Effect of a motion-correction algorithm on motion-related image quality in mid-diastolic CCTA using 320-detector row CT.

BACKGROUND: Motion artifacts limit coronary CT angiography (CCTA) when mid-diastolic quiescence is short. RR-PQ estimates the low-motion interval available for reconstruction, whereas motion correction may improve image quality without changing cardiac physiology. PURPOSE: To primarily evaluate the incremental effect of Clear Motion Cardiac (CMC) compared with half-scan reconstruction and secondarily characterize the probability of diagnostic image quality across RR-PQ values and derive candidate operational RR-PQ values on a 0.24-s/rotation 320-detector row CT system. METHODS: In 1012 consecutive CCTA examinations, paired half-scan and CMC series were reconstructed from identical raw data. Motion was graded A-D (A/B diagnostic). McNemar tests compared paired rates; logistic models estimated diagnostic probability and candidate RR-PQ values. RESULTS: Diagnostic image quality increased from 841/1012 (83.1%) with half-scan to 939/1012 (92.8%) with CMC (p < 0.0001). Of 171 half-scan failures, 101 were rescued; degradation occurred in 3/1012. Benefit increased with heart rate and was greatest at ≥70 bpm. RR-PQ was strongly associated with the probability of diagnostic image quality; candidate values at 95% probability were 807 ms for half-scan and 739 ms for CMC. CONCLUSION: CMC improved diagnostic image quality, especially at higher heart rates and shorter RR-PQ. The derived values may aid workflow planning but are platform- and cohort-specific.