http://www.ck12.org Chapter 24. Nuclear Chemistry
the plaque growth.
The compound known as "Pittsburgh compound B" is often used to identify areas of plaque in the brain. The
C-11 atom bound to the nitrogen has a half-life of just 20.38 minutes, so administration and detection must be
accomplished very quickly.
FIGURE 24.15
The label attaches to plaques in the brain and can be observed using a PET scanner.
FIGURE 24.16
The computer translates the intensity of the decay from the radioactive isotope into a color scale, with red indicating
a high level of radioactivity and yellow indicating somewhat less activity. We can see from the scans that the
cognitively healthy individual shows the presence of very little plaque in the brain, whereas the individual with
Alzheimer’s has high concentrations of beta-amyloid in numerous areas of the brain.
Other studies have used PET scans to look at certain regions of the brain in drug addicts. One of the theories about
drug addiction involves activity related to the molecule dopamine, a chemical that helps carry certain nerve impulses
from one brain cell to the next. Studies on dopamine activity in the brain have been helpful in understanding the
biochemical processes behind addiction.