From the Guidelines
When evaluating thyroid ultrasound in a person with goiter, the key characteristics to consider include nodule size, composition, echogenicity, margins, presence of calcifications, vascularity patterns, and extracapsular extension, as these features help differentiate between benign and potentially malignant nodules 1. The ultrasound should examine the overall thyroid gland size, symmetry, and parenchymal echogenicity, as well as assess lymph nodes in the neck for abnormal enlargement or suspicious features. Some of the key characteristics to assess in thyroid ultrasound for a person with goiter are:
- Nodule size and number
- Composition (solid, cystic, or mixed)
- Echogenicity (hypoechoic, isoechoic, or hyperechoic compared to normal thyroid tissue)
- Margins (regular vs. irregular)
- Presence of calcifications (microcalcifications are concerning for malignancy)
- Vascularity patterns
- Extracapsular extension These characteristics are crucial in guiding clinical management decisions, including whether fine needle aspiration biopsy is needed, which is typically recommended for nodules larger than 1-1.5 cm with suspicious features or for smaller nodules with highly suspicious characteristics, as suggested by the American College of Radiology 1. The presence of suspicious features such as hypoechoic solid nodules, irregular margins, microcalcifications, taller-than-wide shape, and abnormal vascularity warrant further investigation, and molecular testing for thyroid nodules (BRAF, RAS, RET/PTC and PAX8/PPARγ mutations) can be a strong indicator of cancer, with approximately 97% of mutation-positive nodules having a malignant diagnosis at histology 1.
From the Research
Characteristics to Consider in Thyroid Ultrasound
In a person with goiter, the following characteristics should be considered in thyroid ultrasound:
- Thyroid size and volume, as measured by ultrasound, can be used to estimate the size of the goiter 2
- Ultrasound patterns, such as thyroid nodule hypoechogenicity, spot microcalcifications, and an absent halo sign, can be used to predict the risk of thyroid malignancy 3
- The presence of nodules and their characteristics, such as size, number, and echogenicity, should be evaluated 3
- Ultrasound elastosonography can be used to assess the hardness of nodules as an indicator of malignancy risk 3
- The Thyroid Imaging Reporting and Data System (TI-RADS) can be used to standardize ultrasound features and establish the risk of malignancy 3
Ultrasound Features and Goiter
Ultrasound features are important in determining the strength of the indication for carrying out fine needle aspiration in patients with goiter 3
- Thyroid ultrasound has become an extension of physical examination and should be performed in all patients with goiter 4
- Ultrasound can determine which nodules should be biopsied 4
Diagnostic Role of Ultrasound
Ultrasound plays a crucial role in the diagnosis and management of goiter, including: