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

Overview

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