[Impact of Hybrid Iterative Reconstruction Combined with a Sharpening Filter on Coronary Artery Stent Profile Characteristics and Visual Assessment in Coronary CT Angiography: A Phantom Study].

PURPOSE: In coronary CT angiography, we compared the profile characteristics and visual assessment of coronary stents between hybrid iterative reconstruction combined with a sharpening filter (S-HIR) and deep learning reconstruction (DLR).

METHODS

We scanned a performance evaluation phantom and a custom-made phantom incorporating a coronary artery stent with an inner diameter of 3.5 mm. Images were reconstructed using DLR, hybrid iterative reconstruction (HIR), and S-HIR of three sharpening strengths. We evaluated task-based transfer function (TTF) values, the maximum CT number of the stent struts, the error rate of the stent lumen diameter, rectangularity, and visual assessment performed by nine radiological technologists using Scheffé's paired comparison method.

RESULTS

In S-HIR, TTF values and rectangularity increased, while the error rate decreased with increasing sharpening strength. Visual assessment revealed no significant difference between sharpening medium filter+HIR (SM-HIR) and DLR. In contrast, sharpening high filter+HIR (SH-HIR) resulted in an excessive increase in the maximum CT number of the stent struts, and visual assessment scores decreased.

CONCLUSION

The S-HIR method newly proposed in this study altered the profile characteristics of coronary artery stents and improved their visibility in coronary CT angiography under phantom conditions. In particular, SM-HIR showed no statistically significant difference from DLR in visual assessment and could serve as a useful technique for improving coronary stent visibility in CT systems without DLR.