MR evaluation of myocardial ischemia and infarction

Magnetic resonance (MR) imaging is potentially a well-suited modality to guide clinical management of patients with myocardial ischemia and infarction. Evaluation of regional perfusion and contractile function distinguishes between normal and ischemic myocardium and identifies areas of infarction, stunning, and hibernation. Recent technical improvements in MR perfusion imaging include the use of echoplanar and fast gradient-echo sequences to capture the first pass of MR contrast agents through the myocardium. Evaluation of regional function will likely benefit from motion-encoded MR imaging, which employs tissue tagging or cine phase-contrast to track the myocardial motion throughout the cardiac cycle. Stress imaging with dobutamine and dipyridamole will further enhance the accuracy of MR myocardial imaging. Advantages of MR imaging over other available noninvasive modalities include its good spatial resolution and the potential for three-dimensional imaging without the need for geometric assumptions. Importantly, a single comprehensive MR examination can assess not only regional myocardial perfusion and function, but in addition also global ventricular size and function and (perhaps) coronary artery anatomy and flow. Such integrated cardiac evaluation may turn out to be a cost-effective strategy. Large clinical trials incorporating outcome analysis are now needed to see whether cardiac MR imaging can live up to the current high expectations.