Thyroid ultrasound

What it is

Thyroid ultrasound uses sound waves to look at the thyroid gland at the front of the neck. It shows its size, the structure of the tissue, the presence and characteristics of nodules and, when needed, the lymph nodes of the neck.

It uses no radiation, needs no preparation and usually takes 10–20 minutes.

When it is recommended

• a palpable nodule or swelling in the neck
• enlargement of the thyroid (goiter)
• a nodule discovered incidentally on another exam (CT, MRI, carotid Doppler)
• follow-up of a known nodule
• in some thyroid diseases (e.g. Hashimoto's thyroiditis or Graves' disease), at the endocrinologist's discretion

Ultrasound is not automatically needed for every abnormal TSH or for every person without symptoms.

Structure and function are two different things

• Ultrasound shows how the gland looks.
• Blood tests — mainly TSH and FT4 — show how it functions.

A thyroid that looks normal may produce too little or too much hormone, while a nodule may exist with completely normal hormones. That is why ultrasound and blood tests complement each other.

Thyroid nodules

Nodules are very common — they appear in almost half of adults over 60 — and the vast majority are benign.

The doctor assesses the size, composition (cystic, solid or mixed), echogenicity, margins, shape and the presence of calcifications. Systems such as TI-RADS group nodules by risk and help decide whether follow-up alone or a biopsy is needed.

Fine-needle aspiration biopsy

Not every nodule needs a biopsy. When it is indicated, a small sample of cells is taken with a fine needle, under ultrasound guidance. The procedure is quick and usually well tolerated. An indeterminate result may require repetition or additional tests.

Limitations

Ultrasound cannot by itself confirm or rule out thyroid cancer. The growth of a nodule does not necessarily mean cancer, and the absence of growth does not replace the recommended follow-up. The interval between check-ups is set according to the risk category.

When an assessment is needed

Ask for a consultation for a new mass in the neck, persistent hoarseness or difficulty swallowing. Bring previous reports, thyroid tests and any information about previous radiation to the neck or a family history of thyroid cancer.