I am interested in the differences between Total Intracranial Volume and brain size. Someone can tell me that?
This paper has some useful information about the total intracranial volume and brain volume. Basically, it seems to add some CSF and meninges to the brain volume limited by the extent of gray matter tissue, but otherwise very similar.
In AFNI, you may want to compare the results of 3dSkullstrip, @SSwarper and 3dIntracranial (this last one hasn’t been maintained in a very long time).