Ultrasound shear wave elastography in the assessment of passive biceps brachii muscle stiffness: influences of sex and elbow position

Upper extremity soft tissue stiffness measured with shear wave elastography: A between-day reliability study

Background

Imbalances in soft tissue stiffness (STS) of the pectoralis and common wrist extensors (CWEs) can adversely alter upper extremity function. Shear wave elastography (SWE) has the capacity to provide precise, repeatable, objective data on STS. The purpose of this study was to determine the between-day intrarater reliability for the pectoralis and CWE tendon stiffness as measured by SWE.

Methods

STS measured by the shear wave modulus (kilopascals (kPa)) was captured bilaterally on the pectoralis major, pectoralis minor, and CWE tendon using 2D SWE ultrasound imaging (GE Logiq S8, 9 L transducer) on two separate days. Within examiner intraclass correlation coefficients (ICC (3, 3)) with 95% confidence intervals, standard error of the measure, and minimal detectable changes were calculated.

Results

The investigators recruited 10 healthy participants (mean age = 23.50  ±  1.43). Between day intrarater reliability values were obtained for the dominant pectoralis major ICC  =  0.70 (-0.15, -0.93), nondominant pectoralis major ICC  =  0.63 (-0.30, -0.91), dominant pectoralis minor ICC  = 0 .72(-0.04, -0.93), nondominant pectoralis minor ICC  = 0.75(0.08, -0.94), dominant CWE tendon ICC  =  0.75(-0.08, -0.94), and nondominant CWE tendon ICC  =  0.75(-0.12, -0.94).

Discussion

Our data demonstrate acceptable reliability but future studies should include methods that control for variables known to effect STS.

Reliability of Ultrasound Shear Wave Elastography for Evaluating Psoas Major and Quadratus Lumborum Stiffness: Gender and Physical Activity Effects

OBJECTIVE

We aimed to assess the reliability of quantifying psoas major (PM) and quadratus lumborum (QL) stiffness with ultrasound shear wave elastography (SWE), and to explore the effects of gender and physical activity on muscle stiffness.

METHODS

Fifty-two healthy participants (18-32 y) were recruited. To determine reliability, 29 of them underwent repeated SWE measurements of PM and QL stiffness by an operator on the same day. The intra-class correlation coefficients (ICC3,1), standard error of measurement (SEM) and minimal detectable change with 95% confidence interval (MDC95) were calculated. The rest participants underwent a single measurement. Two-way MANCOVA was conducted for the effects of gender and physical activity on muscle stiffness.

RESULTS

The observed reliability for PM (ICC3,1 = 0.89-0.92) and QL (ICC3,1 = 0.79-0.82) were good-to-excellent and good, respectively. The SEM (kPa) was 0.79-1.03 and 1.23-1.28, and the MDC95 (kPa) was 2.20-2.85 and 3.41-3.56 for PM and QL, respectively. After BMI adjustment, both gender (PM: F = 10.15, p = 0.003; QL: F = 18.07, p < 0.001) and activity level (PM: F = 5.90, p = 0.005; QL: F = 6.33, p = 0.004) influenced muscle stiffness. The female and inactive groups exhibited higher stiffness in both muscles.

CONCLUSION

SWE is reliable for quantifying the stiffness of PM and QL. Female and physical inactivity may elevate PM and QL stiffness, underscoring the importance of accounting for these factors in muscle stiffness investigations. Larger prospective studies are needed to further elucidate their effects.

Applications of ultrasound elastography to hand and upper limb disorders

Ultrasound elastography is a recently developed method for accurate measurement of soft tissue stiffness in addition to the clinician's subjective evaluation. The present review briefly describes the ultrasound elastography techniques and outlines clinical applications for tendon, muscle, nerve, skin and other soft tissues of the hand and upper limb. Strain elastography provides a qualitative evaluation of the stiffness, and shear-wave elastography generates quantitative elastograms superimposed on a B-mode image. The stiffness in degenerative tendinopathy and/or tendon injury was significantly lower than in a normal tendon in several studies. Elastography is also a reliable method to evaluate functional muscle activity, compared to conventional surface electromyography. The median nerve is consistently stiffer in patients with carpal tunnel syndrome than in healthy subjects, on whatever ultrasound elastography technique. Elastography distinguishes normal skin from scars and can be used to evaluate scar severity and treatment. Elastography has huge clinical applications in musculoskeletal tissues. Continued development of systems and increased training of clinicians will expand our knowledge of elastography and its clinical applications in the future.

