Specialists discover common ground in cardiovascular CT

The extraordinary capabilities of cardiac CT are drawing increased attention from cardiologists, who long ago conquered angiography, echocardiography, and cardiac nuclear medicine. That interest concerns radiologists, who worry about the potential for self-referral, inappropriate utilization, and lost turf.

In some cases the technology has heated relations between the two specialties, but a number of groups around the country are finding it more beneficial, for their practice and their patients, to work together rather than against each other.

Such collaborations offer one solution to what has become a raging national debate. At the RSNA meeting in November, concerns over self-referral and turf sparked calls for radiologists to take a leadership role in cardiac imaging. These sentiments are fueled in part by studies documenting cardiologists' increasing use of imaging studies. Dr. David Levin, former chair of radiology at Thomas Jefferson University, presented research at the meeting showing that radiologists' overall share of the cardiovascular imaging market declined between 1993 and 2002. During the same period, cardiologists' share of the market rose substantially.

Average relative value units in cardiovascular imaging increased more than twice as rapidly among cardiologists as among radiologists. While the study findings do not definitively point to self-referral as the cause of the increase, there is little doubt that is the case, Levin said.

During the same week those findings were reported, the American College of Cardiology and 17 other professional medical groups lambasted radiologists for protectionist policies that threaten to limit patient access to imaging.

"Dr. Levin is not telling the whole story," began a press release distributed by Physicians for Patient-Centered Imaging at the RSNA meeting.

Given this fractious climate, it would seem impossible that the two groups could ever get along. But collaborations between cardiologists and radiologists are emerging in several hospitals and clinics. Such ventures are based partly on the recognition that both specialties bring expertise to the cardiac imaging suite, but they also take into account the politics of medical practice.

At Cabrini Medical Center in New York City, a newly integrated cardiovascular imaging department is headed by a cardiologist but relies heavily on radiologist expertise in interpreting CT and MR cardiac scans.

Since creating the combined division eight months ago, the 400-bed community hospital has already seen increases in cardiac nuclear medicine volumes and cardiovascular CT, said Sean Healy, vice president of ancillary services.

"We've created a contractual, organizational structure where radiologists and cardiologists have to play well together," he said.

At Edward Heart Hospital in Naperville, IL, interventional radiologists and cardiologists simply find it easier to work together than apart, according to Dr. Manu Sehgal, a radiologist with Midwest Heart Specialists, a cardiovascular group that works with three Chicago-area hospitals in addition to Edward Heart. Cardiologists take the lead role in screening patients. Where appropriate, they refer them to interventionalists for peripheral vascular assessments and interventions (see "Radiologists, cardiologists cooperate in heart hospital," Diagnostic Imaging, March 2004, p. 55).

The Florida Institute for Advanced Diagnostic Imaging (FIFADI) in Port Richey has a cooperative partnership founded on coronary CT angiography. While cardiologists control the patients, radiologists control the scanners. There has to be a bridge for collaboration, said Dr. Steven M. Strobbe, executive physician and CEO. That bridge, for now, seems to be coronary CTA.

Here's how it works in a typical patient: A 61-year-old man with a history of peripheral vascular disease presents to his cardiologist with vague chest discomfort. He also has had a superficial femoral artery stent placement. Two months earlier, a thallium stress test was negative. Believing a cardiac catheterization might also be negative, the cardiologist refers the patient to FIFADI for coronary CTA. The multislice study reveals significant triple-vessel disease.

Such cases are not unusual, but the working relationship between institute cardiologists and radiologists is, Strobbe said. That's not to say that turf issues never arise.

"Of course there has to be a turf concern," said Dr. Robert Kudelko, a radiologist for FIFADI and chair of medical imaging at Suncoast Hospital in Largo. "But the philosophy here is to let the individual with the most expertise in the portion of the body interpret the study."

The institute recently began treating atrial fibrillation with ablation therapy. CTA is the presurgical tool of choice for this procedure, providing an anatomic road map to the electrophysiological cardiologist. CTA offers the ability to concurrently view normal and atypical coronary artery anatomy, providing the EP cardiologist with clearly de-fined landmarks, Strobbe said.

FIFADI consists of three facilities, one of them housing both a 16-slice CT scanner and a 1.5T cardiovascular MR device. A 64-slice CT and 3T MR are on order.

Evidence suggests that an MR perfusion stress test is a better study for ischemia than stress thallium, Strobbe said. But he has yet to create a means for radiologists and cardiologists to work together on this.

COLLABORATIVE IMPERATIVE

Similar models are at work in South Carolina and New York City. A cardiology group based in Columbia, SC, contracts with radiologists to read coronary CTA scans, a service it has performed since 2002. The cardiologists own the CT devices, and the radiologists provide exclusive reading services.

In New York City, Imaging Heart operates three centers and blends the patient management skills of cardiologists with the image interpretation acumen of radiologists.

"We work closely with cardiologists so that they can be involved in the system," said Dr. Stephen Koch, medical director of Imaging Heart. "A lot of radiology groups won't work with cardiologists. I think it's imperative."

Imaging Heart specializes in coronary CTA using 16-slice CT, al-though Koch is eagerly awaiting installation of the group's first 64-slice scanner. Advances in CT allow scans of the entire heart to be performed in 10 to 15 seconds. Radiologists can evaluate cardiac function and coronary artery plaque while assessing cardiac structure for other diseases.

