Noninvasive coronary artery imaging in the diagnosis and management of patients with ischemic heart disease

The inherent limitations of x-ray coronary angiography have led to the development for both noninvasive and minimally invasive techniques for imaging the coronary arteries to assist in the diagnosis and management of patients with ischemic heart disease. Significant advances in transesophageal echocardiography, electron beam computed tomography, and magnetic resonance imaging now permit imaging of the proximal to midcoronary arteries. Moreover, results of initial studies demonstrate the promise of these methods to detect coronary artery stenoses. In addition, each of these methods provides biochemical or physiologic data about the stenoses that are not obtainable through x-ray angiography. Quantification of coronary calcification via electron beam computed tomography has shown promise as a surrogate marker of coronary atherosclerosis. Transesophageal echocardiography and magnetic resonance imaging appear useful in evaluating the physiologic significance of angiographically detectable coronary artery stenoses via assessment of coronary blood flow. However, it should be noted that significant improvements in technology or acquisition parameters must occur before these techniques can be used on a routine clinical basis for coronary artery imaging. The relative merits and ultimate clinical potential of each of these techniques are discussed in this article.