Quantitative magnetic resonance imaging of the mdx mouse model of Duchenne muscular dystrophy.

The mdx mouse has a genetically homologous disease to Duchenne muscular dystrophy in humans. The disease progression, however, is not accompanied by the same level of fatty infiltration and muscle degeneration as occurs in humans. Thus, the presence of histological/pathological changes in living mdx mice has been difficult to monitor. We quantified proton density and the T2 relaxation time of protons with a resolution of 195 x 195 x 1000 microm using multiecho magnetic resonance (MR) imaging at 7 Tesla. These relaxation data were correlated with water content in both muscle and brain of mdx and controls. No differences were observed in brain. The mdx muscles had increased water content and proton density and decreased T2 relative to controls. These data indicate that there are intrinsic changes in T2 (opposite to that which would be induced by fatty infiltration) and suggest that T2 imaging could be used to monitor progression and treatment in this animal model.