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Updated: Aug 19, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
MRI Metabolic Biomarkers Predict Ischemic Lesion Survival in Hyperacute Stroke: New Insight on Diffusion
Mona Asghariahmadabad1, Ameera Ismail2, Mana Shams2
1Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, Box 0628, San Francisco, CA 94143.
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.
Insights
In acute ischemic stroke (AIS) patients with successful reperfusion, oxygen extraction fraction (rOEF) combined with apparent diffusion coefficient (ADC) accurately predicts diffusion reversal, reducing overestimation of the ischemic core volume. This combined approach is especially valuable in the hyperacute stroke window.
Area of Science:
- Neuroradiology
- Stroke Imaging
- Cerebrovascular Disease
Background:
- Diffusion-weighted imaging (DWI) can overestimate ischemic core volume in acute ischemic stroke (AIS) following successful reperfusion due to diffusion reversal.
- Predicting this diffusion reversal is crucial for accurate stroke assessment and treatment planning.
Purpose of the Study:
- To evaluate the role of baseline oxygen extraction fraction (OEF), derived from dynamic susceptibility contrast (DSC) MRI, in predicting diffusion reversal in AIS patients after successful reperfusion.
- To assess if OEF improves the accuracy of ischemic core volume estimation compared to apparent diffusion coefficient (ADC) alone.
Main Methods:
- Retrospective analysis of 70 AIS patients with anterior circulation large-vessel occlusion and successful reperfusion.
- Baseline DWI and DSC perfusion MRI were used to calculate ADC and relative OEF (rOEF).
- Follow-up MRI within 48 hours assessed infarct evolution; logistic regression and ROC analysis determined predictive value.
Main Results:
- Approximately 35% of the initial diffusion-weighted imaging (DWI) defined ischemic core demonstrated diffusion reversal.
- Both ADC and rOEF independently predicted the evolution of ischemic core voxels to infarct.
- A combined ADC + rOEF model showed superior infarct prediction (AUC 0.80) compared to ADC alone (AUC 0.65), with 74% sensitivity and 76% specificity.
- The predictive value of rOEF was most significant within 120 minutes of stroke onset.
Conclusions:
- In AIS patients with successful reperfusion, incorporating rOEF with ADC enhances the definition of the ischemic core.
- This combined approach improves prediction of diffusion reversal, thereby reducing overestimation of infarct volume, particularly in the hyperacute phase.
- rOEF provides valuable prognostic information beyond ADC in acute stroke imaging.
