Abstract WP63: Computed Tomography Perfusion in Stroke Mimics

Abstract

Background: Automated computed tomography perfusion (CTP) can help select acute ischemic stroke patients for thrombectomy. The prevalence and patterns of abnormal findings on automated CTP in patients with stroke mimic has not been well characterized. Hypothesis: Normal perfusion (time-to-tissue maximum, T max >6s) or a perfusion pattern that is discordant with a patient’s clinical symptoms or vessel imaging results will be predictive of a stroke mimic diagnosis. Methods: We reviewed a retrospective multi-site consecutive cohort of patients undergoing CTP for suspected acute ischemic stroke ≤24 hours from onset (6/2017-12/2017). The primary outcome was the incidence of any T max >6s abnormality on RAPID automated perfusion-weighted CT imaging comparing patients with stroke/TIA to those with stroke mimic. The presence of perfusion abnormalities that were discordant with clinical symptoms and CTA findings was also assessed. Results: Of 410 consecutive patients who underwent CTP, 348 met inclusion criteria (51.2% stroke, 5.5% TIA, and 43.4% mimic). The median NIHSS at presentation was 8 (IQR 4-15) and was slightly worse among stroke/TIA patients (9 vs. 7, p=0.057). The median time from LKN to CTP acquisition for all patients was 302 minutes (IQR 158-707) and was no different between groups (p=0.148). T max abnormalities were seen in 27.8% of patients with stroke mimic and 61.9% of patients with stroke/TIA (p<0.001). Stroke mimics were more likely to have a normal T max pattern (volume=0mL; adjusted OR 4.01, 95%CI 2.34-6.87, p<0.001). Mimics were more likely to have T max patterns discordant with clinical symptoms and CTA findings than patients with stroke/TIA (91.3% vs. 28.2%, p<0.001). Patients with only discordant T max abnormalities were more likely to have a stroke mimic (adjusted OR 30.05, 95%CI 5.27-171.39, p<0.001), with a positive predictive value for identifying mimic of 90.5% (85.2-94.1%). Conclusion: While one-quarter of patients with stroke mimic show abnormalities on automated CTP maps using RAPID, the vast majority of patterns were discordant with symptoms and vessel status. Normal or only discordant T max abnormalities are strongly associated with stroke mimics and may inform stroke treatment decision making.