scholarly journals Axial Stress Provides a Lower Bound on Shear Wave Velocity in Active and Passive Muscle

2021 ◽  
Author(s):  
Michel Bernabei ◽  
Sabrina S. M. Lee ◽  
Eric J. Perreault ◽  
Thomas G. Sandercock
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Axial Stress ◽  
Muscle Length ◽  
Muscle Stiffness ◽  
Medial Gastrocnemius ◽  
Active Muscle ◽  
Muscle Stress ◽  
Stress Dependent

ABSTRACTUltrasound shear wave elastography can be used to characterize mechanical properties of unstressed tissue by measuring shear wave velocity (SWV), which increases with increasing tissue stiffness. Measurements of SWV have often been assumed to be directly related to the stiffness of muscle. Some have also used measures of SWV to estimate stress, since muscle stiffness and stress covary during active contractions. However, few have considered the direct influence of muscle stress on SWV, independent of the stress-dependent changes in muscle stiffness, even though it is well known that stress alters shear wave propagation. The objective of this study was to determine how well the theoretical dependency of SWV on stress can account for measured changes of SWV in passive and active muscle. Data were collected from six isoflurane-anesthetized cats; three soleus muscles and three medial gastrocnemius muscles. Muscle stress and stiffness were measured directly along with SWV. Measurements were made across a range of passively and actively generated stresses, obtained by varying muscle length and activation, which was controlled by stimulating the sciatic nerve. Our results show that SWV depends primarily on the stress in a passively stretched muscle. In contrast, the SWV in active muscle is higher than would be predicted by considering only stress, presumably due to activation-dependent changes in muscle stiffness. Our results demonstrate that while SWV is sensitive to changes in muscle stress and activation, there is not a unique relationship between SWV and either of these quantities when considered in isolation.

scholarly journals Effect of prolonged sitting immobility on shear wave velocity of the lower leg muscles in healthy adults: A proof-of-concept study

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251532
Author(s):  
Kumiko Okino ◽  
Mitsuhiro Aoki ◽  
Masahiro Yamane ◽  
Chikashi Kohmura
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Tibialis Anterior ◽  
Lower Leg ◽  
Medial Gastrocnemius ◽  
Adult Males ◽  
Cellular Space ◽  
Leg Muscles ◽  
Physical Changes

Objective The purpose of this study is to investigate the physical changes of the lower leg muscles in the compartment by observing the changes in the shear wave velocity of the gastrocnemius, soleus and tibialis anterior muscles with time in the sitting position for 2 hours and after elevation of the lower leg. Materials and methods The subjects were 24 healthy adult males (average age 26.6 years). Shear wave velocity was measured by Aplio 500 in immobilized leg immediately after the start of sitting, 60 minutes and 120 minutes after the start of sitting. After 120 minutes the subjects raised the lower leg for 3 minutes, then measured again. Results In the lateral and medial gastrocnemius, there was a significant increase in the velocity at 60 (1.58 ± 0.06, 1.70 ± 0.09 m/s) and 120 minutes (1.70 ± 0.10, 1.83 ± 0.11 m/s) after the start of the test (1.52 ± 0.06, 1.66 ± 0.10 m/s), respectively (p<0.01). In the soleus and the tibialis anterior, there was a significant increase in the velocity at 120 minutes (1.89 ± 0.17, 2.30 ± 0.24 m/s) compared to after the start (1.60 ± 0.15, 2.15 ± 0.26 m/s), respectively (p<0.01). In all muscles, there was a significant decrease in the velocity after the raising compared to that of 120 minutes (p<0.01). Conclusions It has been reported that the change of shear wave velocity with time is proportional to the intramuscular pressure in the leg compartment, and it is assumed that the increase of shear wave velocity in the 2-hour seated leg is due to fluid retention in extra-cellular space of the compartment.

