Hi Cyrus,
On Sun, 7 Sep 2008 12:25:57 -0400, Cyrus Raji <[log in to unmask]> wrote:
>Hi, All
>
>So I've been attempting to run VBM 5 on a structural MRI image and I keep
>getting bad results for this one subject in particular (see picture).
>However, I do not believe that it is a problem with the scan itself because
>when I run the unified segmentation using vbm, I get good results and when
>I've segmented this scan with spm2/vbm2 in the past I've also gotten good
>results. My questions (for Dr. Gaser or any other VBM gurus are):
>
>1. Why am I getting these discordant results between the vbm5 and spm5
>processing streams and how I do I fix the discrepancy?
>
The difference is due to the additional "Set origin" option in VBM5. This option is trying to
roughly set the AC by using a center of mass approach, which helps for most images.
However, if the normalization fails you should set the AC manually and set this option to
"use origin from header".
>2. If I want to do VBM, do I need to use the "estimate and write" options
>from the vbm5 toolbox? Why not just use the standard spm5 processing stream?
>
The estimation procedure of SPM5 and VBM5 is the same except the "Set origin" option.
However, if you use the "estimate and write" option in VBM% you have some additional
writing options and you don't have to rewrite the images again.
Regards,
Christian
____________________________________________________________________________
Christian Gaser, Ph.D.
Assistant Professor of Computational Neuroscience
Department of Psychiatry
Friedrich-Schiller-University of Jena
Jahnstrasse 3, D-07743 Jena, Germany
Tel: ++49-3641-934752 Fax: ++49-3641-934755
e-mail: [log in to unmask]
http://dbm.neuro.uni-jena.de
>Any and all input is much much appreciated!
>
>Thank you,
>
>Cyrus
>
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