The Role of Higher Order B0 Shimming and Intrinsic Gray-White Matter Susceptibility on Spectral Resolution at 7T in the Human Brain

Jullie Pan¹, Hoby Hetherington¹

Potential improvements in SNR and spectral resolution are often cited as a primary advantage for MRSI in moving to higher field strength. However, the improvement in metabolite linewidth is governed by a number of factors including, macro and microscopic (B0Macro, B0Micro) inhomogeneity and the intrinsic T2. At 7T in superior brain locations after 4th order shimming the intrinsic susceptibility differences between gray and white matter represent a majority of the residual inhomogeneity. Metabolite resonances track the water resonance, leading to spectral broadening in voxels with both gray and white matter contributions.