Once you're tracking is set right, if you're still not getting fibers you
can dilute your voxel to a larger ROI and then apply a WM mask to the
resulting image (see Hagmann, HBM, 2006; ImageJ also useful). You may want
to do this anyway, since tensors in grey matter voxels can have wonky
orientations and estimation of fibers in low-FA regions is relatively
It would also be important to check some anatomy textbooks and see what
kinds of tracts you'd expect to connect to your voxel, that can only help
inform your results.
hope this helps,
On Wed, 5 Aug 2009 15:52:49 +0100, Massieh Moayedi
<[log in to unmask]> wrote:
>I've been trying to use PROBTRACKX to track fibres from a single-voxel seed
>in the pregenual ACC. The voxel is gray matter in a region of high crossing
>fibres. Each time I run probtrackx it generates almost no fibres,
>essentially stopping in that voxel. I've tried tracking from the closest
>white matter region but I get the same results.
>My bedpostx folder has all of the dyads and f1 and f2 files, so I believe it
>should be able to track from this voxel despite the crossing fibres.
>Do you have any suggestions?
>Is there a way to specify a region around a voxel as the seed? (i.e. a 5x5x5
>ROI centered at my voxel of interest)