Background: Although ultrasonographic (US) evaluation is currently recommended for the workup of all palpable thyroid nodules, little guidance exists regarding the manner in which US data are to be used. Herein, we examine the available evidence and recommend how US can be used most effectively to predict malignancy. We discuss the role of US-guided fine needle aspiration (FNA) and other special topics regarding US evaluation and management of benign nodules.
Methods: We also present a systematic review of the literature using evidence-based criteria.
Results: US features alone cannot predict malignancy or benignity, but techniques that combine US features and FNA cytology are most effective and most accurate for predicting malignancy (Level III and IV evidence). US features suggesting malignancy include a blurred or ill-defined margin, irregular shape, solid echo structure, hypoechogenicity, absent halo, fine calcifications, and intranodular vascular pattern. Most patients with malignancies have more than two US features characteristic of malignancy. US-guided FNA has nonsignificantly higher sensitivity, specificity, and accuracy than the palpation-guided technique (Level III and IV evidence). US guidance is particularly beneficial in patients with nonpalpable, multiple, or heterogeneous nodules for preferentially aspirating a specific segment of the nodule (large or partially cystic nodule) or when nodule palpation is difficult (patients with diffuse glandular disease or obesity).
Conclusions: US is an essential component of thyroid nodule evaluation and management. Techniques that combine US features and FNA cytology for thyroid nodule workup are more accurate than either technique alone. US-guided FNA can decrease the rate of nondiagnostic aspirates.