title: Parametric Cerebrovascular Reserve Images Using Acetazolamide (99m)Tc-HMPAO SPECT: A Feasibility Study of Quantitative Assessment.
abstract: OBJECTIVE
  Basal/acetazolamide stress (99m)Tc-HMPAO single-photon emission computed tomography (SPECT) has been widely used for evaluation of hemodynamics; however, qualitative and subjective visual assessment of cerebrovascular reserve (CVR) has been performed in clinical settings. The aim of this study was to generate parametric CVR images and evaluate its feasibility of quantification.
  
  
  METHODS
  Basal/acetazolamide stress (99m)Tc-HMPAO SPECT data from 17 patients who underwent bypass surgery or percutaneous transluminal angioplasty were used. Spatial normalization was performed and parametric CVR images were generated using relative CVR (rCVR) of each voxel proportional to CVR of the whole brain. Binary parametric maps to show area of relatively reduced CVR were generated also using threshold of rCVR < 90 %. We calculated rCVR of internal carotid artery (ICA) using the parametric CVR images and probabilistic maps for ICA territory. Pre- and postprocedural parametric CVR images were obtained and quantitative rCVRs were compared. The rCVRs were evaluated according to visual grades for regional decreased CVR.
  
  
  RESULTS
  Postprocedural rCVR obtained from parametric CVR images increased significantly from preprocedural rCVR. The rCVR was significantly correlated with visual grades of reduced CVR for each side of ICA territories.
  
  
  CONCLUSIONS
  We generated parametric CVR images for basal/acetazolamide stress (99m)Tc-HMPAO SPECT. As a quantitative measurement, rCVR obtained from the parametric image was feasibly assessed hemodynamic abnormalities with preserved anatomical information.
authors.affiliation: Department of Nuclear Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Hongyoon
authors.initials: H
authors.lastname: Choi
authors.affiliation: Department of Nuclear Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Min Young
authors.initials: MY
authors.lastname: Yoo
authors.affiliation: Department of Nuclear Medicine, Seoul National University Hospital, Seoul, Korea ; Department of Nuclear Medicine, Seoul National University College of Medicine, 101 Daehangro, Jongro-gu, Seoul, 110-744 Korea.
authors.forename: Gi Jeong
authors.initials: GJ
authors.lastname: Cheon
authors.affiliation: Department of Nuclear Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Keon Wook
authors.initials: KW
authors.lastname: Kang
authors.affiliation: Department of Nuclear Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: June-Key
authors.initials: JK
authors.lastname: Chung
authors.affiliation: Department of Nuclear Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Dong Soo
authors.initials: DS
authors.lastname: Lee
keywords: 99mTc-HMPAO SPECT; Cerebral ischemia; Cerebrovascular reserve; Parametric images