Recommended Approach for Thyroid and Anterior Neck Ultrasound Evaluation
Ultrasound (US) should be the first-line imaging modality for evaluating the thyroid and anterior neck due to its high sensitivity, non-invasiveness, cost-effectiveness, and absence of radiation exposure. 1, 2
Patient Positioning and Equipment
- Position patient supine with neck hyperextended
- Use high-frequency linear transducer (7-15 MHz)
- Apply adequate gel to ensure optimal acoustic coupling
Systematic Scanning Protocol
1. Thyroid Evaluation
Thyroid Size and Morphology
- Measure each lobe in three dimensions (length, width, depth)
- Assess thyroid parenchyma for homogeneity and echogenicity
- Evaluate isthmus thickness and presence of pyramidal lobe
Nodule Characterization (if present)
Document suspicious features that increase risk of malignancy:
Measure nodules in three dimensions
Apply risk stratification systems (e.g., ACR TI-RADS) to guide management 2
Document nodule location for potential FNA guidance
2. Cervical Lymph Node Assessment
Central Compartment (Level VI)
- Scan from hyoid bone to sternal notch
- Evaluate prelaryngeal, pretracheal, and paratracheal nodes
Lateral Neck Compartments (Levels II-V)
- Systematically scan from submandibular region to supraclavicular fossa
- Assess for suspicious lymph node features:
- Round shape (loss of normal oval/elongated shape)
- Absence of fatty hilum
- Microcalcifications
- Cystic changes
- Peripheral vascularity
- Solid thyroid-like appearance 1
3. Adjacent Structures
- Evaluate relationship of thyroid to:
- Trachea (for deviation or compression)
- Esophagus
- Carotid arteries and jugular veins
- Sternocleidomastoid muscles
- Strap muscles
Documentation Requirements
- Comprehensive description of thyroid parenchyma
- Detailed characterization of any nodules using standardized terminology
- Measurements of thyroid lobes and any nodules
- Assessment of cervical lymph nodes
- Color Doppler evaluation of nodule and thyroid vascularity
- Clear indication of findings that warrant further investigation
Clinical Integration and Follow-up
For nodules meeting criteria for biopsy based on ultrasound characteristics and size:
- Highly suspicious nodules ≥1 cm
- Moderately suspicious nodules ≥1-1.5 cm
- Mildly suspicious nodules ≥1.5-2 cm
- Very low suspicion nodules ≥2 cm 2
US can guide fine-needle aspiration (FNA) for suspicious nodules 1
For post-treatment thyroid cancer patients, US is the first imaging investigation for suspected recurrence 1
Pitfalls to Avoid
- Incomplete examination (failure to assess all compartments)
- Inadequate documentation of nodule characteristics
- Misinterpretation of normal anatomic variants as pathology 3
- Over-reliance on a single suspicious feature (multiple suspicious features increase specificity) 1
- Failure to correlate with clinical findings and laboratory data
Limitations of Thyroid US
- Operator dependency affecting reproducibility 4
- Limited visualization of deep structures (retrotracheal, retrosternal extension)
- Cannot definitively distinguish benign from malignant disease in all cases 5
- May require complementary cross-sectional imaging (CT/MRI) for complete assessment of extensive disease 1
By following this systematic approach to thyroid and anterior neck ultrasound evaluation, clinicians can maximize diagnostic accuracy and appropriately guide management decisions for patients with thyroid disease.