characterisation and for differentiating between tumour recurrence and radionecrosis in adults. Unfortunately, the contrast agent administration flow rate is low in children and may lead to non-valid perfusion analysis. The aim of this study is to demonstrate that the use of the regular injection rate allowed by the venous access and the patient's age provides similar tissue and vascular Maximum Signal Drop (MSD) in children and adult. This would further allow the use of DSC in paediatrics. Materials and methods: This prospective study was conducted between November 2017 and April 2018. DSC MRI was performed in 75 children aged between 4 months to 17 years and in 17 adults who formed the control group. For each child, 12 regions of the brain were studied by 2 observers, who were unaware of both the measurements taken by the other, and the perfusion flow rate. Results: There was no significant difference in mean MSD in the cerebral arteries between the group of adults and the group of children at high perfusion flow rate (p>0.05). Basilar MSD were uninterpretable. In the centrum ovales, MSD were similar in all subjects of 8 months or older (p>0.05). Conclusion: T2EG first-pass perfusion sequence can be carried out successfully in most paediatric patients despite the lower flow rate than the one used for adults. However, injection through an implantable catheter does not allow a sufficient flow rate. Purpose: Many pediatric emergencies arrive overnight, when hospital staffing is limited. Radiology services may be covered by generalists, while subspecialized radiologists take call from home. At our tertiary pediatric hospital, a pediatric neuroradiologist is on call for emergency magnetic resonance (MR) imaging. To ensure on-call staff are called only for medically emergent cases, we developed and implemented consensus guidelines for emergent pediatric neuroimaging overnight. Materials and Methods: Institutional review board approval was not required for this improvement project. Guidelines for MR neuroimaging triage at our 594-bed main hospital and several community hospitals were developed by interviews and iterative approval by a multi-disciplinary consensus group of neuroradiologists, an overnight radiologist, and neurological clinical services. During implementation, 4 body-trained pediatric radiologists triaged overnight requests as do immediately, defer to the next day, or divert to computed tomography (CT) imaging. During a 10-week trial, overnight radiologists tracked number of calls taken, time per call, triage decision, and difficulty of the triage call. Triage difficulty was ranked on a 10-point subjective scale (1 = very easy, 10 = very hard). Overnight radiologists documented decision-making in a triage note that was reviewed and feedback given by the neuroradiologist on call. Results: Consensus emergent MR indications included: emergent brain abnormality or unstable spine injury identified on other imaging or clinical signs of cord compression. In addition, 5-minute rapid brain MR could be approved for children > 6 years old when clinical concern was not for trauma, hemorrhage, or seizure; these indications would be diverted to CT. All other requests were deferred. In 10 weeks (70 nights), overnight radiologists handled 43 calls (0-3 calls per shift). Mean triage time was 10 minutes (range 1-40 minutes). Overnight neuro MR was approved in 15 cases, deferred in 13 cases, and diverted to CT in 4 cases. Five calls were for clinical consult, two for assisting the reading room clerk, and four calls were incompletely documented. In 24 cases (56%), triage system prevented waking the on-call neuroradiologist. Neuroradiologists agreed with the triage decision 66% of the time. Overnight radiologists ranked mean knowledge difficulty as 3.1 (range 1-7) and mean psychological difficulty as 3.5 (range 1-10). Conclusions: An overnight triage system for neuro MR requests may prevent over half of calls that would otherwise wake on-call neuroradiologists. Triage is manageable for overnight radiologists, but there are opportunities for decreasing difficulty of triage calls and improving decision-making. Triage guidance may further decrease overnight calls by providing decision support for ordering clinicians. Purpose: Neonates with severe cardiopulmonary compromise may require extracorporeal membrane oxygenation (ECMO) therapy, which poses an increased risk in neurological complications and mortality. Microvascular imaging (MVI) is an advanced Doppler technique which allows high-resolution visualization of microvasculature in the brain. We aim to assess cerebral microvascular morphology as assessed using MVI as a potential prognostic biomarker in patients undergoing ECMO. Materials and Methods: Brain MVI scans of neonates undergoing ECMO were retrospectively analyzed in a 1-year period. A pediatric radiologist, blinded to patient information and outcome, assessed MVI scans to determine the presence or absence of tortuosity, symmetry, heterogeneity, engorgement, and hypoperfusion of the lenticulostriate vessels, as well as the presence or absence of asymmetry in white matter flow, white matter engorgement, and increased peri-gyral flow in the cortex. The earliest MVI scan available after initiation of ECMO was used. Chi-squared analysis was used to determine significant differences in imaging findings between patients who died and patients alive within one year of ECMO decannulation. Results: 24 patients (mean age 25.8±50.45 days, 13 female) had brain MVI scans while on ECMO. 15 patients underwent ECMO for pulmonary failure, 5 for failure to wean from cardiopulmonary bypass, and 4 patients for cardiac failure. The average duration of ECMO at time of scan was 12.29±3.79 days. 6 patients (25%) died within one year of ECMO decannulation. There was a statistically significant difference in the presence of white matter engorgement of the cortex in patients who died (p=.020) compared to those who did not die. There was no statistical significance between death and lenticulostriate vasculature abnormalities, or asymmetry in white matter flow and increased peri-gyral flow in the cortex. While not significant, a trend toward increased peri-gyral flow in patients who died (p=0.077) was observed. Conclusion: Cerebral microvascular alterations as assessed using MVI during ECMO may offer early prognostic information. Our initial finding is of clinical significance and warrants further investigation via larger prospective studies, as the evaluation of brain health during ECMO is largely limited to serial grayscale brain ultrasounds in infants. The pathologic implications of cerebral microvascular alterations also need further investigation, as this can lead to novel therapeutic targets and imageguided interventions in the future. Background: Liver and spleen stiffness measurement (LSM, SSM) in the context of liver transplantation (LT) has been poorly studied until now. Even if the acute post-transplantation period is complex, ultrasound LSM and SSM may be interesting to evaluate early graft condition and detect complications. Patients and methods: Prospective study including paediatric liver recipients with collection of clinical and biological data, LSM and SSM regularly until month 6. 3 different patterns of LSM and SSM changes over time were defined: 1: continuous decrease, 2: plateau at a high level or continuous increase, 3: sporadic increase. Diagnostic performances of LSM and SSM for the diagnosis of complications were evaluated. Results: 57 liver recipients were studied, median age 2.3 y (from 0.3 to 15.2 y). 15 had no significant complication. 42 had one or several significant complications including: 30 infections, 23 acute rejection, 13 septic liver on histology, 32 biliary complications, vascular complications: 9 hepatic artery, 14 portal vein, 6 hepatic veins. LSM had a positive predictive value (PPV) of 88%, a negative predictive value (NPV) of 33%, a sensitivity of 88%, and a specificity of 66%. An abnormal LSM curve was associated with the occurrence: acute rejection, or refractory ascites, or multiple complications in 100% of cases, infection in 86.7%, and biliary complications in 75%. SSM had a PPV of 97.6%, a NPV of 46.6%, a sensitivity of 83.7%, and a specificity of 87.5%. An abnormal SSM curve was associated with the occurrence: infection, or portal vein complications or refractory ascites or multiple complications in 100% of cases, acute rejection or biliary complications in 85.7%. Conclusion: LSM and SSM are good biomarkers of complications following LT in children. LSM and SSM decreases after LT without complication. Sporadic increase, continuous increase or plateauing at a high level, of LSM and SSM have very good PPVs for complications. However, a normal trend of LSM and SSM does not preclude the occurrence of a complication. Purpose: Doppler ultrasound (DUS) is widely used to detect vascular complications after pediatric liver transplantation (LT). This study aimed to assess the moment of first detection of vascular complications with DUS after LT and to determine the positive predictive value (PPV) of DUS. Material and methods: Patients aged 0-18 years who underwent LT between 2015 and 2019 were retrospectively included. Ninety-two LTs in 83 patients were included (median age at LT 3.9 years, interquartile range 0.7-10.5). All patients underwent standard perioperative (intraoperative and immediately postoperative) and daily DUS surveillance during the first postoperative week, and at 1, 3 and 12 months. Vascular complications diagnosed by DUS were specified for the hepatic artery, portal vein and hepatic veins. Abnormal DUS findings were compared to surgical or radiological findings during 1-year follow-up. Results: Fifty-two vascular complications were diagnosed by DUS in 35/ 92 LTs (38%) during 1-year follow-up. Fifteen out of 52 (28.8%) were diagnosed perioperatively, 29/52 (55.8%) were diagnosed on postoperative day 1-7, and 8/52 (15.4%) were diagnosed after day 7. PPV for all vascular complications diagnosed with DUS was 92.3%. During 1-year follow-up, 18/19 (94.7%) hepatic artery complications, 17/26 (65.4%) portal vein complications, and 7/7 (100%) hepatic vein complications were diagnosed perioperatively or during the first week. Conclusions: The vast majority of vascular complications during the first year after pediatric LT were diagnosed by DUS perioperatively or during the first week, with a high PPV. Our findings provide important information regarding when to expect different types of vascular complications on DUS, which might improve DUS post-LT surveillance protocols. Purpose: To evaluate the feasibility to use multiple quantitative ultrasound markers for characterization of fibrosis, inflammation, and steatosis in the liver non-invasively in pediatric patients. Methods: In pediatric liver patients, the quantitative ultrasound measures shear wave elastography (SWE), shear wave dispersion (SWD) and attenuation imaging (ATI) were compared with percutaneous liver biopsy performed the same day, and corresponding measures in a control cohort. Fibrosis was scored according to Batts & Ludwig classification (F0-F4), inflammation graded none-severe (0-3) and steatosis according to nonalcoholic fatty liver disease score (0-3). Results: The median age for 32 patients was 12.1 years (range 0.1-17.9) and for 15 controls 11.8 years (range: 2.6-16.6). There was significant difference in SWE-values between histologic grades of fibrosis (p=0.003), with positive correlation according to grades (r=0.7; p<0.0001). Overall, a difference in SWD-values between grades of inflammation was found (p=0.009), but lack of correlation (r=0.1; p=0.67). Comparing inflammation grade 0-1 (median:13.6 m/s kHz [min:max;8.4;17.5]) versus grade 2-3 (16.3 m/s kHz [14.6;24.2]) showed significant difference between the groups (p=0.003). In the 30 individuals with steatosis score 0, ATI was measured in 23 cases with median value 0.56dB/cm/MHz. In the single individual with steatosis score>0, median ATI was 0.82 dB/cm/MHz. Conclusion: Comprehensive ultrasound analysis, using the quantitative markers SWE, SWD and ATI, was feasible in children, also with freebreathing, and have potential to reflect the various components of liver affection non-invasively. Awaiting further research, these image-based markers could likely be used clinically to rule out significant fibrosis, inflammation and steatosis in children. However, this needs to be established in larger studies. Purpose: Focal renal infections like focal nephritis and renal abscesses are not very common in children. However, they have to be diagnosed early in order to enable an appropriate antibiotic treatment. The final diagnosis is conventionally determined by computed tomography accompanied by high radiation burden or magnetic resonance imaging requiring sedation, which limits its use in children. The purpose of this paper was to investigate the efficacy and clinical utility of intravenous renal contrastenhanced ultrasound (CEUS) as an alternative imaging method for a diagnosis and follow-up of focal renal infections in children which was performed as a continuation of the conventional ultrasound. Material and methods: Thirteen children aged from 6 months to 17 years (mean 6.0 years) in whom focal renal infection was suspected were included in this retrospective study. All clinical, laboratory, treatment and imaging data were obtained from medical and imaging records of the patients. Results: CEUS was performed for diagnosis in children with suspected focal renal infection in all thirteen children and then also for follow-up in six children with renal abscess. In three children enhancement pattern was concordant with focal nephritis and in four children CEUS excluded focal renal infection and the diagnosis of pseudolesion was confirmed. All clinically relevant imaging data regarding focal renal infection was obtained by CEUS, which offered an objective evaluation of lesion status regarding the size and structural changes. The diagnosis was made immediately and the treatment started without delay. No other imaging was necessary for diagnosis and follow-up. Conclusions: Renal CEUS was proven to be a radiation ad sedation free, safe, efficient and self-sufficient imaging in diagnosis and further followup of focal renal infections in children. CEUS patterns of focal renal infections like focal nephritis, renal parenchymal and subcapsular renal abscess are described as well as relevant CEUS enhancement patterns important for differential diagnosis. Renal abscess follow-up algorithm with CEUS is suggested. Purpose: The aim of the study is to investigate relationship between renal function tests and elasticity of the transplanted kidneys in children, which can help to find new parameter for detection of transplant disfunction in the early period and decrease unnecessary biopsies. Material and methods: One operator measured renal transplant elasticity with shear wave elastography in 21 children who had renal doppler ultrasonography in our institution between February and October 2021. In every transplanted kidney, 12 measurements of different regions with same region of interest size (0.1 cm2) were calculated by using linear probe (2-9 MHz). The correlation between mean-median of elasticity values in kPa and laboratory values (creatinine, cystatin C, blood urea nitrogen and albumin) with estimated glomerular filtration (eGFR) rate was tested. Spearman correlation coefficient used as a statistical test. Results and Conclusions: Twelve males and nine females included in the study with mean age 9.6-year-old ranging from 1,5 to 17-year-old. None of the patients had any symptoms or change in urine amount and color. All the patients had creatinine, blood urea nitrogen and albumin values and 20 patients had cystatin value in the same week with the elastography. There was no statistically significant correlation between means of the elasticity values and eGFR (rs= 0.12; p value= 0.59), cystatin c (rs= 0.31; p value= 0.17), blood urea nitrogen (rs= 0.29; p value= 0.2), albumin (rs= -0.14; p value= 0.57). Also, medians of the elasticity values were not correlated with eGFR (rs= 0.13; p value= 0.57), cystatin c (rs= 0.3 p value= 0.2), blood urea nitrogen (rs= 0.34; p value= 0.13), albumin (rs= -0.1; p value= 0.67). Although cystatin c and blood urea nitrogen values showed some relation with elasticity, the study did not show any significant correlation between shear wave elastography values and laboratory tests in pediatric transplanted kidneys. Even though elastography of the renal transplant is feasible to conduct in pediatric population, it needs time to become a valuable non-invasive test in early detection of transplant disfunction. Purpose: The aim of our study was to describe imaging findings at diagnosis and follow-up to report outcomes according to the treatment and to identify early imaging prognostic markers. Material and methods: In this retrospective study, 17 neonates with unilateral (n=13) or bilateral (n=4) renal vein thrombosis were included. Results: Median age at diagnosis was 5.8 day (range 1 to 23 days). Enlarged kidneys were present prenataly in 3/17 (18%) neonates. Postnatal symptoms were present in all neonates with enlarged kidney (10/17, 58%), thombocytopenia (10/17, 58%) hematuria (9/17, 52%). The classical triad was present in 3 neonates and 10 neonates had at least 2 clinical signs. Risk factors were found in all neonates except 2: perinatal asphyxia (n=7), diabetic mother (n=1), hypotrophy/preterm birth (n=5), prothrombotic conditions (n=4). Diagnosis was performed on ultrasound in all cases. Thrombosis was on the left side in 55% of cases. A venous thrombus was visualized in 16/21 (76%) kidneys with an extension to the inferior vena cava in 13/17 (76%) cases. Enlarged kidney was present in 15/21 (71%) with decreased cortico medullary differentiation in 16/21 (76%), vascular streaks in 11/21 (52%) and heterogeneous cortex in 4/21 (19%). On doppler imaging, venous flow was abnormal in 16/20 (80%). Overall renal flow was decreased or absent in 8/10 (80%). A reverse flow or elevated resistive index was present in 10/18 (55%). Thrombolytic treatment was given in 3 neonates with bilateral thrombosis. Two of them presented brain hemorrhagic complications. Mean follow up was 7 years (range 1 to 17). The rate of repermeabilization and renal atrophy was similar in both treatment groups. After thrombolysis, we observed 4/6 (67%) repermeabilization and 4/6 (67%) renal atrophy compared to 10/15 (69%) repermeabilization and 10/15 (66%) renal atrophy in the anticoagulation group. One patient in the thrombolysis group presented chronic kidney disease and high blood pressure.

All kidneys with vascular streaks (n=11), profound hypoechoic and irregular pyramids (n=7), heterogeneous cortex (n=4) or decreased renal flow (n=7) progressed to renal atrophy. Conclusion: Neonatal renal vein thrombosis is a severe disease leading to renal sequelae in the majority of patients. Vascular streaks, profound hypoechoic and irregular pyramids, heterogeneous cortex and decreased renal flow at diagnosis were associated with renal atrophy on follow up. In our cohort, thrombolytic treatment led to severe hemorrhagic complications without significant benefit on renal prognosis. Background: Many authors have reported that longer duration of symptoms reduces success rate for intussusception reduction. We investigate if this is a valid prognostic indicator and if it is statistically significant. In our institution, a tertiary referral center without an emergency department, children are transferred from other centers, often resulting in delayed presentation. Aim: To assess whether the potential delay in presentation to our institution has any impact on the rate of success of air enema reduction, and to identify whether there has been any variation in success rate over recent years. Material and methods: Retrospective analysis of all intussusceptions presenting to our institute over an eleven-year period (2011) (2012) (2013) (2014) (2015) (2016) (2017) (2018) (2019) (2020) (2021) . 108 fluoroscopic air enema intussusception reductions were performed during this time (100 total patients). Duration of symptoms and age at diagnosis were compared by Mann Whitney U test for continuous non-parametric variables, using regression analysis. Results: 100 patients satisfied the inclusion criteria and were included in the analysis. The median of duration of symptoms was 24 hours [IQR 24 -72] (range 4 -240 hours). The success rate of air enema was calculated. All factors were analyzed for impact on outcome using univariate analysis. Air enema was successful in 71 cases (65.7%). One child developed a perforation during the procedure (1%). The recurrence rate was 8%. Retrospectively we found that of the 29 failed reductions 17 patients required bowel resection. No difference in age was found between children with successfully reduced intussusception (median 10 months, IQR 7 -18) and those who experienced failed reduction (median 9 months, IQR 5 -17), p 0.680. No difference was found in duration of symptoms between children with successful outcome (median 24 hours, IQR 24 -72, range 4 -240) and those with failed reduction (median 32 hours, IQR 24 -72, range 7 -168), p 0.408. Conclusion: Our experience has not found a link between duration of symptoms and outcome of air enema intussusception reduction. Furthermore, it could not be used to identify poor prognostic factors. Intussusception reduction should be considered in all patients presenting with intussusception, irrespective of the duration of symptoms, if absolute contraindications are not present. Purpose: To evaluate the role of multi-sequential MRI in differentiating medullary osteonecrosis from osteomyelitis in children with sickle cell disease (SCD).

Material and Methods: All MRI scans done for children with SCD (ages 0-13 years) admitted for acute bone crisis between 2015-2021 were collected via PACS database search. Various MRI parameters were noted by 2 radiologists with experience in pediatric and musculoskeletal imaging, originally blinded to clinical data. Radiological diagnoses of osteomyelitis, osteonecrosis, or indeterminate were provided. Electronic medical records were reviewed to obtain clinical diagnoses of either osteomyelitis or osteonecrosis based on the censuses of hematology, infectious diseases, and orthopedic surgery. Kappa test was used for clinical/ radiological agreement. Fisher's exact test was used to evaluate statistically significant MRI parameters in relation to the radiological and clinical diagnoses of osteomyelitis or osteonecrosis (statistical significance defined at P < 0.05). Results: A total of 50 radiological observations were gathered, and 42 were included (8 were excluded due to lack of imaging findings or diagnosis of epiphyseal AVN). Agreement between clinical and radiological diagnoses was fair (Kappa = 0.52). MRI parameters that show statistical significance based on both clinical and radiological diagnoses included the presence of cortical defect (P = 0.0001 and 0.0094, respectively) and soft tissue inflammation (P = 0.0253 and 0.0000, respectively). Conclusion: MRI can reliably differentiate osteomyelitis from medullary osteonecrosis in children with SCD, based on the presence of cortical defects and soft tissue inflammation. Other parameters, including enhancement pattern, can be of supplemental value, but are not reliable. Purpose: Approximately 20-50% of children with juvenile idiopathic arthritis (JIA) have hip involvement within 6 years of diagnosis (1-2). To date, no child-specific hip MRI scoring system has been established (3-9). We aimed to introduce a novel MRI-based score for active and chronic changes in children with JIA and to examine its inter-and intraobserver variability in a multicenter study. Materials and methods: We reviewed a set of 60 MRIs from 60 children with JIA hip involvement across two Italian centers. We assessed findings of (1) active changes (2) chronic changes and (3) growth abnormalities and secondary post inflammatory changes, according to a pre-defined scoring system. All MRIs were scored independently by two pairs of radiologists, followed by a repeat score by one of the pairs after a minimum of three weeks. Kappa statistics was used to analyze inter-and intraobserver agreement for categorical variables, while a Bland Altman approach was used to test continuous variables. Results: There was a good agreement for grading overall impression of inflammation for the same observer (kappa 0.7) and between observers (kappa 0.6). Synovial enhancement showed a good intra-observer variability (kappa 0.7-0.8) while the inter-observer variability was moderate (kappa 0.4-0.5). The agreement for subjective evaluation of synovial thickening was good to very good for the same observer (kappa 0.8-0.9) and moderate between observers (kappa 0.4-0.5). Grading bone marrow oedema performed well for the same observer (kappa 0.7 for all locations), however the kappa values between observers were poor. There was a good intra-observer as well as inter-observer concordance for grading acetabular erosions (kappa 0.6-0.7). The agreement for grading active erosions on the femoral head was good to excellent, both for the same, and between observers. Measurements of joint space height, CCD, femoral neck-head length, femoral width and trochanteric distance were imprecise with wide 95% limits of agreement (LOA). Conclusion: We found a good reproducibility in a large number of the proposed MRIs variables for both active and chronic features, the most interesting being the overall synovial inflammation and the evaluation of active erosions. We suggest that the more reproducible variables could be included for clinical use in future studies assessing clinical validity and long-term patient outcomes. Introduction: Slipped-capital-femoral-epiphyses (SCFE) is a common pediatric hip disease. Diagnosis of SCFE is based on slip angle (SA) measurement. We performed preoperative MRI for evaluation of severity of slip deformities and for surgical planning. Therefore, we report on measurements of SA on preoperative MRI and lateral radiographs of SCFE patients. Methods: We performed a retrospective analysis involving 29 SCFE patients (31 hips, [2015] [2016] [2017] [2018] [2019] [2020] [2021] . Exclusion criteria were SCFE patients with previous surgery, without preoperative MRI or with insufficient radiographs. Mean age was 13±2 years, twelve patients had chronic and 13 patients had acute on chronic SCFE. The majority had stable SCFE. We evaluated SA on preoperative lateral radiographs and on radial protondensity MRI images of the MRI. Radial images were oriented along the axis of the femoral neck. The maximum SA on MRI was compared to SA measured on lateral radiograph. ICC for maximum SA on MRI was good for two readers. SA was measured on posterior clock positions on MRI. All SCFE patients underwent surgical treatment. The control group consisted of 30 hips (17 patients; mean age 17±2 years) of asymptomatic volunteers. Results: Mean SA on preoperative lateral radiograph was 40±18°, SA on MRI was 48±17°. SA on MRI was significantly (p<0.001) increased posterior (9 o'clock, 43±18°) compared to superior (12 o'clock, 12±6°) and compared to control group. Measurement of SA on MRI changed diagnosis of 4 patients with severe SCFE, six patients had severe SCFE (SA>60°) on radiograph and ten patients had severe SCFE (SA>60°) on MRI. Diagnosis changed of 10 patients with moderate SCFE, ten patients with mild SCFE (SA<30°) had moderate SCFE (SA 30-60°) on MRI. Posterior and posterior-superior (9 o'clock and 10 o'clock) slip direction was most common (29 of 31hips, 94%). Whereas none of the hips of the control group (0/30; 0%) had (p<0.001) posterior slip. infants (16 females and 3 males) with developmental dysplasia of the hip, classified as type II C or more according to Graf classification, were prospectively enrolled. Between them 13 had a bilateral DDH, for a total of 32 affected hips. All the patients underwent closed reduction and hip casting and had an MR examination after each casting. A total of 37 MR hip scans performed without sedation nor contrast medium were obtained and then examined by a paediatric radiologist. RESULTS: The MR examinations detected the position of the femoral heads in their acetabular cavities: 31 MR scans (84%) revealed well centered heads while 6 MR scans (16%) showed head luxation that needed new reduction and casting. 11/37 (30%) MR scans showed the presence of an hypertrophic acetabular labrum, of which 5/37 (16%) displayed a labral introflexion. 8/37 MR examinations revealed the presence of joint effusion (22%). Only 1/19 patients developed a hypertrophic round ligament, as well as 1/19 patients showed the fibrofatty pulvinar hypertrophy and the presence of proliferative fibrous tissue in the joint cavity, the so called "limbus". CONCLUSIONS: Although the limitations of this study, above all the low number of the patients enrolled and the analysis of the images made by only one paediatric radiologist, it is clear that the MRI is useful to assess the position of the femoral head after closed reduction without ionizing radiations (X-ray and CT scan). Moreover, the MR can easily study also the extra-osseous structures of the hip joint as the morphology and signal of the labrum, the pulvinar and the round ligament, in order to help surgeons to choose the appropriate treatment strategies.

