Datscan is a solution of<unk> (123I) for injection into a living test subject. The iodine introduced during manufacture is a radioactive isotope, iodine-123, and it is the gamma decay of this isotope that is detectable to a gamma camera. 123I has a half-life of approximately 13 hours and a gamma photon energy of 159 keV making it an appropriate radionuclide for medical imaging. The solution also contains 5% ethanol to aid solubility and is supplied sterile since it is intended for intravenous use.<unk> has a high binding affinity for presynaptic dopamine transporters (DAT) in the brains of mammals, in particular the striatal region of the brain. A feature of Parkinson's disease is a marked reduction in dopaminergic neurons in the striatal region. By introducing an agent that binds to the dopamine transporters a quantitative measure and spatial distribution of the transporters can be obtained.
Ioflupane 
Enoximone
Norethisterone
Cabergoline
5α-Dihydronorethisterone
Clobetasone
Nandrolone phenylpropionate
Promestriene