Evaluation of skeletal muscle elasticity using color Doppler shear wave imaging

PURPOSE

This study aimed to (1) assess the precision and reproducibility of color Doppler shear wave imaging (CD SWI) by comparing it with shear wave elastography (SWE) via elasticity phantom measurements, and (2) investigate the potential clinical applications of CD SWI in the upper limb muscles by assessing the reproducibility of skeletal muscle elasticity evaluations.

METHODS

Four elastography phantoms of different stiffness (6.0-7.5 wt%) were used to assess the precision and reproducibility of CD SWI (compared with SWE) at depths. Typical upper limb muscles of 24 men were also assessed for this comparison.

RESULTS

At superficial depths (0-2 cm), the phantom measurements obtained using CD SWI and SWE were similar at all levels of stiffness. Furthermore, both methods were highly reliable, with almost perfect intra- and inter-operator reliabilities. At greater depths (2-4 cm), measurements obtained using both methods were similar at all stiffness levels. Although standard deviations (SDs) of the phantom measurements obtained using both methods at lower stiffness were similar, those at higher stiffness were different. The SD of the CD SWI measurements was < 50% of that of the SWE measurements. However, both methods were highly reliable in the phantom test, with almost perfect intra- and inter-operator reliabilities. The intra- and inter-operator reliabilities of the shear wave velocity measurements for typical muscles of the upper limbs were also substantial in clinical settings.

CONCLUSION

CD SWI is a valid method for measuring elasticity, with precision and reliability as high as those of SWE.

Common Wrist-Extensor Tendon and Pectoralis Muscle Stiffness in Healthy Recreational Tennis Players

CONTEXT

Imbalances in upper-extremity soft tissue stiffness may play a role in the development of shoulder and elbow musculoskeletal injuries in tennis players. Ultrasound shear wave elastography provides quantifiable and specific data regarding muscle stiffness. The purpose of this study was to compare tendon and muscle stiffness in healthy tennis players to nontennis players.

DESIGN

Cross-sectional study.

METHODS

The shear wave modulus, measured in kilopascals, was obtained for the dominant pectoralis major, pectoralis minor, and common wrist-extensor tendon using 2-dimensional shear wave elastography ultrasound imaging (GE Logiq S8, L9 linear transducer). Independent t test was run to compare age, body mass index, and the activity index score between both groups. Within-day intrarater reliability was assessed using a within-examiner intraclass correlation coefficients (ICC [3, 1]) with 95% confidence intervals. A multivariate general linear model was run to compare the mean differences between the tennis and nontennis players for each of the soft tissues.

RESULTS

Twenty-six individuals (13 tennis players and 13 nontennis players) were recruited. Within-day ICCs were very good (ICC > .78 for the pectoralis musculature) and excellent (ICC > .94 for the common wrist extensor). Common extensor tendon stiffness was significantly higher in tennis players compared to nontennis players (mean difference = 114.8 [61.8], confidence interval, -22.8 to 252.5 kPa for the dominant arm [P = .039]). Mean pectoralis major and minor stiffness differences were not significant (P > .214).

CONCLUSIONS

Common wrist-extensor stiffness in healthy recreational tennis players is higher than those who do not play tennis. Therefore, clinicians may need to facilitate a greater soft tissue stiffness response with resistance training when rehabilitating recreational tennis players as compared to those not playing tennis. Additional normative data on a larger sample of recreational tennis players should be collected.

Analysis of the thenar muscles with ultrasound shear wave elastography: Reliability and preliminary findings

INTRODUCTION/AIMS

Ultrasound shear wave elastography (SWE) of the thenar muscles has the potential to provide a simple and noninvasive assessment of the severity of carpal tunnel syndrome (CTS), but its reliability is unknown. The purpose of this study was to assess the intra- and inter-rater reliability of SWE measurements of the elastic modulus of individual thenar muscles, to assess their suitability for clinical application.

