[18F]Altanserin and small animal PET: Impact of multidrug efflux transporters on ligand brain uptake and subsequent quantification of 5-HT2A receptor densities in the rat brain

MDT inhibition led to an increased cerebral uptake of [18F]altanserin but did not improve the reliability of BPND as a non-invasive estimate of 5-HT2AR. This finding is most probable caused by the heterogeneous distribution of P-gp in the rat brain and its incomplete blockade in the reference region (cerebellum). Differential MDT expressions in experimental animal models or pathological conditions are therefore likely to influence the applicability of imaging protocols and have to be carefully evaluated.