Designs of dielectric pad to improve B1 homogeneity and reduce SAR for the fetal imaging at 3T

Motivation: Performing MRI on fetus at 3T can be clinically valuable but often encounters difficulties in transmit field inhomogeneity and SAR increase. Goal(s): Determine dominant designing factors for optimal dielectric pad configurations to improve B1 homogeneity and reduce SAR for fetus imaging at 3T. Approach: B1 field distributions of transmit body coil with dielectric pads of various designs in different positions around a pregnant woman model were evaluated using computer simulations. Results: The placement of dielectric pad could significantly improve B1 field homogeneity (up to 84%) in the fetus brain. A generalizable routine can be developed for optimization of B1 shimming using dielectric pads. Impact: Passive RF shimming with HPM is a viable ancillary approach for reduction of transmit field inhomogeneity artifacts for body imaging in high field MRI (≥3T), which affect the quality and safety of fetal MRI at 3T.