Christoph Juchem1, Terence W. Nixon1, Scott McIntyre1, Douglas L. Rothman1, Robin A. de Graaf1
1Diagnostic Radiology, MRRC, Yale University School of Medicine, New Haven, CT, USA
Large differences in magnetic susceptibility result in strong and highly localized field distortions in the human prefrontal cortex, which cannot be addressed by low-order spherical harmonic shimming. A fixed configuration of external, electrical coils has been developed to provide a localized and high amplitude shim field in the prefrontal cortex with minimum impact on the rest of the brain. The experimental realization enabled us to strongly minimize signal dropout for gradient-echo images and settings typically used in fMRI.