title: Patients with diffusion-perfusion mismatch on magnetic resonance imaging 48 hours or more after stroke symptom onset: clinical and imaging features.
abstract: BACKGROUND
  Abnormalities in diffusion-weighted (DWI) and perfusion-weighted (PWI) magnetic resonance imaging (MRI) are thought to reflect the presence of brain tissue at risk for ischemic stroke. Many patients with acute ischemic stroke have a mismatch pattern in which the PWI volume is larger than the DWI lesion. This mismatch typically resolves over 24-48 hours. Little is known about the presence of DWI-PWI mismatch in later stages of stroke.
  
  
  METHODS
  This is a retrospective study of 122 patients admitted with a diagnosis of acute ischemic stroke who had DWI and PWI abnormalities on studies performed within 7 days of onset of symptoms. Patients were divided into two groups: those with MRI performed <48 hours and those with MRI performed >or=48 hours from onset of symptoms.
  
  
  RESULTS
  Among 42 patients with MRI performed >or=48 hours after onset of stroke symptoms, 15 of 42 (36%) showed a mismatch pattern, compared to 45 of 80 (56%) in the <48 hours group (P < 0.05). Most of the patients in the >or=48 hours group with mismatch had large artery occlusive disease and many had neurological fluctuations. A subset of these patients were treated with induced hypertension and showed clinical improvement.
  
  
  CONCLUSIONS
  Some patients have persistent DWI-PWI mismatch up to several days after stroke onset. Further studies are needed to determine if these patients should be candidates for reperfusion therapy.
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Angelica
authors.initials: A
authors.lastname: Perez
authors.forename: Lucas
authors.initials: L
authors.lastname: Restrepo
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Kleinman
authors.forename: Peter
authors.initials: P
authors.lastname: Barker
authors.forename: Norman
authors.initials: N
authors.lastname: Beauchamp
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wityk
mesh_terms: D001921:Brain / Q000473:pathology*; D002560:Cerebrovascular Circulation; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000175:diagnosis* / Q000503:physiopathology; D013997:Time Factors