Hi Jared,

There is not a mask file. The estimated ICV is computed based on a relationship with the talairach transform, not by counting voxels in a mask. On a T1, you cannot actually see the skull because it has such a short T1. People will draw masks using T2 images where they can distinguish between CSF and skull.

doug

Tanner,Jared J wrote:

Hi,

We want to control for intracranial volume in our analyses but we would like verify the reliability and validity of the ICV volume reported in the aseg.stats file (I know the methods reported on the WIki - http://surfer.nmr.mgh.harvard.edu/fswiki/eTIV but haven't seen much in the way of a mask file we could look at). Is there an actual ICV mask file we can look at and load (and potentially edit)? Or, if not, is there an easy way to create an ICV mask?

Thank you,

Jared Tanner University of Florida _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer