Convert imaging turf battles into productive joint ventures

Since the introduction of cardiac catheterization in the 1940s, development and implementation of cardiovascular imaging techniques have been a collaborative effort among several specialties, particularly radiology and cardiology. Many pioneers in CV imaging have held joint appointments.

Because cardiologists have predominantly performed coronary angiography and cardiac echocardiography in recent years, many radiologists have had only minimal training in these areas. Most cardiologists, on the other hand, have not been trained in the physics and technology of MR, CT, and PET imaging. With the advent of clinically applicable advanced CV imaging such as cardiovascular MR (CMR) and CT (CCT) and wider dissemination of cardiac PET, patients will benefit from the combined expertise of cardiologists and radiologists.

Achieving a productive working relationship between these two specialties is generally not easy. In many institutions, radiologists and cardiologists compete over who is best qualified to read advanced cardiac imaging. At UCSD, we believe both groups bring essential expertise to this enterprise, and we have formed a joint venture to maximize benefit to the patient. While radiologists could certainly learn to read cardiac anatomy and pathology as well as cardiologists, and cardiologists could learn the complicated physics of MR imaging and the technology and radiation exposure associated with CT and PET, it is unlikely that all but a few will be fully conversant with both disciplines until a truly integrated training program is developed.

The authors have learned not only from each other but from our colleagues in the discipline in which we did not train. When we first worked together at Long Beach Memorial Medical Center, Dr. Bradley taught MR physics and image optimization to his fellows and Dr. Grover. As we performed and read cases together, Dr. Grover taught the fellows and Dr. Bradley how to optimize the study to answer the clinician's question and how to interpret cardiac anatomy, function, and physiology to help the clinician care for the patient.

Introducing new tests into practice patterns takes time, for multifactorial reasons. Clinicians need to see data that convince them the new tests will provide information as good as or better than the old tests. Hearing about the advantages of a new test from a colleague in their own field, rather than from someone who will derive economic benefit from new referrals, is likely to be more persuasive.

Even in academic institutions, economics plays a role. When Dr. Bradley moved to UCSD and realized that the institution did not have a CMR specialist or program, he met with Dr. Anthony DeMaria, the chief of cardiology, and proposed hiring Dr. Grover as codirector, with a cardiothoracic radiologist, of advanced cardiac imaging. Radiology and cardiology agreed to split Dr. Grover's billings, as all cases are read out jointly with both radiology and cardiology trainees in attendance. When Dr. Grover is in San Diego, we read from various cardiac imaging workstations. When she is out of town, we read and teach using the Internet and VitalConnect (Vital Images), which allows 4D cardiac imaging and uses an arrow that can be seen on both the local and remote monitor.

IMPACT OF 3T

CMR at 1.5T is fast becoming a clinical reality. How cardiologists and radiologists partner to provide the highest quality studies depends on local factors. With 3T CMR, however, radiologists, physicists, and cardiologists will have to work closely to optimize clinically relevant imaging.

We recently installed three 3T MR scanners at UCSD and are beginning to explore applications of 3T imaging for CMR. While it would seem logical that both temporal and spatial resolution could be improved at higher field strength, the physics have proven challenging. For example, the wavelength of a radiowave at 128 MHz (resonance frequency at 3T) is about the same dimension as an adult chest. The dielectric effect produces standing waves that result in signal variation and difficulties in refocusing phase in coherent bright blood techniques such as steady-state free precession pulse sequences (e.g., FIESTA and TrueFISP). T1 prolongation causes contrast changes at 3T, and sequences that are dependent on T1 must be modified. An example is delayed enhancement in which the myocardium is nulled based on its T1 value.

In this initial period of 3T cardiac imaging, people with expertise in MR physics and pulse sequences (usually physicists and radiologists) will likely play a larger role. Once the protocols and artifacts are worked out, people with knowledge of cardiovascular physiology and patient care will probably assume a larger role. The synergy of the partners in the joint venture may not lead to comparable involvement at all stages of new technology development and evolution.

CCT provides a good example of how collaboration improves test performance and interpretation. Radiologists can design protocols that optimize temporal and spatial resolution while minimizing radiation. Cardiologists can make decisions about and administer beta blockers to regularize and slow the heart rate. Cardiologists and radiologists can then interpret the cardiovascular and noncardiovascular findings and artifacts of the studies together.

ADDITION OF PET

When the UCSD Center for Molecular Imaging installed a PET scanner and cyclotron, our primary focus, like many other PET centers, was initially cancer detection. But myocardial stress perfusion imaging is an emerging area in which collaboration between radiologists and cardiologists is advantageous.

A myocardial perfusion study involves stress and rest scans. Our cyclotron can produce short-lived isotopes such as nitrogen-13 to make N-13 ammonia for myocardial perfusion imaging. Because N-13 is short-lived, it must be injected onsite.

Stress is achieved by an intravenous injection of the coronary vasodilator adenosine. Electrocardiograms (ECGs) are monitored before and during the stress study, and a crash cart is available. While a few cardiac radiologists are comfortable administering adenosine, interpreting the electrocardiographic response, and treating problems that may arise, most radiologists prefer that someone accustomed to these tasks perform them.

Our radiology-cardiology joint venture enables us to increase the types of studies that can be done in our PET facility, to our mutual benefit as well as that of patients.

The joint venture also provides cross- fertilization of ideas, leading to new areas of research that neither party might be able to persue individually. At UCSD, Dr. Graeme Bydder, known for his development of FLAIR and STIR, has been applying ultrashort TE (UTE) MR imaging to musculoskeletal, hepatic, and central nervous system structures and abnormalities with short T2s. Working with cardiologists like Dr. Grover, Dr. Bydder and his group hope to use UTE for imaging of calcification, which should allow them to differentiate stable, calcified plaque from noncalcified, and perhaps vulnerable, plaque.

Setting aside our turf battles and Manhattan Projects and working together fosters complementary expertise that can potentially maximize patient care. When we adopt this frame of mind and forget about who gets paid for what, collaboration becomes a powerful tool.

Dr. Bradley is a professor and chair of radiology, and Dr. Grover-McKay is director of advanced cardiovascular imaging, at the University of California, San Diego. Dr. Bradley has received grants/research support from GE Healthcare.