Permanent muscular sodium overload and persistent muscle edema in Duchenne muscular dystrophy: a possible contributor of progressive muscle degeneration

To assess the presence and persistence of muscular edema and increased myoplasmic sodium (Na + ) concentration in Duchenne muscular dystrophy (DMD). We examined eight DMD patients (mean age 9.5 ± 5.4 years) and eight volunteers (mean age 9.5 ± 3.2 years) with 3-tesla proton ( 1 H) and 23 Na density-adapted 3D-radial MR sequences. Seven DMD patients were re-examined about 7 months later without change of therapy. The eighth DMD patient was re-examined after 5 and 11 months under medication with eplerenone. We quantified muscle edema on STIR images with background noise as reference and fatty degeneration on T1-weighted images using subcutaneous fat as reference. Na + was quantified by a muscular tissue Na + concentration (TSC) sequence employing a reference containing 51.3 mM Na + with 5 % agarose. With an inversion-recovery (IR) sequence, we determined mainly the myoplasmic Na + . The normalized muscular 23 Na IR signal intensity was higher in DMD than in volunteers ( n = 8, 0.75 ± 0.07 vs. 0.50 ± 0.05, p