ASPECTS-based net water uptake outperforms target mismatch for outcome prediction in patients with acute ischemic stroke and late therapeutic window

Objective To compare the prognostic value of net water uptake (NWU) and target mismatch (TM) on CT perfusion (CTP) in acute ischemic stroke (AIS) patients with late time window. Methods One hundred and nine consecutive AIS patients with anterior-circulation large vessel occlusion presenting within 6–24 h from onset/last seen well were enrolled. Automated Alberta Stroke Program Early CT Score–based NWU (ASPECTS-NWU) was calculated from admission CT. The correlation between ASPECTS-NWU and CTP parameters was assessed. Predictors for favorable outcome (modified Rankin Scale score ≤ 2) at 90 days were assessed using logistic regression analysis. The ability of outcome prediction between ASPECTS-NWU and TM (an ischemic core < 70 mL, a mismatch ratio ≥ 1.8, and an absolute difference ≥ 15 mL) was compared using receiver operating characteristic (ROC) curve. Results A higher level of ASPECTS-NWU was associated with a larger ischemic core ( r = 0.66, p < 0.001) and a larger hypoperfusion volume ( r = 0.38, p < 0.001). ASPECTS-NWU performed better than TM for outcome stratification (area under the curve [AUC], 0.738 vs 0.583, p = 0.004) and was the only independent neuroimaging marker associated with favorable outcomes compared with CTP parameters (odds ratio, 0.73; 95% confidence interval [CI] 0.62–0.87, p < 0.001). An outcome prediction model including ASPECTS-NWU and clinical variables (National Institutes of Health Stroke Scale scores and age) yielded an AUC of 0.828 (95% CI 0.744–0.893; sensitivity 65.4%; specificity 87.7%). Conclusion ASPECTS-NWU performed better than TM for outcome prediction in AIS patients with late time window and might be an alternative imaging biomarker to CTP for patient selection. Clinical relevance statement Automated Alberta Stroke Program Early CT Score–based net water uptake outperforms target mismatch on CT perfusion for the outcome prediction in patients with acute ischemic stroke and can be an alternative imaging biomarker for patient selection in late therapeutic window. Key Points • A higher ASPECTS-based net water uptake was associated with larger ischemic cores and hypoperfusion volumes on CT perfusion. • ASPECTS-based net water uptake outperformed target mismatch for outcome prediction in acute ischemic stroke with extended therapeutic window. • ASPECTS-based net water uptake can be an alternative biomarker to target mismatch for selecting acute ischemic stroke patients with late therapeutic window.