Thyroid Ultrasound: Under­stand­ing the Exam and Report

What is a thyroid ultrasound?

Ultrasound is a noninvasive way to make images of the thyroid without X-rays or radioactive iodine. A handheld device called a transducer sends sound waves into the neck and receives the returning echoes. A computer turns those echoes into images.

Ultrasound can measure the thyroid gland, show whether it is uniform or irregular, identify nodules, and examine nearby lymph nodes. It can also guide a needle during fine-needle aspiration or another ultrasound-guided procedure.

When might thyroid ultrasound be useful?

Thyroid ultrasound has four practical uses: measuring the gland and nodules, following changes over time, evaluating the neck before or after thyroid cancer treatment, and guiding a needle or treatment device. Current guidance supports these general roles when there is a clinical reason for imaging.

A clinician may consider ultrasound when a neck examination finds a thyroid lump or enlarged gland, another scan shows a possible thyroid nodule, symptoms or history raise a structural concern, a known nodule needs evaluation, or thyroid cancer follow-up requires examination of the thyroid bed and cervical lymph nodes.

What happens during the exam?

How should I prepare?

Thyroid ultrasound usually requires little or no special preparation. Wear loose clothing that leaves your neck accessible and be prepared to remove necklaces. Follow the imaging facility's instructions, especially if another procedure is planned.

During the examination

The patient usually lies on an examination table with the neck gently extended. Gel is placed on the skin, and the transducer is moved across the lower front and sides of the neck. The examiner records images and measurements of the thyroid and any relevant nodules or lymph nodes.

The examination is usually painless and does not use ionizing radiation. It often takes about 30 minutes, although timing varies with the clinical question and the number of findings. Ultrasound does not normally require an injection, radioactive material, or special recovery time.

Bring or make available earlier ultrasound reports and images when possible. A direct comparison can be more useful than comparing written measurements from different examinations alone.

How will I get my results?

Ask who will review your images, when the report should be ready, and how your clinician will explain the findings and next steps. If results have not arrived when expected, contact the ordering office.

What should a thyroid ultrasound report describe?

Image quality and careful interpretation matter. Modern reporting systems add a standardized vocabulary so clinicians can describe findings consistently.

The thyroid gland

The report may describe the size of each lobe and the isthmus, the gland's overall texture, blood flow when relevant, and whether the tissue appears uniform or heterogeneous.

Thyroid nodules

A nodule may be measured in three dimensions and described by its location, composition, echogenicity, shape, margins, and echogenic foci. In plain language, the report is describing whether the nodule is solid or fluid-filled, how bright or dark it appears, whether its borders are smooth, and whether it contains particular reflective areas.

Cervical lymph nodes and nearby structures

When clinically appropriate, the examination may include lymph nodes in the central and lateral neck. The report should note lymph nodes or other findings that require correlation or further evaluation.

Common report terms

• Solid or cystic: Describes whether a nodule contains tissue, fluid, or a mixture of both.
• Hypoechoic: Appears darker than the surrounding thyroid tissue.
• Isoechoic: Has a similar brightness to the surrounding thyroid tissue.
• Heterogeneous: Has an uneven appearance or texture. Check whether the report is describing the whole gland or a particular nodule.
• Margins: The outer edges of a nodule, which may be described as smooth, lobulated, or irregular.
• Echogenic foci: Bright spots on the image. These can include calcium deposits, called calcifications, or other types of echoes.

What does TI-RADS mean?

TI-RADS stands for Thyroid Imaging Reporting and Data System. The American College of Radiology (ACR) system adds points for five ultrasound feature groups: composition, echogenicity, shape, margins, and echogenic foci. The total determines the category, from TR1 to TR5.

The category describes how a nodule looks on ultrasound. It is not a cancer diagnosis or a cancer stage. The next step depends on both the category and the nodule's size.

What does my TI-RADS category mean?

The usual ACR recommendations below apply to nodules that have not already been biopsied and use the largest measured dimension. Sizes are shown in millimeters (mm) and centimeters (cm).

These are ACR thresholds. Other reporting systems may use different cutoffs, so check which system your report uses.

Why might a suspicious nodule not need a biopsy?

A nodule can look suspicious yet be too small for biopsy under ACR criteria. Depending on its size and category, it may need monitoring or no routine imaging. The thyroid biopsy guide explains what happens when a biopsy is recommended.

What if the nodule grows or causes symptoms?

Growth alone does not establish cancer. Your clinician can compare earlier images and reassess the nodule. Treatment may be considered for a confirmed benign nodule that causes pressure or visible swelling. A low TI-RADS category alone does not establish eligibility for ablation. Read about monitoring and treatment of thyroid nodules.

What can ultrasound not tell?

Ultrasound can estimate how suspicious a nodule appears, but it cannot confirm or exclude cancer in every case. Benign and malignant nodules can share features. When the combined findings meet appropriate criteria, an ultrasound-guided fine-needle aspiration may be recommended.

Ultrasound also does not show whether the thyroid is producing too much or too little hormone. Blood tests are used for that question. A nuclear medicine uptake test may be useful in selected situations, such as investigating the cause of hyperthyroidism.

A report should be considered together with symptoms, examination findings, thyroid blood tests, risk factors, earlier images, and any previous biopsy result.

How is ultrasound used during follow-up?

Follow-up may be recommended for a nodule that does not meet biopsy criteria, a nodule with a benign biopsy result, selected thyroid cancers under active surveillance, or the neck after thyroid cancer treatment. The schedule depends on the ultrasound pattern, size, clinical history, previous results, and the management system being used.

Small differences in measurement can occur because of patient position, imaging technique, equipment, and where the measurement is placed. A clinician looks at the overall pattern, meaningful interval change, and any new suspicious features rather than relying on one number alone.

If a report recommends follow-up, ask what finding is being monitored, when the next examination is due, and what change would alter the plan.

Questions to ask your clinician

• Why was this ultrasound ordered?
• Does the report describe the thyroid gland, nodules, and relevant lymph nodes?
• Which reporting system was used?
• What does the risk category mean in my situation?
• Does any nodule need biopsy, follow-up, or no further action?
• Were earlier images available for direct comparison?
• What change would alter the follow-up plan?