Parathyroid Scan

What is a parathyroid scan?

A parathyroid scan is a safe and painless imaging procedure healthcare providers use to determine the location of one or more overactive parathyroid gland(s) that are located in an abnormal place in your body. The imaging test is usually an ultrasound or a nuclear scan.

What are parathyroid glands?

Most people have four parathyroid glands, which are small, pea-sized glands that are located behind your thyroid in your neck. In some cases, the parathyroid glands are located along your esophagus or in your chest. These are called ectopic (in an abnormal place) parathyroid glands.

Parathyroid glands are in charge of controlling the amount of calcium in your blood and within your bones by producing parathyroid hormone. Your parathyroid glands are part of your endocrine system.

Sometimes, one or more of your parathyroid glands can release (secrete) too much parathyroid hormone. This is known as primary hyperparathyroidism (PHPT). Too much parathyroid hormone causes the levels of calcium in your blood to rise, a condition known as hypercalcemia.

Why do I need a parathyroid scan?

If you’ve already been diagnosed with primary hyperparathyroidism through a blood test and can have surgery to remove your overactive parathyroid gland(s), your healthcare provider may have you undergo a parathyroid scan to determine the exact location of your overactive parathyroid gland(s). The images from the scan help to make the surgery minimally invasive.

Your provider may also recommend a parathyroid scan if you have ectopic glands to find their location.

What are the types of parathyroid scans?

There are a few different kinds of parathyroid scans. Together, you and your healthcare provider will determine the best option for you.

The two most common types of parathyroid scans are an ultrasound (also called sonography or ultrasonography) and a nuclear scan (also known as a sestamibi scan, MIBI or radionuclide scintigraphy). Sometimes, providers use both imaging tests to get an accurate image of the overactive gland(s).

Ultrasound parathyroid scan

An ultrasound is a safe, accurate medical imaging test that uses sound waves to create real-time pictures or video of internal organs or other tissues, such as blood vessels and glands. Ultrasound enables healthcare providers to “see” details of soft tissues inside your body without making any incisions.

Nuclear parathyroid scan

There are a few different kinds of parathyroid nuclear scans. While the processes are a little bit different for each kind, in general, a nuclear scan involves a safe, radioactive liquid (radiotracer) that your provider injects into a vein. The radioactive liquid flows through your bloodstream, and your parathyroid glands take in (absorb) the liquid.

A special camera then takes images of your parathyroid glands. The overactive parathyroid gland(s) will appear enlarged and “bright” in the image. Most nuclear parathyroid scans involve more than one session of imaging so your provider can compare the pictures to each other.

Types of parathyroid nuclear scans include:

• Single-phase dual-isotope subtraction imaging: This nuclear parathyroid scan requires two different injections of radioactive liquids (radiotracers) into your vein at different times. A special camera takes pictures of your parathyroid glands after each injection.
• Single-isotope dual-phase imaging: For this nuclear parathyroid scan, a provider injects a single radioactive liquid into your vein. A special camera then takes pictures of your parathyroid glands 10 to15 minutes after the injection and again one-and-a-half to three hours later.

There are also different types of cameras and imaging machines that your provider could use during a parathyroid scan. Again, your healthcare team will decide the best option for you. The types of imaging machines include:

• PET (positron emission tomography) scan: A PET scanner is a large machine with a round hole in the middle. Multiple detectors inside the machine record the energy emissions from the radioactive liquid (radiotracer) in your parathyroid glands.
• SPECT (single-photon emission computed tomography imaging) scan: In SPECT, camera heads rotate around your neck to produce detailed, three-dimensional images of your parathyroid glands.
• 4D CT (computerized tomography) scan: A CT scan combines X-rays with a computer that produces many 3D (three-dimensional) images of your parathyroid glands. The fourth dimension in a 4D parathyroid CT scan is time. The radiologist takes the images at specific times due to when and how your parathyroid glands absorb the radioactive liquid.
• MRI (magnetic resonance imaging): MRI uses a large magnet, radio waves and a computer to produce detailed images. It doesn’t use X-rays (radiation).

How do I prepare for a parathyroid scan?

Your healthcare provider will let you know if you need to follow specific instructions before your parathyroid scan, like if you’re able to eat or drink before the scan.

You’ll likely have to remove jewelry and accessories before the scan because they might interfere with the imaging process.

If you’re undergoing a nuclear scan, it’s essential to tell your healthcare provider if you’re pregnant, think you might be pregnant or if you’re breastfeeding (chestfeeding).

What should I expect during a parathyroid scan?

The process for your parathyroid scan depends on what type of scan you’re getting.

Ultrasound parathyroid scan process

If you’re undergoing an ultrasound as your parathyroid scan, you’ll typically lay on your back on an exam table with a shoulder roll or pillow under your neck.

The ultrasound technician (the person performing the ultrasound) will then do the following:

• Apply gel: You’ll have a small amount of water-soluble gel on the skin of your neck. This gel doesn’t harm your skin or stain your clothes.
• Use the ultrasound probe (transducer): The technician will move a handheld instrument that looks like a microphone over the gel. The technician will move the probe around on your skin. This is how the technician takes “pictures” of your parathyroid glands.
• Ask you to hold still: Being very still can help create clearer pictures.
• Clean your skin: The technician will wipe off any remaining gel on your skin once they’ve finished the test.

Nuclear parathyroid scan process

There are a few different kinds of parathyroid nuclear scans. Your healthcare provider will give you specific details of what to expect. Don’t be afraid to ask them questions.

In general, a nuclear scan involves a safe, radioactive liquid (radiotracer) that a provider injects into one of your veins. This liquid is safe, but you may feel a slight pinch when your provider injects it with a needle.

You’ll then lay on your back on an exam table while your provider uses an imaging machine to take images of your parathyroid glands.

You shouldn’t have any side effects after your nuclear parathyroid scan, and you’ll be able to drive home after the test.

How long does a parathyroid scan take?

An ultrasound usually takes 30 minutes to an hour.

The entire nuclear parathyroid scan procedure generally takes two to five hours, depending on the specific type of scan.

Are there any side effects or risks to getting a parathyroid scan?

There are no side effects or risks to getting an ultrasound parathyroid scan.

Since a nuclear parathyroid scan uses a very small amount of radioactive liquid (radiotracer), your exposure to radiation is low. Because of this, the benefits of the scan in determining the location of your overactive parathyroid gland before surgery outweigh the very low radiation risk. However, you must tell your healthcare provider if you’re pregnant, think you might be pregnant or are breastfeeding/chestfeeding before getting a nuclear scan.

Does a parathyroid scan hurt?

An ultrasound parathyroid scan is painless.

The nuclear parathyroid scan is also painless except for the radioactive liquid injection (radiotracer) into your vein. You will experience a small poke and might experience pain when the specialist first injects the radioactive liquid.

When can I expect the results from my parathyroid scan?

Depending on the type of parathyroid scan you have, a radiologist or other healthcare provider specially trained in nuclear scans will interpret the images and send a report to your doctor and surgeon. Your healthcare team will then schedule an appointment with you to go over the results.

A note from Cleveland Clinic:

Parathyroid scans are a safe and helpful tool for your surgeon to plan for the surgical removal of your overactive parathyroid gland(s). Knowing exactly where the overactive gland(s) are allows the surgery to be minimally invasive. Make sure you get your parathyroid scan from an expert who knows how to perform the scans properly and safely.