Quick answer: a thyroid ultrasound uses sound waves, not radiation, to take pictures of the butterfly-shaped thyroid gland at the front of your neck. It needs no preparation, is painless and usually takes 15 to 30 minutes. You lie on your back with a pillow under your shoulders so your neck is gently extended. It is mainly used to look at thyroid nodules, which are extremely common: ultrasound finds them in up to about 68% to 70% of adults in some age groups, and the vast majority are benign. If a nodule is found, the radiologist may give it a TI-RADS score, which helps decide whether it needs a biopsy, follow-up or nothing.
Many people are sent for a thyroid ultrasound after a doctor feels a lump or after a nodule is spotted by chance on another scan. It is a simple test, and the hardest part is often waiting for the results.
What a thyroid ultrasound shows
Ultrasound shows the size and structure of the thyroid and nearby structures in the neck. It is used to:
- check whether a lump in the neck comes from the thyroid or from something nearby
- look at the features of thyroid nodules, to tell whether they look benign or need a biopsy
- look for additional nodules when one has been felt
- check whether a nodule has grown over time
- guide a needle biopsy (fine-needle aspiration)
Ultrasound cannot tell whether your thyroid is overactive or underactive. That is checked with blood tests and, sometimes, a radioactive iodine uptake test. See [link: Thyroid Scan and Uptake Test Explained].
How common are thyroid nodules?
Very common. About 5% to 10% of adults have a nodule large enough for a doctor to feel. Ultrasound is much more sensitive and finds nodules in up to about 68% to 70% of adults in some age groups. The vast majority are benign areas of thyroid tissue that pose no health risk.
How to prepare
- No fasting or special preparation is needed.
- Wear a top that leaves your neck free, such as a low or open neckline.
- Remove necklaces and earrings before the exam.
- Bring previous thyroid ultrasounds if they were done elsewhere, so the radiologist can compare nodule size.
What happens during the scan
- You lie on your back on an exam table, usually with a pillow or roll under your shoulders so your head tilts back and your neck is extended.
- The sonographer applies warm gel to your neck.
- They move the transducer (probe) over each side of your neck with light pressure.
- You may be asked to swallow or turn your head slightly.
- A Doppler study may be used to look at blood flow in the gland or a nodule.
The exam usually takes 15 to 30 minutes. Afterward the gel is wiped off and you can go back to your normal activities.
From the scanner room: [TU EXPERIENCIA: si has trabajado con pacientes de tiroides, cómo se relaciona en la práctica la ecografía con la gammagrafía y qué suelen preguntar los pacientes.]
Does it hurt?
No. You feel the gel and gentle pressure. Some people find the extended neck position uncomfortable, especially with neck or back problems; tell the sonographer, who can adjust the pillow.
Understanding TI-RADS
Many U.S. radiologists use the American College of Radiology’s TI-RADS system. Each nodule gets points for features such as its composition, brightness, shape, edges and any bright spots, and the total places it in one of five levels. The level and the nodule’s size decide the recommendation:
| TI-RADS level | Meaning | Biopsy (FNA) recommended if | Follow-up ultrasound if |
|---|---|---|---|
| TR1 | Benign | Not recommended | Not needed |
| TR2 | Not suspicious | Not recommended | Not needed |
| TR3 | Mildly suspicious | 2.5 cm or larger | 1.5 cm or larger |
| TR4 | Moderately suspicious | 1.5 cm or larger | 1.0 cm or larger |
| TR5 | Highly suspicious | 1.0 cm or larger | 0.5 cm or larger |
A TI-RADS level is not a diagnosis. Even suspicious-looking nodules are often benign, and only a biopsy can confirm cancer. Your doctor will also consider your risk factors, such as previous neck radiation or a family history of thyroid cancer.
If you need a biopsy
A fine-needle aspiration (FNA) uses a thin needle, guided by ultrasound, to take cells from the nodule. It is usually done in the imaging department with local anesthetic and takes a short time. See [link: Ultrasound-Guided Biopsy: What to Expect].
Results
A radiologist reviews the images and sends a signed report to your doctor, who will share the results. In some cases the radiologist discusses the results with you after the exam.
Tips from the technologist
[TU EXPERIENCIA: 2-3 consejos propios. Ideas: llevar ecografías previas en CD o portal, pedir que te digan el tamaño de los nódulos para comparar, avisar de problemas cervicales.]
Frequently asked questions
Do I need to fast for a thyroid ultrasound?
No. No preparation is needed.
How long does a thyroid ultrasound take?
Usually 15 to 30 minutes.
Can a thyroid ultrasound detect cancer?
It can show features that raise or lower suspicion, but only a biopsy can confirm cancer.
Can ultrasound show if my thyroid is overactive or underactive?
No. That requires blood tests and sometimes a radioactive iodine uptake test.
Is a thyroid ultrasound safe?
Yes. It uses sound waves, has no known harmful effects and involves no radiation.
This article is for general information and does not replace advice from your doctor.