dear all
I have some doubts about the procedure for intensity normalisation of PET images in SPM8
I need to normalise to the cerebellum rather than to SPM default setting 'mean voxel value'
after having extracted cerebellar values with Marsbar, I wonder if I have to input them choosing option 'user' in 'global calculation' and then 'proportional scaling' in 'global normalisation', and also if I have to input them as they are or need to elaborate them in some way, because the value I have obtained from Marsbar for each subject is the mean of values extracted from all the cerebellar areas considered, while in the proportional scaling formula the mean VOXEL value (from the brain) is used
and I also wonder how exactly these values will be 'treated' by SPM: if I'm not wrong, proportional scaling multiplies the patient's scan by 50/mean voxel value; does this mean that SPM will multiply the patient's scan by 50/patient's cerebellar value?
thank you in advance for your help!
Pekka H.
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