title: Quantitative assessment of cerebral hemodynamics using perfusion-weighted MRI in patients with major cerebral artery occlusive disease: comparison with positron emission tomography.
abstract: OBJECTIVE
  Cerebrovascular reactivity (CVR) to acetazolamide is a key parameter in determining the severity of hemodynamic impairment in patients with major cerebral artery occlusive disease. Perfusion-weighted MRI (PW MRI) can measure the cerebral blood volume (CBV) as an indicator of hemodynamic impairment. CBV measured by PW MRI was compared with CVR measured by positron emission tomography (PET).
  
  
  METHODS
  Twelve normal subjects and 17 patients with major cerebral artery occlusive disease underwent PW MRI and PET. The images were coregistered with 3-dimensional spoiled gradient-recalled acquisition images. Quantitative PW MRI-CBV maps were generated using the indicator dilution method with arterial input function. One large cortical region of interest for each unilateral middle cerebral artery territory was determined on each image. PET-CVR was calculated by measuring cerebral blood flow before and after acetazolamide challenge.
  
  
  RESULTS
  A significant negative correlation was observed between PW MRI-CBV and PET-CVR (r=-0.713; P<0.0001). PW MRI-CBV higher than the mean +2 SD obtained in normal subjects (15.2 mL/100 g) was defined as elevated and PET-CVR lower than the mean -2 SD obtained in normal subjects (15.1%) was defined as reduced. Assuming the PET-CVR as the true determinant of hemodynamic impairment, PW MRI-CBV provided 80.0% sensitivity and 91.7% specificity, with 80.0% positive predictive value for detecting patients with reduced CVR.
  
  
  CONCLUSIONS
  The PW MRI-CBV method can simply and accurately identify patients with hemodynamic impairment without exposure to ionizing radiation.
authors.affiliation: Department of Neurosurgery, School of Medicine, Iwate Medical University, Morioka, Iwate 020-8505, Japan.
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Endo
authors.forename: Takashi
authors.initials: T
authors.lastname: Inoue
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ogasawara
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fukuda
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kanbara
authors.forename: Akira
authors.initials: A
authors.lastname: Ogawa
mesh_terms: D000328:Adult; D000368:Aged; D001157:Arterial Occlusive Diseases / Q000175:diagnosis* / Q000473:pathology; D001921:Brain / Q000098:blood supply*; D002536:Cerebral Arteries / Q000473:pathology; D002560:Cerebrovascular Circulation; D005260:Female; D006439:Hemodynamics; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D012372:ROC Curve; D012008:Recurrence; D012306:Risk; D012680:Sensitivity and Specificity; D020521:Stroke / Q000473:pathology; D013997:Time Factors