Magnetic resonance imaging matrix shim coil system and method

A method for improving image quality in a magnetic resonance imaging system 10 that includes rapidly modulating (132, Fig. 4) an electrical current in a matrix shim coil 86 of the magnetic resonance imaging system, where the rapid modulation compensates high order eddy currents in the system. Also claimed is a method of compensating for B0 field deviations resulting from the alignment of one or more gradient coils 104, 106, by rapidly modulating an electrical current in a matrix shim coil 86. The B0 field inhomogeneities may have high spatial harmonic orders. The rapid modulation may be controlled by a shim driver 110 that provides for dynamic shimming and may be in accordance with a shim waveform. Current in a first shim coil may be modulated independently from a second shim coil. B0 field inhomogeneities maps may be created by mapping one or more reflective fields, and the maps may be used to derive a shim waveform.