MRI Metabolic Biomarkers Predict Ischemic Lesion Survival in Hyperacute Stroke: New Insight on Diffusion Reversibility.

Abstract

Background In patients with acute ischemic stroke (AIS), ischemic core volume overestimation at diffusion-weighted MRI due to diffusion reversal has been described following successful reperfusion. Purpose To assess the potential role of the oxygen extraction fraction (OEF), derived from baseline dynamic susceptibility contrast (DSC) MRI, in diffusion reversal prediction in patients with AIS after successful reperfusion. Materials and Methods This retrospective study (January 2015 to December 2020) included patients with anterior-circulation large-vessel occlusion stroke who underwent pretreatment MRI, including diffusion-weighted imaging and DSC perfusion, achieved successful reperfusion (modified Thrombolysis in Cerebral Infarction score ≥2c), and underwent follow-up MRI within 48 hours. Ischemic core masks were generated from baseline MRI using an apparent diffusion coefficient (ADC) threshold of 620 × 10^-6 mm²/sec or less, and infarct masks were generated from the final DWI scans. DSC perfusion was used to calculate the relative OEF (rOEF). Image co-registration and subtraction were performed to determine the final voxel fate as persistent infarct versus surviving tissue. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed to assess imaging biomarker predictive value. Results Seventy patients were included (mean age, 72.2 years ± 13.1 [SD]; 40 female). Approximately 35% of the volume initially designated as the ischemic core showed diffusion reversal. Following logistic regression, the independent imaging variables associated with reducing the odds that ischemic core voxels would evolve to infarct voxels were ADC (odds ratio [OR], 0.99; 95% CI: 0.94, 1.0; P < .001) and rOEF (OR, 0.33; 95% CI: 0.32, 0.35; P < .001). A combined ADC plus rOEF model showed an area under the ROC curve (AUC) of 0.80 (95% CI: 0.80, 0.81), sensitivity of 74%, and specificity of 76% for infarct prediction, outperforming ADC alone (AUC, 0.65 [95% CI: 0.64, 0.66], sensitivity, 60%; specificity, 63%; P < .001). The added value of rOEF in delineating ischemic core was time-dependent, with the strongest negative impact within 120 minutes from stroke onset. Conclusion In patients with AIS for whom reperfusion was successful, the addition of rOEF to ADC improved ischemic core definition by predicting diffusion reversal and reducing core volume overestimation, especially in the hyperacute window. © RSNA, 2026 Supplemental material is available for this article. See also the editorial by Rapalino in this issue.