title: Which CT perfusion parameter best reflects cerebrovascular reserve?: correlation of acetazolamide-challenged CT perfusion with single-photon emission CT in Moyamoya patients.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Diagnostic Radiology, Ajou University School of Medicine, Gyeonggi-do, Korea.
authors.forename: N-J
authors.initials: NJ
authors.lastname: Rim
authors.forename: H S
authors.initials: HS
authors.lastname: Kim
authors.forename: Y S
authors.initials: YS
authors.lastname: Shin
authors.forename: S Y
authors.initials: SY
authors.lastname: Kim
mesh_terms: D000086:Acetazolamide; D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001810:Blood Volume / Q000502:physiology; D002257:Carbonic Anhydrase Inhibitors; D002533:Cerebral Angiography; D002536:Cerebral Arteries / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003545:Cysteine / Q000031:analogs & derivatives; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009072:Moyamoya Disease / Q000175:diagnosis / Q000503:physiopathology*; D015609:Organotechnetium Compounds; D055420:Perfusion Imaging; D012016:Reference Values; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D015609:Organotechnetium Compounds; C059659:technetium Tc 99m bicisate; D003545:Cysteine; D000086:Acetazolamide