It’s always a good idea to divide the volumes by ICV (or add ICV as a regressor). This is very unlikely, but what if your controls happened to have smaller heads than your patients? For peace of mind, I’d correct by ICV.

Cheers,

/Eugenio

--

Juan Eugenio Iglesias

http://www.jeiglesias.com

From: freesurfer-bounces@nmr.mgh.harvard.edu <freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of Carly McIntyre-Wood <mcintc10@mcmaster.ca>
Date: Monday, July 8, 2024 at 12:06 PM
To: freesurfer@nmr.mgh.harvard.edu <freesurfer@nmr.mgh.harvard.edu>
Subject: [Freesurfer] Is ICV needed as a covariate if matched between groups

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Hi there,

I am investigating differences in hipp/amyg volume between a patient and HC sample and am wondering if there is any reason I would still need to include ICV as a covariate if the groups do not differ on ICV (p=.793).

Thanks so much,

Carly