Kinetic analysis of [(18)F] altanserin bolus injection in the canine brain using PET imaging

BACKGROUND: Currently, [(18)F] altanserin is the most frequently used PET-radioligand for serotonin(2A) (5-HT(2A)) receptor imaging in the human brain but has never been validated in dogs. In vivo imaging of this receptor in the canine brain could improve diagnosis and therapy of several behavioural disorders in dogs. Furthermore, since dogs are considered as a valuable animal model for human psychiatric disorders, the ability to image this receptor in dogs could help to increase our understanding of the pathophysiology of these diseases. Therefore, five healthy laboratory beagles underwent a 90-min dynamic PET scan with arterial blood sampling after [(18)F] altanserin bolus injection. Compartmental modelling using metabolite corrected arterial input functions was compared with reference tissue modelling with the cerebellum as reference region. RESULTS: The distribution of [(18)F] altanserin in the canine brain corresponded well to the distribution of 5-HT(2A) receptors in human and rodent studies. The kinetics could be best described by a 2-Tissue compartment (2-TC) model. All reference tissue models were highly correlated with the 2-TC model, indicating compartmental modelling can be replaced by reference tissue models to avoid arterial blood sampling. CONCLUSIONS: This study demonstrates that [(18)F] altanserin PET is a reliable tool to visualize and quantify the 5-HT(2A) receptor in the canine brain.