Scintigraphy with 201Tl for detection of thyroid cancer metastases.

In four patients with disseminated papillary or follicular thyroid carcinoma metastatic sites could be demonstrated by scintigraphy with 201Tl. Uptake was present during TSH suppression with thyroid hormone administration. In three of the four cases 201Tl scanning revealed metastases while 131I uptake after triiodothyronine withdrawal was absent. In one patient 201Tl demonstrated some metastatic sites while both 131I uptake and thyroglobulin levels were negative. Uptake of 201Tl in these metastases is at least partially, unrelated to the TSH and thyroglobulin levels or to the 131I-accumulating capacity. Scintigraphy using 201Tl might be helpful for the detection of metastatic thyroid carcinoma in those cases where 131I uptake is absent.