title: The MRA-DWI mismatch identifies patients with stroke who are likely to benefit from reperfusion.
abstract: OBJECTIVE
  The aim of this exploratory analysis was to evaluate if a combination of MR angiography (MRA) and diffusion-weighted imaging (DWI) selection criteria can be used to identify patients with acute stroke who are likely to benefit from early reperfusion.
  
  
  METHODS
  Data from DEFUSE, a study of 74 patients with stroke who received intravenous tissue plasminogen activator in the 3- to 6-hour time window and underwent MRIs before and approximately 4 hours after treatment were analyzed. The MRA-DWI mismatch model was defined as (1) a DWI lesion volume less than 25 mL in patients with a proximal vessel occlusion; or (2) a DWI lesion volume less than 15 mL in patients with proximal vessel stenosis or an abnormal finding of a distal vessel. Favorable clinical response was defined as an improvement on the National Institutes of Health Stroke Scale score of at least 8 points between baseline and 30 days or a National Institutes of Health Stroke Scale score </=1 at 30 days.
  
  
  RESULTS
  Twenty-seven of 62 patients (44%) had an MRA-DWI mismatch. There was a differential response to early reperfusion based on MRA-DWI mismatch status. Reperfusion was associated with an increased rate of a favorable clinical response in patients with an MRA-DWI mismatch (OR, 12.5; 95% CI, 1.8 to 83.9) and a lower rate in patients without mismatch (OR, 0.2; 95% CI, 0.0 to 0.8).
  
  
  CONCLUSIONS
  The MRA-DWI mismatch model appears to identify patients with stroke who are likely to benefit from reperfusion therapy administered in the 3- to 6-hour time window after symptom onset. The criteria established for the MRA-DWI mismatch model in this study require validation in an independent cohort.
authors.affiliation: Stanford Stroke Center, 701 Welch Road, Suite B325, Palo Alto, CA 94304-9705, USA. lansberg@stanford.edu
authors.forename: Maarten G
authors.initials: MG
authors.lastname: Lansberg
authors.forename: Vincent N
authors.initials: VN
authors.lastname: Thijs
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Olivot
authors.forename: Michael P
authors.initials: MP
authors.lastname: Marks
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Wechsler
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kemp
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Albers
mesh_terms: D000368:Aged; D001921:Brain / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology; D002545:Brain Ischemia; D002536:Cerebral Arteries / Q000473:pathology; D002560:Cerebrovascular Circulation; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D018450:Disease Progression; D004632:Emergency Medical Services / Q000592:standards; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D018810:Magnetic Resonance Angiography / Q000379:methods* / Q000592:standards; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D012720:Severity of Illness Index; D020521:Stroke / Q000175:diagnosis* / Q000188:drug therapy*; D015912:Thrombolytic Therapy / Q000592:standards*; D013997:Time Factors; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*; D016896:Treatment Outcome; D014894:Weights and Measures
chemical_list: D010959:Tissue Plasminogen Activator