Ultrasonography-guided Fine-needle Aspiration for Solid Thyroid Nodules Less than 5 mm in the Largest Diameter: Comparison in Diagnostic Adequacy and Accuracy According to Nodule Size.

Lee,  Jang Hee; Kim,  Dong Wook; Baek,  Seung Hun

Journal of Korean Society of Ultrasound in Medicine 2012;31(1): 17-21.

Jang Hee Lee, Dong Wook Kim, Seung Hun Baek

¹Department of Radiology, Busan Paik Hospital, Inje University College of Medicine, Korea. dwultra@lycos.co.kr
²Clinical Research Center, Busan Paik Hospital, Inje University College of Medicine, Korea.

Published online: March 26, 2012.

ABSTRACT

PURPOSE: This study assessed the adequacy and accuracy of ultrasonography (US)-guided fine-needle aspiration (US-FNA) of solid thyroid nodules, less than 5 mm in maximum diameter. MATERIALS AND METHODS: From January to December 2009, US-FNA was performed for small solid thyroid nodules in 201 patients. Each thyroid nodule was classified into group A and B according to the largest diameter (1 mm < or = group A < 3 mm and 3 mm < or = group B < 5 mm). The adequacy and accuracy of US-FNA in two groups were compared using the histopathological results as a reference standard. RESULTS: Of the 227 thyroid nodules in 201 patients, the inadequacy of US-FNA in group A and B was 24.3% (18/74) and 13.1% (20/153), respectively, showing a statistically significant difference between the two groups (p = 0.0333, chi-square test). Eighty nodules were removed surgically in 72 patients, from which papillary thyroid carcinoma (n = 52), follicular thyroid carcinoma (n = 1), nodular hyperplasia (n = 26), and pseudonodule related to thyroiditis (n = 1) were confirmed. Based on the histopathological results of the 80 surgical nodules, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of US-FNA in group A and B were 55.0% and 79.4%, 81.8% and 100%, 84.6% and 100%, 50% and 68.2%, and 64.5% and 85.7%, respectively. CONCLUSION: The adequacy and accuracy of US-FNA for solid thyroid nodules, > or = 3 mm in the largest diameter, were higher than those of US-FNA for very small nodules, < 3 mm in the largest diameter.

Keywords: Thyroid; Thyroid nodule; Biopsy, Fine-needle; Ultrasonography; Malignancy