Using MR technology to examine a patient’s heart is moving slowly out of the ivory towers of research hospitals and into the real world. Although MR has been used in cardiac research applications for about a decade, upgrades to MR machines and their software have pushed cardiac MR into a more mainstream patient population in the past 2 to 3 years.

Last year, a landmark National Institutes of Health (NIH) report published in Circu-lation: Journal of the American Heart Association showed that MR can identify patients with coronary artery disease among those presenting with chest pain and low/ intermediate coronary risk more accurately than traditional methods, such as EKGs, blood enzyme tests, and the TIMI risk score (thrombolysis in myocardial infarction). But most emergency departments (EDs) do not have access to MR equipment and services to make a timely difference.

A Duke University research study found that MR is able to detect areas of abnormally contracting heart muscle that will respond favorably to revascularization; however, those areas don’t show up using other imaging technologies. In the past, cardiologists generally had presumed this kind of tissue lost.

Both of these studies hint at possible future applications of cardiac MR. Today, the technology is expanding the practice of cardiologists and the radiologists with whom they work in other ways: assessing ventricular volume for valvular heart disease when echocardiograms can’t give a complete enough picture; oncology applications; pre- and postoperatively assessing for congenital heart disease patients; and assessing myocardial viability prior to bypass surgery.

According to Dr Gerald Grubbs, director of radiology for Axcess Diagnostics (Venice, Fla), cardiac electrophysiologists also make use of heart MR images. These physicians, who actually stop and restart patients’ hearts to examine irregular heartbeats, need the most accurate imaging techniques available in order to gather the most information up front, before undertaking these cutting-edge procedures.

Cardiac MR scans are still on the cutting edge of medicine, yet the day of the routine cardiac MRI could be coming, according to Robert Balaban, PhD, scientific director of the federal National Heart, Lung, and Blood Institute’s Laboratory Research Program (Bethesda, Md) and co-author of the NIH report.

Dr Warren Manning is a Harvard medical professor, section chief of noninvasive cardiac imaging at Boston’s Beth Israel Deaconess Medical Center, and president of the Society for Cardiovascular Magnetic Resonance (SCMR of Mount Royal, NJ). “The vast majority of major medical centers in the United States have, or are in the process of developing, a cardiac MR program,” he says. The question remains, though, of what to do with cardiac MR once those programs are in place.

Manning says that MRIs provide data that is much more comprehensive than the information provided by other noninvasive tests. “Clinicians actually are not accustomed to getting such accurate information; they need to learn how to integrate that into their clinical practice,” he says. “As a research group, we need to find out how more accurate data is going to impact patient care. We believe better information will help us take care of patients better—but in all honestly, we have to prove it.”

Stacking Up
In the cardiac diagnostic arena, MR compares well to other noninvasive techniques, such as echocardiography or nuclear cardiology, the latter of which includes PET, MUGA, and SPECT scans.

Compared to MRIs, Manning calls echocardiograms “technically deficient.” Grubbs agrees, adding that MR can provide 10 times the resolution of an echocardiogram. In fact, with older patients who have chronic lung disease, an MRI can provide a clear picture of the heart where an optimal echocardiogram can’t even be made.

“For many individuals, the technical quality of an echocardiogram is not as high as we would like. We often make clinical decisions on the information we have, but we don’t always have a full assessment of the heart,” Manning says. “MR is a volumetric technique that gives us a comprehensive assessment of the heart: its function, mass, viability, and, at some centers, coronary anatomy as well.”

He says that MR offers “far superior” spatial resolution and a more comprehensive assessment than the nuclear processes, which involve administering a mildly radioactive drug and then taking a picture of the distribution of the drug in the patient with a gamma camera.

Manning sees potential for the diagnostic applications of “delayed enhancement MR,” an angiography technique that involves injecting patients with a substance, such as gadolinium, to enhance heart scans. Research studies—like one conducted by Nanaka Kawada, MD, et al, at Mie University in Japan—show that delayed enhancement MR can give a better picture than SPECT scans during stress tests when evaluating angina in patients.

