this is for holding javascript data
Anisha Keshavan edited Freesurfer_uses_an_atlas_scaling__.tex
about 8 years ago
Commit id: db63e4412b625a27fc05deb67eee2928ded241f2
deletions | additions
diff --git a/Freesurfer_uses_an_atlas_scaling__.tex b/Freesurfer_uses_an_atlas_scaling__.tex
index 2f19298..d6eb267 100644
--- a/Freesurfer_uses_an_atlas_scaling__.tex
+++ b/Freesurfer_uses_an_atlas_scaling__.tex
...
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). Because of this, we have removed the eTIV results since it doesn't make sense to include this particular metric. However, as stated in the previous response, we used eTIV to QC scans, particularly in sites 4,6 and 11 and removed the 1 scan from each site that
was causing the had a bad
scan-rescan reliability. registration. I've included the test retest reliability of eTIV to verify
that the
QC, registrations were consistent, but I have excluded it from the scaling factor calculations and validations.