IMPROVED RECEPTOR ANALYSIS IN PET USING A-PRIORI INFORMATION FROM IN-VITRO BINDING ASSAYS

An accurate determination of non-specific binding is required for the analysis of in vitro and in vivo receptor binding data. For some radio ligands the non-specific binding is of the same magnitude as the speci fic binding. Furthermore, in vitro measurements have shown that the no n-specific binding can be different in different brain regions. If thi s is the case in a PET study for determining B-max and K-d, a correcti on for the non-specific binding has to be applied. The aim of the pres ent communication is to present a means for determining corrected B-ma x and K-d with Scatchard analysis using in vitro binding studies. The influence of non-specific binding on the free and specifically bound r adioligand is expressed with the aid of a correction factor, which can be calculated from measurable quantities. Introduction of the correct ed free and specifically bound radioligand should give binding paramet ers closer to reality than previously obtained results.