From the Guidelines
Ultrasound is the preferred initial radiological method for evaluating thyroid lesions. This non-invasive technique provides excellent visualization of thyroid anatomy and potential abnormalities without exposing patients to ionizing radiation, as recommended by the American College of Radiology 1. Ultrasound can effectively characterize nodules as solid, cystic, or mixed, and can detect features that may suggest malignancy such as microcalcifications, irregular margins, hypoechogenicity, and increased vascularity.
Key Benefits of Ultrasound
- Wide availability
- Relatively low cost
- Lack of radiation exposure
- Superior ability to characterize thyroid nodule features that help determine the risk of malignancy and guide management decisions
The real-time nature of ultrasound also allows for immediate assessment and guidance for fine needle aspiration biopsy if needed, as supported by the National Comprehensive Cancer Network guidelines 1. While CT scans and MRI can provide information about the thyroid, they are generally reserved for specific situations such as evaluating the extent of known thyroid cancer, assessing retrosternal extension of goiters, or examining relationships with adjacent structures.
Specific Situations for Alternative Imaging Modalities
- CT neck without IV contrast is usually appropriate if there is suspicion for substernal extension 1
- MRI neck without and with IV contrast are second-line studies that are usually appropriate and alternatives depending on clinical findings 1
Fine-needle aspiration (FNA) with ultrasound guidance is the preferred procedure for evaluating suspicious thyroid nodules, and cytologic examination of an FNA specimen can be categorized using the 2017 Bethesda System for Reporting Thyroid Cytopathology 1. Molecular diagnostic testing may also be useful in evaluating FNA samples that are indeterminate to assist in management decisions. Overall, ultrasound is the preferred initial radiological method for evaluating thyroid lesions due to its effectiveness, safety, and ability to guide management decisions.
From the Research
Preferred Radiological Method for Evaluating Thyroid Lesions
The preferred initial radiological method for evaluating thyroid lesions is a topic of discussion among medical professionals.
- Ultrasound is the most commonly used imaging modality for characterizing thyroid nodules, as it provides high-resolution images and can help identify features that increase the likelihood of malignancy, such as microcalcifications, solid composition, and central vascularity 2.
- Computed Tomography (CT) scans and Magnetic Resonance Imaging (MRI) are also used to evaluate thyroid lesions, but they are not as sensitive as ultrasound in detecting impalpable nodules and are typically used to size known lesions and detect cervical lymphadenopathy in thyroid cancer cases 3.
- Ultrasound elastography has also been shown to be valuable in discriminating between benign and malignant thyroid nodules, with a sensitivity and specificity ranging from 73 to 98% and 71 to 100%, respectively 4.
- The predictive value of sonographic features, such as microcalcifications, blurred nodular margins, and solid and hypoechoic appearance, can also be used to preoperatively evaluate malignant thyroid nodules in a multinodular goiter 5.
Comparison of Radiological Methods
A comparison of radiological methods for evaluating thyroid lesions reveals that:
- Ultrasound is more sensitive than CT and MRI in detecting thyroid nodules, but it may not be as effective in evaluating lesions larger than 1.5 cm 6.
- MRI-guided biopsies of thyroid lesions are technically feasible and safe, but may not be as effective as ultrasound-guided biopsies for lesions smaller than 1.5 cm 6.
- The choice of radiological method depends on the specific clinical scenario and the characteristics of the thyroid lesion, with ultrasound being the preferred initial method for evaluating most thyroid lesions 2.