title: Diffusion-weighted imaging-negative patients with transient ischemic attack are at risk of recurrent transient events.
abstract: OBJECTIVE
  Among patients presenting with a transient ischemic attack (TIA), some clinical features predispose to recurrent TIA, whereas others predispose to subsequent strokes. We assessed the implication of negative diffusion-weighted imaging on a baseline MRI in predicting subsequent TIA.
  
  
  METHODS
  We prospectively studied patients presenting in the emergency department within 12 hours of a TIA (motor or speech). All patients had a MRI within 24 hours of the index event. The primary outcome was TIA within 1 year of study entry. The 1-year risk of stroke was also evaluated.
  
  
  RESULTS
  A total of 85 patients had a MRI, among which 35 patients (41.2%) had a diffusion-weighted imaging lesion. The mean time from symptom onset to MRI was 12.1 hours. Patients without a diffusion-weighted imaging lesion on baseline MRI were 4.6 times (27.4% versus 5.9%; P<0.05) more likely to have a subsequent TIA at 1 year than patients with a diffusion-weighted imaging lesion, but 4.3 times (2.1% versus 9.1%; P=0.19) less likely to have a subsequent stroke.
  
  
  CONCLUSIONS
  The absence of a diffusion-weighted imaging lesion on the baseline scan predicts recurrent transient events rather than stroke.
authors.forename: Jean-Martin
authors.initials: JM
authors.lastname: Boulanger
authors.forename: Shelagh B
authors.initials: SB
authors.lastname: Coutts
authors.forename: Michael
authors.initials: M
authors.lastname: Eliasziw
authors.forename: Suresh
authors.initials: S
authors.lastname: Subramaniam
authors.forename: James
authors.initials: J
authors.lastname: Scott
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Demchuk
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D020520:Brain Infarction / Q000175:diagnosis* / Q000503:physiopathology; D002536:Cerebral Arteries / Q000473:pathology / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors