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 (T 2 ). The current study measured longitudinal changes in T 2 and its distribution in the lower leg of 16 boys with DMD (5–13years, 15 ambulatory) and 15 healthy controls (5–13years). 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, T 2 and the percentage of pixels with an elevated T 2 (⩾2SD above control mean T 2 ) increased significantly over 1year and 2years, while the width of the T 2 histogram increased over 2years. Changes in soleus T 2 variables were significantly greater in 9–13years old compared with 5–8years old boys with DMD. Significant correlations between the change in all soleus T 2 variables over 2years and the change in functional measures over 2years were found. MRI measurement of muscle T 2 in boys with DMD is sensitive to disease progression and shows promise as a clinical outcome measure.