Abstract
To investigate the accuracy of a dual-projection respiratory self-gating (DP-RSG) technique in dynamic heart position measurement and its feasibility for free-breathing whole-heart coronary MR angiography (MRA). A DP-RSG method is proposed to enable accurate direct measurement of heart position by acquiring two whole-heart projections. On 14 volunteers we quantitatively evaluated the efficacy of DP-RSG by comparison with diaphragmatic navigator (NAV) and single-projection-based respiratory self-gating (SP-RSG) methods. For DP-RSG we also compared center-of-mass and two profile-matching algorithms in deriving heart motion. Coronary imaging was conducted on eight volunteers based on retrospective gating to preliminarily validate the effectiveness of DP-RSG for whole-heart coronary MRA. Comparison of vessel delineation was performed between images reconstructed using different gating methods. The quantitative evaluation shows that DP-RSG more accurately tracks heart motion than NAV with all gating window (GW) values and SP-RSG approaches with GW>or=2.5 mm and profile-matching algorithms are more reliable for motion derivation than center-of-mass calculations with GW>or=1.0 mm. Whole-heart coronary MRA studies demonstrate the feasibility of using DP-RSG to improve overall delineation of the coronary arteries. DP-RSG is a promising approach to better resolve respiratory motion for whole-heart coronary MRA compared to conventional NAV and SP-RSG.
Highlights
Coronary MR angiography (MRA) is emerging as an noninvasive technique for diagnosis of coronary artery diseases
dual-projection respiratory self-gating (DP-respiratory self-gating (RSG)) is a promising approach to better resolve respiratory motion for wholeheart coronary MRA compared to conventional NAV and single-projection-based respiratory self-gating (SP-RSG)
The heart profile is better depicted in the DP-RSG projection with sharper upper and lower edges compared to the SP-RSG projection with superimposed chest wall signals obscuring the heart profile
Summary
Coronary MR angiography (MRA) is emerging as an noninvasive technique for diagnosis of coronary artery diseases. Coronary MRA is performed using double-oblique thin slabs targeted at specific coronary artery branches and requires precise planning of the imaging plane for each coronary artery branch on each subject [1,2,3]. Due to the tortuous geometry of coronary arteries, visualization is highly dependent on operator skills and restricted by the slab thickness. The complete coronary artery tree is covered in a single measurement and individual branches can be visualized by reformatting the three-dimensional data set retrospectively. Wholeheart scans require multifold increases in imaging time compared to volume-targeted scans. Despite recent significant advances in MRA, e.g. fast pulse sequences and parallel imaging, the imaging time for high-quality whole-heart coronary MRA is still far beyond breath-hold capabilities and necessitates data acquisition during free-breathing
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