Advanced Skeletal Muscle MR Imaging Approaches in the Assessment of Muscular Dystrophies

Abstract

Muscular dystrophies (MDs) are inherited diseases that lead to progressive skeletal muscle weakness and functional decline. Currently, the diagnosis is generally made on clinical grounds and confirmed by genetic testing, serologic assessments, neurophysiologic measurements or muscle biopsy. Given our understanding of the pathophysiology of these dystrophies, advancements in magnetic resonance imaging (MRI) techniques may assist clinicians in identification and monitoring of skeletal muscle disease progression in MDs using non-invasive approaches. In this article, we review MR imaging techniques that have been used to quantify skeletal muscle involvement in the various muscle dystrophies, such as in vivo spectroscopic procedures to quantify lipids (1H), muscle bioenergetics (31P) or cellular function (23Na). We also summarize studies that have used T2 relaxation measurements to evaluate muscular dystrophies. While carbon spectroscopy (13C), diffusion tensor imaging (DTI) and blood oxygenation level-dependent (BOLD) imaging have not yet been explored in the assessment of skeletal muscles of MD patients, we briefly describe these techniques as they have been useful in skeletal muscle examinations of healthy and injured muscles. Thus, they could potentially be of diagnostic and prognostic value in skeletal muscle evaluations of MD patients. The article concludes by commenting on potential for image processing methods such as texture analysis in the evaluation of muscle images from MD patients.