Nuclear endocrinology as a monitoring tool.

Malignant endocrine disorders have been an enigma over the last few decades, from genetic, clinical, and imaging perspectives. The detection of the primary tumor and the identification of recurrent disease have been essentially based on various anatomic techniques, with localization procedures extensively developed for staging, follow-up, radio-guided surgery, and therapy. Frequently, the lesions are too small to cause anatomic alterations, or they are obscured by the changes in anatomic planes that occur after initial surgery. Small lesions, however, are the ones that can potentially be cured. Thus, every attempt should be made to localize these sites before further growth and dissemination occur beyond the scope of cure. Since the advent of iodine-131 for staging and follow-up of patients with differentiated thyroid carcinoma, the search has led to the use of radioiodinated metaiodobenzylguanidine (MIBG) for recurrent pheochromocytoma and neuroblastoma, to the development of antibodies to carcinoembryonic antigen for the staging and treatment of medullary thyroid carcinoma, and to the characterization of peptide receptors on neuroendocrine tumors. Additionally, there has been a breakthrough with the use of positron emitters in nuclear oncology, including F-18-fluorodeoxyglucose, for I-131-negative metastases of differentiated thyroid carcinoma, recurrent medullary thyroid carcinoma, malignant pheochromocytoma, and adrenocortical carcinoma. Undoubtedly, optimal care of the patient requires both the expertise of the treating endocrinologist and the use of various imaging techniques in the diagnosis, staging, and follow-up of these diseases.