Ultrasound Evaluation of Thyroid Nodules: A Review

Neck ultrasound is the first line imaging tool for evaluating a thyroid nodule because of its ability to demonstrate multiple aspects of a lesion and also lack of invasiveness with high sensitivity. Clinicians utilize abstract data including gray-scale imaging (echogenicity, margin & calcification structure), Doppler assessment (blood supply and resistive index reported) for blood supply evaluation, and risk stratification systems such as ACR TI-RADS, EU-TIRADS or ATA guidelines to assist in the diagnosis of sonographically detected thyroid tumor lesions. This narrative review is based on the evolution of the literature related to thyroid ultrasound imaging and diagnosis. This cohort study shows that among patients undergoing cytology for ultrasound characteristics, the normalization of ultrasound characteristics and risk factor assessment improve the accuracy of diagnosing specific cancerous lesions and help avoid unnecessary biopsies. Although vascular information is contained within the Doppler ultrasound, elastography and CEUS are functional/perfusion imaging techniques that provide additional characterization of the lesion. FNA remains essential in establishing a definitive diagnosis, particularly in patients with indeterminate or high-risk nodules. Thyroid scintigraphy is a major component in the assessment of thyroid nodules. The other non-invasive methods are used to clarify the diagnosis, and determine which patients need minimal invasive procedures.