Updated June 09, 2015.

Definition:

A PET scan is a method of taking an image of the brain. PET stands for positron emission tomography, which provides both two- and three-dimensional pictures of brain activity by measuring radioactive isotopes (elements attached to molecules that are injected into the bloodstream so they can flow to organs such as the brain). PET scans are used to detect tumors and damaged tissue, measure metabolism, and view how blood flows in the brain.

PET scans can help diagnose Alzheimer's by identifying or ruling out certain causes of Alzheimer's-like symptoms.