Perfusion CT in patients with acute ischemic stroke treated with intra-arterial thrombolysis: predictive value of infarct core size on clinical outcome.

BACKGROUND AND
PURPOSE: A potential role of perfusion CT (PCT) in selecting patients with stroke for reperfusion therapies has been recently advocated. The purpose of the study was to assess the reliability of PCT in predicting clinical outcome of patients with acute ischemic stroke treated with intra-arterial thrombolysis (IAT).
MATERIALS AND METHODS: Twenty-seven patients with acute hemispheric ischemic stroke were investigated with PCT and treated with IAT between 3 and 6 hours of stroke onset. The infarct core was outlined on cerebral blood volume (CBV) maps by using accepted viability thresholds. The penumbra was defined as time-to-peak (TTP)-CBV mismatch. Clinical outcome was assessed by modified Rankin Scale (mRS) scores at 3 months and dichotomized into favorable (mRS score, 0-2) and unfavorable (mRS score, 3-6). Data were retrospectively analyzed by multiple regression to identify predictors of clinical outcome among the following variables: age, sex, National Institutes of Health Stroke Scale score, serum glucose level, thrombolytic agent, infarct core and mismatch size, collateral circulation, time to recanalization, and recanalization rate after IAT.
RESULTS: Patients with favorable outcome had smaller cores (P = .03), increased mismatch ratios (P = .03), smaller final infarct sizes (P < .01), higher recanalization rates (P = .03), and reduced infarct growth rates (P < .01), compared with patients with unfavorable outcome. The core size was the strongest predictor of clinical outcome in an "all subset" model search (P = .01; 0.96 point increase in mRS score per any increment of 1 SD; 95% confidence interval, +0.17 to +1.75).
CONCLUSIONS: PCT is a reliable tool for the identification of irreversibly damaged brain tissue and for the prediction of clinical outcome of patients with acute stroke treated with IAT.