This study aimed to determine whether brain imaging can identify patients who are most likely to benefit from endovascular thrombectomy for acute ischemic stroke, and whether such treatment improves clinical outcomes. Patients within 8 hours of onset of large-vessel, anterior-circulation strokes were randomly assigned to mechanical embolectomy (Merci Retriever or Penumbra System) or standard care. All patients underwent pretreatment brain imaging to assess the presence of a favorable penumbral pattern (substantial salvageable tissue and small infarct core) or a non-penumbral pattern (large core or small or absent penumbra). The primary outcome was assessed using the 90-day modified Rankin scale, which ranges from 0 (no symptoms) to 6 (dead). The study found no significant interaction between the pretreatment imaging pattern and treatment assignment, with no difference in outcomes between embolectomy and standard care. The rate of all-cause 90-day mortality was 21%, and the rate of symptomatic hemorrhage was 4%, with no significant differences across groups. The study concluded that a favorable penumbral pattern on neuroimaging did not identify patients who would benefit more from endovascular therapy, and embolectomy was not superior to standard care.This study aimed to determine whether brain imaging can identify patients who are most likely to benefit from endovascular thrombectomy for acute ischemic stroke, and whether such treatment improves clinical outcomes. Patients within 8 hours of onset of large-vessel, anterior-circulation strokes were randomly assigned to mechanical embolectomy (Merci Retriever or Penumbra System) or standard care. All patients underwent pretreatment brain imaging to assess the presence of a favorable penumbral pattern (substantial salvageable tissue and small infarct core) or a non-penumbral pattern (large core or small or absent penumbra). The primary outcome was assessed using the 90-day modified Rankin scale, which ranges from 0 (no symptoms) to 6 (dead). The study found no significant interaction between the pretreatment imaging pattern and treatment assignment, with no difference in outcomes between embolectomy and standard care. The rate of all-cause 90-day mortality was 21%, and the rate of symptomatic hemorrhage was 4%, with no significant differences across groups. The study concluded that a favorable penumbral pattern on neuroimaging did not identify patients who would benefit more from endovascular therapy, and embolectomy was not superior to standard care.