New CT scanners offer faster diagnoses

Hospitals are buying up new super-fast CT scanners, betting that these expensive machines will change dramatically how doctors diagnose chest pains and ultimately heart disease.

The machines, which snap as many as 4,000 images of the human heart in about 10 seconds, are seen as a way to spare many patients a cardiac catheterization, which requires a small incision and sedation and takes several hours. The new scanners are painless and can tell doctors in less than an hour whether a patient's heart arteries are clogged with plaque, putting the patient at risk of a heart attack.

But some physicians worry the machines will be overused, because research has yet to pinpoint the patients who would most benefit from the technology. The scanners are not risk-free -- patients are exposed to higher doses of radiation than for catheterizations or for X-rays, and must be injected with a dye than can cause allergic reactions.

Still, hospital executives and heart specialists are trying to get a jump on what they expect will be an exploding technology and are scanning growing numbers of cardiac patients. One of several manufacturers, GE Healthcare, said its LightSpeed VCT system is the most successful product in the unit's history; 800 have been sold since the product was launched a year ago.

''These scanners will have a major impact on patients coming into the ER," said Dr. Thomas Brady, director of cardiovascular imaging and intervention at Massachusetts General Hospital. ''Patients will have a definitive diagnosis earlier and get treatment earlier."

Mass. General, Brigham and Women's Hospital, Boston Medical Center, and Beth Israel Deaconess Medical Center are among the teaching hospitals that each have bought two, three, or four of these ''64-slice" CT scanners, which have 64 X-ray detectors that produce images of successive cross-sections, or slices, of the heart. They typically cost $1.5 million to $1.7 million and are the fastest CT scanners on the market -- fast enough to take clear three-dimensional pictures of a beating heart and the surrounding blood vessels. Community hospitals, including Mount Auburn in Cambridge, also are buying the machines, and cardiologists are beginning to install them in their offices. Next week, the Brigham will install the first 64-slice CT combined with a PET scanner, which allows doctors also to see how the heart is functioning.

A committee that advises Medicare on which tests and treatments to cover is scheduled to meet May 18 to evaluate coronary CT and other new cardiac imaging tests. Doctors expect Medicare to approve national coverage of cardiac CT scans this year, which probably will lead private insurers to adopt similar policies. For now, coverage varies by state, with most Massachusetts insurers covering the tests on a case-by-case basis.

Diagnosis of heart disease is a fast-changing field with ample room for improved screening and diagnostic techniques. About 500,000 Americans die each year from sudden cardiac death and for many of them death was the first sign of a problem. Current tests may miss signs of heart disease, especially in women, who are more likely than men to have problems in smaller vessels. And existing diagnostic techniques don't easily distinguish between the types of blockages that are likely to rupture and cause a heart attack and those that are stable.

''The big debate is not whether CT is an effective or good tool, but over which patients will be better served," said Dr. Marcelo Di Carli, co-director of cardiovascular imaging at Brigham and Women's.

At this point, most doctors agree that the new scanners should not be used to look for problems in healthy people. In addition to the radiation risk, CT scans may pick up tiny spots of plaque on artery walls that, in the absence of symptoms, are hard for doctors to interpret. They may not know whether the plaque poses a heart attack risk to the patient and requires treatment such as clot-busting medications or a stent to widen the vessel. Inevitably, many such patients probably would get treatment anyway, because it's hard for doctors to do nothing, especially given the fear of lawsuits.

''What I'm concerned about is using it as an overall screening device for healthy patients," said Dr. Samuel Shubrooks, a cardiologist at Beth Israel Deaconess and president of the Massachusetts chapter of the American College of Cardiology, which along with three other groups is developing guidelines that they plan to publish in June. ''That would certainly be a very expensive way to screen, and it may pick up things we don't know how to manage."

The other challenge is determining which of the patients who develop chest pain and other symptoms of heart disease will benefit from the 64-slice scans.

Most hospitals are developing guidelines for use of the machines in their emergency departments. The Brigham's approach is typical. The hospital is scanning patients in the radiology clinic who have had prior coronary bypass surgery or stents inserted and who have new symptoms that are not an emergency.

One such patient is Linda Kossin, 46, of Melrose, who had a CT scan on Thursday at the Brigham. She had experienced chest and back pain and tingling in her hands in 1997, which led to a cardiac catheterization and triple bypass surgery. When a routine stress test recently showed abnormalities, her primary care doctor wanted to change her medications and monitor her condition, she said. She was too worried to wait, and wanted to make sure her surgically repaired arteries still were open.

''It really threw me off, thinking something could be wrong," she said. ''I want to know what is going on."

Kossin said she was pleasantly surprised with the ease of the scan. The only sensation was a warm flush through her torso when a technician injected dye, which makes it easier to see narrowed arteries.

In the emergency room, the Brigham is poised to scan low-risk younger patients who have atypical chest pain that might not be related to heart disease. Doctors estimate that between 30 percent and 40 percent of diagnostic catheterizations find no blockage, and they are hoping that the scans might help some of these patients avoid this invasive test.

''The idea is to scan patients who are likely to be in this group, because it's very fast and you can get an answer very quickly," Di Carli said. ''You're really trying to exclude the possibility of acute coronary syndrome. The conventional way is to work them up with a stress test and some type of imaging. That can take three to four hours with the waiting time between steps. With the CT, we can cut down on ER crowding and cost."

Younger patients also are less likely to have calcium deposits in their arteries, which can make the scans difficult to read.

Patients who have crushing chest pain, who doctors strongly suspect are having a heart attack, still should have a catheterization because a CT scan is unlikely to provide new information and may waste time, Di Carli said. But a whole host of patients rest in the gray area.

''The technology has completely outpaced the data," Di Carli said. ''A lot of what we do is based on our best judgment. That is why insurance companies have been hesitant."

Teaching hospitals now are studying which patients will benefit from CT versus catheterization or a stress test, but it could take years to fully understand which test best predicts heart attacks in which patients. The cost implications could take years to play out.

Blue Cross and Blue Shield of Massachusetts, for example, pays an average negotiated rate of $1,000 for a diagnostic cardiac catheterization, but just $550 for a CT scan, which is used routinely to image other parts of the body and look for disease. At first glance, CT scans appear to save money. But will they?

Because CT scans are easier for patients to endure and faster, more patients are likely to have them than would undergo a catheterization. CT scans may pick up more signs of disease, leading to more and earlier interventional catheterization, where doctors insert stents to prop open arteries. These treatments could save the lives of many patients, but in other cases it may be uncertain whether the treatment is needed. Because doctors are looking at images, not the arteries themselves, studies are ongoing to see whether CT scans exaggerate blockages -- or understate them.

''This is not an all or nothing technology," said Dr. Valentin Fuster, cqdirector of Mount Sinai Heart in New York City. ''It is very helpful in certain people. But it doesn't work in a way that always gives you the answer."

Liz Kowalczyk can be reached at kowalczyk@globe.com.