An RF coil design to enable quintuple nuclear whole-brain MRI

Abstract

Purpose: To bring metabolic imaging based on multi-NMR toward practical use from the RF hardware perspective. Methods: A highly integrated RF coil is designed for whole-brain MRI and MRS targeted to five nuclear species: 1H, 19F, 31P, 23Na, and 13C. Dipole antennas and closely loaded local receiver loops are combined in this setup. Results: High-quality in vivo scan results of 1H, 31P, 23Na, and 13C on healthy volunteers have been achieved. For 1H, the transmit efficiency is 77% of a single-tuned commercial head coil (NOVA 8-transmit [Tx]/32-receive [Rx]; NOVA Medical, Wilmington, MA, USA). For 31P, 110% SNR of a dual-tuned close-fit head-birdcage was achieved at the center of the subject, based on MR experiments on a phantom. For 31P, 23Na, and 13C, bench measurements indicate SNR loss of 15%, 27%, and 30% compared with single-tuned conditions. 19F performance has been proven to be similar to that of 1H through bench tests and electromagnetic simulations. Conclusion: With this device, 1H-based anatomic images that are expected to meet clinical requirements, as well as high-quality multi-NMR images and spectra, can be acquired within one scan session without hardware replacement or patient repositioning, enabling morphologic and metabolic MRI within acceptable scan time.