Figure 8.

EPI images corresponding to the B₀ maps shown in Figure 4. Perturbation loops were used to introduce B₀ inhomogeneities and the iPRES(2)-A coil was used for both imaging and B₀ shimming. EPI images with no perturbation (a,e); with the single loop or figure-eight perturbation before shimming (b,f), showing severe geometric distortions (red arrows); after shimming with the optimal switch state and DC current applied to the iPRES(2)-A coil (c,g), showing a drastic reduction in distortions (green arrows); and after shimming with the iPRES(1)-equivalent switch state (d,h), showing only partial or minimal reduction in distortions (orange and red arrows).