PET imaging of dopaminergic system and clinical applications

AimDopamine is one of the major neurotransmitters of the central nervous system. Dopamine is involved in various cerebral and peripheral physiological functions and pathological conditions. The aim of this mini review is to overview the dopamine, PET radiotracers of dopaminergic system and their clinical applications.MethodsDopamine synthesis, dopamine receptors, role of dopamine in physiological functions and diseases, PET radiotracers of dopaminergic system and their clinical applications were reviewed.ResultsThere is a large number of PET radiotracers to assess various elements of dopaminergic system such as F-18 fluorodopamine to assess dopamine transfer and storage in peripheral catecholamine-synthesizing cells, F-18 FDOPA to assess L-DOPA transfer via l-amino acid transporters, conversion of L-DOPA to dopamine by aromatic l-amino acid decarboxylase and storage of dopamine at vesicles, C-11 methylphenidat, C-11 dihydrotetrabenazine, and C-11 deprenyl to assess dopamine transport via dopamine transporters, dopamine transport into vesicles by vesicular monoamine transporter-2, and dopamine degredation by monoamine oxidase, respectively, in presynaptic dopaminergic nerve terminals in the brain and in certain peripheral cells and C-11 raclopride and C-11 SCH 23,390 to assess dopamine receptors at postsynaptic nerve terminals. Among these radiotracers, only F-18 FDOPA is widely and commercially available. The other radiotracers are available in limited centers, mainly for research purpose. Dopaminergic PET radiotracers help to detect or diagnose various diseases such as parkinsonian syndromes, huntington's disease, dementias, schizophrenia, drug addictions, paragangliomas, pheochromocytoma, medullary thyroid carcinoma, gut carcinoids, gliomas and hyperinsulinemic hypoglycemia.ConclusionThere is a large number of dopaminergic PET radiotracers which help to detect or diagnose diseases of the various systems in which dopaminergic system is involved.