| Positron
emission technology (PET) evaluates the metabolic makeup of
a lesion in the brain. Typically, glucose and methionine are
used during a PET scan. All cells in the body use glucose for
energy and metabolism. Tumors have higher metabolism than other
cells, and therefore take up more glucose than other cells.
During a PET scan, the patient is given radioactive fluoro-deoxyglucose,
which is a radioactive labeled glucose molecule. The tumor cells
take this up faster than other cells, and therefore emit more radioactivity.
They therefore appear "brighter" on a PET scan.
PET scans are good for looking at metabolism,
but poor at looking at anatomical structure. On the other
hand, magnetic resonance scans are good at looking at anatomy, but
poor at metabolism and function. When the two are combined,
such as in a coregistered image (where the two are superimposed),
one can see the best of form and function. In the scans seen
here, a magnetic resonance image is seen on the left, a PET scan
seen in the middle, and the coregistered images on the right.
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