Coronary arteries: three-dimensional MR imaging with retrospective respiratory gating.

Abstract

Thin-section, three-dimensional (3D) gradient-echo magnetic resonance imaging of the coronary arteries was performed without and with retrospective respiratory gating in 12 healthy volunteers and one patient. In all examinations, results were improved with gating. In five of seven volunteer examinations, coronary artery delineation on images reconstructed by using the least-squares method for motion detection with navigator echoes was found to be equal to that obtained by using edge detection. Images in five other volunteers covered the entire heart with multiple overlapping 3D slabs. The arteries were segmented from the background and could be viewed from any orientation. The lengths of contiguously visible vessels were as follows: left main coronary artery, 11.5 mm +/- 0.4 (mean +/- standard deviation); left anterior descending branch, 115.9 mm +/- 19.7; left circumflex branch, 97.2 mm +/- 12.5; and right coronary artery, 125.9 mm +/- 18.8. This respiratory gating technique clearly improved depiction of the coronary arteries.

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

“…The gain is up to almost 21% compared with turbo field-echo imaging. Absolute measurements of the left coronary artery and right coronary artery yield superior values to most measurements reported in the literature [26,27] and are close to the coronary are artery lengths reported by Li et al [28]. As a result of the increased visualization of the coronary arteries in most volunteers, the right coronary artery was clearly visible in the inferior part of the right atrioventricular groove and in the proximal part of the inferior interventricular groove.…”

Magnetic Resonance Angiography

“…A summary of recent coronary MRA studies reporting on visualization of coronary arteries in healthy volunteers and patients with coronary artery disease is presented in Table 5. Both 2D 24,179 -182 and 3D 172,178,179,[183][184][185][186] approaches have been used at multiple centers with similar results. The origin and proximal coronary arteries are visualized in Ͼ95% of subjects.…”

Cardiac MR Assessment of Coronary Arteries

“…The introduction of respiratory navigators (MR signals that measure the position of the right lung-diaphragm interface) markedly improved image quality of freebreathing MRA. Respiratory navigator gating was initially performed in a retrospective fashion in which only images within a gating window were used to reconstruct coronary MRA [14][15][16][17]. This was replaced with real-time prospective navigation, where both navigator and coronary imaging data are acquired at the same time during the cardiac cycle [18,19].…”