Upper and Lower Extremities in Duchenne Muscular Dystrophy Evaluated with Quantitative MRI and Proton MR Spectroscopy in a Multicenter Cohort

Background: Upper extremity MRI and proton MR spectroscopy are increasingly considered to be outcome measures in Duchenne muscular dystrophy (DMD) clinical trials. Purpose: To demonstrate the feasibility of acquiring upper extremity MRI and proton (H-1) MR spectroscopy measures of T2 and fat fraction in a large, multicenter cohort (ImagingDMD) of ambulatory and nonambulatory individuals with DMD; compare upper and lower extremity muscles by using MRI and H-1 MR spectroscopy; and correlate upper extremity MRI and H-1 MR spectroscopy measures to function. Materials and Methods: In this prospective cross-sectional study, MRI and H-1 MR spectroscopy and functional assessment data were acquired from participants with DMD and unaffected control participants at three centers (from January 28, 2016, to April 24, 2018). T2 maps of the shoulder, upper arm, forearm, thigh, and calf were generated from a spin-echo sequence (repetition time msec/echo time msec, 3000/20-320). Fat fraction maps were generated from chemical shift-encoded imaging (eight echo times). Fat fraction and (H2O)-H-1 T2 in the deltoid and biceps brachii were measured from single-voxel H-1 MR spectroscopy (9000/11-243). Groups were compared by using Mann-Whitney test, and relationships between MRI and H-1 MR spectroscopy and arm function were assessed by using Spearman correlation. Results: This study evaluated 119 male participants with DMD (mean age, 12 years +/- 3 [standard deviation]) and 38 unaffected male control participants (mean age, 12 years +/- 3). Deltoid and biceps brachii muscles were different in participants with DMD versus control participants in all age groups by using quantitative T2 MRI (P<.001) and H-1 MR spectroscopy fat fraction (P <.05). The deltoid, biceps brachii, and triceps brachii were affected to the same extent (P >.05) as the soleus and medial gastrocnemius. Negative correlations were observed between arm function and MRI (T2: range among muscles, rho = -0.53 to -0.73 [P<.01]; fat fraction, rho = -0.49 to -0.70 [P<.01]) and H-1 MR spectroscopy fat fraction (rho = -0.64 to -0.71; P<.01). Conclusion: This multicenter study demonstrated early and progressive involvement of upper extremity muscles in Duchenne musculardy strophy (DMD) and showed the feasibility of MRI and H-1 MR spectroscopy to track disease progression over a wide range of ages in participants with DMD. (C) RSNA, 2020