Dear FSL-list,
I have a question regarding the FEAT-unwarp procedure, which i started using to unwarp DWIs.
It works fine, but I noticed that the absolute voxel-wise intensity values of the unwarped images are ~70 times higher compared to the original images. As input to unwarping in FEAT i used a) the betted magnitude image and b) a phase-difference image, which has been scaled to -pi...+pi, unwrapped with Prelude, divided by delta-TE to get rads/second and centered to the median.
According to fslstats -R, my distorted DWI-b0 image ranges from 0.000000 4095.000000, wheras the undistorted image ranges from 0.000000 295356.68750
Is this normal behaviour or has something gone wrong ?
Thank you very much in advance,
andi heckel
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