title: Detection of misery perfusion in the cerebral hemisphere with chronic unilateral major cerebral artery steno-occlusive disease using crossed cerebellar hypoperfusion: comparison of brain SPECT and PET imaging.
abstract: OBJECTIVE
  In patients with unilateral internal carotid or middle cerebral artery (ICA or MCA) occlusive disease, the degree of crossed cerebellar hypoperfusion that is evident within a few months after the onset of stroke may reflect cerebral metabolic rate of oxygen in the affected cerebral hemisphere relative to that in the contralateral cerebral hemisphere. The aim of the present study was to determine whether the ratio of blood flow asymmetry in the cerebellar hemisphere to blood flow asymmetry in the cerebral hemisphere on positron emission tomography (PET) and single photon emission computed tomography (SPECT) correlates with oxygen extraction fraction (OEF) asymmetry in the cerebral hemisphere on PET in patients with chronic unilateral ICA or MCA occlusive disease and whether this blood flow ratio on SPECT detects misery perfusion in the affected cerebral hemisphere in such patients.
  
  
  METHODS
  Brain blood flow and OEF were assessed using (15)O-PET and N-isopropyl-p-[(123)I]iodoamphetamine ((123)I-IMP) SPECT, respectively. All images were anatomically standardized using SPM2. A region of interest (ROI) was automatically placed in the bilateral MCA territories and in the bilateral cerebellar hemispheres using a three-dimensional stereotaxic ROI template, and affected-to-contralateral asymmetry in the MCA territory or contralateral-to-affected asymmetry in the cerebellar hemisphere was calculated. Sixty-three patients with reduced blood flow in the affected cerebral hemisphere on (123)I-IMP SPECT were enrolled in this study.
  
  
  RESULTS
  A significant correlation was observed between MCA ROI asymmetry of PET OEF and the ratio of cerebellar hemisphere asymmetry of blood flow to MCA ROI asymmetry of blood flow on PET (r = 0.381, p = 0.0019) or SPECT (r = 0.459, p = 0.0001). The correlation coefficient was higher when reanalyzed in a subgroup of 43 patients undergoing a PET study within 3 months after the last ischemic event (r = 0.541, p = 0.0001 for PET; r = 0.609, p < 0.0001 for SPECT). The blood flow ratio on brain perfusion SPECT in all patients provided 100 % sensitivity and 58 % specificity, with 43 % positive and 100 % negative predictive values for detecting abnormally elevated MCA ROI asymmetry of PET OEF.
  
  
  CONCLUSIONS
  The ratio of blood flow asymmetry in the cerebellar hemisphere to blood flow asymmetry in the cerebral hemisphere on PET and SPECT correlates with PET OEF asymmetry in the cerebral hemisphere, and this blood flow ratio on SPECT detects misery perfusion in the affected cerebral hemisphere.
authors.affiliation: Department of Neurosurgery, Iwate Medical University, 19-1 Uchimaru, Morioka, 020-8505, Japan.
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ogasawara
authors.forename: Hideo
authors.initials: H
authors.lastname: Saito
authors.forename: Kazunori
authors.initials: K
authors.lastname: Terasaki
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ogasawara
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Yoshida
authors.forename: Takaaki
authors.initials: T
authors.lastname: Beppu
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Kubo
authors.forename: Shunrou
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Eiki
authors.initials: E
authors.lastname: Tsushima
authors.forename: Akira
authors.initials: A
authors.lastname: Ogawa
mesh_terms: D000328:Adult; D000368:Aged; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016022:Case-Control Studies; D002531:Cerebellum / Q000098:blood supply / Q000000981:diagnostic imaging; D002540:Cerebral Cortex / Q000098:blood supply / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging; D049268:Positron-Emission Tomography; D015899:Tomography, Emission-Computed, Single-Photon