Dear SPM'ers
I have a question regarding co-register.
First some background-
I have three T1-weighted volume datasets,
1) 3d volume scan, 256x256x124 voxel dimensions, 0.781x0.781x1.6mm size.
Full brain coverage, coronally acquired.
2) scan 1, manually reoriented to form isotropic voxels of side
0.781, in a sagittal plane orthogonal to the bicommisural plane. I do
not have the transformation matrix from scan 1 --> scan2
3) Scan 2, parcellated to form a dorsal and an orbital 'subfield' of the
prefrontal cortex. All voxels not deemed to be prefrontal cortex are
given a value of zero.
Now, I am interested in ascertaining prefrontal GM and WM values for
these prefrontal subfields, so have segmented scan 1 using SPM99b, and
wish to get GM/WM values for my prefrontal subfields.
I have successfully coregistered scan 2 to scan 1 using the coregister
function in spm (after rotating scan 2 through 90 degrees to put them
in an approximate frame of reference, ie roughly coronal).
I am sure that the parameters that describe the transformation from scan
2 into scan 1 are hidden within an spm .mat file somewhere. If so, as I
understand it it applying that transformation should put the parcellated
images of scan 3 into the space of scan 1.
Is there a way I can do this? Am I missing something straightforward?
I tried to use the .mat file created in the coregistration of scans 1->2
within the normalize function of SPM, but it fails- I guess that there
is a difference between the formats of the _sn3d.mat and other .mat
files.
Can anyone give me some assistance?
Cheers
Matt
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Matt Howard
Magnetic Resonance and Image Analysis Research Centre
University of Liverpool
Liverpool
L69 3BX
Tel 0151 794 5634
Fax 0151 794 5635
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