fluorodopa

Fluorodopa F-18 is the amino acid analog fluorodopa (FDOPA) labeled with fluorine F 18, a positron-emitting isotope. It is diagnostic PET agent, which has been used for decades in imaging the loss of dopaminergic neurons in Parkinson's disease, and more recently to detect, stage and restage neuroendocrine tumours and to search for recurrence of viable glioma tissue. Fluorodopa F-18 is able to cross the blood-brain barrier and is taken up by brain tumor cells. As uptake is higher in tumor cells, tumors may then be imaged using positron emission tomography (PET). Assessing tumor uptake of FDOPA may be beneficial for diagnosis, localization and in determining further treatment. The clinical usefulness of Fluorodopa F-18 has been evaluated and recognised in France and subsequently in several EU countries. Fluorodopa F-18 was registered in France in 2006. 6-fluoro-(18F)-L-3,4-dihydroxyphenylalanine (FDOPA) is a large, neutral amino acid that is transported into presynaptic neurons, where it is converted by the enzyme aromatic aminoacid decarboxylase [AAAD]) into fluorodopamine-(18F), which subsequently enters cathecholamine-storage vesicles. 6-fluoro(18F)-L-dopa crosses the blood-brain barrier; therefore, when injected into the blood stream, it reaches the dopaminergic cells in the brain and is used by the brain as a precursor for dopamine. This makes it possible to monitor intracerebral synthesis and uptake of dopamine by means of the positron-emitting 6-fluoro(18F)-L-3,4-dihydroxyphenylalanine (FDOPA), in conjunction with externally-placed devices suited for detection of annihilation photons, which progressively led to the most recent positron emission tomography (PET) units. Iasodopa, the commercial preparation of FDOPA that obtained a marketing authorisation in France in November 2006 (which is currently recognised by several other EU countries), is a solution for injection. The activity available at time of administration ranges from 0.1 GBq to 0.8 GBq per vial. The half-life of the radionuclide is 109.8 min with emission of positron radiation (Emax: 0.633 MeV) followed by photon annihilation radiations of 0.511 MeV. — NCATS