Which CT Perfusion Parameter Best Reflects Cerebrovascular Reserve?: Correlation of Acetazolamide-Challenged CT Perfusion with Single-Photon Emission CT in Moyamoya Patients

N.-J Rim,Y.S Shin,H.S Kim,S.Y Kim

doi:10.3174/ajnr.a1229

Abstract

CT perfusion (CTP) is a 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 percentage changes were calculated in 152 regions of interest (ROIs). On qualitative SPECT analysis, each ROI was classified in either the "impaired CVR" or "normal CVR" group. Quantitative CVR was calculated by using normalized SPECT values before and after acetazolamide administration. Baseline CTP parameters and their percentage 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. The percentage change of cerebral blood flow (pcCBF) was correlated most significantly with quantitative CVR (r = 0.89; P < .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 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 correlated strongly with quantitative CVR; therefore, CTP evaluation for CVR in Moyamoya patients requires normalization and acetazolamide challenge.

Highlights

AND PURPOSE: CT perfusion (CTP) is a more readily accessible method for evaluation of cerebral perfusion than single-photon emission CT (SPECT)
In the comparison of CTP parameters with qualitative cerebrovascular reserve (CVR), the mean values of all of the baseline CTP parameters and their percent change (PC) were significantly different in external borderzone (EBZ) between the normal and impaired CVR groups
In this study, we found that the percentage change of cerebral blood flow (pcCBF) among CTP parameters correlated significantly with quantitative CVR obtained by SPECT, indicating that pcCBF is a reliable parameter of vascular reserve in patients with Moyamoya disease in spite of the limitation of the deconvolution algorithm in Moyamoya disease

Summary

Methods

Normalized baseline CTP parameters and their percentage changes were calculated in 152 regions of interest (ROIs). Quantitative CVR was calculated by using normalized SPECT values before and after acetazolamide administration. Baseline CTP parameters and their percentage 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 inclusion criteria of patients in this study were as follows: underwent both ACZ-CTP and SPECT, bilateral Moyamoya disease diagnosed by DSA as proposed by Suzuki and Kodama,[10] normal finding of posterior circulation on DSA, no evidence of hemorrhage on CT scans, and no notable renal insufficiency or allergy to the contrast agent. Our institutional review board approved this study, and written informed consent was obtained from every participant in accordance with the guidelines of the institutional review board at our institution

Results

Discussion

Conclusion