Purpose: To investigate the correlation between muscle function and metabolism in muscle tissue of Duchenne muscular dystrophy (DMD) patients by in vivo proton magnetic resonance spectroscopy.
Materials and methods: In this prospective study, we enrolled 8 boys with DMD and 8 healthy volunteers. In vivo proton magnetic resonance spectroscopy of the soleus muscles was performed using a whole-body 3.0-Tesla imaging unit and a knee coil. The levels of trimethyl ammonium (TMA) and total creatine (tCr) were measured. We compared TMA/water, tCr/water, and TMA/tCr ratios, and scores for muscle function in the legs by using a t test.
Results: Fat infiltrated the leg muscles in all patients but no volunteers. All patients had elevated creatine kinase levels. Magnetic resonance spectra of patients and volunteers showed TMA and tCr peaks. Ratios of TMA/water (P = 0.0015), tCr/water (P = 0.0167), and TMA/tCr (P = 0.0017), and muscle function scores (P = 0.0028) were significantly lower in patients than in volunteers. All patients had impaired muscle function, whereas all volunteers had normal function. Muscle function in the legs was negatively correlated with the TMA/tCr ratio (r2 = 0.878).
Conclusions: Metabolite ratios and muscle function scores were significantly decreased in patients with DMD when compared with normal control subjects. A statistically significant decrease in TMA/tCr ratio in patients with DMD as compared with control subjects was found to correlate with decreased muscle function.