Dear FreeSurfer experts,

After searching on FreeSurfer wiki and mailing list, I know that the ICV reported in aseg.stats is an estimated value based on talairach transformation. So, if the talairach transformation for a subject's head is not good, the ICV for this subject is not accurate, am I right?

If this is the case, it may not be suitable to use ICV to adjust the volumetric data in aseg.stats and ?h.aparc.stats for some special subjects. I am thinking of using "brain volume" for this purpose. Here are the steps to get it:

1. Get the surface-based volume of cerebral white matter (aseg.stats).

2. Add up the volumes of all cortical regions to get the surface-based volume of cerebral cortex (aparc.stats).

3. Add up the above volumes (including both hemispheres) and the volumes of all other regions listed in aseg.stats (except for cerebral white matter and cerebral cortex) to get the brain volume.

Is this a suitable way to obtain more accurate brain volume?

Thanks in advance and any suggestions are greatly appreciated,

Xiangchuan Chen