key: cord-0823660-r5aojrrr
authors: Robinson, G.R.E.; Edey, A.; Hare, S.; Holloway, B.; Jacob, J.; Johnstone, A.; McStay, R.; Nair, A.; Rodrigues, J.
title: Re: Indiscriminate use of CT chest imaging during the COVID-19 pandemic. A reply
date: 2022-01-31
journal: Clin Radiol
DOI: 10.1016/j.crad.2022.01.042
sha: 31dc8c45c5b9ad98858ff404c092c0cd25030771
doc_id: 823660
cord_uid: r5aojrrr

nan

Re: Indiscriminate use of CT chest imaging during the COVID-19 pandemic. A reply Sir-We read with interest the comments by Professor Khashu and colleagues regarding the potential indiscriminate and heterogeneous use of computed tomography (CT) chest imaging during the COVID-19 pandemic. In the early part of 2020, two of the major considerations posed to the British Society of Thoracic Imaging (BSTI) were: "when should CT be used in patients who may have or have proven COVID-19?" and "should CT be used for diagnosis in COVID-19".

These hypothetical scenarios were discussed by BSTI at the beginning of the pandemic [1] . It is important to remember this was on the backdrop of not just availability but also timeliness of reverse transcriptase polymerase chain reaction (PCR) testing, (subsequently through 2021 we have seen the massive impact of widespread PCR testing and lateral flow testing).

In those initial weeks of the pandemic, there was pressure to consider using CT as a surrogate for a PCR, allowing patients to be appropriately managed in "COVID-19" versus "non-COVID-19" hospital areas and to advise on periods of isolation for those not needing admission. We talked to our colleagues in Italy, who were a few months ahead of the UK. There CT was used relatively widely, but, of course, healthcare systems are different (the UK has less CT capacity per head of population than many European neighbours) and we learn from each other's experiences.

As highlighted in the letter by Professor Khashu, we believed widespread use of CT

was not the answer to the questions posed principally because: (a) a normal CT J o u r n a l P r e -p r o o f does not exclude COVID-19 infection and cannot be used to reliably manage "isolation" versus "non-isolation," and (b) there is a fundamental lack of specificity (areas of ground-glass opacity at the bases do not necessarily equate to COVID-19).

Subsequent systematic reviews have since further supported the adequate sensitivity, but moderate specificity, at best, of chest CT for COVID-19 [2] Additionally, we felt there was a risk of the scanners themselves acting as a disease vector if used indiscriminately, to both subsequent patients, but also to the radiography staff. By a similar token, there was also potential risk to porters, other staff, and patients of transferring "hundreds" around the hospital and through radiology departments. For these reasons and with a national multidisciplinary discussion, the BSTI/National Health Service England (NHSE) radiology decision tool was published [3] . This attempted to place CT in a pragmatic position for the UK system, largely for patients who were seriously ill. At that time (and again largely due to low PCR availability and result turnaround), we proposed that CT may have a role in the very specific situation of high clinical suspicion but repeated negative PCR [4] .

Through subsequent waves, the BSTI/NHSE advice has not significantly changed:

we should use CT as part of "routine clinical care", that is, for patients who have been admitted with COVID-19 and who are not taking an expected clinical course.

For these patients, we would advocate unenhanced CT of the thorax. For more seriously ill patients, especially those with "disproportionate hypoxia" or a "sudden clinical deterioration" a CT pulmonary angiogram may be considered.

In summary, we agree with many of the points raised by Professor Khashu and colleagues. The indiscriminate use of CT in COVID-19 in some areas did not meet

A British Society of Thoracic Imaging statement: considerations in designing local imaging diagnostic algorithms for the COVID-19 pandemic

Thoracic imaging tests for the diagnosis of COVID-19. Cochrane Database of Systematic Reviews 2021

Radiology decision tool for suspected COVID-19

Managing high clinical suspicion COVID-19

inpatients with negative RT-PCR: a pragmatic and limited role for thoracic CT