Thyroid Gland Ultrasound
Introduction · Anatomical Reference · Reporting
THYROID GLAND ULTRASOUND
Lesson: Thyroid Gland – Anatomical and Sonographic Assessment
Introduction
Thyroid ultrasonography is a non-invasive, radiation-free, high-resolution imaging method for evaluating thyroid size, parenchymal echotexture, focal nodules, vascularity, and adjacent cervical lymph nodes. It is a first-line imaging test for suspected thyroid nodules or goiter.
A high-frequency linear transducer (typically 7–15 MHz or higher as appropriate) provides detailed grayscale and color Doppler assessment of the superficial thyroid gland. Ultrasound morphology guides risk stratification but does not independently establish thyroid function or a definitive histological diagnosis.
Anatomical Structures Evaluated
- Right thyroid lobe: Length, width, anteroposterior depth, contour and volume.
- Left thyroid lobe: Length, width, depth, contour and volume.
- Isthmus: Thickness and focal lesions.
- Parenchyma: Echogenicity, homogeneity and diffuse inflammatory changes.
- Thyroid nodules: Location, three-dimensional size, composition, echogenicity, shape, margins and echogenic foci.
- Vascularity: Global and focal color Doppler patterns.
- Cervical lymph nodes: Size, shape, hilum, cystic change, calcifications and vascularity.
- Adjacent structures: Trachea, strap muscles, carotid vessels and accessible extrathyroidal tissues.
Objectives of the Examination
- Assess gland dimensions, volume, symmetry and enlargement.
- Characterize diffuse parenchymal disease and suspected thyroiditis.
- Detect and characterize focal nodules and document interval growth.
- Apply ACR TI-RADS when appropriate for thyroid nodule risk stratification.
- Evaluate suspicious cervical lymphadenopathy and possible extrathyroidal extension.
- Guide image-directed sampling when clinically indicated.
Ultrasound Examination Technique
- Position: Supine with gentle neck extension, as tolerated.
- Transducer: High-frequency linear probe, adjusted to patient habitus and lesion depth.
- Planes: Transverse and longitudinal images of both lobes and the isthmus.
- Measurements: Record each lobe in three orthogonal dimensions; estimated lobe volume = length × width × depth × 0.52 (all in cm, result in mL). Measure isthmus AP thickness.
- Nodules: Record location, size in three dimensions, composition, echogenicity, shape, margins and echogenic foci. Document representative images.
- Doppler: Evaluate vascularity as indicated; Doppler is not an ACR TI-RADS scoring feature.
- Neck survey: Assess relevant cervical lymph-node compartments when indicated.
Clinical Applications
- Palpable thyroid nodule, neck swelling or goiter.
- Incidental thyroid nodule requiring sonographic characterization.
- Suspected thyroiditis or diffuse gland disease.
- Surveillance of previously characterized nodules.
- Assessment of suspicious cervical lymph nodes.
- Pre-procedure localization and ultrasound-guided biopsy.
Interpretation and Reporting
Report lobe and isthmus dimensions, background parenchymal appearance, clinically relevant nodules, suspicious lymph nodes and a clear impression. ACR TI-RADS scores are derived from composition, echogenicity, shape, margins and echogenic foci; size-based biopsy and follow-up recommendations depend on the final category.
Ultrasound cannot determine thyroid hormone status. Correlate with thyroid function tests and clinical findings. Retro-sternal extension may be incompletely visualized, and cross-sectional imaging may be necessary for selected cases.
Conclusion
High-resolution thyroid ultrasound provides reliable structural assessment of the thyroid gland and helps guide evidence-based management of nodules and cervical abnormalities.
| Patient Name | Age / Sex | ||
|---|---|---|---|
| Referring Doctor | Date |
Indication: Thyroid/neck ultrasound. Clinical indication: _____.
Technique: High-frequency grayscale and color Doppler ultrasound of the thyroid gland in transverse and longitudinal planes. Cervical lymph nodes surveyed as clinically indicated.
Right Thyroid Lobe: Measures ___ × ___ × ___ cm (L × W × AP), estimated volume ___ mL. Normal contour and homogeneous echotexture. No discrete focal lesion.
Left Thyroid Lobe: Measures ___ × ___ × ___ cm (L × W × AP), estimated volume ___ mL. Normal contour and homogeneous echotexture. No discrete focal lesion.
Isthmus: AP thickness ___ mm. Normal echotexture; no focal nodule.
Total Thyroid Volume: Approximately ___ mL (sum of lobe volumes).
Parenchyma: Homogeneous echotexture and preserved echogenicity without diffuse inflammatory change.
Color Doppler: No abnormal diffuse hypervascularity.
Thyroid Nodules: No discrete thyroid nodule identified. If present, replace this sentence and document for each relevant nodule: side/location, ___ × ___ × ___ mm, composition, echogenicity, shape, margins, echogenic foci, total ACR TI-RADS points and TR category.
Cervical Lymph Nodes: No suspicious cervical lymphadenopathy in the surveyed regions.
Additional Findings: No additional abnormality identified in the examined regions.
Unremarkable sonographic appearance of the thyroid gland. No discrete thyroid nodule or suspicious cervical lymphadenopathy in the surveyed regions.
Correlate with clinical examination and thyroid function tests where indicated. For identified nodules, determine surveillance or fine-needle aspiration eligibility using ACR TI-RADS category, nodule size and clinical risk factors.
Ultrasound evaluates thyroid morphology but not thyroid function or histology. Retrosternal extension may be incompletely visualized. Cervical lymph node findings apply only to surveyed regions. This normal-report template must be verified and edited to match the actual examination before signing.
Please report typographical errors for correction. Interpretation requires clinical correlation.
MBBS MD (Consultant Radiologist)
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