Muscle magnetic resonance imaging of Duchenne muscular dystrophy

Abstract

Objective To evaluate the magnetic resonance imaging (MRI) changes of fatty infiltration in the thigh muscles of Duchenne muscular dystrophy (DMD) and related risk factors. Methods MRI was performed in the thigh muscles in 48 patients with DMD. Analysis of T1 images enabled us to describe muscle fatty infiltration and short inversion time inversion recovery images to describe muscle edema. The relationships between muscle fatty infiltration and body mass index, age, disease course and severity of muscle dystrophin loss were investigated. Results Forty-seven cases presented with muscle fatty infiltration and 30 cases presented with muscle edema. The mean fatty infiltration scores were over 1.5 in the adductor magnus, gluteus maximus, quadriceps and biceps femoris, which were mainly related to standing. The scores were between 1.0—1.5 in the semimembranosus and semitendinosus, which were mainly related to flexing knees. The scores were below 1.0 in the sartorius, adductor longus and gracilis, which were related to adduction of hip joints. The severity of fatty infiltration in muscles was significantly correlated with body mass index (r=0.395，P=0.013), age (r=0.693, P=0.000) and disease course(r=0.517, P=0.000), but not with the degree of muscle edema and dystrophin loss in muscles. Conclusions The differences between fatty infiltration in the thigh muscles might depend on the motor development process from stand-up to walking in the affected children. In addition to age and disease course, adiposity is a risk factor for muscle fatty infiltration in DMD. Key words: Muscular dystrophy; Duchenne; Muscle; skeletal; Magnetic resonance imaging; Body mass index