State of cardiac imaging represents ‘defining moment’ for radiology

Radiologists must embrace cardiac imaging, especially coronary CT angiography, but many are hesitant if not reluctant to do so, according to Dr. Kerry M. Link, a professor of radiology, cardiology, regenerative medicine, and biomedical engineering at Wake Forest University Health Science Center.

Advances in cardiac imaging will have a profound and long-lasting effect on medicine, health economics, and especially the field of radiology, Link said, during the annual oration in diagnostic radiology, "Cardiac imaging: A second chance," on Tuesday.

"Regardless of whether or not radiology is successful at staking a more significant claim in cardiac imaging, we will mark this time as a defining moment and as the beginning of significant changes in radiology's role in medical imaging," Link said.

Despite widespread coverage of cardiac CT in medical journals as well as the mainstream media, Link noted lack of enthusiasm for cardiac CT among colleagues, summarized by remarks such as:

• Cardiac imaging is considered the purview of cardiology. There is no sense even in trying to break the stranglehold.

• Given the current manpower shortage, diverting time and effort to cardiac imaging is not being economically viable, especially since heart disease and the technologies used to image the heart are complicated and beyond our current knowledge base.

• Will cardiac CT make a real difference or is it simply a new technology looking for an application?

• It's unclear how the new technology can be assessed within the context of coronary heart disease itself, not to mention heart disease in general.

Link called the last statement the most disturbing.

Radiologists also need to know what is at stake regarding cardiac imaging. Collating information from the latest death statistics, he reported that the top five causes of death are heart disease, cancer, stroke, chronic lung disease, and accidental death. Cardiovascular disease is the underlying cause of death for nearly 1 million Americans and the contributing cause of death in 1.4 million Americans.

Within heart disease, coronary heart disease is the leading cause of death, responsible for nearly 500,000 deaths, with an additional 225,000 deaths due to hypertension and other heart diseases. To put this into perspective, stroke is responsible for 157,000 deaths and peripheral vascular disease for 36,000 deaths. Heart disease is the most common disease in the U.S. and it is the single largest expense to the healthcare system, Link said.

It's not feasible to work up every patient with acute chest pain in the catheterization lab. Many patients fall into a pretest probability of intermediate risk, which accounts for the large numbers of echocardiology and nuclear cardiology studies performed in the U.S., he said. But there are always equivocal cases with these two modalities. Additionally, diagnostic cardiac catheterization only measures the lumen, which can miss vulnerable plaque, a major focus of today's coronary disease research.

Significant disease goes undetected all the time with diagnostic angiography, as well as perfusion and wall motion imaging, he said. This is due to compensatory extension of the vessel wall, which delays the development of stenoses until the end of the atherosclerotic process.

"It is the detection of the vulnerable plaque that should be the holy grail of coronary imaging," he said, adding that CT surpasses diagnostic angiography for this purpose because it visualizes the vessel wall.

Link detailed advances in postprocessing techniques that propel CT beyond what is possible with catheter angiography.

It's not enough, however, for radiologists to simply interpret the exam that is in front of them. They must become information integrators, which is possible by accessing the patient's electronic records. The cardiac imager needs to understand all tests, review all studies, and be familiar with echo and nuclear cardiology.

"It doesn't matter how good you are at interpreting a study. Failure to integrate all information just reinforces the notion that cardiologists are better at reading cardiac imaging studies," Link said.

He noted that many echo and nuclear cardiology studies are not accessible through hospital-wide PACS and are not available for general review by noncardiologists. This should not be allowed and it has tremendous symbolic meaning, he said.

The good news is that radiologists are well versed in CT, giving them an advantage they didn't have with echo and nuclear cardiology. Additionally, cardiac CTA applications will have a significant effect on a prevalent disease and therefore should justify the redistribution of resources, he said.

Radiology is in a unique position to provide the most information without billing multiple interpreters - a clear value-added service, he said. However, it depends on radiologists to embrace coronary CTA and cardiac CT.