COMPARISON OF THE TRANSIENT EQUILIBRIUM AND CONTINUOUS-INFUSION METHOD FOR QUANTITATIVE PET ANALYSIS OF [C-11] RACLOPRIDE BINDING

Several approaches have been applied for quantification of D-2 dopamin e receptors in positron emission tomography studies using [C-11]raclop ride. Initial approaches were based on analyses of data obtained after rapid bolus injection of [C-11]raclopride. A continuous infusion para digm has more recently been applied. The current study compares these approaches in healthy men. Two positron emission tomography measuremen ts were performed in each of six healthy men, the first with rapid bol us injection and the second with continuous infusion of [C-11]raclopri de. In rapid bolus injection, the binding potential was calculated by the following methods. One approach is the kinetic analysis using the standard three-compartment model. Another is to define a transient equ ilibrium at the moment when the specific binding reaches its maximum. In continuous infusion, binding potential was calculated by using time -activity data at equilibrium condition. All methods gave almost ident ical binding potential, representing cross-validation of these methods . The continuous infusion method can provide ''true'' equilibrium cond ition, The kinetic analysis is a sophisticated approach but requires d etermination of an arterial input function. The transient equilibrium method thus is suitable for routine clinical research, since it does n ot require determination of an arterial input function.