Human skeletal muscle size with ultrasound imaging: a comprehensive review

Abstract

Skeletal muscle size is an important factor in assessing adaptation to exercise training and detraining, athletic performance, age-associated atrophy and mobility decline, clinical conditions associated with cachexia, and overall skeletal muscle health. Magnetic resonance (MR) imaging and computed tomography (CT) are widely accepted as the gold standard methods for skeletal muscle size quantification. However, it is not always feasible to use these methods (e.g., field studies, bedside studies, large cohort studies). Ultrasound has been available for skeletal muscle examination for more than 50 years and the development, utility, and validity of ultrasound imaging are underappreciated. It is now possible to use ultrasound in situations where MR and CT imaging are not suitable. This review provides a comprehensive summary of ultrasound imaging and human skeletal muscle size assessment. Since the first study in 1968, more than 600 articles have used ultrasound to examine the cross-sectional area and/or volume of 107 different skeletal muscles in more than 27,500 subjects of various ages, health status, and fitness conditions. Data from these studies, supported by decades of technological developments, collectively show that ultrasonography is a valid tool for skeletal muscle size quantification. Considering the wide-ranging connections between human health and function and skeletal muscle mass, the utility of ultrasound imaging will allow it to be employed in research investigations and clinical practice in ways not previously appreciated or considered.

Reliability and validity of assessing lower‐limb muscle architecture of patients with cerebral palsy (CP) using ultrasound: A systematic review

“…For the inter‐rater reliability, both the ICC and SEM were reported for the muscle length, cross‐sectional area, muscle volume, pennation angle, and fascicle length. The corresponding ICC values were generally similar to those of the healthy population 28,41,65 . The ICC is a relative measure of reliability, and mainly concerns the consistency of the measurement position or the relative rank of an individual in the group as compared to the other's.…”

“…The intrarater reliability of ultrasound was identified for all the abovementioned parameters in CP patients by calculating the ICC, which was generally comparable to those of MRI in assessing the lowerlimb muscles of CP patients 29,32 and ultrasound in assessing healthy peers. 20,28,41 The SEM of ultrasound was only identified for the muscle length, cross-sectional area, and muscle volume. For the inter-rater reliability, both the ICC and SEM were reported for the muscle length, cross-sectional area, muscle volume, pennation angle, and fascicle length.…”

“…The corresponding ICC values were generally similar to those of the healthy population. 28,41,65 The ICC is a relative measure of reliability, and mainly concerns the consistency of the measurement position or the relative rank of an individual in the group as compared to the other's. In contrast, the SEM is a measure of absolute reliability, and mainly concerns the consistency of the scores of individuals.…”

Compensation strategy of shoulder synergist muscles is not stereotypical in patients with rotator cuff repair

“…The echo intensity fairly reflects the intramuscular fat, as shown by comparison with magnetic resonance imaging 35 and computed tomography 36 . These measures were used to quantify muscle size and intermuscular fat, as previously reported 37,38 . The B‐mode images were exported from the ultrasound system to a personal computer as tagged image format files and processed using the ImageJ software (National Institutes of Health).…”

Effect of radioiodine treatment on muscle mass in hyperthyroid cats

“…Recently, investigators have evaluated ultrasound imaging of muscle as a quantitative measure of muscle loss in humans, 22‐24 dogs, 13,25,26 and cats 27,28 . In dogs and cats, investigators measured epaxial muscle height (EMH) from transverse ultrasonographic images obtained at the level of the 13th thoracic vertebrae (T13) and validated this approach in healthy cats and cats with various degrees of muscle loss 13,25‐28 .…”