Longitudinal measurements of MRI-T2 in boys with Duchenne muscular dystrophy: Effects of age and disease progression

Duchenne muscular dystrophy (DMD) is characterized by an increased muscle damage and progressive replacement of muscle by noncontractile tissue. Both of these pathological changes can lengthen the MRI transverse proton relaxation time (T2). The current study measured longitudinal changes in T2 and its distribution in the lower leg of 16 boys with DMD (5-13 years, 15 ambulatory) and 15 healthy controls (5-13 years). These muscles were chosen to allow extended longitudinal monitoring, due to their slow progression compared with proximal muscles in DMD. In the soleus muscle of boys with DMD, T2 and the percentage of pixels with an elevated T2 (⩾2 SD above control mean T2) increased significantly over 1 year and 2 years, while the width of the T2 histogram increased over 2 years. Changes in soleus T2 variables were significantly greater in 9-13 years old compared with 5-8 years old boys with DMD. Significant correlations between the change in all soleus T2 variables over 2 years and the change in functional measures over 2 years were found. MRI measurement of muscle T2 in boys with DMD is sensitive to disease progression and shows promise as a clinical outcome measure.