A TENSION trial analysis found that early cerebral edema quantified on CT may help identify adults with large-core anterior circulation stroke who benefit from endovascular thrombectomy (EVT). Among 207 adults randomized to EVT plus best medical treatment (BMT) or BMT alone, lower net water uptake (NWU) on admission CT predicted better functional outcomes with EVT. A 15% NWU threshold emerged: patients below this level benefited from EVT, while those ≥15% saw little added advantage. EVT achieved complete reperfusion in 64% of treated adults. NWU, measurable on standard noncontrast CT, may offer a practical biomarker for refining EVT selection.