title: Defining the extent of irreversible brain ischemia using perfusion computed tomography.
abstract: BACKGROUND
  Perfusion computed tomography (PCT) shows promise in acute stroke assessment. However, the accuracy of CT perfusion thresholds in defining the acute infarct core remains uncertain.
  
  
  METHODS
  Concurrent PCT and MRI-DWI performed 3-6 h after symptoms onset were assessed in 57 ischemic stroke patients. PCT was compared to DWI images to define the infarct core using a pixel-based receiver operating characteristic curve analysis to calculate the area under the curve (AUC) for thresholds from PCT maps that were co-registered with the DWI slice location.
  
  
  RESULTS
  A relative cerebral blood flow (CBF) of 45% of the contralateral hemisphere was found to be the most accurate threshold for describing the infarct core (AUC 0.788), and it was also by far the most frequent threshold with the highest AUC across patients.
  
  
  CONCLUSIONS
  CBF thresholds on PCT define the acute infarct core more accurately than do other PCT thresholds, including a cerebral blood volume of 2 ml/100 g.
authors.affiliation: Department of Neurology and Hunter Medical Research Institute, University of Newcastle, Newcastle, N.S.W., Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Bivard
authors.forename: Patrick
authors.initials: P
authors.lastname: McElduff
authors.forename: Neil
authors.initials: N
authors.lastname: Spratt
authors.forename: Christopher
authors.initials: C
authors.lastname: Levi
authors.forename: Mark
authors.initials: M
authors.lastname: Parsons
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation; D038524:Diffusion Magnetic Resonance Imaging; D004185:Disability Evaluation; D006801:Humans; D018810:Magnetic Resonance Angiography; D008875:Middle Aged; D009517:New South Wales; D055420:Perfusion Imaging / Q000379:methods*; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted; D012720:Severity of Illness Index; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult