Proton spin-lattice relaxation time of Duchenne dystrophy skeletal muscle by magnetic resonance imaging

By means of proton MRI, the spin-lattice relaxation times (T1 values) of pelvic and leg muscles were measured in Duchenne muscular dystrophy (DMD) patients and normal controls. The bound water fraction (BWF) was calculated from the T1 value obtained. In normal children, the T1 value decreased, and BWF increased with age. In DMD, the T1 value rapidly decreased, from an abnormally high value in the early stages, with the progress of the disease. This reduction of the T1 value in DMD was not the same for all muscles; it was most prominent in the gluteus maximus and least prominent in the sartorius and gracilis muscles. BWF was below normal in the early stages of DMD. It is suggested that both regenerating and degenerating muscle fibers, together with the increased muscle water content, cause the high T1 value and low BWF in the early stages of DMD, whereas replacement of muscle by fat causes the decreased T1 value in the advanced stages.