Fig 1 . Non water suppressed spectra for a) a small voxel size (20x20x20 mm) and b) a large voxel size (200x200x200 mm) with default vendor implemented shim calibration matrix that contains only diagonal terms and does not consider real shim fields for the 1st – 3rd order spherical harmonic shim coils. While for a small voxel in the isocenter the implemented shim routine converges, this is not the case for a large volume of interest in case of 3rd order B0 shimming. Phantom used: spherical phantom (per Liter MARCOL-oil: 0.011g MACROLEX blue).

Fig.3 Acquired and ideal model static magnetic field maps for the third order shim coils: the top row shows the name of the B0 shim field term; the middle row shows the acquired field maps and the bottom row shows the model field maps. As we can see the acquired maps do not at all match the ideal model for 3rd order shim terms but among other imperfections contain very strong linear field contributions.