MRI in ischemic heart disease: expansion of the current capabilities with MR contrast.

Magnetic resonance imaging (MRI) has been used to identify acute and chronic myocardial infarctions and the complications of myocardial infarctions. Studies in animals have shown high accuracy in the quantification of the volume (mass) of acute myocardial infarctions. However, the role of MRI in ischemic heart disease has been limited by the inability to detect noninfarctional myocardial ischemia or to reliably indicate relative myocardial perfusion. Studies in animal models of various myocardial ischemic events have shown that these aims can be addressed using MR contrast media. The effect of MR contrast media on regional myocardial signal intensity is complex and determined by several factors, including: (1) the type of contrast medium; (2) the dose of the contrast medium; (3) the T1- or T2-weighting of the imaging sequence; and (4) the type of imaging technique applied (spin echo, gradient echo, or echoplanar). This article describes some of the potential applications of MR contrast media in ischemic heart disease and the several factors that interact to cause the regional myocardial signal alterations induced by MR contrast media.