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 the nodule's size, composition, and characteristics that may suggest malignancy, and is non-invasive, widely available, and does not use ionizing radiation 1. The following are the key points to consider when using ultrasound for thyroid nodule confirmation:

• Ultrasound should be performed as soon as a nodule is suspected or palpated during physical examination.
• The ultrasound should be performed by an experienced sonographer or radiologist using a high-frequency linear transducer (typically 7-15 MHz).
• Both transverse and longitudinal views of the thyroid gland should be obtained, with measurements of any nodules in three dimensions.
• If ultrasound reveals suspicious features or the nodule is larger than 1-1.5 cm, a fine-needle aspiration (FNA) biopsy should be performed under ultrasound guidance for definitive diagnosis. Some of the key features that may suggest malignancy on ultrasound include:
• Irregular margins
• Hypoechogenicity
• Microcalcifications
• Increased vascularity Other imaging modalities like CT or MRI are generally not necessary for initial evaluation of thyroid nodules, but may be considered in specific cases, such as evaluating for retrosternal extension of a large goiter or assessing regional lymph nodes in known thyroid cancer 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, 5
• Computed tomography (CT) is used for incidental detection of thyroid nodules 2
• Magnetic resonance imaging (MRI) is used for incidental detection of thyroid nodules 2
• Positron emission tomography (PET) is used for incidental detection of thyroid 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 US characteristics increase the likelihood of malignancy in a thyroid nodule:

• Microcalcifications 2, 3, 4
• Solid composition 2, 3
• Central vascularity 2
• Taller-than-wide shape 3, 4
• Ill-defined margins 3, 4
• Intranodular vascularity 3
• Macrocalcification 3
• Hypoechogenicity 3
• Presence of a peripheral halo 4
• Adenopathy 4

Biopsy Techniques

The following biopsy techniques are used for thyroid nodule confirmation:

• Fine-needle aspiration biopsy (FNAB) 2, 3, 4, 6
• Core biopsy 2
• Ultrasound-guided fine-needle aspiration biopsy 5, 6