AIM: The study presented here firstly compares the distribution of the binding 
potential of the serotonin-5HT2A receptor as measured in vivo with data of 
receptor density taken from literature. Secondly, the sensitivity of the method 
to detect gradual differences in receptor densities is evaluated.
METHODS: Positron emission tomography (PET) studies were carried out in 6 
healthy volunteers using the selective serotonin-5HT2A ligand 18F-altanserin. 
The binding potential was quantified in 12 regions using Logan's graphical 
method and the equilibrium method. These data were compared to the distribution 
of receptor density as taken from literature.
RESULTS: The binding data in vivo correlated to autoradiography data (post 
mortem) with r = 0.83 (Pearson regression coefficient; p < 0.0001). A difference 
in the receptor density between two regions could be detected with p < 0.05 when 
it amounted at least to 18%.
CONCLUSION: This study demonstrates a good agreement between in vivo data 
obtained with 18F-altanserin and PET in healthy volunteers and the true 
autoradiographically determined distribution of 5HT2A receptors in human brains. 
The in vivo method seems to be sensitive enough to detect changes in receptor 
density of more than 18%.