Abstract Details

Here we report diffusion magnetic resonance imaging (3 T Siemens MRI) findings from 40 patients (mean age: 43.7, 68% female) who self-isolated after testing positive for COVID (COV+), and 14 COVID negative (COV-) subjects (mean age: 43, 64% female) who had flu-like symptoms. This is part of the Canadian-based NeuroCOVID-19 study.

Fractional anisotropy (FA), mean diffusivity (MD), mode of anisotropy (MO), free water fraction (F), tissue-specific FA (FAt) and tissue-specific MD (MDt) were obtained using data with b=700 and 1400 (DIPY free-water model). Regions of interest in the grey matter and white matter were delineated using FreeSurfer. Differences between groups were assessed using an analysis of variance (ANOVA), the Kruskal-Wallis Test and the Mann-Whitney Test, corrected for false-discovery rate of 0.05. Effect size (Cohen’s d) was also computed (d>0.45 deemed large effect).

In the COV+ group, all three tests revealed decreased FA and FAt in the insula, and increased MD in the parstriangularis cortex. Increased FA and FAt in the cuneus (along with decreased MD) was also found. MD was reduced in COV+ in the temporal and supramarginal areas. MO was lower in COV+ in the insula and amygdala regions. 

In patients, higher MD with lower FA and MO suggest increased extracellular fluids, while lower MD with decreased FA and MO may suggest necrotic debris built up following inflammation. The cuneus and insula are involved in visual and taste processing, respectively. This study highlights the need to study neurological effects of COVID-19.