Evaluation of three-dimensional, navigator-gated whole heart MR coronary angiography: the importance of systolic imaging in subjects with high heart rates

Purpose To evaluate the influence of heart rate (HR) on magnetic resonance coronary angiography (MRCA) image quality in diastolic and systolic phases. Materials and methods Twenty-seven healthy volunteers (9 men; 33±9 years, HR 53–110 bpm), were evaluated with the electrocardiography and three-dimensional, navigator-gating MRCA in a 1.5-T MR scanner (Avanto, Siemens) in diastolic and systolic phases (steady-state free precession; TR/TE/flip angle=3.2 ms/1.6 ms/90°). The timing of scanning was individually adapted to the cardiac rest periods obtained in the prescanning by visually identifying when the movement of right coronary artery was minimized during diastole and systole. Images of two phases were compared side by side on a 4-point scale (from 1=poor to 4=excellent visibility; score of 3 or 4 as diagnostic). Results Of 13 subjects with HR ≤65 bpm (low HR group, mean 59.8±4.9 bpm, range 53–65), the image quality scores were significantly better than that with higher heart rates (73.9±9.0 bpm, range 68–110) in diastolic MRCA. The image quality was significantly improved during systole in high HR group. Overall, 91.3% of low HR group had MRCA image of diagnostic quality acquired at diastole, while 88.3% of high HR group had diagnostic images at systole by segmental analysis (P=nonsignificant). Conclusions MRCA at systole offered superior quality in patients with high heart rates.