What Is a SPECT Scan?

What to expect when undergoing this test

SPECT scans provide a non-invasive way for doctors to evaluate the health of certain parts of your body, most commonly the heart, brain, and bones.

SPECT stands for single-photon emission computerized tomography. The scan produces three-dimensional images that allow your doctor to see what’s going on inside your organs from different angles. SPECT scans fall under the category of nuclear medicine, according to the National Institute of Biomedical Imaging and Bioengineering. The process involves the use of radioactive materials and a specially designed gamma camera.

Nuclear scans use radioactive tracers, which are carrier molecules that are bonded with radioactive atoms, to evaluate, diagnose, and treat a range of illnesses. Different tracers perform different functions, and the doctor chooses the tracer that’s appropriate for you depending on your symptoms or disease that’s being be evaluated.

What makes SPECT scans different from other methods of imaging is that the scan can show how well certain organs are functioning. For example, SPECT scans provide information about how well your heart is pumping, if your heart is getting enough blood, or if the blood flow is precluded by a disease process like coronary artery disease (CAD).

The SPECT scan may be beneficial is when evaluating the brain. The images made by the SPECT scan can help pinpoint the location of seizures in people with epilepsy and assess whether there's sufficient blood flow to different areas of the brain.

what to expect during a SPECT scan
Illustration by Emily Roberts, Verywell

Purpose of Test

SPECT scans can cost-effectively be used in a variety of ways, which is why they're readily available at most hospitals, clinics, and imaging centers. Some of the reasons your doctor may choose to order this test include:

  • Cardiac conditions
  • Brain and neurological conditions
  • Bone disorders

Cardiac Conditions

Radioactive tracers during the SPECT scan can capture how well your heart is working, and, ultimately, disease processes that may be going on in the heart such as:

  • Narrowing of the arteries
  • Clogged arteries
  • Scar tissue due to heart attacks
  • How well your heart is pumping blood
  • Whether surgical procedures, such as bypass surgeries or other surgeries, were successful

Brain and Neurological Conditions

SPECT scans can be used to gather information about changes that occur in brain function due to disease processes, including:

Bone Disorders

SPECT scans can be useful in bone disorders because areas of concern will often light up. The conditions that can be explored using this technology include:

  • Less visible bone fractures such as stress fractures
  • Bone cancer or cancer that has metastasized to areas of bone
  • Bone infections

Risk and Contraindications

Most people tolerate SPECT scans well, but there may be some instances where the test would be ill-advised. Your doctor may opt not to perform this test for the following reasons:

  • You’re pregnant or nursing. The tests use a low dose of radiation, which is not recommended for pregnant women. If you’re breastfeeding, you may be required to wait a certain amount of time before nursing to allow your body time to excrete the radioactive tracer.
  • If you're allergic to the tracer. Though unusual, this kind of allergy is possible, and you shouldn't have the scan if you have a known allergy to the tracer. If you have an allergic reaction while undergoing the scan, know that the healthcare professionals around you are equipped to handle the situation.

Worried about the radiation?

Since the SPECT scan does use a low dose of radiation, talk with your doctor if you have any concerns about your risk of exposure. No long-term health risks have been associated with using this method of imaging. 

Before the Test

The things you may need to do to prepare for the scan can differ depending on the reason you're having the scan. Your healthcare team should give you specific guidelines for your test. In general, you’ll find the following recommendations helpful:

Timing

Ask your medical team about the amount of time you should set aside for the scan. Some scans take about 30 minutes. Others may require more or less time depending on the reason for the SPECT scan.

Location

Testing may be done in a hospital, clinic, or imaging center. Typically, the scan will be done by a medical team that specializes in nuclear medicine.

What to Wear

You can wear what you want for the procedure, but you’ll likely be asked to change into a gown before the scan. You may find that casual, loose-fitted clothing is a comfortable choice for the test. Additionally, leave metal items, like watches, jewelry, and earrings, at home.

Food and Drink

Your healthcare team will let you know if the scan requires you to avoid certain foods or drinks. For example, if you have a SPECT scan for cardiac reasons, you may need to avoid caffeine for several hours before the test.

What to Bring

Bring your insurance card, a form of identification, and any paperwork you’ve been asked to fill out before the scan.

Other Considerations

Make sure your doctor has a current list of all the medications, including over-the-counter products and supplements, that you’re taking. Your doctor may want you to stop taking certain ones before the procedure. Also, let your doctor know if you’re pregnant or nursing.​

During the Test

The test consists of two parts: injecting the radioactive tracer and the SPECT scan itself.

The Radioactive Tracer

An intravenous (IV) line will be inserted into your arm. The radioactive tracer will then be injected via the IV. You may feel a cold sensation as the tracer flows into your bloodstream. Once the tracer has been injected, your technician or doctor will instruct you on how long you need to wait before beginning the scan so that the tracer can be fully absorbed into your body.

The wait could be as short as 20 minutes. In some cases, though, it could take hours or days for the absorption to happen. Your medical team will provide you with information on this process.

The SPECT Scan

During the scan, you’ll be asked to lie on a table. The gamma camera will rotate around your body, creating three-dimensional images of your internal organs and tissues. The scan doesn’t cause pain, so if you experience pain or discomfort, be sure to let your doctor or technician know so that they can help you get more comfortable.

After the Test

Once the scan is completed, you can usually resume your daily activities right away. Staying hydrated will help your body flush out the remaining portion of the radioactive tracer over the next couple of days. Special instructions may be given to you if you’re nursing, as you may be required to hold off nursing for a period of time while the tracer exits your system.

Interpreting Results

A radiologist or nuclear medicine physician will evaluate the results of your SPECT scan and report the findings to your doctor, so your scan results aren’t likely to be ready immediately. Your SPECT scan images will show bright or dark areas, either in color in grayscale, where the radioactive tracer has been absorbed by your organs and tissues.

Your doctor or a member of their staff will contact you to talk about the results and whether additional testing is needed. One thing to keep in mind is that you can request copies of your SPECT scan images and the report for your records, or if you’d like to get a second opinion.

A Word From Verywell

Going through the testing process can be a bit nerve-wracking. To help you feel more at ease, make sure your doctor takes the time to address your fears or concerns. This will go a long way toward helping you feel more comfortable.

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