Simulation of the RF Shimming Performance of 8 Channel Arrays for 7T Head-Imaging with a Large Diameter Transmit Coil

Motivation: Literature does not provide a comprehensive comparison of different Tx coils' voxel-wise power and SAR efficiency as well as RF-shimming performance for 7T head imaging using a large diameter Tx coil. Goal(s): For nine Tx coils, voxel-wise power and SAR efficiency and RF-shimming performance were investigated to find a optimal Tx coil type for 7T head imaging. Approach: For each coil, the power and SAR efficiency were calculated and compared voxel-by-voxel. L-curves were calculated to evaluate the RF-shimming performance. Results: It was shown that loop-based coils were superior in power and SAR efficiency. The RF-shimming performance was slightly better for dipole-based Tx arrays. Impact: This work demonstrates the potential of different large diameter Tx coil arrays and should help other researchers who want to build a large diameter Tx coil to decide on a suitable coil type.