Fig. 2: Spatial distribution and direction of microstructural changes after COVID-19.

A The standardized regression coefficients of the factors V-extra and V-CSF were extracted from two-tailed linear regression models yielded by voxel-wise comparisons between all participants after COVID-19 infection (i.e., combined PCC and UPC group) and controls without a history of COVID-19 (HNC; with nuisance covariates age and sex), and were superimposed onto a T1w MRI template. Color-coding indicates the coefficient values as a measure of effect size of the factor COVID-19 (hot colors: positive effects vs. cold colors: negative effects). Results of voxel-based two-tailed linear regression models of V-extra after threshold-free cluster enhancement and FWE-correction (top row), and standardized regression coefficients derived from the same model (bottom row) between different groups: B Post-COVID-Condition (PCC) vs. Healthy Non-COVID controls (HNC), C. Unimpaired-Post-COVID participants (UPC) vs. Healthy Non-COVID controls (HNC), and (D). Post-COVID-Condition (PCC) vs. Unimpaired-Post-COVID (UPC). Voxels with significantly different V-extra were indicated by hot shading and superimposed onto a T1w MRI template (top rows). Two-tailed P values were corrected for multiple comparisons across voxels using the family-wise error rate (FWE), with age and sex as nuisance covariates. Color-coding indicates the coefficient values as a measure of effect size of the factor COVID-19 (hot colors: positive effects vs. cold colors: negative effects; bottom rows). Radiological orientation: left side of the image corresponds to the patient’s right; numbers denote the axial (z) position in millimeters. The statistic was based on 46 HNC, 38 UPC, and 89 PCC cases.