Effect of ZeeFree algorithm on the reduction of stair-step artifacts for coronary computed tomography angiography

Stair-step artifacts is a common type of artifacts in the sequential scanning of CCTA and severely affects the image quality of coronary artery scans. This study aims to evaluate a novel algorithm for the removal of stair-step artifacts. 95 patients (52 males and 43 females, average weight of 70.81 ± 11.68 kg, median height of 1.66 [1.72, 1.6], average BMI of 25.57 ± 3.09 kg/m²) who received CCTA scanning on the new generation of dual source CT scanner, SOMATOM Pro.Pulse, were prospectively enrolled for the study. Images were reconstructed with or without ZeeFree to compare the effect of this novel algorithm. The doctors were asked to evaluate the severity of stair-step artifacts, image quality and diagnostic confidence with a 5-Likert scale. The subjective scoring comparison was performed Chi-square test in Python 3.11.10. Subgroups were divided by heartbeat and BMI and the same comparison was performed to evaluate the performance of ZeeFree with different factors. Additionally, a preliminary assessment of the degree of luminal stenosis was conducted and compared with the ICA. There was no significant difference for patients' basic information between subgroups, except for the weight, contrast medium and radiation dose when divided by BMI. 76.8% (86/112) of the stair-step artifacts were resolved with ZeeFree algorithm. For the subjective scoring results, ZeeFree algorithm always shows a significant improvement for the severity of stair-step artifacts, image quality and diagnostic confidence (all p < 0.001). The differences stay significant for subgroup analysis. The Cohen' s Kappa value of the ZeeFree reconstruction with ICA was 0.85, which demonstrated a great consistency in stenosis assessment. ZeeFree algorithm could significantly reduce the occurrence of stair-step artifacts, enhance the quality of coronary artery images and diagnostic usability.