Dear Gabriel,
You cannot use imcalc directly because the absolute uptake of tracer is meaningless and influenced by lots of external factors (biodistribution, blood glucose, injected dose, uptake time etc...etc...etc...).
You should first scale the PET images to a meaningful scale (e.g.: global mean, cerebellar uptake, a reference region etc...). Then you could do the imcalc procedure.
This is for simple qualitative PET FDG images. If you have fully quantitative tracer studies, then of course you can just proceed with imcalc directly.
________________________________________
Da: SPM (Statistical Parametric Mapping) <[log in to unmask]> per conto di gabriel robert <[log in to unmask]>
Inviato: giovedì 29 marzo 2018 09:40:57
A: [log in to unmask]
Oggetto: [SPM] Model change in PET with covariate
Dear SPM experts,
We would like to test for an association between changes in PET activity (pre-post surgery) with change in a given clinical variable. For example, do the change in anxiety before and after surgery is associated with the change in metabolism before and after surgery ?
We could calculate the difference in PET maps using ImCalc and then run a regression using the change in the clinical variable as a variable of interest but we were wondering if we could do that in a more clever way in SPM ?
Many thanks,
Best wishes,
Gabriel
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