B1 Shimming Using Passive Surface Coils in the Abdomen

Laura Sacolick¹, Pekka T. Sipilae¹, Mika W. Vogel¹, Ileana Hancu²

Here we present a simple approach for improving B1 homogeneity in the abdomen at 3 Tesla. 3D B1 maps were acquired from 6 subjects in the lower abdomen from the GE HDx whole body transmit coil. The B1 in the abdomen had very similar distributions in all subjects studied. The average B1 distribution among these subjects was used to design and place two tuned passive loop coils to couple to the transmit field and increase the B1 field in regions of low B1. One loop was tuned to 136.5 MHz and placed on the anterior, and one tuned to 141.0 MHz was placed on the posterior abdomen. Significant improvement was found in the transmit B1 field homogeneity in subjects with the corrective coils.