[Freesurfer] RAS to MNI coordinates of a label

Hi all,

I am interested in obtaining the MNI or talairach coordinates of a label. The procedure that I have performed is the following:

First of all I have performed a QDEC analysis. From the results, I have drawn a label of a significant area of the brain, that corresponds to the cingulate. Afterwards, I have used the matlab function read_label to obtain the RAS coordinates of this label. To transform these coordinates into mni coordinates, I have read that

if v = [R A S 1]' and X matrix is the matrix from talairach.xfm, then vMNI = X*v

Taking this into account, I have used the X matrix from the talairach.xfm of "fsaverage" (where the results of qdec are mapped). This matrix is

1.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 1.0 0.0 so vMNI is the same as v. When I introduce v (or vMNI) coordinates into a MNI atlas, I don't obtain the cingulate.

Could you please help me with this procedure?

Thank you in advance, Yolanda