Slab Selective, Regularized RF Shimming

Ulrich Katscher¹, Ingmar Graesslin, Kay Nehrke¹, Peter Boernert¹

RF shimming, i.e., the optimization of a transmit RF coil array's amplitudes and phases, can by applied to compensate wave propagation effects at high main fields. Selected anatomies, e.g., the legs are particularly prone to wave propagation effects, resulting in significant signal inhomogeneities. This study applies RF shimming to 4 volunteer's legs using eight independent transmit channels at 3T. To optimize RF shimming results, a slab selective, separate excitation of the two legs was evaluated in the framework of frequency-encoded transmission. Furthermore, RF shimming was regularized to avoid inhomogeneity compensation on the cost of high SAR.