Role of thallium-201 total-body scintigraphy in follow-up of thyroid carcinoma.

To evaluate the reliability of total-body scintigraphy using [201Tl]chloride in postoperative follow-up of thyroid carcinoma, this procedure was performed in 326 patients after total thyroidectomy for thyroid carcinoma. The results were compared with those of 131I scintigraphy and thyroglobulin assays. 201Tl total-body scintigraphy was found to have the greatest sensitivity (94%), whereas 131I scintigraphy had the highest specificity (99%). It is shown that 201Tl total-body scintigraphy is a useful procedure in follow-up of thyroid cancer, however, the combination of parameters provides the greatest reliability. In medullary thyroid carcinoma, which is usually 131I negative, 201Tl total-body scintigraphy can be of great value for the localization of metastases which are indicated by elevated serum levels of calcitonin and carcinoembryonic antigen.