Figure 4.
Results of the ex-vivo porcine tissue imaging experiment. Magnitude, unwrapped phase and standard deviation maps of the phase over all time points for needle in two orientations. Also shown are profiles across the phase maps. In the perpendicular orientation (0,0 90 degrees), needle shimming reduces the signal void significantly. Also, the phase profile shows a sharp gradient in the region outside the already larger signal void without shimming, which is reduced with shimming. Shimming does not reduce the signal void noticeably when the needle is parallel to B0 at (0,−90,0 degrees), indicating that the shim coil tip design for this insert was not optimal for parallel orientations. Slight flattening is however noticed in the underlying phase profile