What imaging modalities are used for thyroid nodule confirmation?

From the Guidelines

For thyroid nodule confirmation, ultrasound is the recommended first-line imaging modality, as it provides detailed information about nodule characteristics without radiation exposure, and helps differentiate benign from potentially malignant nodules, as supported by the American College of Radiology Appropriateness Criteria 1. The ultrasound examination should include:

• Grayscale imaging of the entire thyroid gland
• Color Doppler assessment of nodule vascularity
• Measurement of nodule dimensions in three planes
• Evaluation of cervical lymph nodes Key ultrasound features to assess include:

• Nodule composition (solid, cystic, or mixed)
• Echogenicity (hypoechoic, isoechoic, or hyperechoic)
• Margins (regular or irregular)
• Presence of microcalcifications
• Shape (taller-than-wide)
• Vascularity pattern Ultrasound is preferred because it provides detailed information about nodule characteristics without radiation exposure, and helps guide decision-making for further management, such as fine-needle aspiration biopsy, as noted in the ESMO clinical recommendations for diagnosis, treatment, and follow-up of differentiated thyroid cancer 1. In cases where ultrasound results are inconclusive or additional information is needed, other imaging modalities like CT or MRI may be considered, but these are not routine first-line tests for thyroid nodule evaluation, as stated in the ACR Appropriateness Criteria 1.

From the Research

Imaging Modalities for Thyroid Nodule Confirmation

The following imaging modalities are used for thyroid nodule confirmation:

• Ultrasonography (US) is the most commonly used imaging modality for characterization of thyroid nodules 2, 3, 4
• Computed tomography (CT) and magnetic resonance imaging (MRI) are also used, although less commonly 2
• Positron emission tomography (PET) is used in some cases, particularly for evaluation of metabolically active nodules 2
• Nuclear scintigraphy is used for evaluation of physiologic thyroid function and identification of metabolically active and inactive nodules 2

Characteristics of Malignant Thyroid Nodules

The following characteristics are associated with an increased likelihood of malignancy in thyroid nodules:

• Microcalcifications 2, 5, 6
• Solid composition 2
• Central vascularity 2
• Taller-than-wide shape 5, 6
• Ill-defined contour 5
• Presence of a halo 5
• Adenopathy 5

Biopsy Techniques

The following biopsy techniques are used for thyroid nodule confirmation:

• Fine-needle aspiration biopsy (FNAB) 2, 5, 4
• Core biopsy, which is indicated following nondiagnostic or indeterminate FNAB 2
• Ultrasound-guided biopsy technique, which is crucial for making the diagnosis 2, 3, 4