Cerebrovascular Reactivity Measured with ASL Perfusion MRI, Ivy Sign, and Regional Tissue Vascularization in Moyamoya

Background Arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) may be used to determine brain regions at risk for ischemia in patients with moyamoya vasculopathy and to identify patients who may benefit from surgical revascularization. We aimed to investigate whether 1) the severity of moyamoya is related to the presence of leptomeningeal collaterals and cerebrovascular reactivity (CVR), 2) the presence of collaterals and ivy sign reflects disturbed CVR, and 3) arterial transit artefacts (ATAs) and ivy sign reflect the presence of collaterals. Methods We determined severity of moyamoya on digital subtraction angiography (DSA) according to the modified Suzuki classification in 20 brain regions and scored regional tissue revascularization using a 4-point scale. Regional CVR and ATAs were assessed on ASL perfusion MRI, ivy sign on fluid attenuation inversion recovery MRI. Results In 11 patients (median age 36 years; 91% female), we studied 203 regions. ATAs were associated with the presence of collaterals on DSA ( P Conclusions ATAs were associated with the presence of collaterals on DSA. Although DSA vascularization scores correlated with CVR, 10% of regions with good vascularization on DSA had absent CVR or steal on ASL-MRI. DSA and ivy sign did not provide adequate information on the hemodynamic status of brain tissue in patients with moyamoya vasculopathy.