Dear Andreas,
You may want to use "preserve concentration" when normalizing eg. fMRI
images.
Here, if you dilate eg. 1 voxel to 2 voxel, you want to have these
voxels showing the same signal time course, as the original voxel.
Bests,
Auer, Tibor M.D. Ph.D.
Biomedizinische NMR Forschungs GmbH
am Max-Planck Institut für Biophysikalische Chemie
Am Fassberg 11
37077 Göttingen
Germany
Phone/Work: +49-(0)551-201-1725
Phone/Home: +49-(0)551-387-0076
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2010.10.20. 11:02 keltezéssel, Andreas Hahn írta:
> Dear SPM experts,
>
> I have a question concerning the spatial normalization in SPM (5 and
> 8), specifically the writing option to preserve the concentration or
> the total amount.
> From the SPM-help I understand that "preserve amount" means a
> modulation of the image, ie. if the brain is shrinked the signal
> increases there. However, I was wondering why or in which
> circumstances I would choose the option NOT to modulate ("preserve
> concentration"), especially because this is the default option. I
> guess that most VBM studies use modulation, but what about fMRI and
> PET images?
>
> Thank you in advance for your help,
> Andreas.
>
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