Dear freesurfers,
I am new in the list and will start with a hopefully not too stupid question... besides a planned cortical thickness analysis I would like to compare the volumes for some cortical parcellation areas between three groups. As far as I understood the freesurfer-procedures the brains are also stretched during the linear registration in the talairach transformation process. Is this stretching scale factor already accounted for in the volume values displayed in the aparc.statsvolume-file? Or will I have to account for potential deformations due to stretching of the brain by myself? I think it must have been already accounted for, but so far I found no specific notations in the corresponding publications...
Thank you for your help and greetings from Germany
Cindy ____________________________________________________________________ Psssst! Schon vom neuen WEB.DE MultiMessenger gehört? Der kann`s mit allen: http://www.produkte.web.de/messenger/?did=3123
Hi Cindy,
the values in the various stats files are always in the subject's native space. You may want to include eTIV as a regressor in your modeling, but we don't do normalization by default.
cheers, Bruce
On Tue, 10 Feb 2009, Cindy Eckart wrote:
Dear freesurfers,
I am new in the list and will start with a hopefully not too stupid
question... besides a planned cortical thickness analysis I would like to compare the volumes for some cortical parcellation areas between three groups. As far as I understood the freesurfer-procedures the brains are also stretched during the linear registration in the talairach transformation process. Is this stretching scale factor already accounted for in the volume values displayed in the aparc.statsvolume-file? Or will I have to account for potential deformations due to stretching of the brain by myself? I think it must have been already accounted for, but so far I found no specific notations in the corresponding publications...
Thank you for your help and greetings from Germany
Cindy ____________________________________________________________________ Psssst! Schon vom neuen WEB.DE MultiMessenger gehört? Der kann`s mit allen: http://www.produkte.web.de/messenger/?did=3123
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Cindy, the brains are not stretched in any way. All computations are done in native anatomical space. The talairach reg is only there for reporting purposes (or to create average subjects).
doug
Cindy Eckart wrote:
Dear freesurfers,
I am new in the list and will start with a hopefully not too stupid question... besides a planned cortical thickness analysis I would like to compare the volumes for some cortical parcellation areas between three groups. As far as I understood the freesurfer-procedures the brains are also stretched during the linear registration in the talairach transformation process. Is this stretching scale factor already accounted for in the volume values displayed in the aparc.statsvolume-file? Or will I have to account for potential deformations due to stretching of the brain by myself? I think it must have been already accounted for, but so far I found no specific notations in the corresponding publications...
Thank you for your help and greetings from Germany
Cindy ____________________________________________________________________ Psssst! Schon vom neuen WEB.DE MultiMessenger gehört? Der kann`s mit allen: http://www.produkte.web.de/messenger/?did=3123
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
freesurfer@nmr.mgh.harvard.edu
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Bruce Fischl -
Cindy Eckart -
Douglas N Greve