Influence of subjects' characteristics and technical variables on muscle stiffness measured by shear wave elastosonography

Assessing the Elasticity of the Flexor Pronator Muscles After Throwing Using Ultrasound Shear Wave Elastography

Background

The medial ulnar collateral ligament (UCL) of the elbow joint is the primary restraint to valgus stress during the throwing motion. The flexor pronator muscles (FPMs) also stabilize the elbow joint against valgus forces; however, assessment of FPM stiffness in baseball players has been limited.

Purpose

To use ultrasound shear wave elastography (USWE) to evaluate the change in tissue elasticity of the FPMs due to pitching.

Study Designs

Descriptive laboratory study.

Methods

Included were 14 healthy male amateur baseball players (mean age, 28.0 ± 2.6 years) who had played intermediate-level high school or college baseball. The tissue elasticity of the flexor digitorum superficialis (FDS) in the superficial layer of the FPMs and the flexor digitorum profundus (FDP) in the deep layer of the FPMs were measured using USWE before, immediately after, and 24 hours after a throwing session of 100 pitches. The intra- and interrater reliability of the measurements were evaluated using the Pearson correlation coefficient and intraclass correlation coefficient (ICC). The elasticity of each muscle was analyzed using repeated-measures analysis of variance followed by post hoc analysis.

Results

Reliability of the USWE measurements was good to excellent (intrarater ICCs, 0.78-0.94; interrater ICCs, 0.85-0.96). The mean tissue elasticity values before, immediately after, and 24 hours after pitching were 22.3 ± 4.4, 41.0 ± 13.8, and 38.3 ± 11.2 kPa, respectively, for the FDS and 27.1 ± 5.8, 48.0 ± 22.3, and 29.6 ± 11.5 kPa, respectively, for the FDP. For both the FDS and FDP, elasticity was significantly higher immediately after pitching than before pitching (P < .001 and P = .0027, respectively). While the elasticity of the FDS at 24 hours after pitching remained significantly higher compared with before pitching (P = .0011), the elasticity of the FDP at 24 hours decreased to the same level as before pitching (P = .91).

Conclusion

Results using USWE indicated that the elasticity of the FDS did not decrease 24 hours after pitching and remained significantly higher than before pitching, suggesting that it may not be fully functioning as a dynamic stabilizer during this period.

Clinical Relevance

Pitching in such a condition may result in greater stress on the UCL and increase the risk of UCL injury.

Sex-based differences in hamstrings stiffness assessment in football players using ultrasound shear wave elastography

Background

Hamstring stiffness varies among individuals and can influence athletic performance and injury risk. Sex-based differences in hamstring stiffness among football players have not been thoroughly investigated. This study aimed to assess these differences using shear wave elastography (SWE), a non-invasive ultrasound technique that quantifies tissue stiffness.

Methods

The study recruited 30 football players (15 male, 15 female) in June 2022 during their annual medical check-up. Participants were aged 18-40 years, engaged in regular training, and had no history of lower limb musculoskeletal injury in the six weeks preceding the study. SWE was used to measure shear wave velocity (SWV) in the hamstring muscles: semitendinosus (ST), semimembranosus (SM), and biceps femoris (BF). Independent t-tests were used to compare the SWV values of the hamstring muscles between sexes and between dominant and non-dominant legs.

Results

ST muscle had a statistically significant difference in SWV based on gender and leg dominance with marked differences particularly in the non-dominant leg across both genders (P=0.02; Bonferroni corrected P=0.05). SWV for ST in male group was significantly higher than that in female group; the mean elasticity of the male group for dominant and non-dominant leg were 3.8±1.5 and 4.1±1.2 m/s, respectively; and the mean elasticity of the female group for dominant and non-dominant leg were 2.9±0.7 and 2.8±0.7 m/s respectively. In contrast, SWV differences in the SM and BF muscles were not statistically significant (P=0.187 and 0.760, respectively).

Conclusions

The study revealed significant sex-based differences in hamstring stiffness among football players, as assessed by SWE. ST muscle stiffness was associated with higher SWV in male group and show stronger correlation with non-dominance leg. These findings can contribute to individualized training programs and injury prevention strategies.

Multidimensional Ultrasound Evaluation of Diastasis Recti Abdominis During Different Gestational Periods

OBJECTIVE

The purpose of this study is to explore the application value of two-dimensional ultrasound and shear wave elastography (SWE) in the multidimensional evaluation of diastasis recti abdominis (DRA) during different gestational periods.

