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PET (Positron Emission Tomography)

Introduction

An imaging technique using positively charged particles (radioactive positrons) to detect subtle changes in the body's metabolism and chemical activities. A PET scan provides a color-coded image of the body's function, rather than its structure.

During a PET scan, a substance called a tracer that produces radioactive positrons either is injected into a vein or inhaled as a gas. This tracer is typically a chemical that is normally found in the body (carbon, nitrogen, oxygen) that has been altered to allow it to emit positrons. Once the tracer enters the body, it travels through the bloodstream to a specific target organ, such as the brain or heart.  The PET scan must be done immediately after the tracer has been given because the positron-emitting traces usually decays (loses its positrons) rather quickly.