The Extracellular Matrix as a Target for Biophysical and Molecular Magnetic Resonance Imaging

All tissues and organs are composed of cells and extracellular matrix (ECM). The components of the ECM have important functional and structural roles in tissues. On the one hand, the ECM often dominates the biomechanical properties of soft tissues and provides mechanical support to the tissue. On the other hand, ECM components maintain tissue homeostasis, pH, hydration of the micromilieu, and, via signal transduction, play a key role in ECM-cell interactions, which in turn control cell migration, differentiation, growth, and death. Inflammation, fibrosis, tumor invasion, and injury are associated with the transition of the ECM from homeostasis to remodeling that can dramatically alter the biochemical and biomechanical properties of ECM components. Hence, it is possible to detect and characterize diseases by sensing biochemical and biomechanical changes in the ECM when appropriate imaging methods are used. This chapter discusses the potential of ECM-directed magnetic resonance imaging based on contrast agents and elastography from a clinical radiological perspective in a variety of diseases including atherosclerosis, cardiomyopathy, inflammation, and liver fibrosis.