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

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 ³¹P MRS(I) at 9.4T, achieving full-brain coverage and reasonable transmit and receive performance at both frequencies.

First, we developed numerical models of dual-row TxRx arrays for ³¹P (loop array) and ¹H (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.

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.

As a proof of concept, we developed the 32-element DT UHF tight-fit TxRx human head array coil for ³¹P MRS(I) with good ¹H 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.