Editorial: Coronary artery CTA: A new frontier

Dr. Mirvis is the Editor-in-Chief of this journal and a Professor of Radiology, Diagnostic Imaging Department, University of Maryland Medical Center, Baltimore, MD.

During the 2005 RSNA meeting there were, as usual, a number of topics that seemed to catch the attention of the crowd. The most popular topics are usually obvious, since there is standing room only at these presentations. This year, the topic of coronary artery CT angiography (CA-CTA) was clearly one of the dominant themes of the meeting. Since our department is now providing the "triple rule-out" study (that, for the non-emergency-oriented among us, is myocardial ischemia, pulmonary embolism, and acute aortic syndrome), I thought that it might be wise to spend some time brushing up on technical aspects and details of interpretation. The interest level was exceptional, and I have never noticed so many people-including myself-taking notes at the lectures on this subject.

The availability of multidetector CT-especially the newest 40- and 64-slice scanners-made the performance of CA-CTA practical, very rapid, noninvasive, and highly accurate. The ability to identify areas of critical vascular narrowing as well as to characterize the physical nature of plaques in terms of constituents (ie, lipid, fibrous, calcified) is a significant value that this technique adds. The identification of "vulnerable" plaque or ruptured plaque provides a new frontier in coronary artery imaging. The presentation of patients with acute chest pain accounts for 5 million emergency room visits annually in the United States, but acute myocardial infarction is responsible for this symptom in only 10% of these patients. ¹ While medical history and physical examination remain critical, and analysis of cardiac enzymes is often very helpful in determining which patient has pain of cardiac origin, the question often remains unresolved, typically requiring costly admission and observation. In some cases, only invasive and expensive coronary angiography can resolve the diagnostic dilemma.

With CA-CTA, we can reliably evaluate the results of interventions in the coronary vasculature, including bypass grafts, dilatations, and stenting. ² The potential to noninvasively follow the regression of coronary artery plaques in patients undergoing "statin" therapy struck me as another great potential value of CA-CTA. ³ While there is appropriate concern about the radiation exposure required to achieve high image quality for this procedure, the use of dose-adjustment during the cardiac cycle (electrocardiographic modulation) should permit a routine decrease of 30% to 50% from current levels. ⁴

Radiology, as a specialty, must promote and continue to perfect this technique and unequivocally establish its role in assessing coronary artery pathology and its treatment. Radiologists should continue to evaluate the impact that this technique can have in accurately verifying the presence of cardiac ischemia (both acute and chronic), in lowering the cost of the diagnosis of coronary artery disease, and in favorably impacting short- and long-term patient outcome. At the same time, we must reinvigorate our understanding of cardiac physiology and pathology in order to contribute as much as possible to optimizing clinical decision making in treating this all too common disease.