Journal of Korean Endocrine Society 2001;16(4-5):447-456.
Published online October 1, 2001.
Usefulness of Thallium-201 Scintigraphy for Differentiating Benign and Malignant Thyroid Nodules in Inconclusive Cases with Fine Needle Aspiration.
Young Sil Lee, Chang Won Lee, Mi Hwa Jang, Ju Won Seok, Seok Man Son, Seok Dong Yoo, In Joo Kim, Yong Ki Kim
1Department of Internal Medicine, Pusan National University, Collage of Medicine, Pusan, Korea.
2Department of Nuclear Medicine, Pusan National University, Collage of Medicine, Pusan, Korea.
3Department of Internal Medicine, Collage of Medicine, DongGuk University, Kyeongju, Korea.
Although fine needle aspiration(FNA) is recognized as the most accurate procedure in the differential diagnosis of thyroid nodules, about 20~30% of nodules remain inconclusive in FNA. Therefore, we assessed the usefulness of Thallium-201 scintigraphy in differentiating benign from malignant thyroid nodules in patients with inconclusive diagnosis by FNA. METHODS: We studied 43 patients with inconclusive diagnosis(29 of follicular neoplasm, 11 of cystic change and 3 of inadequate) by FNA, with the results being confirmed histopathologically by operation. Thallium-201 scintigraphy was performed at 15 minutes(early scan) and 2-3 hours(late scan) after the intravenous administration of 37 MBq of thallium-201. Malignant nodules were defined by the retention of Thallium-201 on delayed images. RESULTS: In the 43 patients with inconclusive FNA diagnosis, Thallium-201 scan had a sensitivity of 75.0%, specificity of 62.9% and accuracy of 65.1%. The positive and negative predictive values were 31.6% and 91.7%, respectively. In the 29 patients with follicular neoplasm by FNA, Thallium-201 scan had a sensitivity of 83.3%, specificity of 60.9% and accuracy of 65.5%. The positive and negative predictive values were 35.7% and 93.3%, respectively. CONCLUSION: In particular, Thallium-201 scintigraphy demonstrated a high negative predictive value, Therefore, for patients with inconclusive FNA findings, Thallium-201 scintigraphy might be useful in differentiating between benign and malignant thyroid nodules, and has the potential to reduce the rate of unnecessary operations in benign nodules.
Key Words: Thallium-201 scintigraphy, Inconclusive group, Fine needle aspiration(FNA), Thyroid nodules
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