MEDULLARY-THYROID CARCINOMA IMAGED BY TC-99M MIBI SPECT AND TL-201 CHLORIDE TC-99M PERTECHNETATE SUBFRACTION SPECT

A 61-year-old man with medullary thyroid carcinoma and local invasion of the left lobe of the thyroid had Tc-99m MIBI SPECT and Tl-201 chlor ide/Tc-99m pertechnetate subtraction SPECT after left lobectomy of the thyroid, using a triple-headed gamma camera, Tl-201 chloride/Tc-99m p ertechnetate subtraction demonstrated a large mass with high Tl-201 up take in the left neck, Although there was intense uptake in the tumor in the left thyroid bed on Tc-99m MIBI neck SPECT, there was also upta ke in both salivary glands and the right lobe of the thyroid gland, Th us, uptake in the right lobe of the thyroid gland and the salivary gla nds might not be differentiated from tumor invasion or metastasis from medullary cell carcinoma, Compared with MIBI SPECT, Tl-201 chloride/T c-99m pertechnetate subtraction SPECT shows more apparent delineation of tumor uptake and may be a preferable technique.