Molecular Magnetic Resonance Imaging in Cardiovascular Medicine

Abstract

The ability of magnetic resonance imaging (MRI) to evaluate cardiovascular pathophysiology at several levels is one of the strengths of the technique. As shown in Figure 1, cardiac phenotype can be assessed at the whole-organ level by cine MRI, at the regional level with strain, perfusion, and viability imaging, and at the metabolic level with spectroscopic techniques.1,2 However, MRI of biological processes at the cellular and subcellular level (molecular MRI) has been studied most extensively in other disease states such as cancer.3,4 Molecular MRI techniques are, however, being increasingly developed for cardiovascular applications and, if fully developed, have the potential to make a significant impact on the practice of cardiovascular medicine. Figure 1. Comprehensive analysis of cardiac phenotype by MRI. A, cine MRI of a mouse heart; B, area of myocardial infarction delineated by delayed enhancement MRI in a mouse heart; C, corresponding triphenyltetrazolium (TTC) image. D, map of myocardial perfusion (ml/g per min) in a mouse heart obtained with a spin labeling technique;1 E, strain rate imaging at the midventricular level in a wild-type mouse;1 F, a phosphocreatine metabolite map in an isolated perfused rat heart fused with the corresponding coronary angiogram.2 Comprehensive imaging of the human heart can be performed with identical techniques. Molecular MRI thus offers the potential for complete anatomic, functional, metabolic, and molecular imaging with a single modality from bench to bedside. The advantages of an MRI-based approach to molecular imaging reflect the general attributes of the technique. MRI is noninvasive, tomographic, nonionizing, and able to generate images with high spatial resolution and excellent soft tissue contrast. In the initial portion of the present review, the technology that underlies molecular MRI agents is reviewed. The application of these agents to the imaging of myocardial disease, atherosclerosis, and stem cell …