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Abstract #2568

Rapid Volume Shimming with Gradient Reversed EPI

Kevin Koch1, Eric Printz1, Dan Xu1

1GE Healthcare, Milwaukee, WI, United States

It has previously been demonstrated that EPI acquisitions with reversed phase-encode blip polarities can be used to correct image distortions. A by-product of these methods is a shift map that maps the two source images together. Here, we demonstrate that one of the algorithms previously utilized for distortion correction purposes can be modified to produce high-SNR volumetric field maps for shimming purposes. These results suggest that such methods could be used to collect spatially accurate volumetric field maps for shimming purposes in a matter of seconds.

Keywords

accurate acquisition acquisitions added adjusted agreement allows another applications array aspect audience automatically background bandwidth behaved best blip blurring brain briefly calculation channel clear clinical close coefficients coil columnar composite computation consists construct context coordinates cost coverage depicts determined determining developers differentials distorted distribution dual echoes encoded encoding estimation evolution exact expected extended facilitate field form forward frequency full function future gradient gradients homogeneity important increasing indicated individually intensity investigate iteration iterative kernel knowledge limited linear linearized many maps massively mechanism minimal minimization minimizing minutes newton noise noisier noticeably offset optimization paramount particular pixels planar plots polarities polarity post previously prior problem produces projection property protocols rapid receive reduction regularization require required researchers reversed schedule separation shim shimmed shimming shims shot slices smoothing solution solver source spatial spatially specialized squares stabilize starting static step steps successive system target term terms threshold traces trends trimming true typically utilized volume volumetric whereby width