title: Detection of deoxygenation-related signal change in acute ischemic stroke patients by T2*-weighted magnetic resonance imaging.
abstract: OBJECTIVE
  Acute decreases in the MR T2*-weighted signal have been reported in experimental models of middle cerebral artery occlusion. This has been attributed to blood deoxygenation in association with an increased brain oxygen extraction fraction. The aim of this study was to detect this signal by susceptibility-weighted MR imaging in acute ischemic stroke patients.
  
  
  METHODS
  Dynamic susceptibility contrast-enhanced MR (DSC-MR) imaging was performed within 4 hours of stroke onset in 6 patients with unilateral cerebral artery occlusion (middle cerebral artery, n=5; internal carotid artery, n=1). Cerebral blood volume was estimated on a pixel-by-pixel basis. DSC-MR images taken before arrival of the contrast medium were examined visually to identify hypointense areas. Bilateral regions of interest were set in the middle cerebral artery territory for comparison of the mean signal intensity. A semilogarithmic plot of signal intensity versus cerebral blood volume for every pixel in the region of interest was also analyzed.
  
  
  RESULTS
  The side on which the hypointense area was seen was significantly correlated with the side of arterial occlusion. The mean signal intensity was significantly smaller on the affected side than on the contralateral side. The semilogarithmic plot of signal intensity versus cerebral blood volume indicated greater deoxyhemoglobin concentrations for the ipsilateral than for the contralateral region of interest.
  
  
  CONCLUSIONS
  DSC-MR images allow detection of hypointensity in the affected cerebral hemisphere in acute ischemic stroke patients. Such hypointensity may indicate increased oxygen extraction fraction (misery perfusion) and may provide information valuable to patient care.
authors.affiliation: Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita, Japan. hajime@akita-noken.go.jp
authors.forename: Hajime
authors.initials: H
authors.lastname: Tamura
authors.forename: Jun
authors.initials: J
authors.lastname: Hatazawa
authors.forename: Hideto
authors.initials: H
authors.lastname: Toyoshima
authors.forename: Eku
authors.initials: E
authors.lastname: Shimosegawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Okudera
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology; D002545:Brain Ischemia / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D007089:Image Enhancement; D018810:Magnetic Resonance Angiography / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D020521:Stroke / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology
chemical_list: D010100:Oxygen