Chris,
talairach_avi is a wrapper script around the registration tools created
by Avi Snyder of Washington University, namely the tool imgreg_4dfp,
which is the heart of talairach_avi. The wrapper script handles all the
conversions (4dfp,t4 to mgz, concluding with the output of the
talairach.xfm
Nick,
Just a clarification question. I read the wiki regarding the new eTIV and
it says that the registration to
$FREESURFER_HOME/average/711-2C_as_mni_average_305.4dfp.img is done with
talairach_avi as opposed to imgreg_4dfp. I am guessing imgreg_4dfp is
correct because the template has 4df
Mike,
Another piece of info: the talairach.xfm transform is a registration to
an image _with_ skull, to this image:
$FREESURFER_HOME/average/711-2C_as_mni_average_305.4dfp.img
The utility imgreg_4dfp is used to perform this registration. So the
eTIV should not be as subject to changes due to at
Mike,
I've updated our wiki page with most of this info:
http://surfer.nmr.mgh.harvard.edu/fswiki/eTIV
This update, and most of the stats backing it, was done by Martin Reuter
here at the NMR Center.
The wiki page shows the difference in variability between the old way of
calculating it (talair
Nick,
This is great -- you probably also noticed that the version of the
transform used (without or with skull) can make a big difference in the
computed scale factor.
Was variability assessed by comparing eTIV values computed from multiple
MR sessions from the same subject? Or by comparison to
If you make use of the estimated Total Intracranial Volume (eTIV)
calculation found in the aseg.stats file of your subject data, then you
should be aware that we have recently found a more accurate way to make
this calculation. We have found that using the talairach.xfm transform
instead of the ta
