Improved Visualization of Coronary Arteries Using a New Three-Dimensional Submillimeter MR Coronary Angiography Sequence with Balanced Gradients

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Abstract
OBJECTIVE. The goal of our study was to evaluate a new three-dimensional real-time navigator MR coronary angiography sequence to noninvasively visualize the coronary arteries. SUBJECTS AND METHODS. Fifteen healthy volunteers underwent MR coronary angiography with a new balanced turbo field-echo sequence in comparison with the standard turbo field-echo sequence. Signal-to-noise, blood-to-myocardium, blood-to-fat, and blood-to-pericardial fluid contrast ratios of the left and right coronary artery systems were measured. Image quality was graded, the length and diameter of the coronary arteries were measured, and the number of visible side branches was assessed. RESULTS. The balanced turbo field-echo images yielded a higher blood-to-myocardium and blood-to-pericardial fluid contrast ratio, a similar blood-to-fat contrast ratio, and a lower signal-to-noise ratio than the turbo field-echo images. On a 5-point grading scale (1, nondiagnostic or unreadable; 2, poor; 3, moderate; 4, good; 5, excellent), image quality was rated significantly better for the balanced turbo field-echo sequence than for the turbo field-echo sequence (left coronary artery, 4.0 ± 0.6 vs 3.6 ± 0.5 [p = 0.015]; right coronary artery, 4.4 ± 0.4 vs 3.6 ± 0.4 [p < 0.0001], respectively), resulting in a significantly longer segment of the three major coronary arteries visualized (left anterior descending coronary artery, 92 ± 21 mm vs 79 ± 24 mm; left circumflex coronary artery, 70 ± 7 mm vs 60 ± 18 mm; right coronary artery, 112 ± 28 mm vs 95 ± 27 mm) and a significantly higher number of side branches visualized (left anterior descending coronary artery, 2.9 ± 1.3 vs 1.5 ± 1.3; left circumflex coronary artery, 2.1 ± 1.7 vs 1.0 ± 1.2; right coronary artery, 3.7 ± 1.7 vs 2.6 ± 1.5). Mean imaging time per coronary artery was significantly shorter for the balanced turbo field-echo sequence (5.7 ± 1.0 min) than for the turbo field-echo sequence (8.4 ± 1.4 min) (p < 0.0001). CONCLUSION. Compared with standard turbo field-echo MR coronary angiography, optimized balanced turbo field-echo MR coronary angiography improves the visualization of the coronary arteries and their side branches within a significantly shorter imaging time.