Modeling and analysis of PET studies with norepinephrine transporter ligands: the search for a reference region

The reboxetine derivatives show a lot of promise as tracers for human PET studies of the norepinephrine system. We have identified a strategy for normalizing DVs to a reference region with the understanding that the DVR for these tracers may not be related to the binding potential in the same way as, for example, for the dopamine tracers, since the non-NET binding may differ between the target and nontarget regions. From our baboon studies the average DVR for thalamus (n=18) for SS-MRB is 1.8; however, the lower limit is most likely less than 1 due to this difference in non-NET binding.