Cardiac Phosphorous MRS Imaging

All scans were performed on a 3.0 Tesla MR system (Prisma; Siemens Healthineers, Erlangen, Germany). All participants were scanned at approximately the same time of the day between their first and second scans. ³¹P-MRS was performed to obtain the rest PCr-to-ATP ratio from a voxel placed in the midventricular septum, with the subjects lying supine with the ³¹P transmitter/receiver cardiac coil (RAPID Biomedical, Rimpar, Germany) placed over their heart, in the isocenter of the magnet. Coil position was standardized to be placed above the midventricular septum. ³¹P-MRS data were acquired with a nongated three-dimensional acquisition-weighted chemical shift imaging sequence (16 ). The acquisition matrix was 16 × 8 × 8 for the protocol. Field of view was 240 × 240 × 200 mm. The acquisition was run with a fixed repetition time of 720 ms.