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POSITRON EMISSION TOMOGRAPHY (PET)
PET images demonstrate the chemistry of organs and other
tissues such as tumors. A radiopharmaceutical, such as
FDG (fluorodeoxyglucose), which includes both sugar (glucose)
and a radionuclide (a radioactive element) that gives
off signals, is injected into the patient and its emissions
are measured by a PET scanner.
A PET scanner consists of an array of
detectors that surround the patient. Using the gamma ray
signals given off by the injected radionuclide, PET measures
the amount of metabolic activity at a site in the body
and a computer reassembles the signals into images. Cancer
cells have higher metabolic rates than normal cells, and
show up as denser areas on a PET scan. In addition, PET
is useful in diagnosing certain cardiovascular and neurological
diseases because it highlights areas with increased, diminished,
or no metabolic activity, thereby pinpointing problems.
PET is a medical imaging modality that inspects all organ
systems of the body, enabling it to search for cancer
in a single examination. PET's ability to measure metabolism
also has significant implications in diagnosing Alzheimer's
disease, Parkinson's disease, epilepsy and other neurological
conditions, because it can vividly illustrate areas where
brain activity differs from the norm.
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