Journal of Korean Endocrine Society 1999;14(2):339-345.
Published online January 1, 2001.
A Comparison Technetium-99m and Iodine-123 Scan in Thyroid Hot Nodules.
Eun Sook Kim, Seok Jun Hong, Young Ki Song, Jin Sook Ryu, Dae Hyuk Moon, Ki Soo Kim
Pertechnetate ( Tc) has been widely employed for thyroid imaging. While pertechnetate and radioiodide have usually similar results in identifying thyroid nodules, occasionally differences have been noted. We intended to observe that the thyroid nodules which appeared to be hot on pertechnetate and to compare them with the images by radioiodide. METHODS: 'I scan was performed to thirty-eight cases (mean age: 48.9 +/- 13.2) presenting as hot nodule on Tc scan. Thyroid function test and pathologic diagnosis were obtained in all patients. RESULTS: Of the 38 patients, 24 had euthyroidism, 13 had hyperthyroidism, and 1 had hypothyroidism. Thirty patients had adenomatous goiter, 4 papillary carcinoma, 3 Hashimotos thyroiditis, and 1 had HQrthle cell tumor. 28 of 38 patients showed similar images, but the remaining 10 patients(26.3%) revealed discordant images on Tc and 131I scan. Among the concordant cases, 23 had adenomatous goiter, 3 had papillary carcinoma, and 2 had Hashimotos thyroiditis. Among the discordant cases, 7 had adenomatous goiter, 1 had papillary carcinoma, 1 had Hashimotos thyroiditis, and 1 had HQrthle cell tumor. The incidence of malignancy was 10.7% of concordant cases, and 20% of discordant cases and was revealed statistically insignificant (p>0.05). CONCLUSION: We observed higher incidence of malignancy in patients presenting hot nodules on 99mTc scan than ever reported. Fine needle aspiration should be performed to all patients with hot nodules and the 'I scan would not be recommended for further diagnostic study.
Key Words: Thyroid hot nodule, Technetium-99m scan, Jodine-123 scan

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