[Freesurfer] Question about volumetric group analysis

Hello,

I have two questions about volumetric analysis: First: Are the volume measures in the files aseg.stats or ?h.aparc.stats (Gray Matter Volume) already normalized by ICV? Or should I divide all the structure volumes which I want to compare between subjects by the ICV of each subject? Second: When comparing gray matter volumes the correct is use the ICV or the total cortical gray matter volume to normalize? And if I have to use the total cortical gray matter volume, how can I obtain it? I know that this information is in the aseg.stats file, but I was wondering if I can use asegstats2table to extract it.

Thank you very much,

Fernanda