Sonographic criteria for fine-needle aspiration cytology in a Korean female population undergoing thyroid ultrasound screening

Abstract

Background: Thyroid sonography is commonly used as a screening procedure resulting in finding of innumerable benign nodules. It would be necessary to apply strict sonographic criteria for incidentally detected thyroid nodules to avoid unnecessary invasive procedures or further examinations.

Purpose: To prospectively evaluate the incidence of diverse thyroid lesions including thyroid cancer detected during thyroid ultrasound (US), and to establish the diagnostic value of sonographic criteria for thyroid nodules.

Material and methods: During 2 years, 2250 patients visited the breast clinic for a breast US examination. In 2079 of these women (mean age 42.6 years, age range 15-77 years) without a history of previous thyroid surgery or thyroid abnormalities, thyroid screening with US was performed as well. The overall findings of all thyroid lesions detected during thyroid US were recorded. Fine-needle aspiration (FNA) was performed for all suspicious thyroid lesions and some with probably benign findings. The sonographic features of 113 aspirated nodules were analyzed and classified as either positive or negative findings. Sonographic classifications were correlated with the histological findings. The diagnostic index was calculated for individual sonographic criteria.

Results: Of the 2079 patients, 1209 patients (58%) had normal findings. Abnormal findings (42%) included thyroid cancer (n=53, 2.5%), solid nodules except for thyroid cancer (n=300, 14.4%), mixed echoic nodules (n=112, 5.4%), cysts (n=294, 14%), thyroiditis features without thyroid nodules (n=106, 5.1%), and parenchymal calcifications (n=5, 0.2%). Of 113 aspirated nodules, 80 nodules were classified as positive and 33 nodules as negative according to the sonographic criteria in a retrospective analysis. Of 80 lesions classified as positive, 51 lesions were malignant. Of 33 lesions classified as negative, 2 lesions were malignant. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 96.2%, 51.7%, 63.8%, 93.9%, and 72.6%, respectively.

Conclusion: Thyroid abnormalities were detected in 42% of all screened women. The use of the sonographic criteria showed excellent diagnostic performance for FNA and could be useful to provide practitioners with an objective tool to decide whether to perform a biopsy or not.