The dopamine system plays important roles in various neurological and psychiatric disorders such as Parkinson's disease, schizophrenia, mood disorders, and attention-deficit hyperactivity disorder. Several positron emission tomography (PET) and single photon emission computed topography (SPECT) tracers have been developed including \[11C\]CFT and \[123I\]beta-CIT. These tracers have been successfully applied in patients, particularly to stage those with Parkinson's disease. However, these tracers lack selectivity among monoamine (dopamine, serotonin, and norepinephrine) transporters. Recently a new PET tracer, \[18F\]FECNT brain uptake and washout has been developed, which has high selectivity and affinity to the dopamine transporter (DAT). Part 1 of this study will measure the kinetics of \[18F\]FECNT brain uptake and washout. Part 2 will estimate radiation-absorbed doses in healthy human subjects by performing whole body PET imaging studies. Part 3 will assess the reliability of measuring DAT densities in the brain by performing a test retest brain PET studies in healthy human subjects. The results of this overall study are required to apply this tracer in various neurological and psychiatric disorders in the future.
INCLUSION CRITERIA: Healthy subjects ages 18-65 EXCLUSION CRITERIA-WHOLE BODY IMAGING: Current diagnosis of psychiatric disease, substance dependence or severe systemic disease. History of substance abuse within 6 months. Abnormal laboratory tests. Prior participation in other research protocols within the past year such that a radiation exposure together with the present study would exceed the annual limits. Pregnancy and breast feeding. HIV positive. EXCLUSION CRITERIA-DYNAMIC BRAIN IMAGING: Current diagnosis of psychiatric disease, substance dependence or severe systemic disease. History of substance abuse within 6 months. Abnormal laboratory tests. Novocain allergy. Prior participation in other research protocols within the past year such that a radiation exposure together with the present study would exceed the annual limits. Any condition that increases increase risk for MRI (e.g., pacemaker, metallic foreign body in the eye). Pregnancy and breast feeding. HIV positive.