A diagnostic formulation is provided comprising a tropane having a radioactive concentration of at least 1.6 mCi/mL at least about 51 hours post creation. The diagnostic formulation optionally comprises a radiolabeled dopamine transporter (DAT) ligand useful in the diagnosis of Parkinsons disease (PS). One example of a radiolabeled dopamine transporter (DAT) ligand example is [123I]-N-(3-iodoprop-2E-enyl)-2β-carbomethoxy-3β-(4-methylphenyl) nortropane.
