Magnetic resonance microscopy and histology of the CNS

High-resolution magnetic resonance (MR) imaging or MR microscopy of small animals is rapidly becoming an important tool for non-invasive assessment of the anatomy and function of various tissues, particularly the central nervous system. The availability of multiple MR modalities provides the opportunity to generate many different types of endogenous or exogenous tissue contrast, which enables new types of histology. For instance, it is possible to obtain contrast based on intrinsic differences in the chemical composition of tissue, including the presence of iron, plaques or myelin fibers. Cells can also be identified by marking with an exogenous contrast label or 'magnetic dye' before their introduction into tissue. As MR histology is non-invasive, serial studies can be performed, enabling a unique dynamic evaluation of cellular events within the same individual.