A SPECT scan, short for Single-photon Emission Computerized Tomography, allows your doctor to examine the functioning of internal organs of your body. It is a special type of nuclear imaging test that utilizes radioactive material and an advanced camera to generate images of your organs.
In comparison to x-rays that display the internal structures of your body in two-dimensional (2-D) image format, a SPECT scan generates 3-D images that display the actual working of the organs. For example, a SPECT scan can display the movement of blood to your heart or areas inside your brain that may be more or less active.
Why a SPECT scan is carried out?
A SPECT scan may be recommended to detect or monitor a variety of medical conditions and diseases such as:
- Brain disorders – including stroke, seizure and Alzheimer’s disease
- Heart problems – including chest pain, heart attack and arterial blockages in the heart
- Various forms of cancer – such as primary tumors and those that have spread to other parts of the body (metastasized)
Risks involved
SPECT scans are considered safe for most people. In case a radioactive tracer is administered through injection or infusion, you may experience:
- Pain, swelling or bleeding at the specific spot on your arm where the needle was inserted
- An allergic reaction induced by the radioactive tracer, although this occurs rarely.
A SPECT scan is not considered safe for pregnant or breast-feeding women because there are chances that the radioactive tracer may affect the developing fetus or the new-born baby. A pregnancy test may be required prior to a SPECT scan in case of women having reached childbearing age.
Radiation risks
The least possible amount of radiation is used during a SPECT scan. Radiation levels during such scans are similar to what you may be exposed to over a period of one year in the natural environment. If you are concerned about radiation exposure associated with a SPECT scan, you need to talk to your doctor.
What to expect?
During a SPECT scan
SPECT scans usually involve a two-step procedure – the infusion or injection of radioactive dye (knows as radioactive tracer) and scanning of specific parts of your body using a SPECT machine.
Receiving the radioactive substance
The radioactive substance will be administered to you through an injection or an intravenous (IV) infusion into one of the veins in your arm. In specific cases, you may be asked to inhale the radioactive substance through your nose.
The radioactive substances are processed inside your body wherein the most active tissues absorb more of the substance. For example, the region inside your brain that may be responsible for the seizures will absorb more of the radioactive substance. This will make it easier for doctors to pinpoint the region inside your brain causing the seizures. It is also likely that cancer cells will absorb more of the radioactive substance in comparison to normal cells because cancer cells generally grow at a much faster rate than normal cells.
The type of radioactive substance you will be administered will depend on the specific procedure being followed and the part of your body that is to be scanned. Prior to the scan, you may have to lie down quietly in a room for around 15 minutes or more to allow proper absorption of the radioactive substance.
Taking the SPECT scan test
The health care team members will position you on a table in the desired manner in the room where your SPECT scan test is to be conducted.
A large circular device, a SPECT machine has a special camera known as a gamma camera that measures the amount of radioactive substance absorbed by your body. The SPECT machine will rotate around you during the scan while you are lying on the table. It then shoots pictures of organs and other internal structures in your body. The pictures are then processed by a computer to generate 3-D images of the body.
The duration of the SPECT scan will depend on the underlying objective for your procedure. In specific cases, you may be required to take more scan tests, a few hours or days later.
After the SPECT scan test
In just a few hours after the SPECT scan, most of the radioactive substance is flushed out by the body through the urine. You may be instructed to increase your intake of fluids, for example, water or juice, to help your body remove the radioactive substance. What may be left behind is broken down by your body in one or two days.
Your doctor will evaluate results derived through the SPECT scan. Pictures obtained from the scan may display specific colors, allowing your doctor to pinpoint areas in your body that absorbed more of the radioactive substance in comparison to other areas. For example, an image generated by a SPECT machine may display lighter colors for areas inside the brain where cells are less active and darker colors for areas with more active cells. Some SPECT images display shades of gray instead of colors.
Ask your doctor how long you may have to wait for the SPECT scan results.