METHODS

Fourteen healthy volunteers, seven male and seven female, participated in this study. The elastic modulus of the thenar muscles was measured with SWE, with two independent examiners to assess inter-rater reliability. The first examiner also performed a second measurement after an interval of least 1 day to assess intra-rater reliability. Reliability was evaluated using an intraclass correlation coefficient (ICC) and 95% confidence interval (CI).

RESULTS

For the abductor pollicis brevis (APB) and opponens pollicis (OPP), the CI of ICC in intra-rater reliability was 0.47-0.85 and 0.56-0.88, respectively. The CI of ICC in inter-rater reliability was 0.27-0.78 for the APB and 0.22-0.76 for the OPP. The ICCs of intra- and/or inter-rater reliability of other thenar muscles were less than 0.5.

DISCUSSION

In this study, SWE evaluations of thenar muscles were quite variable in terms of their reliability. A larger study will be needed to determine the source of this variability, improve reliability, and assess the value of SWE in the evaluation of the severity of CTS.

Quantitative assessment of thenar to evaluate hand function after stroke by Bayes discriminant

BACKGROUND

The incidence rate of stroke or cerebrovascular accidents ranks first in China. More than 85% of stroke patients have residual upper limb motor dysfunction, especially hand dysfunction. Normalizing the rehabilitation evaluation process and standard quantitative evaluation method is a complex and key point in rehabilitation therapy. The study aimed to establish a function model based on the Bayes discriminant by measuring the thenar stiffness with shear wave elastography (SWE) to quantitatively evaluate the hand motor function of hemiplegic patients after stroke.

METHODS

This study collected 60 patients diagnosed with hemiplegia after stroke from October 2021 to October 2022. Therapists used the Brunnstrom assessment (BA)scale to divide the patients into the stage. All the patients underwent the measurement of SWE examination of abductor pollicis brevis (APB), opponens pollicis (OP), flexor pollicis long tendon (FPLT), and flexor pollicis brevis (FPB) by two sonographers. The SWE change rate of four parts of the thenar area was calculated prospectively with the non-hemiplegic side as the reference, the function equation was established by the Bayes discriminant method, and the evaluation model was fitted according to the acquired training set data. Lastly, the model was verified by self-validation, cross-validation, and external data validation methods. The classification performance was evaluated regarding the area under the ROC curve (AUC), sensitivity, and specificity.

RESULTS

The median SWE values of the hemiplegic side of patients were lower than those of the non-hemiplegic side. According to the BA stage and SWER of APB, OP, FPLT, and FPB, our study established the Bayes discriminative model and validated it via self-validation and cross-validation methods. Then, the discriminant equation was used to validate 18 patients prospectively, the diagnostic coincidence rate was about 78.8%, and the misjudgment rate was approximately 21.2%. The AUC of the discriminant model for diagnosing BA stage I-VI was 0.928(95% CI: 0.839-1.0),0.858(95% CI: 0.748-0.969),1.0(95% CI: 1.0-1.0), 0.777(95% CI: 0.599-0.954),0.785(95% CI: 0.593-0.977) and 0.985(95% CI: 0.959-1.0), respectively.

CONCLUSION

This Bayes discriminant model built by measuring thenar stiffness was of diagnostic value and can provide an objective basis for evaluating clinical rehabilitation.

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.

Shear Wave Elastography in Patients with Spinal Muscular Atrophy Types 2 and 3

INTRODUCTION

 This study aimed to investigate selective muscle involvement by shear wave elastography (SWE) in patients with spinal muscular atrophy (SMA) types 2 and 3 and to compare SWE values with magnetic resonance imaging (MRI) in demonstrating muscle involvement.

METHODS

 Seventeen patients with SMA types 2 and3 were included in the study. SWE was used to evaluate stiffness of the upper and lower extremities and paraspinal muscles. Involvement of the paraspinal muscles was evaluated using 1.5-T MRI.

