Weighted and dynamic B­­0 shimming for interleaved MRI and MRS acquisition at 7T using a multi-coil array

Motivation: Interleaved MRI-MRS acquisition offers the potential to probe metabolite and haemodynamic responses, yet achieving optimal B0 shimming in both regions is challenging. Goal(s): Evaluate the performance of weighted and dynamic B0 shimming using a multi-coil shim array. Approach: A B0 shimming algorithm was developed, incorporating a multi-coil shim array together with spherical harmonics, to optimise homogeneity over a small volume and whole-brain, simultaneously. We demonstrate this using simulations developed from phantom and in vivo data. Results: Weighted shimming with the multi-coil shim array improved homogeneity across several commonly measured brain regions and the whole brain relative to using spherical harmonics alone. Impact: Weighted shimming improves homogeneity outside of small regions thus reducing artefacts for MRS. Dynamic shimming with the multi-coil shim array may allow for greater flexibility than updating spherical harmonics alone. This approach improves data quality using interleaved acquisition approaches.