Hi Esther, Try fslmaths using the -mas or -Tmin (for more than 2 volumes) options. Best, Eugene On 17 April 2012 09:31, Dr. Esther Pelzer <[log in to unmask]> wrote: > Dear colleagues, > > in order to check the quality of masks between observers during > segmentation, I want to know the intersection voxels between two observers. > When I use fslmerge I just get the total volume of two masks. > > Has someone an idea how to determine the intersection voxels of two masks? > > Cheers, > > Dr. Esther Pelzer > > > >