RESULTS

 Among the upper extremity muscles, SWE values were the highest for the triceps brachii; however, no significant difference was noted (p = 0.23). In post hoc analysis, a significant difference was observed between triceps brachii and biceps brachii (p = 0.003). Patients with a longer disease duration have the highest SWE values for the triceps brachii (r = 0.67, p = 0.003). Among the lower extremity muscles, SWE values for the iliopsoas were significantly higher than the gluteus maximus (p < 0.001). A positive correlation was found between SWE values and MRI scores of paraspinal muscles (r = 0.49, p = 0.045; r = 0.67, p = 0.003).

CONCLUSION

 This is the first study to report muscle involvement assessed by SWE in patients with SMA types 2 and 3. Our findings are similar to the presence of selective muscle involvement demonstrated in previous studies, and also SWE and MRI values were similar. SWE is an alternative noninvasive practical method that can be used to demonstrate muscle involvement in patients with SMA, to understand the pathogenesis of segmental involvement, and to guide future treatments or to monitor the effectiveness of existing new treatment options.

Shear wave elastography characterizes passive and active mechanical properties of biceps brachii muscle in vivo

Mechanical characterization of individual muscles in their in vivo environment is not well studied. Shear wave elastography (SWE) as a non-invasive technique was shown to be promising in quantifying the local mechanical properties of skeletal muscles. This study aimed to investigate the mechanics of the biceps brachii muscle (BB) derived from SWE in relation to elbow joint position and contraction intensity during isometric contraction. 14 healthy, young subjects participated in the study and five different joint positions (60°-180° elbow angle) were investigated. Shear elastic modulus and surface electromyography (sEMG) of the BB and elbow torque were measured simultaneously, both in passive (i.e., resting) and active states during slow, sub-maximal isometric ramp contractions up to 25%, 50%, and 75% of the maximum voluntary contraction. At passive state, the shear elastic modulus of the BB increased with increasing elbow angle (p < 0.001). Maximum elbow flexion torque was produced at 60° and it decreased with increasing elbow angle (p = 0.001). During sub-maximal contractions, both elbow angle (p < 0.001) and contraction intensity (p < 0.001) had significant effects on the shear elastic modulus but only contraction intensity (p < 0.001) affected sEMG amplitude of the BB. Although torque was decreased at extended elbow positions (150°, 180°), higher active shear elastic modulus of BB muscle was found compared to flexed positions (60°, 90°). Linear regression of the BB sEMG amplitude over elbow torque showed good agreement for all joint positions (R² between 0.69 and 0.89) while the linear agreement between shear elastic modulus of BB and elbow torque differed between flexed (R² = 0.70 at 60° and R² = 0.79 at 90°) and extended positions (with the lowest R² = 0.57 at 150°). We conclude that using SWE, we can detect length-dependent mechanical changes of BB both in passive and active states. More importantly, SWE can be used to characterize active muscle properties in vivo. The present findings have critical importance for developing muscle stiffness as a measure of individual muscle force to validate muscle models and using SWE in clinical diagnostics.

Variability of Biceps Muscle Stiffness Measured Using Shear Wave Elastography at Different Anatomical Locations With Different Ultrasound Machines

Shear wave elastography is an emerging diagnostic tool used to assess for changes in the stiffness of muscle. Each region of the muscle may have a different stiffness; therefore, the anatomical region should be carefully selected. Machine vendors each have unique methods for calculating the returned stiffness values and, consequently, a high level of agreement in measurement between machines (quantified using the intraclass correlation coefficient [ICC] and Bland-Altman analysis) will allow research findings to be translated to the clinic. This study assessed three locations within the biceps muscle (50% and 75% of the distance between the acromioclavicular joint and antecubital fossa, and superior to distal myotendinous junction [MTJ]) of 32 healthy volunteers with two different machines, the Canon Aplio i600 and SuperSonic Imagine Aixplorer (SSI), to compare the reported shear wave velocities and the variability by coefficient of variation (CV) and ICC. There was no difference in the CV between machines, but a significant difference in the CV at muscle regions, with the 75% location having a 40.2% reduction in CV. The 75% location had the highest ICC values with good posterior mean ICCs of 0.84 on the Canon and 0.83 on the SSI. The 50% and MTJ locations had poor ICC values. The 75% location provided the lowest CV and highest ICC and should be used for future stiffness assessments.

