COMPARISON OF METHODS FOR ANALYSIS OF CLINICAL [C-11] RACLOPRIDE STUDIES

Five different methods for the estimation of the binding potential, a measure of B-max/K-d, of [C-11]raclopride in human striatum were compa red using data from a dose ranging study of the neuroleptic CP-88,0590 1. Binding potential was estimated indirectly, from distribution volum es in striatum and cerebellum, using both single- and two-tissue compa rtment models with a metabolite-corrected plasma curve as input functi on. The two-tissue compartment model was also used for a direct estima te of the binding potential. In addition, a direct estimate was obtain ed from the reference tissue compartment model using the cerebellum as indirect input function. Finally, an estimate of binding potential wa s calculated from the ratio of striatum over cerebellum counts at late times after injection. The estimates of striatum binding potential fr om all methods, except the direct determination using a two-tissue com partment model with metabolite-corrected plasma input function, correl ated with each other. Use of an average metabolite correction resulted in only a small reduction in accuracy in this series of normal subjec ts. The reference tissue model provided estimates of the binding poten tial with the same sensitivity for detecting changes as those methods that required a metabolite-corrected plasma input function. This indic ates that for routine analysis of clinical [C-11]raclopride studies, n o arterial cannulation is required. The range of normal values was sig nificantly less variable with the reference tissue method than when si mple striatum-to-cerebellum ratios were used.