Improving Fat Saturation in Upper Extremity MRI with a Local Shim Coil Insert

Motivation: Poor Fat-Sat due to B0 inhomogeneity, especially in off-isocenter regions like the elbow and hand, often obscures critical abnormalities, compromising diagnostic accuracy. Goal(s): Improving B0 field homogeneity and enhancing CHESS Fat-Sat robustness in musculoskeletal MRI, specifically in off-isocenter regions. Approach: A 7-channel local shim insert was developed. Both phantom and in vivo testing were conducted on a clinical 3T MRI scanner, compared with the standard 2nd-order SH shimming. Results: The local shim coil achieved approximately 37.5% reduction in B0 field RMSE, resulting in improved Fat-Sat and increased mean image quality scores for both elbow and hand compared to conventional shimming. Impact: A simple and practical hardware solution to enhance Fat-Sat in musculoskeletal MRI for off-isocenter regions has been developed and tested, expanding MRI accessibility for a broader range of patients.