Novel, substituted benzamides in radioiodinated form are useful in
radiopharmaceutical compositions in nuclear medicine as imaging agents to
detect, visualize, and analyze the distribution and function of the
dopamine D2 receptor in the mammalian brain. These compounds have a
specific combination of lipophilicity and dopamine D2 receptor affinity
required to attain a required image contrast. The iodinated benzamides
identified by the above discovery can be made by reacting a trialkyltin
substituted benzamide with an acid in the presence of radioactive iodine
which, in turn, is generated by in situ oxidation of an appropriate iodide
nuclide salt.