Localization of metastases from medullary thyroid carcinoma using different methods.

We analyzed the efficiency of three different noninvasive methods in the localization of recurrent medullary thyroid carcinoma (MTC). Nine patients (six females and three males) with biochemical evidence of disease after primary surgery were subjected to 131I anti-carcinoembryonic antigen (anti-CEA) antibody, 131I meta-iodo-benzylguanidine (MIBG), and computed tomography. Another female patient, in biochemical remission for six years after initial surgery, was also studied using the same methods. Three of the ten patients had negative results with all three methods (including the patient in remission). The other seven patients showed abnormal uptake of labeled anti-CEA antibody in various localizations; only two of these patients had a corresponding pathological image by computed tomography and only one by 131I MIBG. These preliminary results suggest that 131I anti-CEA scanning may be the most sensitive noninvasive method for the localization of MTC recurrences.