99mTc-DMSA (V) in detection of metastases of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare thyroid cancer secreting calcitonin (CT) which is the most sensitive and specific tumor marker for MTC. This type of thyroid cancer is able to metastasize to different body areas including regional lymph nodes, lungs, liver and bone. The aim of this study was to assess the sensitivity and specificity of [99mTc-DMSA (V)] whole body scan (WBS) in detection of metastases in MTC. This descriptive and prospective study was performed in 15 patients with MTC referred to our nuclear medicine centre since 2004 to 2005. These patients were compared regarding age, sex, and duration of the disease. Sensitivity and specificity of each diagnostic modality in detection of metastases were calculated and compared statistically. [99mTc-DMSA (V)] showed 91% sensitivity and 75% specificity as compared with serum calcitonin as gold standard. The figures for CT scan were 82% and 45%, respectively. CEA showed 64% sensitivity and 50% specificity. It is concluded that despite the slightly lower sensitivity and specificity of [99mTc-DMSA (V)] as compared to calcitonin (Gold-standard method), this radiotracer can be used for identification of recurrence or metastasis of medullary thyroid carcinoma.