B0 shimming is important for gradient echo functional MRI where T2* signal loss and precession occur from both physiological and non-physiological susceptibility effects. We used the high degree shim insert (3rd, 4th and two 5th degree shims) to assess its effect for 2mm isotropic whole brain GE-EPI BOLD (breath-hold induced) signal at 7T. Comparing 1st-2nd with high degree shimming, the Δ|B0| changes are spatially varying. For activation, the largest regions of increase are in the inferior frontal region; the largest regions of decrease are in the middle temporal lobe. Overall, there is a 4.3% increase in total activated pixels.
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