Expected Homogeneity Gain and Hardware Requirements for Slice-Wise 3rd Order Dynamic Shim Updating for fMRI

EPI allows for very fast acquisition, and is the “work horse” of conventional fMRI. To exploit the full advantage of applying ultra-high fields to fMRI, sophisticated B0 shim strategies are required. An auspicious approach for improving B0 homogeneity is DSU. As eddy-currents arise from fast switching of shim currents a careful pre-emphasis calibration is necessary. The application of pre-emphasis requires the limitation of the shim fields, which limits the homogeneity gain expected from DSU. This work compares the expected homogeneity gain from a global and a slice-wise DSU shim approach and investigates the hardware requirements for optimal slice-wise dynamic shimming