The first call Sheldon Goldberg got on his first day as president of the Alzheimer's Association was not from a patient or a doctor but from Michael D. Bromberg, chairman of the Capitol Health Group, a well-connected Washington lobbying firm.

"He said he had a problem," Goldberg recalled, "and the problem was the position of the Alzheimer's Association."

Bromberg represented an industry that stood to make millions if PET scans -- already used to help diagnose some cancers -- were to be reimbursed by Medicare as a test for Alzheimer's. Medicare officials had already said no, citing inadequate evidence that PET was useful in diagnosing the disease.

Independently, the association's experts had concluded the same.

Bromberg aimed to change Medicare's mind, but that would be tough without the association's support. If the nation's largest Alzheimer's advocacy group saw no value in PET -- short for positron emission tomography -- why should the government pay for it?

Last month, 21 months after Bromberg's call, Medicare announced that it will start paying for PET scans for some patients suspected of having the brain disease. How the agency came to that decision is a quintessential Washington tale of politics and persuasion -- and of how difficult it can be for a science-based agency to hew to evidence when it sits at the crossroads of medicine and money.

The Centers for Medicare and Medicaid Services (CMS), the agency overseeing Medicare, is bound by law to pay only for "necessary and reasonable" tests. But the PET industry did not conduct new studies or gather fresh evidence of its usefulness after being turned down for Alzheimer's coverage in 2003. Instead, PET proponents took a political path.

The first step, according to several people involved, was to persuade the Alzheimer's Association to soften its stance on PET. Then, they said, they played a card that had paid off for them before: a longstanding friendship between Michael Phelps, PET's inventor, and Sen. Ted Stevens (R-Alaska), chair of the appropriations committee that controls CMS's purse strings.

The Senate's senior Republican is famed for getting his way, often by refusing to bring spending bills to the floor until pet provisions are added. "It's never decided until we win," Stevens boasted last year.

Working with his chief health adviser, Elizabeth Connell, Stevens put that philosophy to work for Phelps by putting pressure on Medicare officials and on Health and Human Services Secretary Tommy G. Thompson.

"It's a simple fact that without Ted Stevens and Liz Connell, we would not enjoy the privileges that we have today with PET," said Phelps, who is a co-founder, board member and major shareholder in the nation's leading PET company.

"We ran into a lot of people . . . who were obstacles," Phelps said, speaking to scores of PET experts Sept. 8 during a conference focused on winning even more influence in Washington. "Guess what? They're all gone! That was Liz. So we all appreciate Liz."

Lagging Profits

Unlike magnetic resonance imaging (MRI), the widely used imaging method that creates fine-grained photos of the body's interior, PET does not reveal physical or anatomical structures. Rather, it shows places where the body's metabolic processes are out of balance. It does so by tracking radioactive chemicals injected into the blood.

A typical $2,000 PET scan can highlight, for example, spots in the body where greater-than-normal amounts of sugar are being consumed -- evidence that too much growth is going on, probably by a glucose-guzzling tumor.

PET and MRI were both invented in the early 1970s, but PET has lagged far behind in approved uses and profits. The 1,000 or so PET scanners operating in the United States today account for less than 5 percent of the more than 50 million diagnostic imaging procedures conducted annually.

Not least among PET's impediments was the Food and Drug Administration's discomfort over the chemicals, which can emit in one procedure the radiation in dozens of chest X-rays. It was not until 1998 -- after Stevens and Connell crafted legislation to speed FDA approval of those chemicals -- that Medicare agreed to cover PET for the first time, to spot lung tumors.

Since then about a dozen other cancers have been added to the list, as studies showed PET's value for finding them. But the industry has long had its eye on a bigger prize.

Alzheimer's disease already afflicts more than 4.5 million Americans -- a number that could grow to 14 million by 2050 -- and countless aging baby boomers will soon want to know if their memory problems are early signs of the disease.

No test short of an autopsy can establish with certainty that a person has Alzheimer's, though doctors can usually do so on the basis of symptoms. The challenge for PET was not only to show that it could diagnose Alzheimer's better, but also to prove that such an improvement made a difference for patients -- a difficult task, given the very modest benefits that come with today's Alzheimer's drugs.

After a study done for CMS said it made more sense to simply give the drugs to everyone thought to have Alzheimer's, CMS refused last year to cover PET for the disease.

PET's backers regrouped.

Leading the charge, as with previous efforts, was Phelps, a co-founder and board member of CTI Molecular Imaging of Knoxville, a major producer of PET scanners and the nation's leading supplier of PET chemicals. Phelps holds more than 2.7 million shares of CTI stock, currently valued at about $22 million, according to company records. He also holds academic appointments at the University of California, Los Angeles.

Broader reimbursement by Medicare -- and coverage by private insurers, which typically follows -- "is critical" to PET's growth, company documents state, noting that Alzheimer's is the industry's "next opportunity." CTI's revenue doubled to about $360 million in the two years after Medicare began covering PET for several cancers in 2001.

