Positron emission tomography (PET) is a test that uses a special type of camera and a tracer (radioactive chemical) to look at organs in the body.
During a PET scan, a radioactive substance called a tracer is typically injected into a vein (usually in the arm), but sometimes it may be inhaled. The tracer usually is a special form of a substance (such as glucose) that can be used (metabolized) by cells in the body.
PET scan pictures do not show as much detail as computed tomography (CT) scans or magnetic resonance imaging (MRI).
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