Mapping the relationships between joint stiffness, modeled muscle stiffness, and shear wave velocity

2020 ◽  
Vol 129 (3) ◽  
pp. 483-491
Author(s):  
Andrew D. Vigotsky ◽  
Elliott J. Rouse ◽  
Sabrina S. M. Lee
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Joint Stiffness ◽  
Muscle Stiffness ◽  
Plantar Flexors ◽  
Velocity Changes ◽  
Exact Relationship

Shear wave velocity is commonly assessed to infer the muscular origins of changes in joint stiffness, but the exact relationship between shear wave velocity changes in muscle and joint stiffness changes remains unknown. Here, we systematically evaluated and quantified this relationship in the plantar flexors. Our results provide evidence for the ability of shear wave velocity to elucidate the muscular origins of joint stiffness changes.

scholarly journals Shear wave velocity is sensitive to changes in muscle stiffness that occur independently from changes in force

2020 ◽  
Vol 128 (1) ◽  
pp. 8-16 ◽  
Author(s):  
Michel Bernabei ◽  
Sabrina S. M. Lee ◽  
Eric J. Perreault ◽  
Thomas G. Sandercock
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Material Properties ◽  
Muscle Stiffness ◽  
Ultrasound Elastography ◽  
Muscle Temperature ◽  
Contracting Muscle ◽  
Muscle Structure ◽  
Direct Measurements

Clinical assessments for many musculoskeletal disorders involve evaluation of muscle stiffness, although it is not yet possible to obtain quantitative estimates from individual muscles. Ultrasound elastography can be used to estimate the material properties of unstressed, homogeneous, and isotropic materials by tracking the speed of shear wave propagation; these waves propagate faster in stiffer materials. Although elastography has been applied to skeletal muscle, there is little evidence that shear wave velocity (SWV) can directly estimate muscle stiffness since this tissue violates many of the assumptions required for there to be a direct relationship between SWV and stiffness. The objective of this study was to evaluate the relationship between SWV and direct measurements of muscle force and stiffness in contracting muscle. Data were collected from six isoflurane-anesthetized cats. We measured the short-range stiffness in the soleus via direct mechanical testing in situ and SWV via ultrasound imaging. Measurements were taken during supramaximal activation at optimum muscle length, with muscle temperature varying between 26°C and 38°C. An increase in temperature causes a decrease in muscle stiffness at a given force, thus decoupling the tension-stiffness relationship normally present in muscle. We found that increasing muscle temperature decreased active stiffness from 4.0 ± 0.3 MPa to 3.3 ± 0.3 MPa and SWV from 16.9 ± 1.5 m/s to 15.9 ± 1.6 m/s while force remained unchanged (mean ± SD). These results demonstrate that SWV is sensitive to changes in muscle stiffness during active contractions. Future work is needed to determine how this relationship is influenced by changes in muscle structure and tension. NEW & NOTEWORTHY Shear wave ultrasound elastography is a noninvasive tool for characterizing the material properties of muscle. This study is the first to compare direct measurements of stiffness with ultrasound measurements of shear wave velocity (SWV) in a contracting muscle. We found that SWV is sensitive to changes in muscle stiffness, even when controlling for muscle tension, another factor that influences SWV. These results are an important step toward developing noninvasive tools for characterizing muscle structure and function.

scholarly journals Relationship between SW velocity and muscle activation is inconsistent across different muscle types

2021 ◽  
Author(s):  
Michel Bernabei ◽  
Thomas G. Sandercock ◽  
Eric J. Perreault ◽  
Sabrina S. M. Lee
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Muscle Activation ◽  
Muscle Length ◽  
Relative Length ◽  
Pennation Angle ◽  
Ultrasound Elastography ◽  
Muscle Types ◽  
The Relationship

ABSTRACTThere is an increasing use of shear wave ultrasound elastography to quantify material properties of muscles under various conditions such as muscle length, levels of activation, in healthy and pathological muscle. However, little is known about the variability in shear wave velocity among muscles. The purpose of this study was to assess the variability of the relationship between SWV and activation across muscles with different architecture, specifically pennation angle: biceps brachii (parallel), tibialis anterior (moderately pennate), gastrocnemius (highly pennate). We tested these muscles at matching levels of activation and similar muscle lengths, relative to optimal length, to limit differences in force across muscles. Shear wave velocity-squared increased with higher levels of muscle activation (p<0.001), but the relationship between shear wave velocity-squared and activation was different across all three muscles (p<0.001). This indicates that SWV was inconsistent across muscle types, even when considering similar levels of activation and torque production. Under passive conditions, shear wave velocity-squared covaried with muscle length and was different across muscles (p<0.001), even at shortest lengths, when differences due to passive force were minimal. Variation of shear wave velocity-squared was only partially explained by changes in pennation angle during contraction (p = 0.004, R2 = 0.4). Our findings suggest that the shear wave velocity varies across muscles under passive and active conditions even when relative length is considered and that shear wave velocity may be dependent on other muscle properties, other than pennation angle, that are different between the three muscles.

