Development of a Double Tuned H/P Whole-Body Birdcage Transmit Coil for H and P MR Applications From Head to Toe at 7 T.

Deuterium (H) and phosphorus (P) magnetic resonance spectroscopy (MRS) are complementary methods for evaluating tissue metabolism noninvasively in vivo. Combined H and P MRS would therefore be of interest for various applications, from cancer to diabetes. Loop coils are commonly used in X-nuclei studies in the human body for both transmit and receive. However, loop coils suffer from limited penetration depth and inhomogeneous B field. The purpose of this work is to develop a double tuned H/P whole-body birdcage transmit coil for 7 T for H and P MRS imaging (MRSI) with homogeneous excitation over a large field-of-view. The performance of the H/P birdcage coil was assessed on B fields over a body-sized phantom at H and P frequencies using an 8-channel H/P receive array. Using two elements of the H/P receive array, natural abundance H and P 3D MRSI data at rest were acquired consecutively in the brain and lower leg muscles. Additionally, H and P 3D MRSI data were acquired from one volunteer 90 min after [6,6'-H]-glucose intake, using 8-channel H/P receive array around the abdomen. The B variation of the whole-body birdcage coil over the phantom was 12.1% for H and 19.2% for P. High-quality H and P 3D MRSI data were acquired from the brain and the lower leg. Whole liver coverage was achieved in both H and P 3D MRSI data. The developed H/P whole-body birdcage transmit coil allows simultaneous 3D mapping of glucose and energy metabolism and membrane turnover throughout the human body.