Purpose: To assess the optimal timing for coronary magnetic resonance (MR) angiography in children with congenital heart disease by using dual cardiac phase whole-heart MR imaging.
Materials and methods: The local institutional review board approved this study, and informed consent was obtained from parents or guardians. Thirty children (13 girls; overall mean age, 5.01 years) were examined with a 1.5-T MR system. A free-breathing three-dimensional steady-state free precession dual cardiac phase sequence was used to obtain MR angiographic data during end-systolic and middiastolic rest periods. Vessel length, diameter, and sharpness, as well as image quality of the coronary artery segments, were analyzed and compared by using Bland-Altman plots, linear regression analysis, the t test, and Wilcoxon signed rank tests.
Results: Optimal coronary artery imaging timing was patient dependent and different for each coronary artery segment (36 segments favored end systole, 28 favored middiastole). In 15 patients (50%), different segments favored different cardiac phases within the same patient. Image quality and vessel sharpness degraded with higher heart rates, with a similar correlation for end systole (right coronary artery [RCA], 0.39; left main [LM] coronary artery, 0.46; left anterior descending [LAD] artery, 0.51; and left circumflex [LCX] artery, 0.50) and middiastole (RCA, 0.34; LM, 0.45; LAD, 0.48; and LCx, 0.55). Mean image quality difference or mean vessel sharpness difference showed no indication to prefer a specific cardiac phase.
Conclusion: The optimal cardiac rest period for coronary MR angiography in children with congenital heart disease is specific for each coronary artery segment. Dual cardiac phase whole-heart coronary MR angiography enables optimal coronary artery visualization by retrospectively choosing the optimal imaging rest period.