The clinical role of imaging atherosclerosis

Technological advances have facilitated a rapid expansion in the use of noninvasive coronary artery imaging. There are now numerous options offering enhanced image quality and greater anatomic definition previously unavailable without catheterization. These less invasive imaging procedures are becoming important gatekeepers, helping to select patients for catheterization in anticipation of treatment. In 10 years, for example, computed tomography (CT) has progressed from single-slice scanners to the current generation of 64-slice machines that can image the whole heart in seconds with submillimeter resolution. Consequently, multislice computed tomography (MSCT) scanning is rapidly gaining acceptance as an alternative to conventional X-ray coronary angiography. Cardiac magnetic resonance (CMR) technology has improved, too, permitting noninvasive viability testing as well as improved diagnosis of patients with coronary artery disease (CAD). Although the ultimate ability of CT and CMR to visualize the coronary lumen and wall has yet to be determined, certainly major obstruction in the proximal coronary arteries can be recognized with good accuracy. The addition of physiologic information, such as that provided by positron emission tomography (PET) often obtained from the same gantry, will further refine the accuracy of noninvasive assessment of CAD. A table is presented. A table is presented. A table is presented. Besides these new alternatives to conventional coronary angiography, even "traditional" imaging technologies have evolved. Advanced computer processing in echocardiography has increased the speed and resolution of imaging, permitting development of new modalities such as strain and synchrony imaging. In a recent editorial, Steven E. Nissen, MD, FACC, President of the ACC, acknowledged the "near-annual leapfrogs in technology" that have been evident in nuclear cardiology. These advances are resulting in a new paradigm, he said, in which highly trained "imaging specialists" employ multiple diagnostic modalities to provide answers to clinical questions. "There seems little doubt that access to multiple imaging modalities within a single practice environment can lead to more rapid and accurate diagnoses," said Dr. Nissen. Anthony N. DeMaria, MD, MACC, Editor-in-Chief of the Journal of the American College of Cardiology (JACC), also sees "a blurring of the boundaries between disciplines, and perhaps the emergence of new types of cardiologists." For example, coupling ultrasound and radioisotope procedures with the new CMR and CT techniques could form the basis for a new cardiovascular imaging specialist. There is also growing debate regarding how to use non-invasive imaging. Given the elevated risk of cardiovascular events and the higher prevalence of silent CAD in diabetic versus nondiabetic patients (Slide 1), for example, screening asymptomatic diabetic patients for CAD is an appealing concept. Two separate papers in the August 15, 2006, issue of JACC argue for and against such screening in moderate- to high-risk patients with diabetes.