hi miro,

as per me, i would suggest to divide ICV with TotalGrayVol and other aseg.stats files' global measures to remove the invariability across these measures. divide ICV to totalgrayvol,corticalwhitemattervolume,supratenorialvol,subcorticalgrayvol...this will remove any in-variability within those measures across ICV......

hope that helps

kk

----- Original Message ----- From: "Miro Drahos" miroslav.drahos@ucsf.edu To: freesurfer@nmr.mgh.harvard.edu Sent: Thursday, June 21, 2012 2:21:13 PM Subject: [Freesurfer] correcting for normal inter-cranial variability

Hi all, When analyzing output measures from FreeSurfer, what is the proper way to correct for normal anatomical variability before comparing between subjects? Which variable should be used to calculate normalized measures?

volumetric measures -- total intra-cranial volume? total brain volume? surface measures -- total surface area? thickness measures -- mean thickness?

Thank you! Miro Drahos

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