# Calculate commong/shared voxels

Hi dear mrtrix community!

I have encountered a problem, and I would like to solve it with mrtrix. I hope it is possible!
What I am trying to accomplish is this. I have:

• one ROI mask made from anatomical image of a tract (ex. arcuate fasciculus)
• one tract (ex. arcuate fasciculus) made from tckgen reconstruction

What I want is how many (number) voxels from tckgen reconstructed tract are also consisted in ROI mask made from anatomical image. So basically, just the common/shared voxels of the two!
Images were previously coregistered.

First check that the images have the same transformation: `mrinfo anat.mif tck.mif`, if not you’ll need to regrid at them to the same voxel space using `mrtransform`'s `-template` option (and presumably `-interpolate nearest`).
Then `mrcalc anat.mif tck.mif -mult - | mrstats -output count -ignorezero -` gives you the overlap.