Value of blood pool MR contrast agents in imaging of the heart and blood vessels.
Magnetic resonance (MR) imaging has emerged as a new diagnostic technique for evaluation of the cardiovascular system. The diagnostic benefits of MR contrast agents have been demonstrated in the laboratory and in clinical research that has taken place during the past 12 years. Contrast agents enhance the sensitivity of MR angiography and improve early detection and characterization of myocardial and microvascular injuries. Clinically approved MR contrast agents are not confined to the intravascular space due to their small molecular size (standard extracellular MR contrast agents) and, therefore, they produce peak vascular enhancement for only a short period of time (< 30 min). In recent years remarkable progress has been seen in the development of blood pool agents for MR imaging. Impetus for creation of these agents has come in part from a growing appreciation of MR angiography. Vascular mapping has become an important application of medical imaging. Ample experimental evidence has shown that blood pool agents may play a significant role in coronary, peripheral and pulmonary angiography. In addition to their ability to increase vascular contrast, blood pool agents provide physiological information such as rate of entry, rate of accumulation and rate of elimination. In the heart, blood pool contrast agents are useful for estimating relative myocardial perfusion, discriminating between occlusive and reperfused infarction, differentiating between reversible and irreversible myocardial injury and detecting microvascular integrity. Blood pool agents are currently being investigated in humans. Initial clinical trials have demonstrated their safety and feasibility and, hopefully, future trials will demonstrate their efficacy. The purpose of this review is to focus on the rationale and value of blood pool MR contrast agents in imaging of the heart and blood vessels.
Saeed
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Department of Radiology, University of California San Francisco, 94143-0628, USA.