On the impact of eddy-current-induced biases in ΔB0 maps on shimming outcomes

Motivation: Eddy-currents can bias magnetic field (∆B0) maps. Goal(s): To assess the impact of eddy-current-biased ∆B0 maps on B0 shimming and T2* measurements. Approach: Measure the shimmed ∆B0 field after having used a ∆B0 map that is thought to be affected by eddy currents vs. one that is obtained using the gradient-reversal technique for canceling eddy-currents. Measure T2* values after using both shimming conditions. Results: Eddy-currents arising from spatial-encoding gradients have a measurable impact on shim quality and can reduce T2* values in the brain by up to 10 ms. Impact: Scientists and clinicians interested in measuring T2* in areas that are affected by strong magnetic field inhomogeneities may want to consider that eddy-current-induced biases in ∆B0 maps could lead to reduced T2* in those regions.