Céline Habre 1 , Alexia Dabadie 2 , Anderson D Loundou 2 , Jean-Bruno Banos 2 , Catherine Desvignes 2 , Harmony Pico 2 , Audrey Aschero 2 , Nathalie Colavolpe 2 , Charlotte Seiler 2 , Corinne Bouvier 2 , Emilie Peltier 2 , Jean-Claude Gentet 2 , Christiane Baunin 2 , Pascal Auquier 2 , Philippe Petit 2 1. Hôpitaux Universitaires de Genève, Geneva, Switzerland 2. Assistance Publique -Hôpitaux de Marseille, Marseille, France

Background: Diffusion-weighted imaging (DWI) has been described to correlate with tumoural necrosis in response to preoperative chemotherapy for osteosarcoma. Objective: To assess the accuracy of DWI in evaluating the response to neoadjuvant chemotherapy at the mid-course treatment of long-bone osteosarcoma and in predicting survival. Materials and methods: We conducted a prospective single-center study over a continuous period of 11 years. Consecutive patients younger than 20 years treated with a neoadjuvant regimen for peripheral conventional osteosarcoma were eligible for inclusion. Magnetic resonance imaging (MRI) with DWI was performed at diagnosis, and mid and end-course chemotherapy with mean apparent diffusion coefficients (ADC) calculated at each time point. A percentage less than or equal to 10% of the viable residual tissue at the histological analysis of the surgical specimen was defined as a good responder to chemotherapy. Survival comparisons were calculated using the Kaplan-Meier method. Uni-and multivariate analyses with ADC change were performed by Cox modelling. This is an expansion and update of our previous work. Results: Twenty-six patients between the ages of 4.8 and 19.6 years were included, of whom 14 were good responders. At midcourse chemotherapy, good responders had significantly higher mean ADC values (P=0.046) and a higher increase in ADC (P=0.015) than poor responders. The ADC change from diagnosis to mid-course MRI did not appear to be a prognosticator of survival and did not impact survival rates of both groups. Conclusion: DWI at mid-course preoperative chemotherapy for osteosarcoma should be considered to evaluate the degree of histological necrosis and to predict survival. The anticipation of a response to neoadjuvant treatment by DWI may have potential implications on preoperative management.

Till Lerch 1 , Tilman Kaim 1 , Simon Steppacher 1 , Florian Schmaranzer 1 , Jasmin D. Busch 1 , Kai Ziebarth 1 1. Inselspital Bern, Bern, Switzerland Introduction: Slipped capital femoral epiphyses (SCFE) is a common pediatric hip disease. SCFE was associated with femoral retroversion but femoral version (FV) has rarely been described in SCFE patients. Therefore, we report mean femoral neck version, mean FV and prevalence of femoral retroversion for SCFE patients. Methods: A retrospective study evaluating preoperative hip MRI involving 38 hips (20 patients) was performed. Twenty SCFE patients (20 SCFE hips and 18 contralateral hips, 10-16 years of age) without previous surgeries were evaluated. FV was measured using the Murphy method on rapid bilateral T1 VIBE Dixon MRI (01/2017-12/2021) Water-based images of the pelvis and knee. FV was compared to the contralateral side. All SCFE patients were treated surgically. Fifteen SCFE hips presented with moderate or severe slips and were treated with open surgery. Results: Mean FV of SCFE patients (1±17°) was significantly (p<0.001) lower compared to contralateral side (17±14°). FV of SCFE patients had a wider range from -42 to 35°(range of 77°) compared to contralateral side (-3 to 44°). Eight SCFE patients (40%) had femoral retroversion (FV<0°), five of them had severe slips and two had mild slips. One patient (6%) of the contralateral side had femoral retroversion. Side-to-side difference of FV was higher for SCFE patients (18±15°). Conclusion: Preoperative MRI for SCFE patients showed femoral retroversion in more than one third of the patients and showed asymmetrically lower FV compared to contralateral side. FV angles ranged widely and SCFE does not necessarily lead to femoral retroversion. Femoral retroversion was mainly prevalent in severe SCFE but also in mild SCFE. Adding FV to the diagnostic workup of children with SCFE could help for diagnosis of femoral retroversion. Patient-specific analysis of FV may better inform surgeons to decide when to use isolated offset correction Background: Post-mortem fetal MRI is on the rise since it was proven to be a good alternative to conventional autopsy. Similarly, to diagnostic use, MRI can be used to assess fetal maceration. Since the fetal brain is sensitive to post-mortem changes, extensive tissue fixation is required for macroscopic and microscopic assessment. Estimation of brain maceration on MRI, prior to autopsy, provides potential to optimize the histopathological resources. Objective: The purpose of this study is to develop a reproducible brainspecific maceration score on post-mortem MRI that correlates well with the signs of brain maceration on fetal autopsy. Materials and Methods: This study included data collected between February 2016 and December 2020, in a tertiary center serving as a referral center for congenital malformations. Scans were performed on available 3T or 1.5T MRI systems with the smallest possible coil for the fetal size. Maceration was scored on MRI with a numerical severity scale, for our brain-specific score (including fluid distribution, ventricular lining, congestion, corpus callosum, deep grey matter integrity, brain stem, cerebellum and eyes) and the whole-body score of Montaldo. Additionally, maceration was scored on histopathology with a categorical severity scale. Both the brain-specific and the whole-body maceration scoring systems on imaging were correlated with the histopathological maceration category. Scoring was performed by two observers (novice and expert PM MRI reader). Intra-observer and inter-observer agreements were tested for the brain-specific brain maceration score. Results: 79 post-mortem fetal MRI-scans followed by autopsy were included. The proposed brain-specific maceration score correlates well with fetal brain maceration seen at autopsy (Tau = 0.690), compared to a poorer correlation of the whole-body method (Tau = 0.452). No significant effect on de brain-specific maceration score was observed by the different time intervals (gestation, feticide-MRI, MRI-autopsy and feticide-autopsy). The intra-and interobserver agreement was excellent (correlation coefficients of respectively 0.943 and 0.864). Conclusion: We present a brain-specific post-mortem MRI maceration score that correlates well with the degree of fetal brain maceration seen at histopathological exam. In our hands this score has an excellent reproducibility.

Antoine MARTIN-CHAMPETIER 1 , Alexia DABADIE 1 , Kathia CHAUMOITRE 1 , Philippe PETIT 1 1. APHM, Marseille, France

Purpose: In France, the current recommendation is to perform a routine abdominopelvic ultrasound in any child under two years of age who is suspected to have been abused. We retrospectively studied the relevance of this practice in our center over the past fifteen years. Materials and methods: This was a descriptive, retrospective study of all children under two years of age who had been subject to suspected abuse. Abdominal images and reports were reviewed and cross-referenced with possible clinical and biological signs. Results: Four hundred and five children were included between 2006 and 2020, of whom 296 underwent abdominal imaging (2 initial abdominopelvic CT scans, 4 ultrasounds followed by CT scans, and 290 ultrasounds alone). Four examinations revealed traumatic abnormalities related to abuse. These four children all had clinical or biological anomalies. In the absence of clinical or biological signs, no imagery showed any abnormality related to abuse. Conclusion: In this population, systematic abdominopelvic ultrasound in children under 2 years of age who were suspected to have been abused did not show any abuse-related lesions in the absence of clinical and/or biological signs. Purpose: Well-appearing infants with suspected physical abuse are at risk for clinically occult intracranial injuries. Identifying these injuries can inform clinical care and may influence efforts to protect the infant. Research over the past 2 decades, largely from single-center studies, has revealed widely varying neuroimaging yields (i.e., rates of positivity) in identification of occult head injury. We sought to describe neuroimaging yield using CAPNET, a multicenter child abuse research network that includes data from 8 geographically diverse child protection teams in the US. Material and Methods: Infants undergoing subspecialty abuse evaluation between 02/2021-08/2021 were identified in CAPNET. Infants <12 months evaluated by a child abuse pediatrician due to concern for physical abuse who underwent both skeletal survey and neuroimaging (CT, standard or fast MRI) were included. Infants were excluded if an intracranial injury was the injury which prompted concern for abuse or if they had one of the following signs/symptoms of potential clinically-apparent head trauma: scalp swelling/bruising, cardiorespiratory collapse, BRUE, skull fracture, irritability, lethargy, unresponsiveness, alteration in consciousness, macrocephaly, bulging fontanelle, seizure, limpness, posturing, intubation, abnormal GCS, or other neurologic sign/symptom). Our outcome was intracranial injury (hemorrhage, extra-axial collection, or parenchymal injury). Demographics, clinical presentation, and neuroimaging findings are reported. We tested for association between age <6 months and intracranial injury using a fisher exact test. Results and Conclusions: Of 373 infant evaluations without signs/ symptoms of head trauma, 250 (67.0%) underwent neuroimaging. The majority (71.2%) were <6 months. Injuries prompting abuse evaluation were most frequently cutaneous (46.4%) or fracture (30.4%); 16.8% had no presenting injury. Head CT was performed in 72.0%, MRI in 18.4%, and fast MRI in 15.2%. Twelve (4.8%) had intracranial injury, which was most frequently subdural hematoma (N=7). Intracranial injury occurred more frequently in infants <6 months (6.2%) than those 6 months or older (1.4%), but was not significant (p=0.19). Our results suggest intracranial injuries occur in a small minority of well-appearing infants with concern for abuse. Further research is needed to develop evidence-based strategies to clarify which infants warrant screening neuroimaging. Purpose: Subdural haematoma is significantly associated with abusive head trauma in young children, and it is also believed that benign enlargement of the subarachnoid spaces predisposes to subdural bleeding. We aimed at examining the prevalence of clinically silent brain haemorrhage in otherwise healthy children with increasing head circumference.

Material and method: During 2021 to 2024, all children between 2 and 12 months of age seen at the outpatient clinics at five of the Norwegian University hospitals, due to an increasing head circumference (crossing 2 centiles), will be invited to participate in the study (n=150). Exclusion criteria: babies born prematurely <37 gestational weeks, and children with known, medical conditions that may involve the central nervous system. Data on maternal conditions/medication, delivery (vaginal, section), intrauterine posture (cephalic, breech), the child's age, sex, birth weight/length/head circumference and previous injury will be collected from the medical notes, together with information on previous visits to the A&E department. All children will be examined by a named, experienced paediatrician at each of the study sites, and the following will be registered: ethnicity (white-non-white), developmental issues, symptoms related to increased intracranial pressure, head circumference, weight and length. In addition, the head circumferences of both parents will be measured. All children will have a head ultrasound, followed by a short, un-sedated head MRI within a period of 3 days, according to predefined protocols. The MRI protocol is a limited rapid MRI brain protocol with scan time < 4 minutes, as suggested by Berger et al., including the following sequences: axial T2-weighted ultrafast spin echo, axial T2-weighted gradient echo, coronal T2-FLAIR ultrafast spin echo and a sagittal T1weighted gradient echo. Results: A total of 22 children (10 females (45%)) have been examined this far, mean age 6 months (SD = 2,6 months). 20 of the examinations were judged to be of adequate quality for analysis including axial T2-weighted ultrafast spin echo and axial T2-weighted gradient echo of adequate quality. Mean depth of the subarachnoid space was 4,4 mm (SD 1,8 mm), while the mean depth of the lateral ventricle (left side) was 5,6 mm (SD 3,3 mm). No hemorrhage or hemosiderin products were seen on MRI. Conclusions: Hitherto, none of the infants examined for increasing head circumference beyond 2 centiles had a bleed or blood products. Purpose: The standard acquisition of lateral radiographs of the appendicular skeleton are a new addition to the UK national guidance for imaging in suspected physical abuse (SPA) since 2017 [1] . This is despite a paucity of scientific evidence and variation in standard practice internationally where lateral radiographs are only acquired at the discretion of the radiologist [2]. Our objective was to investigate the additional diagnostic yield and reporter confidence of lateral radiographs in SPA. Methods: A single center, retrospective review of a 3-year period (October 2017-Novemver 2020) was conducted to retrieve all initial, complete skeletal surveys performed for SPA in children under 30 months. Two consultant paediatric radiologists, blinded to indication and report, were asked to review the frontal projection of appendicular radiographs, followed by the frontal and lateral radiographs. The readers noted the presence or absence of a fracture and assigned a confidence level (0-5) on each occasion. Frequency of fracture detection and confidence using single and two-view reads were compared to original report and between readers (paired t-test). Results: One hundred and thirty-eight children's skeletal surveys met inclusion criteria, mean age 8 months, 75/138 (54%) male, 109/138 (79%) post-mortem. There were 16 appendicular fractures total in 9 individual cases. Radiologist 1 and 2 identified 15/16 fractures (94%) and 14/ 16 (88%), respectively. Of these, 14/15 (93%) and 13/14 (93%) were identified on the frontal view alone, respectively. Two fractures not identified on frontal view were a radial metaphyseal fracture, where the wrist was not captured on the frontal hand view, and a tibial metaphyseal fracture, in which there was disagreement as to whether this represented a fracture at all. There was a significant increase (p<0.05) in confidence level for both radiologists where the images were normal, but not when a fracture was present. Conclusion: The majority of corner metaphyseal fractures were visible on frontal projection radiographs alone, with the lateral view adding diagnostic value in one case where the frontal image was inadequate, and one challenging case where there was uncertainty about the presence of a fracture. The lateral views did improve radiologist confidence when the joints were normal. Trials with larger patient numbers will help substantiate these findings. Purpose: Osteogenesis imperfecta (OI) as a cause for metaphyseal fractures in infants and young children in whom abuse is suspected is a controversial topic. Some authors (e.g., Astley 1979 , Paterson 1987 , Gahagan 1991 have reported OI as a cause for "metaphyseal" fractures but these fractures were poorly illustrated in publications and appear to be "metadiaphyseal". To date, there have been no large-scale studies investigating this topic. Our study aims to assess the prevalence of "metaphyseal" fractures in children with OI aged 0-2 years. Material and Methods: This is a retrospective study of radiographs from 1st January 2010 to 31st December 2021 of children aged 0-2 years attending the OI clinic. A list of OI patients was obtained from paediatricians and a search was done on PACS for radiographs. Images were reviewed by a consultant with over 20 years' experience and the reports and images were reviewed by a medical student. Sites, types of fractures and other features of OI like Wormian bones were recorded. Descriptive statistics will be used to analyze the results. Results: The total number of patients with OI was 536 of which 312 were excluded because they were either over 2 years of age on 1 st January 2010 or had no radiographs or no long bone radiographs below the age of two. Therefore 118 patients (with3394 radiographs, 2080 < 1 year and 1314 1-2 years) are included. Data collection and analysis is ongoing, with review available for 40 (34%) patients (1130 radiographs) to date. Of these 40 patients, 7 have type I OI, 15 type III, 6 type IV and 5 type V. Type of OI has not been ascertained for 7 patients. There have been no patients with metaphyseal fractures while 20 patients (50%) have had at least one metadiaphyseal fracture. Concerning fractures at other sites, 22 (55%) have rib fractures, 12 (30%) vertebral, 31 (77.5%) shaft, 5 (12.5%) clavicular, 1 (2.5%) scapula and 0 with skull fractures. Wormian bones were present in 27 (67.5%). Fracture distribution between those with and without Wormian bones is similar. Conclusions: Preliminary results suggest children with OI do not get the typical metaphyseal fractures that are associated with abuse. Distinction should be made between metaphyseal and metadiaphyseal fractures to avoid confusion amongst non-radiologists. Purpose: To implement and evaluate a feature that automatically selects exposure settings by patient size for head CT in children.

Material and Methods: Protocols applying a feature that automatically selects kV and mAs based on attenuation information from scout images were implemented for paediatric axial volumetric head CT on a 256-slice scanner. Radiation dose (CTDIvol) and image quality were compared between 79 consecutive studies obtained with auto prescription protocols and 68 studies obtained previously with age-based protocols in 147 patients aged 1 day to 17.7 years (median age 6 years). Image quality was assessed by signal to noise ratio (SNR) of the basal ganglia, contrast to noise ratio (CNR) between gray and white matter and rated on a 4-grade Likert scale as 1 -unacceptable, 2 -limited, 3 -adequate and 4 -higher than needed. Comparisons were made with non-parametric tests. Results: Radiation dose from auto prescription studies was lower (CTDIvol 16.6 ± 4.0 mGy) than from age-based protocols (CTDIvol 22.2 ± 7.6 mGy) providing lower SNR (8.9 ± 2.1 versus 11.9 ± 3.5) and lower CNR (1.5 ± 0.6 versus 1.9 ± 0.9) but still achieving adequate diagnostic image quality (mean overall image quality by all readers of 3.0 ± 0.2 versus 2.8 ± 0.2). Conclusion: Attenuation-based auto prescription of scan settings allows for balanced radiation dose and image quality in head CT across the paediatric size range resulting in lower dose than with age-based protocols We used a commercial neonatal chest phantom with weight class 1-2 kg for Visual Grading Analysis (VGA) of clinical images, which were acquired with different filter, kV, and mAs settings via CR needle and DR CsI detectors with standard image post-processing. VGA evaluation of 13 criteria in total, including European criteria, was performed by three radiologists. Intra-Class Correlations (ICC) were used to determine Inter-Reader and Intra-Reader Agreement among the radiologists. VGA Score (VGAS) and Dose Area Product (DAP) values were used to calculate dose levels for good image quality. After manual image registration, Artificial Intelligence (AI) was used to determine Signal-to-Noise Ratio (SNR), Contrast-to-Noise Ratio (CNR), and signal profiles at the same regions of VGA. AI results were compared to VGAS by Inter-Reader Agreement. Results: Technical data (IQFinv) shows no significant difference between the two detectors (p>0.05). VGAS of neonatal phantom post-processed images shows no significant difference at the same DAP level between the two detectors, or when using standard pediatric filtering, i.e. 3.5 mm Al + 0.1 mm Cu, instead of minimal filtering of 2. 5 Conclusions: According to our evaluation by visual assessment and AI, there is no significant difference between CR needle and DR CsI technology in neonatal chest radiography. Standard pediatric filtering shows no reduced image quality at the same DAP level compared to minimal filtering. We propose different parameters (e.g. 57 kV/1.6 mAs, 77 kV/ 0.8 mAs; total filter 3.5 mm Al + 0.1 mm Cu) and respective dose levels (0.010, 0.012 mSv ED) for optimal image acquisition in neonates.

Monica Miranda Schaeubinger 1 , Larsen Ethan 1 , Raymond Sze 1 1 Children's Hospital of Philadelphia, Philadelphia, United States Purpose: Our department registers different types of imaging errors in digital radiography (DR) through an internal safety reporting system (SRS). Through this, the need to decrease incident errors in DR was identified. Following the Realizing Improvement Through Team Empowerment Methodology, a quality improvement project to reduce avoidable errors started in 2020. Materials and Methods: A goal was set to reduce median days since last avoidable error from 4.6 to 7 days by the end of six months. A fishbone diagram identified points in the workflow that lead to most errors, along with their corresponding key drivers. Seven interventions were implemented and included: proper timeout checklists, EHR available uniformly on different machines, and implementation of disposable markers among other interventions. Results: During the first six months, a decrease in laterality errors was seen. However, a sustainability plan was implemented for continuous improvement over the year 2021, which included building an operations dashboard using Qliksense. While building the dashboard, a new classification system was created for DR errors, which referred to avoidable errors and 6 points in the process where errors were occurring (the order, the patient, the demographics, the exam, the accession number, and the laterality). Errors were further defined into pre-cursor events, which are good catches by the tech before images are sent to PACS, and harm events, which are caught later in the workflow where the error reaches the patient. These categories align with the Enterprise level HARM prevention work and led to a revision in metrics to reflect the days since last event of harm. With these additional changes, we gained the ability to identify where in the process the errors occur, and which countermeasure would prevent them from happening again. In addition, the Just Culture practices were renewed. When harm events are reported via the SRS, the follow up aims to identify the process issues without placing blame on the tech for the error. With the involvement of the Quality Improvement team and DR technicians, the department recently celebrated 180 days without harm in DR. Conclusions: Meaningful improvement can be attained in Radiology by continuously adapting to results, improving strategies, promoting sustainable interventions, and empowering frontline personnel. Improvement can be achieved, and harm to the patient can be further minimized.

Material and Methods: An automatic in-house 2D lung segmentation model based on a 2D Feature Pyramid Network with ResNext blocks in the encoder, was trained and validated on publicly available datasets containing human CTs with reference lung segmentations [1] . The model's performance on pediatric CT scans was evaluated on an opensource dataset of 359 pediatric chest/abdomen/pelvic CT exams [2], containing manual lung segmentations for all cases. These segmentations were compared with the automatic ones by computing the Dice similarity coefficient (DSC) and relative absolute volume difference (ravd), along with qualitative visual inspection. Results and Conclusions: The dataset presents a variety of pediatric cases based upon routine clinical indications. From the 359 scans, 12 were discarded due to missing slices or the absence of lungs in the scanned volume. The age of the remaining 347 pediatric patients ranges from 5 days to 16 years, with a mean age of 7, and a near equal distribution of male and female exists. The comparison of the model predictions with their respective manual segmentation resulted in a median DSC of 0.95 with an interquartile range of 0.06 and a median ravd of 8.11% with an interquartile range of 14.10%. DSC scores were also computed for different age subgroups (0-2, 3-4, 5-7, 8-11, 12-16) with comparable performances (median DSC > 0.9). Visual evaluation of the outlying low performance cases highlighted several limitations in the manual segmentations provided in the open-source dataset. The model showed good performance also in the presence of lung abnormalities such as consolidation, ground glass opacities and lung tumors, including them correctly in the lung mask. However, the model encountered some difficulties in exceptionally severe pathological cases presenting either pleural effusion, deflated lung lobes or abdominal air. This study proved the generalizability of the DL lung segmentation model to pediatric CT scans, irrespective of age and the presence of several common lung pathologies. Purpose: The aim of our study was to assess the concordance among the bone age evaluated by a machine learning system and the Greulich and Pyle method. Materials and Methods: We enrolled 181 people (95 males, 86 females) aged between 1 and 16 years old, from the database of two hospitals, one main paediatric regional referral centre and a main general hospital in Palermo. We used the Greulich and Pyle method and an AI software to analyze each x-ray image and compute bone age and standard deviation, corrected for sex and age. Results: Compared to the true age, AI and GP gave estimates, respectively, positively (mean zAI= 0.28 and SDAI= 2.68) and negatively (mean zGP= -0.68and SDAI= 3.18) biased. However, the disagreement between AI and GP was not statistically significant (zAI-zGP=0.93, 95%CI= [-5.84; 7.71]) and there was not any systematic trend in the difference between two assessments that could be related to the estimated bone age. Mean time for AI analysis was 4.85 sec, for standard GP ranges between 18.56 to 21.39 sec.

