RecruitingDevelopment of Quantitative Muscle Imaging as a Biomarker of Disease Endpoints in Myotonic DystrophyMyotonic dystrophy (dystrophia myotonica; DM), the most prevalent form of muscular dystrophy in adults, is characterized by progressive myopathy, myotonia, and multi-systemic involvement. DM causes severe disability and profoundly affects the patient's quality of life. Currently, no effective treatments are available that alter the course of the disease, but ongoing clinical trials are underway.