Abstract: To achieve a uniform magnetic field in an MRI system, fitting can be performed using a partially differentiated residue phase map, differentiated shim functions, radial weights, a regularization factor, a discontinuity mask, and/or a signal intensity mask to determine coefficients for shim functions. The fitting can be performed iteratively, where the regularization factor is stronger and the radial weights focus on areas of higher confidence during earlier iterations. During later iterations, the regularization factor gradually gets weaker and the radial weights gradually focus on areas of lower confidence.

Abstract: To achieve a uniform magnetic field in an MRI system, fitting can be performed using a partially differentiated residue phase map, differentiated shim functions, radial weights, a regularization factor, a discontinuity mask, and/or a signal intensity mask to determine coefficients for shim functions. The fitting can be performed iteratively, where the regularization factor is stronger and the radial weights focus on areas of higher confidence during earlier iterations. During later iterations, the regularization factor gradually gets weaker and the radial weights gradually focus on areas of lower confidence.