Conclusions: Both AI and GP correctly estimate the true chronological age; however, the measurements made by AI were faster and closer one to another rather than the GP method, so that we concluded that the AI made faster and more accurate evaluations.

Toan Nguyen 1 , Aloïs Pourchot 2 , Vincent Marty 2 , Jeanne Ventre 2 , Nor-Eddine Regnard 2,3 1. Hôpital Armand Trousseau, Paris, France 2. Gleamer, Paris, France 3. Réseau Imagerie Sud Francilien, Lieusaint, France

Purpose: Bone age assessment is a routine procedure in pediatric radiology, for which the Greulich and Pyle atlas [1] is mostly used. The aim of this study is to evaluate the performance of a deep learning algorithm to predict bone age. Material and Methods: We collected 162 frontal left and right hand views of children aged 5 to 19 of which 97 were boys and 65 were girls from an internal existing test set coming from four European radiology departments. Images with a truncated wrist (N=6) preventing bone age estimation were excluded from the dataset. The gold standard was established by a senior board-certified pediatric radiologist who assessed the bone age based on the Greulich and Pyle atlas knowing the sex and chronological age of the patient but blinded to the algorithm results. The deep learning algorithm was engineered to predict the bone age based on a public dataset from RSNA. It was trained on 12,600 frontal left and right hand views, tested on 200 and validated on 1,000. Performance of the deep learning algorithm was assessed by the mean average error between the predicted bone age and the Greulich and Pyle bone age. Confidence intervals (CI) were calculated using bootstrap samples. The Pearson coefficient was used to estimate the correlation between predicted and true bone age. Results: A total of 156 patients were included in the study of which 93 were boys with mean chronological age 12 ± 3.7 years and 63 were girls with mean chronological age 9.8 ± 3.6 years. The mean average error was 0.699 years (95% confidence interval: Background: The radiological determination of bone age (BA) from a left-hand x-ray continues to be the reference standard for skeletal maturity assessment related to short or long stature, premature or delayed puberty, and underlying conditions. Artificial intelligence (AI) algorithms are becoming more prevalent due to the subjectivity and time-consuming nature of BA assessment. Objective: In this study we evaluate the agreement between AI and expert readers for BA assessment according to the Greulich & Pyle method. Methods: Radiographs of 342 patients were analyzed retrospectively (178 males, 165 females aged 2 to 16 years). Sampling was performed across multiple sites in the USA associated with Washington University in St. Louis (WUSTL) School of Medicine. Three board certified pediatric radiologists made blind reads of BA using the Greulich & Pyle (GP) method independently, and an AI-software was subsequently used to estimate BA from the same images. Agreement of AI with readers was assessed based on comparison of Bland-Altman limits of agreement (LOA), orthogonal linear regression and interchangeability. Results and Findings: Bland-Altman assessment displayed a mean difference between readers and AI to be -0.72 (-1.46 LCI; 0.02 UCI) months. Using orthogonal linear regression, the slope of agreement between readers and AI software was reported to be 1.02 (1.00 LCI, 1.03 UCI). No proportional bias was observed. The square root of the absolute value of the equivalence index of the AI software compared to assessments made by readers was observed to be -5.8 months. This indicates that the AI software is interchangeable with expert readers. Conclusion: A fully automated AI software shows agreement with expert readers in BA assessment on a multiple site cohort of US children and adolescents, suggesting AI integration into the radiology workflow is possible and could lead to more efficient bone age reading. Purpose: The number of conventional X-ray examinations in paediatric emergency departments is constantly increasing, which can lead to avoidable errors in interpretation by the radiologist. The use of artificial intelligence (AI) could improve the interpretation workflow by prioritising pathological radiographs as well as providing assistance in fracture detection. Material and methods: A cohort of 300 anonymized radiographs performed for peripheral skeletal fracture detection in patients aged 2 to 21 years was retrospectively collected. The gold standard was established for each examination after an independent review by two radiologists expert in musculoskeletal imaging. In case of disagreement, a consensual review with a third expert radiologist was performed. The 300 examinations included 60 exams per bodypart (hand/wrist, arm/elbow, shoulder, leg/ knee, foot/ankle), half of which presented at least one fracture. All radiographs were then read by 3 senior pediatric radiologists and 5 radiology residents in training between the 2nd and 4th year of residency. The Xrays were read without the help of AI and immediately after with the AI help. Sensitivity and specificity for each group of radiologists were calculated without and with the help of AI. The study was approved by an IRB n°CRM-2109-203. Results: The mean sensitivity for all groups was 73.3% without AI, it increased significantly by 9. 5 Background: Hereditary retinoblastoma (RB) patients are at high risk for second primary tumours (SPT), especially in the head and neck area when primary conservative treatments had included external beam radiotherapy (EBR). These SPT (mainly sarcomas) are associated with poor outcome. Early depiction might optimize their surgical removal and thereby improve both survival and residual visual function preservation. Objective: To assess the potential benefit of MRI for the early depiction of head & neck SPT in hereditary RB patients previously treated by EBR. Method: Prospective non-randomized national study (ClinicalTrial.gov: NCT03026998). Inclusion criteria were: hereditary RB (bilateral or multifocal or familial RB or identified germline RB1 alteration or 13q deletion), initial treatment including EBR, age at inclusion > 7 years and delay after EBR > 5 years. Patients formerly treated for malignant SPT were not eligible. The national database identified 173 eligible patients who were invited to participate. Included patients received a prescription to perform an MRI once a year using a standardized protocol (unenhanced T1, T2 with fat saturation or STIR or Dixon, DWI and FLAIR sequences covering the face, brain and upper neck). All examinations were prospectively collected and centrally reviewed. This interim report was obtained after 5 years (total study duration: 10 y). Results: 76 patients have been prospectively included so far. Mean age at inclusion was 20 y (range: 7-42 y). 161 MR examinations were reviewed. No malignant SPT has been depicted so far, while 5 other former patients (not included) developed symptomatic malignant head & neck SPT during this 5 years study period (3 facial bones sarcomas and 2 palpebral carcinomas). Meanwhile, central review depicted benign lesions in 16/76 (21%) patients: 5 meningiomas, 2 CNS low-grade tumours, 3 schwannomas, 4 presumed benign bone lesions (unchanged during follow-up), 1 pharyngeal fibrous polyp and 1 orbital inclusion cyst. Altogether, local treatment was eventually required in 6/16 (37.5%) patients. Adverse effects were not observed, especially no invasive diagnostic or treatment procedure related to MR depiction of benign conditions (i.e., overdiagnosis). Conclusion: This interim report provides neither evidence nor trend that MRI screening could allow early depiction of malignant SPT. Nevertheless, MRI screening in this specific cohort depicted various benign conditions in one fifth of the patients, including non-symptomatic CNS and peripheral nerve sheath tumours that justified local treatment in more than one third of these patients. Introduction: The aim of our 5 minute oral presentation is to share our experience of using intra-operative ultrasound and demonstrate its utility in real-time tumour delineation and tissue-sparing surgery. Oncological surgery in children can lead to lifelong complications, such as renal failure and infertility, however organ-sparing surgery carries a risk of incomplete tumour resection and escalated oncological treatments. Intraoperative ultrasound may enhance accurate identification of tumour margins as well as maximise organ preservation. Methods: All patients undergoing intra-operative ultrasounds performed within our institution were recorded prospectively from November 2016 to October 2021. Intra-operative ultrasounds were performed using a GE logiq S8 with 8-24MHz hockey stick probe or linear 8-15MHz probe. Cases were reviewed retrospectively. Pre-operative MRI and ultrasound findings, intra-operative ultrasound findings and post-resection histopathology results were recorded. Comparison images were obtained from pre-operative and intra-operative scans. Results/Key findings: 17 scans were performed during our study period. Nephron-sparing surgery achieved complete excision in 5/7 renal tumour cases, with 2 cases of nephrogenic rests extending to the resection margin which did not change oncological management. Testicular-preserving surgery achieved clear margins in 4/4 cases (paratesticular rhabdomyosarcoma, 2 epidermoid cysts and mature teratoma). Normal testicular tissue was identified for cryopreservation in cases of bilateral leukemic infiltration and juvenile granulosa cell tumour, and for oophorectomy in a case of disordered sexual differentiation. Clear margins were achieved after intra-operative delineation of a flank rhabdomyosarcoma, chest wall spindle cell tumour and myofibroblastic bladder tumour, with preservation of urinary continence for the latter. Conclusion: All patients who underwent intra-operative ultrasound for organ-preserving surgery achieved histopathological complete tumour resection. Whilst this study is currently limited by a lack of comparison cohort, it demonstrates the potential utility of intra-operative ultrasound in organ-preserving surgery. Intra-operative ultrasound is particularly valuable in delineating the deep extent of lesions or where the tumour is not identifiable by gross examination. Purpose: Most fat-containing soft-tissue tumors (STT) are benign. Imaging can identify those rare tumors at risk for malignancy, MRI being the reference method. Although clinico-radiologic guidelines are available for adults, diagnostic management of such tumors during childhood, adolescence and young adults (AYA) is still unclear. The aim of this study was to confirm the overall benignity of such tumors on a large cohort and to define the clinical and imaging features that warrant a biopsy. Material and Methods: A retrospective monocentric study was conducted on patients consecutively referred for STT to our Comprehensive Cancer Center through a 22-years period (1998-2020). Inclusion criteria were: age at diagnosis 0-25 years old, anatomical location in the soft tissues of the head and neck region, the trunk and the extremities, available imaging DICOM data, histologic confirmation of the tumor diagnosis and histologic identification of a fat-containing component within the tumor. Results: The database extraction identified 87 fat-containing tumors (10% of all STT), of whom 63 tumors had both clinical, histologic and imaging data available for review. Among them, 58 (92%) were benign tumors: 36 lipoblastomas and lipomas, 12 fibrous hamartomas of infancy (FHI), 5 lipofibromatoses (LF), 2 lipomas arborescens, 2 lipomatosis, and 1 spindle-cell lipoma. On cross-sectional imaging, all lipoblastomas and lipomas contained 25% of fat and presented with variable non-fatty components. All FHI and lipomas arborescens showed typical imaging features. Furthermore 5 patients (8%) were diagnosed with liposarcoma, all aged 12 years at diagnosis and 3/5 with a predisposing condition (Li-Fraumeni syndrome or previous anticancer treatment including radiotherapy). Myxoid zones on MRI were identified predominantly in malignant tumors (4/4) and in 3 of the 51 benign tumors. Factors significantly correlated with malignancy were age >10 years (p<0.001), predisposing condition (p<0.001), percentage of fat <25% (p=0.002) and presence of myxoid zones (p<0.001).

Conclusions: The majority of fat-containing STT in children and AYA may be classified as benign tumors based on imaging only, some histologic subtypes having pathognomonic clinico-radiologic features. Indication for biopsy should be limited to patients aged 10 years or more with either a predisposing condition or imaging features of the tumor demonstrating a low percentage of fat (< 25%) or the presence of myxoid zones. Purpose: Pediatric renal cell carcinoma (RCC) is a rare renal malignancy, with a different distribution of histological subtypes compared to its adult counterpart. Translocation-type RCC (MiT-RCC) is the most frequent subtype in children, in contrast to clear cell RCC (ccRCC) in adults. MRI is the preferred imaging modality for the assessment of pediatric renal tumors, and plays a potential role in the non-invasive discrimination of these entities. Previous literature has suggested imaging findings differ between RCC subtypes, however, studies focusing on MRIcharacteristics of pediatric RCC are limited. Therefore, this study aims to identify MRI-characteristics of RCC, focused on its presentation in children and young adolescents, through a single-center case series and literature review. Material and Methods: The diagnostic MRI-scans including diffusion weighted imaging (DWI) of six pediatric RCC patients were retrospectively assessed by two observers through structured case record forms which were subjected to analysis of inter-observer agreement. In addition, an extensive literature review was conducted in Pubmed, Embase and Cochrane, focusing on MRI-characteristics of RCC. Results: Six pediatric patients with a median age of 12 years (range 63-193 months) were included in this study. There were 2/6 patients with MiT-RCC and 2/6 with ccRCC. Five tumors had a hypo-intense appearance on T2-weighted (T2W) imaging, whereas 4/6 were iso-intense on T1-weighted (T1W) imaging. Also, 4/6 tumors showed well-defined margins, whereas other tumor characteristics were often inconsistent among patients. The reported median apparent diffusion coefficient (ADC)values on DWI ranged from 0.70-1.20*10 -3 mm 2 /s. Thirteen articles focusing on MRI-characteristics of MiT-RCC could be identified, in which a majority of the patients showed T2W hypo-intensity, similar to the reported MiT-RCC cases in our center. Furthermore, T1W hyperintensity was often reported in previous literature focusing on MiT-RCC, as well as an irregular growth pattern and limited diffusion restriction.

Conclusions: This study summarizes the MRI-characteristics of RCC, focusing on the pediatric-and young adolescent population, including a report of the diagnostic appearance of 6 unilateral tumors diagnosed in our center. The distinct presentation of pediatric RCC, and the limited available studies focusing on this patient population, make discrimination of RCC subtypes and differentiation from other pediatric renal tumor types difficult. This study stresses the importance of gaining specific knowledge of pediatric-and young adolescent RCC and focusing on innovative techniques. Purpose: Hepatic hemangiomas (HHs) are common benign infantile liver tumors that can nevertheless lead to serious complications. HHs present as focal, multifocal, or diffuse forms, but it is unknown whether initial ultrasound (US) features can predict the occurrence of complications. The purpose of this study was to analyze detailed US features of HHs and develop a predictive model of the risk of complications based on initial postnatal US features. Material and Methods: This was a single-center retrospective cohort study of clinical, biological, and imaging data of infants with HH presenting between 2000 and 2018 to a tertiary referral center. Patients were categorized as having either one complication of HH or not. Associations between initial postnatal US features and complications were analyzed separately for focal and multifocal/diffuse subtypes through univariate and multivariate logistic regression analyses, and stepwise logistic regression analysis was used to construct risk prediction models. Overall accuracy and area under the receiver operating curve (AUROC) were used to evaluate model discrimination. Results: Of 112 infants with a diagnosis of HH, 67 (60%) were focal, 32 (29%) were multifocal, and 13 (12%) were diffuse, with complication rates of 51%, 34%, and 92%, respectively, most commonly cardiac. The US characteristics were diverse, with variable size, echogenicity, and tumor vascularity. For focal forms, initial tumor volume >40 ml and hepatic artery peak systolic speed >100 cm/s had >70% sensitivity/ specificity to predict complications, and a model including these variables predicted complications with an accuracy of 82% and AUROC of 0.93. For multifocal/diffuse forms, a hepatic artery peak systolic speed above 115 cm/s had >70% sensitivity/specificity to predict complications, and a model including hepatic artery peak systolic speed predicted complications with an accuracy of 74% and AUROC of 0.86. Conclusions: The presenting US characteristics of pediatric HHs are diverse. The complications of HHs can be predicted using models based on initial postnatal US features, especially hepatic artery peak systolic speed and tumor volume for focal forms. Purpose: A new brain tumor entity occurring in early childhood characterized by a somatic BCL6 corepressor gene internal tandem duplication was recently described. The aim of this study was to describe the radiologic pattern of these tumors and to correlate this pattern with histopathologic findings. Material and Methods: This retrospective, noninterventional study included 10 children diagnosed with a central nervous system tumor, either by ribonucleic acid-sequencing analysis or deoxyribonucleic acid methylation analysis. Clinical, radiologic and histopathologic data were collected. A neuropathologist reviewed 9 tumor samples. Preoperative images were analyzed in consensus by 7 pediatric radiologists. Results: All tumors were relatively large (range: 4.7-9.2cm) intra-axial peripheral masses with well-defined borders and no peritumoral edema. All tumors showed mild and heterogeneous enhancement and marked restriction on DWI of the solid portions. Perfusion imaging showed a relatively lower CBF in the tumor than in the adjacent normal parenchyma. Nine out of 10 tumors showed areas of necrosis, with the presence of hemorrhage in 8/10 and calcifications in 4/7. Large intratumoral macroscopic veins were observed in 9/10 patients. No intracranial or spinal leptomeningeal dissemination was noted at diagnosis. Conclusions: Central nervous system tumors with a BCL6 corepressor gene internal tandem duplication present as large intra-axial peripheral masses with well-defined borders, no edema, restricted diffusion, weak contrast enhancement, frequent central necrosis, hemorrhage and calcifications, intratumoral veins and no leptomeningeal dissemination at the time of diagnosis. Knowledge of these imaging characteristics may aid in histologic, genomic and molecular profiling of brain tumors in young children. Methods & Materials: Patients with benign and malignant lesions treated with CT-guided cryoablation from January 2019 to January 2022 were reported. The procedure was performed with two cycles of 10 minutes each from -20°C to -40°C core temperature, followed by 5 minutes of thawing. Demographic data, radiological and clinical issues were collected. Results: Eight young adult, adolescent and pediatric patients (median age: 12.88 years; range 0.34-29.4 years) with diagnosis of benign or malignant lesions treated with CT-guided cryoablation were included in the study. Four patients had benign tumor (2 thoracic chondroid hamarthomas, 2 thoracic schwannoma, 1 abdominal ganglioneuroma), while four patients had pulmonary metastasis (2 Ewing sarcomas, 1 embryonal rhabdomyosarcoma and 1 clear-cell sarcoma of the foot (with three treated metastasis).

Ten total lesions were treated with CT-guided cryoablation. After median 5.47 months follow-up (range 0.77-18.20 months), seven lesions presented dimensional reduction (median 37.78%; range 9.99-60.47%). Three patients presented dimensional pseudo-progression (35.71%; range 27.49-38.22%): one schwannoma and one hamartoma; the other showed pulmonary sub-solid localization of embryonal rhabdomyosarcoma with ground-glass halo, differently from all other patients. No major or minor complications were reported. Conclusions: Percutaneous CT-guided cryoablation is a safe, minimally invasive technique, able to reduce both lesions and related symptoms, representing a supportive tool for multimodal treatments. Purpose: This work presents a deep learning algorithm used for the segmentation of renal parenchyma and collecting systems from MR urography. Methods and Materials: A fully connected neural network (NN) was developed that accepted as inputs a representative mean time series from a user selected region of parenchyma and collecting system as well as a time series from a voxel of interest. The output was classification of the voxel of interest as belonging to the parenchyma, collecting system or other tissue. The algorithm was trained on >100K observations from MR urography data (resolution 0.59 x 0.59 x 1.4 mm) acquired from 10 subjects. Ground truths were established from a further 12 subjects using a coronal 3D fast spin echo sequence (acquired resolution: 0.55 x 0.55 x 0.4 mm) reconstructed to 3 mm slice thickness and compared on a slice by slice basis with NN generated segmentations from MR urography data for the same subjects. Outliers originated due to differences between alignment of the ground truth and MR urography sequences and were identified and removed when exceeding an absolute Z-score of 3. Results: A total of 284 slices containing kidney parenchyma or collecting system segmentation were compared using Sorensen-Dice index. After removing outliers, mean Sorensen-Dice index for the parenchyma and collecting system was 0.78±0.10 and 0.62±0.22 respectively. The inter-reader agreement was very good with Bland-Altmann analysis showing a bias of 5%, and standard deviation of the difference of 7%. The representative mean time series input for a single, user defined, region of interest allows the algorithm to successfully accommodate subject and kidney specific variations at a low time cost. Manual correction of segmentations is very fast and represents a large time saving in the MR urography patient workup. Conclusion: A neural network segmentation algorithm using only MR urography time series presents a large time saving for renal segmentation in the area of clinical MR urography. Not only is entire renal volume attained, but three-dimensional compartment classification, necessary for functional analysis, is also provided.

Manon Pouvreau 1 , Jean Delmas 1 , Jean-François Chateil 1 

Purpose: To compare the detection of limb fractures in a pediatric population (0-18 years old) between an artificial intelligence (AI) software and a gold standard defined as pediatric radiologist report. This software has already proven its effectiveness in adult trauma but was not evaluated in children. Materials and methods: Single-center retrospective study, conducted on 838 children (393 girls, 445 boys, aged 6 months to 16 years; mean age 8.8 years) referred by the pediatric emergency room for an appendicular skeleton trauma. 27% of patients finally suffered of fractures, 61% of the images analyzed were normal, persistence of a diagnostic doubt following the first imaging procedure was present in 12% of cases. For each set of images in all patients, we analyzed the accuracy of the software (Smarturgences ® , Milvue company, Paris) to detect the presence/ absence of fractures, in comparison to the final diagnosis given by the pediatric radiologist (gold standard).After approval of ethic committee and parents, all the consecutive cases seen in the emergency unit from January to February 2020 were included. For this study, images from the PACS were sent to the software which returned back new images with 4 possible annotations: normal, fracture, doubt, intra-articular fluid within the elbow, with a rectangular mark around the lesion. The results of AI software were compared to the gold standard and statistical analysis was performed. Results: AI software detected fractures in 22% of patients. When compared to the gold standard, the answers were consistent in 74% of cases. In 11% of cases, it was not able to conclude on the presence or absence of a fracture ("doubt"). AI was also effective in the detection of elbow joint effusions, often the only element pointing to fractures in this area. The specificity of the software is 93% with a false negative rate of 4.6%. Some cases were more difficult for the AI, mainly extremities in younger children. Conclusion: The artificial intelligence software was able to detect a majority of fractures, but accuracy was not as good as the pediatric radiologist final analysis. There was a low rate of false-negative cases for AI. This tool appears useful as a diagnostic aid for the detection of fractures in the pediatric population; it may be helpful within the emergency room for general physicians when report of radiologist is not available in real time. Pointing abnormalities may also help to perform additional oblique views. Purpose: To investigate the best level to measure aortic flow for quantification of aortic regurgitation on 4D flow MR. Methods: In 29 congenital heart disease patients with aortic valve insufficiency (69% male, age range 6 to 63 years, two blinded observers retrospectively measured blood flow volumes on a 3D cine phasecontrast acquisition with a cloud-based application. Antegrade, reverse and net aortic flows, and regurgitant fractions were compared between six levels with one-way ANOVA: (1) below the aortic valve; (2) at the aortic valve, (3) in the aortic sinus, (4) at the sinotubular junction, (5) at the pulmonary arteries and (6) below the brachiocephalic trunk. Inter-reader agreement was assessed with intraclass correlation coefficient (ICC) and Bland Altman analysis. Results After excluding 6 patients with aliasing in the ascending aorta from the analysis, antegrade flow was not significantly different between measurement levels. In the ascending aorta (levels 3 to 6), reverse flow was higher than at or below the aortic valve resulting in higher regurgitant fractions. The lowest reverse flow and regurgitant fractions were measured at the aortic valve due to signal loss in the regurgitant jet. Inter-reader agreement of regurgitant fractions was better in the ascending aorta (levels 4 to 6: bias < 1%) than below the sinotubular junction (levels 1 to 3: bias 1.8% to 4.3%). The best absolute agreement (ICC 0.98, 95% confidence interval 0.94 to 0.99) and narrowest limits of agreement (agreement range 11%) were obtained at the level of the proximal pulmonary arteries. Conclusion On 4D flow MR, blood flow is best measured in the ascending aorta at the level of the pulmonary arteries for estimating the severity of aortic valve regurgitation. At this level reverse flow to the coronaries needs to be taken into consideration for assessing the true aortic valve regurgitation fraction. Methods/Background: Marfan syndrome is a connective tissue disorder that may affect various systems, including the cardiovascular, musculoskeletal, pulmonary, ocular, and integumentary. The diagnosis of Marfan syndrome is based on a combination of major and minor clinical features described in the Ghent classification system. Cardiovascular manifestations include annuloaortic ectasia, aortic aneurysm, aortic dissection, mitral valve prolapse and pulmonary artery dilatation. They are common causes of morbimortality in those affected by Marfan syndrome and, thus, the primary causes of reduction in life expectancy. Results/Findings: The following topics will be discussed and illustrated with teaching cases from our Radiology Department: -Marfan syndrome: Ghent criteria and the role of radiologists -Multisystemic findings (musculoskeletal, ocular, thoracic manifestations) -Cardiovascular features: a step-by-step approach 1. Anatomy of the aorta 2. Imaging the Aorta: Computed Tomography (CT) Protocol and Technique 3. How to measure and report the aortic segments in Marfan Syndrome 4. Recognizing the altered aorta and main pitfalls 5. Aortic findings in Marfan Syndrome: imaging and physiopathology 6. Aortic surveillance with angiographic CT Conclusion: Early identification and treatment of cardiovascular conditions allow an improved quality of life and a life expectancy close to the average for the general population. Radiologists are important in the diagnosis and follow-up of Marfan syndrome. Awareness of the radiologic appearances of the various Marfan syndrome manifestations warrants a prompt diagnostic and adequate management, with better outcomes.

