> Hello,
> 
> I have a set of 12 coronal slices of BOLD fMRI (covering the frontal lobes
> and extending posteriorly to the motor cortex). The Anterior Commissure
> (AC) point is centered at Slice #7. I am trying to transform these images
> into Tailarach space using spm (part of MEDx 3.0). 
> 
> I am running into problems with the final position of the AC point
> ("origin") of my spatially normalized images. Even if I define the outbox
> boundaries accordingly with y dimensions extending the equivalent of 12
> slices and centered around AC point, I find that after the images are
> normalized, the AC point is consistently shifted posteriorly 16 mm from
> where I had set it prior to normalization. What were coronal slices
> (acquired 90 degrees to the AC PC line) are now looking diagonal (tilted
> forward). The dimensions defined by the boundary box are correct.
> 
>  
> Has someone encountered such a problem, or should I assume that since the
> initial data does not cover the whole brain, then I should not expect an
> exact transformation? 
> 
> How to explain the tilting forward (a rotation of 15-20 degrees around
> the X axis)? I suspect that this is what is making the final AC point
> seems more posterior.
> Should I try to modify the Number Basis X (or X, or Z) Functions ? Several
> different combinations did not seems to make much difference.
> Or is the problem with Affine Parameters and Transforms?
> 
> Any comments would be greatly appreciated.
> 
> Thank you in advance
> ZN
> 
> Ziad Nahas, MD
> Medical Director, Brain Stimulation Laboratory
> Functional Neuroimaging Division
> Medical University of South Carolina
> 



Ziad Nahas, M.D.
Research Associate
Medical Director, Brain Stimulation Laboratory


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