Ultrasonography and fine-needle aspiration cytology of thyroid nodules: assessment of malignancy using the British Thyroid Association classification

Abstract

Background

The widespread use of high-resolution ultrasonography (US) imaging has led to an increased detection of thyroid nodules, which are common in the general population.

Purpose

To evaluate the correlation between ultrasonographic and pathological findings of thyroid nodules undergoing US-guided fine-needle aspiration (FNA) and assess the contribution of US features to malignancy prediction.

Material and Methods

A total of 573 patients (137 men, 436 women; age range = 20–88 years) who underwent US-guided FNA were included. Nodule characteristics were recorded using the British Thyroid Association (BTA) U classification, and cytological results were assessed according to the Bethesda system. Logistic regression analysis (LRA) was performed to determine the relationship between US features and malignancy.

Results

The distribution of nodules in U2, U3, U4, and U5 categories was 212, 171, 84, and 36, respectively, with corresponding Bethesda (2–6) classifications of 287, 159, 18, 27, and 12. Malignancy rates (Bethesda 4–6) were 0%, 10%, 28.6%, and 44.5%, respectively. Hypoechogenicity (relative to muscle), internal vascularization, and microcalcifications were significantly associated with malignancy (P <0.05). LRA achieved an 85.5% accuracy in malignancy prediction.

Conclusion

US features in the BTA U classification align with pathological findings. Hypoechoic solid nodules, central vascularization, and microcalcifications should raise suspicion for malignancy in the differential diagnosis of thyroid nodules. These study findings highlight the strong association between vascularity in the BTA classification and malignancy, suggesting its potential role in risk stratification.