Purpose: This poster attempts to portray the spectrum of anatomic variations seen in anomalous pulmonary venous return on MDCT. It attempts to simplify the approach to diagnose these anomalies and its associated cardiac imaging findings. Materials and methods: This is an educational poster depicting the key imaging appearances in the spectrum of anomalous pulmonary venous return. Results: Partial anomalous pulmonary venous drainage (PAPVD) describes the connection of at least one pulmonary vein to the systemic venous system or right atrium (RA). It has been reported to be between 0.4-0.7% 1 . It is more common on the right and results in the formation of a left-to-right shunt. If a significant left to right shunt is left unrepaired, pulmonary vascular remodelling can occur resulting in the development of pulmonary arterial hypertension (PAH). Eventually, the patient can develop shunt reversal and Eisenmenger's syndrome if the PAPVD is associated with an atrial septal defect (ASD) 2 . Total anomalous pulmonary venous drainage (TAPVD) refers to drainage of all four of the pulmonary veins to another cardiovascular structure other than the left atrium 3 and accounts for about 2% of cardiac malformations. Four types exist, depending on the level of drainage: Type 1 -supracardiac: This accounts for up to 55% of cases and is the most common. It typically involves convergence of all four pulmonary veins behind the heart to form a common vein. This then drains into the left brachiocephalic vein and henceforth into the SVC. Type 2 -abnormal communication at the cardiac level: drainage occurs into the RA or coronary sinus. Type 3 -drainage below the level of the heart or diaphragm, for example into the IVC, portal or hepatic veins. Type 4 -drainage at more than one levels. In patients with TAPVD, a right-to-left shunt is crucial for early survival, and this manifests usually in the form of a patent foramen ovale, an atrial or a ventricular septal defect. Patients present early in the neonatal period with symptoms of congestive cardiac failure and cyanosis. Conclusion: It is important to have the knowledge of the spectrum of anatomic variations seen in anomalous pulmonary venous return on MDCT. The clinical presentation of APVD is variable: TAPVD presents at birth, and is an emergency, whereas PAPVD could present even at adulthood with non-specific symptoms or atrial fibrillation, incidentally, being diagnosed on CT. A simplified approach to diagnose these anomalies and its associated cardiac anomalies is valuable.

Cardiac magnetic resonance imaging (MRI) is the reference standard imaging modality to evaluate cardiac masses in children. It does not use radiation and provides excellent soft tissue contrast. It is usually performed following echocardiography which although rapid, relatively inexpensive and non-invasive, has relatively poorer soft tissue contrast and limited ability to assess extra-cardiac structures. MRI may determine extent of myocardial, pericardial and coronary involvement as well as identify potential extra-cardiac involvement with an unrestricted field of view. By exploiting differences in hydrogen protein density and their relaxation properties, T1-, T2-weighted and contrast enhanced sequences can facilitate differentiation of thrombus from tumour and benign from malignant masses. MRI can also aid surgical planning with anatomical and functional information. The most common paediatric cardiac tumours are benign. Rhabdomyoma may be multiple, contiguous or infiltrative to the myocardium; typically, T1 iso-and T2 hyperintense to adjacent myocardium. Fibroma is usually solitary and T2 hypointense with delayed enhancement. A teratoma may be a multiloculated and cystic mass containing T1 hyperintense fat. Sarcoma; an infiltrative tumour extending across tissue planes and through vessels, with mixed T1/T2 intensity and enhancement, is the most common malignant paediatric cardiac mass. Cardiac metastases most commonly arise in the atrium and usually enhance with contrast. They may arise individually, by direct extension or haematogenous spread (e.g. from sarcoma, lymphoma, testicular carcinoma or Wilms). Not all cardiac masses are tumours. Thrombus, while rare in the paediatric population, is associated with myocardial infarction in patients with homozygous familial hyperlipemia or Kawasaki disease. Pericardial cysts do not enhance and are T2 hyperintense with variable T1 intensity depending on protein content. The rare congenital cardiac aneurysm or diverticulum manifesting on chest radiography as a mass, can be characterized with MRI by demonstrating a focal outpouching that communicates with a cardiac chamber. A diverticulum has a narrower inlet than an aneurysm and contracts in harmony with the cardiac chamber, while an aneurysm may be akinetic or dyskinetic. Having diagnosed a treatable cardiac tumour. MRI is also useful post-operatively or post-chemotherapy to assess for residual disease or recurrence. Case Report: Scimitar syndrome is a rare vascular anomaly whereby a partial anomalous pulmonary venous drainage to the inferior vena cava results in left-to-right shunt. Scimitar syndrome occurs as the result of abnormal development of the right lung bud in the early embryogenesis. The incidence of Scimitar syndrome ranges from 1 to 3 per 100,000 live births and a 2:1 female predominance. The term Scimitar syndrome was coined by Neill et al., with reference to the characteristic appearance of the anomalous right pulmonary venous confluence on the X-ray chest that resemble a curved Turkish sword called a Scimitar. Scimitar syndrome is associated with a number of cardiac and extra cardiac anomalies. Cardiac anomalies include dextrocardia, atrial septal defects, right pulmonary artery hypoplasia etc. . Extra-cardiac abnormalities include pulmonary hypoplasia, pulmonary sequestration, horseshoe lung, bronchiectasis, diaphragmatic hernia, vertebral segmentation anomalies etc. These multifarious features may often have unusual variations, which are sparsely encountered and enticed in the literature. We present a similar paradigm. Our indexed case is a 6yr old male Qatari patient, came for follow up management in our institution. The patient was diagnosed as a case of Scimitar syndrome at the age of 3months based on clinical and radiological investigations and underwent surgical correction in the form of VSD and PFO closure in addition to coil embolization of anomalous pulmonary venous channel draining to IVC. MDCT angiogram was done for the follow up evaluation, which revealed left bronchial isomerism with trilobated left lung, polysplenia and fused ribs; in addition to hypo genetic right lung, hypo plastic right pulmonary vein, right Morgagni hernia with focal hepatic herniation and hemi vertebra at T10-11. Conclusion: Scimitar syndrome usually manifests with multifarious cardiac and extra cardiac anomalies. In our indexed case, there had been unusual imaging features like polysplenia, left bronchial isomerism with trilobated left lung and fused ribs, in addition to more common extra cardiac features as described above. To our knowledge, these unusual features are sparsely reported in the literature, as constituents in the constellation of extra cardiac features of Scimitar syndrome; which are enticed in this paradigm. Congenital diaphragmatic hernia (CDH) is a diaphragmatic defect related to foetal development. In the UK it affects~200-300 births a year 1,2 . As a prevalent diagnosis, early recognition, appropriate investigation, and operative management is key to avoid poor patient outcomes. Furthermore, recognition of long-term complications is warranted to aid appropriate development. We have reviewed and analyzed 79 patient cases that have presented over the last 10 years with congenital diaphragmatic hernia at Chelsea and Westminster Hospital, a London Paediatric Tertiary Centre. Our educational presentation highlights common indications for imaging, presentation, multi-modality investigation techniques, immediate and long term post-operative complications. A pictorial review will be incorporated. We hope this educational case series will facilitate a wider recognition and understanding of congenital diaphragmatic hernia nationally and internationally. Purposes -To overview congenital lung malformations, according to their onset during the process of fetal lung development.

-To illustrate characteristic imaging appearances of common congenital lung malformations in various imaging modalities, approaching their differential diagnosis.

-To discuss the clinical significance and prognosis of the presented entities. Material and Methods: We performed a pictorial review of congenital lung malformations in the paediatric population studied in both our institutions, regarding the antenatal e postnatal periods. Results: We review the most important features of embryological lung development, as we consider them essential to understand the radiological appearances and clinical prognosis of congenital lung anomalies. In this work, we depict several cases of congenital lung malformations, such as abnormal lung with normal vasculature (congenital pulmonary airway malformation, congenital lobar hyperinflation, bronchial atresia, bronchial cyst?), abnormal vasculature and normal lung (arteriovenous malformation) and lesions with both parenchyma and vascular abnormalities (pulmonary sequestration, scimitar syndrome). We used a multimodality imaging approach, including plain radiography, ultrasound, computed tomography and magnetic resonance. This approach improves the detection and characterization of congenital lung malformations during both antenatal and postnatal periods. We discuss the most relevant imaging features of the depicted congenital lung malformations, as well as their main differential diagnoses. Conclusions: Imaging plays a central role in the detection of congenital lung malformations, as their clinical presentation is widely variable, ranging from an incidental finding on chest x-ray to severe respiratory distress at birth. Technical imaging advances in recent years, especially in computer tomography and magnetic resonance, have improved the detection and characterization of congenital lung malformations. This influence both the therapeutical approach and clinical prognosis of these patients. The choice of imaging modality must be individualized for the circumstances, preferences and abilities of those involved on imaging and in patient's care.

Purpose: Extralobar sequestration has its own pleural investment and is separated from the adjacent lung. It is attached to the mediastinum by its vascular pedicle. Torsion of an extralobar pulmonary sequestration is an unusual presentation, rarely recognized promptly, with the correct diagnosis often delayed. The purpose of this poster is to highlight the unique presentation and imaging features of this entity to aid in understanding and prompt identification. Material & Methods: 3 cases of torsed extralobar pulmonary sequestrations will be shown, all initially misdiagnosed. The characteristic location, plain film, ultrasound, CT and MR appearances will be illustrated. Results: All 3 children were male, two 6yrs and one 12years of age. Sudden onset of chest, back or abdominal pain was the typical clinical presentation. In two cases the initial workup was for intraabdominal pathology. Chest radiographs had a small cardiophrenic angle paraspinal density plus small pleural effusion, two on the left, one on the right, not recognized initially in two cases. US, CT and MR showed a small deep cardiophrenic oval to triangular, echogenic, low density/signal, poorly vascular, peripheral or nonenhancing intrapulmonary mass with surrounding pleural fluid with slightly higher attenuation than simple fluid on CT, T1 and T2 bright on MR consistent with proteinaceous fluid/ blood. The aberrant systemic artery was either not seen (thrombosed) or faintly visible. Despite these findings, initial suggested diagnoses were pulmonary/mediastinal neoplasm, pneumonia, or abscess. In all 3 cases an experienced pediatric radiologist suggested the correct diagnosis with surgical and pathologic confirmation of torsed necrotic extralobar sequestrations. Conclusion: An astute radiologist is often the first person to recognize the characteristic imaging features of a torsed extralobar sequestration. It is important to differentiate this entity from infection or other lesions to direct treatment toward surgical resection. The combination of sudden onset of pain, typical location and appearance on imaging should trigger suspicion for this entity, despite the absence of a visible systemic artery. Purpose: A Classic Metaphyseal Lesion (CML) or metaphyseal fracture is a subtle fracture that is considered highly specific for child abuse. The initial imaging method in imaging suspected child abuse in clinical practice is x-ray radiography. However, it is sometimes a challenge to diagnose this fracture by x-ray radiography alone. Currently, there is no systematic review comparing the diagnostic accuracy of medical imaging modalities for diagnosing these fractures.

To assess the diagnostic accuracy of medical imaging modalities in diagnosing CML in infants and young children with suspected inflicted trauma. To explore the advantages and disadvantages of medical imaging modalities in suspected child physical abuse. Methods: This systematic review was conducted according to the PRISMA checklist and QUADAS-2 tool criteria. Predefined keywords were used to search online databases for English articles published between 1st of January 1980 and 1st of April 2021. Results: The initial search revealed 61 studies, 6 of which met our inclusion criteria. Autopsy did not detect 24 CMLs that were visible on skeletal surveys (SS). The sensitivity and specificity of positron emission tomography (PET) were found to be 67% and 99%, respectively. In one study, sensitivity of ultrasound (US) for two readers was 55% and 63.2% while the specificity was 97.7% and 96.7%, respectively. One study used magnetic resonance imaging (MRI) whole body screening, which had a sensitivity of 31%. Two studies used bone scintigraphy (BS), with the detection rate in the first study being 35%, while in the second study, BS did not detect 5 CMLs that were visible on SS. Computed tomography (CT) was not used to detect CMLs in any diagnostic accuracy study. Conclusion: This systematic review identified only a small number of eligible studies. In addition to SS, PET and US may be helpful in the diagnosis of CMLs, particularly in resolving uncertainties. However, US has more potential than PET, due to its high specificity, lack of radiation exposure, low cost, and portability. Purpose: Child abuse is a significant worldwide problem with serious long-term consequences. The knowledge, awareness and professionalism of healthcare providers regarding child abuse are key for identifying and reporting suspected child abuse. Radiologists and radiographers play a vital role in the diagnosis of suspected physical child abuse. This study aims to assess the current practice, knowledge and awareness of radiologists and radiographers pertaining to child abuse in Saudi Arabia (SA). Material and Methods: A web-based questionnaire was distributed to radiographers and radiologists working in SA via national radiology societies and social media channels (i.e., established WhatsApp and Telegram groups of radiographers and radiologists working in SA) over a six week period (27 Oct -8 Dec 2021). Survey questions covered demographic and job information, knowledge regarding child abuse, professional practice in radiology departments in SA, and the reporting and acting procedure in cases of suspected physical abuse (SPA). Results: A total of 315 respondents (91 radiologists and 224 radiographers) participated in this study. The median score for knowledge of abuse was higher amongst radiologists (4.80) than radiographers (4.00) with P-value <0.001. In total, 210 (93.8%) radiographers and 61 (67%) radiologists reported there was no protocol (i.e., skeletal survey) in their hospital for imaging children with SPA. Most radiographers (191/224, 85.3%) and more than half of responding radiologists (55/91, 60.4%) had no awareness of international guidelines for imaging children with SPA. Most radiographers (165/224, 73.7%) had no training in paediatric radiology and most radiologists (73/91, 80.2%) had received no training in evaluating injury in children related to SPA. Over half, 131 (58.5%) radiographers and 44 (48.4%) radiologists were not familiar with the reporting and acting procedures in their hospitals in cases of SPA. Conclusions: Although the radiologists and radiographers in SA have good knowledge and awareness of child abuse in general, they lack specific knowledge of the reporting and acting procedures in their hospitals in cases of SPA. National imaging guidelines and appropriate training courses are needed to develop skills in the recognition and the imaging and radiological reporting of SPA in infants and young children in SA. . Occasionally a radiologist may encounter a normal or developmental variant in the metaphysis that raises concern of a fracture (Kleinman et al 1991) . It is essential to understand subtle features that can differentiate a normal sub-periosteal bone collar (SPBC) from a classic metaphyseal lesion (CML), a high specificity indicator of infant abuse. The purpose of this educational exhibit is to review the radiographic feature of normal metaphyseal variants that arise from the SPBC and discuss features that allow them to be distinguished from the CML. Materials and Methods: Multiple examples of CML mimics pulled from a review of high detail skeletal surveys will be illustrated, including stepoff, spurs, beaking, pseudo-cupping and other oddities. Differentiating features elucidated by correlating histology and CT will also be presented. The value of follow-up imaging will be emphasized. Purpose: Ionizing Radiation is used in medical diagnosis and treatment pathways. Dose reference levels (DRL) are important to monitor and audit patient dose. They are used to report significant accidental and unintended exposures, and are required under UK law (1) . The purpose of this study is to develop effective local DRLs for use within a paediatric Interventional Radiology department where procedures are replicable and of standard technique. Materials and Methods: A retrospective audit of procedures undertaken in three biplane IR suites of a tertiary referral paediatric hospital over a 33month period from January 2019 -September 2021 was completed. Screening time, dose area product, skin dose, interventional method (single or biplane), grid used, image number and acquisitions were collated for 3,385 procedures. Data was categorized by examination subtype and patient weight for each procedural room. A minimum sample category of 10 patients per examination and per weight range was used to create the LDRL. Summary of the results: The results present comprehensive data for Dose Reference Levels for procedures undertaken on Paediatrics in Interventional Radiology. To enable local Dose Refence levels to be set to comply with national IRMER 2017 regulations. A table was compiled displaying the DRLs and grouped into categories. This data has been compared to Adult National DRLS in which the DRL for and adult having a tunneled CVC, 3Gycm² is 20 times more than our local paediatric dose reference level 0.15Gycm². Conclusion: The data obtained in this study establishes local DRLs. The comparison to national Adult DRLs shows that there is a need for Paediatric DRLs to be set. These will facilitate dose monitoring, technique development, and trigger investigation of high doses. This is the start of a collaboration to get national paediatric dose reference levels relevant to practice. Purpose: Following a miscarriage, many parents want to know why their baby died, however some find conventional post-mortem investigations too invasive and therefore decline (1). Minimally-or non-invasive postmortem approaches are shown to be more acceptable to parents following a pregnancy loss (1) . Micro-CT is now being used as a novel post-mortem imaging technique following early fetal death to identify structural abnormalities through high-resolution imaging (2). Providing parents with a cause of death can reduce feelings of guilt, influence future pregnancy decisions and help parents move on (3). Our aim was to identify parental perceptions of this micro-CT technique. Materials and Methods: Recruitment for two focus groups of parents who had experienced a miscarriage was conducted via direct email and The Miscarriage Association Facebook group. A short presentation on micro-CT technique was delivered to both focus groups along with its advantages and limitations and images of anonymized human fetal micro-CT scans were demonstrated. Questions explored parental attitudes towards the acceptability of the micro-CT procedure, its benefits, and parental concerns. The audio-recordings were transcribed and analyzed using thematic analysis. Results: The overriding message from participants was the positive impact micro-CT could have as a diagnostic post-mortem imaging technique, with its ability to provide detailed medical images through a non-invasive approach being a major advantage. Themes were clustered into those that related to the inner, emotional world, and those that related to the outer, practical world. Benefits around increased investigational choice, hope for the future and the potential to provide answers as to why the miscarriage had occurred were all deemed important by the participants. All the participants agreed that they would have consented to a post-mortem micro-CT if available at the time of their pregnancy loss. Conclusions: Parental perception of micro-CT was overwhelmingly positive, with particular benefits of diagnostic potential and patient choice. Further research into the experiences of those offered this novel imaging technique at post-mortem is warranted. Case presentation: A 23-year-old female (gravida 3) was referred for a fetal body MRI study for ultrasonographic features concerning esophageal atresia and bowel atresia. The MRI at our institute was performed at 27 weeks of estimated gestational age. The MRI did not show the proximal esophageal pouch, although there were indirect signs of esophageal atresia (more fluid in the pharynx, a small stomach, very little meconium, small overall volume of the abdomen, and polyhydramnios). Additionally, a big oblong cystic lesion was found in the right upper abdomen, that was T2 hypointense and T1 hyperintense. We performed a repeat fetal MRI with cine sequences which showed the esophageal pouch, confirming the diagnosis of esophageal atresia. The cystic lesion in the right upper abdomen had the same appearance, but grew in size. The pregnancy was continued and at 38 weeks of gestation the girl was born. Immediately after birth esophageal atresia with tracheoesophageal fistula was confirmed by radiography. The bowel loops at first didn't seem abnormal, so on the first day only esophageal atresia was surgically corrected. After the surgery a very wide air-filled sac (bowel segment) started appearing in the right upper abdomen on radiography. Contrast enema study showed a normal large bowel and a persistent dilated airfilled sac in the right upper abdomen that didn't fill with contrast. The baby had another surgery the following day. A large Meckel diverticulum filled with meconium was found at surgery; the rest of the bowel was normal. The post-surgical recovery was uneventful. Discussion: We presented a rare case of prenatal diagnosis of Meckel diverticulum. Differential diagnosis of a fetal cystic abdominal mass is wide and includes ovarian cyst, duplication cysts, meconium pseudocyst, segmental ileal dilatation, bowel atresia, anorectal malformation (ARM), and Meckel diverticulum. A definite diagnosis is hard to obtain with ultrasound. MRI can help differentiate fetal gastrointestinal tract abnormalities, especially with the typical hyperintense T1 and hypointense T2 signal of meconium, its distribution within the bowel, and better visualization of the anorectal segment. In our case, the large abdominal cyst showed the typical meconium signal and the anorectal segment appeared normal, which excluded ovarian cyst, bowel atresia or ARM. After the birth, the cyst filled with air, which also made the diagnosis of duplication cyst or meconium pseudocyst less likely. The surgery and pathology reports set the final diagnosis of Meckel diverticulum. Hartsfield syndrome is the most severe expression of the spectrum. The first case in our series is a foetal MRI at 31 weeks gestation. The following findings were observed: partial agenesis of the corpus callosum, vermis and cerebellum in the p10, holoprosencephaly, olfactory bulbs agenesis and a cleft lip and palate compatible with Hartsfield syndrome. Postmortem MRI allowed for a better characterization of the Hartsfield syndrome because it allowed a better depiction of the body and vertebral findings We performed a MRI of the father with the following findings: hypoplasia of the olfactory bulbs, small hypophysis and a small vermis, compatible with Kallman syndrome. The patient underwent a third pregnancy in which we performed a foetal MRI at 29 weeks gestation with the following findings: agenesis of the olfactory bulbs, dysgenesis of the corpus callosum, hypoplastic vermis and cerebellar hemispheres consistent with Kallman syndrome with additional features (Kallaman plus).

