Part B Insider (Multispecialty) Coding Alert

But more expansion may be on the way

Medicare issued a draft of the long-awaited decision memo allowing coverage of PET scans for early dementia -- but the result was too narrow to be of use to most doctors.

In the decision memo (CAG-00088R), the Centers for Medicare & Medicaid Services said that it will cover 2-deoxy-2-fluro-D-glucose positron emission tomography, otherwise known as FDG-PET, for patients with a "recent diagnosis of dementia." But only in one circumstance:

You can use an FDG-PET to narrow down a new dementia patient's diagnosis if the patient meets diagnostic criteria for either Alzheimer's Disease or fronto-temporal dementia. You must have evaluated the patient for alternative causes of dementia and the cause of the symptoms must remain uncertain.

Also, the clinical course of the patient's dementia must be "aberrant" or unusual for Alzheimer's and you must suspect FTD as an alternative reason. A physician experienced with diagnosing dementia must have performed a clinical examination of the patient, without pinning down a cause. Documentation must include the results of the examination and lab tests, and the scan must happen in an accredited facility.

But CMS says it won't cover FDG-PET to diagnose dementia in other circumstances, except for under conditions of a clinical trial, where the aim is to monitor, evaluate and improve clinical outcomes.

The new decision memo "will probably limit the ability of physicians to be able to use" FDG-PET, complains Wayne McCormick, an internist and geriatrician who is associate professor of medicine at University of Washington in Seattle.

Even in patients who meet the narrow coverage criteria, most physicians won't feel confident enough to say that they've narrowed the diagnoses down to Alzheimer's and FTD and eliminated all other possibilities, warns McCormick. "In a way it's subconsciously inhibiting to physicians" to impose such a stringent requirement.

"Sophisticated consultants will be able to do that," including neurologists and geriatricians who encounter dementia a lot, says McCormick. But "the rank and file will not be able to do that confidently."

Note: The draft decision memo on FDG-PET is at www.cms.hhs.gov/mcd/viewdraftdecisionmemo.asp?id=104.