Muscular Dystrophy can affect the skeletal muscles and also the heart and breathing muscles, causing significant morbidity and mortality. As patients are now living longer, treatment of muscular dystrophies involves drugs that help improve heart function. However, better types of heart imaging studies are needed to understand how these treatments work. Researchers want to improve heart imaging to identify earlier indicators of heart dysfunction in muscular dystrophy patients and how these are changed by medical treatment. The new imaging indicators will also help identify candidates for entry into future clinical trials.