Role of thyroid ultrasound in the diagnostic evaluation of thyroid nodules.

Thyroid ultrasound (US) features associated with malignancy in thyroid nodules are microcalcifications, hypoechogenicity, irregular margins or absent halo sign, solid aspect, intranodular vascularization, and shape (taller than wide).These patterns, taken singly, are poorly predictive. When they are simultaneously present the specificity increases at the expense of sensitivity. US elastography (USE) is a powerful new diagnostic tool that assesses hardness as an indicator of malignancy in thyroid nodules. USE has high specificity and sensitivity independent of the nodule size, and this predictive value is maintained in follicular lesions. Available data suggest that USE is the best available non-invasive tool comparable to fine-needle aspiration (FNA) for the evaluation of thyroid nodules, provided that the nodule is solid and devoid of coarse calcifications. Thus, conventional US retains its importance for selecting nodules in which USE is predictive. In conclusion, USE has great potential as a new tool for the diagnosis of thyroid cancer, especially in nodules with indeterminate cytology.