Permeability measures predict hemorrhagic transformation after ischemic stroke

Objective: We sought to examine the diagnostic utility of existing predictors of any hemorrhagic transformation (HT) and compare them with new perfusion imaging permeability measures in ischemic stroke patients receiving alteplase only. Methods: A pixel-based analysis of pretreatment CT perfusion (CTP) was undertaken to define the optimal CTP permeabilit thresholds to predict the likelihood of HT. We then compared previously proposed predictors of HT using regression analyses and receiver operating characteristic curve analysis to produce an area under the curve (AUC). We compared AUCs using χ² analysis. Results: From 5 centers, 1,407 patients were included in this study; of these, 282 had HT. The cohort was split into a derivation cohort (1,025, 70% patients) and a validation cohort (382 patients or 30%). The extraction fraction (E) permeability map at a threshold of 30% relative to contralateral had the highest AUC at predicting any HT (derivation AUC 0.85, 95% confidence interval [CI], 0.79–0.91; validation AUC 0.84, 95% CI 0.77–0.91). The AUC improved when permeability was assessed within the acute perfusion lesion for the E maps at a threshold of 30% (derivation AUC 0.91, 95% CI 0.86–0.95; validation AUC 0.89, 95% CI 0.86–0.95). Previously proposed associations with HT and parenchymal hematoma showed lower AUC values than the permeability measure. Interpretation: In this large multicenter study, we have validated a highly accurate measure of HT prediction. This measure might be useful in clinical practice to predict hemorrhagic transformation in ischemic stroke patients before receiving alteplase alone.