key: cord-0978365-mzue2sjk
authors: Guggenberger, Konstanze V.; Bley, Thorsten A.; Vogt, Marius L.; Urbach, Horst; Meckel, Stephan
title: High-Resolution Black Blood Vessel Wall Imaging in COVID-19 Encephalopathy—Is it Really Endotheliitis?
date: 2021-10-28
journal: Clin Neuroradiol
DOI: 10.1007/s00062-021-01109-y
sha: 7148e15e9f436761cca81caefc9962e303719cc6
doc_id: 978365
cord_uid: mzue2sjk

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scale, or the presence of microbleeds on susceptibilityweighted images. Most importantly, neither histopathological correlation from any of their patients nor a control group of age-matched patients without COVID-19 encephalopathy was presented. Given these limitations, such conclusion cannot be drawn from their descriptive study findings.

To account for their study findings, intracranial vasa vasorum, developing with advancing age, typically causing concentric mural contrast enhancement and vessel wall thickening in vessel wall imaging using black-blood MRI [2] , need to be considered. This type of vessel wall enhancement is frequently found on MRI vessel wall images in older subjects along the proximal intracranial vessel segments [3] after the vessels' dural crossing and may be easily mistaken for inflammatory changes, such as vasculitis. In our recently published study, we analyzed 43 older (mean age 71 years, SD 10 years) subjects without any clinical or laboratory signs of vasculitis and found concentric vessel wall enhancement of the proximal intradural vertebral artery in 39 patients (91%) [4] . Mean longitudinal extension of vessel wall enhancement after dural entry was 13 mm (range 0-52 mm) in the vertebral artery (right vertebral artery mean 12 mm, range 0-34 mm, left vertebral artery 14 mm, range 0-52 mm).

The reported images showing vessel wall enhancement of the proximal vertebral arteries (left vertebral artery in Fig. 1d and Fig 2a- c; bilateral vertebral arteries in Fig. 3d ) of the addressed study [1] resemble the appearance of high-resolution vessel wall images from our non-vasculitic cohort (Fig. 2a-c, Fig. 3b in [4] ): concentric vessel wall enhancement and slight vessel wall thickening of the nonstenotic vertebral artery in its proximal intradural course. This finding most likely represents vasa vasorum related vessel wall enhancement and should not be misinterpreted as inflammatory affection. Previous histopathologic and imaging studies have revealed results that support the presence of vasa vasorum causing these vessel wall imaging findings [3, [5] [6] [7] . We do not intend to refute the results of the addressed study but rather draw attention to the fact that vasa vasorum may constitute a potential confounder in diagnosing endotheliitis or intracranial vasculitis. Vessel wall enhancement in the proximal intradural vessel segments, in particular affecting the proximal vertebral arteries, is a common finding in non-vasculitic older patients without any pathologic significance. Supportive of this interpretation is the fact that COVID-19 related cerebral endotheliitis was hitherto described in small intracerebral vessels in a histopathological study [8] . Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4. 0/.

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Intracerebral endotheliitis and microbleeds are neuropathological features of COVID-19