Spastic muscle stiffness evaluated using ultrasound elastography and evoked electromyogram in patients following severe traumatic brain injury: an observational study

OBJECTIVE

To determine the relationship between muscle stiffness assessed using ultrasound shear wave elastography, spinal motor neuron excitability assessed using the F wave, and clinical findings of spasticity in patients with spastic muscle overactivity following severe traumatic brain injury.

METHODS

This study enrolled 17 inpatients with severe traumatic brain injury and 20 healthy volunteers. Biceps brachii muscle stiffness was then evaluated using ultrasound shear wave speed. Spinal motor neuron excitability was evaluated using the F/M ratio recorded from abductor pollicis brevis muscle. Clinical parameters, such as the modified Ashworth scale and modified Tardieu scale, were assessed in the patient with traumatic brain injury.

RESULTS

The patients with traumatic brain injury group had a significantly higher shear wave speed and F/M ratio compared with the healthy group. A higher shear wave speed was correlated with higher clinical spastic severity in patients with traumatic brain injury. The F/M ratio was not significantly correlated with clinical spastic severity.

CONCLUSION

Ultrasound shear wave elastography might be helpful for assessing muscle stiffness in patients with spastic muscle overactivity following severe traumatic brain injury. Further studies comprising larger cohorts are warranted.

Changes in Muscle Shear Modulus and Urinary Titin N-Terminal Fragment after Eccentric Exercise

This study aimed to investigate the relationship between the muscle shear modulus of the biceps brachii, urinary titin N-terminal fragment (UTF), and other damage markers after eccentric exercise. Seventeen healthy males performed five sets of ten eccentric exercises with dumbbells weighing 50% of the maximum voluntary contraction (MVC) at the elbow joint. Muscle shear modulus with range of interest set to only biceps brachii muscle measured by ultrasound shear wave elastography, UTF, MVC, range of motion (ROM), and soreness (SOR) were recorded before, immediately after, and 1, 24, 48, 72, 96, and 168 h after eccentric exercise. Each marker changed in a time course pattern, as found in previous studies. The peak shear modulus showed a moderate negative correlation with peak MVC (r = -0.531, P < 0.05) and a strong positive correlation with peak UTF (r = 0.707, P < 0.01). Our study results revealed a significant relationship between muscle strength, shear modulus measured by ultrasound SWE, and titin measured by UTF, as a non-invasive damage marker after eccentric exercise to track changes in EIMD.

Ultrasound and shear-wave elastography characteristics of the iliocapsularis muscle in pincer-type femoroacetabular impingement

BACKGROUND

The iliocapsularis muscle is a structure of the anterior hip, which may play a key role in stabilizing the hip joint, but to our knowledge no studies exist describing ultrasound (US) and shear-wave characteristics of this muscle.

OBJECTIVES

To investigate the anatomic dimensions and elasticity of the iliocapsularis muscle in patients with pincer-type femoroacetabular impingement (FAI) and normal hips using gray-scale US and shear-wave elastography (SWE).

DESIGN

Case-control study.

SETTING

Sports medicine and ultrasound department within a tertiary hospital.

PARTICIPANTS

Thirty-three patients (33 hips) with pincer-type FAI and 37 healthy volunteers (37 hips).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

US parameters (anteroposterior diameter, transverse diameter and circumference) of the iliocapsularis muscle in patients with pincer-type FAI and volunteers. Shear-wave velocity and Young's modulus of the iliocapsularis muscle in patients with pincer-type FAI and volunteers in both neutral and external rotation positions.

RESULTS

Significant differences were not observed in the anatomic dimensions of the iliocapsularis muscle between patients with pincer-type FAI and volunteers. The iliocapsularis muscle in patients with pincer-type FAI had significantly lower shear-wave velocity and Young's modulus than the volunteers (p < .05). The cutoff value of the maximum velocity in the external rotation position was 3.35 m/s, which separated pincer-type FAI patients from volunteers and revealed the highest accuracy with sensitivity, specificity, and accuracy of 78.8%, 48.6%, and 64.3%, respectively.

