Dear John,
thanks for your answer. I'd like to follow it up because it wasn't
totally clear for me whether I can or cannot solve the problem.
For example, if you want to do a group analysis with the fMRI data from
two subjects (just an example). Say the data from subject A was aquired
with N slices, the data from subject B with M slices, and N and M are
different.
When you spatially normalize the data, can you use the same bounding box
and voxel size for both subjects? How do you do this?
Thanks,
Jorge
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Jorge Jovicich, Dr. rer. nat
Brain and Cognitive Sciences
Massachusetts Institute of Technology Phone: (617)-452-3127
77 Massachusetts Av., NE20-464 Fax: (617)-258-8654
Cambridge, MA 02139, USA E-mail: [log in to unmask]
http://web.mit.edu/bcs/nklab/
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On Mon, 2 Apr 2001, John Ashburner wrote:
> | the parameter estimation is crushing when we consider fMRI
> | runs that were acquired with different number of slices.
> |
> | Any suggestions for solving this problem?
>
> I'm afraid that this is just one of SPM's limitations. All the images have
> to have the same dimensions, and there has to be no indication that any of
> them have different voxel sizes, orientations etc. This is because a
> voxel in one image needs to correspond with the same voxel in all the other
> images in the series.
>
> If you are using spatially normalised data, then make sure you use the same
> bounding box and voxel size for all subjects.
>
> If it is a single subject analysis, then you can realign and reslice the
> images so they all have the same dimansions (as the first one in the series).
>
> Best regards,
> -John
>
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