Assessment of computed tomography perfusion RAPID estimated core volume accuracy in patients following thrombectomy

Background: Computed Tomography Perfusion (CTP) maps ischemic core volume (CV) and penumbra following a stroke; however, its accuracy in early symptom onset is not well studied. We compared the accuracy of CTP RAPID estimated CV with diffusion weighted imaging (DWI) infarct volume (IV) in patients following thrombectomy. Methods: Charts of anterior circulation large vessel occlusion post-thrombectomy cases with thrombolysis in cerebral infarction (TICI) 2b/3 reperfusion from 2017 to 2019 were reviewed. CTP time was dichotomized as 0-3 hours and ≥ 3 hours from the last known normal (LKN) cognition. The volumetric difference (VD), defined as DWI IV minus CTP CV, core volume overestimation (CVO), defined as CTP CV minus DWI IV and Alberta stroke programme early CT score (ASPECTS) were calculated. Large CV was defined as ≥ 50 ml CV. Modified Rankin Score (mRS) at 90 days were reviewed. We performed independent sample t-test and Spearman correlation coefficient test. Results: Total cases (n) were 61. In < 3 hours window from LKN (n = 27), the mean VD was 58.3 ± 0.1 ml (P = 0.990) and CVO (n = 11; 40.7%) was 39.6 ± 35.7 ml (P = 0.008). Mean large CV (n = 8) was 78.3 ± 25.4 ml with median ASPECTS of 8 [interquartile range (IQR) = 6.5-9.0] and median mRS at 90 days of 2 (IQR = 0.8-3.3). In ≥ 3 hours window from LKN (n = 34), CVO (n = 5) was uncommon and large CV had median mRS at 90 days of 5 (IQR = 4.0-6.0). Conclusion: CTP more frequently overestimates CV in patients who are < 3 hours from LKN. The treated patients with large CV in < 3 hours and > 3 hours had good and poor functional outcomes, respectively.