Can a neck ultrasound visualize the thyroid gland?

Thyroid Visualization on Neck Ultrasound

Yes, the thyroid gland is routinely and effectively visualized on neck ultrasound—in fact, ultrasound is the premier imaging modality for evaluating the thyroid gland. 1, 2, 3, 4

Why Ultrasound Excels for Thyroid Imaging

Ultrasound is the first-line and most effective imaging technique for thyroid evaluation, providing superior morphological detail compared to other modalities. 2, 3 The American College of Radiology specifically recommends ultrasound as the preferred initial imaging for suspected thyroid masses. 5

Key Advantages of Thyroid Ultrasound

• Superior sensitivity: Ultrasound is significantly more sensitive than CT for detecting thyroid nodules and characterizing their features. 1
• Comprehensive visualization: It visualizes the entire thyroid gland, including both lobes and the isthmus, and can detect non-palpable nodules. 3, 6, 7
• Detailed characterization: Ultrasound accurately assesses nodule composition, echogenicity, margins, calcifications, and shape—all critical for malignancy risk stratification using ACR TI-RADS criteria. 1, 8
• No radiation exposure: Unlike CT or nuclear medicine scans, ultrasound involves no ionizing radiation. 3
• Real-time guidance: It enables accurate needle placement for fine-needle aspiration biopsy of suspicious nodules. 3, 6
• Cost-effective and widely available: Ultrasound is relatively inexpensive, rapid, and accessible in most clinical settings. 3, 6

What Ultrasound Shows in the Thyroid

Neck ultrasound provides detailed information about:

• Thyroid size and volume estimation 3
• Tissue density (echogenicity) 3
• Vascular flow patterns using color-flow Doppler 3, 7
• Presence and characteristics of thyroid nodules (solid vs. cystic, benign vs. suspicious features) 1, 3
• Regional lymphadenopathy in the neck that may indicate thyroid cancer metastasis 5, 3
• Thyroid bed abnormalities after thyroidectomy 5

Important Limitations to Recognize

While ultrasound is excellent for thyroid visualization, it has specific limitations:

• Substernal extension: Ultrasound cannot adequately evaluate the inferior border of thyroid tissue that extends behind the sternum into the mediastinum. 1, 8 CT with contrast is superior for assessing substernal goiters and tracheal compression. 8
• Deep structures: Areas acoustically shadowed by bone or air are better evaluated with cross-sectional imaging (CT or MRI). 5
• Operator dependency: Image quality and interpretation depend significantly on the skill and experience of the sonographer. 5
• Functional information: Ultrasound cannot determine thyroid function—this requires laboratory testing (TSH) and potentially radioiodine uptake scanning in hyperthyroid patients. 2

Clinical Algorithm for Thyroid Imaging

Start with TSH measurement before any imaging, as this guides the appropriate imaging pathway. 2

• If TSH is normal (euthyroid): Proceed directly to thyroid ultrasound for morphological evaluation. 2
• If TSH is low (hyperthyroid): Perform ultrasound first, then add radioiodine uptake scan to determine the cause of thyrotoxicosis. 2
• If TSH is high (hypothyroid): Imaging is generally not indicated, but ultrasound is appropriate if a structural abnormality is suspected. 2

Add CT with contrast when:

• There are obstructive symptoms (dyspnea, dysphagia, stridor) suggesting tracheal compression 8
• Physical examination or ultrasound suggests substernal extension 8
• There is concern for invasive features or bulky nodal disease in thyroid cancer 1

Common Pitfalls to Avoid

• Do not order radioiodine uptake scans in euthyroid patients—scintigraphy has no role in determining malignancy risk when TSH is normal. 2, 8
• Do not rely solely on ultrasound for large goiters with suspected substernal extension—you will miss the inferior extent and degree of airway compromise. 1, 8
• Do not assume ultrasound can distinguish benign from malignant nodules with certainty—it provides risk stratification, but tissue diagnosis requires fine-needle aspiration. 3