J Korean Soc Endocrinol.  1999 Mar;14(1):63-70.

Thallium-291 Whole Body Scintigraphy in Postoperative Follow-up of Differentiated Thyroid Carcinoma

• Kim ES
• Kim HK
• Lee SJ
• Ryu JS
• Moon DH
• Shong YK

Abstract

BACKGROUND
The advantages of thallium (Tl)-201 whole body scan in follow-up of patients with thyroid carcinoma include no need to discontinue thyroid hormone replacement, a shorter period of time between injection and imaging, a lower radiation dose, and preservation of affinity for subsequent therapeutic dose of 131I. To evaluate the reliability of whole body scintigraphy using Tl-201 in postoperative follow-up of thyroid carcinoma, this procedure was performed in patients after total thyroidectomy for thyroid carcinoma. The results were compared with those of 131I scintigraphy.
METHODS
One hundred nineteen cases (119 patients) with a median age of 43 years (range, 20 85 years) were included in the study. After optimal endogenous thyroid-stimulating hormone stimulation (>50 mIU/mL), 131I (4 mCi) scan and Tl 201 (3 mCi) scan were simultaneously performed. Concomitantly serum thyroglobulin and anti-thyroglobulin antibody levels were checked. If abnormal findings on any of the scintigraphic methods or high levels of thyroglobulin (> 10 ng/mL) were detected, high dose (150~200mCi) 131I was administered as therapy and then whole body scans were performed repeatedly after the therapy. The presence or absence of thyroid cancer was established by pathologic, radiologic, and/or high dose 131I scan findings.
RESULTS
In 12 patients, ll-201 scan revealed positive accumulations which were not found on 131I scan, of whom 9 had elevated thyroglobulin levels. In these cases, 5 cases were interpreted to have normal thyroid remnant and 7 cases showed pathologic findings (1 lung, 2 lymph node, 1 bone, and 2 lung and lymph node metastasis, and 1 false positive accumulation of thallium). Metastasis were confirmed histologically in 2 and radiologically in 5 cases. Negative Tl-201 scans, despite of positive 131I scans, occurred in 20 patients, of whom 6 had abnormal thyroglobulin levels. Seventeen cases were interpreted to have thyroid remnant, 2 cases were diagnosed to have thyroid carcinoma metastasis (1 lung, 1 lung and lymph node), and 1 case was not confumed.
CONCLUSION
These results suggest that 131I scan is superior to 11-201 scan for detection of residual or metastatic differentiated thyroid carcinoma. However, the use of combined modalities may provide a higher diagnostic yield. TI-201 scan can be useful especially in cases in which 'I scan is negative despite of abnormal thyroglobulin levels.

MeSH Terms

Follow-Up Studies*
Humans
Lung
Lymph Nodes
Neoplasm Metastasis
Radionuclide Imaging*
Thallium
Thyroglobulin
Thyroid Gland*
Thyroid Neoplasms*
Thyroidectomy
Thyrotropin
Whole Body Imaging
Thallium
Thyroglobulin
Thyrotropin