Radiobrominated m-tyrosine analog as potential CNS L-dopa pet tracer.

Radiobrominated 6-bromo-m-tyrosine (6-BMT) was prepared and the time course of its localization in selected cerebral and peripheral organs in the mouse was determined. Since m-tyrosine is known to have L-dopa-like properties in vivo, our goal was to assess the utility of a radiolabeled analog as a tracer for cerebral L-dopa. Our preliminary results showed that substantial amounts of 6-BMT is extracted by the mouse brain and that the regional distribution and time course of the radiotracer is consistent with uptake in regions rich in dopamine neurons. Although a more thorough biochemical characterization of 6-BMT is necessary, this or other positron emitting analogs of m-tyrosine, such as an 18F labelled analog, may be useful PET tracers for the non-invasive study of dopamine turnover in humans.