• corticosteroids;
  • Duchenne muscular dystrophy;
  • fat replacement;
  • longitudinal;
  • MRI


Introduction: In Duchenne muscular dystrophy (DMD), fat replacement of muscle may be a useful endpoint in trials of therapy, although progression in different muscle groups is uneven. In this study we assessed the progression of fat replacement with T1-weighted imaging over 2 9-month periods. Methods: Eight ambulant, corticosteroid-treated boys with DMD were imaged at 3 Tesla at 3 time-points (baseline and 9 and 18 months) with T1-weighted imaging to measure fat replacement. Results: The greatest increase in fat content was measured in the biceps femoris long head, vastus lateralis, and rectus femoris, whereas the biceps femoris short head and gluteus maximus progressed more slowly. None of the lower leg muscles studied changed significantly. Conclusions: MRI can measure specific changes in fat replacement of muscle over time, demonstrating the variability in rates of natural progression between muscle groups and identifying those muscles suitable for use as biomarkers in clinical trials. Muscle Nerve 48: 586–588, 2013