Brain scans used in the diagnosis of Alzheimer's disease.

Brain scans known as fluorodeoxyglucose PET, also called FDG PET, may be used to diagnose Alzheimer's disease. FDG PET scans show areas of the brain where nutrients aren't properly used for energy, known as metabolism. The scans in this image show a healthy brain, a brain with mild cognitive impairment and a brain with Alzheimer's disease. Areas that are black and blue represent healthy brain metabolism. Areas that are green, yellow and red represent worsening brain metabolism as the disease gets worse.