Three-dimensional heart locator and compressed sensing for whole-heart MR angiography

Abstract

Purpose We sought to develop a whole-heart magnetic resonance angiography technique with three-dimensional (3D) respiratory motion compensation and reduced scan time. Methods A novel respiratory motion compensation method was implemented that acquires a 1D navigator (NAV) and a low-resolution 3D-image of the heart (3D-LOC) just before the angiography data. The central 10% of SSFP k-space was fully acquired using NAV-gating, and then 10% of peripheral k-space was randomly undersampled to complete the scan. Spatial registration of the 3D-LOC information was used to correct the central and peripheral k-space lines for the bulk respiratory motion in three dimensions, and then the remaining k-space data was estimated using compressed sensing (CS). Ten volunteers each underwent two angiography acquisitions with 1 mm3 resolution: (i) conventional NAV with CS, and (ii) the new 3D-LOC with CS. Results Compared with conventional NAV, the new 3D-LOC with CS technique had a shorter scan time (4.8 ± 1.1 versus 6.3 ± 1.7 min; P < 0.001), better objective vessel sharpness for all three coronary arteries (P < 0.05), and no difference in subjective vessel sharpness for all three coronary arteries. Conclusion Compared with conventional NAV with CS, acceleration and respiratory motion correction using 3D-LOC with CS reduces scan time and improves objective vessel sharpness.