Perfusion MR Predicts Outcome in High-Risk Transient Ischemic Attack/Minor Stroke A Derivation-Validation Study

Background and Purpose 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 (T(max)4 s), mismatch (T(max)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.