Ultrasound for the assessment of thyroid nodules: an overview for non-radiologists

Upon discovery of a thyroid nodule (or nodules), a patient is usually referred for evaluation by ultrasound, which is typically performed by a trained radiologist or sonographer. More recently, this technology has been used intraoperatively by endocrine surgeons and also by endocrinologists, often in the context of 'one-stop shops' or point of care ultrasound in the outpatient setting. Although thyroid nodules are common and most will be benign, the subsequent work up of these can cause anxiety for patients and place a burden on radiologists. In the UK, sonographic features of benign, suspicious or malignant nodules are classified by the British Thyroid Association U1-U5 criteria, which decide whether to biopsy the nodule (typically U3 and above). This article provides an overview of ultrasound in assessing the thyroid nodule in the context of this classification. This can be used as a guide to interpretation of thyroid ultrasonography for non-radiologists.