RF Shimming with Regularization of Maximum & Mean RF Power

Ulrich Katscher¹, Kay Nehrke¹, Peter Vernickel¹, Ingmar Graesslin¹, Peter Brnert¹

RF shimming is able to compensate wave propagation effects at high main fields. The targeted B1 homogeneity has to be counterbalanced by the corresponding mean forward RF power required, which can be described by "regularized" RF shimming. However, this procedure frequently results in heterogeneous power distributions over the different transmit channels, which is disadvantageous for multi-channel RF amplifier design. To achieve comparable power requirements for all transmit channels, this study investigates "double-regularized" RF shimming, minimizing the mean as well as the maximum RF power. The approach was tested successfully in vivo for a whole-body, 8-channel TX/RX system at