I don't think we have anything that will grow a mask on the surface. A slightly hacky way to do it would be to create a binary mask on the surface in which your seed vertex is 1 and all others 0 (you can do this on the cmd line with mri_volsynth with the following options --pdf delta --delta-crsf vertexno 0 0 0 0). You can then smooth it with mri_surf2surf. You can specify the number of dilations with the number of smoothing steps (--nsmooth-in), then use mri_binarize to threshold at some value just above 0 (eg, 10e-10).
doug
Nathan Dankner wrote:
Hello all. I am considering using peak activation voxels (with coordinates either in talairach or MNI space) gleaned from fmri studies in our lab to determine a priori areas of interest for examining group differences in cortical thickness. Is this something that is possible in freesurfer? In particular, I would ideally like to be able to tell freesurfer how large of an area to examine around a particular peak voxel for each subject as opposed to tracing an ROI each time. I am not particularly well versed in the technical aspects of things such as blurring kernels, but I am assuming that the amount of blurring done by freesurfer will affect the ideal circumference of any sphere around this peak voxel. Any suggestions as to how to go about this? Please let me know if any more information is necessary. Thanks,
Nathan
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