Phelps is a past president of the Academy of Molecular Imaging, a nonprofit that organized the Sept. 8 meeting and has paid Bromberg and another lobbyist more than $500,000 to work for expanded Medicare coverage. He is also a repeat donor to Stevens's campaigns, according to federal records. He has known Stevens for almost a quarter-century, and by his own accounting communicates with him and Connell almost daily.

"We drink together, we suffer together, we celebrate together, we fish together," Phelps said.

Muted Claim

To bring the Alzheimer's Association around, PET's supporters pulled back from their claim that PET could diagnose Alzheimer's, and focused instead on the narrower idea that PET could distinguish between early Alzheimer's and fronto-temporal dementia (FTD), a group of brain diseases that resemble Alzheimer's at first but progress differently.

Experts at the association and CMS said they were less than convinced that PET could even do that very well.

"I don't think the evidence is airtight by any means," said Marilyn Albert, a professor of neurology at Johns Hopkins University and chairman of the Alzheimer's Association's medical and scientific advisory council. The council took up the question after Goldberg got the December 2002 call from Bromberg.

Sean Tunis, who directs the CMS office that makes Medicare coverage decisions, called the evidence that PET could differentiate between Alzheimer's and FTD "modestly good."

"In the hands of skilled readers, looking at good quality scans, you can get some useful information," Tunis said. "That's a lot of caveats."

The association and CMS both feared that allowing coverage of PET for the narrow indication would open the door to much wider use of the technology for Alzheimer's -- especially in response to overreaching ads that have already begun to appear on television and in other media, according to Albert and others. But the association decided to give the technology a chance, agreeing to endorse the narrow use of PET -- with a long list of written reservations.

That placed the ball in CMS's court.

Phelps and his colleagues gave CMS the best evidence they could muster -- then placed their trust in Stevens, who evidently did not aim low.

"Secretary Tommy Thompson, in response to Senator Stevens's concerns, has become personally involved in deciding on this coverage," Connell told PET supporters at the meeting Sept. 8, a week before the decision was announced.

Bill Pierce, a spokesman for Thompson, declined to describe Stevens's influence except to say, "Nothing out of the ordinary went on here." Neither Stevens nor Phelps responded to phone calls and e-mails seeking comment.

Several current and former officials from CMS and its predecessor agency, known as HCFA, said in interviews that Stevens has often used his influence to help PET.

At least once he held up the agency's funding over a PET coverage proposal, according to two agency officials, one current and one former, both of whom spoke on the condition of anonymity. Others said he was willing and able to cut CMS programs favored by officials perceived as obstacles.

At the Sept. 8 meeting, after Phelps gave Stevens and Connell an award "for all they've done to help PET," Connell told her audience what "a painful process" it had been.

She expressed a "profound sense of disgust" for the Medicare Coverage Advisory Committee, the group of experts whose review of the evidence had resulted in CMS's initial rejection of Alzheimer's coverage in 2003, calling the group's evidence-based analyses "nonsensical exercises." And she railed against those who have sought to trim reimbursements for PET.

"Ted Stevens has had to become personally involved in making sure that CMS does not reduce payments for PET. . . . But Senator Stevens and I and Mike Phelps have persevered."

Later that day, Connell -- apparently unaware there was a reporter standing nearby -- gave a demonstration of her technique.

Herb B. Kuhn, director of the Center for Medicare Management at CMS, had just given a general talk to the PET advocates about how Medicare makes its coverage decisions and was about to leave the meeting room when Connell approached him.

"I want to let you know that Jennifer Young [acting assistant secretary for legislation at HHS] has been in touch from the Secretary's office. He's watching this very closely," she said, looking hard at Kuhn. "Just want to make sure you do the right thing."

Especially under pressure at CMS was Tunis, the medical officer responsible for making the final decision. Underwhelmed by the evidence but well aware of the forces at work, Tunis finally crafted a compromise. Medicare would cover PET for the narrow purpose of distinguishing between Alzheimer's and FTD -- with specific restrictions to try to ensure that the technology's use would not grow beyond those bounds. In return he got something important, Tunis said: an agreement by PET interests to collaborate with CMS and the National Institutes of Health in a major study that might finally show -- if it remains free of political interference -- just what PET can and cannot do for Alzheimer's patients.

Along those lines, Connell had reassuring words for her audience at the meeting. She said she and Stevens had already written legislative language specifying that the Agency for Healthcare Research and Quality -- the evidence-demanding agency that managed the study recommending against broad coverage for Alzheimer's -- "is not expected to be involved in this effort in any way."

That earned her a standing ovation.

Research editor Lucy Shackelford contributed to this report.

A patient undergoes imaging by a PET scanner. The procedure has recently been approved for coverage by Medicare in some cases as a test for Alzheimer's disease.A technician reads images of a patient's PET scan. A campaign, led in part by Michael Phelps, co-founder of CTI Molecular Imaging, a maker of PET scanners, recently led to its limited approval as a test for Alzheimer's disease.