Fig. 1

Diagram showing the proposed electrocardiogram (ECG)-triggered free-breathing 3D T2-prepared balanced steady state free precession (bSFFP) sequence with a threefold undersampled variable-density Cartesian trajectory. 2D image-based navigators (iNAV)s are acquired at each cardiac cycle by spatially encoding the start-up echoes preceding the 3D cardiovascular magnetic resonance angiography (CMRA) acquisition to enable 100% scan efficiency and predictable scan time. Fat saturation and adiabatic T2 preparation pulses are used to improve signal homogeneity in the blood pool without using exogenous contrast agents (A). The iNAVs. are used to estimate foot-head and right-left (RL) rigid motion by tracking a template around the aortic arch, providing motion estimates in a beat-to-beat basis. Foot-head motion is used to sort the 3D CMRA data in 5 equally populated bins, and 3D CMRA images reconstructed at each respiratory position are used to estimate non-rigid motion between bins (B). 2D translational beat-to-beat and 3D non-rigid bin-to-bin motion is then integrated into an in-line motion-compensated iterative SENSE reconstruction to produce the final images