Magnetic resonance imaging of regenerating and dystrophic mouse muscle

Magnetic resonance imaging allows serial visualization of living muscle. Cl inically magnetic resonance imaging would be the first step in selecting a region of interest for assessment of muscle disease state and treatment eff ects by magnetic resonance spectroscopy. In this study, magnetic resonance imaging was used to follow dystrophy and regeneration in the mdx mouse, a g enetic homologue to human Duchenne muscular dystrophy. It was hypothesized that images would distinguish normal control from mdx muscle and that regen erating areas (spontaneous and after an imposed injury) would be evident an d evolve over time. T2-weighted images of hind-limb muscles were obtained o n anaesthetized mice in a horizontal bore 7.1-T experimental magnet. Magnet ic resonance images of mdx muscle appeared heterogeneous in comparison to h omogeneous images of control muscle. Foci of high intensity in mdx images c orresponded to dystrophic lesions observed in the histologic sections of th e same muscles. In addition, it was possible to follow chronologically the extent of injury and repair after an imposed crush injury to mdx muscle. Th ese results should make it possible to obtain meaningful magnetic resonance spectra from particular regions of interest in muscle as viewed in magneti c resonance images (i.e., regenerating, degenerating, normal muscle) acquir ed during neuromuscular diseases and treatment regimens.