Stefan Skare1,2, Roland Bammer1
1Radiology, Stanford University, Stanford, CA, United States; 2MR Center, Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden
By acquiring EPI data both with positive and negative phase encoding blips one obtains two oppositely distorted images. The reversed gradient polarity (RGPM) method can be used to correct these images by searching for a displacement field that explains their difference. However, even if the estimated displacement field is adequate, the two corrected EPI images have a very low resolution in anatomical regions that have been too compressed. In this work, we use a Jacobian weighting scheme to make an informative choice about the combination of the two images that avoids the inclusion of signals from very compressed regions.