Hi Bob,
The reference to siemens comes from the fact that siemens has a default field map
creation sequence.
But this kind of distortion correction can apply to both GE and Siemens scanners,
and fbirn is using this kind of correction on both systems.
Its just that the GE folks have to do more work to create the field map than
Siemens folks.
Tom Liu at UCSD has got a field map sequence for GE.
Doug Greve has created a very nice script using fsl that I am using now that I could
probably send along.
It does work -- admittedly, the changes it produces are modest, but noticeable.
I just am reluctant to use fsl tools because of the sform orthogonal ignoring qform problem.
Therefore I was looking for an all afni approach.
But if there is no interest, its not a big deal.
I think I can work with this fsl based script and clean things up at a later stage.
If you would like to see unwarped images, the voxel shift map, and warped (undistorted)
images, I can send them along.
Lee