Eigenmode Analysis of Transmit Coil Array for SAR-Reduced B1 Mapping and RF Shimming

Kay Nehrke¹, Peter Brnert¹

The B₁ transmit field inhomogeneity represents a serious problem in whole-body high field MRI (>3T). B1 shimming based on measured B₁ maps is a promising approach to cope with this problem and represents the primary application for parallel transmission at this point in time. However, B₁ mapping is still an error-prone and time consuming process, potentially resulting in a SAR issue caused by the shimmed RF pulse and the mapping scan itself. In the present work, an eigenmode analysis of the transmit sensitivities is employed to accelerate the B₁ mapping process and reduce the SAR of the shimmed RF pulses.