Quantitative MRI of the upper arm in Duchenne muscular dystrophy: Consistent slice positioning is crucial due to fat-fraction variability

Skeletal muscle fat fraction determined using quantitative MRI is a promising outcome measure in Duchenne muscular dystrophy (DMD). However, fat fraction varies along the length of muscles in the lower limb, hampering consistency of longitudinal assessments. Our results show that fat fraction also varies over muscles in the upper limb. This variability is reduced when assessments are standardized at 40% of the humerus length. This is important for reproducibly measuring the fat fraction in the muscles of the upper limb in DMD in clinical trials and follow-up.