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

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Radiology

Background:

• Sequential coronary CT angiography (CCTA) is susceptible to step artifacts, hindering plaque visualization and automated analysis like CT-fractional flow reserve.
• These artifacts arise from image acquisition across different heartbeats, creating discontinuities in coronary segments.

Purpose of the Study:

• To evaluate a step artifact reduction (SAR) algorithm, alone and with motion-compensated reconstruction (MCR), for improving image quality in sequential CCTA.
• To quantify the impact of SAR and SAR+MCR on lumen continuity and reduce step-related artifacts.

Main Methods:

• Retrospective analysis of 79 patients undergoing sequential CCTA on a 128-slice dual-layer spectral CT system.
• Comparison of three reconstruction methods: clinical standard, SAR, and SAR+MCR.
• Quantification of lumen continuity using Jaccard index (JI) for coronary segments and histogram entropy for whole-heart continuity.

Main Results:

• SAR significantly increased mean Jaccard index (JI) across 165 coronary segments (0.38 to 0.58, P <0.01, d=0.84), improving lumen continuity.
• Histogram entropy decreased with SAR (3.81 to 3.51, P <0.01, d=-3.12), indicating fewer step-related structures.
• In motion-affected segments, SAR+MCR achieved higher JI (0.70) compared to SAR alone (0.49, P <0.01, d=0.89).

Conclusions:

• SAR effectively improves vessel and whole-heart continuity in sequential CCTA images acquired on dual-layer spectral CT.
• The addition of MCR provides further significant benefits for image quality in motion-affected coronary segments.
• These algorithmic improvements hold promise for enhanced plaque assessment and automated analysis in CCTA.