Development of a Double Tuned ²H/³¹P Whole-Body Birdcage Transmit Coil for ²H and ³¹P MR Applications From Head to...

Deuterium (²H) and phosphorus (³¹P) magnetic resonance spectroscopy (MRS) are complementary methods for evaluating tissue metabolism noninvasively in vivo. Combined ²H and ³¹P 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 B₁ ⁺ field. The purpose of this work is to develop a double tuned ²H/³¹P whole-body birdcage transmit coil for 7 T for ²H and ³¹P MRS imaging (MRSI) with homogeneous excitation over a large field-of-view. The performance of the ²H/³¹P birdcage coil was assessed on B₁ ⁺ fields over a body-sized phantom at ²H and ³¹P frequencies using an 8-channel ²H/³¹P receive array. Using two elements of the ²H/³¹P receive array, natural abundance ²H and ³¹P 3D MRSI data at rest were acquired consecutively in the brain and lower leg muscles. Additionally, ²H and ³¹P 3D MRSI data were acquired from one volunteer 90 min after [6,6'-²H₂]-glucose intake, using 8-channel ²H/³¹P receive array around the abdomen. The B₁ ⁺ variation of the whole-body birdcage coil over the phantom was 12.1% for ²H and 19.2% for ³¹P. High-quality ²H and ³¹P 3D MRSI data were acquired from the brain and the lower leg. Whole liver coverage was achieved in both ²H and ³¹P 3D MRSI data. The developed ²H/³¹P whole-body birdcage transmit coil allows simultaneous 3D mapping of glucose and energy metabolism and membrane turnover throughout the human body.