[Freesurfer] mri_volsynth question

Hi

I am trying to make a subcortical 5 mm sphere ROI around a talairach coordinate. I am using the below command, but when I visualize it, it doesn’t look at the correct location. I see the same question in forum (https://www.mail-archive.com/freesurfer@nmr.mgh.harvard.edu/msg67295.html), I should probably use -pdf delta but I don’t know how to get the col, row and slice indices of the vertex where it should go.

mri_volsynth --template $SUBJECTS_DIR/fsaverage/mri/brainmask.mgz --c_ras -21.8 -12.2 -10.3 --dim 5 5 5 5 —o new.mgh

I appreciate your help.

Thanks Mona

Zahra (Mona) Nasiriavanaki, M.D. Postdoctoral Research Fellow Department of Psychiatry Massachusetts General Hospital 149 13th Street, 149-2615 Charlestown, MA, USA, 02129