METHODS

A cohort of 202 gravidas that were examined in our hospital between June 2021 and September 2022 were selected for the purpose of the study, which included 26 cases with <14 weeks of pregnancy, 36 cases in the 14th-27th week of pregnancy, 36 cases in the 28th-34th week of pregnancy, 32 cases in the 35th-38th week of pregnancy, 45 cases at 42 days postpartum, and 27 cases at 3 months postpartum. The inter-rectus distance (IRD) and the thickness in each gestational period were measured, and Young's modulus of the rectus abdominis at different gestational periods was measured using SWE by two sonographers. The differences in IRD, thickness, and elasticity characteristics during different periods, and the correlation between rectus abdominis elasticity and IRD, thickness, body mass index (BMI), neonatal weight, and delivery mode were analyzed and compared. The consistency of SWE parameters obtained by different sonographers was also compared.

RESULTS

There were significant differences in IRD, thickness, and Young's modulus during different gestational periods (P = .000, P < .001, P < .001). Early postpartum IRD and Young's modulus did not restore to the level of early pregnancy (P < .001, P < .001), while the thickness of rectus abdominis was not significantly different from that of early pregnancy (P = .211). The Young's modulus of rectus abdominis was negatively correlated with the IRD (r = .515), positively correlated with the thickness of rectus abdominis (r = .408), and weakly negatively correlated with maternal BMI (r = -.296). There was no significant correlation with neonatal weight or delivery mode (P = .147, .648). The Bland-Altman plot showed that the two sonographers had good consistency in evaluating the elasticity of rectus abdominis by SWE.

CONCLUSION

The multidimensional evaluation of DRA by ultrasound is feasible and IRD and Young's modulus can be used to evaluate the postpartum recovery of DRA. The combination of the two can objectively reflect the severity of DRA morphology and function.

Measuring Shear Wave Velocity in Adult Skeletal Muscle with Ultrasound 2-D Shear Wave Elastography: A Scoping Review

Ultrasound 2-D shear wave elastography (US 2D-SWE) is a non-invasive, cost-effective tool for quantifying tissue stiffness. Amidst growing interest in US 2D-SWE for musculoskeletal research, it has been recommended that shear wave velocity (SWV) should be reported instead of elastic moduli to avoid introducing unwanted error into the data. This scoping review examined the evolving use of US 2D-SWE to measure SWV in skeletal muscle and identified strengths and weaknesses to guide future research. We searched electronic databases and key review reference lists to identify articles published between January 2000 and May 2021. Two reviewers assessed the eligibility of records during title/abstract and full-text screening, and one reviewer extracted and coded the data. Sixty-six studies met the eligibility criteria, of which 58 were published in 2017 or later. We found a striking lack of consensus regarding the effects of age and sex on skeletal muscle SWV, and widely variable reliability values. Substantial differences in methodology between studies suggest a pressing need for developing standardized, validated scanning protocols. This scoping review illustrates the breadth of application for US 2D-SWE in musculoskeletal research, and the data synthesis exposed several notable inconsistencies and gaps in current literature that warrant consideration in future studies.

Characterizing Musculoskeletal Tissue Mechanics Based on Shear Wave Propagation: A Systematic Review of Current Methods and Reported Measurements

Developing methods for the non-invasive characterization of the mechanics of musculoskeletal tissues is an ongoing research focus in biomechanics. Often, these methods use the speed of shear wave propagation to characterize tissue mechanics (e.g., shear wave elastography and shear wave tensiometry). The primary purpose of this systematic review was to identify, compare, and contrast current methods for exciting and measuring shear wave propagation in musculoskeletal tissues. We conducted searches in the Web of Science, PubMed, and Scopus databases for studies published from January 1, 1900, to May 1, 2020. These searches targeted both shear wave excitation using acoustic pushes and mechanical taps, and shear wave speed measurement using ultrasound, magnetic resonance imaging, accelerometers, and laser Doppler vibrometers. Two reviewers independently screened and reviewed the articles, identifying 524 articles that met our search criteria. Regarding shear wave excitation, we found that acoustic pushes are useful for exciting shear waves through the thickness of the tissue of interest, and mechanical taps are useful for exciting shear waves in wearable applications. Regarding shear wave speed measurement, we found that ultrasound is used most broadly to measure shear waves due to its ability to study regional differences and target specific tissues of interest. The strengths of magnetic resonance imaging, accelerometers, and laser Doppler vibrometers make them advantageous to measure shear wave speeds for high-resolution shear wave imaging, wearable measurements, and non-contact ex vivo measurements, respectively. The advantages that each method offers for exciting and measuring shear waves indicate that a variety of systems can be assembled using currently available technologies to determine musculoskeletal tissue material behavior across a range of innovative applications.

