source: Annals of Neurology
Craig M. Zaidman, Jim S. Wu, Kush Kapur, Amy Pasternak, Lavanya Madabusi, Sung Yim, Adam Pacheck, Heather Szelag, Tim Harrington, Basil T. Darras, Seward B. Rutkove
We assessed changes in quantitative muscle ultrasound data in boys with Duchenne muscular dystrophy (DMD) and healthy controls to determine if ultrasound can serve as a biomarker of disease progression. Two approaches were used: grey scale level (GSL), measured from the ultrasound image, and quantitative backscatter analysis (QBA) measured directly from the received echoes.
GSL and QBA were obtained from six unilateral arm/leg muscles in 36 boys with DMD and 28 healthy boys (age 2–14 years) for up to 2 years. We used a linear mixed-effects model with random intercept and slope terms to compare trajectories of GSL, QBA, and functional assessments. We analyzed separately a subset of boys who initiated corticosteroids.
Compared to healthy boys, increasing GSL in DMD boys >7.0 years was first identified at 6 months (e.g., anterior forearm slope difference of 1.16 arbitrary units/month p=0.004, 95% confidence interval (CI) [0.38,1.94]); in boys <=7 years, differences in GSL first appeared at 12 months (0.82 arbitrary units /month, p=0.04 95%CI [0.075,1.565] in rectus femoris). QBA performed similarly to GSL (e.g., DMD boys >7 years of 0.41dB/month, p=0.01, 95%CI [0.096,0.72] in anterior forearm at 6 months). US identified differences earlier than functional measures including 6-minute walk and supine-to-stand tests. However, neither QBA nor GSL showed an effect of corticosteroid initiation.
QBA performs similarly to GSL and both appear more sensitive than functional assessments for detecting muscle deterioration in DMD. Additional studies will be required to determine if quantitative muscle ultrasound can detect therapeutic efficacy.
Washington University in St. Louis, USA; Harvard Medical School, USA; Boston Children’s Hospital, USA; Beth Israel Deaconess Medical Center, USA
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