Positron emission tomography (PET) is a non-invasive imaging procedure used for measuring the concentrations of positron-emitting radioisotopes within the tissue of living subjects. 2-[F18] fluoro-2-deoxy-D-glucose (FDG) is a radiopharmaceutical that is attracted to higher areas of metabolism. On December 15, 2001, CMS published a Decision Memorandum on a request for broad coverage (CAG-00065) of all oncological indications, heart disease, and neurological disorders. The December 15th decision memorandum stated that CMS had insufficient evidence to support coverage for the indication of Alzheimer's disease/dementia (AD).

On April 16, 2003 CMS released a Decision Memorandum stating that it would retain the previous noncoverage decision of PET for AD. The analysis concluded that the addition of an FDG-PET scan to the standard evaluation of AD does not result in improved patient outcomes. It was determined that the available evidence was adequate to conclude that an FDG-PET scan is not reasonable and necessary when used in the diagnosis and management of early dementia in elderly patients for whom the differential diagnosis includes one or more kinds of neurodegenerative disease.

CMS has received a new request from UCLA requesting a more restrictive coverage determination be made for the use of FDG PET to distinguish patients with AD from those with other causes of symptoms confounding the diagnosis of dementia or to assist with the diagnosis of early dementia in beneficiaries for whom the differential diagnosis includes one or more kinds of neurodegenerative disease, in cases where specific criteria have been met.