Conclusions: Our series of cases of the same family demonstrates a spectrum of anomalies related to the loss of function of the FGFR1 gene. This spectrum includes asymptomatic cases, hypogonadotropic hypogonadism, isolated Kallman syndrome, Kallman syndrome with additional features and Hartsfield syndrome. It also illustrates the added value of performing postmortem MRI to a better depiction of the body findings as well as an aid to the conventional autopsy. (1), mesoblastic nephroma (1), neuroblastoma (1), mesenchymal hamartoma of the chest wall (1) and mesenchymal hamartoma of the liver (1). Some tumors could not be classified due to lack of feedback or no histopathological diagnosis. Conclusion: MRI is a well-established second-line imaging method for diagnosing fetal tumors. It is used to verify the prenatal US findings and thus impacts patients' clinical management. Some of the tumors have distinct imaging characteristics which we depicted in this poster.

Terry Humphrey 1 , Helen Woodley 1 , Jeannette Kraft 1 , William Ramsden 1 1. Leeds Children's Hospital, Leeds, United Kingdom Background: Necrotising enterocolitis (NEC) predominantly affects infants with very low birth weight as their immature intestine is vulnerable to microbial pathogens. Advances in neonatal care have improved survival rates leading to a relative increase in the incidence of NEC¹. Whilst abdominal radiography (AR) is the main imaging tool in the diagnosis of NEC, ultrasound (US) has the ability to detect disease earlier.

Purpose: To review the imaging of infants with suspected NEC in our institution and ascertain if US is being fully utilized to detect early signs of NEC often not visible on AR, as early diagnosis may lead to improved outcomes.² This study includes a pictorial review demonstrating the advantages of US in the assessment of NEC. Methods: The incidence of infants with suspected NEC and the associated imaging were accessed from the neonatal and radiology databases. US appearances associated with both early and severe disease were reviewed and compared to AR findings to see if sonography is more sensitive for early disease and/or detecting complications. Results: From January 2019 to December 2021, 110 infants (66 male) presented with suspected NEC. The average gestational age was 29.6 weeks (range 23-40 weeks) and mean birthweight 1409g (range 435-4250g). All underwent AR whilst US specifically to assess the bowel for NEC was performed in 48/110 cases (43.6%). Conclusions: AR remains the main diagnostic tool in the assessment of NEC. However in skilful hands US can detect early signs of NEC. One of the main barriers of using US in the assessment of NEC is the examinations are technically challenging and there is a lack of experience. If an abdominal radiograph has demonstrated pneumatosis treatment is commenced and US is often not required unless there is a suspected complication. However, US has the ability to detect subtle intramural gas in early disease before it becomes evident on a radiograph and so enable earlier treatment. In more advanced disease portal venous gas, pneumoperitoneum and complex abdominal collections can be assessed without a radiation penalty. Increasing the use of US in both early and established disease will improve technical skill, early diagnostic capabilities and patient outcome. We report three cases of autoimmune pancreatitis, two of them presenting as an inflammatory pancreatic mass and the other one as a diffuse sausage-like enlargement of the gland with elevated serum IgG4 associated; two cases of drug-associated necrotizing pancreatitis; and one case of acute pancreatitis in a child with pancreas divisum, an anatomical pancreatobiliary abnormality. All subjects in this work had no pancreatitis-predisposing genetic mutations identified, excluding genetic risks factors. Results: In the last decades, acute pancreatitis (AP) has been increasingly diagnosed in children [1] . The etiology of AP in children is often drugs, trauma, infections, obstructive (including biliary), anatomic abnormalities, associated with systemic diseases, or idiopathic [2]. Diagnosis is based on clinical symptoms, elevated serum pancreatic enzyme levels, and imaging studies. The main symptoms include epigastric abdominal pain, irritability, vomiting, and fever, but the presentation can be atypical, which emphasizes the role of imaging [3]. Children with AP, in general, have a mild course. However, a subset of patients may develop recurrent episodes of acute pancreatitis (acute recurrent pancreatitis, ARP), and some progress to chronic pancreatitis (CP) [1] . Autoimmune pancreatitis, a form of CP, can present as mass-forming pancreatitis and mimic a tumor. The performance of a percutaneous biopsy in these cases should be considered, avoiding unnecessarily pancreatic resection [4] . Ultrasound (US), computer tomography (CT), and magnetic resonance imaging (MRI) are the three main noninvasive imaging modalities for evaluating pancreatitis in children. US should be the initial study of choice in children with suspected AP, particularly because it allows the diagnosis of obstructive causes, such as choledocholithiasis, and characterization of acute fluid collections, pseudocysts, and walled-off necrosis. CT should be reserved for the assessment of potential complications and for detection of pancreatitis causes that cannot be elucidated with US. MRI is useful to visualize biliary and pancreatic tracts, allowing identification of structural or obstructive causes and is helpful in the characterization of mass-forming pancreatitis [4, 5] . Conclusion: Pediatric pancreatitis is an entity with unique characteristics. Symptoms can be atypical at presentation, with etiology and clinical course distinctive from the adult form, and so imaging has a powerful role in the evaluation of this entity. Material and Methods: The following work shows the imaging findings of patients diagnosed with EO-IBD with alterations at magnetic resonance imaging (MRI) scans. Were included 7 patients from a total of 18 children diagnosed with EO-IBD in the last 12 years at our institution. Ileal involvement was seen in 4 patients, 2 of them with synchronous involvement of the colon, and perianal involvement was present in 3 cases. Isolated perianal disease at diagnosis occurred in one of the patients. Results: Inflammatory bowel disease (IBD) is an auto-immune condition characterized by chronic gastrointestinal inflammation. The incidence of pediatric IBD, particularly the early onset disease subtypes, has been increasing worldwide, indeed approximately 25% of IBD patients contract the disease within their pediatric years (1, 2). EO-IBD is defined as disease presenting before the age of 10, according to the Montreal classification (3). EO-IBD represents a challenge both in terms of treatment and diagnosis, with a different clinical presentation and a more severe course when compared to IBD presenting in the adolescent or adult. There is increasing data supporting that IBD is influenced by genetics, indeed nowadays is possible to identify specific genetic mutations associated with some patterns of EO-IBD, unfortunately, more likely to be resistant to conventional medical treatment (4). EO-IBD may be subtyped into Crohn's disease (CD), ulcerative colitis (UC), or the additional category of inflammatory bowel disease -unclassified (IBD-U), also known as indeterminate colitis (4) . Clinical presentation is broad and non-specific, and frequently EO-IBD is unclassifiable into CD and UC. The most frequent initial gastrointestinal manifestations are isolated colitis and rectal bleeding (5) . The diagnosis of IBD is based on endoscopy with histology of both the lower and upper gastrointestinal tract, imaging of the bowel, and biochemical investigations. Cross-sectional imaging is complementary to endoscopic assessment, particularly in the evaluation of small bowel and perineum, assessing mural and extramural disease, such as abscess, bowel perforation, and enteric fistula. Additionally, MRI and CT allow the detection of extraintestinal IBD manifestations. The choice of imaging will depend on the need to determine distribution and extent or assess activity of the disease, and to identify extramural complications. Conclusion: EO-IBD is a diagnosis with several characteristics that are distinctive from the adolescence or adult form. It is critical for pediatric radiologists to be aware of the etiologic, clinical, and prognostic characteristics that are unique to this age group in order to optimize their care particularly because imaging continues to play a key role in this entity.

Gozde Ozer 1 , Nursun Ozcan 1 , Berna Oguz 1 , Mithat Haliloglu 1 1. Hacettepe University Faculty of Medicine, Ankara, Turkey Neonatal colon pathologies require prompt and accurate diagnosis to avoid potential morbidity and mortality. Symptoms such as abdominal distention and failure to pass meconium may require radiological evaluation. Abdominal radiography should always be the first step in radiological examination. In addition, fluoroscopy is widely used to define anatomy and pathologic intestinal segment. In this presentation, we aimed to review the radiological findings of common and rare neonatal colon pathologies with case examples. Developmental Anomalies Hirschsprung disease: Hirschsprung disease is characterized by the absence of ganglion cells in the affected colon segment, mostly in the rectum and sigmoid. Total colonic aganglionosis: Total colonic aganglionosis is a subgroup of Hirschsprung's disease in which the entire colon is aganglionic. Segmental dilatation of the colon: Congenital segmental dilatation of colon is a very rare neonatal condition characterized by the limited dilated segment with abrupt transition between normal and dilated segment. Colonic atresia: Congenital colonic atresia is a rare cause of intestinal obstruction in newborns. Anorectal malformations: Anorectal malformations encompass the spectrum of anal atresia and stenosis. Approximately 95% of patients have a fistula to urethra or vagina.

Meconium ileus: Meconium ileus refers to neonatal distal ileal obstruction due to thick and impacted meconium. It is usually a manifestation of cystic fibrosis. Ileal atresia: Ileal atresia is likely due to intrauterine vascular insult resulting in necrosis and resorption and leading to segmental stenosis. Functional immaturity of the colon: Functional immaturity of colon is also known as meconium plug syndrome and small left colon syndrome. Acquired Pathologies Necrotizing enterocolitis: Necrotizing enterocolitis is the most common gastrointestinal emergency in newborns. It is characterized by mucosal injury, ischemia and necrosis. Post-necrotizing enterocolitis strictures. Radiology plays a fundamental role in the diagnosis of neonatal colon pathologies. Familiarity with the radiographic and fluoroscopic patterns of neonatal colon diseases is important for prompt diagnosis. Although some entities can be diagnosed with prenatal ultrasound or MRI, postnatal radiographs and fluoroscopy remain the essential imaging modalities for colon pathologies. Purpose: To describe our experience in MR enterography (MRE) in children giving oral contrast before and during general anesthesia (GA). Material and methods: This is a retrospective descriptive cross-sectional study. Patients under 18 years of age with MRE requiring general anesthesia, performed between 2018 and 2021 in our institution, were included. Preparation: To achieve an optimal intestinal distension reducing the anesthesia time, the following sequence was performed: 4 hours solid fasting, ingestion of an isotonic drink or sugar water, 2 hours complete fasting, general anesthesia with tracheal intubation, administration of 50% diluted mannitol through a nasogastric tube. After a 20-minute wait for contrast progression, MRE with intravenous contrast was performed. In each case, the reason for the study, the imaging findings, the degree of intestinal distension and the contribution of the MRE were recorded. Results: We performed 25 studies in total, 13 girls (52%) and 12 boys (48%). The mean age was 5.8 years (±4.7 years). The most frequent indication was "suspected inflammatory bowel disease (IBD)", 11 patients (44%), "IBD controls", 5 cases (20%) and "gastrointestinal bleeding", 3 cases (12%). Adequate intestinal distention was obtained in 15 patients (60%) and moderate distention in 7 patients (28%). Mean exam length duration (MRE) was 42 ± 20,1 minutes for patients undergoing GA. Median time under GA was 73 ± 20,9 minutes. As MRE findings, predictors of IBD were found in 12 patients (48%), 7 studies without pathological findings (28%), 2 studies with polyps (8%) and one patient with intestinal malrotation (4%). Conclusions: MR enterography is an increasingly important pediatric imaging modality that is most often used to diagnose and follow-up IBD. We obtained good or very good small bowel distention in most cases, with the described institutional technique. The goal of our twostage technique is to substantially reduce anesthesia times. Purpose: To describe and illustrate esophagram and, specially, pneumo-CT (Pn-CT) imaging findings in pediatric patients with various esophageal diseases. Material and methods: Pn-CT scans of patients under 18 years old performed at the institution from January 2009 to February 2022 were reviewed. The procedures were performed under sedation, with a 4-hour fasting period. Optimal esophageal distention was obtained using a Foley catheter placed up to the upper third of the esophagus, through which carbon dioxide was insufflated continuously at a regulated pressure. The cases that showed characteristic findings of different esophageal abnormalities and were studied with both Pn-CT and esophagram were selected for their description and demonstration. Results: Seventeen cases of pediatric patients with suspected or diagnosed esophageal disease who underwent Pn-CT at our institution were reviewed. Esophagrams and Pn-CT of one normal examination and selected patients with diagnosis of type III esophageal atresia with esophageal-pulmonary fistula, type III esophageal atresia with residual esophageal stricture, esophagitis from impacted foreign body, congenital esophageal stenosis and a vascular ring are shown. Pneumo-CT provided anatomical detail for better therapeutic planning in cases of esophageal atresia type III and congenital esophageal stenosis with residual stenosis, determining its location and extension. In 2 cases it allowed the diagnosis of esophageal-pulmonary fistula and bronchoesophageal fistula that were not seen in previous esophagrams. In a patient with type III esophageal atresia with poor clinical course, the possibility of fistula and residual stenosis was ruled out since Pn-CT was normal, and in a case of esophagitis from impacted foreign body, the presence of circumferential mural thickening, alteration of the surrounding fat and mediastinal reactive lymph nodes oriented the diagnosis towards benign pathology of inflammatory origin. Conclusions: Pneumo-CT is an excellent complement to the esophagram since it provides information not only on the esophageal lumen but also on transmural and extraesophageal involvement, which is extremely useful in selected cases of patients with complex esophageal pathology, aiding in diagnosis and therapeutic planning. To this end, creation of a successful Pn-CT protocol requires a multidisciplinary approach involving communication and education among all staff involved. Purpose: To familiarize with the radiological Whirlpool Sign (WS) in paediatric conditions and its potential pitfalls when interpreting this sign. Practical tips will also be shared on how to troubleshoot various different imaging modalities in order to appreciate and visualize the WS better. Material and Methods: The WS is seen when a structure twists upon itself with the twisting vessels resembling a body of rotating water. The sign may be exhibited on Ultrasound, CT and MRI. Occasionally, the sign is not well appreciated in the standard axial, sagittal or coronal sections and reconstructions in different planes may be necessary to demonstrate the sign. The presence of the WS is highly suspicious of reduced or absent blood flow towards a visceral structure and if left untreated, may lead to infarct, gangrene and life threatening sepsis. The WS is most often seen in cases of testicular or ovarian torsion, malrotation complicated by midgut volvulus and other types of bowel volvulus such as sigmoid volvulus and closed loop obstruction. However, it can present in any structure that has twisted around its pedicle. Results: Life cases where the radiological WS is demonstrated will be illustrated in this exhibit on still images and cine clips with accompanying pathological specimens and intra-operative images. Other imaging features pointing towards the diagnoses will also be highlighted. Potential pitfalls such as the normal counter-clockwise rotation of the superior mesenteric vein around the superior mesenteric artery being a normal finding and the absence of a demonstrable WS does not exclude of torsion will be shown and discussed as well. Conclusions: Recognizing the radiological WS and its significance in paediatric conditions is essential as it has implications on timely clinical management, particularly in the emergency acute setting. Purpose: To illustrate radiological characteristics of focal splenic lesion in pediatrics, using different imaging approaches. Material and methods: We report radiological characteristics of focal splenic lesions in children with emphasis on Ultrasound (US), contrastenhanced US (CEUS), Magnetic Resonance (MR) and Computed Tomography (CT) findings. A correlation between radiological and histological results is reported when available. Results: We describe the most frequent benign and malignant splenic lesions we can face in our clinical practice, correlating radiological characteristics with pathological features. A multiparametric approach combining US, CEUS, MR and CT findings is helpful in suggesting a specific diagnosis, the integration of all imaging data helped us to solve the diagnostic dilemma, especially in the most complex cases. Conclusion: Knowledge of the most frequent focal splenic lesions and their radiological features is crucial for a good management of these pediatric patients. Collaboration between radiologists, clinicians, surgeons, and pathologists can prevent unnecessary invasive treatments, avoiding life-long unpleasant consequences in children.

Shahab Shahipasand 1 , Patricia Set 1 , Jacqueline Hughes 1 , Anna Gomez 1 , Ben Fleming 1 1. Cambridge university Hospitals, Cambridge, United Kingdom Introduction: Intestinal malrotation, situs viscerum inversus, heterotaxy, organomegaly and ascites are among the contraindications for insertion of Percutangeous Endoscopic Gastrostomy (PEG). Fluoroscopic contrast studies have been increasingly requested by clinicians for infants and children prior to PEG insertion to exclude presence of malrotation. Our hypothesis from recent experience was that routine UGI studies were unnecessary unless indicated by patient's clinical signs and symptoms. Materials And Method: We reviewed 1024 upper gastrointestinal barium or water-soluble contrast studies of the paediatric population at Addenbrooke's Hospital, Cambridge from October 2016 to July 2021. 91 studies were identified as pre-PEG requests to assess for malrotation (age range 0 -15; 48 males, 43 females). Results: 71/91 (78%) of the cases were normal (8 had other incidental findings). 17/91 (18%) were reported as indeterminate, the majority of which were secondary to redundancy of the duodenum. 3/91 (%) were positive for malrotation of which one was confirmed to have gastric volvulus. The requesting clinicians had indicated suspicion of presence of malrotation in 6 of the studies in the request form. 4 of these studies were normal or indeterminate while 2 demonstrated presence of malrotation. Therefore, malrotation was confirmed in only one study in which there was no apparent previous clinical suspicion. Conclusion: With 97% of the cases being normal or indeterminate, we can conclude that performing contrast studies routinely are unlikely to be time saving or cost effective. Furthermore, they lead to many children and infants being exposed to unnecessary radiation. Therefore, a guide for the requesting physicians to discuss appropriate cases with the radiologists can be helpful to improve the sensitivity of such studies which can be evaluated by completing the audit cycle.

Duygu Cengiz 1 , Evrim Ozmen 1 , Mine Sorkun 1 , Pelin Oguzkurt 1 1. Koc University School of Medicine, Istanbul, Turkey Introduction: Tracheobronchial remnant is a very rare pathology with incidence of 1/50,000-100,000. We herein report a twenty-month-old girl presented with vomiting and who was diagnosed as achalasia in different center. Case description: Twenty-month-old girl presented to our hospital with vomiting after every meal and growth retardation. The symptoms started when the patient was 6-month-old, at the time of starting solid foods. Also, the child suffered recurrent pulmonary infections. In different hospital, she had esophagography and diagnosed as achalasia. Fluoroscopic examination of the esophagus and stomach was repeated in our hospital. The fluoroscopy showed that dilatation of the esophagus was increased, and the passage became narrower. There was segmental constriction in distal esophagus without typical appearance of achalasia that is gradual decrease of esophageal diameter with bird beak sign. Gastroscopy could not pass to stomach due to stenosis that is hard to dilate. In addition, balloon dilatation was not efficient to create feasible passage. As a solution, esophageal resection and anastomosis were performed. The pathology showed tracheobronchial remnants in esophagus wall. Five days after the operation upper gastrointestinal series showed passage with 27 mm diameter without any extravasation. Discussion: Congenital esophageal stenosis is a very rare reason of recurrent vomiting and dysphagia, which is typically start after solid food introduction. According to histological findings, congenital esophageal stenosis is divided in to three types: tracheobronchial remnants, membranous web and segmental fibromuscular hypertrophy of the muscle. Tracheobronchial remnants are caused by incomplete division of the primitive foregut and respiratory tract. Esophagogram shows a segmental constriction of distal esophagus and dilatation of proximal esophagus. Pendulum sign and mouse tail sign can be seen with tracheobronchial remnants on esophagogram. The differential diagnoses include gastroesophageal reflux disease, achalasia, esophagitis, and stenosis due to corrosive intake. Surgery including laparoscopic methods is the treatment choice. Purpose: -Describe technical aspects of pediatric MR urography in case of duplex collecting system and the role of each sequence -Provide a systematic analysis of MR urography in duplex collecting system to guide surgical care -Illustrate the presenting symptoms and the abnormalities associated with duplex collecting system. Material and methods: A review of the state-of-the-art MR urography technique will be presented. Cases of duplex collecting systems have been extracted from our data base, and most didactic and interesting cases will be presented. Results: -MR urography and cystography are indicated in case of complicated duplex collecting system (pyelonephritis, collecting system dilatation, suspicion of ureteral ectopia). The state-of-the-art protocol should be adapted according to the clinical context and the surgeon's questions.

-MR urography can differentiate complete (2 ureters, 2 ureteric insertions) from incomplete (2 ureters, 1 ureteric insertion) duplex collecting system. -MR urography identify the associated complications of complete duplex collecting system (ectopic ureteral insertion, upper pole moiety dysplasia, lower pole moiety ureteropelvic junction obstruction, ureterocele).

