New radionuclide tracers for the diagnosis and therapy of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC), a calcitonin-producing tumor that occurs in familial and sporadic forms, can be monitored satisfactorily with measurements of calcitonin and CEA in serum. However, locating the tumor site may be difficult. In the current review of the experience with four new radionuclide tracers for MTC, the relative value of each of these procedures is outlined. Total body imaging using TI-201 chloride and Tc-99m(V) DMSA are both sensitive techniques that can be used for the detection and follow-up of MTC. Imaging using I-131 MIBG and I-131 anti-CEA antibodies/fragments should be performed once the diagnosis and the tumor site have been established, to evaluate if patients might be amenable for therapy with one of these radiopharmaceuticals.