Yes. As Bruce mentioned you can also use the program that creates the wmparc (mri_aparc2aseg). You can look in the recon-all.log file for the command line (there will be two in there, one to create aparc+aseg and one to create wmparc). You can run this command with --wmparc-dmax to set the maximum distance from cortex to dilate the voxels. Make sure to name the output something other than wmparc.mgz so you don't overwrite what is there. When it is done, there will be a WM label for each cortical label. Is this what you want? It won't do this for subcortical structures.
doug

On 11/04/2013 12:25 PM, Corinna Bauer wrote:

ok thanks, I'll give that a try. I would have to do that for each of the segmentations of interest and I get the number from the LUT?

On Mon, Nov 4, 2013 at 11:47 AM, Douglas N Greve <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>> wrote:


    There is not a single command to do it, but you could do something
    like

    mri_binarize --i aparc+aseg.mgz --wm --o wmmask.mgz # mask of
    white matter
    mri_binarize --i seg.mgz --match 17  --o mask17.mgz # mask of seg 17
    mri_binarize --i seg.mgz --match 17 --dilate 2 --o mask17.dil2.mgz #
    mask of seg 17 dilated by 2 voxels
    fscalc wmmask.mgz and mask17.dil2.mgz --o mask17.dil2.wm.mgz  # seg 17
    inside WM
    mri_concat mask17.mgz mask17.dil2.wm.mgz  --sum --o mask17+wm.mgz
    # seg
    17 plus dilation into WM

    doug


    On 11/04/2013 11:38 AM, Corinna Bauer wrote:
    > Hello all,
    > Is there a way to expand a GM label into the white matter by n
    voxels?
    >
    > Corinna
    >
    >
    > _______________________________________________
    > Freesurfer mailing list
    > Freesurfer@nmr.mgh.harvard.edu

    <mailto:Freesurfer@nmr.mgh.harvard.edu>

    > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer

    --
    Douglas N. Greve, Ph.D.
    MGH-NMR Center

    greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>
    Phone Number: 617-724-2358 <tel:617-724-2358>
    Fax: 617-726-7422 <tel:617-726-7422>

    Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting
    <http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting>
    FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2
    www.nmr.mgh.harvard.edu/facility/filedrop/index.html
    <http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html>

    Outgoing:
    ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/

    _______________________________________________
    Freesurfer mailing list

    Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu>

    https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer


    The information in this e-mail is intended only for the person to
    whom it is
    addressed. If you believe this e-mail was sent to you in error and
    the e-mail
    contains patient information, please contact the Partners
    Compliance HelpLine at
    http://www.partners.org/complianceline . If the e-mail was sent to
    you in error
    but does not contain patient information, please contact the
    sender and properly
    dispose of the e-mail.

--
Douglas N. Greve, Ph.D.
MGH-NMR Center
greve@nmr.mgh.harvard.edu
Phone Number: 617-724-2358
Fax: 617-726-7422

Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting
FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2
www.nmr.mgh.harvard.edu/facility/filedrop/index.html
Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/