Noninvasive assessments of muscle microstructure to predict function

Skeletal muscle is a highly organized, plastic tissue, able to alter its structural and functional properties based on environmental factors such as exercise, disuse, injury, and pathology. These factors often affect muscle fiber size, a key feature of muscle microstructure directly related to muscle fiber isometric force generating capacity. Currently, the gold standard for assessing muscle fiber size is histology, which is highly invasive, destructive to the muscle, semi-quantitative, and only provides information about a fraction of the entire muscle volume. Magnetic resonance imaging (MRI) is a powerful tool, capable of producing validated quantifiable measurements of tissue structure, function, and molecular content. In this talk, we will discuss diffusion tensor MRI (DT-MRI) - a technique sensitive to tissue microstructure – and how it can be used to noninvasively “biopsy” skeletal muscle. Basic principles of this technique will be reviewed, followed by technical considerations, and validation requirements. Lastly, applications of DT-MRI to solve clinically focused problems related to muscle health as well as noninvasive monitoring of tissue engineered constructs to treat muscle injuries will be discussed. The overall goal of these experiments is to fill a clinical need for noninvasive imaging techniques that are capable of accurately assessing changes in tissue or tissue engineered constructs over time.