Fig. 9.
Reproduced with permission from Stockmann et al. (2016a). Demonstration of static slice-optimized B0 shimming performed at 3 T with the integrated 32ch ΔB0/Rx array coil described in Stockmann et al. (2016a) and shown in Fig. 6c. Three representative slices are compared for conventional global 2nd order shims and for global 2nd order + slice optimized MC shims. The data shown include ΔB0 field maps, undistorted anatomic images, and 1 mm EPI acquired with both anterior-posterior and posterior-anterior and anterior-posterior phase encoding directions and with echo spacing = 1.11 ms and no in-plane GRAPPA acceleration to exaggerate the distortion. The predicted and acquired ΔB0 field maps agree relatively well. MC shimming reduces the standard deviation of ΔB0 in each slice, σB0Local, by up to 55%. The orange line shows reduced distortion with MC shimming at the anterior aspect of the lateral ventricles. EPI parameters: 1 mm in-plane, 2 mm slice thickness, TE/TR = 65/18,940 ms, 6/8 partial Fourier, readout bandwidth 1190 Hz/pixel.