Spatial Coefficient of Variation (sCOV) From ASL MRI Reveals Global Cerebrovascular Dysfunction in Long COVID.

Long COVID participants showed significantly higher global gray matter spatial coefficient of variation (sCOV) compared with controls.

• Study examined 186 adults from an Argentine cohort (145 long COVID and 41 controls), approximately 2 years postinfection.
• Global gray matter sCOV was significantly higher in long COVID vs. controls (p = 0.02) after FDR correction.
• Group comparisons were performed using multivariate models adjusted for age, sex, and white matter hyperintensity (WMH) volume.
• Three-dimensional pulsed ASL data were processed with ExploreASL to quantify CBF and sCOV in gray matter and lobar regions.

Regional sCOV showed consistent trends of elevation across multiple lobar regions in long COVID participants.

• Frontal lobe sCOV trends: left p = 0.05, right p = 0.07.
• Temporal lobe sCOV trends: left p = 0.05, right p = 0.08.
• Parietal lobe sCOV trends: left p = 0.07, right p = 0.06.
• Occipital lobe sCOV trends: left p = 0.08, right p = 0.05.
• Insular lobe sCOV: left p = 0.01, right p = 0.15; all values reported after FDR correction.

Mean global, lobar, and regional gray matter cerebral blood flow (CBF) did not differ significantly between long COVID and control groups.

• Despite elevated sCOV, no significant differences in CBF were observed at global, lobar, or regional gray matter levels.
• This indicates cerebrovascular dysfunction in long COVID exists in the absence of frank perfusion deficits.
• Previous studies have reported hypoperfusion in long COVID patients, but this study did not replicate those findings.

White matter hyperintensity (WMH) volumes did not differ significantly between long COVID and control groups.

• WMH volume was included as a covariate in multivariate models.
• The elevated sCOV in long COVID was not associated with white matter hyperintensities.
• This suggests the cerebrovascular dysfunction reflected by sCOV is independent of macrostructural white matter damage.

Increased sCOV was interpreted as reflecting delayed arterial transit time and reduced vascular efficiency, indicating widespread cerebrovascular dysfunction in long COVID.

• sCOV has been previously used as a proxy of arterial transit time, providing a noninvasive marker of global cerebrovascular function.
• Delayed arterial transit time can affect standard ASL quantification of CBF, and few prior long COVID studies have accounted for this.
• Vascular dysregulation, endothelial dysfunction, and microvascular injury have been proposed as potential contributors to long COVID neurological symptoms.
• The authors conclude that sCOV supports identification of global vascular impairment approximately 2 years postinfection.

sCOV was supported as a sensitive, noninvasive biomarker of cerebrovascular health in long COVID.

• sCOV detected cerebrovascular differences that were not apparent from CBF measurements alone.
• The metric is derived from standard ASL MRI data, making it a noninvasive approach.
• The authors propose sCOV can reveal global vascular impairment even in the absence of perfusion deficits or white matter changes.