B shimming for in vivo magnetic resonance spectroscopy: Experts' consensus recommendations.

Magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) allow the chemical analysis of physiological processes in vivo and provide powerful tools in the life sciences and for clinical diagnostics. Excellent homogeneity of the static B magnetic field over the object of interest is essential for achieving high-quality spectral results and quantitative metabolic measurements. The experimental minimization of B variation is performed in a process called B shimming. In this article, we summarize the concepts of B field shimming using spherical harmonic shimming techniques, specific strategies for B homogenization and crucial factors to consider for implementation and use in both brain and body. In addition, experts' recommendations are provided for minimum requirements for B shim hardware and evaluation criteria for the primary outcome of adequate B shimming for MRS and MRSI, such as the water spectroscopic linewidth.