Dear Jimmy,
It has been a long time since I have tried to work with spm matrices,
and then it was only in a specific context, but I'll try to help.
The D matrices should use mm values, not number of voxels.
Therefore the diagonal elements of D should correspond to the
size of the voxels in mm in the respective image (e.g. 4mm x 4mm x 6mm
in epi or 2mm x 2mm x 2mm in standard).
You might also need to put the origin values in the fourth column of D,
again in mm.
Best of luck,
Mark
On Wednesday, October 30, 2002, at 04:18 AM, Jimmy Jensen wrote:
> Dear FSL,
> I want to use the .mat files from SPM as they relate voxel coordinate in
> the image to location in the scanner system. I have tried to use the
> algorithm posted by Mark Jenkinson (Nov 14, 2001): Afsl = Ddest*VS*inv
> (SCdest)*inv(Ddest)*Aspm*inv(VS)*inv(Dsource).
>
> I have then used: flirt -ref func -in func -applyxfm -init Afsl -out
> func2.
> The result is very bad.
>
> I think, that at least one of my possible errors is that I am failing to
> set the Dsource matrix correctly but as a beginner in the imaging business
> I am not sure where I am doing wrong. The Image dimension is 64x64x28. I
> am
> grateful for any suggestions what I am doing wrong and what the Dsource
> matrix should look like.
>
> Best regards
> Jimmy
>
> -------
> Jimmy Jensen, PhD
> Research Fellow
> PET centre
> Centre for Addiction and Mental Health
> 250 College St.
> Toronto, ON, M5T 1R8
> Canada
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