Hi,
You can exclude the effect of the weighting volume by altering the
percentage Signal loss threshold. If you put that at 100 percent
it should ignore pretty much all areas of signal loss and thus not
apply the mask.
All the best,
Mark
On 11 Mar 2011, at 18:19, Carien van Reekum wrote:
> hi all,
>
> We have come across an issue with the registration step within FEAT
> (first level analysis). When applying a fieldmap correction within
> FEAT, I have noticed that the registration step automatically adds an
> undistorted fieldmap signal loss as a weighting volume. In our data, I
> have noticed that this step actually tilts the functional data, and
> always in a left-right direction, although for some subjects more than
> others. When I apply FLIRT without the weighting volume, the
> registration (to native highres and to standard space) seems fine. The
> fieldmap signal loss volume looks fine, and so do other fieldmap (and
> unwarped) files in the unwarp directory.
>
> Is there an easy fix to include a fieldmap correction within FEAT but
> not use the weighting file in the registration step, or is it better
> to redo the registration afterwards, using transformations obtained
> with FLIRT?
>
> thanks in advance for any pointers,
>
> Carien
>
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> Centre for Integrative Neuroscience and Neurodynamics
> School of Psychology and Clinical Language Sciences
> University of Reading
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