Abstract WMP53: Revascularization Improves Cerebrovascular Reserve In Moyamoya Patients

Introduction: Cerebrovascular reserve (CVR) reflects the change in cerebral blood flow (CBF) in response to a vasoactive stimulus and can be measured using a brain stress test whereby CBF is augmented using vasodilators. Studies have demonstrated that impaired CVR was associated with a higher risk of acute stroke and that bypass can reduce the risk of strokes. Arterial spin labeling is a quantitative MRI technique that enables non-invasive CBF and CVR measurement. Studies have shown the effectiveness of ASL in identifying CVR impairment in Moyamoya patients. Here, we compare the CBF and CVR of Moyamoya patients before and after bypass using single and multiple delay ASL techniques. Methods: MRI data were acquired from 24 Moyamoya patients (16-54 years, 3 males) using a 3T MRI system. All patients had unilateral or bilateral vessel occlusion at ACA, MCA and/or PCA. The scanning parameters of the single post-labeling delay pseudo-continuous ASL (single-PLD PCASL), delay pseudo-continuous ASL (multi-PLD PCASL, 5 PLDs) 2. ASL data were acquired simultaneously at baseline and 15 minutes after the injection of the vasodilator acetazolamide (15 mg/kg with a maximum 1 g). CBF was computed using the general kinetic model. CVR was computed as the percentage of CBF change compared with baseline CBF. Flow territories (right and left ACA, MCA, and PCA) were defined based on the Harvard-Oxford cortical and subcortical structural atlases. Mean CVR within the territories affected by occlusion and normal territories was computed for each subject. T-tests were performed to compare the mean CVR between the affected and unaffected territories. Results: For this cohort, our quantitative analysis revealed that CVR of the affected regions increased significantly by 12% and 21% measured by single and multiple delay PCASL respectively, implying improved CBF and lower risk for strokes. Discussion: ASL was effective to detect improved CBF and CVR in Moyamoya patients after bypass surgeries.