Figure 7. [18F]-DTBZ

Imaging the type 2 vesicular monoamine transporter (VMAT) in the brain provides a measurement reflecting the integrity of all three monoaminergic neurons

VMAT2 is a relatively unspecific transporter, as it functions to move a wide variety of amines into the vesicle lumen, including dopamine, serotonin, norepinephrine, histamine, and a number of structurally related molecules.

Dopamine is a simple organic chemical that functions as a neurotransmitter in the brain. As part of the reward pathway, dopamine is manufactured in nerve cell bodies located within the ventral tegmental area and is released in the nucleus accumbens and the prefrontal cortex. The motor functions of dopamine are linked to a separate pathway, with cell bodies in the substantia nigra that manufacture and release dopa-mine into the striatum. Dopamine is transported to the synaptic sites and packaged into vesicles for release, which occurs during synaptic transmission. Following release of dopamine into the synapse, dopamine interacts with postsynaptic dopamine recep-tor sites. Free dopamine in the synapse is also reabsorbed into the presynaptic terminal via dopamine transporter.

α[11C]Dihydrotetrabenazine (DTBZ) is a stable, stereoselective tracer which binds selectively to VMAT 2 and is less regulated by intrasynaptic dopamine than are other dopaminergic tracers. 18F-DTBZ, gives the highest specific signal in the assessment of presynaptic neuronal degeneration.

- Sabba L. Imaging in Neurodegenerative Disorders; Oxford University Press; first edition, 2015,  UK, pp: 164-167