Definitions

Computed tomography (CT) scan
An x-ray procedure, usually called a CT scan (“cat” scan). It takes a lot of pictures as it rotates around your body and shows detailed cross-sectional pictures of the body. The doctor will have pictures of many slices of the part of your body under study.

Magnetic resonance imaging (MRI)
An imaging technique that uses radio waves and strong magnets instead of x-rays. The body absorbs energy from the radio waves and then releases it in a certain pattern. The type of tissue or disease determines the pattern. A computer translates the pattern into very detailed images of the body. The MRI shows a cross-sectional slice of the body (like a CT scanner) and lengthwise slices as well.

Positron emission tomography (PET) scan
An imaging technique that uses glucose (a form of sugar) that contain a radioactive atom. A small amount is injected into your arm. Then you lie on a PET machine. A special camera detects the radioactivity in any part of your body. Cancer cells tend to absorb large amounts of the radioactive sugar. The PET scan can help your team find any places where cancer may have spread.

June 2006