ASPECTS estimation using dual-energy CTA-derived virtual non-contrast in large vessel occlusion acute ischemic stroke: a dose reduction opportunity for patients undergoing repeat CT?

Abstract

Recent studies have shown the feasibility of dual-energy CT (DECT) virtual non-contrast (VNC) for determining infarct extent. In this study, patients presenting with large-vessel occlusion (LVO) acute ischemic stroke (AIS), we assess whether ASPECTS on DECTA-VNC differs from non-contrast CT (NCCT). After IRB approval, LVO-AIS patients undergoing NCCT and DECTA between October 2016 and September 2018 were retrospectively reviewed. DECTA-VNC images were derived using Syngo.via (Siemens, Erlangen, Germany). ASPECTS was scored by two blinded neuroradiologists. Square-weighted kappa statistic, diagnostic performance, Wilcoxon signed-rank tests between groups, and CT doses were calculated. Fifty-one patients met inclusion criteria, with median age of 76 (IQR 67–82); 26/51 (51%) were female. Median time between last-known-well and CT was 120 min (IQR 60–252). DECTA-VNC ASPECTS score differed by\u2009≤\u20091 from consensus NCCT in 49/51 (96%) patients for reader 1 and in 46/51 (90%) for reader 2. ASPECTS on DECTA-SI and consensus NCCT differed by\u2009≤\u20091 in 45/51 (88%) for both readers. On a per ASPECTS-region basis, DECTA-VNC had 87% sensitivity, 95% specificity, 0.82% PPV, and 0.96% NPV. ASPECTS inter-rater agreement was highest for DECTA-VNC (κ\u2009=\u20090.71), DECTA-SI (κ\u2009=\u20090.48), and NCCT (κ\u2009=\u20090.40). NCCT median CTDIvol was 63.7 mGy (IQR 60.7–67.2); DLP was 1060.0 mGy·cm (IQR 981.0–1151.5). DECTA-VNC dose was lower: median CTDIvol was 20.9 mGy (IQR 19.8–22.2); DLP was 804.1 (IQR 691.6–869.4), p\u2009<\u20090.0001. DECTA-derived VNC yielded similar ASPECTS scores as NCCT and is therefore non-inferior in early ischemia-related low attenuation edema/infarct detection in acute LVO-AIS patients. Further evaluation of the role of DECTA-VNC in AIS imaging is warranted.