Biopsy of thyroid nodules: comparison of three sets of guidelines

The purpose of this study was to compare the results with three sets of guidelines for fine-needle aspiration biopsy of thyroid nodules.

A total of 1,398 nodules confirmed with fine-needle aspiration biopsy or surgery were included in the study. We compared the diagnostic value of three sets of guidelines for ultrasound findings that should lead to fine-needle aspiration biopsy of a nodule. According to the Kim criteria, a nodule should have at least one of the following findings: marked hypoechogenicity, irregular or microlobulated margins, microcalcifications, or length greater than width. According to the Society of Radiologists in Ultrasound, biopsy should be performed on a nodule 1 cm in diameter or larger with microcalcifications, 1.5 cm in diameter or larger that is solid or has coarse calcifications, and 2 cm in diameter or larger that has mixed solid and cystic components, and a nodule that has undergone substantial growth or is associated with abnormal cervical lymph nodes. According to the American Association of Clinical Endocrinologists, a hypoechoic nodule with at least one additional feature, such as irregular margins, length greater than width, and microcalcifications, should be biopsied.

For all nodules, the diagnostic accuracy of the Kim (area under the receiver operating characteristic curve [Az]=0.868) and American Association of Clinical Endocrinologists (Az=0.850) criteria was greater than that of the Society of Radiologists in Ultrasound criteria (Az=0.551). The number of nodules for which fine-needle aspiration biopsy was recommended (25.6%) was smallest with use of the American Association of Clinical Endocrinologists criteria, and the smallest number (7.3%) of missed malignant lesions was associated with use of the Kim criteria. The results did not change for the subgroup with nodules larger than 1 cm.

The Kim and American Association of Clinical Endocrinologists criteria are more accurate than the Society of Radiologists in Ultrasound criteria. The American Association of Clinical Endocrinologists guidelines are recommended for achieving high specificity, and the Kim criteria may be chosen for higher sensitivity.