CONCLUSION

The anatomic dimensions of the iliocapsularis muscle in pincer-type FAI patients and volunteers were similar; however, iliocapsularis stiffness in patients with pincer-type FAI was significantly lower than that of the volunteers. SWE can demonstrate altered muscle stiffness of the iliocapsularis muscle in pincer-type FAI patients, which might be used to help make clinical decisions.

Differences in Medial and Lateral Gastrocnemius Stiffness after Exercise-Induced Muscle Fatigue

Muscles are affected at the cellular level by exercised-induced fatigue, inducing changes in their stiffness. Examining muscle stiffness can improve the knowledge of various pathologic conditions, such as pain and injury. The objective of this study was to examine the stiffness of the medial gastrocnemius (MG) muscle and the lateral gastrocnemius (LG) muscle to determine the changes in stiffness, and to assess the differences in the stiffness between the MG and the LG, as affected by muscle fatigue measured using shear wave elastography (SWE) and a MyotonPRO after inducing muscle fatigue. A total of 35 healthy young adults participated in the study. The stiffness of the MG and the LG were assessed before and after a muscle fatigue protocol (MFP), which included three sets of 50 eccentric contractions of the calf muscles of the dominant leg, at rest, and at maximum voluntary contraction (MVC). The measurements were taken with SWE and the MyotonPRO simultaneously. Compared to baseline, the resting stiffness of the MG and the LG significantly increased immediately, 24 h, and 48 h after muscle fatigue (p < 0.05); however, during MVC, the stiffness of the MG decreased (p < 0.05) and that of the LG showed no change (p > 0.05). When the stiffness of the MG and the LG were compared before and after the MFP, changes in the stiffness of the MG were significantly greater than those in the LG (p < 0.05). This signifies that the MG was more affected by the exercise-induced muscle fatigue than was the LG. The assessment of musculoskeletal tissue and its characteristics, before and after eccentric exercise, is crucial in the prevention of overuse injuries associated with repeated exposure to both low and high levels of force.

Inter-operator and inter-device reproducibility of shear wave elastography in healthy muscle tissues

Purpose

The study aimed to assess whether the more limiting factor in reproducibility of shear wave elastography (SWE) would be the operator dependency or the incompatibility of different ultrasound (US) devices. The interrater agreement with less experienced operators was studied.

Methods

A total of 24 healthy volunteers participated in the study (18 females, 6 males; range of age 27–55 years). SWE of biceps brachii (BB) and tibialis anterior (TA) muscles was performed on both sides from all participants in both longitudinal and transverse orientation of the transducer in respect to muscle fibers. Two operators repeated the SWE with two different US devices from different manufacturers (scanners 1 and 2).

Results

Intraclass correlation coefficient between the two operators was 0.91 (CI 0.88–0.93) for scanner 1 and 0.81 (CI 0.74–0.86) for scanner 2, respectively. Instead, there were significant differences in the SWE measurements between the two scanners, emphasizing in transverse orientation of the transducer. In the transverse transducer orientation, the mean shear wave velocity (SWV) in TA was 1.45 m/s (standard deviation [SD] ± 0.35 m/s) with scanner 1 and 2.35 m/s (SD ± 0.83 m/s) with scanner 2 (p < 0.001). In BB, the mean transverse SWV was 1.49 m/s (SD ± 0.35 m/s) with scanner 1 and 2.29 m/s (SD ± 0.63 m/s) with scanner 2 (p < 0.001). In longitudinal transducer orientation, the mean SWV in TA was 3.00 m/s (SD ± 0.73 m/s) with scanner 1 and 3.26 m/s (SD ± 0.42 m/s) with scanner 2 (p = 0.050). In BB, the mean longitudinal SWV was 3.60 m/s (SD ± 0.77 m/s) with scanner 1 and 3.96 m/s (SD ± 0.62 m/s) with scanner 2 (p = 0.019). The presented mean values were obtained by operator 1, there were no significant differences in the SWE measurements performed by the two operators.

Conclusion

The results implicate that the reproducibility of the SWE measurements depends rather on the used US device than on the operator. It is recommendable that clinics collect reference values with their own US device and consider threshold values presented in previous studies only directional.

