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

Abstract

Purpose: 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. Methods: 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. Results: 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. Conclusion: 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.