Tc-99m sestamibi and other agents in the detection of metastatic medullary carcinoma of the thyroid.

The 10-year survival rate for medullary carcinoma of the thyroid (MCT) is 50%; thus, good tumor-seeking radiopharmaceuticals are needed to localize foci of recurrence and metastasis during follow-up. Two patients with metastatic MCT were studied with Tl-201, I-131 MIBG, Tc-99m (V)-DMSA, and Tc-99m MIBI. A SPECT study with the latter agent allowed the visualization and precise localization of a metastatic mediastinal lymph node. More studies need to be done to evaluate the role of Tc-99m MIBI in the detection of recurrence and metastases of MCT.