Improved respiratory self‐navigation for 3D radial acquisitions through the use of a pencil‐beam 2D‐T 2 ‐prep for free‐breathing, whole‐heart coronary MRA

Purpose In respiratory self-navigation (SN), signal from static structures, such as the chest wall, may complicate motion detection or introduce post-correction artefacts. Suppressing signal from superfluous tissues may therefore improve image quality. We thus test the hypothesis that SN whole-heart coronary magnetic resonance angiography (MRA) will benefit from an outer-volume suppressing 2D-T2-Prep and present both phantom and in vivo results. Methods A 2D-T2-Prep and a conventional T2-Prep were used prior to a free-breathing 3D-radial SN sequence. Both techniques were compared by imaging a home-built moving cardiac phantom and by performing coronary MRA in nine healthy volunteers. Reconstructions were performed using both a reference-based and a reference-independent approach to motion tracking, along with several coil combinations. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared, along with vessel sharpness (VS). Results In phantoms, using the 2D-T2-Prep increased SNR by 16% to 53% and mean VS by 8%; improved motion tracking precision was also achieved. In volunteers, SNR increased by an average of 29% to 33% in the blood pool and by 15% to 25% in the myocardium, depending on the choice of reconstruction coils and algorithm, and VS increased by 34%. Conclusion A 2D-T2-Prep significantly improves image quality in both phantoms and volunteers when performing SN coronary MRA. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.