Quantifying the stiffness of lumbar erector spinae during different positions among participants with chronic low back pain

Objective

The purposes of this study were to (1) detect the intra- and inter-reliabilities of the lumbar erector spinae stiffness by MyotonPRO among participants with chronic lower back pain (CLBP); (2) compare the muscle stiffness between pain and non-pain sides during different positions; (3) explore the correlation between intensity of pain and muscle stiffness.

Design

Twenty participants with CLBP were recruited and the stiffness measurements were carried out by two experienced physiotherapists (operators Ⅰ and Ⅱ). Each participant was evaluated by the operatorⅠ in different postures (static prone and sitting). After a 5-day interval, the same participant was reassessed by the operatorⅠ in the static prone posture. For the inter-rater reliability test, each participant was quantified by both operators once, with 30 minutes between the measurements on the same day. The intensity of pain was evaluated using a 0–10 visual analog scale (VAS).

Results

The intra- and inter-rater reliabilities were excellent (ICC = 0.88–0.99). The MDC values ranged from 25.03 to 86.26 N/m. Examples of Bland-Altman plots showed good agreement. The erector spinae stiffness on the painful sides was higher with a marked increase in the sitting position (P < .05) when compared with the non-painful side. However, there was no significant difference in the prone position (P > .05). The intensity of pain among adults with CLBP was not associated with muscle stiffness of the lumbar erector spinae muscle.

Conclusions

Our findings indicated that the MyotonPRO is a feasible device in quantifying the stiffness of the lumbar erector spinae muscle in patients with CLBP. Meanwhile, the erector spinae stiffness on the painful sides was higher in the sitting when compared with the non-painful side.

Classifying Muscle States with One-Dimensional Radio-Frequency Signals from Single Element Ultrasound Transducers

The reliable assessment of muscle states, such as contracted muscles vs. non-contracted muscles or relaxed muscles vs. fatigue muscles, is crucial in many sports and rehabilitation scenarios, such as the assessment of therapeutic measures. The goal of this work was to deploy machine learning (ML) models based on one-dimensional (1-D) sonomyography (SMG) signals to facilitate low-cost and wearable ultrasound devices. One-dimensional SMG is a non-invasive technique using 1-D ultrasound radio-frequency signals to measure muscle states and has the advantage of being able to acquire information from deep soft tissue layers. To mimic real-life scenarios, we did not emphasize the acquisition of particularly distinct signals. The ML models exploited muscle contraction signals of eight volunteers and muscle fatigue signals of 21 volunteers. We evaluated them with different schemes on a variety of data types, such as unprocessed or processed raw signals and found that comparatively simple ML models, such as Support Vector Machines or Logistic Regression, yielded the best performance w.r.t. accuracy and evaluation time. We conclude that our framework for muscle contraction and muscle fatigue classifications is very well-suited to facilitate low-cost and wearable devices based on ML models using 1-D SMG.

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.

An exploratory study of two-dimensional shear-wave elastography in the diagnosis of acute compartment syndrome

Background

Two-dimensional shear-wave elastography (2D-SWE) is an ultrasound elastography technique that uses shear waves to quantitatively measure tissue stiffness and it has recently been developed as a safe, real-time, and noninvasive imaging technique. The purpose of this study was to investigate the value of 2D-SWE in the diagnosis and treatment of acute compartment syndrome (ACS).

Methods

2D-SWE was used to measure the elasticity values of the main muscles in the superficial compartments of the calf in 212 healthy volunteers, and the difference in the muscle elasticity values between different gender and age groups were analyzed. Nine patients with clinical suspicion of ACS were included in this study and 2D-SWE was used to measure the elasticity values of the muscles on the affected and unaffected sides, and a comparative analysis was performed.

