Muscle ultrasound quantifies disease progression over time in infants and young boys with duchenne muscular dystrophy

Introduction: Quantitative muscle ultrasound (QUS) in boys with Duchenne muscular dystrophy (DMD) shows increased echointensity as muscle is replaced with fat and fibrosis. Studies of quantitative ultrasound in infants/young boys with DMD over time have not been reported. Methods: We used calibrated muscle backscatter (cMB), a reproducible measure of ultrasound echointensity, to quantify muscle pathology in 5 young boys with DMD (ages 0.5-2.8 years) over 17-29 months. We compared the results with repeated assessments of function (n=4) and with muscle ultrasound images from a cross-section of 6 male controls (0.6-3.1 years). Results: cMB in boys with DMD increased (worsened) over time (P<0.001), whereas function improved. After age 2 years, cMB in most (4 of 5) boys with DMD was higher than in any control. Conclusions: QUS measures disease progression in young boys with DMD despite functional improvements. QUS could be employed as an outcome measure for serial assessment of young boys with DMD.