The thyroid gland is a small, butterfly-shaped gland located in the neck that produces hormones that regulate metabolism. Thyroid disease is common, affecting more than 12% of Americans at some stage of their lives. Some of the most prevalent types of thyroid disease include:
Hypothyroidism – With hypothyroidism, the thyroid gland fails to produce enough thyroid hormones, often causing symptoms like fatigue, weight gain, cold intolerance, hair loss, and even depression. Hypothyroidism can be caused by iodine deficiency, an autoimmune disorder like Hashimoto's thyroiditis, or radiation therapy to the neck.
Hyperthyroidism – Here, the thyroid gland produces excess hormones, leading to symptoms such as unnatural weight loss, an accelerated heart rate, tremors, and feelings of restlessness or anxiety. Hyperthyroidism can be caused by thyroid cancer, nodules on the thyroid, or an autoimmune disorder such as Graves' disease.
Thyroiditis – Thyroiditis is inflammation of the thyroid gland, which can be caused by infection, an autoimmune disorder, or radiation therapy. Symptoms of thyroiditis include pain, swelling, tenderness in the neck, and others that can mimic hypothyroidism or hyperthyroidism.
Thyroid nodules – Solid or fluid-filled growths or lumps can form on or in the thyroid gland. Most nodules are benign and may not produce symptoms other than mild swelling, and usually don’t require treatment. However, some nodules may be large enough to cause issues, including producing additional hormones, creating hyperthyroidism. Only about 10% of thyroid nodules turn out to be malignant.
Thyroid cancer – There are different types of cancer of the thyroid gland, most commonly papillary thyroid cancer and follicular thyroid cancer. Less common are Hurthle cell carcinoma, medullary thyroid cancer and anaplastic thyroid cancer. Thyroid cancer can cause a lump, nodule or swelling in the neck, and may produce symptoms associated with hypothyroidism or hyperthyroidism. When caught and treated while still localized, the most common types of thyroid cancer have a survival rate exceeding 99.5%.
Why Did My Doctor Recommend a Thyroid Nuclear Scan?
Thyroid disease can be diagnosed using a range of tests, such as blood tests to measure thyroid hormone levels, and imaging studies to evaluate nodules and look for cancer.
While there are various imaging tests commonly used to image the thyroid gland, like ultrasound, CT and MRI, a thyroid nuclear scan is often the preferred imaging method because of its ability to produce highly detailed information about both the form and function of the thyroid. It enables your radiologist and referring clinician to evaluate thyroid structure, activity and function at a cellular level, and capture images based on body chemistry, making it especially beneficial when investigating tumors, discovering cancer, determining if and where cancer has spread, and preparing any treatment.
Thyroid nuclear scans are used to:
Study a nodule to help determine if the thyroid gland is functioning normally or is overactive or underactive
Diagnose hyperthyroidism or Graves' disease and assess any gland overactivity
Look for abnormal cell activity, which may indicate the presence of cancer
Monitor the effectiveness of thyroid cancer treatment
See whether thyroid tissue is functioning normally post-treatment
How Is a Thyroid Nuclear Scan Performed?
Nuclear scans are painless, noninvasive tests that utilize a small amount of radioactive material, called a radiotracer, which diseased cells typically absorb at different rates than healthy cells. So-called “hot spots” indicate increased cell activity, while “cold spots” suggest reduced activity. Either can indicate possible cancer or certain other diseases.
During your first visit, you will be asked to swallow a small amount of radioactive iodine in capsule form. After about 4 hours, the radiotracer will have had time to collect in the thyroid and related areas. You will then be ready for the first scan to see how much radioactive iodine was absorbed. For the scan itself, you simply lie on your back on the imaging table while a series of images are taken. The radiotracer emits gamma rays that are recognized by a specialized gamma camera, which sends signals to a computer to create multidimensional pictures. The imaging procedure usually takes under an hour.
The next day, you will be asked to return for the remainder of the uptake procedure, which takes only about 5-10 minutes. You are then free to resume your day as normal.
Your RAO Board-certified, subspecializing radiologist and referring clinician will review the images to evaluate your thyroid gland’s function and structure and use this information to make a diagnosis or suggest further testing. Your clinician will contact you with your results and make any necessary recommendations for follow-up or treatment.
Is a Thyroid Nuclear Scan Safe?
The radiotracer does contain a small dose of radiation, about that of a routine x-ray. It typically evacuates the body through the urine or stool anywhere from a few hours to a few days. Because of the low dose and quick exit of radioactive material, nuclear scans are considered safe for most people.
RAO’s Medical Imaging Center at Windsor Oaks is accredited in Nuclear Medicine by the American College of Radiology for safety, accuracy and best practice standards, for diagnostic care you can feel good about.
