A Comparative Olfactory MRI, DTI and fMRI Study of COVID-19 Related Anosmia and Post Viral Olfactory Dysfunction


YILDIRIM D. , Kandemirli S. G. , Sanli D. E. T. , Akinci O., Altundag A.

ACADEMIC RADIOLOGY, vol.29, no.1, pp.31-41, 2022 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 29 Issue: 1
  • Publication Date: 2022
  • Doi Number: 10.1016/j.acra.2021.10.019
  • Title of Journal : ACADEMIC RADIOLOGY
  • Page Numbers: pp.31-41
  • Keywords: olfactory bulb MRI, COVID, infection, anosmia, smell, BULB VOLUME, DISORDERS, DIAGNOSIS, STIMULI

Abstract

Rationale and Objective: To evaluate how COVID-19 anosmia imaging findings resembled and differed from postinfectious olfactory Material and Methods: A total of 31 patients presenting with persistent COVID-19 related OD and 97 patients with post-infectious OD were included. Olfactory bulb MRI, DTI and olfactory fMRI findings in both groups were retrospectively assessed. Results: All COVID-19 related OD cases were anosmic, 18.6% of post-infectious OD patients were hyposmic and remaining 81.4% were anosmic. Mean interval between onset of OD and imaging was 1.5 months for COVID-19 related OD and 6 months for post-infectious OD. Olfactory bulb volumes were significantly higher in COVID-19 related OD than post-infectious OD. Deformed bulb morphology and increased olfactory bulb signal intensity was seen in 58.1% and 51.6% with COVID-19 related OD; and 63.9% - 46.4% with post-infectious OD; without significant difference. Significantly higher rate of olfactory nerve clumping and higher QA values at orbitofrontal and entorhinal regions were observed in COVID-19 related OD than post-infectious OD. Absence of orbitofrontal and entorhinal activity showed no statistically significant difference between COVID-19 related OD and postinfectious OD, however trigeminosensory activity was more robust in COVID-19 related OD cases. Conclusion: Olfactory bulb damage may play a central role in persistent COVID-19 related anosmia. Though there is decreased olfactory bulb volume and decreased white matter tract integrity of olfactory regions in COVID-19 related anosmia, this is not as pronounced as in other post-infectious OD. Trigeminosensory activity was more robust in COVID-19 related OD. These findings may reflect better preserved central olfactory system in COVID-19 related OD compared to COVID-19 related OD. (c) 2021 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.