Helmholtz transceiver array for improving the |B1|-field homogeneity at 7-T magnetic resonance imaging

Abstract

A 16-channel transceiver radiofrequency (RF) array using Helmholtz coils was designed to improve the RF transmission |B₁⁺|-field homogeneity for human brain magnetic resonance imaging (MRI) at 7 T. A numerical simulation of the proposed Helmholtz transceiver array was performed using the finite-difference time-domain method—the subset of the finite-element method simulation. The simulation results of proposed 16-channel Helmholtz transceiver array were compared with the generally used rectangular transceiver array in term of their |B₁⁺|-field and specific absorption rate (SAR). The simulation of each single element in 16-channel Helmholtz and rectangular transceiver arrays was compared using water phantom in term of their magnetic flux |B₁| homogeneity for the full width at half maximum. From the simulation results, the proposed 16-channel Helmholtz transceiver array configuration offers superior |B₁⁺|-field homogeneity and low SAR at 7 T. These modifications to the coil geometries of the transceiver array coil could be applied to a 7-T MRI, and also extended to increase the homogenous coverage on |B₁⁺|field with low SAR.