Motion corrected water/fat whole-heart coronary MR angiography with 100% respiratory efficiency

To develop a framework for respiratory motion-corrected 3D whole-heart water/fat coronary MR angiography (CMRA) at 3T with reduced and predictable scan time.

A 3D dual-echo acquisition and respiratory motion-corrected reconstruction framework for water/fat CMRA imaging was developed. The acquisition sequence integrates a 2D dual-echo image navigator (iNAV), enabling 100% respiratory scan efficiency. Respiratory motion estimated from both the 2D iNAVs and the 3D data itself is used to produce nonrigid motion-corrected water/fat CMRA images. A first study to investigate which iNAV (water, fat, in-phase or out-of-phase) provides the best translational motion estimation was performed in 10 healthy subjects. Subsequently, nonrigid motion-corrected water/fat images were compared to a diaphragmatic navigator gated and tracked water/fat CMRA acquisition. Image quality metrics included visible vessel length and vessel sharpness for both the left anterior descending and right coronary arteries.

Average vessel sharpness achieved with water, fat, in-phase and out-of-phase iNAVs was 33.8%, 29.6%, 32.2%, and 38.5%, respectively. Out-of-phase iNAVs were therefore used for estimating translational respiratory motion for the remainder of the study. No statistically significant differences in vessel length and sharpness (P > 0.01) were observed between the proposed nonrigid motion correction approach and the reference images, although data acquisition was significantly shorter (P < 2.6×10^-4 ). Motion correction improved vessel sharpness by 60.4% and vessel length by 47.7%, on average, in water CMRA images in comparison with no motion correction.

The feasibility of a novel motion-corrected water/fat CMRA approach has been demonstrated at 3T, producing images comparable to a reference gated acquisition, but in a shorter and predictable scan time.