title: Time and diffusion lesion size in major anterior circulation ischemic strokes.
abstract: OBJECTIVE
  Major anterior circulation ischemic strokes caused by occlusion of the distal internal carotid artery or proximal middle cerebral artery or both account for about one third of ischemic strokes with mostly poor outcomes. These strokes are treatable by intravenous tissue-type plasminogen activator and endovascular methods. However, dynamics of infarct growth in these strokes are poorly documented. The purpose was to help understand infarct growth dynamics by measuring acute infarct size with diffusion-weighted imaging (DWI) at known times after stroke onset in patients with documented internal carotid artery/middle cerebral artery occlusions.
  
  
  METHODS
  Retrospectively, we included 47 consecutive patients with documented internal carotid artery/middle cerebral artery occlusions who underwent DWI within 30 hours of stroke onset. Prospectively, 139 patients were identified using the same inclusion criteria. DWI lesion volumes were measured and correlated to time since stroke onset. Perfusion data were reviewed in those who underwent perfusion imaging.
  
  
  RESULTS
  Acute infarct volumes ranged from 0.41 to 318.3 mL. Infarct size and time did not correlate (R2=0.001). The majority of patients had DWI lesions that were <25% the territory at risk (<70 mL) whether they were imaged <8 or >8 hours after stroke onset. DWI lesions corresponded to areas of greatly reduced perfusion.
  
  
  CONCLUSIONS
  Poor correlation between infarct volume and time after stroke onset suggests that there are factors more powerful than time in determining infarct size within the first 30 hours. The observations suggest that highly variable cerebral perfusion via the collateral circulation may primarily determine infarct growth dynamics. If verified, clinical implications include the possibility of treating many patients outside traditional time windows.
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: Reza
authors.initials: R
authors.lastname: Hakimelahi
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: Behroze A
authors.initials: BA
authors.lastname: Vachha
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: William A
authors.initials: WA
authors.lastname: Copen
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: Giacomo D E
authors.initials: GD
authors.lastname: Papini
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: Julian
authors.initials: J
authors.lastname: He
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: Mahmoud M
authors.initials: MM
authors.lastname: Higazi
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Lev
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: Pamela W
authors.initials: PW
authors.lastname: Schaefer
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Yoo
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston.
authors.forename: Lee H
authors.initials: LH
authors.lastname: Schwamm
authors.affiliation: From the Neuroradiology Division and the Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston. rggonzalez@mgh.harvard.edu.
authors.forename: R Gilberto
authors.initials: RG
authors.lastname: González
mesh_terms: D000368:Aged; D001921:Brain / Q000098:blood supply* / Q000473:pathology*; D002545:Brain Ischemia / Q000473:pathology; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation / Q000502:physiology; D003097:Collateral Circulation / Q000502:physiology; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D020521:Stroke / Q000473:pathology*; D013997:Time Factors
keywords: brain infarction; diffusion; magnetic resonance imaging; stroke