The overall objective of this project is to synthesize radiolabeled androgen derivatives which are capable of mapping the distribution of androgen receptors in vivo. This will be achieved by covalently binding a radionuclide containing moiety such as a chelate for the radioactive metals or a phenol or imidazole for iodine to an androgen. These androgen derivatives may facilitate the detection of androgen dependent tumors by non invasive means. The goal set for the current year is to synthesize a derivative of dihydrotestosterone and teestosterone using an iodo tyrosine methyl amide of succinic acid. The second acid group of the succinic acid will be bound to the 17-OH of the dihydrotestosterone or testosterone by the reaction of succinic anhydride. The distribution of this radiolabeled derivative is to be studied in Sprague Dawley rats. BIBLIOGRAPHIC REFERENCES: Grove R.B., Reba R.C., Eckelman W.C.: Clinical Evaluation of Radiolabeled Bleomycin for Tumor Detection. J. Nucl. Med. 15:386-390, 1974. Reba R.C., Eckelman W.C., Poulose K.P. et al: The Search for Tumor Specific Radiopharmaceuticals: Radiolabeled Bleomycin. Radiopharmaceuticals. Ed. M. Subramanian. Society of Nuclear Medicine. 1975.