Automated determination of cardiac rest period on whole-heart coronary magnetic resonance angiography by extracting high-speed motion of coronary arteries

Purpose: The aim of the present study was to develop an automated system for determining the cardiac rest period during whole-heart coronary magnetic resonance angiography (CMRA) examination.

Materials and methods: Ten healthy male volunteers (25-51 years old, 50-77 beats/min heart rate) were enrolled in this prospective study. A motion area map was generated from a cine image set by extracting high-speed component of cardiac motion, and it was used to specify the rest period in the proposed CMRA. In conventional CMRA, the rest period was determined based on the visual inspection of cine images. Agreement of the start time, end time, and trigger time between the two methods was assessed by the Bland-Altman plot analysis. Two observers visually evaluated the quality of the curved planar reformation (CPR) image of the coronary arteries.

Results: The proposed method significantly prolonged the start time (mean systematic difference 37.7 ms, P < 0.05) compared with the conventional method. Good agreement was observed for the end time (mean systematic difference 8.9 ms) and trigger time (mean systematic difference -28.8 ms) between the two methods. A significantly higher image quality (P < 0.05) was provided for the left circumflex artery in the proposed CMRA (mean grading score 3.88) than in conventional CMRA (mean grading score 3.68).

Conclusion: Our system enabled detection of the rest period automatically without operator intervention and demonstrated somewhat higher image quality compared with conventional CMRA. Its use may be useful to improve the imaging workflow for CMRA in clinical practice.