Grubbs estimates that in some cases, MR offers 100 times the resolution of traditional nuclear techniques, showing the heart in “exquisite detail” and without the blind spots sometimes found in images that are created using other technologies.

“With echocardiograms, you have to use these complex geometric assumptions and mathematical formulas to figure out how the left heart and right heart are working,” Grubbs says. “But with MR, we get exact models of what’s going on. We get dead-on accurate measurements.”

Still, despite MR’s advantages, Grubbs postulates that the technology probably won’t eliminate the need for echocardiograms, even if every hospital has access to a scanner. Echocardiogram equipment has the portability and the ability to give an instant—albeit less clear—picture of what’s going on in a patient’s heart. That reason alone will keep it in use for considerable years to come.

Educational Challenges, Rich Rewards for Technologists

Creating a cardiac MR takes time to learn. Although some training programs exist, many technologists currently cut their teeth with apprenticeships under cardiologists or radiologists.

Some technologists come from the heart side of the profession, learning MR after working with ultrasound equipment and echocardiograms. Others come from the MR side, learning how a heart scan differs from scanning other areas of the body that they might have scanned before.

The biggest challenge is augmenting education: MR technologists who want to learn cardiac MR must learn heart physiology; echocardiography techs who want to learn cardiac MR must study the art of making scans. Once a tech completes the requisite course work, he most likely will undergo practical training under the eye of a cardiologist or radiologist to become competent in the field.

Learning the ropes will probably become easier as MR technology improves, says Robert Balaban, PhD, of the federal National Heart, Lung, and Blood Institute’s Laboratory Research Program. “Becoming a technologist isn’t as daunting a task as it was 5 years ago,” he says. “We hope that as the field matures, it will become less of an impediment. We’re engaging manufacturers very intensely to come up with a much more user-friendly and knowledgeable interface, rather than the static interface that is common now.”

Although both groups might come to the table with discrete experience, one thing’s the same when they get there: Tech-nologists who can perform cardiac MR are in demand.

“[MR] techs have to learn a totally new set of anatomy, it’s a huge learning curve,” says Dr Gerald Grubbs of Axcess Diagnos-tics, adding that his apprentices take 6 to 12 months to learn the heart, then learn how to get the imaging planes in different people.

“Once [the techs are] trained, they’re worth their weight in gold and can write their own meal tickets. Folks who used to make [upward of] $70,000 who have this training are now saying, ‘Don’t even talk to me unless you can pay me $125,000.’ ”

More information for technologists—including an educational directory and credentialing guidelines—can be found at the Society for Cardiovascular Magnetic Resonance Web site (www.scmr.org). Membership is required for some of the site’s content, but prospective technologists can read quite a lot of information on cardiac MR education and technique for free.

One section of the site that might be of particular interest shows protocols in PDF format. Uploaded by practicing specialists, they show step-by-step cardiac MRI procedures.

—DF

ED Use: Good Theory, Difficult Practice
Is the ED the next frontier for MR? Maybe. For 80% of the patients who arrive in emergency rooms with chest pains, it’s not immediately obvious whether or not they had or are having a heart attack.

The NIH study showed that MR could detect many heart attacks faster than other techniques and in enough time to administer treatment to restore blood flow, such as clot-busting drugs, angioplasty, or coronary artery bypass surgery. Clinical guidelines call for these treatments to begin within an hour from the start of a heart attack; the MRIs in the NIH study took an average of 38 minutes.

Despite the concrete evidence for life-saving applications of the technology for heart attack patients, the size and cost of MR scanners could be a barrier to widespread adoption for this use.

“When patients come into the emergency room with chest pains, time is of the essence,” Manning says. “Never say never, but I think it will be a long time before we have the luxury of having an MR scanner in the ED specifically available 24 hours a day just for emergent chest pain patients.”

Balaban concurs—it might not be feasible for every ED to have its own scanner dedicated to cardiac MR. But he says he sees a likely future where an emergency room might have access to equipment for both potential heart attack and stroke patients, two areas in which a sharp MR scan can help determine treatment options in time to make a major difference in outcomes.

