Hi all,
I have fMRI data in individual space, converted to individual surface using
vol2surf and to fsaverage surface using surf2surf (commands [1] and [2]
below). With Matlab, I obtain the vertex with the maximum value: max_Vtx
and max_Vtx305. If I would like to obtain the MNI152 coordinate of this
vertex (for comparison with the literature), I think I have two options:
1.- Work in the individual space:
>> max_SurfaceRAS = lhwhite(max_Vtx, :);
>> max_RAS = T1.vox2ras*inv(T1.tkrvox2ras)*[max_SurfaceRAS';1];
I can check in freeview that the result is correct.
>> max_RAS305 = TalXFM * max_RAS;
I can check in tkmedit that this is right too.
At last, using the MNI305to152 matrix provided by Doug in the wiki:
>> max_RAS152 = MNI305to152 * max_RAS305;
2.- Work in the fsaverage (305) space
>> max_SurfaceRAS305 = lhwhite305(max_Vtx305, :);
as Surface RAS is the same as RAS, we only have to convert it to 152
>> max_RAS152_305 = MNI305to152 * max_SurfaceRAS305 ;
The results are:
For 1: [-15.57, -93.62, -2.84]
For 2: [-23.06, -97.06, 1.35]
Is this method ok? is this the way it should work? As the results are not
the same, is one of the methods inherently better than the other?
Many thanks!
Gari
[1] mri_vol2surf --srcsubject S001 --projfrac 0.5 --interp trilinear
--hemi lh --regheader S001 --mov fMRI.img --o fMRI.mgh
[2] mri_surf2surf --srcsubject S001 --srchemi lh --srcsurfreg sphere.reg
--trgsubject fsaverage --trghemi lh --trgsurfreg sphere.reg --sval fMRI.mgh
--tval fMRI305.mgh --sfmt curv --noreshape --no-cortex
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