Signal Considerations in Slicewise Dynamic B0 Shimming.

Saikat Sengupta¹, E. Brian Welch¹, John C. Gore¹, Malcolm J. Avison¹

Dynamic Shimming improves Bo field homogeneity compared with global volume shimming. The most common approach for estimating slice-wise shim values involves removing the redundancy of functionally degenerate shim terms from an in-plane field regression and assuming a linear through plane inhomogeneity profile. This approach yields excellent inplane inhomogeneity compensation but compromises intravoxel signal recovery. Here, we present a slice-wise shim calculation method based on maximizing the voxel signal. Signal simulations and in vivo T2* measurements are presented which demonstrate improved signal recovery performance compared to both the degeneracy analysis and static global shimming approaches.