Dear Mike,
> I had another thought about doing proportional scaling within SPM, but to
> an external variable - SPM defaults to its own measure of mean global
> uptake (in the case of SPECT) for PS. You could enter your external ROI
> counts in the SCALE field of the header for each file. This would
> effectively rescale your data and allow you to run proportional scaling
> within SPM
You could divide the value in the SCALE field by the external ROI count,
and then run the analysis with 'No global normalisation' (because you have
already done the scaling). This would replicate the spm proportional scaling
but with your own mean value.
Cheers,
Matthew
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