Evaluating Thyroid Nodules: The Roles of Sonography and Nuclear Medicine

George Tsoukatos, BPS, R.T. (R)(ARRT)®*

^*Medical Imaging Consultant, Germantown, NY

Address correspondence to: George Tsoukatos, BPS, R.T. (R)(ARRT)^®*, Radiology Support Services, PO Box 215, Germantown, NY 12526. E-mail: radiologytechnique@gmail.com.

Disclosure Statement: The author reports having no significant financial or advisory relationships with corporate organizations related to this activity.

ABSTRACT

Thyroid nodules (TNs) are common in the general patient population and in clinical primary care settings and are considered to be one of the most common endocrine system abnormalities. TNs are discrete lesions that can be radiologically and pathologically differentiated from normal thyroid parenchyma. Distinguishing a benign from a malignant nodule can be challenging, and professional guidelines have assisted with standardizing their evaluation, management, and follow-up procedures. Thyroid ultrasound (TUS) is easily accessible, noninvasive, and cost-effective, and is a key imaging study for diagnosing and managing patients with TNs. TUS can also assess the patient for malignancy risk, ultimately determining if a nodule requires biopsy. Adjunct TUS techniques such as color Doppler, 3-dimensional (3D) sonography, elastography, and contrast enhancement may also assist with a patient's workup. Nuclear medicine and imaging can also play a part in managing patients with TNs, specifically with radioactive iodine uptake/thyroid uptake and thyroid scintigraphy, both of which allow more detailed evaluation. This course will review the anatomy of the thyroid, outline risk factors for developing thyroid cancer, as well as the types and stages of thyroid cancer. Sonographic imaging techniques used in managing patients with TNs will be described, including 3D sonography, color Doppler, elastography, and contrast-enhanced sonography as well as circumstances that would warrant TN biopsy. Fine-needle aspiration biopsy equipment, patient management, and procedures will be reviewed. Finally, a discussion of the basic concepts of nuclear imaging and techniques commonly used in thyroid imaging, including scintigraphy, radioactive iodine uptake procedures, radiotracers, radiotracer administration and dosing, and uptake calculations will also be detailed. Pictorial examples of TNs in various stages, in all discussed modalities, are included.