SPECT Scanning

A type of radionuclide scanning that produces images of blood flow to tissues

First used in the 1970s for research, single photon emission computerized tomography (SPECT) scanning is now used for imaging. This technique is a specialized type of radionuclide scanning and provides information on blood flow to various body tissues.

SPECT scanning is extremely sensitive and can target certain organs more easily than ordinary radionuclide scanning procedures. However, only a few centres offer SPECT scanning because expensive equipment is involved and specialist technicians are needed.

How does it work?

Before a SPECT scan, a radioactive substance (radionuclide) is intravenously injected. Radionuclides are distributed in the blood and are taken up by specific tissues. The more blood flowing through the tissues, the more radionuclide is taken up. The radionuclide emits radiation in the form of particles called photons. Photons are detected outside the body by a rotating camera, which can move through 360°. A computer converts the information from the camera into cross-sectional images, on which the different tissues or organs can be coloured to assist identification. SPECT scanning can be used to produce both vertical and horizontal cross sections through the body, and the data can also be manipulated by a computer to produce three-dimensional images.

SPECT scans of heart muscle

These SPECT scans show horizontal cross sections through the heart. Before surgery, the absence of radionuclide in part of the heart indicates there is no blood flow in that area. Surgery has restored the blood flow.

What is it used for?

SPECT scanning is mainly used to find out how well an organ is functioning by looking at the supply of blood to its tissues. SPECT scanning is particularly useful for assessing the function of the heart and brain, especially for investigating epileptic seizures (see Epilepsy).

What are the risks?

SPECT scanning presents no immediate risks to health, but it does involve radioactive substances and therefore has the potential to damage the body cells, which may increase the risk of cancer in later life. However, SPECT scanning uses only small amounts of radionuclides, which break down quickly in the body.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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