How Does PET/CT imaging work?

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PET/CT Imaging at the Swedish Cancer Institute

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During a PET/CT procedure, one machine does both the PET & the CT scans and shows each separately plus a third set of co-registered (or fused) images. The yield is an image showing an anatomically localized area (CT) of metabolic activity (PET).

The metabolic imaging (PET) component of the technology is based on a long-understood concept in cancer biology - that cancer cells are metabolically more active than normal cells: they grow, divide, and consume sugars more aggressively. The current generation of PET scans uses fluorodeoxyglucose, which is 2-deoxy-D-glucose labeled with fluorine-18, a positron emitter. This radioactive substance is injected into the patient. The substance then essentially “goes where glucose goes, which is into metabolically active cells”. Once cancer cells take up the substance, the trapped fluorodeoxyglucose gives off photons that the PET camera can “see” and the information is translated on the screen into an accurate image of the tumor’s glucose uptake.

The anatomical imaging (CT) component of the technology combines a series of x-ray views taken from many different angles to produce cross-sectional images of the bones and soft tissues inside the body.