B1+ and SNR Optimization of High Field RF Coils Through Offsetting of Transmit and Receive Elements

Graham Wiggins¹, Qi Duan¹, Riccardo Lattanzi¹, Daniel K. Sodickson¹

In high field MR the B1+ transmit and B1- receive patterns of a surface coil no longer coincide, but twist in opposite directions. When such a coil is used in a transmit-receive mode this leads to a loss of efficiency. Through full wave electromagnetic simulation and experiment we investigate the benefits of using separate transmit and receive elements and offsetting them so that the B1+ and B1- fields curl towards each other. SNR benefits of up to 40% are obtained, and it is found that there is an optimal angular offset for a given depth in the sample.