ABSTRACT NUMBER: ESOC2026A1277 WHITE MATTER INJURY SEVERITY IS ASSOCIATED WITH WORSE FUNCTIONAL OUTCOME AFTER ISCHEMIC STROKE: A GRADED, TISSUE-SPECIFIC ADC AND KURTOSIS ANALYSIS

Abstract Background and aims Recent trials showing benefit of reperfusion therapy despite large ischemic cores and minimal perfusion mismatch have challenged the traditional infarct-versus-no-infarct dichotomy and support a more graded view of ischemic injury. This study investigates how the severity of white- and grey-matter injury within an infarct relates to functional outcomes. Methods This analysis of the Post-Reperfusion-pathophysiology-in-Acute-Ischemic-StrokE (PRAISE) multicentre observational study included adults with anterior circulation large-vessel-occlusion ischemic stroke who underwent 24-hour follow-up MRI post-thrombectomy. Segmented diffusion lesions were subdivided into white- and grey-matter components and overlaid on apparent diffusion coefficient (ADC) and mean kurtosis (MK) maps. Severe injury fractions, calculated for total, white-, and grey-matter lesion components as the proportion of voxels in the infarct lesion that exhibited values beyond the 1st (ADC) and 99th (MK) percentile voxel value of the contralateral homologous region, were tested in logistic regression models (age, lesion volume, NIHSS) to assess independent associations with 90-day functional independence (mRS 0-2). Results In 63 patients analyzed (median age 72yo, 57% male, 60.32% mRS 0-2), white-matter severe injury fraction was independently associated with outcome for both ADC and MK metrics, with each 1% increase associated with lower odds of functional independence (ADC: aOR 0.95, 95%CI 0.91-0.99, p=0.040; MK: aOR 0.96, 95%CI 0.92-0.99, p=0.043). In contrast, no significant association was found for grey-matter fractions. Conclusions Greater white-matter severity of injury within an infarct is associated with poor functional outcome, underscoring the importance of white-matter integrity in post-stroke recovery and supporting a graded and tissue-specific approach to infarct assessment. Conflict of interest Samantha Rivet: Nothing to disclose. Christopher Steward: Nothing to disclose. Valerian Altersberger: Nothing to disclose. Leonid Churilov: Nothing to disclose. Peter Mitchell: Nothing to disclose. Vincent Thijs: Nothing to disclose. Patricia Desmond: Nothing to disclose. Vijay Venkatraman: Nothing to disclose. Stephen Davis: Nothing to disclose. Bruce Campbell: Nothing to disclose. Felix Ng: Nothing to disclose.