deletions | additions       diff --git a/Freesurfer_uses_an_atlas_scaling__.tex b/Freesurfer_uses_an_atlas_scaling__.tex  index a78e5ae..a2d9b20 100644  --- a/Freesurfer_uses_an_atlas_scaling__.tex  +++ b/Freesurfer_uses_an_atlas_scaling__.tex 
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Freesurfer uses an atlas scaling factor (ASF) to calculate the eTIV, so even though the ROI encompasses all others, it is not calculated in the same way as other ROIs (i.e. by counting the voxels inside the skull). Rather, it estimates a linear transformation to an atlas space (Talairach) and calculates the determinant of the transformation matrix, which correlates to ICV \cite{buckner2004unified}. So actually the mechanism behind the biases in eTIV are different than those behind other regional volumes (i.e. regional varaition in CNR and gradient distortions affect the boundary). \textbf{Should I remove eTIV from the table then?} then, but keep in supplemental?}