The agency also said it would incorporate the test in the “coverage with evidence development” (CED) program, which grants conditional reimbursement for what it considers promising new medical technologies while tracking the technology’s impact on health outcomes.

Eli Lilly, the drug company that manufactures Amyvid, the first PET tracer to be approved by the Food and Drug Administration, had asked for Medicare to pay for the beta-amyloid imaging class without the restrictions that come with the CED program.

“Our steadfast belief (is) that beta amyloid imaging should be a covered benefit for these Medicare beneficiaries without any restrictions such as coverage with evidence development,” Gilroy said in an interview this week.

In a July 3 statement, the company questioned the CMS’ draft decision. The CMS will not release its final decision until October.

“CMS appears to be challenging the value of an adjunctive tool that can assist physicians in making a more informed diagnosis for patients with cognitive impairment,” Dr. Daniel Skovronsky, president and CEO of Avid Radiopharmaceuticals, the Lilly subsidiary that developed Amyvid, said in the statement. “Restricting coverage could hinder a timely and accurate diagnosis, which is in conflict with the advice of Alzheimer’s disease experts and with the administration’s National Alzheimer’s Project Act. In addition, it may stifle future innovation aimed at improving diagnosis.”

However, a CMS panel in January questioned whether there is adequate evidence that brain beta-amyloid imaging will affect health outcomes for patients reporting early signs of cognitive dysfunction. And, some physicians say that while they support coverage of the test, there are concerns about the degree to which it will be used and by what providers.

“While I see great potential in all of this, the potential hinges on the test being used in the right context, in terms of the right patient and by experts who otherwise know the factors that can influence the result one way or another,” Dr. Norman Relkin, director of the memory disorders program in the department of neurology at Weill Cornell Medical College in New York, said in an interview this week.

An estimated 5 million Americans have Alzheimer’s disease and the number is expected to reach 7 million by 2025.

The diagnosis of a patient demonstrating signs of Alzheimer’s disease usually begins with an extensive routine evaluation before a physician will order an MRI or a CT scan. The combination of a structural brain image and the evaluation are often enough for many patients to receive a diagnosis. However, about one in five patients present with atypical symptoms or unusual types of progression, Relkin said.

“There are people for whom those tests are not definitive and for which the amyloid imaging can potentially tell us whether we’re dealing with Alzheimer’s or another form of dementia,” he noted.

In these cases, the additional information provided by amyloid imaging can aid physicians who are evaluating a patient with a short duration of symptoms or someone with past cognitive or behavioral problems that make conventional diagnostic techniques less accurate. The use of fluorodeoxy-D-glucose, also called FDG, is another tool that is often used.

“The potential to improve early diagnosis by tests like this is there,” Relkin said. “But it’s challenging, and it’s challenging for a number for reasons, because of the false positives and the false negatives and because of the impact of other factors like genetics.”

And, unlike many other medical tests, the test does not provide a ‘yes-or-no’ diagnosis. Physicians have discovered that some patients in their 80s and 90s develop amyloid deposits, but do not develop Alzheimer’s disease. In other cases, some patients whose symptoms align with those of Alzheimer’s disease do not show amyloid in their scans.

“If you attribute too much to the findings, they can be misleading. And likewise, if you use the test in the wrong context, it can be misleading as well,” Relkin said.

The Alzheimer’s Association worked with the Society of Nuclear Medicine and Molecular Imaging to develop appropriateness criteria for the use of amyloid imaging. The association said positive tests can mean patients can have earlier access to treatments and support services ranging from building a care team to financial planning.

“We feel it’s useful in an arsenal,” said Dean Hartley, director of science initiatives at the Alzheimer’s Association.

The FDA approved Lilly’s Amyvid imaging agent in April 2012. GE has developed its own PET amyloid imaging tracer, and another drug developed by Bayer and now owned by Piramal Healthcare is also in development.

As part of its FDA approval, Lilly is required to train healthcare professionals who interpret the tests and said it has trained more than 1,000 providers. However, some physicians have said they would support restrictions on the providers who order and read the test.

“It is a value when it’s used correctly,” Relkin said. “What I don’t support, however, is more or less carte blanche to use the test indiscriminately because I think it will add a burden to the healthcare costs that we have and it will have some negative outcomes.”