Dopamine and PET

Neuroendocrine (NE) tumors include gastroenteropancreatic endocrine tumors [carcinoid tumors and islet cell tumors of the pancreas], pheochromocytoma and medullary thyroid carcinoma (MTC) with their associated familial forms, and neuroblastoma tumors. These tumors have been described as APUD-omas, based on their capacity for amine precursor uptake and decarboxylation.

As a result of this characteristic, the amino acid dihydroxyphenylalanine (L-DOPA) is taken up into the cell and is decarboxylated to form dopamine that is subsequently stored in the storage granules. Based on this process, we initiated a study for carcinoid patients with Prof. Benjamin Glazer and Prof. David Gross from the Department of Endocrinology on the use of F18-Fluorodopa (FDOPA), i.e., L-DOPA labeled with F-18, using PET imaging. A semi-automated one-pot radiosynthesis of [F-18] F-DOPA was developed in our facility.

This simple and reliable automated procedure has been used routinely in our laboratory for the last two years. [F-18] F-DOPA was produced with a 20% yield, with high chemical and radiochemical purity. Initial results of FDOPA PET imaging in 20 patients have shown improved accuracy compared to FDG PET and other conventional imaging methods (MIBG and Octreoscan).