Ischemic Lesion Net Water Uptake for the Prediction of Very Poor Functional Outcomes at 90 Days

Background and Objectives – Recent trials have shown the efficacy of endovascular thrombectomy (EVT) in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO) and large infarcts on admission. However, many patients still experience poor outcomes despite treatment. The aim of this study was to investigate whether quantitative ischemic lesion net water uptake (NWU) on noncontrast head CT (NCCT) could identify AIS-LVO patients with large baseline infarcts who may require constant care or die despite successful EVT.Methods – This retrospective study included AIS-LVO patients with large baseline infarcts (Alberta Stroke Program Early CT Score ≤5) and occlusion of the intracranial internal carotid artery or first (M1) or second (M2) segments of the middle cerebral artery. Patients underwent EVT in 2 centers between 2012 and 2020. NWU was assessed on admission CT images by comparing density measurements of the ischemic core with the matching area of the contralateral hemisphere. The primary end point was a very poor outcome determined by functional neurologic status at 90 days on the modified Rankin Scale (mRS, score 5 or 6). Statistical analyses included group comparisons and evaluation of the predictive accuracy of an NWU ≥11.5% for very poor outcomes.Results – A total of 103 patients with AIS-LVO were included, of whom 57.3% were female, with a mean age of 72.1 years. Among patients with NWU ≥11.5%, 85% experienced very poor outcomes, compared with 51.8% of patients with an NWU <11.5% (p = 0.007). Patients with very poor outcomes had higher mean NWU compared with those without very poor outcomes (10.3% vs 6.0%, p < 0.001). An NWU threshold of 11.5% showed high specificity (93.0%, 95% CI 81.4–97.6) and positive predictive value (85%, 95% CI 64.0–94.8) for predicting very poor outcomes, which increased after combining it with other clinical and imaging parameters.Discussion – Elevated ischemic lesion NWU (≥11.5%) on admission NCCT was strongly associated with very poor functional outcomes at 90 days in AIS-LVO patients with large baseline infarcts treated by EVT. NWU assessment may serve as a valuable imaging biomarker for identifying patients who are likely to require constant care or die despite EVT.