ABSTRACT NUMBER: ESOC2026YS36 APPARENT DIFFUSION COEFFICIENT GRADIENT COMPOSITION AND FUNCTIONAL OUTCOME AFTER ENDOVASCULAR THROMBECTOMY IN LARGE ISCHEMIC CORE STROKE

Abstract Background and aims In acute ischemic stroke with large ischemic cores (LCI), outcomes remain heterogeneous despite similar infarct volumes. We examined whether apparent diffusion coefficient (ADC) composition relative to the initial diffusion-weighted imaging (DWI) lesion and within-lesion ADC heterogeneity are associated with functional outcome in patients with LCI after endovascular thrombectomy (EVT). Methods We retrospectively analyzed 134 patients with large vessel occlusion who underwent EVT with successful reperfusion and had LCI (baseline DWI volume >50 mL). Within the initial DWI lesion, ADC composition was quantified as three fractions (low <540, mid 540–620, and high >620 ×10-6 mm2/s) relative to total DWI volume. Lesion heterogeneity was assessed using Shannon entropy derived from the ADC value distribution. The primary outcome was good functional outcome (modified Rankin Scale [mRS] 0–3) at 3-month, evaluated using adjusted logistic regression. Results Among 134 patients (age 70.9 ± 12.2 years; 61.2% male; DWI volume 89.4 ± 40.2mL), 40.3% achieved mRS 0–3 at 3 months. In adjusted analyses, the mid-range ADC fraction showed the strongest association with favorable outcome (OR 2.46 per 5% increase; 1.31–4.89). ADC heterogeneity was also associated with favorable outcome (OR 1.66 per 0.1 unit; P=0.013). The mid-range ADC fraction demonstrated the highest discriminative performance among ADC-based metrics (AUC 0.795; 0.720–0.871). In EVT-treated patients with LCI, a higher proportion of mid-ADC fraction (540–620) was associated with better functional outcome. These hypothesis-generating findings suggest that ADC composition may contribute to outcome heterogeneity in LCI populations and warrant prospective validation. Conflict of interest H Kim: nothing to disclosure Figure 1 - belongs to Results