“The bottom line is the business plan,” he says. “Can you make one where an MR scan in an emergency room has enough value so that an institution can afford [it]? That’s a good point.” To that end, NIH is conducting further research.

Radiologists or Cardiologists?
As the medical establishment parses the growing body of knowledge about cardiac MR—including a new scanning procedure that can show a beating heart—and ascertains applications for the technology, radiologists and cardiologists are sorting out who performs which heart studies.

In the small-but-expanding world of cardiac MR, no one holds all the cards. In some cases, radiologists make and read the scans; in others, cardiologists do. Sometimes, they work together. Balaban sees the trend of mixed specialists continuing into the future, with the size of the facility dictating which professional handles the cardiac MR.

“I see a blend occurring right now,” he says. “Cardiologists are a little unique in that they have a strong background in imaging ultrasound and catheterization, so they are more comfortable with an imaging modality than most other areas of medicine. I think it will depend on the particular academic or hospital situation.”

Both radiologists and cardiologists—along with technologists and nonphysician scientists—comprise the membership of SCMR, an 8-year-old association dedicated to the international advancement of cardiac MR and to the education of all professionals in the field. The group’s membership is closing in on 1,000; cardiologists currently outnumber radiologists by about 2:1, with technologists and scientists accounting for about 10% of SCMR members.

Both Balaban and Manning see a mixture of cardiologists and radiologists performing cardiac MR in the future. The breakdown will be based on the number of cardiac patients who come through a facility. For lower-traffic locales, chances are it will make financial sense for a radiology department to handle cardiac patients; large research facilities might feature more cardiologists; and in between, there will be some of both—as well as the two working together.

“All of these models are working at various institutions around the country,” Manning says. “But if [the use of cardiac MR] expands greatly, there will be increasing pressure for cardiologists to go out on their own.”

Balaban—who is neither a cardiologist nor a radiologist, but a physiologist—looks on the debate with interest. Both professions want to claim to be the best at cardiac MR in order to corner the future market and its potentially lucrative billings.

“Both sides have different arguments with regards to who can best interpret that data,” he says. “Cardiologists understand cardiac function data; radiologists have a better understanding of the technology since they’re trained extensively in that, and [they] also see other aspects of the chest in that image.”

Because of these factors, Balaban thinks it would be a mistake for cardiac MR to become the exclusive purview of one discipline or the other, and he says that continuing collaborative efforts will ultimately benefit the patient population.

Grubbs says that it probably will come down to economics—as he thinks that eventually, a good share of cardiac MR will be collaborative, with cardiologists reading the MRIs that radiologists take. For this reason, it’s important that doctors on both sides of the fence remain collegial.

He who owns the magnets gets the biggest piece of the pie, Grubbs says, and in the end, it’s likely that only the busiest cardiologists will see enough patients who need MRIs to justify the cost of the scanners. Radiologists, on the other hand, use MR technology for so many applications that heart scans will comprise only a small part of their practices.

Regardless of the business model that makes cardiac MRI the ken of cardiologists, radiologists, or some mixture of the two, reimbursement issues remain. Insurers will have to address reimbursement, which could determine the technique’s widespread adoption.

The bottom line isn’t whether a radiologist or cardiologist does the study, Balaban says; instead, it’s which model suits each facility to yield the best patient outcomes.

Bright Future
As cardiac MR expands from the research realm into the diagnostic arena, Balaban predicts that its biggest impact in the short term will be in the evaluation of heart disease and heart failure.

In the long term, there might be uses for MR in screening for heart disease if the technology’s costs could be reduced to make it feasible. Another promising use for cardiac MR down the road involves surgery as well; it could be the “eyes” of heart surgeons as they perform minimally invasive procedures with robotic tools. MR technology could work because of its ability to rapidly provide 3-D data.

“MR really has the best information suite to give the best diagnostic information,” Balaban says. “We have some business model problems, and we have reimbursement issues that are in the way—and they are significant. But I think the information content and the data you’re able to get is going to have a huge impact.”

Don Fluckinger is a contributing writer for Medical Imaging.