Quantitative Cerebrovascular Reserve Measured by Acetazolamide-Challenged Dynamic CT Perfusion in Ischemic Adult Moyamoya Disease : Initial Experience with Angiographic Correlation

Abstract

CT perfusion is a much more readily accessible imaging method to assess cerebral hemodynamic status than single-photon emission CT. We prospectively assessed quantitative cerebrovascular reserve by using acetazolamide (ACZ)-challenged CT perfusion for evaluating hemodynamic impairment in ischemic adult Moyamoya disease and compared it with angiographic findings. Sixteen adult patients with ischemic Moyamoya disease and 12 age-matched normal control subjects underwent both ACZ-challenged CT perfusion and digital subtraction angiography. Normalized baseline hemodynamic parameters and their percent changes (PCs) were calculated in 56 hemispheres. We classified the degrees of distal carotid artery stenosis according to modified Suzuki stage and determined the presence of basal Moyamoya vessels (BMVs). The values of normalized parameters and their PCs were compared with angiographic findings. Normalized baseline mean transit time (MTT) and PC of normalized cerebral blood flow (CBF) were significantly correlated with angiographic stages in all of the vascular territories; however, the correlation coefficient of the normalized baseline MTT was lower than that of the PC of CBF. In the external borderzone and the middle cerebral arterial territory, the hemispheres with extensive BMVs exhibited significantly lower PC values of CBF and significantly higher normalized baseline MTT values than those in hemispheres with diminished BMVs and in normal control subjects. Among the hemodynamic parameters measured by ACZ-challenged CT perfusion, the PC of CBF correlated highly significantly with angiographic stage; however, the normalized baseline CT perfusion parameters showed weak or no significant correlation.