Local shim coils improve B0 homogeneity achieving high signal to noise in preclinical echo-planar imaging recordings

Motivation: In preclinical imaging, echo-planar imaging (EPI) techniques are prone to B0- inhomogeneities resulting in signal reduction and distortions in the acquired image series. While the established method using spherical harmonics (SH) for B0-homogenization is insufficient for strong inhomogeneities, local shim coils (LSC) represent a promising approach. Goal(s): We tested how effectively a new LSC-design reduces B0-inhomogeneities. Approach: The LSCs were placed under the head of an examined rat and the SNR in EPI recordings was compared with the SH method. Results: LSCs reduce B0-inhomogeneities more effectively than the SH method, resulting in higher overall SNR and less distortions in EPI recordings. Impact: In preclinical fMRI, local shim coils reduce B0-inhomogeneities more effectively than the established method based on spherical harmonics achieving higher signal to noise and less distortions in echo-planar imaging recordings.