Dual‐Tuned 31 P‐ 1 H Dual‐Row Loop/Dipole 32‐Element Transceiver Array for Human Brain Spectroscopy at 9.4T

ABSTRACT Purpose The goal of this work is to develop and evaluate a single‐layer tight‐fit 32‐element dual‐tuned (DT) loop/dipole transceiver (TxRx) array for human brain 31 P MRS(I) at 9.4T, achieving full‐brain coverage and reasonable transmit and receive performance at both frequencies. Methods First, we developed numerical models of dual‐row TxRx arrays for 31 P (loop array) and 1 H (coaxial‐end folded‐end dipole array) frequencies at 9.4T. Next, multi‐tissue voxel models were used to simulate Tx‐performance of the arrays and define the optimal CP‐mode excitation. Following this, the proposed array's performance was evaluated by MR measurements both on a phantom and a healthy volunteer. Finally, we compared the proposed array to the previously reported DT single‐row loop‐based TxRx array. Results The developed 32‐element DT TxRx array demonstrated full‐brain (including the cerebellum and brain stem) imaging capabilities, reasonable SNR, and transmit performance at both frequencies at 9.4T. Conclusion As a proof of concept, we developed the 32‐element DT UHF tight‐fit TxRx human head array coil for 31 P MRS(I) with good 1 H performance using a combination of loops and dipoles. The proposed array design could also be adapted to higher fields, that is, 10.5T, 11.7T, and 14T.