Quantification of the dopamine D2 receptor in the living human caudate nucleus by PET: comparison of in vivo and in vitro kinetic parameters

It is demonstrated that the set of kinetic parameters (including first-order rate constants for the dissociation of N-methylspiperone (NMSP) from, and second-order rate constants for the association of NMSP to, the dopamine D2 and serotonin S2 receptors of the caudate nucleus) which can be derived from previously reported human caudate PET (positron emission tomographic) data is not uniquely determined, but that multiple sets generate approximately equivalent curve fits. In particular, the set consisting of the in vitro values can generate the PET data. Thus, the in vitro rate constants may apply in vivo