Characterization of cerebrovascular reactivity in aging, Alzheimer’s disease, and vascular dementia using multi-echo, multi-contrast MRI

Motivation: Cerebrovascular reactivity (CVR) shows promise as an imaging biomarker of changes in vascular integrity. Microvascular-weighted images may be more specific to disease-related pathology, but these acquisitions suffer from lower contrast-to-noise ratio. Goal(s): We aim to evaluate CVR in Alzheimer's disease (AD) and vascular dementia (VaD) using a combined spin- and gradient-echo (SAGE) acquisition. Approach: SAGE-fMRI, demographic, and cognitive testing data were collected. Total and microvascular-weighted SAGE-fMRI CVR maps were generated. Regional group differences were assessed. Results: Microvascular-weighted CVR revealed multi-regional deficits for VaD compared to healthy aging and AD. Positive correlations of CVR with cognitive testing and negative correlations with age were observed. Impact: Complementary assessments of CVR on total and microvascular scales may comprehensively inform on differences in vascular integrity between populations. The microvascular-weighted analysis was sensitive to changes in CVR between groups and may be specific to dementia-related pathology in the microvasculature.