Is limited-coverage CT perfusion helpful in treatment decision-making in patients with acute ischemic stroke?

Background: The initial core infarct volume predicts treatment outcome in patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO). According to the literature, CT perfusion (CTP) is able to evaluate cerebral parenchymal viability and assess the initial core in AIS. We prospectively studied whether limited-coverage CTP with automated core calculation correlates with the final infarct volume on follow-up non-enhanced CT (NECT) in patients successfully treated by mechanical thrombectomy. Methods: We enrolled 31 stroke patients (20 women aged 74.4 +/- 12.9 years and 11 men aged 66 +/- 15.4 years; median initial NIHSS score 15.5) with occlusion of the medial cerebral artery and/or the internal carotid artery that were treated by successful mechanical thrombectomy. CTP performed in a 38.6 mm slab at the level of basal ganglia was included in the CT stroke protocol, but was not used to determine indication for mechanical thrombectomy. The infarction core volume based on CTP was automatically calculated using dedicated software with a threshold defined as cerebral blood flow <30% of the value in the contralateral healthy hemisphere. The final infarction volume was measured on 24-hour follow-up NECT in the same slab with respect to CTP. Pearson and Spearman correlation coefficients and robust linear regression were used for comparison of both volumes, P values <0.05 were considered as statistically significant. Results: The median time from stroke onset to CT was 77 minutes (range, 31-284 minutes), and the median time from CT to vessel recanalization was 95 minutes (range, 55-215 minutes). The mean CTPcalculated core infarct volume was 24.3 +/- 19.2 mL (median 19 mL, range 1-79 mL), while the mean final infarct volume was 21.5 +/- 39.5 mL (median 8 mL; range 0-210 mL). Only a weak relationship was found between the CTP-calculated core and final infarct volume [Pr(29) =0.32, P=0.078; rho =0.40, P=0.028]. Regression analysis showed CTP significantly overestimated lower volumes. Conclusions: In our prospective study, the infarction core calculated using limited-coverage CTP only weakly correlated with the final infarction volume measured on 24-hour follow-up NECT; moreover, CTP significantly overestimated lower volumes. Our results do not support the use of limited-coverage CTP for guiding treatment recommendations in patients with AIS.