ABSTRACT NUMBER: ESOC2026A1879 OXYGEN EXTRACTION FRACTION IMAGING AFTER ENDOVASCULAR TREATMENT CORRELATES WITH HYPOPERFUSION AND FUNCTIONAL OUTCOME IN LVO-ACUTE ISCHEMIC STROKE

Abstract Background and aims The persistence of hypoperfusion areas in the brain on perfusion-weighted MRI is associated with functional outcome after endovascular treatment for large-vessel ischemic stroke. This study aimed to assess the value of measuring Oxygen Extraction Fraction (OEF) imaging after thrombectomy by evaluating its relationship with clinical outcome and hypoperfusion. Methods Single-center patients from the CHOICE trial assessing the value of post-thrombectomy IA rTPA in patients with large-vessel ischemic stroke who underwent successful endovascular treatment and had perfusion-weighted MRI within 48 hours were included (n=22). OEF and TMAX maps were derived from dynamic susceptibility contrast (DSC-MRI). Lesion ROIs defined on DSC-MRI were applied to extract OEF values and quantify hypoperfusion volume (Tmax>6s). Volumes of tissue with elevated OEF were computed across intensity thresholds (0.00–1.00, step0.05). Associations with 90-day modified Rankin Scale (mRS) were assessed using Spearman correlation. ROC analysis evaluated the prediction of poor outcome (mRS 3–6). Results An OEF cutoff of >0.80 showed the strongest association with functional outcome among the tested OEF thresholds. The volume of tissue with OEF >0.80 was strongly correlated with hypoperfusion volume (Spearman’s ρ = 0.89, p <0.001). Both metrics demonstrated excellent discrimination for poor 90-day outcome, with an AUC of 0.91 for OEF >0.80 and 0.86 for Tmax>6s (non-significant difference, Figure 1). Conclusions Elevated OEF identifies metabolically compromised tissue that closely corresponds to severe hypoperfusion and shows comparable prognostic performance for functional outcome. Conflict of interest Andrea Cabero-Arnold: nothing to disclose Figure 1 - belongs to Results