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ULTRASOUND
NeckDemonstration data

Thyroid Ultrasound

Thyroid ultrasound is the primary modality for evaluating the thyroid gland and characterizing nodules using high-resolution grayscale and Doppler imaging. It stratifies malignancy risk and guides selection of nodules for fine-needle aspiration through the ACR TI-RADS system. It also assesses the cervical lymph nodes for metastatic involvement and evaluates diffuse thyroid disease.

Indications

  • Palpable thyroid nodule or gland enlargement (goiter)
  • Incidental thyroid nodule detected on CT, MRI, PET, or carotid ultrasound
  • Evaluation of a neck mass or cervical lymphadenopathy
  • Assessment of diffuse thyroid disease in hyper- or hypothyroidism
  • Guidance for fine-needle aspiration biopsy
  • Surveillance of known nodules and post-thyroidectomy neck for recurrence
  • Screening in patients at risk, such as prior neck radiation or familial thyroid cancer

Contraindications & Cautions

  • No contraindications; safe, radiation-free, and repeatable
  • Not a functional study; correlate with thyroid function tests and, for hyperfunctioning nodules, scintigraphy
  • Large substernal goiters extend beyond the sonographic window and may require CT or MRI
  • Follow ALARA for Doppler settings

Patient Preparation

  • No fasting or special preparation required
  • Supine positioning with the neck hyperextended over a pillow or bolster
  • No consent needed for diagnostic scanning; consent obtained separately for FNA
  • Remove neck jewelry and high collars
  • Document relevant history including thyroid function status and prior surgery or radiation

Technique & Parameters

  • High-frequency linear transducer (7-15 MHz)
  • Both lobes and isthmus scanned in transverse and longitudinal planes
  • Gland dimensions and lobe measurements recorded; isthmus thickness noted
  • Each significant nodule measured in three dimensions and assessed for composition, echogenicity, shape, margins, and echogenic foci
  • Color and spectral Doppler to assess nodule and gland vascularity
  • Systematic survey of cervical lymph node levels II-VI
  • Apply ACR TI-RADS to assign points and determine FNA thresholds
  • Cine clips and representative static images documented

Systematic Review

  • Gland size, symmetry, and overall echotexture
  • Nodule composition: cystic, spongiform, mixed, or solid
  • Nodule echogenicity: anechoic, hyperechoic, isoechoic, hypoechoic, or very hypoechoic
  • Shape: wider-than-tall versus taller-than-wide
  • Margins: smooth, ill-defined, lobulated, irregular, or extrathyroidal extension
  • Echogenic foci: comet-tail artifact, macrocalcification, rim calcification, punctate echogenic foci
  • Vascularity on Doppler
  • Cervical lymph nodes for size, shape, hilum, calcification, and cystic change

Key Findings & Significance

  • Solid hypoechoic nodule, taller-than-wide, with irregular margins and punctate echogenic foci is highly suspicious (TR5)
  • Spongiform or purely cystic nodule is benign (TR1-TR2)
  • Macrocalcifications and rim calcification are intermediate features
  • Diffusely heterogeneous hypoechoic gland with hypervascularity suggests Graves disease
  • Heterogeneous gland with pseudonodules and increased vascularity suggests Hashimoto thyroiditis
  • Round lymph node with loss of fatty hilum, microcalcifications, or cystic change suggests metastasis
  • Extrathyroidal extension and abnormal nodes indicate advanced disease

Differential Considerations

  • Solitary solid nodule: benign follicular nodule, adenoma, papillary or follicular carcinoma
  • Multiple nodules: multinodular goiter, still requiring individual TI-RADS assessment of the dominant or suspicious nodules
  • Cystic nodule: colloid cyst, hemorrhagic degeneration, cystic papillary carcinoma
  • Diffuse gland change: Graves disease, Hashimoto thyroiditis, subacute (de Quervain) thyroiditis
  • Hyperechoic solid nodule: benign hyperplastic nodule, follicular adenoma
  • Abnormal node: reactive versus metastatic papillary or medullary carcinoma versus lymphoma

Pearls & Pitfalls

  • TI-RADS determines whether and at what size to biopsy; not every nodule requires FNA
  • Punctate echogenic foci (microcalcifications) are the most specific feature for papillary carcinoma but comet-tail artifact in cystic components is benign
  • Taller-than-wide shape is assessed on the transverse image and is a suspicious feature
  • Do not overlook posterior nodules and the retrosternal extension of a goiter
  • Coexisting Hashimoto thyroiditis increases lymphoma risk and complicates nodule assessment
  • Cystic lymph nodes in the lateral neck are metastatic papillary carcinoma until proven otherwise
  • Correlate a hyperfunctioning nodule with scintigraphy before biopsy, as autonomous nodules are rarely malignant

Structured Report

  • Report gland size and echotexture and any diffuse disease
  • Describe each significant nodule with three measurements, location, and TI-RADS descriptors and score
  • State FNA recommendation based on TI-RADS points and nodule size
  • Report cervical lymph nodes and any suspicious features
  • Compare with prior studies for interval change
  • Impression: enumerate nodules with TI-RADS categories and clear management recommendation (FNA, follow-up interval, or no further imaging)

References

  • Tessler FN et al. ACR Thyroid Imaging Reporting and Data System (TI-RADS), 2017
  • American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer
  • ACR-AIUM-SRU Practice Parameter for the Performance of Thyroid and Parathyroid Ultrasound
  • Bethesda System for Reporting Thyroid Cytopathology

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.