Sonoelastography to Assess Muscular Stiffness Among Older Adults and its Use for the Diagnosis of Sarcopenia: A Systematic Review

Changes in muscle stiffness have been reported with sarcopenia. Sonoelastography is an accessible and non-radiating imaging technique allowing quantification of elastic properties of tissue. We performed a systematic review of the literature to investigate whether sonoelastography can be a reliable method to assess sarcopenia in older patients. We searched Medline, Google Scholar, Scopus, SpringerLink and Science direct from January 1, 1990 to April 1, 2020. Three independent review authors assessed trial eligibility, extracted the data, and assessed risk of bias. We intended to learn which types of elastography have been tested, if such measures are repeatable, and if they have been compared to the currently accepted diagnostic method. Ten studies met the inclusion criteria. Most followed a cross-sectional design with young and older adult subgroups. The gastrocnemius, rectus femoris, and vastus intermedius appeared most frequently. Nine of the included studies used shear wave elastography and one-strain elastography. The passive elastic constant was significantly greater in sarcopenic versus healthy subjects after passive stretching (124.98 ± 60.82 vs. 46.35 ± 15.85, P = 0.004). However, even in non-sarcopenic patients, the age of the patient was responsible for about 45.5 % of the variance in SWV. Among ten included articles, four reported higher stiffness in the muscles of older adults, two reported lower stiffness, and four found no significant difference. Due to the substantial heterogenicity of actual data, we could not make any conclusions about the potential usefulness of elastography to assess sarcopenia. Further studies are needed, including a larger sample of older patients and using a standardized and reproducible protocol.

Muscle elasticity is different in individuals with diastasis recti abdominis than healthy volunteers

Objective

To determine the value of shear wave elastography (SWE) in assessing abdominal wall muscles, including rectus abdominis (RA), external oblique muscle (EO), internal oblique muscle, and transversus abdominis (TrA) in patients with diastasis recti abdominis (DRA) and healthy controls.

Methods

From October 2018 to December 2019, 36 postpartum DRA patients and 24 nulliparous healthy women were identified. Inter-rectus distance (IRD) measurements were taken by B-mode ultrasound. Shear wave speed (SWS) values were acquired by one operator at ten specific locations. Clinical and ultrasound variables, including demographics, IRD, muscle thickness, and muscle SWS, were compared between the two groups using Student’s t test or Fisher's exact test. Pearson correlation analyses were conducted for the variables of IRD, muscle thickness, and SWS in the 36 DRA patients.

Results

The maximum diameter of recti abdominus separation was located at the umbilicus in DRA patients (4.59 ± 1.14 cm). The SWS value was significantly lower in the RA (p = 0.003) and higher in the TrA muscle (p < 0.001) in DRA patients compared with the age-matched controls. However, SWS in both muscles (RA and TrA) showed a statistically positive correlation with IRD (p < 0.05). In addition, the SWS value in EO statistically decreased in DRA patients compared with the healthy controls (1.65 ± 0.15 vs. 1.79 ± 0.14, p = 0.001).

Conclusions

The application of SWE to abdominal wall muscles in DRA patients is feasible. The correlation between SWS value and IRD in RA should be interpreted with caution.

Using shear wave elasticity in normal terminal ileum of a healthy southwest Chinese population: a pilot study of reference elasticity ranges

Background

Elastography has not been widely applied to the gastrointestinal tract. The bowel wall's normal elasticity values are still unknown and are necessary for studies of gastrointestinal diseases. This study explores the feasibility of using shear wave elastography (SWE) to measure the terminal ileum wall stiffness in healthy subjects and establish the corresponding normal ranges of elasticity values.

Methods

This observational study recruited 139 healthy adult volunteers from April to July 2020. All examinations were performed in the anterior terminal ileum wall. Shear wave velocity (SWV) and Young's modulus (E) values were measured in the midline on longitudinal sections and replicated different operators' obtained data. Also, bowel wall thickness (BWT) and depth were recorded. Subgroups were classified according to the volunteers' gender, age, body mass index (BMI), BWT, and depth. The intra-class correlation coefficient was calculated to analyze inter- and intra-operator consistency, and independent t-tests and one-way analysis of variance were used to explore the differences in variables.

Results

The inter- and intra-operator agreements were good to excellent by different operators and in the replicated measurements (intra-operator consistency: 0.963; inter-operator consistency: 0.842). In all volunteers, the mean SWV was 1.08±0.25 m/s, the mean E value was 3.84±1.84 kPa, and the median BWT was 2 mm. SWV and E did not show significant differences according to gender (P=0.589), age (P=0.738), BMI (P=0.678), depth (P=0.375), or BWT (P=0.410). BWT did not show significant differences according to age (P=0.142), BMI (P=0.863), or depth (P=0.368).

Conclusions

SWE can be used in terminal ileum wall stiffness measurements with good reliability, and the SWE values do not appear to vary significantly according to different physiological factors. The corresponding elasticity ranges of the terminal ileum in normal adults were acquired.

