Feasibility Study for Dual Phase Free Breathing 3D bSSFP MRA With Preserved Eddy-Current Tolerance With Adaptive...

To demonstrate the feasibility of a novel dual-phase self-navigated, free-breathing balanced steady-state free-precession whole-heart MRA acquisition for aortic annulus size measurement using a Cartesian trajectory that mitigates eddy-current artifacts by minimizing k-space jumps between consecutive readouts with predictable scan times.

The proposed method uses a trajectory with Preserved Eddy-current Tolerance with Adaptive k-space Lengths (PETAL) that enables the acquisition of multiple navigators per heartbeat to address respiratory motion throughout a 330-510 ms acquisition window across different cardiac phases. Imaging was performed in 15 healthy volunteers on a 3 T MR system using a sequence compiled in Pulseq. Images were reconstructed in systole and diastole. Aortic annulus perimeter and area were measured for both cardiac phases. A clinical MRA and a breath-held 2D bSSFP cine planned at the valve plane were used to statistically compare metrics in diastole and systole, respectively.

In diastole, the PETAL sequence yielded a high correlation with the clinical reference for aortic annulus area ( $\mathrm{ICC}=0.987$ ) and perimeter ( $\mathrm{ICC}=0.996$ ) and low bias (0.008 cm² and -0.018 cm, respectively), with no statistically significant difference. In systole, the proposed method presented a high correlation with the reference for aortic annulus area ( $\mathrm{ICC}=0.989$ ) and perimeter ( $\mathrm{ICC}=0.986$ ), bias of 0.02 cm² and 0.073 cm, respectively, no statistically significant difference for aortic annulus area and a statistically significant difference for perimeter ( $p=0.029$ ).

The proposed approach enables dual-phase, contrast-free, free-breathing acquisition of isotropic 3D whole-heart images in predictable 10 min scan times for aortic size measurements in systole and diastole.