title: Perfusion MR predicts outcome in high-risk transient ischemic attack/minor stroke: a derivation-validation study.
abstract: OBJECTIVE
  Transient or minor ischemic stroke is associated with an early risk of deterioration. Baseline perfusion-diffusion mismatch may predict clinical deterioration and infarct growth in this population.
  
  
  METHODS
  High-risk transient ischemic attack and minor stroke (National Institutes of Health Stroke Scale ≤3) subjects were prospectively enrolled and imaged with MRI within 24 hours of symptom onset as part of sequential derivation and validation cohorts. Baseline diffusion-weighted imaging, perfusion-weighted imaging (Tmax≥4 s), mismatch (Tmax≥4 s-diffusion-weighted imaging), and follow-up fluid-attenuated inversion recovery infarct volumes were measured. Primary outcome was infarct growth on fluid-attenuated inversion recovery, and secondary outcome was symptom progression.
  
  
  RESULTS
  One hundred thirty-seven and 281 subjects were included in the derivation and validation cohorts, respectively. Infarct growth occurred in 18.5% of the derivation and 5.5% of the validation cohorts. Symptom progression occurred in 9.5% of the derivation and 4.5% of the validation cohorts. In the derivation cohort, subjects with baseline mismatch were significantly more likely to show infarct growth on fluid-attenuated inversion recovery (relative risk [RR], 13.5; 95% confidence interval [CI], 4.2-38.9) and symptom progression (RR, 7.0; 95% CI, 2.0-7.3). A baseline mismatch volume of 10 mL in the derivation cohort was the optimal threshold to predict infarct growth (area under the curve, 0.89; 95% CI, 0.80-0.98). This threshold was highly predictive of infarct growth in the validation cohort (P=0.001). Baseline mismatch was associated with clinical deterioration in the derivation (area under the curve, 0.81; 95% CI, 0.67-0.96) and validation cohorts (area under the curve, 0.66; 95% CI, 0.46-0.85).
  
  
  CONCLUSIONS
  Among subjects with high-risk transient ischemic attack and minor stroke, diffusion-weighted imaging-perfusion-weighted imaging mismatch predicts infarct growth and clinical deterioration. These findings suggest that reperfusion strategies would be beneficial in this population.
authors.affiliation: Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada. negar.asdaghi@ubc.ca
authors.forename: Negar
authors.initials: N
authors.lastname: Asdaghi
authors.forename: Michael D
authors.initials: MD
authors.lastname: Hill
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Coulter
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Butcher
authors.forename: Jayesh
authors.initials: J
authors.lastname: Modi
authors.forename: Abdul
authors.initials: A
authors.lastname: Qazi
authors.forename: Mayank
authors.initials: M
authors.lastname: Goyal
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Demchuk
authors.forename: Shelagh B
authors.initials: SB
authors.lastname: Coutts
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002544:Cerebral Infarction / Q000209:etiology / Q000473:pathology*; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000150:complications / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012306:Risk; D012680:Sensitivity and Specificity; D020521:Stroke / Q000150:complications / Q000175:diagnosis*
keywords: cerebrovascular occlusion; ischemic attack, transient; magnetic resonance imaging; perfusion