Ovarian imaging by the binding of radioiodinated chorionic gonadotropin: concise communication.

Previous studies have demonstrated the presence of specific, high-affinity receptors for human chorionic gonadotropin (HCG) in human and rat ovaries. In the present study, highly purified HCG was labeled with iodine-131 and used for the imaging of luteinized rat ovaries. Excellent images were obtained. The accumulation of radioactivity in the ovaries was completely inhibited by previous administration of excess unlabeled HCG. Time-course studies show that radioiodinated HCG was rapidly accumulated within 1 hr and largely cleared from the ovary at 24 hr. These results show the potential for imaging of endocrine target tissues by hormone-receptor binding, and the possibility of quantitation of hormone receptors in tissues under pathological conditions.