Background Patient selection for acute ischemic stroke has been largely driven by time-based criteria, although emerging data suggest that image-based criteria may be useful. The purpose of this study was to directly compare outcomes of patients treated within a traditional time window with those treated beyond this benchmark when CT perfusion (CTP) imaging was used as the primary selection tool. Methods A prospectively collected database of all patients with acute ischemic stroke who received intraarterial therapy at the Medical University of South Carolina was retrospectively analyzed, regardless of time from symptom onset. At presentation, CTP maps were qualitatively assessed. Selected patients underwent intraarterial therapy. Functional outcome according to the modified Rankin scale (mRS) score at about 90 days was documented. Results 140 patients were included in the study. The median time from symptom onset to groin access was 7.0 h. Overall, 28 patients (20%) had bleeding complications, but only 10 (7.1%) were symptomatic. The average National Institute of Health Stroke Scale (NIHSS) score for patients treated ?7 h from symptom onset was 17.3 and 30.2% had a mRS score of 0-2 at 90 days. Patients treated >7 h from symptom onset had an average NIHSS score of 15.1 and 45.5% achieved a mRS score of 0-2 at 90 days ( p=0.104). Patients in the two groups had similar rates of symptomatic intracerebral hemorrhage (8.5% and 5.8%, respectively; p=0.745). Conclusions No difference was found in the rates of good functional outcome between patients treated ?7 h and those treated >7 h from symptom onset. These data suggest that imaging-based patient selection is a safe and viable methodology.