Implications of Posture Changes on Local SAR and B1+ Homogeneity in RF Shimming at 3T

Desmond Teck Beng Yeo¹, Zhangwei Wang², Ileana Hancu¹

Predicting local SAR risks in multi-channel transmit MR systems is a challenging task. One approach uses EM simulations to predict local SAR while optimizing the voltage feeds complex weights to obtain a uniform excitation profile. The weights are then applied to the coils voltage sources and the RF waveforms monitored to ensure they conform to the calculated weights. This approach provides some information about local SAR risks. Our work uses EM numerical computations and a posable HBM to investigate how B1+ homogeneity and local SAR may change when optimized weights are applied after a subject is repositioned following RF shimming optimization.