Abstract 321: Net Water Uptake as a Marker Linking Endovascular Therapy Results to Brain Edema Development in Ischemic Stroke

Introduction/Purpose Several randomized clinical trials have demonstrated the benefit of endovascular treatment (EVT) over intravenous thrombolysis for large vessel occlusion (LVO) in acute ischemic stroke (AIS). However, postoperative brain edema and consequent hemorrhagic transformation remain the most dangerous EVT complications, which might lead to brain herniation due to malignant brain swelling. A new densitometric parameter (net water uptake ‐ NWU) can measure brain edema on computed tomography (CT). Because favorable and unfavorable EVT outcome subgroups are underrepresented in previous thrombectomy studies, we hypothesized that edema progression would depend on recanalization status. The aim was to study changes in brain tissue hydration using quantitative NWU in comparison to EVT results at LVO. Materials/Methods This retrospective, non‐randomized, observational, single‐center study included 137 patients (women 67; men 70, age 63 years [59;67]) with acute ischemic stroke (AIS) resulting from large vessel occlusion (LVO) in the anterior circulation who underwent endovascular treatment (EVT). The protocol was reviewed and approved by the Institutional Ethical Committee. Inclusion criteria: (1) AIS due to LVO of the M1 segment of the middle cerebral artery or distal internal carotid artery; (2) hospital admission within 12 hours after known onset; (3) computed tomography (CT) performed with Alberta Stroke Program Early CT Score (ASPECTS) of ≥5 without signs of intracerebral hemorrhage; (4) availability of follow‐up CT within 24 hours after symptom onset without signs of intracerebral hemorrhage. Ischemic zones were established using multiphase perfusion CT (PCT) at admission on a 160‐slice scanner (Canon Aquilion Prime, Japan), with thresholds of cerebral blood volume <2.0 ml/100 g and mean transit time >145% compared with the contralateral hemisphere. Net water uptake (NWU) in ischemic zones was calculated using non‐contrast CT at admission and follow‐up after EVT using the following equation NWU = (1 ‐ D ischemia / D normal ) × 100%, where D ischemia is the ischemic “penumbra” density (Hounsfield unit) and D normal is the density of normal brain tissue in the symmetrical zone of the contralateral hemisphere. EVT was performed under general anesthesia or conscious sedation using approved devices, including stent retrievers and aspiration catheters. Data are shown as median [interquartile range]. Analysis of variance (ANOVA) models were performed. Pearson's correlation coefficients were used to assess agreement between computed variables. Regression lines and confidence limits are for illustrative purposes only. P<0.05 was considered statistically significant. Results NWU at admission was significantly lower in the successful EVT group (median 3.4%) than in the unsuccessful group (5.1%; p<0.05). Follow‐up NWU rose in both cohorts but remained lower after successful reperfusion (7.2% vs. 12.8%; p<0.001). The relative NWU increase was ∼2‐fold with successful EVT and ∼3‐fold when reperfusion failed. 53 patients had successful vessel recanalization (Thrombolysis in Cerebral Infarction 2b‐3), while 84 had persistent or recurrent LVO (TICI 0‐2a). Conclusion Successful EVT correlates with reduced brain edema development as measured by NWU, highlighting the importance of recanalization status in mitigating ischemic injury and potential complications like hemorrhagic transformation. These findings underscore NWU as a valuable tool for predicting edema progression and guiding post‐EVT management in AIS patients with LVO.