Thank you very much for your reply.
I think I didn't explain the question well. The real question is whether when doing a voxel-wise analysis (or PET or fMRI, not both in the same analysis) it is mandatory to introduce the ICV as a covariate of no interest in the statistical model (as in VBM studies , which is mandatory).
For example, if you want to compare the voxel-wise differences of ReHo between controls and Alzheimer's patients, is it necessary / mandatory to introduce the ICV as a variable of no interest?
Thank you very much in advance and sorry for the inconvenience.
Best regards,
Marina.
