Repeatability of 7T Human Cardiac 3D 31P-MRSI Using Concentric Ring k-Space Trajectories

Cardiac phosphorus magnetic resonance spectroscopy (31P-MRS) provides insight into metabolism of the failing heart. The commonly employed 3D-MRS imaging (MRSI) acquisitions are rather slow, even at 7T. Fast readout trajectories, such as concentric ring trajectories (CRT) have been recently suggested to substitute the slow Cartesian sampling of typical chemical shift imaging (CSI), however, their repeatability is yet unknown. We have tested the intra-session and inter-session repeatability of the suggested rapid acquisition (2.5 min) and the time equivalent (6.5 min) high resolution CRT sequences in three healthy volunteers and compared them to the standard 6.5 min CSI scan. The intra-session repeatability was performed as a scan-rescan with the subject in the scanner and the inter-session repeatability was checked by repeating the whole scan three days later. Our preliminary data suggest comparable intra-session repeatability, but somewhat lower inter-session repeatability for mid septal voxels using 2.5 min CRT in comparison to 6.5 min CSI. Similar trends were observed for higher resolution CRT. This work starts to establish the feasibility of using fast or high-resolution cardiac 31P scanning at 7T using CRT.