Motion-Induced Frequency and Shim Variations During Localized 1H MR Spectroscopy with Prospective Motion Correction

Brian Keating¹, Thomas Ernst¹

Motion during brain 1H MR spectroscopy may cause susceptibility-induced changes in B0. We used a PRESS sequence with prospective motion correction (PMC) to quantify the effects of motion on center frequency and shim quality. Subjects performed x- and z-head rotations while the MRS voxel tracked head motion. The center frequency displays a linear dependence on both θx (0.01ppm/deg) and θz (0.002ppm/deg). The FWHM is approximately a quadratic function of the θx, but is largely independent of θz. Our results indicate that PMC requires real-time frequency and shim updates in order to recover high-quality spectra in the presence of subject motion.