Validation of shear wave elastography in skeletal muscle

Abstract

Skeletal muscle is a very dynamic tissue, thus accurate quantification of skeletal muscle stiffness throughout its functional range is crucial to improve the physical functioning and independence following pathology. Shear wave elastography (SWE) is an ultrasound-based technique that characterizes tissue mechanical properties based on the propagation of remotely induced shear waves. The objective of this study is to validate SWE throughout the functional range of motion of skeletal muscle for three ultrasound transducer orientations. We hypothesized that combining traditional materials testing (MTS) techniques with SWE measurements will show increased stiffness measures with increasing tensile load, and will correlate well with each other for trials in which the transducer is parallel to underlying muscle fibers. To evaluate this hypothesis, we monitored the deformation throughout tensile loading of four porcine brachialis whole-muscle tissue specimens, while simultaneously making SWE measurements of the same specimen. We used regression to examine the correlation between Young's modulus from MTS and shear modulus from SWE for each of the transducer orientations. We applied a generalized linear model to account for repeated testing. Model parameters were estimated via generalized estimating equations. The regression coefficient was 0.1944, with a 95% confidence interval of (0.1463 – 0.2425) for parallel transducer trials. Shear waves did not propagate well for both the 45° and perpendicular transducer orientations. Both parallel SWE and MTS showed increased stiffness with increasing tensile load. This study provides the necessary first step for additional studies that can evaluate the distribution of stiffness throughout muscle.

Acoustic Radiation Force Impulse (ARFI) elastography quantification of muscle stiffness over a course of gradual isometric contractions: a preliminary study.

“…Although the utility of this technique in the quantitative analysis of muscle stiffness has been studied by various groups, determining suitable applications of these methods, particularly in routine medical practice, will take time. In this regard, studies aimed at figuring out new areas of usage for US elastography, partially shear-wave elastography, as an assessment method for muscle tissue in relevant clinicopathological aspects, have been recently published [20,25,26,[28][29][30][31].…”

“…This is in agreement with the study of Gennisson et al, which deduced that the resting stiffness of the muscle can be a predictive indicator for estimating the further stiffness levels of the muscle at sub-maximal contracting aspects. An in vitro study using a porcine brachialis whole-muscle tissue specimen model was performed by Eby et al to investigate the validation of SWE throughout the functional range of motion of skeletal muscle for three ultrasound transducer orientations [20]. This study confirmed that the orientation of the ultrasound probe affected the results when assessing the SWE shear modulus throughout the normal range of tension of appendicular skeletal muscle, possibly because the shear waves propagate much more readily along fibers, rather than across them [20,25].…”

“…In comparison, only a limited number of studies in the literature have reported the validity of using US elastography in clinical practice for patients with musculoskeletal issues. In these studies, the shear wave elastography (SWE) technique was mostly used to evaluate the normal-physiological parameters of the muscle and tendon components [20][21][22][23][24]. Although these works provided innovative ideas for future studies, they were mostly experimental in design and no practical implementation of US elastography use in the clinical examination of voluntary muscle contraction has been suggested to date.…”

Reliable Protocol for Shear Wave Elastography of Lower Limb Muscles at Rest and During Passive Stretching

“…Kot et al (2012) found that the size of the region of interest (ROI) and the probe pressure influenced elastography measurement. Moreover, subject position affects the measurement: an increase of the shear modulus was observed when muscle is passively stretched, both in vitro (Shinohara et al, 2010;Maïsetti et al, 2012;Koo et al, 2013) and ex vivo (Eby et al, 2013). Maïsetti et al (2012) and Hug et al (2013) determined in vivo the slack length of the muscle, corresponding to a range of motion in which the muscle does not produce any passive force and in which shear modulus was constant.…”

No association between passive material property and cross-sectional area in human hamstring

“…The shear modulus is theoretically proportional to the square of the shear wave speed. Muscle shear modulus assessed by ultrasound SWE has been shown to be highly correlated (r 2 ≥ 0.916) with muscle Young's modulus measured by a traditional material (i.e., stress-strain) test 20) . Additionally, the validity and repeatability of the ultrasound SWE measurements has been demonstrated in phantom and human experiments in our recent works [12][13][14] .…”