Let's say the red spot is overlay.nii.gz

1) convert aparc+aseg from mgz to nii.gz using:

mri_convert aparc+aseg.mgz aparc+aseg.nii.gz

2) create mask between overlay and the atlas using fslmaths:

fslmaths aparc+aseg.nii.gz -mas overlay.nii.gz overlay_overlap.nii.gz

3) use fslstats (or mris_cacl) to compute volume:

fslstats aparc+aseg.nii.gz -k overlay_overlap.nii.gz -V

this output #voxels and volume

Alternatively, you might consider mri_seg_overlap MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be https://surfer.nmr.mgh.harvard.edu/fswiki/mri_overlap

On Fri, Jun 16, 2023 at 10:37 PM parsatad@student.ubc.ca <parsatad@student.ubc.ca> wrote:

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Hello,

Hope you are doing well. I'm new to freesurfer so I was wondering if you could help me out with something please.

I'm looking for a simple way to find the size (i.e. volume in mm³) of overlap between a particular label (1027 ctx-lh-rostalmiddlefrontal) ) in an aparc+aseg file and a NIfTI volume file that can be overlayed on the aparc+aseg file. Please look at the attached file for a better visualization of what I'm describing.

I'd really appreciate it if you could point me in the right direction.

Thank you,

Parsa

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