Dobutamine MRI: A serious contender in pharmacological stress imaging?

Abstract

Noninvasive techniques for assessing coronary artery disease (CAD) have improved dramatically over the past 20 years. This is particularly true with the advent of pharmacological stress testing in patients who are unable to exercise. Because myocardial perfusion and function are closely coupled, state-of-the-art stress imaging modalities have involved assessment of myocardial perfusion with radionuclide techniques or wall motion with echocardiography. Echocardiography is currently the preferred method for ascertaining regional ventricular function during stress because of its high diagnostic accuracy, feasibility, versatility, and relatively low cost. Echocardiography has been combined with various stress modalities besides exercise. Of the various agents that can produce cardiovascular stress, dobutamine has been the most widely used. Results from dobutamine stress echocardiography (DSE) have been consistent with those of exercise echo and radionuclide imaging.1 2 In addition to detecting CAD, current clinical applications of DSE include risk stratification and assessment of residual myocardial viability in patients with ventricular dysfunction.1 2 3 One of the main limitations of stress echocardiography has been the suboptimal visualization of myocardial segments in 5% to 10% of patients and the need for considerable technical aptitude to acquire the images. However, DSE requires less technical prowess than does exercise echo. Image quality and delineation of endocardial motion have been greatly improved by advances in transducer technology. More recently, the discovery of harmonic imaging and the availability of intravenous contrast agents that can opacify the left ventricle4 5 6 have further enhanced the efficacy of this technique. Parallel to this evolution of echocardiography into the stress arena has been the progression of cardiac magnetic resonance imaging (MRI). Current spin-echo and gradient-echo techniques allow visualization of the heart in any tomographic plane with good spatial resolution and tissue contrast, without ionizing radiation. MRI allows excellent identification of the endocardial and epicardial …