What does a PET scan observe?

A PET scan, or Positron Emission Tomography scan, primarily observes biochemical changes in the brain during various activities. It does this by using a radioactive substance known as a tracer, which is injected into the bloodstream. As the tracer moves through the body, it emits positrons that can be detected by the scanner. The areas of the brain that are active during specific tasks will absorb more of the tracer, allowing for a visualization of biochemical processes, such as glucose metabolism, and providing insights into how different regions of the brain work during various activities.

This ability to monitor metabolic activity distinguishes PET scans from other imaging techniques. For example, electrical impulses in neurons relate more to methods like EEG, which measure brain wave activity, while functional imaging of soft tissue can be done through techniques like MRI. Similarly, the observation of magnetic resonance of brain structures, which is characteristic of MRI, focuses more on structural imaging rather than the biochemical processes that PET scans highlight.