Whole-body Tc-99m sestamibi scintigraphy in the follow-up of differentiated thyroid carcinoma

Purpose: This study evaluated the potential of Tc-99m sestamibi whole-body scan (WBMIBI) as an alternative to whole-body I-131 scan (WBI) for the foll ow-up of patients with differentiated thyroid carcinoma. Materials and Methods: We evaluated 99 consecutive patients with differenti ated thyroid carcinoma who had total or nearly total thyroidectomy followed by an ablative dose of I-131 (86 women, 13 men; mean age, 44 +/- 12 years) . WBMIBI was performed and serum thyroglobulin (TG) levels were obtained at least 6 months after I-131 treatment. All persons were receiving levothyro xine therapy. Results: From the total of 110 studies performed, WBMIBI and TG were in agr eement in 96% and discordant in 4%, From the 27 crossed studies (WBMIBI x T G) with at least one abnormal result, 16 were compared with WBI. In four ca ses, the WBI did not reveal functioning thyroid tissue when both TG and WBM IBI indicated tumoral activity. In one case of pulmonary metastasis confirm ed by chest radiographs, with a normal TG value, the results of both WBMIBI and WBI were positive. Conclusions: WBMIBI should be considered as a scintigraphic method in the f ollow-up of differentiated thyroid carcinoma. This technique can show the s ites of tumoral activity with optimal image resolution, particularly in tho se with abnormal TG and negative WBI results, and it is a potentially valua ble tool in patients with anti-TG antibodies. The WBI in patients having ab lation should be reserved only for therapy planning.