Improving B1-Based SAR Determination Via Iterative Determination of Missing Field Components

Ulrich Katscher¹, Karim Djamshidi¹

The additional degrees of freedom available in parallel transmission hamper straight-forward SAR estimations as applied for single channel transmission. As an alternative to the usually applied model-based SAR estimation, SAR can be estimated from individually measured B1 maps. Overall, the accuracy of this B1-based SAR determination is satisfying, however, could be further increased if the hitherto unknown longitudinal component of B1 can be determined. This study investigates an iterative estimation of this component and its impact on the resulting local SAR determination, based on spherical and realistic patient models for an eight-element RF transmit array at 3 T.