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PET Scans

A technique that is especially useful in studying the processes in the brain.

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A Peek Inside the Brain

A Peek Inside the Brain

Credit: Dr. Giovanni Dichiro
Source: https://visualsonline.cancer.gov/details.cfm?imageid=1755
License: CC BY-NC 3.0

How do we know what is going on in the brain? We can take X-rays to look at brain structure or we can open up a skull and see the brain directly. But these are static pieces of information. Can we see the brain in action? Using developments from research in radioactivity, we can “watch” a person think.

Amazing But True!

  • Positron emission tomography (PET) is a technique that allows us to see the brain in action. We can inject a radiolabeled compound into the bloodstream and see how the brain uses that compound.
  • Credit: liz west
    Source: http://www.flickr.com/photos/calliope/7694882446/
    License: CC BY-NC 3.0

    PET scan machine [Figure2]

  • The brain uses about 25% of the glucose present in the blood at any given time. If we label glucose with a radioactive material, different parts of the brain will use the glucose, depending on the specific brain activity.
  • A person using amphetamines or cocaine (for example) will show different patterns of brain activity than a person who is not using those substances.
  • There are a number of diseases of the brain that can be detected using PET scans. The first clinical application in the 1950s involved patients with brain tumors. Radiolabeled chemicals that specifically interact with tumor tissue will be selectively absorbed by the cancer cells, allowing visualization of the tumor.
  • In the disorder known as Parkinson’s disease, neurons that respond to the neuro transmitter dopamine are known to be deficient. When labeled dopamine is injected into these patients, a lower amount of dopamine is taken up by the brain.


Can You Apply It

Using the links below, learn more about PET scanning. Then answer the following questions.

  1. What is the difference between CT scanning and PET scanning?
  2. How can a PET scan provide useful information after chemotherapy for a cancer?
  3. List four different radioisotopes used in PET scans.

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    Image Attributions

    1. [1]^ Credit: Dr. Giovanni Dichiro; Source: https://visualsonline.cancer.gov/details.cfm?imageid=1755; License: CC BY-NC 3.0
    2. [2]^ Credit: liz west; Source: http://www.flickr.com/photos/calliope/7694882446/; License: CC BY-NC 3.0

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