Decreasing SAR of a multi-dimensional central brightening inhomogeneity correction pulse using nonlinear gradient fields and VERSE

Abstract

To correct for B1 inhomogeneity artifacts, multi-dimensional pulses are widely used. However, such pulses increase SAR significantly. In this study, we compare, and combine two SAR reduction methods, the variable rate selective excitation and excitation using nonlinear gradient fields in order to observe their effect on SAR. 5-spoke pulses are designed for both methods to correct for a central brightening inhomogeneity, which is widely seen at the UHF regime. When two methods are used separately, SAR reductions around 75% were obtained whereas when combined, the methods yielded an SAR reduction of 91%.