Evaluation of Myocardial Sympathetic Denervation in Parkinson's Disease Using [18F]FDOPA

Evaluation of Myocardial Sympathetic Denervation in Parkinson's Disease Using [18F]FDOPA

The purpose of this study is to evaluate the added value of PET-CT with [18F]FDOPA tracer for Assessment of the Myocardial Sympathetic Denervation in patients with or suspected with Parkinson's disease.

The investigators expect to see normal values of uptake ratio of [18F]FDOPA , in patients with no synuclein underline pathology or previously known cardiovascular disease (no history of high blood pressure or take medications that influence the sympathetic system- exclusion criteria). Low values of uptake ratio is presumed to be found in patients diagnosed with Parkinson's disease or other synuclein pathology.

The expected normal ratio of Heart/liver uptake values will be determined from scans of patients refered to [18F]FDOPA scan and were found to have normal [18F]FDOPA scan of the basal ganglia and no cardiovascular diseases.

L-3,4-dihydroxy-6-[18F]fluoro-phenylalanine ([18F]FDOPA) might be a useful tracer for assessing myocardial sympathetic denervation in Parkinson's disease (PD) Patients. Compared to the routinely used I123 MIBG scan, [18F]FDOPA seems to have an advantage for the following reasons:

1. meta-iodobenzylguanidine (MIBG) is a false analog of norepinephrine while [18F]FDOPA is the radiolabelled form of DOPA, a direct precursor of dopamine which is subsequently converted to norepinephrine
2. 123I MIBG, un-like norepinephrine, dose not undergo intracellular metabolism (19) while [18F]FDOPA undergo complex intracellular metabolism (17)
3. Studies have shown that I123 MIBG reuptake is almost exclusive by uptake mechanism 1. Uptake-2 mechanism of 123I-MIBG by the myocardium is not significant. Reuptake of norepinephrine (NE) in the synaptic cleft and is mainly by uptake 1 system but also in small amount by uptake 2 systems. The investigators assumption is that this double mechanism of reuptake will increase the concentration of [18F]FDOPA for better imaging

Inclusion Criteria:

1. Age ≥ 18
2. Signed Informed Consent
3. Patients referred for F-dopa scan of basal ganglia in the evaluation of Parkinson's disease or other extra pyramidal motor disorders.
4. Patients diagnosed with Parkinson's disease.

Exclusion Criteria:

1. Age < 18
2. Previous diagnosed Heart Disease.
3. History of High blood pressure.
4. On medications that influence the sympathetic system.