Positron emission tomography
From Psy3242
History
In the early 1950's David Kuhl and Roy Edwards introduced the idea of positron emission tomography (PET). The first time a PET scan was used on two human beings was by Abass Alavi in August 1976 at the University of Pennsylvania. In the 1970's and 80's the PET scan was mainly used for research only and beginning in the 1990's the PET scan became public. Today PET is a major diagnostic imaging modality used predominantly in determining the presence and severity of cancers, neurological conditions, and cardiovascular disease. It is currently the most effective way to check for cancer recurrences.
PET is an important research tool to map normal human brain. It can illustrate areas where brain activity differs from the norm. PET scans allow one to observe blood flow or metabolism in any part of the brain. In a PET scan, the subject is injected with a very small quantity of radioactive glucose. The PET then scans the absorption of the radioactivity from outside the scalp. Brain cells use glucose as fuel, and PET works on the theory that if brain cells are more active, they will consume more of the radioactive glucose, and if less active, they will consume less of it. Therefore if a patient is given a task or asked a question that stimulates an area of the brain, the area that is activated will light up. Then the information is sent to a computer to show the levels of activity. PET scans allow researchers to look at a 'cross-sectional' layers of the brain. This allows the researcher to look at the deeper parts of the brain which earlier scanning techniques have not been able to do. PET is currently one of the most popular scanning techniques.
