It depends on the space you used for your SPM analysis. If you used the mni152, then you should run recon-all on that, the use mri_vol2surf with --regheader, probably specifying --projfrac-max 0 1 .1
Then use mri_surf2surf to map it to fsaverage space, then use mri_binarize to binarize it at the threshold you want. Finally use the result of that as the --mask option to mri_glmfit. You will need to build your own monte carlo simulation
https://surfer.nmr.mgh.harvard.edu/fswiki/BuildYourOwnMonteCarlo

doug

On 2/23/16 5:50 AM, Daniel Baena Pérez wrote:

Dear Fresurfer users,

I would like to analyze group differences in cortical thickness in fresurfer by using as a mask a volumetric SPM activity image. Which command should be used for this purpose?

Thanks a lot and best wishes,

Sofia
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