-MR urography allows a detailed and precise analysis of both the morphology and the relative renal function for each moiety. Conclusion: MR urography is indicated in complicated duplex collecting system. A systematic analysis is necessary to provide key information to guide surgical care (complete or incomplete duplication, ectopic ureteric insertions, ureterocele, relative renal function of each moiety). Purpose: Ultrasound elastography represents a non-invasive imaging technique of tissue stiffness by measuring distortion of the tissue in response to a slight pressure. Kidney is a unique organ and has a complex internal architecture with its intrinsic or extrinsic factors such as perfusion, urinary pressure, anisotropy and kidney position that may affect its viscoelasticity. Specific training and technique optimisation is necessary as well as acknowledging technical and pathological factors which may influence it. Our study aimed to discriminate renal allografts with impaired function by measuring Young modules (YM) in renal cortex using point Shear Wave Elastography (pSWE) and Virtual Touch Quantification (VTQ) in paediatric and young adult allograft recipients. Material and Methods: We prospectively included 23 kidney allograft patients (mean age 14±7yrs, 13 males) with clinically stable function in prior 6 months. Measurements were done after placing region of interest in renal cortex; six measurements in each region were performed with the subject lying in the supine position, if possible, during breath holding, with minimal pressure. YM was correlated to calculated glomerular filtration rate (GFR), resistive index (RI) and serum creatinine levels (sCr) and compared between patient groups with good (GFR?60 mL/min/ 1.73m2-group I) and impaired allograft function (GFR<60 mL/min/ 1.73m2-groupe II). Results: Overall YM showed mean value of 27.86±12.20kPa. Pearson correlation coefficient presented highly statistically significant negative correlation between calculated GFR and YM values in all patients (r= -0.64, p=0.0009), with moderate significant correlation with sCr (r=0.48, P=0.02) and no significant correlation with RI (r=0.252, p=0.258). Mean GFR value in group I was 73.13±8,67ml/min/1.73m 2 and in group II 46.76±9.04ml/min/1.73m 2 , with highly significant difference (p<0.0001), while mean YM value in group I was 19.61 ± 5.35 kPa and in group II was 34.21 ± 12.28 kPa with highly significant difference (p=0.002). No significant difference was found in mean RI values between groups (p=0.238). Conclusion: Elastography can be considered as a potential diagnostic biomarker in kidney diseases and renal allografts assessment. The inverse correlation of parenchymal stiffness with calculated GFR may reflect functional status of the renal allograft and differs between patients with good and impaired allograft function. Despite recent advances in imaging and management, urolithiasis remains an important cause of morbidity in the paediatric population. DMSA (dimercaptosuccinic acid) scans are widely regarded as important tools in the evaluation of function, structure and location of the kidneys, particularly in those children that present with recurrent UTIs. The combination of functional DMSA information with a low dose CT in the form of a SPECT CT provides useful information which is of particular use in pre-operative decision making. In our tertiary center hospital we have a cohort of patients with complex nephrolithiasis, and we have performed an increasing number of DMSA SPECT CT studies in a select subgroup of these patients. DMSA studies were acquired as both planar and SPECT images, followed by low dose CT of the urinary tract. The images were co-registered using the Hermes software. All DMSA SPECT CT studies from 2013-2021 were reviewed (total: 74 scans). The indications for the studies were reviewed, along with the outcome of the most recent ultrasound. We identified specific cases in which SPECT CT offered information over and above that provided by ultrasound alone. For example, a case of a duplex kidney with calculi only in a single moiety. Due to poor function of the involved moiety a decision was made to resect this rather than perform a calculus removal procedure. We have found this technique to aid with the assessment of complex calculi (e.g. staghorn calculi, multiple calculi in cystinuria) and in patients with complex anatomy (e.g. scoliosis, horseshoe kidneys). In this exhibit we will briefly review the physics and physiology behind the acquisition of a DMSA SPECT CT study. We will present a series of cases in which the SPECT CT has directly influenced the care of a patient, and highlight the imaging of these patients. Purpose: Perfusion represents a blood flow at the level of the tissue capillary bed and determines the delivery of nutrients and oxygen to the tissue. Renal perfusion is also a key determinant of glomerular filtration, therefore, a central measure of renal function monitoring. The development of a non-invasive and reliable method for renal perfusion estimation that would reflect glomerular filtration rate (GFR) would significantly improve on-time identification of potential allograft injury. Our study aimed to discriminate renal allografts with impaired function by measuring cortical renal blood flow (cRBF) using magnetic resonance imaging arterial spin labelling (ASL-MRI) in paediatric and young adult patients. Material and Methods: We included 20 kidney allograft patients and performed ASL-MRI on 1.5T MRI to calculate cRBF on parameter maps. cRBF was correlated to calculated glomerular filtration rate (GFR) and compared between patient groups with good (GFR>60 mL/min/1.73m 2 ) and impaired allograft function (GFR<60 mL/min/1.73m 2 ) as well as between patient groups according to donor type (living donor-LD and cadaveric donor-CD). Results: Overall cRBF in our patient group, as measured with ASL, ranged between 85 and 335 mL/100 g/min (mean 190.05 ± 67.62 mL/ 100 g/min). Mean cRBF in patients with good allograft function was significantly higher than in patients with impaired allograft function (225.91±64.38mL/min/100g vs. 146.22±41.84mL/min/100g, p=0.005), showing a highly significant correlation with GFR in all subjects (r=0.67, p=0.002). Mean GFR value in patients with LD was 58.30 ±14.86mL/min/1.73m 2 and with CD allograft was 66.05±15.80 ml/min/ 1.73m 2 ; mean cRBF in patients with LD was 168.36±60.00 ml/min/ 100gr and with CD was 216.56±70.17 ml/min/100gr-both parameters suggested no statistically significant difference in the values between groups (p=0.274 and p=0.115 respectively). In the binary logistic regression and ROC curve analyses in order to predict GFR values in all patients, cRBF showed statistically significant diagnostic efficiency in distinguishing allografts with good or poor function (p<0.05), with a high area under the ROC curve (AUC 0.859, p=0.007), the sensitivity of 73.0%, and specificity of 88.9%. Conclusion: Cortical perfusion as non-invasively measured by ASL-MRI differs between patients with good and impaired allograft function and correlates significantly with its function. Purpose: Echogenic debris on ultrasound has been considered as an indicator of infection. Our local practice when finding echogenic debris within the urinary tract in paediatric outpatients is to obtain urinary specimens for microscopy and culture analysis. We wished to evaluate our current practice to ascertain its effectiveness and take an opportunity to look for ways to improve. Materials and Methods: A retrospective data collection using search terms, echogenic urine, debris and specimen identified 77 paediatric outpatients who had had echogenic urine reported on their ultrasound between January 2021 and December 2021. Their electronic patient records were reviewed to look for results of specimens received at the lab. Results were classified indeterminate if two organisms were detected (suggesting contaminant) or pyuria without growth found. Results: 77 paediatric outpatients identified with age range 0-16. 51/77 (66%) patients had urinary specimens analyzed at the laboratory. 17/51 (33%) had positive specimens, 24/51 (47%) had negative results and 10/ 51 (19%) were indeterminate. 33/51 (65%) specimens were cultured. 15/ 33 (45%) grew one organism. 10/33 (30%) were E Coli. 6/33 (18%) had mixed growth, 12/33 (36%) had no growth. Discussion and Conclusions: Echogenic urine on ultrasound is not normal but its clinical significance in relation to infection is yet to be established. It can help identify some patients. Our work identified that not all patients with echogenic urine had specimens sent in line with usual practice. This was due to samples not being accepted by the laboratory, samples not being taken during clinic and parents being asked to drop off specimens to the GP. Our local laboratory normally would culture all paediatric urine samples, however Covid-19 restrictions has prioritized cultures on microscopy or urine dip positive samples only. Steps to improve our practice include discussion with ultrasound practitioners to encourage accurate and timely specimen collection and requesting the lab to culture all paediatric specimens. We will further evaluate our practice by reviewing patient records to ascertain whether patient were symptomatic or already on antibiotic treatment at the time of examination, or had structural urinary tract abnormalities. This will help streamline higher risk patients and utilize our resources more effectively. Purpose: The aim of this study is to evaluate differential renal function (DRF) in magnetic resonance urography (MRU) in comparison to dynamic renal scintigraphy (DRS). Material and Methods: The study included 46 (n=46) pediatric patients who underwent dynamic renal scintigraphy due to various clinical reasons. Magnetic resonance urography was performed within no more than 6 months interval, in which no urinary tract infection was detected and no surgical intervention was performed. Renal scintigraphy studies were assessed by nuclear medicine specialist and the results were retrieved from patients' medical history. MRU examinations were blindly evaluated by radiologist. Differential renal function was calculated using medical software Parametric MRI (pMRI). The results were submitted for statistical analysis. Results: Dynamic renal scintigraphy and magnetic resonance urography were performed in 46 (n=46) patients between 0 and 17 years old. The most frequent indication for the examination was hydronephrosis, which occurred in 22 patients (47.82%). The average value of DRF for the right kidney according to DRS was 52.6 +/-18.3 (range: 24-100%) and according to MRU 52.4 +/-19.7 (range: 14-100%). For the left kidney mean DRF was 47.4 +/-18.3 (range: 0-76%) and 47.6 +/-19.7 (range:0-86%) in DRS and MRU respectively. The correlation coefficient indicated highly significant correlation between these two methods.

Conclusions: According to our study, there are no significant differences between MRU and DRS in calculating differential renal function. Magnetic resonance urography should become an important part of diagnostic imaging in children as it provides both morphological and functional data without exposure to ionizing radiation. Purpose: Renal artery thrombosis is a rare, serious, and typically early renal transplant complication. Its prevalence in adult renal allograft recipients is estimated at 0.4% and only sparse cases in pediatric patients have been reported. The known risk factors include hyperacute rejection, technical errors, vascular injury during surgery, stenosis or kinking of the artery, vasculitis or external compression. Segmental infarction is even more rarely described, possibly due to limited symptomatology and diagnostic difficulties, however a ca. 5% prevalence was reported in a center performing routine radionuclide renal scanning in the early postoperative period. The aim of this case report is to present the possible application of contrast enhanced ultrasound (CEUS) in diagnosing and monitoring renal allograft segmental artery thrombosis in children. Methods: In two pediatric renal transplant recipients aged 5-and 14years old CEUS and contrast-enhanced computed tomography (CT) studies were performed in the early postoperative period due to segmental artery thrombosis of the grafts suspected in the routine Doppler ultrasound monitoring. Results: In the 5-year-old boy CEUS demonstrated a hypoperfused region ca. 3,5 x 2,5 cm large, located in the lower pole of the transplanted kidney. The impaired perfusion was subsequently confirmed in CT and intra-arterial thrombolytic therapy was commenced. The treatment's effects were monitored using CEUS the follow-up study on the next day showed a substantial decrease in the size of the hypoperfused region, and two weeks later only a small pathological area remained visible. In the 14year-old boy CEUS showed impaired perfusion of the cortex in the upper pole of transplanted kidney, which was confirmed in CT. The patient received thrombolytic therapy, which was monitored using CEUS, however no change in the abnormal region was noted during two weeks of follow-up. Conclusion: We describe the imaging features segmental renal allograft infarction in sonography, including CEUS. As demonstrated in the two cases CEUS can be effectively used to diagnose segmental allograft infarction in pediatric patients and to monitor thrombolytic treatment. Future large studies are needed to determine the incidence and clinical implications of this early complication among childhood renal graft recipients. Introduction and objectives: Enlarged scrotum is a relatively common complaint in the neonatal period and in young children. It covers different etiologies, usual and unusual. Although the main causes are benign, the remote possibility of a malignant tumor constitutes anxiety for parents and pediatricians. In this pictorial essay, we will present important scrotal pathologies of this age group, usual and unusual, detailing their main ultrasound findings for the wider knowledge of radiologists. Methods: The study uses different cases from the Pediatric Radiology group at our service, to illustrate and show details of the usual and unusual differential diagnoses, of scrotal enlargement in newborns and young children, such as: -Mature testicular teratoma; -Testicular cyst; -Acute idiopathic scrotal edema; -Meconium pseudocyst; -Extravaginal antenatal testicular torsion; -Hydrocele; -Inguinoscrotal hernia; -Encaspsulated hematoma. Discussion: Different clinical conditions and neonatal and pediatric pathologies can lead to a scrotal enlargement without specific clinical signs, giving the radiologist a fundamental role in the diagnostic management of these patients. Benign causes are the majority of these cases, with neoplasms being uncommon. Scrotal enlargement can occur from both intratesticular and extratesticular lesions. Among testicular lesions, we can mention neoplasms, cysts and torsions. Hydrocele, hematoma, inguinal hernia, meconium pseudocyst and acute idiopathic scrotal edema represent extratesticular causes of scrotal enlargement. Faced with such diverse pathologies and with wide therapeutic options, knowledge of the main imaging findings by the radiologist is essential for correct diagnosis and treatment. Conclusion: Ultrasonography associated with the Doppler study represents the main diagnostic tool in the context of scrotal enlargement in neonates and young children, as it does not use ionizing radiation, allows for the distinction between intratesticular and extratesticular diseases, with quick, non-invasive, real-time diagnosis.

Christopher Ng 1 , Nasim Tahir 1 1. Leeds Children's Hospital, Leeds, United Kingdom

Background: Lymphatic malformations are benign vascular lesions stemming from abnormal development of the lymphatic system. Depending on the location and extent of involvement, their presentation may mimic other disease processes and their subsequent management strategy can vary widely. Case report: We describe a case of an 11 year-old patient who was referred to a tertiary children hospital with a 3 week history of progressive dyspnea and petechial rash throughout his thorax. On admission radiographs, he was found to have pericardial and bilateral pleural effusions which were drained. Subsequent multi-modality imaging and in particular on MRI, showed diffuse cystic soft tissue abnormality throughout his upper body with further lesions in spleen, kidney, and multiple bones. He was thought to have with diffuse lymphangiomatosis. The biopsies performed at multiple involved sites did not reveal a malignant process. Initial histological analysis was suggestive of a vascular malformation which was confirmed on subsequent immunohistochemistry. His primary issue was recurrent and difficult to treat pericardial and pleural chylous effusions. Multiple different treatment strategies including repeated drainages, diet modification, total parenteral nutrition with octeotride, and embolization of his thoracic duct at lymphangiogram did not produce long-lasting therapeutic benefit. His case was discussed throughout among multiple teams, including the vascular anomalies MDT. Other therapies including sirolimus and eventually bevacizumab were trialed. However, these failed as well. The patient eventually passed less than a year later from worsening cardiorespiratory failure secondary to the aggressive thoracic involvement. Discussion and conclusion: Currently, there are no curative therapies for diffuse lymphangiomatosis and treatment options are primarily directed at managing symptoms usually in a stepwise fashion. In cases of solitary and symptomatic lesions, local treatment options including surgical excision, sclerotherapy or radiotherapy are possible. However, in more extensive and difficult to control disease, a multidisciplinary approach employing a range of treatment approaches are required.

Orsolya Szalmás National Institute of Mental Health, Neurology and Neurosurgery, Budapest, Hungary

Background and Purpose: Vein of Galen malformations (VOGM) are rare vascular malformations arising from persistent shunting of primitive choroidal vessels into the median prosencephalic vein of Markowski. The malformation develops before birth and becomes clinically evident soon after birth due to the shunting causing high-output cardiac failure and pulmonary hypertension. In addition, there is often hydrocephalus secondary to compression of the aqueduct. VOGM accounts for 1-2% of all intracranial vascular malformations but in the pediatric age group 30% of cerebral vascular malformations is VOGM. Our goal was to compare the success of the endovascular treatment with the clinical outcomes. Material and Methods: At the Hungarian National Institute of Mental Health, Neurology and Neurosurgery we could retrospectively collect 19 cases (N=19) between 2001 -2020. Most infants were diagnosed by ultrasound, after birth (N=11) or antenatal (N=6), however in 2 cases diagnosis was already made with intrauterin MRI. Because of the severe clinical symptoms, DSA was performed in the first days of life. DSA confirmed and demonstrated the complexity of the malformation, particularly the feeding vessels. According to international guidelines endovascular treatment was carried out in all but one case. After treatment we followed-up our patients by DSA and MRA for a 3-5 year-long period. Results: Symptoms mainly included tachypnea, abnormally enlarged head due to hydrocephalus, seizures and headaches. 1 baby had spontaneous closing of the shunt by clot formation. Unfortunately, 1 case was lethal before the endovascular treatment. In 9 cases, multiple embolization procedures were needed for complete correction, however in the rest of the cases (N=8), a single embolization procedure was enough for complete closing. Intracranial and intraventricular bleeding happened only in 3 cases. Just 1 symptomatic bleeding needed urgent neurosurgical intervention but the other 2 cases were recovered by conservative therapy. Nevertheless, our children's survival rate was 100% and their clinical outcomes were excellent: only 5 children had minor neurological deficits but even these patients went on to live normal lives during our follow-up period. Post treatment imaging findings correlated with the good clinical outcomes. Conclusion: Endovascular treatment of VOGMs is relatively safe and yields excellent results in the hands of a highly experienced interventional radiologist. Post treatment imaging findings predict and correlate with good clinical outcome. Introduction: Slipped capital femoral epiphyses (SCFE) is a common pediatric hip disease. SCFE is associated with the risk of disability, osteoarthritis and impingement deformities. MRI-based 3D-models would offer a radiation-free method for patient-specific preoperative planning. Therefore, we investigated (1) feasibility of MRI-based 3D-models of the hip (2) feasibility of 3D printing and 3D impingement-simulation using MRI-based 3D-models (3) postoperative slip angle of symptomatic patients with SCFE. Patients and Methods: A retrospective, radiographic study involving of 10 symptomatic patients (10 hips) with SCFE was performed. Mean age was 13±2 years and 50% were male patients. Six patients had severe SCFE (four had moderate SCFE), two patients had unstable SCFE. All patients underwent preoperative hip MR (2016) (2017) (2018) (2019) with pelvic coronal high-resolution images (T1 VIBE or T1 Starvibe). Slice thickness was 0.8-1.2mm. Semi-automatic MRI-based 3D segmentation was performed using software AMIRA. 3D printing of 3D-models was performed. The virtual 3D models were tested using specific software for dynamic 3D impingement-simulation. All patients underwent open surgical treatment: eight hips underwent modified-Dunn-procedure, while two hips underwent surgical hip dislocation. Results: (1) MRI-based 3D segmentation was feasible in all patients (100%, duration of 4.5 hours, mean 277±52 minutes). (2)3D printing of the hip 3D-models was feasible in all patients (100%). 3D models were considered helpful for preoperative planning of open hip preservation surgery by the treating surgeons. Dynamic 3D impingement-simulation was feasible in 6 patients (6 hips) and enabled visualization of femoral and acetabular impingement location. (3) Slip angle improved significantly (p<0.001) from preoperative 54±15°(40-70) to postoperative 4±2°(2-10). Conclusion: MRI-based 3D models of the hip for SCFE patients were feasible and postoperative radiographic outcome was good. 3D-models can be used for 3D printing and for impingement-simulation. This could aid for patient-specific preoperative planning and could improve the understanding of this deformity. 3D printed MRI-based models are radiation-free and could be used instead of CT-based 3D-models for simulation of open hip preservation surgery (mock surgery) such as femoral osteotomy or modified-Dunn-procedure. The wrist was injured most commonly with 26 fractures, average patient age 7 years. The most common MOI was falling from the trampoline (42.3%). Around the knee there were 19 fractures, 16 (84%) involved the proximal tibia. These fractures most often resulted from awkward falls on the trampoline (68.8%, 3 cases involved an older person falling on the child). Most children (68.8%) were preschoolers. 2 children had knee MR after normal radiographs: a 6 year old had a proximal tibial metaphyseal fracture and a 15 year old a lateral meniscus tear. Head and spine injuries were uncommon: 4 children fell from a trampoline and presented with head injury. CT brain revealed 2 occipital fractures. 10 children had spine radiographs. 2 progressed to MR for ongoing pain. Thoracic spine compression fractures were seen in 2 children: 1 fell from the trampoline, 1 was doing tricks. Discussion and Conclusions: It is recommended that children <6 years should not use home trampolines, due to the risk of injury; falling awkwardly both on and from the trampoline, and bouncing with another person in particular. Mechanically, axial loading forces are responsible for many resulting skeletal injuries. The prevalence of proximal tibial metaphyseal fractures in young children injured on trampolines is oft cited. Failure to follow safety advice can result in serious injuries of the head and spine. Our study supports previous published data: the appendicular skeleton is most vulnerable to trampoline injuries. Upper limb injuries more often occur falling from the trampoline, whilst lower limb injuries typically follow falls on the trampoline itself. Purpose: To date, two methods are available to quantify bone mineral density (BMD) in children presenting a risk of osteoporosis: quantitative computed tomography (QCT) which provides separately cortical and trabecular values and dual X-ray absorptiometry (DEXA) which provides global BMD values. We aimed to assess both correlation and agreement of BMD results between QCT and DEXA. Material and method: We reviewed all lumbar spine DEXA and QCT examinations performed within a three-month interval, as part of routine protocol in five-to-eighteen-year-old patients followed in a reference center between 2013 and 2019. BMD results were compared with the current available references and gave the Z-score (number of standard deviations compared to mean BMD for same age-and-gender-matched reference values). Correlation analyses were made between BMD results (DEXA BMD versus cortical and trabecular QCT). Agreement analyses were made between Z-score results (DEXA versus trabecular QCT). Z-score below or equal to -2 defined low BMD. Results: Among 246 patients, 26 were excluded for technical problems and 220 patients were included (10,6 ± 3.2 mean age, 137 girls, with 22% of hepatobiliary diseases and 39% of neuromuscular diseases). BMD correlation was low, especially between DEXA and trabecular QCT (r = 0.50). Z-score agreement was slight with lower Z-score in QCT (kappa: 0.04; 95% CI: 0.01, 0.07. Mean bias: -2.2). Additional analyses using alternative references for QCT showed better agreement (kappa: 0.37; 95% IC: 0.24, 0.51. Mean bias: -0.4). Conclusion: DEXA and QCT disagreed to evaluate BMD in children. By using standard references and Z-score, QCT seems to find more patients with low BMD, which raises the question of the pertinence of these QCT references. Therefore, BMD QCT should only be used at present for the follow-up of patients by comparison to each patient's own baseline. Objectives: To evaluate the necessity of contrast agent use in the MRI examinations of the sacroiliac joint in children and the efficacy of diffusion-weighted imaging (DWI) sequences in evaluating normal and inflamed areas. Patients and Methods: Sacroiliac joint MRI were evaluated in 54 patients with sacroiliitis and 85 controls by two pediatric radiologists. The sacroiliac joint space and surrounding bone marrow on each imaging sequence were examined. The presence of subchondral bone marrow edema in short tau inversion recovery (STIR) sequences and contrast enhancement in the sacroiliac joints were considered as active sacroiliitis. The DWI data were transferred to the workstation, and six apparent diffusion coefficient (ADC) measurements were taken from each sacroiliac joint (superior, middle, and inferior portions of the sacral and iliac bones) in all the patients with diagnosed sacroiliitis. A total of 648 areas were evaluated, and ADC measurements were performed in all areas in the sacroiliitis group. In the control group, two ADC measurements were made from each sacroiliac joint (iliac and sacrum), and a total of 340 areas were evaluated based on ADC values.

The STIR and post-contrast T1 weighted sequences were compared to detect pathological areas in patients with sacroiliitis. The sensitivity, specificity, positive predictive value and negative predictive value of the STIR images were calculated as 96%, 97%, 95%, and 98%, respectively in reference to the contrast-enhanced images. The mean ADC values were 1.35 x10-3 mm 2 /s (SD: 0.21) in the bone marrow areas in patients diagnosed with sacroiliitis. The mean ADC values of the normal bone marrow was 0.44x10-3 mm 2 /s (SD: 0.71). Conclusion: DWI is a short and effective MRI sequence that makes important contributions to the diagnosis of sacroiliitis in children without the need for a contrast-enhanced examination. It also prevents misdiagnosis the evaluation of sacroiliitis with ADC measurements in the immature skeleton.

directly genotyped SNPs in addition to imputed SNPs. COL11A1 has previously been associated with acetabular dysplasia and osteoarthritis (4, 5) . Conclusion: This large, genome-wide case-control study indicates an association between COL11A1 and patients with DDH, and is an important contribution to investigating the etiology of DDH, with further research needed. Neck masses may present a diagnostic dilemma in the pediatric population as the differential diagnosis is relatively broad. Common congenital masses in the neck include thyreoglossal duct cyst, branchial cleft cyst, dermoid cyst, vascular malformations and hemangiomas. Internal jugular vein aneurysm in neonate is a very rare entity, with almost no case reported in this age group. Venous aneurysms are usually detected late, as they are asymptomatic in most cases. Thromboembolic complications including spontaneous thrombosis in cases of jugular venous aneurysm are reportedly rare. We presented an unusual finding of prenatally formed internal jugular vein thrombosis (IJVT) in a female neonate patient who presented with a cervical mass on the right side. A 3-day-old neonate were referred to our hospital for further evaluation and treatment of prenatally seen unilateral neck mass. Prenatal ultrasound indicated a cystic appearance of the mass, so a differential diagnosis was branchial cleft cyst or lymphatic malformation. Asymmetry with minor tumefaction of the right side of the neck was clinically seen. Ultrasound examination was done and hypoechoic formation without CDS was observed in the lumen of the focal sacculary dilated internal jugular vein. IVJ aneurysm with thrombus formation was suspected. After that an additional MR examination was performed where the diagnosis was confirmed. Laboratory analyses and abdominal ultrasound were within physiological limits. Multidisciplinary decision was made for a conservative approach and reevaluation after 3 weeks. On US follow-up the thrombus mass was smaller until complete disappearance on US examination after 2 months. Screening for thrombophilia and prothrombin gene polymorphism were negative. An excessive birth trauma is postulated as a likely cause of the vascular malformation in the newborn period, but there was no history of birth trauma in our patient. Also, this neck mass was seen even prenatally. Early misdiagnosis is often related to lack of familiarity with the pathologic entity. To our knowledge there are no observed cases of prenatal thrombus formation in the internal jugular vein aneurism. Although it is a very rare entity, it should be included in the list of the differential diagnosis in cervical masses of newborns. Ultrasound examination as first line imaging modality can quickly and easily evaluate the neonatal neck mass and help us decide on further imaging or help clinicians to decide on a therapeutic option.

