Diagnostic performance of single-phase CT angiography in detecting large vessel occlusion in ischemic stroke: A systematic review

Purpose: To systematically review the diagnostic performance of single-phase CT angiography (CTA) in detecting intracranial large vessel occlusion (LVO). Method: MEDLINE and Embase were searched for studies investigating the diagnostic performance of single-phase CTA in detecting LVO. Study quality was assessed. Sensitivity and specificity were calculated and meta-analyzed with a bivariate random-effects model. Heterogeneity was assessed with a chi-squared test. Results: Eleven studies were included. High risk of bias with regard to "patient selection", "reference standard", and "flow and timing" was present in 4, 1, and 2 studies, respectively. In 7 studies, it was unclear whether reference tests were interpreted blinded to CTA readings. There was variability in types of vessel segments analyzed, resulting in heterogeneous sensitivity and specificity (P < 0.05). Two studies provided data for the proximal anterior circulation (distal intracranial carotid artery, A1-, A2-, M1- and M2-segments), with pooled sensitivity of 88.4 % (95 % CI: 62.2-97.2 %) and pooled specificity of 98.5 % (95 % CI: 33.2-100 %). One study suggested that multiphase CTA improved agreement between nonexperts and an expert in detecting A1-, A2-, M1-, M2-, and M3-segment occlusions compared to single-phase CTA (kappa = 0.72-0.76 vs. kappa = 0.32-0.45). No other included study reported added value of advanced CTA (CT perfusion, 4D-CTA, or multiphase CTA) compared to single-phase CTA in detecting proximal anterior circulation LVO. Conclusion: There is lack of high-quality studies on the diagnostic performance of single-phase CTA for LVO detection in the proximal anterior circulation. The added value of advanced CTA techniques in detecting proximal anterior circulation LVO is not completely clear yet.