PET of the cerebral metabolic rate of glucose is increasingly used to support the clinical diagnosis in the examination of patients with suspected major neurodegenerative disorders, such as Alzheimer's disease. PET has been reported to have high diagnostic performance, especially, very high sensitivity in the diagnosis and clinical assessment of therapeutic efficacy. According to clinical research data hitherto, PET is expected to be an effective diagnostic tool in early and differential diagnosis of Alzheimer's disease. Since 2004, Medicare covers PET scans for the differential diagnosis of fronto-temporal dementia (FTD) and Alzheimer's disease (AD) under specific requirements; or, its use in a CMS approved practical clinical trial focused on the utility of PET in the diagnosis or treatment of dementing neurodegenerative diseases.