title: White matter thresholds for ischemic penumbra and infarct core in patients with acute stroke: CT perfusion study.
abstract: OBJECTIVE
  To prospectively determine the parameters derived at admission computed tomographic (CT) perfusion imaging admission that best differentiate ischemic white matter that recovers from that which infarcts, with the latter retrospectively defined at a CT examination performed without contrast material (unenhanced CT) 5-7 days after the event.
  
  
  METHODS
  Ethics committee approval and informed consent were obtained. Thirty patients with stroke underwent unenhanced CT, CT angiography, and CT perfusion studies at admission. Additionally, CT angiography was performed 24 hours after the stroke, and an unenhanced CT study was performed 5-7 days after the stroke. Five patients were excluded; the remaining patients (10 men, 15 women; mean age, 70 years +/- 13 [standard deviation]) were separated into those with recanalization (n = 16) and those without recanalization (n = 9) at 24 hours. For patients with recanalization, the final infarct was outlined on unenhanced CT images obtained 5-7 days after the event and was superimposed on coregistered maps from the CT perfusion study performed at admission. Ischemic white matter tissue (cerebral blood flow [CBF] < 14 mL/min/100 g) was identified at the admission CT perfusion study, and the penumbra was defined as the difference between the ischemic region and the infarct region.
  
  
  RESULTS
  Infarct regions showed a matched decrease in CBF and cerebral blood volume (CBV) at admission, whereas penumbra regions showed a significant (P < .05) decrease in CBF but no change in CBV (P > .05) from contralateral values. A threshold CBF . CBV value of 8.14 was the most sensitive (95%, 20 of 21 regions) and specific (94%, 32 of 34 regions) parameter for differentiating between regions of ischemic white matter that recovered and regions of ischemic white matter that infarcted.
  
  
  CONCLUSIONS
  The product of CBF and CBV derived from CT perfusion data provided the best differentiation between regions of ischemic white matter that infarcted and regions of ischemic white matter that recovered 5-7 days after a stroke.
authors.affiliation: Department of Imaging, Lawson Health Research Institute, London, Ontario, Canada.
authors.forename: Blake D
authors.initials: BD
authors.lastname: Murphy
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Fox
authors.forename: Donald H
authors.initials: DH
authors.lastname: Lee
authors.forename: Demetrios J
authors.initials: DJ
authors.lastname: Sahlas
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Black
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hogan
authors.forename: Shelagh B
authors.initials: SB
authors.lastname: Coutts
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Demchuk
authors.forename: Mayank
authors.initials: M
authors.lastname: Goyal
authors.forename: Richard I
authors.initials: RI
authors.lastname: Aviv
authors.forename: Sean
authors.initials: S
authors.lastname: Symons
authors.forename: Irene B
authors.initials: IB
authors.lastname: Gulka
authors.forename: Vadim
authors.initials: V
authors.lastname: Beletsky
authors.forename: David
authors.initials: D
authors.lastname: Pelz
authors.forename: Richard K
authors.initials: RK
authors.lastname: Chan
authors.forename: Ting-Yim
authors.initials: TY
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D001810:Blood Volume; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D020521:Stroke / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D007472:Iohexol