The MR RESCUE trial evaluated whether brain imaging could identify patients most likely to benefit from endovascular treatment for acute ischemic stroke and whether mechanical embolectomy improved clinical outcomes. The study randomly assigned 118 patients with large-vessel, anterior-circulation strokes within 8 hours of symptom onset to either mechanical embolectomy (Merci Retriever or Penumbra System) or standard care. All patients underwent pretreatment CT or MRI to assess penumbral patterns, defined as favorable (substantial salvageable tissue and small infarct core) or non-penumbral (large core or small/absent penumbra). The primary outcome was the 90-day modified Rankin scale (0-6), measuring functional disability. Results showed no significant difference in outcomes between the embolectomy and standard care groups. Patients with favorable penumbral patterns had similar outcomes to those with non-penumbral patterns, and embolectomy was not superior to standard care. No interaction between imaging pattern and treatment assignment was found. Safety outcomes included 21% 90-day mortality and 4% symptomatic intracranial hemorrhage, with no significant differences between groups. Revascularization was achieved in 67% of embolectomy patients, but outcomes were not improved. The study found no evidence that penumbral imaging selection improved clinical outcomes. The trial highlights the limitations of current imaging techniques in identifying patients who would benefit from endovascular therapy. While endovascular treatment may be effective in some cases, it does not consistently improve outcomes compared to standard care. The study also notes that the use of newer-generation devices may yield better results, but the current findings do not support the efficacy of first-generation devices. The results suggest that imaging-based selection may not be a reliable predictor of treatment benefit, and further research is needed to evaluate the effectiveness of newer devices and imaging techniques.The MR RESCUE trial evaluated whether brain imaging could identify patients most likely to benefit from endovascular treatment for acute ischemic stroke and whether mechanical embolectomy improved clinical outcomes. The study randomly assigned 118 patients with large-vessel, anterior-circulation strokes within 8 hours of symptom onset to either mechanical embolectomy (Merci Retriever or Penumbra System) or standard care. All patients underwent pretreatment CT or MRI to assess penumbral patterns, defined as favorable (substantial salvageable tissue and small infarct core) or non-penumbral (large core or small/absent penumbra). The primary outcome was the 90-day modified Rankin scale (0-6), measuring functional disability. Results showed no significant difference in outcomes between the embolectomy and standard care groups. Patients with favorable penumbral patterns had similar outcomes to those with non-penumbral patterns, and embolectomy was not superior to standard care. No interaction between imaging pattern and treatment assignment was found. Safety outcomes included 21% 90-day mortality and 4% symptomatic intracranial hemorrhage, with no significant differences between groups. Revascularization was achieved in 67% of embolectomy patients, but outcomes were not improved. The study found no evidence that penumbral imaging selection improved clinical outcomes. The trial highlights the limitations of current imaging techniques in identifying patients who would benefit from endovascular therapy. While endovascular treatment may be effective in some cases, it does not consistently improve outcomes compared to standard care. The study also notes that the use of newer-generation devices may yield better results, but the current findings do not support the efficacy of first-generation devices. The results suggest that imaging-based selection may not be a reliable predictor of treatment benefit, and further research is needed to evaluate the effectiveness of newer devices and imaging techniques.