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Home > Health Library > Single Photon Emission Computed Tomography (SPECT)
Single photon-emission computed tomography (SPECT) is a test that uses a special type of camera and a tracer (a radioactive substance in liquid form) to look at organs or bones in the body. During the test, the tracer is put into a vein (intravenous, or IV) in your arm. Sometimes it's taken by mouth or inhaled through the nose.
The tracer moves through your body, where it may collect in the specific organ or tissue. The tracer gives off tiny bits of radiation called gamma rays. The camera records the gamma rays. Then a computer turns the recording into 3-dimensional pictures. SPECT scan pictures show how organs are working.
Other types of scans, such as computed tomography (CT) scans or magnetic resonance imaging (MRI) show more details of the organs themselves. The SPECT picture may be matched with those from a CT scan to get more detailed information about where the tracer is located.
A SPECT scan is often used to evaluate brain, head, and neck problems; to look at blood flow to the heart; to examine bones; and to diagnose problems in other organs such as the gall bladder, liver, spleen, and kidneys.
A SPECT scan is done to:
A single photon-emission computed tomography (SPECT) scan is done in a hospital nuclear medicine department or at a special radiology center by a radiologist or nuclear medicine specialist and a technologist. You will lie on a table that is hooked to a large scanner, cameras, and a computer.
The radioactive tracer is usually given in a vein (IV). You may need to wait as long as an hour for the tracer to move through your body. During this time, you may need to avoid moving and talking.
The SPECT scanner is a large machine that scans your body. It has two cameras that rotate slowly around your body. They will be very close to your body but should not touch you. The scanned pictures are sent to a computer screen so your doctor can see them. Many scans are done to make a series of pictures.
It's very important to lie still while each scan is being done. At some medical centers, a CT scan will be done at the same time.
For a SPECT scan of the brain, you will lie on a bed. You may be asked to read, name letters, or tell a story, depending on whether speech, reasoning, or memory is being tested. During the scan, you may be given earplugs and a blindfold (if you don't need to read during the test) to wear for your comfort.
If you are having a SPECT scan of your heart, electrodes for an electrocardiogram (EKG, ECG) will be put on your body. During the test, you will be alone in the scanner room. The technologist will watch you through a window. You will be able talk to him or her at all times through a two-way intercom.
The test takes 1 to 3 hours. You may need to return for follow-up scans.
After the test, drink lots of fluids for the next 24 hours to help flush the tracer out of your body.
Be careful with body fluids. Flush toilets and wash hands well right after you use the bathroom. Avoid using a urinal.
You won't feel pain during the test. The table you lie on may be hard, and the room may be cool. It may be difficult to lie still during the test.
You may feel a quick sting or pinch when the IV is put in your arm. The tracer is unlikely to cause any side effects. If you don't feel well during or after the test, tell the person who is doing the test.
You may feel nervous while the SPECT scanner moves around you.
Allergic reactions to the tracer are very rare.
In rare cases, you may have some soreness or swelling at the IV site where the radioactive tracer was put in. If so, apply a moist, warm compress to your arm.
Anytime you're exposed to radiation, there's a small chance of damage to cells or tissue. That's the case even with the low-level radioactive tracer used for this test. But the chance of damage is very low compared with the benefits of the test.
Most of the tracer will leave your body through your urine or stool within a day. So be sure to flush the toilet right after you use it, and wash your hands well with soap and water. The amount of radiation in the tracer is very small. This means it isn't a risk for people to be around you after the test.
Single photon-emission computed tomography (SPECT) is a test that uses a special type of camera and a tracer (a radioactive substance in liquid form) to look at organs in the body.
The radiologist may discuss preliminary results of the SPECT scan with you right after the test. Complete results are usually available in 1 to 2 days.
Brain (such as epilepsy, dementia, stroke):
You may not be able to have the test or the results may not be helpful if:
Current as ofMarch 28, 2019
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineAdam Husney MD - Family MedicineHoward Schaff MD - Diagnostic Radiology
Current as of:
March 28, 2019
Medical Review:E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & Howard Schaff MD - Diagnostic Radiology
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