Apparent Diffusion Coefficient Composition and Tissue Heterogeneity as Predictors of Functional Outcomes After Endovascular Thrombectomy in Patients With Large Ischemic Core

BACKGROUND: Recent trials established endovascular thrombectomy efficacy in large ischemic cores, yet outcomes remain heterogeneous despite similar infarct volumes, suggesting that current volumetric assessments may not fully capture tissue viability. We examined whether tissue composition quantified by apparent diffusion coefficient (ADC) distribution and tissue heterogeneity within baseline diffusion-weighted imaging lesions are associated with functional outcomes in large-core patients after successful endovascular thrombectomy. METHODS: We retrospectively analyzed patients with large vessel occlusion with large ischemic cores (diffusion-weighted imaging candidate volume ≥50 mL) achieving successful reperfusion after endovascular thrombectomy. We quantified ADC tissue composition as proportions within 3 ADC ranges relative to total diffusion-weighted imaging lesion volume: low (<540), mid (540–700), and high (>700 × 10 −6 mm 2 /s). Separately, tissue heterogeneity was assessed using Shannon entropy, a metric quantifying ADC distribution heterogeneity. The primary outcome was 3-month good functional outcome (modified Rankin Scale score of 0–3), analyzed via adjusted logistic regression. RESULTS: Among 126 patients (age, 70.8±12.4 years; 60.3% men; diffusion-weighted imaging candidate volume, 93.7±41.2 mL), 39.7% achieved a good functional outcome. Both tissue heterogeneity (adjusted odds ratio, 1.45 per 0.1-unit increase, 1.09–1.93, P =0.011, area under the curve, 0.671) and mid-ADC fraction (adjusted odds ratio, 1.78 per 5% increase, 1.20–2.63, P =0.004, area under the curve, 0.688) were associated with good functional outcomes. Neither low-ADC nor high-ADC fractions showed significant associations with functional outcomes. CONCLUSIONS: Higher mid-ADC (540–700 × 10 −6 mm 2 /s) fraction and greater tissue heterogeneity predicted favorable outcomes in patients with large ischemic core, indicating that tissue composition within the ischemic core, beyond its volume, is associated with functional outcome after reperfusion. Among large-core patients who achieved successful reperfusion, ADC-based tissue characterization may help predict functional outcome.