11C-PIB PET/CT in Patients With Parkinson's Disease and Parkinsonian Dementia Syndromes

Inclusion Criteria: 1. Patients with Parkinson's disease and parkinsonian dementia syndromes 2. Males and females, ≥40 years old 3. The diagnosis of PD is established using the UK Parkinson's Disease Society Brain Bank Research Center Clinical diagnostic criteria. Criteria for PD-MCI and PD-dementia are consistent with those of the Movement Disorder Society. The DLB Consortium consensus criteria are used for DLB. 4. They rely on a combination of neurologic examination and neuropsychological assessment with a battery of tests. Clinical diagnosis was established by sophisticated neurologists. Exclusion Criteria: 1. Females planning to bear a child recently or with childbearing potential 2. Renal function: serum creatinine \>3.0 mg/dL (270 μM/L) 3. Liver function: any hepatic enzyme level more than 5 times upper limit of normal. 4. Known severe allergy or hypersensitivity to IV radiographic contrast. 5. Patients not able to enter the bore of the PET/CT scanner. 6. Inability to lie still for the entire imaging time because of cough, pain, etc. 7. Inability to complete the needed examinations due to severe claustrophobia, radiation phobia, etc. 8. Concurrent severe and/or uncontrolled and/or unstable other medical disease that, in the opinion of the Investigator, may significantly interfere with study compliance. \-