A long-term study of 284 patients found PET scans early in the dementia process demonstrated a prognostic sensitivity of 93% and specificity of 76%. A negative PET scan indicated that pathologic progression of cognitive impairment was unlikely to occur during the mean three-year follow-up, according to the study published in the Nov. 7, 2001, Journal of the American Medical Association.

"Evidence strongly supports the value of FDG-PET as an alternate diagnostic approach for AD," Dr. Peter S. Conti told CMS's Medicare coverage advisory committee (MCAC) at a meeting in Baltimore.

The panel will consider several questions before giving its recommendation to CMS: * Can PET be used to determine patients' type of dementia, thus facilitating early treatment of AD and perhaps other dementia subtypes? * For patients with mild cognitive impairment, could PET be used to identify a group of patients with a high probability of AD so they could start early treatment? * Is the available evidence enough to justify PET's use in patients with a family history of AD so that they could start early treatment?

Representing the Society of Nuclear Medicine, Conti, an associate professor of radiology at the University of Southern California, said FDG-PET is more effective than a clinical exam for the differential diagnosis of various dementia and, therefore, will lead to more effective disease management. He added that home care for a person with AD costs about $47,000 per year and that 14 million baby boomers could develop AD by the middle of this century.

"Providing families and physicians with the means to better manage those with this disease would seem to be a more cost-effective approach to care. We believe this approach should include access to and reimbursement for PET scans," he said.

In 2000, the University of California, Los Angeles requested broader coverage of FDG-PET indications. On Dec. 15, 2001, CMS issued a decision memorandum approving the request for many oncological indications and heart disease, but it requested more evidence before granting coverage of neurological disorders.

"There's evidence that PET has the ability to diagnose Alzheimer's disease," Dr. Robert E. Henkin, acting chair of radiology at Loyola University, told Diagnostic Imaging. "If PET imaging can help us separate Alzheimer's disease from other forms of dementia, then it's useful. If it can help confirm a patient who has moderately advanced Alzheimer's disease, then it's useful."

-- By C.P. Kaiser

FDG-PET can detect Alzheimer's disease at its earliest expression (Nov. 2001)

Medicare changes encourage growth of outpatient PET (June 2001)

New indications give PET a lift after struggle over regulatory and reimbursement issues (Jan. 2000)

MR and PET vie in diagnosis of Alzheimer's disease (Nov. 2000)