A Quadruple-Tuned RF Coil System for ¹H/¹⁹F/²³Na/³¹P Synchronous MR Imaging and Spectroscopy at 3 T

The simultaneous acquisition of biological information at different levels of tumor molecular targets, energy metabolism, ion perturbations, and structural function is significant for tumor research, as magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are crucial tools for comprehensive characterization of tumor pathology and monitoring tumor treatment response. As a critical component of RF signal acquisition, the RF transceivers provide the detection capability of signals. Most of the acquisitions for detecting weak nuclei mainly use double-tuned probes or RF coils and multituned coils with limitations. There is currently no reported quadruple-tuned multichannel RF coil design to support simultaneous imaging of four nuclei for animal studies at 3 T. In this work, we developed an innovative quadruple-tuned multichannel transceiver coil array for synchronous 1H/19F/23Na/31P MR imaging in animals at 3.0 T, which provided a potential tool for tumor research at different levels of tumor molecular targets, energy metabolism, ion perturbations, and structural function in MRI application. In contrast to receive-only RF coils, the proposed RF coil system supports multichannel parallel excitation and parallel reception for all four nuclei (1H, 19F, 23Na, and 31P) and enables ${B}_{{1}}^{+}$ shimming to control the transmit field distribution. In order to maximize the signal-to-noise ratio (SNR) for all nuclei, a detuning control strategy was innovatively utilized to counteract the electromagnetic interference in the RF system. Bench tests and numerical simulations were conducted to assess the performance of the developed quadruple-tuned RF coil system. The phantom and in vivo imaging experiments were performed on a 3-T scanner with multinuclear imaging capability to evaluate the practicability of our developed design, where SNR of the quadruple-tuned coil was compared with 1H/19F double-tuned coil array and 23Na/31P single-tuned coil arrays. The results demonstrated that the proposed quadruple-tuned RF coil system possessed high sensitivity and relatively homogeneous RF transmission and reception profiles with the ability to image 1H, 19F, 23Na, and 31P synchronously, which has the potential to simultaneously provide physical, biochemical, and functional information for tumor research in addition to structural information.