Palina Marakhouskaya 1 , Tamara Bolbas 1 1. National practical and scientific center for pediatric surgery, Minsk, Belarus Introduction: The term hyperostosis is used to describe conditions in which there is an enlargement of the outer portion of bones. Prostaglandin-induced hyperostosis commonly involves diaphysis of long bones of upper and lower limbs, clavicles, ribs, scapulae and must be differentiated with a variety of diseases, including vitamin deficiencies, Caffey's disease, multifocal osteomyelitis. Prostaglandin E courses (PGE) therapy are now commonly used to maintain the patency of ductus arteriosus in neonates with ductal-dependent congenital heart defects (CHD). Aim: To determine the minimal injected dose of PGE at which there is a risk of developing prostaglandin-induced periostitis in infants with ductal-dependent CHD. To explore the presence of additional factors of cyanotic CHD correlating with hyperostosis development. Materials and methods: Forty-eight infants with ductal-dependent CHD and previous preoperative PGE infusion (>2 days) who underwent reconstructive cardiac surgery were retrospectively included and separated into two groups. The study group counted 20 patients (6 female) from 2014 to 2021 with inclusion criteria of PGE-induced hyperostosis of long bones, diaphysis of upper and/or lower limbs, clavicles, ribs, diagnosed radiologically by X-ray examination after. We haven't found any study group as big as in this research in published literature. Patients remaining have been included to the control group (28 patients, 13 female). Patients with hyperostosis of any other localization were excluded. Results: The average age at the moment of hospitalization in the study group counted 8,9 days 95% Cl -0,44 -18,24 days with no significant difference (Mann-Witney P = 0,6936) from the control group with average 2,25 days Cl% 1,58 -2,92 days. At the moment of hospitalization, the average weight counted 2992,2 grams CI 95% 2579,9 to 3264,4, Shapiro test approved normality of distribution. The control group's average weight was 3114,2 grams CI 95% 2892,0 to 3336,3. T-test (assuming equal variances) showed no significant difference between two groups (P = 0,307). ROC-analysis was performed to determine minimal injected dose, in which there is a risk of developing prostaglandin-induced periostitis. Estimated data showed that if the injected dose had increased to 172,5 nanogram per kilo per minute (2484 microgram per kilo), hyperostosis would likely appear in 9 patients out of 10, AUC 0,918, P<0,001, with sensitivity 90 and specificity 92,9. Conclusion: It is essential to understand patients' anamnesis, especially comorbidity and medication administration records, in which PGE administration comes to the fore. Prostaglandin-induced hyperostosis is dose-related. ROC-analysis showed that if the injected dose had increased to 172,5 nanogram per kilo per minute (2484 microgram per kilo), hyperostosis would likely appear in 9 patients out of 10. Purpose -To discuss the several entities affecting the spine and vertebrae regarding their pathophysiology, clinical presentation and treatment; -To demonstrate their radiological appearance, mainly in computed tomography (CT) and magnetic resonance (MR) imaging; -To propose an illustrative guide for reference, highlighting their differential diagnoses in imaging. Methods/Background: Masses of both benign and malignant origin can occur in the spine and vertebrae, as well as in the paravertebral region, with subsequent vertebral and/or spine invasion. Although definitive diagnosis is established through anatomopathological evaluation, imaging appearance may help narrow the diagnosis and allow prompt management. Results/Findings: The following teaching cases from our radiology department will be presented, with their respective imaging aspects and brief review of clinical and pathological features: -Medullary Ganglioneuroblastoma; -Medullary Astrocytoma; Purpose: To describe and illustrate the imaging pearls and pitfalls of normal development, variants and pathological findings pertaining to the paediatric knee. Material and Methods: The paediatric knee joint is commonly imaged with either plain radiographs or MRI to evaluate for traumatic, inflammatory, developmental or neoplastic conditions. Traumatic conditions occur more commonly in older children/adolescents due to increased participation in sports whilst conditions such as infections or inflammatory arthritis are more often observed in younger children. The patterns of paediatric knee injury are similar to the adult population in older adolescents, but differ in skeletally immature patients where there is relative weakness at their unossified physes and apophyses around the knee, resulting in different biomechanical forces on ligaments and bones. Benign and malignant tumours occur less commonly but are important causes of knee pathology. Results: Normal knee development and variants of ossification, which can be confused for injury, such as posterior femoral condyle ossification site, fibrous cortical defects, etc. or contribute to pathology, such as discoid meniscus, will be described. Congenital conditions specific to the paediatric knee including angular/alignment deformities, genu recurvatum, congenital dislocation of knee and skeletal dysplasias are illustrated. Common injury patterns of the paediatric knee focusing on mechanisms of bony/physeal and soft tissue injuries are discussed. Common inflammatory, infective and neoplastic conditions of the paediatric knee such juvenile idiopathic arthritis, chronic recurrent multifocal osteomyelitis, Langerhans Cell Histiocytosis, haemophilia and pigmented villonodular synovitis, etc., are also described. Conclusions: A thorough knowledge of normal and pathologic imaging findings of the paediatric knee is essential for radiologists to make important diagnostic and management contributions. Purpose: To illustrate the findings of multimodality imaging exploration of musculoskeletal infection (including bones, joints and soft tissues) in pediatric population. Material and methods: Population includes neonates, infants and children referred to our department for the investigation of probable musculoskeletal infection. Plain radiographs and ultrasound was the first line imaging investigation. In most cases imaging investigation was completed with MRI, in order to set the final diagnosis, determine the extent of infection and depict complications that might need intervention. Results-Conclusions: Typical imaging features of musculoskeletal infections with x-rays, ultrasound and MRI are presented in detail, along with clinical information and short-term and long-term outcome. Purpose: IRefer guidances suggests MRI is the modality of choice in the investigation of paediatric back pain 1. In our institution both MRI and bone scintigraphy are currently used in the diagnostic pathway. The purpose of this study was to review all bone scintigraphy studies performed for the investigation of paediatric back pain. Materials and Methods: All bone scintigraphy studies performed in a 14-year period from 1/04/2007 -01/04/2021 were reviewed. Inclusion criteria: Age 16 or under; Bone scintigraphy study performed for: Back pain (cervical, thoracic, lumbar and sacral), back pain and scoliosis; Available MRI study or report for review. Exclusion criteria: No available MRI report or study images for review Bone scintigraphy study performed for; Possible metalwork complication post scoliosis correction surgery, Lower limb, Hip or pelvic pain or the investigation of bony metastasis in cases of known primary malignancy. Results: 182 studies met the inclusion criteria. 17 (9.3%) studies had no plain film imaging for review prior to bone scintigraphy. 32 studies (17.6%) had no MRI study prior to bone scintigraphy. In many cases these studies were requested at the same time with the same clinical details. In 116 (63.7%) patient cases both MRI and bone scintigraphy demonstrated no abnormality. In 9 cases (4.9%) both MRI and bone scintigraphy identified the same abnormality. These constituted 5 cases of pars defects, 1 osteoid osteoma, 1 osteoblastoma and two cases of oedema with corresponding increased tracer activity in 1) Spinous process and 2) superior endplate. In 17 cases (14.7%) MRI picked up possible abnormalities in the context of a normal bone scintigraphy study. Of the 17 cases, 8 cases were pars defects later confirmed on CT, 4 were suspected pars defects 2 of which were disproved with CT, 2 had no follow up imaging. The remaining 5 cases in this category were: 4 cases of abnormal vertebral body or endplate signal not followed up and 1 case of SIJ arthropathy. There were 18 (15.5%) cases where MRI suggested an alternative MSK cause for back pain: Bertolottis, Degenerative disc disease with annular tears and facet joint arthropathy. In 15 (12.9%) of cases an incidental finding was discovered on MRI (renal dilation, solitary kidney, tracer retention, syringomelia, spinal cord tumour, Scheuermann's, pleural effusion). In 8 cases (6.9%) the bone scintigraphy identified an abnormality or was reported as equivocal in the context of a normal MRI. In 2 cases both the pre and follow-up MRI were normal. In 2 cases the MRI was performed after the nuclear medicine study and reported as normal and the nuclear medicine findings were dismissed. In 4 cases with normal MRI studies, no further imaging was undertaken. Conclusion: Our study has shown no added benefit in performing bone scintigraphy in the investigation of paediatric back pain in the context of a normal MRI study.

Purpose: Tuberous sclerosis complex (TSC) is a rare genetic disease that presents with variable neurocognitive manifestations. This study investigated longitudinal dynamic changes in whole-brain perfusion in children with TSC using arterial spin labeling (ASL) perfusion MRI and their correlation with neurodevelopmental delay. Material and Methods: This was a single-center retrospective longitudinal cohort study of children with TSC who underwent at least three interictal brain ASL/FLAIR MRI examinations before 7 years of age, including one before 2 years, between January 2012 and January 2021. Children were divided into two groups according to their last available neurodevelopmental assessment as having either no/mild or severe delay. For each patient MRI scan, 9-12 age-matched control cerebral blood flow (CBF) maps were collected. Whole-brain gray matter CBF values were extracted for all patient scans and age-matched controls and the CBF ratio between patients and controls was used to study longitudinal changes in whole-brain CBF and their association with developmental delay. For each patient, tubers were manually segmented on a FLAIR MRI sequence and tuber characteristics (count, volume, location) were recorded. Results: Thirteen children underwent 3 to 6 serial ASL/FLAIR MRI scans between two months and seven years of age, totaling 53 scans. Eight children developed no/mild developmental delay and five severe delay. On linear regression analysis, children with severe developmental delay showed a significant decrease in whole-brain CBF ratio with age (p = 0.01), which was not present in the no/mild delay group. Group comparisons of whole-brain CBF ratios by age range showed that these differences only became apparent after two years of age. There were no significant group differences in tuber count, volume or location to account for the observed differences. Conclusions: These findings emphasize the importance of early prognostication and possible intervention in children with TSC. ASL perfusion MRI appears to be a promising technique to improve our understanding of the clinical course of TSC. Purpose: To illustrate the radiological findings of an unusual onset of haemophilia B in an infant and to demonstrate how a correct integration of imaging, clinic and laboratory findings can lead to a correct diagnosis and prompt intervention.

Material and Methods -Results: It is described the case of a 6-monthold infant who presented at the emergency department for a few hours of inconsolable crying. There was no history of trauma and the physical examination found no signs of hematomas or lesions suspected for accidental or non-accidental trauma. X-ray examinations of the chest, abdomen and limbs were normal. An abdominal ultrasound was performed revealing no abnormalities. A cranial CT scan revealed no intracranial bleeding or masses. The neurological examination found some radiculopathy signs, so that an MRI of the spine was requested. The MRI examination showed an epidural hematoma extending from C1 to the sacrum with evidence of thoracic spinal cord compression. Mixed signal intensity of the hematoma suggested both acute and subacute components. A complete blood analysis finally revealed a coagulopathy due to factor IX deficiency, leading to the diagnosis of Haemophilia type B. The infant was immediately treated with factor IX and had a good neurological recovery in a few days. The MRI revealed a complete resolution of the haematoma in about two weeks. Conclusions: Spinal epidural hematoma (SEH) is a neurosurgical emergency characterized by the extravasation of venous blood into the epidural space. Spontaneous SEH are rare with an estimated incidence of 0.1/ 100000 in the overall population annually; the incidence in children is unknown. Clinical presentations typically include neurological dysfunction and/or back pain, but clinical diagnosis is hard to make in infants, who usually present with non-specific symptoms such as irritability or crying. Cross-sectional imaging with MRI or CT scan is always diagnostic. There is no consensus for the treatment of SEH. Prompt diagnosis and replacement therapy may prevent surgical intervention but decompressive laminectomy may be needed in cases of rapidly progressing signs of cord compression. In our case surgery was not considered because of the improving neurological status. This case demonstrates that an inconsolable crying of an infant can be a challenging situation to face in an emergency department but the correct use of imaging techniques is essential to make diagnosis and act promptly. Purpose: <Addendum> refers to the inclusion of new information in a radiology report that is already complete, which may provide a variety of details, varying from correction of a simple error e.g. a typing erratum, to notification of significant errors e.g. missed findings or misdiagnosis. Determining frequency and characterization of addenda may help in understanding them, and ultimately may lead to improved clinical practice. We aimed to determine the frequency of different categories of addenda for paediatric brain MR reports. Methods: Retrospective review of the addenda of Brain Magnetic Resonance Imaging (MRI) reports from a large tertiary children's hospital was performed over six-month periods, October to March, spanning 2018 to 2021. A Radiology fellow and a Medical Doctor classified the addenda into previously published categories using their best judgement to place them into a single best category, and where necessary, into more than 1 category. Results: Out of a total of 13639 brain MRI reports, only 181 reports (1.33%) had an addendum. There were 152 reports with a single category of addendum, 22 reports with two categories of addendum and 7 reports with three categories of addendum. The number of errors according to categories were: Observational 88/13639 (0.65%); Interpretational 16/ 13639 (0.12%); Non-observational and non-interpretative 84/13639 (0.62%). Notifications to referring physician made up 29/13639 (0.21%). The most common observational errors were under reading of images in the region of interest: 34/13639 (0.25%) and missed incidental findings 23/13639 (0.17%). The time gap between the initial completed report and the addendum was: 87/181 (48%) < six hours; 32/181 (18%) 6 to 24 hours; 38/181 (21%) 1 day -7 days; and 24/181 (13%) scans: > 7 days. Conclusions: The overall proportion of addenda in brain MRI reports of children in our study was low, at 1.3%. Categorization of different addenda revealed the most common errors to be observational in 0.65%, including under-reading in the region of interest in 0.25%? appropriate measures can now be introduced in an attempt to minimize these further and improve MRI diagnosis in children. Other paediatric practices may choose to follow suit in evaluating their addenda and errors to improve practice.

PROPIONIC ACADEMIA CRISIS, A SPECIFIC DWI FINDING, CASE REPORT Khairy Abdella 1 1. Maternity and Children hospital, Nejran, Egypt Propionic academic is among the rarest metabolic disorders described in the literature. It is resulted from an inborn error in the catabolism of amino acids with accumulation of organic acids as a consequence of this error. This illness was especially manifested and discovered in early postnatal life with other forms seen later in the childhood period. It has a different clinical presentation with poor feeding, hypotonia as well as lethargy have been described in the early neonatal period, while mental retardation and global developmental delay as well as seizures are seen later in life. We present a case of a 6-month-old child already diagnosed in his early neonatal period with propionic acidemia currently presented with Propionic academic crisis in the form of frequent attack of seizures with unique DWI features in the form of bilateral symmetrical restricted diffusion in the subcortical & subinsular white matter that are specific to propionic acidemia crisis and does not relate to any vascular territory. This case report aims to reinforce this unique DWI criteria in the Propionic academic crisis. and/or atrophy and/or calcification, and with respect to whether ASL demonstrated the findings of SWS more or less conspicuously. Results and Conclusions: 31 children (55% male, mean age: 4 years, range: 0-16 years) had diagnostic ASL available for review and 22 of these (71%) demonstrated perfusion abnormalities. Of these 22 with perfusion abnormalities, 15 (68%) showed hypo-perfusion and 7 (32%) hyper-perfusion. The ASL abnormality matched presence and side of SWS findings on conventional imaging in 19 children (86%) -ASL showed the abnormalities more conspicuously in 16%, the same in 21%, and less conspicuously in 63%. The parietal lobe was involved in 77% of cases. ASL in SWS often shows increased perfusion during the early phase of the disease and decreased perfusion later when there is atrophy. Advantages of ASL include that contrast is not required, it is noninvasive, fast, repeatable and quantitative (3). ASL perfusion imaging is an advanced technique which may contribute to earlier diagnosis and more accurate prognostication of Sturge-Weber Syndrome, helping guide management and potential surgical planning. Background: Hirayama is a rare, mostly sporadic, monomelic amyotrophy. The typical clinical features include insidious juvenile onset and slow progression of unilateral or bilateral muscular atrophy with weakness of the forearms and hands with no sensory disturbances. The condition is caused by multiple episodes of subclinical trauma to the anterior horns of the cervical spinal cord during flexion. The limited dural sac laxity leads to chronic microischemic changes that can later be visualised on the specifically performed MRI. Case presentation: A 16-year-old girl presented with gradual right upper limb weakness and wasting in the distal muscles for the last two years. The neurological differential diagnosis included amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA) and advanced carpal tunnel syndrome. No orthopedic cause for the symptoms was found. Additionally, nerve conduction studies (NCS) and electromyography, genetic and neuroimaging studies were performed. Results: The MR of the cervical spine was performed native and with contrast enhancement. The first part of the examination was in neutral position of the neck, followed by imaging in flexion. Mild right-sided atrophy of the spinal cord was detected at the level of C5-C6 with a T2 hyperintense focus in the right lateral column. In the sequences performed in flexion enlargement of the dorsal epidural space was demonstrated with prominent flow voids. After contrast administration there was an enhancement from the level of C4 to the upper thoracic region. The NCS were consistent with axonal damage of the right ulnar nerve, combined with neurogenic changes of the right m. interosseus dorsalis I dexter and right m. extensor indicis. The genetic tests excluded amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). Conclusion: Even though it is considered a self-limiting disease, there are cases where the early diagnosis can limit progression or even decrease the degree of disability. The radiologist should be familiar with the specific MRI findings in Hirayama disease as the clinical onset usually occurs at the beginning of puberty. MRI during neck flexion increases the conspicuity of the typical imaging findings. Including this disease in the differential list is important for proper execution of the MRI examination. Mild TBI (mTBI) is the most common neurological damage in children that's why it is extremely important to identify and analyze biomarkers that can help in predicting patient's treatment and recovery in period of mTBI. Aim of this study is to verify a hypothesis that functional connectivity disturbances between intact cerebellum and DMN nodes are included in symptomatic manifestation of mTBI. Methods: 28 MR negative patients with mTBI were studied in age from 12 to 17 years (mean age -14.7 years). The control group consisted of 23 healthy children. All MRI studies were performed on a Philips Achieva dStream 3.0T scanner equipped with a 32-channel Philips dStream head coil. A 4-min rsfMRI gradient-echo echo planar imaging (EPI) sequence was acquired (TR=3000 ms, echo time [TE]=30ms, 80 dynamics with dynamic scan time = 3 s). fMRI data were processed using functional connectivity toolbox CONN. Results: No statistically significant differences in correlation strengths between control group and group of patients were detected as a result of DMN analysis. Seed-based correlation ROI analysis in control group revealed statistically significant (p <0.05) links between DMN regions and the following structural cerebellum parts: lower and upper semilunar lobes and flocculus. In mTBI group these correlations are not revealed (p = 0.39). Conclusion: The revealed changes in DMN neuronal connection and cerebellar regions in acute stage of mTBI patients can be an initial step of damages leading to cognitive deficit which can be developed in future in long-term period of injury. Aim of this study was to explore the dynamics of microstructure and brain metabolism parameters in children with severe traumatic brain injury (sTBI) and hypoxic-ischemic brain injury (HIBI). Materials and Methods: 8 patients (mean age = 12.5) with sTBI comprised group 1. 4 children (mean age = 13.6) with HIBI caused by drowning in fresh water. MR studies of patients from both groups were carried out twice: first -during the first seven days after injury (period 1); second -a month after injury (period 2). All studies were performed at Phillips Achieva 3.0T MRI scanner. DT MR images were acquired with diffusion gradients applied in 32 non-collinear directions. 1H-MRS voxel (TR/TE =1500 ms/ 40 ms, NSA = 128) was localized in left and right thalamus (for groups 1 and 2) and in brain stem (for group 2). Results: 1H MRS analysis in thalamus revealed significant decrease in dynamics of NAA/Cho value in group 1 (41% decrease) and absence in dynamics of this index in group 2. Significant increases in dynamics of ADC and FA values were found in corpus callosum in group 1. In group 2 we detected increase in dynamics of ADC value and NAA/Cho ratio in brain stem. Conclusion: The significant decrease of NAA/Cho dynamics in thalamus in group 1 may indicate an active NAA intake in synthesis in oligodendrocytes to restore myelin sheath. Dynamics of spectroscopy and DTI parameters in brain stem correlates with the restoration of CNS functions in patients after drowning. Purpose: Ulegyria is an under-recognized and under-reported potential sequela of hypoxic ischemic injury (HII) in full-term neonates. The unique mushroom-shape of the affected gyri in ulegyria is a result of volume loss at the deep portions of the sulci during hypoxic ischemic injury at this period in infantile neurodevelopment. Identification of ulegyria is important because of its close association with pharmacoresistant epilepsy and also for ascribing cause and timing of HII on delayed MRI scans. The purpose of this study was to determine the frequency of ulegyria and characterize the anatomical distribution of watershed injury in a large database of children who sustained HII at term and underwent delayed MRI scans. Materials and Methods: Patients with term HII patterns on MRI were analyzed for the presence of ulegyria. Frequency of ulegyria overall and for each pattern of HII distribution was determined as was the anatomic distribution of watershed injury. Results: Of the 731 children with term HII and cortical injury, ulegyria was present in 484 (66%). Ulegyria was most common in those cases with a combined watershed/basal ganglia-thalamic pattern (56%) and isolated watershed pattern (40%). Watershed injury in patients with ulegyria was most common at the posterior watershed (80.6%) and peri-Sylvian watershed (76.7%). Conclusion: Ulegyria was present in nearly two thirds of patients with term HII and cortical injury, and should be sought to support the diagnosis of prior perinatal HII, especially in the posterior and peri-Sylvian watershed. Previous literature has focused on the neuroimaging description and pathogenesis of ulegyria. Here, for the first time we describe the frequency of ulegyria and distribution of watershed injury in a large HII database. The implications of ulegyria can be significant for surgical decision making and for ascribing timing of injury to the perinatal period. Purpose -Review aspects of eye and orbital anatomy that are relevant to the emergency scenario; -Highlight the imaging findings of several orbital emergencies; -Conduct a brief review of clinical features and management of each condition. Methods/Background: Orbital emergencies are relatively frequent in the pediatric population. Clinical evaluation can be challenging due to little patient collaboration and family anxiety. Imaging assessment, mainly through computed tomography (CT) and magnetic resonance imaging (MRI) can provide diagnostic insight and help to plan surgical interventions and optimize clinical management. Results or Findings: 1. Anatomy of the Orbit and Eye: annotated radiological images 2. Imaging methods and diagnostic assessment: ultrasound, computed tomography and magnetic resonance imaging -Technical considerations -Recommended protocols 3. Several cases of pediatric orbital conditions from our Emergency Department. Imaging findings will be elucidated and followed by a brief review of clinical features and treatment / outcomes. Introduction: Remnants of the pharyngeal apparatus are the second most common congenital anomaly of the neck. Purpose: Review the normal embryological development of the pharyngeal system and its derivatives; Describe clinical and imaging findings of congenital anomalies of the pharyngeal clefts; Discuss differential diagnoses and treatment. Material and methods: We reviewed the literature, summarized it in a didactic approach and illustrated with images from our service. Results: The pharyngeal apparatus is a paired set of components in the cephalic pole of a 4-to 7-week-old embryo. It consists of 6 arches and 5 clefts, pouches and pharyngeal membranes. Derives many structures from the face and neck. extension, to detect complications, and to monitor progression through systematic follow-up. This study illustrates multiparametric MR imaging of OPGs based on a retrospective review of 35 children followed up in our institution. Common and unusual features of sporadic and neurofibromatosis type 1-associated OPGs are presented, as well as their post-treatment appearance. We also expose CNS-associated lesions in the event of NF-1. Finally, we provide elements of MRI sequences that may guide the diagnosis and reveal some predictive elements of progression.

