CHARACTERIZATION OF REVERSIBLE MYOCARDIAL DYSFUNCTION BY MAGNETIC-RESONANCE-IMAGING

Some recent cardiovascular applications of nuclear magnetic resonance imaging (MRI) are discussed, on the basis of both literature and personal data. Management of coronary patients has become directed to strategies aiming at salvaging the ischemic myocardium, and MRI can play an important role in providing the necessary data leading to an appropriate assessment. Due to its capability in showing morphofunctional information on wall thickness and thickening, cine-MRI technique can be used to detect myocardial ischemia and infarction, since it allows the acquisition of 16 or more frames of the cardiac cycle which can be displayed in a cine loop format. In an Italian Cooperative Study the role of MRI in discriminating stunned from necrotic areas has been investigated. Comparison of fractional area change by echo versus cine-MR turned out to be almost completely overlapping, but cine-MRI allowed a more accurate measurement of systolic wall thickening due to better visualization of endo- and epicardial borders (more sensitive marker of kinetic damage than wall motion). Other studies have also been performed in order to determine the capability of contrast agents of allowing differentiation between reperfused reversible and irreversible myocardial injury and allowing distinction between reperfused and occlusive myocardial infarction. In a recent study we investigated the MRI possibility of identifying viable myocardium in severely chronic systolic dysfunctioning areas by comparing, in corresponding left ventricular segments, regional perfusion and metabolism at IPPA scintigraphy and regional signal intensity at MR images obtained before and after paramagnetic contrast media administration. The potential role of MRI was shown in the identification of viable myocardium with the use of contrast medium, that is of crucial importance in this respect.