Comparison of Acetazolamide-Challenged CT Perfusion with Acetazolamide-Challenged SPECT in Moyamoya Patients
CT perfusion (CTP) is more readily accessible method for evaluation of cerebral perfusion than single photon emission CT (SPECT). We assessed whether there is any resting or drug-challenged CTP parameter correlating with cerebrovascular reserve (CVR) obtained by SPECT in moyamoya patients. Normalized baseline CTP parameters and their percent changes were calculated in 152 regions of interest (ROIs). On qualitative SPECT analysis, each ROI was classified as “impaired CVR” and “normal CVR” groups. Quantitative CVR was calculated with using normalized SPECT values before and after acetazolamide administration. Baseline CTP parameters and their percent changes were compared with qualitative and quantitative CVRs. Receiver operating characteristic (ROC) curve analysis defined the threshold values of CTP parameters that best predict impaired qualitative CVR. The mean values of CTP parameters were significantly different between normal and impaired CVR groups. Percent change of cerebral blood flow (pcCBF) was most significantly correlated with quantitative CVR (r = 0.89, P < 0.05). The correlation coefficients between the baseline CTP parameters and quantitative CVR were poor or not significant. The ROC-derived threshold values of pcCBF and mean transit time (MTT) determined impaired CVR with a sensitivity of 94.4 and 85.2; specificity of 93.2 and 65.9; positive predictive value of 97.1 and 86.0; and negative predictive value of 87.2 and 64.4 respectively. Baseline CTP parameters are not reliable for predicting impaired CVR. However, pcCBF strong correlated with quantitative CVR, therefore, CTP evaluation for CVR in moyamoya patients requires normalization and ACZ challenge.
CT perfusion, Cerebrovascular reserve, Moyamoya disease, SPECT, Acetazolamide
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