Posted October 2, 2022 by Anusha ‐ 4 min read

A single-photon emission computerized tomography (SPECT) scan lets your doctor analyze your body's organs, tissue and bones. A SPECT scan is a type of nuclear imaging test, which means it uses a radioactive substance and a special camera to create 3D pictures.

Uses of SPECT scan

Brain disorders

A SPECT test creates a detailed, 3D map of the blood flow activity in your brain, which can be helpful in determining which parts of the brain are being affected by:

  • Clogged blood vessels - SPECT scanning can detect altered blood flow in the brain and help diagnose or evaluate certain vascular brain disorders, such as moyamoya disease, a condition in which the arteries in the brain become blocked or narrowed.

  • Seizure disorders - A SPECT scan can help diagnose and treat seizure disorders, such as epilepsy, by pinpointing the area of seizure activity in the brain.

  • Parkinson’s disease - In rare cases, your doctor may suggest a specific SPECT scan called a dopamine transporter scan to help confirm a diagnosis of Parkinson’s disease, a progressive neurological disorder that affects movement.

Some medical institutions may use SPECT scanning to help evaluate other brain conditions, such as dementia or head trauma.

Heart problems

Because the radioactive tracer highlights areas of blood flow, SPECT can check for:

  • Clogged coronary arteries - If the arteries that feed the heart muscle become narrowed or clogged, the portions of the heart muscle served by these arteries can become damaged or even die.

  • Reduced pumping efficiency - SPECT can show how completely your heart chambers empty during contractions.

Bone disorders

  • Areas of bone healing or cancer progression usually light up on SPECT scans, so this type of test is being used more frequently to help diagnose hidden bone fractures.

  • SPECT scans can also diagnose and track the progression of cancer that has spread to the bones and help identify sites for bone biopsy.

Procedure of SPECT scan

During the test

SPECT scans involve two steps: receiving a radioactive injection (called a tracer) and using a SPECT machine to scan a specific area of your body.

Receiving a radioactive substance

  • You’ll receive a radioactive substance through an intravenous (IV) infusion into a vein in your arm.

  • The tracer dose is very small, and you may feel a cold sensation as it enters your body.

  • You may be asked to lie quietly in a room for 20 minutes or more before your scan while your body absorbs the radioactive tracer.

  • In some cases, you may need to wait several hours or, rarely, several days between the injection and your SPECT scan.

  • Your body’s more active tissues will absorb more of the radioactive substance.

  • For instance, during a seizure, the area of your brain causing the seizure may retain more of the radioactive tracer, which allows doctors to pinpoint the area of your brain causing your seizures.

Undergoing the SPECT scan

  • The SPECT machine is a large circular device containing a camera that detects the radioactive tracer your body absorbs.

  • During your scan, you lie on a table while the SPECT machine rotates around you.

  • The SPECT machine takes pictures of your internal organs and other structures.

  • The pictures are sent to a computer that uses the information to create 3D images of your body.

After the test

  • Most of the radioactive tracer leaves your body through your urine within a few hours after your SPECT scan.

  • Your doctor may instruct you to drink more fluids, such as juice or water, after your SPECT scan to help flush the tracer from your body.

  • Your body breaks down the remaining tracer over the next few days.

Results of SPECT scan

  • A radiologist or doctor with advanced training in nuclear medicine will analyze the results of your SPECT scan and send them to your doctor.

  • Pictures from your scan may show colors that tell your doctor what areas of your body absorbed more of the radioactive tracer and which areas absorbed less.

  • For instance, a brain SPECT image might show a lighter color where brain cells are less active and darker colors where brains cells are more active.

  • Some SPECT images show shades of gray, rather than colors.

Risks of SPECT scan

For most people, SPECT scans are safe. If you receive an injection or infusion of radioactive tracer, you may experience:

  • Bleeding, pain or swelling where the needle was inserted in your arm

  • Very rarely, an allergic reaction to the radioactive tracer

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