title: Quantitative assessment of core/penumbra mismatch in acute stroke: CT and MR perfusion imaging are strongly correlated when sufficient brain volume is imaged.
abstract: OBJECTIVE
  Our purpose was to determine (1) the correlation between quantitative CT and MR measurements of infarct core, penumbra, and mismatch; and (2) whether the difference between these measurements would alter patient selection for stroke clinical trials.
  
  
  METHODS
  We studied 45 patients with acute middle cerebral artery stroke imaged a mean of 3.8 hours after onset (range, 0.48 to 8.35 hours) who underwent CT perfusion and MR diffusion (DWI)/perfusion imaging within 3 hours of each other. The DWI and MR-mean transit time (MTT) abnormalities were visually segmented using a semiautomated commercial analysis program. The CT-cerebral blood volume) and CT-MTT lesions were automatically segmented using a relative cerebral blood volume threshold of 0.56 and a relative MTT threshold of 1.50 on commercially available software. Percent mismatch was defined as [(MTT-DWI)/DWI volume]x100. Pearson correlation coefficients were calculated.
  
  
  RESULTS
  There were significant correlations for DWI versus CT-cerebral blood volume lesion volumes (r2=0.88, P<0.001), for MR-MTT versus CT-MTT lesion volumes(r2=0.86, P<0.001), and for MR-MTT/DWI versus CT-MTT/CT-cerebral blood volume mismatch lesion volumes(r2=0.81, P<0.001). MR perfusion and CT perfusion agreed for determining: (1) infarct core < versus >or=100 mL in 41 of 45 (91.1%); (2) MTT lesion size < versus >2 cm diameter in 42 of 45 (93.3%); (3) mismatch < versus >20% in 41 of 45 (91.1%); and (4) inclusion versus exclusion from trial enrollment in 38 of 45 (84.4%) patients. Six of 7 disagreements were due to inadequate CT coverage.
  
  
  CONCLUSIONS
  Advanced MR and CT perfusion imaging measurements of core/penumbra mismatch for patient selection in stroke trials are highly correlated when CT perfusion coverage is sufficient to include most of the ischemic region. Although MR is currently the preferred imaging method for determining core and penumbra, CT perfusion is comparable and potentially more available.
authors: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. pschaefer@partners.org
authors: Pamela W
authors: PW
authors: Schaefer
authors: Elizabeth R
authors: ER
authors: Barak
authors: Shahmir
authors: S
authors: Kamalian
authors: Leila Rezai
authors: LR
authors: Gharai
authors: Lee
authors: L
authors: Schwamm
authors: Ramon Gilberto
authors: RG
authors: Gonzalez
authors: Michael H
authors: MH
authors: Lev
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002560:Cerebrovascular Circulation / Q000502:physiology; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D012039:Regional Blood Flow; D012189:Retrospective Studies; D013223:Statistics as Topic; D020521:Stroke / Q000473:pathology*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods