Positron emission tomography studies of dopamine-enhancing drugs.

Although PET is technologically complex because the restricted time scale requires that radioisotope production, radiotracer synthesis, and PET imaging be carried out in the same place, the payoff is that compounds labeled with these isotopes can be used to track the distribution and movement of drugs in the brain and also measure drug effects on specific molecular targets in the human brain. Provided that appropriate radiotracers are available, one can determine the amount of a drug that gets into the brain, the minimum effective dose, the duration of action, or the binding site occupancy required to elicit a particular therapeutic or behavioral effect with a relatively small number of PET studies. Because studies are carried out directly in humans, the relationship of these parameters to behavior and to therapeutic efficacy can be evaluated. The possibilities are enormous and are largely driven by advances in PET technology (including radiotracer chemistry and instrumentation) that synergize with advances in neuropharmacology.