Jurgen,
To create thickness difference maps, follow the instructions on this page:
http://surfer.nmr.mgh.harvard.edu/fswiki/ThicknessRepeatibility
In your case, you would skip step 1, since the recon-all -long will create the .lta transform (from tp1 to tp2) already (look for it in the tp2subj/mri/transform dir). You can use this .lta file to transform the T1.mgz image in tkmedit, so that they are in the same stereotactic space, for viewing.
If you are not doing a group analysis, then you only need to run step 2, mri_thickness_diff, which creates the overlay file. Note that smoothing is not done (as was the case in the thickness repeatability study from which these steps originate).
You would do mri_surf2surf if doing a group analysis, per the instructions.
Nick
On Mon, 2009-02-16 at 18:42 +0100, J=?ISO-8859-1?B?/A==?=rgen H=? ISO-8859-1?B?5A==?=nggi wrote:
Dear FS experts
I had run recon-all -long on two time points and would like to subtract the cortical thickness maps of the two time points.
Do the two ?h.thickness maps of the different time points are already in the same space so that they can be directly subtracted in MATLAB?
Or
Do I have to use mri_surf2surf to register them before I can subtract them?
Do you recommend smoothing the thickness maps?
When looking at T1.mgz with the overlaying aseg the images of the two time points are not in the same stereotactic space: hence, I would like to known whether this is also the case for the thickness maps.
Sorry for reposting this question
Thanks Regards Jürgen
Juergen Haenggi Ph.D. (Dr. des.) Division Neuropsychology Institute of Psychology University of Zurich Binzmuehlestrasse 14, PO Box 25 8050 Zurich, Switzerland 0041 44 635 73 97 (phone office) 0041 76 445 86 84 (phone mobile) 0041 44 635 74 09 (fax office) BIN 4.D.04 (office room number) j.haenggi[at]psychologie.uzh.ch (email) http://www.psychologie.uzh.ch/neuropsy/ (website) http://www.juergenhaenggi.ch (private website)
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