the total will be brain plus ventricles. eTIV also includes sulcal csf, so it won't be the same On Thu, 6 Dec 2007, Nick Schmansky wrote:
Paul,
The eTIV calc in freesurfer is an estimate of the total intracranial volume based on a scaling factor determined by the alignment with an atlas. The technique is described in the paper referenced here:
http://surfer.nmr.mgh.harvard.edu/fswiki/eTIV
To my knowledge, its relationship to the other aseg stats has not been explored, but maybe Bruce knows.
Nick
On Thu, 2007-12-06 at 11:10 -0800, Paul Greenberg wrote:
Hi All,
I'm interested in the relationship between estimated total intracranial volume (eTIV), and the volume measures generated in aseg.stats and lh/rh.aparc.stats. I have used freesurfer v3.0.3 for this data set.
Here I am using the output of aseg.stats for all volumes except the cerebral cortex while using the output of aparc.stats exclusively for estimates of cortical gray matter volume. As I'm looking at this data for multiple subjects I've used asegstats2table and aparcstats2table to extract the volume data for each subject (using the "--meas volume" flag).
Question: When I add these volumes generated in aseg.stats (excluding cortex), and rh,lh aparc.stats (cerebral cortex only), should the total be very close to the eTIV value found in aseg.stats?
Thanks, Paul
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