Ultrasonic Features of Thyroid Cancers and Benign Thyroid Nodules for Determining the Necessity of Fine Needle Aspiration Cytology

The convenience and non-invasiveness of thyroid ultrasonography have made it the first choice for initial assessment of thyroid nodules. Fine-needle aspiration cytology (FNAC) is usually performed immediately after observation by ultrasonography or under its guidance. Quick staining methods have enabled a diagnosis of the nature of thyroid nodules within minutes. However, in cases where many nodules are present at the same time, it can be unclear as to which one to pick for FNAC. When a nodule is suspected to be malignant, FNAC is also needed. If clinicians can accurately identify with ultrasonography the characteristics of thyroid nodules with high risks of malignancy or benignity, there would be a faster and more accurate determination of whether FNAC is required, thereby leading to a faster and more accurate diagnosis or rule-out of thyroid cancers and a potential decrease in the burden of healthcare and other costs. The present review identifies these characteristics so that results of thyroid ultrasonography can be maximized and FNAC only used when necessary.