385P Quantitative magnetic resonance of masticatory muscles in adolescents with Duchenne muscle dystrophy.

The study of bulbar functions, particularly chewing, in patients with Duchenne muscular dystrophy (DMD) is an emerging field; various markers, such as fatty infiltration, have been explored. Increased fatty infiltration of masticatory muscles has been observed in muscle ultrasonography (MUSG), however, this technique has several limitations. Our aim was to measure the fat fraction (FF) of masticatory muscles using quantitative muscle resonance in DMD patients and its correlation with maximum masticatory force (MMF). Multicenter cross-sectional study in 17 healthy men (median age 16 years (interquartile range (IQR) 14-19 years), and in 11 DMD patients (median age 17, IQR 13-21 years). Bilateral MMF was measured with an oral dynamometer and MRI was performed in T1 and mDixon sequences and in the masseter, pterygoid and temporal muscles. The patients were enrolled in the study Magnetic Resonance of Orofacial and Cardiac Muscles as Biomarkers in Children and Adults with DMD. The MMF was 526 Newton (N) in controls and 156N in DMD patients (p<0.05). The muscle volumes of the muscles were 19,883 mm3 in healthy males and 19,392 mm3 in DMD patients. The mean FF was 4% in healthy men and 55% in DMD patients. Both differences were statistically significant (p<0.05). A negative correlation was observed between fatty infiltration and muscle strength (r=-0.78) in healthy patients and in DMD patients. The DMD children in this study presented significantly higher FF and lower MMF than controls. FF correlates with a lower MMF, which could be applied in the clinic and as a biomarker in clinical trials. [ABSTRACT FROM AUTHOR]