The thyroid gland is a butterfly-shaped organ consisting of two lobes, with one on each side of the neck connected by a narrow band. It is wrapped around the front of the throat between the Adam’s apple and the collar bones. The thyroid gland creates essential hormones that help regulate metabolic processes including body temperature, digestion, cardiac function, etc.
Ultrasound examination of the thyroid is a safe and painless procedure that uses sound waves to create high-resolution images of the thyroid gland and the adjacent structures in the neck. The examination usually takes about 30 minutes to perform.
Ultrasound examination (also known as sonography) is a non-invasive modality that uses high-frequency sound waves to create real-time images. The sound waves are generated by a small transducer and transmitted into the body. Sound waves that are reflected back to the transducer are converted to the images visible on the screen of the ultrasound machine. Because ultrasound images are captured in real-time, they can reveal normal / abnormal structures, show movement of internal organs, and even evaluate blood flowing through the arteries and veins. Because ultrasound examinations do not use ionizing radiation, there is no radiation exposure to the patient (unlike X-rays and CAT scans). For standard diagnostic ultrasound examinations, there are no known harmful effects on humans.
Common indications for a thyroid ultrasound evaluation include:
- Thyroid Nodule
- Enlarged thyroid gland (thyroid goiter)
- Neck mass adjacent to the thyroid gland
- Difficulty swallowing or breathing
- Acute or chronic thyroiditis
- Needle biopsy
It is not unusual for one or more lumps or nodules to develop in the thyroid tissue. The incidence of these nodules increases with age. Approximately 5-10% of adults have nodules that are large enough to palpate on physical examination. Up to 70% of adults develop nodules so small they aren’t palpable and must be visualized with ultrasound examination. The great majority of thyroid nodules are completely benign and pose no health risk whatsoever. A small percentage of thyroid nodules are abnormal and must be addressed. Many nodules are monitored with serial ultrasound evaluations to document whether the nodule enlarges or otherwise changes over time.
The small percentage of thyroid nodules with malignant potential typically have characteristic features that are appreciable by ultrasound examination.
An enlarged thyroid gland is known as a goiter. A small goiter may only be appreciable by your doctor’s physical examination. If neglected, goiters sometimes grow large enough to be easily noticed by a casual glance and therefore become socially awkward. Thyroid goiters can occasionally restrict the esophagus or trachea and thereby impact swallowing or respiratory function.
Most thyroid goiters are benign (non-cancerous). Goiters can arise in hyperthyroid states (overactive thyroid) or in hypothyroid states (underactive thyroid). They can sometimes result from infection or inflammation of the thyroid gland.
If a mass arises anywhere in the neck, an ultrasound evaluation is usually ordered to determine the size, shape, consistency, appearance, and origin of the mass. Care is also taken to look for additional masses, to evaluate adjacent lymph nodes, and to survey other structures in the neck.
Needle biopsy is a procedure in which a thin needle is used to extract sample cells from a thyroid nodule or other abnormal area of the thyroid gland. These cells are then sent to the laboratory for evaluation and to rule out cancerous changes.
Performing an accurate needle biopsy of a relatively small and delicate thyroid nodule without using any guidance can be quite problematic. Because modern ultrasound technology provides high-resolution real-time images, this difficulty has become a thing of the past. The doctor actually watches the needle as he inserts it directly into the region to be sampled. This allows him to determine the most direct route, to avoid adjacent essential structures, and to ensure the sample is actually from the nodule. The result is a much quicker and more reliable technique.
Your ultrasound will be performed in the comfort of your doctor’s office rather than a hospital radiology department.
Be sure to wear comfortable, loose-fitting clothing. Before the test you will need to remove necklaces and other accessories that can block access to your throat and upper chest. When you arrive, the ultrasound technician will likely ask you to remove your shirt, don a loose gown, and lie on your back.
After the ultrasound technician positions you on the examination table, a pillow will be placed under your neck or between your shoulder blades to tilt your head back and expose your throat. The technician will then rub ultrasound gel onto your throat to ensure adequate contact with th skin and to allow the transducer to glide over your skin. The gel may initially feel cold on your throat, but it will warm quickly.
The technician will then direct the transducer over the region to be examined. This should not be painful. Be sure to communicate with the technician should you experience any discomfort.
The technician will guide you through your examination and will likely ask you to shift position as it progresses. Images will be visible on the ultrasound screen. These images will be saved and viewed by the doctor. The ultrasound technician cannot make the diagnosis, so don’t ask them to do so. You will be informed of your examination results by your doctor’s office.
After the examination is complete, the residual gel will be wiped off of your skin. Any residual gel will dry quickly and should not stain or discolor your clothing. As there are no appreciable risks associated with ultrasound examination of the thyroid, you’ll be able to resume routine activities upon completion of the study.
If any nodules are detected within the thyroid gland, they will be examined carefully for features that suggest the nodule to be benign or malignant. In many cases a nodule will exhibit characteristics that strongly suggest the nodule is benign. In other cases, a nodule’s appearance is less reassuring or even worrisome for malignancy. In borderline cases, surveillance with follow-up sonogram may be sufficient, while particularly disquieting nodules may demand needle biopsy to microscopically examine the tissue for malignant changes.
- 76536 – Ultrasound, soft tissues of head and neck (e.g. thyroid, parathyroid, parotid)
- 10022 – Fine needle aspiration with imaging guidance
- 60100 – Core needle biopsy of thyroid
Common ICD-10 CODES
- E01.1 – Iodine-deficiency related multnodular (edemic) goiter
- E04.2 – Nontoxic multinodular goiter
- R94.6 – Abnormal results of thyroid function studies
- E03.9 – Hypothyroidism, unspecified
- I50.22 – Chronic systolic (congestive) heart failure
- E04.1 – Nontoxic single thyroid nodule
- R13.10 – Dysphagia, unspecified
- D34 – Benign neoplasm of thyroid gland
- E05.90 – Thyrotoxicosis, unspecified without thyrotoxic crisis or storm
- E06.0 – Acute thyroiditis
- E06.3 – Autoimmune thyroiditis
- E07.9 – Disorder of thyroid, unspecified
- L04.0 – Acute lymphadenitis of face, head and neck
- C73 -Malignant neoplasm of thyroid gland
- E21.3 – Hyperparathyroidism, unspecified
- E21.0 – Primary hyperparathyroidism
- R63.5 – Abnormal weight gain
- R63.4 – Abnormal weight loss