Guidelines for Thyroid Nodule Ultrasound Evaluation

Equipment and Technical Requirements

Use a medium‑ or high‑grade high‑resolution ultrasound system equipped with a wide‑band linear array probe capable of 7–18 MHz frequencies for optimal thyroid imaging. 1, 2, 4
Adjust the probe frequency flexibly according to nodule depth and the degree of thyroid enlargement to maintain image resolution. 1, 2
For markedly enlarged or retro‑sternal goiters, a lower‑frequency convex array probe may be employed to achieve adequate penetration. 1, 4

Position the patient supine with a pillow behind the neck to hyper‑extend the cervical region, exposing the anterior thyroid surface. 2, 3, 4
Turn the head to the opposite side when scanning each lobe to improve access and visualization. 2, 3
Perform transverse and longitudinal scans of both thyroid lobes, the isthmus, and the pyramidal lobe without omission. 2, 3, 4
In post‑thyroidectomy patients, scan the thyroid bed in both planes to assess residual tissue. 2, 3
Include cervical lymph‑node evaluation, focusing on levels VI, III, and IV per AJCC classification; assess levels I, II, V, and VII when clinically indicated. 2, 3, 4
Level VII nodes are difficult to visualize with ultrasound; cross‑sectional imaging (CT or MRI) is preferred for this region. 2, 3, 4

Gray‑scale B‑mode with a high‑frequency linear probe is the essential primary modality for thyroid nodule evaluation and forms the foundation of all risk‑stratification systems. 1, 2, 3, 4
Optimize image quality by adjusting probe frequency, focal zone, gain, time‑gain compensation, and imaging depth/width. 1, 2
Position the probe as close as possible to the thyroid tissue to enable use of the highest feasible frequency for superior resolution. 1, 2, 3

Color/Power Doppler is a recommended adjunct to gray‑scale imaging for assessing vascularity within thyroid lesions. 1, 2, 3, 4
Set the Doppler velocity scale to 1–5 cm/s, adjust gain and wall‑filter as needed, and standardize settings for maximal sensitivity without excessive noise. 1, 2, 3
Maintain full probe‑skin contact with minimal pressure to avoid compressing small vessels and distorting flow signals. 1, 2, 3
The utility of Doppler for distinguishing benign from malignant nodules remains controversial, with conflicting study results. 5, 6, 7, 8

Elastography may be employed selectively but should not be incorporated into primary risk‑stratification algorithms because of limited reproducibility and strong dependence on equipment and operator technique. 5, 6, 8, 9
When performed, use light, perpendicular probe contact, ask the patient to hold breath briefly if neck motion is significant, and set the region of interest to include the target nodule and surrounding thyroid tissue. 2, 3, 4, 9
Strain elastography requires system‑specific pressure and compression frequency adjustments; shear‑wave elastography demands selection of stable, artifact‑free images without probe‑induced pressure. 2, 3, 4, 9
Quantitative values obtained from different elastography platforms are not interchangeable and cannot be directly compared. 5, 6, 7, 8

CEUS provides significant diagnostic value for collapsing benign cystic or predominantly cystic thyroid nodules but is not recommended for routine evaluation. 5, 6, 7, 8
Apply minimal probe pressure while ensuring full contact to obtain optimal perfusion signals. 2, 9
Absence of enhancement or only scant punctate‑linear enhancement in cystic nodules yields high specificity but relatively low sensitivity for confirming benign status. 5, 6, 7, 8

Image‑quality control is critical for reliable nodule detection and accurate risk stratification; this is a Grade B recommendation. 2, 3, 9
Tailor scanning techniques and imaging parameters to the specific ultrasound system and patient characteristics to maintain consistent image quality. 1, 2, 4

Apply standardized risk‑stratification frameworks—ACR TI‑RADS, ATA guidelines, or C‑TIRADS—based on gray‑scale ultrasound features to guide management decisions. 10, 11
ACR TI‑RADS assigns points for composition, echogenicity, shape, margin, and echogenic foci, categorizing nodules from TR1 (benign) to TR5 (highly suspicious). 11
The diagnostic performance of ACR TI‑RADS and ATA guidelines is comparable, each demonstrating high accuracy for malignancy prediction. 10
These systems are designed for ease of implementation across diverse ultrasound practices. 11

Do not rely on advanced techniques such as elastography or CEUS as primary decision‑making tools for risk stratification. 5, 6, 8, 9
Ensure that ultrasound radiologists possess a precise understanding of all sonographic terminology; this is a Grade A recommendation. 5, 7, 8
Recognize inherent observer variability in interpreting ultrasound features; continuous specialized training—especially for less‑experienced radiologists—is essential. 9
Avoid excessive probe pressure during Doppler examinations, as it compresses small vessels and impairs accurate blood‑flow visualization. 1, 2, 3