Imaging of cerebrovascular reserve and oxygenation in Moyamoya disease

Abstract

This study aimed to determine whether measurements of cerebrovascular reserve and oxygenation, assessed with spin relaxation rate R2′, yield similar information about pathology in pre-operative Moyamoya disease patients, and to assess whether R2′ is a better measure of oxygenation than other proposed markers, such as R2* and R2. Twenty-five preoperative Moyamoya disease patients were scanned at 3.0T with acetazolamide challenge. Cerebral blood flow mapping with multi-delay arterial spin labeling, and R2*, R2, and R2′ mapping with Gradient-Echo Sampling of Free Induction Decay and Echo were performed. No baseline cerebral blood flow difference was found between angiographically abnormal and normal regions (49±12 vs. 48±11 mL/100 g/min, p=0.44). However, baseline R2′ differed between these regions (3.2±0.7 vs. 2.9±0.6 s-1, p<0.001), indicating reduced oxygenation in abnormal regions. Cerebrovascular reserve was lower in angiographically abnormal regions (21±38 vs. 41±26%, p=0.001). All regions showed trend toward significantly improved oxygenation post-acetazolamide. Regions with poorer cerebrovascular reserve had lower baseline oxygenation (Kendall’s τ=-0.24, p=0.003). A number of angiographically abnormal regions demonstrated preserved cerebrovascular reserve, likely due to the presence of collaterals. Finally, of the concurrently measured relaxation rates, R2′ was superior for oxygenation assessment.