A PICTORIAL CASE SERIES REVIEW OF PAEDIATRIC CRANIOSYNOSTOSES Faraz Arfeen 1 , Vidula Godhamgaonkar 1 1. Manchester University NHS Foundation Trust, Manchester, United Kingdom

Craniosynostoses are an important paediatric clinical entity that can lead to severe cosmetic disfigurement. Early diagnosis is key to effective management which could be conservative or surgical. Appropriate surgical management and multi-disciplinary input can help reduce morbidity and ensure satisfactory clinical/cosmetic outcome. With the evolution of CT scanners and reporting systems, 3-D reconstruction algorithms provide a detailed assessment for diagnosis and surgical planning. We present a retrospective review of several case studies encountered during our practice highlighting the different imaging features of craniosynostoses. Examples of cases include brachycephaly, scaphocephaly, trigonocephaly and more. We hope this pictorial review will serve as a refresher of the different craniosynostoses and highlight the advantages of using 3-D reconstruction.

Ebinesh A 1 , Alpana Manchanda 1 1. Maulana Azad Medical College, New Delhi, India MR imaging is the imaging modality of choice for neonatal encephalopathy. Radiological findings due to injury to the parenchyma of neonatal brain evolve over days to months on conventional MRI (cMRI)1,2. Moreover, T2W hyperintensity caused by parenchymal injury tends to be subtle due to inherent high T2W signal of the unmyelinated neonatal brain. Diffusion weighted imaging (DWI) is highly sensitive to the early changes in brain parenchyma even when cMRI shows no abnormality. We present the spectrum of diffusion abnormalities in 36 neonates with various causes of neonatal encephalopathy. MR imaging was performed on 36 neonates with a clinical diagnosis of encephalopathy within first 28 days of life. Of 36 neonates, 21 neonates had hypoxic ischemic injury (HII) out of which 4 neonates had imaging features of co-existing sepsis. Four neonates had coexisting HII with neonatal hyperbilirubinemia. Four neonates had CNS infection. Three neonates had features of hypoglycemic encephalopathy. Two neonates had encephalopathy secondary to inborn errors of metabolism. Two neonates with clinical diagnosis of HIE had normal MRI. In conclusion, recognizing the topographic distribution and patterns of diffusion abnormalities is valuable in the diagnosis and prognostication of various causes of neonatal encephalopathy. Objective: Benign epilepsy with centrotemporal spikes (BECTS) is one of the most common pediatric epileptic syndromes. Recent studies have shown that BECTS can lead to significant language dysfunction. Although, research has evidenced the role of the language circuits in BECTS, it is unclear how specific brain areas associated with language circuits show different change patterns in patients with this syndrome. Methods: Using the resting-state fMRI data in a group of 21 drug-naïve patients with BECTS, 34 drug-receiving patients with BECTS and 36 demographically matched healthy controls, we investigated changes of language function connection in BECTS. First, we selected 14 region-ofinterest (ROI) from the language circuits that were most relevant to language function based on meta-analysis. Then, correlation between seed points was conducted on the fMRI data. Finally, a whole-brain correlation analysis based on the seed points was performed. Results: Compared to healthy controls, BECTS had increased functional connectivity in the left lingual gyrus, right middle temporal pole, right inferior frontal gyrus triangle and left middle temporal gyrus. Increased functional connectivity was found in the left posterior medial frontal gyrus, the left superior medial frontal gyrus and the right transverse tempora gyrus while decreased connectivity was found in the left middle occipital gyrus and the right middle temporal gyrus in drug-receiving patients with BECTS. In drug-naïve patients with BECTS increased functional connectivity was found in the right precentral gyrus and left inferior occipital gyrus. Conclusions: These findings provide evidence of the BECTS-related functional connection patterns of the language circuits, and suggest that whole-brain large-scale network connectivity differences associated with language dysfuction in BECTS. Purpose -Review epidemiological and clinical features of rhabdomyosarcomas; -Highlight the spectrum of imaging findings in children with respect to histopathologic subtype and anatomical location. Methods/Background: Rhabdomyosarcomas are the most common sarcomas in children. They develop from primitive mesenchymal cells and can be found in several body sites. Imaging features vary according to histologic subtypes, primary location and age at presentation. There are three major histologic subtypes: embryonal, alveolar and pleomorphic rhabdomyosarcoma, the latter occurring exclusively in adults. Results or Findings: Several cases of rhabdomyosarcomas will be presented. Histologic subtypes, epidemiology, clinical features and imaging findings will be discussed according to their location: -Orbital; -Nasopharynx; -Mastoidal; -Perineal; -Testicular and paratesticular; -Vesical; -Retroperitoneal; -Parameningeal metastatic rhabdomyosarcoma. Conclusion: It is critical for radiologists to be aware of the main imaging features of rhabdomyosarcomas. Imaging has a place not only in diagnosis but also in staging and in the evaluation of tumor response and recurrence.

Jr USA 1979 A. Lassrich Germany 1979 J. Sauvegrain France 1982 C. Fauré France 1982 A. Giedion Switzerland 1983 E. Willich Germany 1984 R. Astley United Kingdom

Sweet United Kingdom 1990 D.R. Kirks USA 1991 A. Chrispin United Kingdom 1991 E.A. Franken USA 1991 D. Nussle Switzerland 1991 B.P. Wood USA 1992 W.E. Berdon USA 1993 W. Holthusen Germany

Kramer The Netherlands 2000 G. Stake Norway

Brunelle France 2007 R. Fotter Austria

The Dutch Group of Paediatric Radiologists, The Hague/The Netherlands 1981 G. Stake, Oslo/Norway 1982 A. Rubin

Magnetic resonance imaging assessment of inflammatory activity and mandibular growth following intra-articular TMJ steroid injection in children with JIA 2014 A. Slaar (The Netherlands), A clinical decision rule for acute wrist trauma in children

Prenatal magnetic resonance lung volumetry of congenital diaphragmatic hernia: Comparison with the clinical outcome and the necessity of extracorporeal membrane oxygenation

Magnetic resonance imaging findings as an indication of underlying genetic lesions in congenital malformations of the brain

Magnetic resonance imaging vs. positron emission tomography/computed tomography for detection of focal splenic lesions in paediatric and adolescent lymphoma at initial staging 2012 P. Xenophontos (Greece), Detection of primary sclerosing cholangitis (PSC)-type lesions in children with inflammatory bowel disease via magnetic resonance cholangiopancreatography: A relative risk measures analysis 2013 G. Pasztor (Hungary), The importance of pyelectasis: Report of a clinical study in progress

Increased risk of venous thrombosis of the arm with multiple peripherally inserted central catheters insertion in paediatric patients 2018 D. Dünger (Germany), Do we ned gadolinium-based contrast medium for brain magnetic resonance imaging in children?

Utrecht/The Netherlands 1996 P. Thomas, (ESPR) and K. Fellows (SPR) Boston/United States

SPR)

Bendik Kristoffer Slagsvold Winsvold 2,3,13 , Karen Rosendahl 14,15 1. Department of Orthopedic Surgery

Late detection in children can result in the need for major surgery instead of low risk abduction harness treatment. We aimed to explore the genetic background of DDH in order to improve diagnosis, management and long-term outcome. Material and methods: We used the large, ongoing, longitudinal Trøndelag Health Study (HUNT) database, established in Norway in 1984 (3). Case definition was based on ICD-9/-10 diagnoses of DDH, or osteoarthritis secondary to DDH, extracted from the National Patient Registry. Analyses were performed using SAIGE software, with covariates including sex, batch, birth year and principal components. We included only SNPs with MAF < 0.01, R2 > 0.8 and HWE p > 0.0001. Genome-wide significance level was set at p < 5x10-8. The study was approved by the regional ethics committee. Results: Analysis included 69,500 individuals

All of the images were in different and random orders, on both of the assessment occasions. The agreement was assessed using the interclass correlation coefficient and Bland Altman plots. Results: Patients' age ranged from 3 to 16 years, in which the mean of the chronological age was 9.3 years (± 2.9) and 9.8 years (± 2.7) in girls and boys, retrospectively. The inter-rater agreement for skeletal age determination was 0.984 for radiographs and 0.976 for MRI scans. using the G&P technique. For Observer 1, intra-observer agreement for radiographs and DXA was 0.993 and 0.983 respectively, and 0.995and 0.994 respectively for Observer 2. Plotting the raters readings against the line of equality shows no significant differences between readings acquired from radiographs and MRI scans. Conclusion: This feasibility study indicates that open compact MRI may potentially be used for skeletal age assessment

RADIOLOGICAL FINDINGS BEFORE AND AFTER CT-GUIDED THERMOABLATION

Dipartimento di Neuroscienze, Riabilitazione, Oftalmologia

Similar radiological findings were identified in all the patients: periosteal reaction, classical nidus, synovial hypertrophy, joint effusion and bone marrow edema. After CT-guided thermoablation, all these pathological findings solved. Conclusion: Recognizing the radiological features of intraarticular osteoma osteoid of the elbow is crucial for the good management of the pediatric patient

Department of Pediatric Radiology, Necker Children's hospital

Purpose: Sturge-Weber Syndrome (SWS) is a developmental disorder that includes angiomatosis of the face, the choroid of the eye and the leptomeninges, and may present with seizures, hemiparesis or developmental delay. A GNAQ gene mutation results in a venous dysplasia which produces focal venous hypertension and associated tissue responses. MRI is used for initial diagnosis and common intracranial findings include pial angiomatosis, dilated deep medullary veins, engorged choroid plexus, cortical calcifications and cerebral atrophy. Imaging is important to determine intracranial extent and progression, relevant to prognostication and surgical planning. Arterial Spin Labeled (ASL) perfusion is an advanced MRI sequence which can assess perfusion, without the need for contrast administration. This research evaluates the potential benefits of using ASL in the evaluation of SWS in children, using multiple examples from our institution. A recent consensus paper states the clinical need for ASL research in SWS and this is the first project to systematically assess ASL in Sturge-Weber Syndrome. Material and Methods: Two paediatric neuroradiologists working together, retrospectively evaluated ASL perfusion imaging of 31 patients with confirmed SWS from our institution and recoded when there was hypo-or hyper-perfusion. The presence and distribution of ASL abnormality was compared against the presence and side of pial angiomatosis

The remnants of the apparatus may present as a cyst, sinus tract or fistula. The sinuses and fistula manifest earlier, are identified by ultrasonography as hypoechoic pathways, and can be better characterized by fistulography or axial exams. Cysts are diagnosed in older children/young adults, with a cervical bulging and phlogosis if infected. By ultrasonography they present as a cyst, which may contain debris if infected and fluid attenuation on tomography and with hypersignal on T2 and variable signal on T1 by magnetic resonance. When infected, the cyst walls become thick and irregular, enhanced by intravenous contrast. Second cleft anomalies are the most frequent. They are located between the level of the mandible angle and the carotid bifurcation. First cleft anomalies are located above the level of the mandible, may be retroauricular or within the parotid gland, and its fistula may open in the external auditory canal. Third and fourth cleft anomalies are rare, infrahyoid. The third cleft cyst is located in the posterior triangle of the neck, while the fourth cleft cyst is located adjacent to or within the left thyroid lobe. As differential diagnoses we have: thyroglossal duct anomalies, dermoid cysts, thymic cyst, lymphatic malformation, necrotic lymph node, among others. Conclusion: Imaging exams are essential for the diagnosis and preoperative planning of congenital anomalies of the pharyngeal apparatus, as they are usually treated with complete surgical excision. Therefore, knowledge of these anomalies by radiologists, as well as their differential diagnoses, is of great importance.

Heena Chotai 1 , Khilesh Radia 1 , Vamsee Bhrugubanda 1 , Mandip Heir 1 1. University Hospitals Leicester, Leicester, United Kingdom Introduction: The cranio-cervical junction (CJC) is a complex biomechanical region of transition which is both anatomically and radiologically different to its adjacent structures. With the passage of a number of key elements, including the spinal cord and cervical vasculature, anomalies in this region can result in life threatening consequences. Hence, the cranio-cervical junction is an important review area, when reporting head or cervical spine imaging. The radiologist plays an important role in the identifying any incidental abnormalities at the cranial cervical junction. Aim: In this presentation, we outline the key anatomy of the cranial cervical junction and highlight significant incidental findings which may be overlooked. We will demonstrate the imaging appearances of a number of abnormalities that we have seen in our clinical practice including posterior fossa abnormalities/Chiari malformations that may be missed on spinal imaging, to segmental anomalies, normal variants and spinal pathologies that may be missed on cranial imaging. Conclusion: The cranio-cervical junction can easily be overlooked when reporting, and the cases reviewed have demonstrated the need to be vigilant. Purpose: To avoid anesthesia during MRI studies in young children. The idea of mother-child-combined MRI and it`s fulfillment is known from studies of the breastfeeding and swallowing process by Nikki Mills et al (2), but the realization of the approach in common practice is more than rare and reserved for scientific centers. Material: we report first three cases of mother-child-combined MRI for central nervous system examination in children under 3 years of age (26, 26 and 29 months) without sedation or anesthesia in general radiology unit.

We have performed brain MRI examinations in parent-childcombined side-by-side position. For the brain MRI we positioned the child head-first into the scanner in supine position; the parent was positioned in the decubitus position side-by-side their child, head first at the child`s chest level. The parent was positioned at the closest proximity to the child keeping the eye and voice contact, but out of the field of the scan. The ordinary head coil was used for the examination. For the whole spine MRI, we have used the parent-child-combined headto-head positioning described by Safwat Aly and Lars Grosse-Wortmann (1). Head-to-head positioning was useful to avoid an interference of two bodies in the field of view. This was important, as we have used routine table coils for the spine imaging. Part of the head and arm of the parent have fallen into the field of view only in one of three localizers. Results: In our experience, application of parent-child-combined method is feasible in general radiology departments without full time specialization in pediatric radiology. Conclusions: We confirm the success of the parent-child-combined positioning in MRI bore for brain and spine MRI with our experience of three patients under 3 years of age. Application of parent-child-combined positioning in different MRI investigations can reduce the need of general anesthesia in children. Purpose: Hearing loss (HL) is a common birth defect in developed countries and can be congenital, due to genetic factors or acquired due to fetal or perinatal event. Approximately 30% of cases with genetic HL are considered to be syndromic with additional abnormalities. In most of these cases, middle and inner ear malformations are found and several of them are quite characteristic in a manner that could lead to the diagnosis. In this presentation, we illustrate the spectrum of middle and inner ear abnormalities, detected on imaging (CT and MRI), in children with syndromic HL. Material and Methods: We retrospectively reviewed all CT and MRI imaging of internal auditory canals performed in pediatric population in our hospital for evaluation of congenital hearing loss. All cases proved to be related with a clinical syndrome were evaluated and imaging findings from middle and inner ear were recorded. Results: Different well recognizable clinical entities such as CHARGE association, Waardenburg syndrome, Pendred syndrome and 22q11 microdeletion are characterized by consistent imaging findings of middle and inner ear. These imaging findings alone or in combination with the other systemic or skeletal features of the syndrome can strongly suggest the diagnosis. Conclusion: CT and/or MRI imaging of middle and inner ear can contribute to the early diagnosis of a syndromic association, improving patient care and allowing appropriate genetic counseling.

Lelong P, Peslerbe S, De Carli E, Pellier I, Aube C, Leiber LM 1. CHU, Angers, FranceOptic pathway gliomas (OPGs) are rare neoplasms, but they are the most common type of childhood tumour involving the optic pathway. Most OPGs are WHO grade I gliomas, but despite a benign histology, their clinical and radiological progression is highly unpredictable and their treatment is challenging. The role of imaging in patients with OPGs is to ensure a positive diagnosis while excluding differentials, to evaluate local or regional Considering the increasing use of this modality in pediatric focal liver lesions assessment it is imperative to analyze the features of rare lesions in CEUS. The aim of this case report is therefore to present the CEUS and magnetic resonance (MRI) imaging features of FL-HCC. Material and methods: A 14-year-old girl with no significant clinical symptoms and only mildly elevated liver enzyme levels (GGTP, AST and ALT) was referred to our center for further evaluation of an incidentally identified focal liver lesion. She underwent abdominal ultrasound examination, CEUS of the liver focal lesion and contrast-enhanced MRI. Results: Abdominal ultrasound examination revealed a round, ill-defined heterogenous iso-to hypoechoic solid lesion, with calcifications and fluid areas, located in the 4th segment of the liver. Color Doppler demonstrated an internal vascularity with a large, central artery. After contrast administration heterogenous arterial hyperenhancement was observed, with hypo-/ nonenhancing areas. In the portal venous and the late phases the pathological mass become isoechogenic to normal liver parenchyma, with several unenhanced areas. Rapid wash-out was not observed in the CEUS examination. Pre-contrast T1-and T2-weighted MRI showed a heterogenous, irregular liver mass, that enhanced heterogeneously after contrast administration, with no restricted diffusion on DWI. The imaging features were not specific, and the patient underwent core needle biopsy, which confirmed FL-HCC. Conclusion: CEUS is a valuable diagnostic modality, which allows to evaluate lesions real-time contrast enhancement in all vascular phases and may help differentiate between benign and malignant lesions. We describe the imaging features of FL-HCC in an adolescent girl and highlight its differences from focal nodule hyperplasia (FNH), a common benign lesion in the pediatric population. The differentiation between those lesions is crucial, especially as FL-HCC may have nonspecific radiographic features without typical enhancement characteristics of a malignant tumor and shares some similarities with FNH. Results: Our first case is of a 10-year-old girl that presented to the emergency room with nonspecific symptoms (abdominal pain and distension, constipation, loss of appetite) and on physical examination a palpable mass was noted in the right iliac fossa. Our second case is of a 16-year-old boy that presented to the emergency room also with nonspecific symptoms (abdominal pain for a few months with worsening over the previous week) and on physical examination an epigastric mass and hepatomegaly were identified. In both cases the initial investigation was performed with abdominal and pelvic ultrasound, which was suggestive of Burkitt lymphoma, followed by computed tomography (CT) to assess disease multifocality. In the abdomen the ileocecal region is the most commonly involved site of Burkitt lymphoma, as was seen in our first case, while the second case illustrates the involvement of the stomach. In both cases the disease was bulky with multiple organ involvement. In the first case we detected renal, gonadal, pleural and central nervous system (cerebrospinal fluid) involvement and in the second case hepatic, lymphatic and mediastinal involvement was identified. Imaging aids in staging and allows for the identification of the most accessible location for histological or cytological confirmation. In the first case the diagnosis was determined by pleural fluid cytology and in the second case by endoscopic gastric biopsies. Imaging also assists in determining response to treatment either by ultrasound, CT or positron emission tomography (PET). Conclusions: Awareness and recognition of the imaging findings of the highly aggressive Burkitt lymphoma allows for a prompt diagnosis and management of these patients. Purpose: Congenital Mesoblastic Nephroma (CMN) is a rare paediatric renal tumour of low malignant potential, with an incidence of 8 per million [i] . It is however the commonest renal tumour presenting in the neonatal period, often as a palpable abdominal mass. Nephrectomy is the treatment of choice, with a reported long-term survival of over 98% [ii] . Disease recurrence and metastases are extremely rare [iii] and to our knowledge the imaging features of disease recurrence have not been described before. We aim to present the imaging findings of CMN at diagnosis on ultrasound, CT and MR imaging, as well as the imaging characteristics of disease recurrence. Material and Methods: A single-center retrospective review of histologically confirmed CMNs over a twenty year period was performed. Patients' imaging was reviewed in conjunction with the clinical and pathology notes. Results: 30 patients with CMN were identified. There were 16 female and 14 male patients, ranging from 4 days to 17 months old at time of histological diagnosis (median age 41 days). Complete imaging and clinical data was available for 23 patients; four patients had cross-sectional imaging performed exclusively at an outside institution. Two patients demonstrated local disease recurrence, both within six months of nephrectomy. There were no instances of metastatic disease. Ultrasound, CT and MR imaging at time of diagnosis demonstrates a range of heterogenous appearances of a predominantly solid tumour. Areas of cystic change and necrosis, internal haemorrhage, and variable enhancement can be seen. Recurrent disease is identified as a large mixed solid-cystic mass extensively within the abdomen, with a predominant fluid-filled component and enhancing, diffusion-restricting solid component. Both cases of recurrence were successfully treated with a combination of chemo-radiotherapy and surgery. Conclusions: CMN is a rare paediatric renal tumour of low malignant potential. Complete surgical resection portends extremely good outcomes, though disease recurrence can occur. Our center's experience has highlighted the common cross-sectional imaging findings of CMNs at diagnosis and also importantly, of the rare instances of intra-abdominal disease recurrence.

Beverley Newman 1 1. Stanford University, Stanford, United States Purpose: Pleuropulmonary blastoma is a rare embryonal mesenchymal neoplasm, the most common primary pulmonary lung malignancy in children. PPB is often associated with a hereditary familial tumor predisposition; a Dicer 1 gene mutation is present in~75% of cases. The purpose of this educational poster is to illustrate the imaging spectrum of PPB in children and highlight other neoplasms that can occur in conjunction with a Dicer 1 mutation. Materials, Methods & Results: The cases shown will include type 1 PPB in infancy with one or more small cystic lung lesions, larger multicystic lesion/s (difficult to distinguish from congenital cystic lung malformation), pneumothorax, large cystic/solid (type2) or solid (type 3) mass in young to older children. Other Dicer1 associated neoplastic masses, predominantly those of the kidney and endocrine organs, especially thyroid and ovary, will also be illustrated. Conclusions: It is important to understand and recognize the spectrum of imaging appearances of PPB in children. PPB is the most common and concerning lesion associated with a Dicer-1 gene mutation. Timely removal or surveillance of suspicious cystic lung lesions in young children is important in prognosis. Presentation of the associated lesions in a child should raise suspicion of an underlying Dicer1 gene mutation. This recognition prompts early diagnosis, appropriate evaluation and management of these children. Introduction and objectives: Pediatric hematopoietic stem cell transplantation (HSCT) can be used as treatment for both malignant and non-malignant diseases. Children who undergo hematopoietic stem cell transplantation are at risk of developing specific complications that are linked to the timeline of transplantation, as well as to the relationship between the underlying diagnoses, severe immune deficiency, cytoreductive regimen and graft-versus-host reactions. Understanding the complex interplay between the immune status, therapeutic regimen and disease characteristics allows increased diagnostic accuracy. Methods: This study uses illustrative cases from the Pediatric Radiology group of a Brazilian quaternary hospital, with different radiological methods that demonstrate manifestations of thoracic and abdominal complications after hematopoietic stem cell transplantation in children, such as sinusoidal obstruction syndrome (SOS), also called hepatic venoocclusive disease (VOD), pseudomembranous colitis, neutropenic colitis, hepatic and splenic microabscesses, hemorrhagic cystitis, angioinvasive aspergillosis, alveolar hemorrhage, pulmonary edema, among others. Discussion: The HSCT therapy is intended to completely or partially replace the recipient's existing diseased hematopoietic system. This process requires ablation of the recipient's bone marrow and tumor cells, which usually entails use of high-dose chemotherapy and/ or total body irradiation. After this conditioning regimen, stem cells are transfused to restore and repopulate the patient's marrow. Complications can manifest in almost all organ systems and follow a predictable temporal sequence that mirrors the periods of immunosuppression and recovery following transplantation. In general, there are three phases following transplantation: pre-engraftment phase (0-30 days post-transplant), early posttransplantation phase (30-100 days post-transplant), and late posttransplant phase (>100 days post-transplant).

Conclusion: Systemic stem cell therapy can evolve with several complications in multiple organ systems primarily dependent on the immune status and type of HSCT. The role of imaging is mainly to detect and narrow the differential diagnosis of such complications. Radiologists must be aware of these complications and their relation to the underlying immune-physiological status, in order to be able to promptly make the accurate diagnosis on imaging methods.Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.