title: First-pass quantitative CT perfusion identifies thresholds for salvageable penumbra in acute stroke patients treated with intra-arterial therapy.
abstract: OBJECTIVE
  The purpose of this study was to determine whether, in acute stroke patients treated with intra-arterial (IA) recanalization therapy, CT perfusion (CTP) can distinguish ischemic brain tissue destined to infarct from that which will survive.
  
  
  METHODS
  Dynamic CTP was obtained in 14 patients within 8 hours of stroke onset, before IA therapy. Initial quantitative cerebral blood volume (CBV) and flow (CBF) values were visually segmented and normalized in the "infarct core" (region 1: reduced CBV and CBF, infarction on follow-up), "penumbra that infarcts" (region 2: normal CBV, reduced CBF, infarction on follow-up), and "penumbra that recovers" (region 3: normal CBV, reduced CBF, normal on follow-up). Normalization was accomplished by dividing the ischemic region of interest value by that of a corresponding, contralateral, uninvolved region, which resulted in CBV and CBF "ratios." Separate CBV and CBF values were obtained in gray matter (GM) and white matter (WM).
  
  
  RESULTS
  Mean CBF ratios for regions 1, 2, and 3 were 0.19 +/- 0.06, 0.34 +/- 0.06, and 0.46 +/- 0.09, respectively (all P < .001). Mean CBV ratios for regions 1, 2, and 3 were similarly distinct (all P < .05). Absolute CBV and CBF values for regions 2 and 3 were not significantly different. All regions with CBF ratio <0.32, CBV ratio <0.68, CBF <12.7 mL/100 g/min, or CBV <2.2 mL/100 g infarcted. No region with CBF ratio >0.44 infarcted. GM versus WM CBF and CBV values were significantly different for region 2 compared with region 3 (P < .05).
  
  
  CONCLUSIONS
  In acute stroke patients, quantitative CTP can distinguish ischemic tissue likely to infarct from that likely to survive.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: P W
authors.initials: PW
authors.lastname: Schaefer
authors.forename: L
authors.initials: L
authors.lastname: Roccatagliata
authors.forename: C
authors.initials: C
authors.lastname: Ledezma
authors.forename: B
authors.initials: B
authors.lastname: Hoh
authors.forename: L H
authors.initials: LH
authors.lastname: Schwamm
authors.forename: W
authors.initials: W
authors.lastname: Koroshetz
authors.forename: R G
authors.initials: RG
authors.lastname: Gonzalez
authors.forename: M H
authors.initials: MH
authors.lastname: Lev
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D001921:Brain / Q000000981:diagnostic imaging*; D002544:Cerebral Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D005260:Female; D006801:Humans; D007269:Injections, Intra-Arterial; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000503:physiopathology; D015912:Thrombolytic Therapy; D036542:Tomography, Spiral Computed
chemical_list: D003287:Contrast Media; D007472:Iohexol