Usability and Pitfalls of Shear-Wave Elastography for Evaluation of Muscle Quality and Its Potential in Assessing Sarcopenia: A Review

Sarcopenia is age-related progressive and generalized loss of skeletal muscle mass and strength. Its prevalence is rising, which poses a burden for society because it increases disability and dependency and therefore raises health care costs. Muscle mass quality, however-an essential part of sarcopenia-is not easily diagnosable yet. Recent interest has risen for ultrasonographic evaluation of muscle. This review introduces muscle elastography as a possible, easy and cheap tool to evaluate qualitative muscle parameters. Basic principles of muscle elastography are described, as well as different elastography techniques and some technical considerations. Furthermore, a proposal for practical guidelines is offered and factors influencing muscle stiffness are highlighted.

Use of Shear Wave Elastography to Quantify Abdominal Wall Muscular Properties in Patients With Incisional Hernia

Shear wave elastography (SWE) is a potential modality that quantitatively measures the elasticity (shear wave speed [SWS]) of musculoskeletal structure. This SWS was bilaterally measured in the rectus abdominis (RA), external oblique (EO) muscle, internal oblique (IO) muscle and transversus abdominis (TrA) using SWE in 28 patients with incisional hernia and 14 healthy controls. The differences in muscle thickness for IO and TrA were significant between the two groups (p < 0.05). The SWS of RA, EO, IO and TrA was significantly higher in the incisional hernia patient group than in the healthy controls (p < 0.05). Significant differences were also observed between the upper and lower points in both groups (p < 0.05). The measurements of SWS help in evaluating the elastic properties of abdominal wall muscles, which could further aid in preparing treatment plans to improve muscle strength.

Use of ultrasound shear wave to measure muscle stiffness in children with cerebral palsy

PURPOSE

Cerebral palsy (CP) is a disorder characterized by an increased muscle stiffness that can be contingent on both neurological and biomechanical factors. The neurological aspects are related to hyper-excitability of the stretch reflex, while the biomechanical factors are related to modifications in muscle structure. We used smart-shear wave elastography (S-SWE) to analyze muscle properties and to compare shear wave speed in soleus muscles of patients affected by CP and typically developing children.

METHODS

We enrolled 21 children (15 males and 6 females; age range 3-16) with spastic hemiplegia CP and 21 healthy children (11 males and 10 females; age range 3-14). Measurements of soleus S-SWE were performed using a Samsung RS80A ultrasound scanner with Prestige equipment (Samsung Medison Co. Ltd., Seoul, Korea), with a convex array transducer (CA1-7; Samsung Medison Co. Ltd., Seoul, Korea). For each CP child clinical assessment included Modified Ashworth Scale (MAS) score.

RESULTS

Children with CP showed greater S-SWE values than the healthy ones (p < 0.001). Our data suggest a significant correlation between the S-SWE values and the MAS scores (Spearman correlation coefficient 0.74; p < 0.001 at Kruskal-Wallis test) in children with CP.

CONCLUSIONS

Measuring muscle properties with SWE, a non-invasive and real-time technique, may integrate the physical exam. SWE may be a reliable clinical tool for diagnosis and longitudinal monitoring of muscle stiffness, as well as particularly suitable for grading and for assessing the response to treatments.

Influencing Factors of 2D Shear Wave Elastography of the Muscle - An Ex Vivo Animal Study

OBJECTIVE

To evaluate measurement confounders on 2D shear wave elastography (2D-SWE) elastography of muscle.

MATERIALS AND METHODS

Ex vivo , porcine muscle was examined with a GE LOGIQ E9 ultrasound machine with a 9 L linear (9 MHz) and C1-6 convex probe (operating at 2.5 or 6 MHz). The influence of different confounders on mean shear wave velocity (SWVmean) was analyzed: probes, pressure applied by probe, muscle orientation, together with the impact of different machine settings such as frequency, placement depth and size of region of interest (ROI). The mean of twelve repeated SWVmean measurements (m/s) and coefficient of variation (CV; standard deviation/mean in %) were assessed for each test configuration.

RESULTS

Reproducibility (CV) and maximum possible tissue depth of the linear probe were inferior to the convex probe. With the linear probe, there was a linear decrease of SWVmean with placement depth from 4.56 m/s to 1.81 m/s. A significant increase of SWVmean (p<0.001) was observed for larger ROI widths (range 3.96 m/s to 6.8 m/s). A change in the machine operation mode ('penetration' instead of 'general') led to a significant increase of SWVmean (p=0.04). SWVmean in the longitudinal direction of muscle was significantly higher than in cross section (p<0.001) (e. g. 4.56 m/s versus 3.42 m/s). An increase of linear probe pressure significantly increased muscle SWVmean from 5.29 m/s to 7.21 m/s (p<0.001).

CONCLUSIONS

2D-SWE of muscle is influenced by a wealth of parameters. Therefore, standardization of measurement is advisable before application in clinical research studies and routine patient assessment.