do you mean the ones that are between the two surfaces? You could use mris_fill to fill the interior of the white then use it as a mask in mri_mask

cheers Bruce

On Sun, 28 Aug 2016, Fire Tech wrote:

Dear all   I am searching for a solution to remove wm.mgz voxels which are enclosed by pial & white surface. Is there an automated way to do so?   Greetings