Navigator echo-based respiratory gating for three-dimensional MR coronary angiography: Results from healthy volunteers and patients with proximal coronary artery stenoses

OBJECTIVE. The purpose of our study was to investigate the value of respira tory-gated three-dimensional (3D) MR angiography in identifying coronary ar teries in healthy volunteers and in patients with proximal coronary artery stenosis and to compare the results with those of conventional coronary ang iography. SUBJECTS AND METHODS. Twenty healthy volunteers and 20 patients with corona ry artery stenosis were examined on a 1.5-T scanner with a retrospectively respiratory-gated 3D gradient-echo sequence. Visualization of the main coro nary arteries was analyzed after curved multiplanar reconstructions. A six- point grading system was used to evaluate 400 vessel segments. The assessme nt of stenosis was performed by two observers who were unaware of the resul ts of conventional coronary angiography. RESULTS. The proximal, middle, and distal segments of the coronary arteries were completely identified with or without luminal irregularities in 55%, 47%, and 20%, respectively, of the healthy volunteers. For the 20 patients, results were 69%, 44%, and 20%, respectively. For the assessment of corona ry artery stenoses (n = 53), sensitivity was 73% and specificity was 50% af ter evaluation of the MR angiograms of all patients. A sensitivity of 79% a nd a specificity of 54% were found for evaluation of the MR coronary angiog rams, with an image quality score of at least 3 (i.e., artery segments comp letely identified with major luminal irregularities). CONCLUSION. With the navigator echo MR imaging technique, a complete 3D vis ualization of the main coronary arteries was possible in cases with high im age quality. However, further experience with and improvement of the naviga tor echo technique we used is necessary for reliable assessment of coronary artery stenosis.