I would suggest preprocessing the data all in exactly the same way. If you
treat one group differently from the other, then you are likely to see
significant differences. Your second option is therefore not so preferable.
I have put my first attempt at a user guide for DARTEL in
http://www.fil.ion.ucl.ac.uk/~john/misc/dartel_guide.pdf
I hope this will be useful.
All the best,
-john
On Wednesday 16 January 2008 23:30, shruthi chakrapani wrote:
> Hello Dr Ashburner,
>
> I have a very basic question regarding Dartel and deformation utility.
> In one of your emails , you say that the registered modulated GM/WM
> images can be warped to the MNI space via registering the group
> averages to MNI data.
> I am not sure how to execute this. I would really appreciate if you
> let me know how to do this.
>
> Since I am trying Dartel for the first time I just want to confirm
> what I am doing is correct. My data set has 2 groups of subjects,
> control group and patient group.
> I am running the Dartel protocol in 2 ways:
>
> First:
> Dartel: Import the seg_sn.mat files for all the subjects (con + patient)
> Dartel: Creating template using both cont and patient subjects
> Dartel: Warp all the images to the average shape (cont + patient).
> Smooth: 6mm
> Stats : Grp comparison in their own space
> Deformation utility : Use to convert to MNI space
> Stats : Grp comparison
>
> Second:
> Dartel: Import the seg_sn.mat files for all the control subjects and
> importing separately for patient group.
> Dartel: Creating template separately for the cont subjects and patient
> subjects Dartel: Warp the images (cont and patient) to their respective
> average shapes Smooth: 6mm
> Deformation utility : Use to convert to MNI space
> Stats : Grp comparison
>
> I am not sure which one is correct or better. I am now stuck with the
> Deformation utility step . If you can let me know how to put all the
> modulated GM/WM images to the MNI space that would be great.
>
> Thanks so much.
>
> -Shruthi
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