Perfusion MR predicts outcome in high-risk transient ischemic attack/minor stroke: a derivation-validation study

Area of Science:

• Neurology
• Radiology
• Stroke Medicine

Background:

• Transient ischemic attack (TIA) and minor ischemic stroke carry an early risk of clinical deterioration.
• Perfusion-diffusion mismatch on baseline imaging may identify patients at higher risk.

Purpose of the Study:

• To evaluate the predictive value of baseline perfusion-diffusion mismatch for infarct growth and clinical deterioration in patients with high-risk TIA and minor stroke.
• To determine an optimal threshold for mismatch volume in predicting these outcomes.

Main Methods:

• Prospective enrollment of high-risk TIA and minor stroke patients (NIH Stroke Scale ≤3) within 24 hours of symptom onset.
• MRI including diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) to assess mismatch (PWI-DWI).
• Measurement of infarct growth and symptom progression on follow-up imaging (FLAIR).

Main Results:

• Infarct growth occurred in 18.5% of the derivation cohort and 5.5% of the validation cohort.
• Baseline mismatch significantly predicted infarct growth (RR, 13.5) and symptom progression (RR, 7.0) in the derivation cohort.
• A mismatch volume of 10 mL was optimal for predicting infarct growth, showing high predictive value in both cohorts (AUC 0.89 and P=0.001).
• Baseline mismatch was associated with clinical deterioration in both derivation (AUC 0.81) and validation (AUC 0.66) cohorts.

Conclusions:

• Diffusion-weighted imaging-perfusion-weighted imaging mismatch is a strong predictor of infarct growth and clinical deterioration in patients with high-risk TIA and minor stroke.
• These findings support the use of reperfusion strategies in this patient population to mitigate adverse outcomes.