PET stands for Positron Emission Tomography.  PET scanning can produce high quality pictures of different processes in your body.  For brain imaging, PET can be used to take pictures of how your brain uses glucose, or sugar.  Glucose is the source of energy for your brain.   Scientists have learned that there are abnormal patterns of glucose use in the brains of patients with Alzheimer’s disease, and in some older people.

How does PET work? 
Scientists (called technologists) at the PET center make a special form of glucose that is labeled with radioactivity.  This is called fluorodeoxyglucose, or FDG.  The FDG is injected through a small needle into a vein in a person’s arm, and the PET scanner picks up this labeled.  Pictures are taken every few seconds during the time that a person is in the scanner, which shows how the brain is processing during that time period.

PET in Alzheimer’s Disease
The PET scans being used in ADNI measure the brain's rate of glucose metabolism using the tracer [18F]Fluorodeoxyglucose.  In Alzheimer's disease, characteristic brain regions show decreased glucose metabolism, specifically regions in the temporal and parietal lobes.  We hope that following these changes over time in people with AD, people with normal aging changes, and those with mild cognitive impairment will enable us to track the disease progression as a potential biomarker for clinical trials.  PET could also become a potential biomarker used to predict who might later develop Alzheimer’s disease.