Objective: We analyzed the sonographic characteristics of thyroid nodules and assessed the diagnostic value of ultrasonography in order to distinguish between benign and malignant lesions in terms of the management of thyroid nodules.
Design: We retrospectively analyzed the sonographic features of thyroid nodules in 580 patients who had been examined with fine-needle aspiration cytology or who underwent surgery for a thyroid nodule. The sonographic features that suggested malignancy include microcalcifications, an irregular or microlobulated margin, marked hypoechogenicity, and a shape that was taller than it was wide. The presence of one or more of these features indicated classification as category 3 (malignant). The absence of all of these features indicated classification as category 2 (benign). Presence of an anechogenic cystic nodule was classified as category 1 (benign).
Main outcome: Of 124 lesions classified as category 3, 60 of the lesions were malignant. Of 418 lesions classified as category 1 or 2, 409 were benign. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy based on the sonographic classification method were 87.0%, 86.5%, 48.4%, 97.8%, and 86.5%, respectively.
Conclusions: Our results identified this sonographic classification as a useful tool in the differentiation of malignant nodules from benign nodules. In view of the high negative predictive value of sonographic classification, a more aggressive approach is recommended only for category 3 nodules.