In vivo visualization of macrophage infiltration and activity in inflammation using magnetic resonance imaging.

Because macrophages play a key role on host defense, visualization of the migration of these cells is of high relevance for both diagnostic purposes and the evaluation of therapeutic interventions. The present article addresses the use of iron oxide and gadolinium-based particles for the noninvasive in vivo detection of macrophage infiltration into inflamed areas by magnetic resonance imaging (MRI). A general introduction on the functions and general characteristics of macrophages is followed by a discussion of some of the agents and acquisition schemes currently used to track the cells in vivo. Attention is then devoted to preclinical and clinical applications in the following disease areas: atherosclerosis and myocardial infarction, stroke, multiple sclerosis, rheumatoid arthritis, and kidney transplantation.

Investigating pharmacology in vivo using magnetic resonance and optical imaging.

The better and earlier a disease can be diagnosed and characterized, the greater the chance of being able to intervene in this process with a chemical entity. This is the rationale for the use of in vivo imaging techniques in the drug discovery and development process. In this article we address the value of two imaging modalities in this area, i.e. magnetic resonance imaging (MRI) and optical imaging. The multiparametric nature of MRI enables anatomical, functional, metabolic and, to a certain extent, also cellular and target-related information to be obtained noninvasively at high spatial resolution. This favours characterization of a disease state and the corresponding drug intervention. The noninvasiveness of MRI strengthens the link between preclinical and clinical pharmaceutical research. The high sensitivity of optical techniques enables molecular information to be obtained in vivo. Within pharmacological research, the main applications of optical techniques relate to the early drug discovery process and acquisition of target-related information. However, potential clinical applications of optical imaging are also emerging. The complementary character of both imaging modalities renders them useful in various portions of the drug discovery process, from early target selection and validation to clinical studies.