Objective Assessment of a Step Artifact Correction Algorithm in Sequential Coronary CT Angiography on Dual-Layer CT

Prospectively ECG-triggered sequential coronary CT angiography (CCTA) is prone to step artifacts between cardiac segments imaged during different heartbeats, which can obscure plaque and impair automated tools such as CT-fractional flow reserve. We evaluated a vendor-specific step artifact reduction (SAR) algorithm, alone and combined with motion-compensated reconstruction (MCR), in sequential CCTA. We retrospectively analyzed 79 patients scanned on a 128-slice dual-layer spectral CT system. Reconstructions compared were clinical standard, SAR, and SAR+MCR. Lumen continuity across the step interface in the left anterior descending (LAD) and right coronary arteries (RCA) was quantified by the Jaccard index (JI), and whole-heart continuity by histogram entropy of subtraction images; Cohen d is reported for effect sizes. Across 165 coronary step segments, SAR increased mean JI from 0.38 to 0.58 (+0.20; 95% CI: 0.16-0.23; P<0.01; d=0.84), similar in both vessels (LAD +0.20, d=0.82; RCA +0.19, d=0.87). Entropy decreased from 3.81 to 3.51 (-0.30; P<0.01; d=-3.12), indicating fewer step-related structures. In 25 motion-affected RCA segments, SAR alone increased the JI from 0.35 to 0.49, and adding MCR raised it to 0.70 (+0.22 vs. SAR alone; P<0.01; d=0.89). SAR improved vessel and whole-heart continuity on dual-layer spectral CT, with additional benefit from MCR in motion-affected segments.