How do you utilize FDG PET in the evaluation of dementias?

FDG PET is a regional map of glucose utilization in the brain. It tends to show reduced activity in specific areas in early Alzheimer's disease. It can complement MRI, which shows patterns of atrophy, rules out strokes, etc. Neither test is biologically specific for AD, which would require an amyloid PET and/or tau PET. A less expensive approach is to use biomarkers, amyloid, and various tau peptides in CSF. Soon, the markers will be identifiable in blood.