Olfactory bulb volume and cerebral connectivity of post-viral (COVID-19) smell loss patients: preliminary results of APOLLO trial

Motivation: Post-infectious olfactory disfunction (PIOD) came into light after COVID-19 pandemic. Many survivors have either completely or partially lost their smell sense. We recently completed APOLLO trial, which explores the effectiveness of vitamin-A nasal drops in regaining olfaction for PIOD patients Goal(s): To investigate into the primary outcome of APOLLO trial: olfactory bulb volume (OBV) and two secondary outcomes: structural and functional cerebral connectivity. Approach: We investigated the inter-observer agreement for manual OB segmentation; also, explored difference in connectivity between anosmic and hyposmic brains. Results: The inter-observer agreement was satisfactory; no differences were found in the cerebral connectivity of anosmic and hyposmic cohort. Impact: Interim analysis results on baseline scans of APOLLO trial's olfactory disorder patients indicate their suitability to be extended for entire cohort. This study establishes the basis for currently ongoing APOLLO analysis.