Efficacy and Safety of F-18 FPCIT PET in Parkinson's Disease and Essential Tremor Patients

Inclusion Criteria: Parkinson's disease * Male or female with age over 40 years * Clinical diagnosis of Parkinson's disease * Ability to give informed consent Essential tremor * Male or female with age over 40 years * Clinical diagnosis of Essential tremor * Ability to give informed consent Healthy volunteers * Male or female with age over 40 years * No any symptoms or sign suggesting Parkinson's disease or essential tremor * Ability to give informed consent Exclusion Criteria: Parkinson's disease and essential tremor * Current pregnancy and breast feeding * Current or past medical history of cardiac and neuropsychiatric disease * Clinical evidence of dementia * Inability to hold antiparkinsonian medication * History of surgical therapy for tremor * Severe or unstable medical or psychiatric condition * Medication affecting CNS in last 6 months(e.g. CNS stimulants, sympathomimetics) * Prior participation in other research protocol within 30 days Healthy volunteers * Current pregnancy and breast feeding * Current or past medical history of cardiac and neuropsychiatric disease * Severe or unstable medical or psychiatric condition * Drug abuse or medication affecting CNS (e.g. CNS stimulants, sympathomimetics) within 6 months * Prior participation in other research protocol within 30 days