Matyas

during the segmentation, you should set the option to save forward and backward deformation (in SPM12 it's at the bottom of the segment batch) -- then simply apply (normalize option) the backward deformation field to your SPM T.

Cyril

From: SPM (Statistical Parametric Mapping) <[log in to unmask]> on behalf of Matyáš Kuhn <[log in to unmask]>
Sent: 25 May 2016 15:51:36
To: [log in to unmask]
Subject: [SPM] MNI to native space - again

Dear SPM users,

I am trying to use dartel deformation field to find peaks from fMRI analysis in native images. There are quite a lot of scripts on mailing list (e.g. https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind1202&L=spm&D=0&P=734555 ) doing so.

I am using SPM 12 and I was thinking that I need to use backward deformation filed (MNI -> native) which I get from deformation utils, but I get only reasonable results using forward deformation field. Am I missing something, like to add some transformation of coords like in the the mail mentioned above - where there is applied affine transformation from Template_6_2mni.mat to coords and then the coords are selected according the backward deformation, but I don't know where to get this mat file. The script I am using is:

deform = spm_vol([[y_forward ',1,1'];[y_forward ',1,2'];[y_forward ',1,3']]);

vox = deform(1).mat\[mni_coords';1];

vx_coords = [...

       spm_sample_vol(deform(1),vox(1),vox(2),vox(3),1)...

       spm_sample_vol(deform(2),vox(1),vox(2),vox(3),1)...

       spm_sample_vol(deform(3),vox(1),vox(2),vox(3),1)];

How to apply the backward deformation instead of forward with SPM12?

Thanks for any advice,

Matyas