Fig. 3
Typical 31P spectra from a patient with HF (age 45 yrs.; NYHA Class II). a Transaxial scout CMR delineating the MRS voxels (horizontal lines), and approximate locations for the transmit and receive coils (green and orange ellipses). The receiver coil’s region of sensitivity (blue shading) and an embedded coil marker (blue arrow) are also indicated. b Fully-relaxed spectrum from the yellow cardiac voxel in a, showing the PCr and ATP γ-phosphate peaks used for concentration measurements. c-e The TRiST experiment with MRS saturation (red arrows) at + 2.5 ppm as a control (c), and (d, e) at − 2.5 ppm to saturate the exchanging γ-ATP. The MRS repetition periods are 15.7 s, 9.7 s and 1.6 s in (c-e) respectively (see Additional file 1). The decrease in PCr in (d) vs. (c) is proportional to the CK reaction rate, kf (note change in vertical intensity). The total scan time for these acquisitions was about 45 min