Evaluation of multi-delay arterial spin labeling MRI-based measures of cerebral blood flow in a PET/MRI study of aging

Motivation: Arterial spin labeling (ASL) MRI with a single post-labeling delay may not be appropriate for quantifying cerebral blood flow (CBF) in older participants or individuals with Alzheimer’s disease (AD). Goal(s): To evaluate reliability of multi-delay versus single-delay ASL and their associations with [15O]water positron emission tomography (PET) using simultaneous PET/MRI in older adults. Approach: We investigated 4-week test-retest reliability using intra-class correlation (ICC) and assessed Spearman’s correlations between ASL and PET in young and older controls (n=12) and AD patients (n=3). Results: ICC values were similar between ASL approaches but exhibited regional differences. Multi-delay ASL-based CBF was correlated with PET in more regions-of-interest. Impact: Multi-delay arterial spin labeling MRI provides CBF measures with good intermediate-term reliability that are strongly correlated with gold-standard [15O]water PET when studying older adults and AD patients.