scholarly journals Calibrating a new attenuation curve for the Dead Sea region using surface wave dispersion surveys in sites damaged by the 1927 Jericho earthquake

Solid Earth ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 379-390 ◽  
Author(s):  
Yaniv Darvasi ◽  
Amotz Agnon
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Dead Sea ◽  
Attenuation Curve ◽  
Surface Wave Dispersion ◽  
Near Surface ◽  
Moderate Seismicity ◽  
Local Point ◽  
The Dead

Abstract. Instrumental strong motion data are not common around the Dead Sea region. Therefore, calibrating a new attenuation equation is a considerable challenge. However, the Holy Land has a remarkable historical archive, attesting to numerous regional and local earthquakes. Combining the historical record with new seismic measurements will improve the regional equation. On 11 July 1927, a rupture, in the crust in proximity to the northern Dead Sea, generated a moderate 6.2 ML earthquake. Up to 500 people were killed, and extensive destruction was recorded, even as far as 150 km from the focus. We consider local near-surface properties, in particular, the shear-wave velocity, as an amplification factor. Where the shear-wave velocity is low, the seismic intensity far from the focus would likely be greater than expected from a standard attenuation curve. In this work, we used the multichannel analysis of surface waves (MASW) method to estimate seismic wave velocity at anomalous sites in Israel in order to calibrate a new attenuation equation for the Dead Sea region. Our new attenuation equation contains a term which quantifies only lithological effects, while factors such as building quality, foundation depth, topography, earthquake directivity, type of fault, etc. remain out of our scope. Nonetheless, about 60 % of the measured anomalous sites fit expectations; therefore, this new ground-motion prediction equation (GMPE) is statistically better than the old ones. From our local point of view, this is the first time that integration of the 1927 historical data and modern shear-wave velocity profile measurements improved the attenuation equation (sometimes referred to as the attenuation relation) for the Dead Sea region. In the wider context, regions of low-to-moderate seismicity should use macroseismic earthquake data, together with modern measurements, in order to better estimate the peak ground acceleration or the seismic intensities to be caused by future earthquakes. This integration will conceivably lead to a better mitigation of damage from future earthquakes and should improve maps of seismic hazard.

scholarly journals Multi-method site characterization to verify the hard rock (Site Class A) assumption at 25 seismograph stations across Eastern Canada

2021 ◽  
pp. 875529302110010
Author(s):  
Sameer Ladak ◽  
Sheri Molnar ◽  
Samantha Palmer
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Hard Rock ◽  
Site Characterization ◽  
Eastern Canada ◽  
Site Class ◽  
Paleozoic Rock ◽  
Rock Types ◽  
Site Period

Site characterization is a crucial component in assessing seismic hazard, typically involving in situ shear-wave velocity ( VS) depth profiling, and measurement of site amplification including site period. Noninvasive methods are ideal for soil sites and become challenging in terms of field logistics and interpretation in more complex geologic settings including rock sites. Multiple noninvasive active- and passive-seismic techniques are applied at 25 seismograph stations across Eastern Canada. It is typically assumed that these stations are installed on hard rock. We investigate which site characterization methods are suitable at rock sites as well as confirm the hard rock assumption by providing VS profiles. Active-source compression-wave refraction and surface wave array techniques consistently provide velocity measurements at rock sites; passive-source array testing is less consistent but it is our most suitable method in constraining the rock VS. Bayesian inversion of Rayleigh wave dispersion curves provides quantitative uncertainty in the rock VS. We succeed in estimating rock VS at 16 stations, with constrained rock VS estimates at 7 stations that are consistent with previous estimates for Precambrian and Paleozoic rock types. The National Building Code of Canada uses solely the time-averaged shear-wave velocity of the upper 30 m ( VS30) to classify rock sites. We determine a mean VS30 of ∼ 1600 m/s for 16 Eastern Canada stations; the hard rock assumption is correct (>1500 m/s) but not as hard as often assumed (∼2000 m/s). Mean variability in VS30 is ∼400 m/s and can lead to softer rock classifications, in particular, for Paleozoic rock types with lower average rock VS near the hard/soft rock boundary. Microtremor and earthquake horizontal-to-vertical spectral ratios are obtained and provide site period classifications as an alternative to VS30.

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