That latter assessment is critical, Koch said, and it is the reason radiologists are key to the image interpretation process. CTA can help determine whether a patient's symptoms are truly cardiac in nature or the result of some other etiology: pulmonary embolism, aneurysm, aortic dissection, or even atypical pneumonia. But differentiating among the various abnormalities takes an eye trained in cross-sectional imaging.

"Cardiologists only look at the aorta and the heart," Koch said. "But what about the lung cancer that is sitting down in the lower lobe of the chest that they don't see, or the renal cell carcinoma, or the lymph nodes that are enlarged because the patient has lymphoma? At some point, they're going to miss some sort of pathology that will be detrimental to the patient, and they will end up with a huge medicolegal issue on their hands."

Koch works with cardiology groups to educate them not only about cardiac CT but also about the benefits that radiologists offer.

"We do all the heavy lifting-the 3D, the volume rendering, the MIP images," he said. "We do the radiology, and they can do the vascular applications. The fees we charge for this include my professional read, the postprocessing, and costs related to our nursing staff."

NONCARDIAC EXPERTISE

The importance of cooperation between cardiologists and radiologists received a scientific boost in November, when a study presented at the American Heart Association meeting in New Orleans documented the prevalence of significant noncardiac findings in patients with symptoms assumed to be of coronary origin.

The study involved 75 patients with chest pain or known coronary artery disease who underwent coronary CTA at Johns Hopkins Bayview Medical Center. Noncoronary abnormalities were identified in 36 of the patients. Of these, 12 patients, or 16%, had major noncardiac findings, said Dr. Irfan Shafique, a radiology resident.

The major abnormalities included two pulmonary embolisms, two lung masses, three cases of bulky lymphadenopathy, and three large hiatal hernias. Additional, minor noncardiac findings in the remaining 25 patients included a small hiatal hernia, esophageal wall thickening, liver cysts, atelectasis, and mild lymphadenopathy.

The study findings underscore the need for collaboration between cardiologists and radiologists to ensure optimal evaluation of CTA, Shafique said at the AHA meeting.

"It's important that radiologists review the entire scan, as a significant percentage of patients referred for coronary evaluation had noncardiac findings which could either explain the symptoms or warrant further investigation," he said.

Both Koch and Kudelko can contribute anecdotal evidence of noncardiac findings on CTA, which only radiologists are trained to find. In the first 100 coronary CTA cases performed at FIFADI, radiologists found five asymptomatic chest malignancies. Chest and arm pain is not always caused by cardiac pathology, Kudelko said. It can come from a variety of sources, including hiatal hernia and gallstones.

"It's my responsibility as a radiologist to discern these noncardiac sources of chest pain and to find the silent malignancies when they are potentially more curable, at 1 to 1.5 cm in size," he said.

At Johns Hopkins School of Medicine, the roles of cardiologists and radiologists are defined by their clinical strengths. Working collaboratively is a necessity with CTA, said Dr. Edward Shapiro, a professor of medicine.

"This technique provides us with an opportunity for cardiologists and radiologists to work together," he said. "That is crucial for its eventual success. Because a wide range of therapeutic decisions are based on the details of the coronary anatomy, which until now could only be detected by catheterization, coronary angiographic interpretation is best done by cardiologists at present. Radiologists are new to that."

At the same time, Shapiro said, noncardiac findings that commonly reveal themselves on CT scans require the involvement of radiologists.

EDUCATION NEEDED

The cornerstone of collaboration is education. In order for radiologists to work in partnership with cardiologists in the heart, they must pair their knowledge of cross-sectional cardiac anatomy with an understanding of cardiac disease.

A host of organizations, from the RSNA to the North American Society for Cardiac Imaging (NASCI), offer specialized education and training in cardiovascular imaging. Several vendors also offer masters courses on the topic.

"Radiologists are as prepared as cardiologists (to perform) CT studies of coronary calcium and coronary angiograms," said Dr. Melvin Clouse, vice chair of radiology at Beth Israel Deaconess Medical Center in Boston. "Radiologists must now learn about Framingham risk scores and national cholesterol protection guidelines. We need to apply what we've learned into practice."

NASCI offers good opportunities for radiologists and cardiologists to learn more about cardiovascular CT capabilities, said Dr. William Stanford, a professor of radiology at the University of Iowa and a NASCI board member. Attendance at the organization's annual meeting has increased substantially in recent years, with a large number of cardiologists participating.

"The meeting offers a good overview of all the imaging modalities and the pros and cons of each," he said. "If a person is sitting on the fence and not sure of the methodology, they can get some answers at NASCI."

Beyond understanding cardiac disease, radiologists must also master 3D imaging in order to excel at cardiovascular CT. Extending the power of 3D through training and education is a need that continues to go unmet, according to Dr. Geoffrey Rubin, chief of cardiovascular imaging at Stanford University.

"The analogy I like to use is that of a driver's education program," Rubin said during a plenary session at the RSNA meeting focused on 3D imaging. "Interactive and intuitive modules are needed so that users can simply focus on driving and not on how to operate the vehicle."