Demands of cardiac CTA defy oversimplification

September 1, 2006

Giving radiologists only noncardiac portion of exams ignores value that they bring to CT.

The reason the American College of Cardiology has higher educational standards for cardiac CT angiography than the American College of Radiology is that it needs them. The ACC is dealing with physicians who have no prior knowledge of CT, no training in radiation physics, no experience reading CT images of any type, and no training in imaging atherosclerosis on CT, which is separate and distinct from any other x-ray, nuclear medicine, or echo exam.

The problem I repeatedly see is the lack of CT knowledge on the part of cardiologist instructors. I have taught a significant number of radiologists who have returned from cardiology-based visiting fellowships with a total inability to produce a complete coronary CTA exam.

Dr. Newton feels this part of the exam is so easy that perhaps we should have scanners in Wal-Mart run by junior high school students and radiology technologists. The physician can then read these images later. Dr. Newton greatly oversimplifies the complexity of CT imaging and perhaps suggests that any "pseudoradiologist" can do it.

The saying, "we only recognize what we know" is very appropriate here. A little knowledge makes everything seem so easy-too easy-and this is sometimes very dangerous.

The image quality of coronary CTA has improved with 64-slice CT compared with that of 16-slice CT. When the patient's scan parameters are properly determined, the images are breathtaking. The questions really are: Who is best trained to determine the scan parameters and what qualifications are needed to teach other physicians how to scan patients and maximize image quality for each patient?

Radiologists complete four years of residency and, frequently, more years in fellowships to learn the nuances of medical imaging, especially CT. Radiologists are the experts in imaging atherosclerosis in every other organ of the body using any imaging modality including CT. To state that radiologists should be limited to reading the noncardiac portion of coronary CT exams and leave the coronary arteries to cardiologists ignores the decades of proven value radiologists have brought to CT imaging.

The easiest thing to read is a black line on a piece of paper, i.e., an electrocardiogram. But who would you rather have read your ECG: a cardiologist with years of training who has read thousands of these exams or a radiologist who has trained a few months reading ECGs? The answer is obvious. The same standard should apply to your coronary CTA.

For decades, if you needed a stress test or a cardiac catheterization, you absolutely needed a cardiologist. But now, the mere specter of an exam with superior diagnostic ability that can be created and read by any other physician besides a cardiologist is very threatening to the cardiology community. It also is very threatening to the radiology community to see what had been their exclusive turf being invaded by another specialty. Life changes for everyone.

I agree with Dr. Newton that the manufacturers of CT equipment are furiously driving the technical advances that make coronary CTA possible. But why are they doing this?

Would they be doing this if consumers of this technology-patients and their ordering physicians-had no use for the exams made possible by said technology? Coronary CTA is valuable because conventional workup of coronary disease, including cholesterol level and C-reactive protein measurements, fails. In my cardiovascular CTA practice, only half of the patients I see with moderate or severe plaque are on statin therapy. The rest, who should be on statin therapy, were missed by conventional disease risk factors.

It is well accepted that 35% to 40% of elective, diagnostic heart catheterizations are normal. What does this say about the current workup of coronary artery disease if patients who need the treatment the most have a 50-50 chance of getting it and patients who are referred after extensive imaging workups have a 40% chance of being normal when referred to the "gold standard" exam?

The current workup of coronary artery disease is inaccurate, indirect, expensive, and wasteful. That is why use of coronary CTA is exploding worldwide. Patients are driving this change, and the reason why is very simple. They want to live longer, healthier lives and they don't care if cardiologists or radiologists win the turf war. They want the best exam, on the best equipment, interpreted by those best trained to read the exams-and that means the whole exam, including cardiac and noncardiac findings.

DR. NEWTON'S REBUTTAL

Dr. Dowe is correct to say that to most cardiologists, an MSCT scanner is an unfamiliar machine. We also share the same impression that many physicians have attended cardiac CT angiography courses where not much learning seems to have taken place.

I would add that many of the radiologists that I teach en route to competency (whose CT imaging skills are admittedly very sharp) view heart disease, particularly varying degrees of atherosclerosis, very insecurely and report it cautiously and nonspecifically. Both specialists have a lot to learn if cardiac CT is to find the superior value that it promises our patients. I simply believe that all this learning can take place quickly with good teachers from either specialty. It has to: CT is not the last of the important tools on the horizon.

Dr. Dowe correctly points out that scanning technique and protocol are critical to good imaging: dose, pitch, section thickness, injection rate, etc. But these are not complicated formulas passed down through secret societies as in The Da Vinci Code; they are all over the academic Web sites and vendor manuals.

For me as a cardiologist, here is the essence of it: Is the study technically adequate or not? Is coronary atherosclerosis present or not? Is that atherosclerosis in an important artery? Is it mild, moderate, or severe? Are the great vessels connected normally, with normal valves, to normal chambers that move normally? Are stents and bypass grafts open and how do the runoff vessels look? Are there any important noncoronary findings present?

Physicians who answer these questions reliably will drive quality decisions and economy of healthcare dollars. Will multiyear fellowships be required to do this work? Five years ago, yes. But today? I don't think so. Two years from now? Not unless turf wars prevail.

Ultimately, cardiac CT will become a straightforward, inexpensive commodity study, which is as it should be.

Dr. Dowe is chief operating officer and medical director of Atlantic Medical Imaging in Galloway, NJ.