Diagnosis: non-laboratory tests

A thyroid ultrasound is usually done in case of goitre (swollen thyroid), or to check for thyroid nodules. It can help determine the number and size of thyroid nodules, and whether they are solid or filled with fluid. Ultrasound can also be used to check whether any nearby lymph nodes are enlarged and to guide a fine needle aspiration biopsy (FNA).

• Ultrasound - Thyroid (Radiological Society of North America)

• Thyroid ultrasound (Medline Plus)

• Ultrasound (Cancer Research UK)

Fine needle aspiration is performed to diagnose thyroid disease or thyroid cancer. Examination of thyroid tissue obtained by means of FNA helps determine whether thyroid nodules are benign (non-cancerous) or malignant (cancerous).

• Fine Needle Aspiration Biopsy of Thyroid Nodules (printable pdf) (American Thyroid Association)

• Ultrasound-Guided Fine Needle Aspiration Biopsy of the Thyroid (Radiological Society of North America)

• Fine needle aspiration of the thyroid (Medline Plus)

Alternative names: nuclear thyroid scan, thyroid scintigraphy, thyroid pertechnetate scan

The thyroid scan is similar to the radioactive iodine uptake test (see next box). It is a type of nuclear medicine imaging that is used to determine the size, shape and position of the thyroid gland.

A thyroid scan is usually done to evaluate a goitre or thyroid nodules; sometimes to diagnose hypothyroidism (incl Hashimoto’s and post-partum thyroiditis) and hyperthyroidism; and it can also help identify areas of the gland that may have cancer.

• Thyroid scan (Medline Plus)

• Thyroid scan (HealthLink BC)

A radioactive iodine uptake test is performed to determine a patient’s thyroid function, particularly for the diagnosis of hyperthyroidism. It measures how much radioactive iodine is taken up by the thyroid gland in a certain time period. Unlike the thyroid scan (see the previous box), RAIU does not involve imaging.

• Radioactive iodine uptake (Medline Plus)

Combined information about thyroid scan and RAIU

• Thyroid scan and uptake (Radiological Society of North America)

• Thyroid Scans and Uptake Tests (Patient.info)

A Computed Tomography scan uses multiple x-ray pictures to create a detailed, three-dimensional image of the inside of the body. This procedure can provide a cross-sectional view of the neck (and other organs), which is particularly useful for examining those areas that cannot be seen by means of ultrasound.

A CT scan can be used to diagnose thyroid cancer; determine the location and size of tumours; and to investigate whether the cancer has spread to other, nearby tissues and lymph nodes, as well as more distant parts of the body, such as the chest and abdomen.

• CT scan for thyroid cancer (Cancer Research UK)

• CT Scan for Cancer (American Cancer Society)

A positron emission tomography (PET) scan is a sensitive, nuclear imaging technique that uses glucose tracers that release low levels of radiation. As cancer cells grow more quickly and, therefore, take up more of the sugar than normal cells, they will show up brighter on the scan. This helps determining whether cancer has come back after surgery; and whether, and where, the cancer has spread (including to sites outside of the neck).

It is a useful alternative to scans that make use of radioactive iodine for patients whose thyroid cancer does not take up or absorb radioactive iodine.

A PET scan is often combined with a CT scan, because a PET scan alone doesn't provide a very detailed image.

• PET scan (Cancer Research UK)

• PET-CT scan for thyroid cancer (Cancer Research UK)

• Positron Emission Tomography and Computed Tomography (PET-CT) Scans (Cancer.Net, American Society of Clinical Oncology)

Magnetic resonance imaging (MRI) uses radio waves, strong magnets (instead of x-rays) and a computer to produce detailed images of the neck area and other parts of the body. These images can be used to distinguish between normal, healthy tissue and diseased tissue.

While ultrasound is usually the preferred method for examining tumours inside the thyroid, MRI (or a CT scan) is considered more useful for investigating whether thyroid cancer has extended into surrounding tissues, such as the trachea (windpipe) and esopahgus (feeding tube), or spread to more distant parts of the body (staging). MRI is also used to determine the size of a tumour and to plan for the treatment after cancer diagnosis.

• MRI scan for thyroid cancer (Cancer Research UK)

• MRI for Cancer (American Cancer Society)

• Magnetic Resonance Imaging (MRI) (Cancer.Net, American Society of Clinical Oncology)

If a patient has been diagnosed with thyroid cancer (especially follicular thyroid cancer), a plain x-ray of the chest may be done to investigate whether the cancer has spread to the lungs.

• X-rays and Other Radiographic Tests for Cancer (American Cancer Society)

• X-ray (Radiography) - Chest (Radiological Society of North America)

This procedure is mainly performed after a patient has been diagnosed with thyroid cancer and needs surgery. Thyroid tumours sometimes press on the vocal cords. Thyroid surgery may occasionally result in complications, such as damage to the nerves that lead to the vocal cords. This damage may cause temporary or permanent loss of, or change in, voice. Laryngoscopy can be used pre-surgery to check the anatomy and function of the larynx (voice box) and determine whether the vocal cords are moving normally.

• Laryngoscopy for thyroid cancer (Cancer Treatment Centers of America - archived page)

• Laryngoscopy (American Cancer Society)