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Mark, Yes, I say fieldmaps because this happened to quite a few different acquisitions. So yeah, the problem is that the PE direction is not consistent between the phase maps. I figured there was nothing that could be done to correct this, but just wanted to make sure. Thanks for the help, Carlos On Fri, 1 Aug 2008 18:06:58 +0100, Mark Jenkinson <[log in to unmask]> wrote: >Maybe what you are saying is that the two different >echoes within what I would call one single fieldmap >are different. Is that right? I have assumed that you >have been talking about two completely separate >fieldmap acquisitions (given that you talk about >fieldmap*s* and not just one fieldmap), and that the >individual echo images that go into each fieldmap were >internally consistent. If you have the case where they are >not internally consistent with respect to PE direction, >then I'm afraid there is nothing you can do as the phase >subtraction will leave you with residual phase that >is artefactual. > >Please let me know what the exact situation is. > >All the best, > Mark