Quantitative Ultrasound Imaging to Assess Skeletal Muscles in Adults with Multiple Sclerosis: A Feasibility Study

The aim of this study was to assess the feasibility of quantitative ultrasound imaging (QUI) in assessing the biceps brachii muscle and gastrocnemius muscle in adults with multiple sclerosis (MS).

From May to October 2018, we prospectively performed B-mode ultrasound imaging and ultrasound strain elastography of the biceps brachii muscle and gastrocnemius muscle in 24 patients with MS and 10 age-matched healthy volunteers. ImageJ (https://imagej.nih.gov/ij) was used to assess the muscle pixel intensity in grayscale images. Using 2-dimensional speckle-tracking software, we estimated the muscle axial peak strain (maximum deformation) produced by manual compression with an ultrasound transducer and the muscle longitudinal peak strain (maximum displacement) produced by passive elbow and ankle movements. Muscle QUI parameters used in the study included the mean pixel intensity, axial peak strain ratio (SR = muscle strain/subcutaneous tissue strain), and longitudinal peak SR. Statistical analyses included 1-way analysis of variance and a post hoc test to examine the differences in QUI parameters among 3 groups (1, affected muscle in patients with MS; 2, unaffected muscle in patients with MS; and 3, healthy muscle in controls) and, in all paired groups, an unpaired t test to compare the muscle SR in patients with MS with a Modified Ashworth Scale (MAS) score of 1 or higher to those with an MAS score of 0.

The mean age of the 24 patients with MS was 43 years, and all patients and volunteers were female. We observed a significant difference in QUI parameters among the affected muscle in MS, unaffected muscle in MS, and healthy muscle in all paired groups and in patients with MS between an MAS score of 1 or higher and an MAS score of 0 (all P < .05). Interobserver and intraobserver variability in performing QUI was good (intraclass correlation coefficients >0.75).

Our results suggest that QUI is feasible to assess muscle echogenicity and mechanical behaviors in adult MS.