Results

The mean elasticity values of the tibialis anterior (TA), peroneus longus (PL), and gastrocnemius medialis (GA) muscles in the relaxed state of the 212 healthy volunteers were 25.4 ± 3.2 kPa, 15.7 ± 1.5 kPa, and 12.1 ± 2.1 kPa, respectively. No statistically significant differences was observed in the elasticity values of the same muscle under the state of relaxation in different gender and age groups (p > 0.05). A statistically significant difference in the elasticity values of the muscle between the affected and unaffected sides in the fasciotomy group (p < 0.05, n = 5) was observed. In contrast, no difference in the elasticity values of the muscle between the affected and unaffected sides in the conservative group (p > 0.05, n = 4) was observed. There was a statistically significant difference in the elasticity values of the muscle on the affected side in the two treatment groups (p < 0.05).

Conclusions

When the ACS occurs, the muscle elasticity of the affected limb increases significantly. 2D-SWE is expected to be a new noninvasive technique for the assessment of ACS and may provide a potential basis for clinical diagnosis and treatment.

Effect of gender, muscle type and skinfold thickness on myometric parameters in young people

Background

The aim of the study was to compare the mechanical properties of three human skeletal muscles: biceps brachii (BB), rectus femoris (RF), and tibialis anterior (TA) at rest measured by myoton device in males (n = 16, mean age 21.2 ± 0.6 years) and females (n = 16; 21.2 ± 0.9 years) and to investigate the influence of skin and subcutaneous tissue thickness (skinfold thickness, SFT) and gender on myometric parameters of the three skeletal muscles.

Methods

We measured the following mechanical and viscoelastic muscle properties using MyotonPRO^®: frequency (F [Hz]), decrement (D [log]), stiffness (S [N/m]), relaxation time (R [ms]) and creepability (C [De]). The values of SFT for all selected muscles were assessed by caliper. A mixed-design analysis of variance with gender as between subject comparison was used for assessing the differences between gender and muscles in SFT and each of the myometric parameters separately (F, D, S, R and C). Pearson correlation coefficient or Spearman’s rank correlation coefficient between SFT and myometric parameters was conducted for males, females and males and females together. The level of statistical significance was set at α ≤ 0.05 with Bonferroni correction for multiple comparisons.

Results

The SFT over the RF, TA, and BB muscles in women was statistically significantly larger compared with that of males. In females and males, the SFT over the RF was larger than over the TA and BB, and the SFT over the TA was larger compared with over the BB. The values of F and S recorded for the TA muscle were the highest among the three muscles, while D, C, and R were lowest in TA but highest in the RF muscle in men and women. The values of F and S were smaller in females than in males. Gender comparison of D, C, and R values showed that only D for the RF was significantly lower in females than in males, and C for the RF and TA was significantly larger in females than in males. Some correlation between SFT and myometric parameters were different between males and females. For example, there was a significant, negative correlation between SFT and F for all muscles in females, and a significant, positive correlation between these parameters for BB and TA (not for RF) in males. For pooled data (males and females together), a negative significant correlation between SFT and F was observed for RF and TA (not significant for BB muscle).

Discussion

It is concluded that the TA compared with the BB and RF has significantly greater F and S but the smallest D and C and the shortest R. Gender and muscle differences in the SFT may affect the measurements of muscle properties using MyotonPRO^®. The relationship between SFT and myometric parameters is different in males and females in the RF, TA, and BB muscles. Therefore, the myometric data should be analyzed in males and females separately.

Characteristics of the Passive Muscle Stiffness of the Vastus Lateralis: A Feasibility Study to Assess Muscle Fibrosis

Skeletal muscle fibrosis occurs with aging and has been suggested to impair muscle performance, thereby decreasing quality of life. Recently, muscle stiffness, a surrogate measure of muscle fibrosis, was noninvasively quantified as the shear modulus using ultrasound shear wave elastography (SWE) in humans. We aimed to investigate thigh muscle stiffness in females and males, respectively, across a broad range of ages by using SWE. Eighty-six community-dwelling Japanese people who were aged 30 to 79 years and did not regularly exercise participated in this study. The vastus lateralis (VL) shear modulus was measured at three different knee joint angles: full extension, 90° of flexion, and full flexion. There were no significant main effects of sex or age on the VL shear modulus in full extension or 90° of flexion of the knee. However, the VL shear modulus in knee full flexion was significantly smaller in females than in males and increased with age from 47.9 years. The results suggest that the accelerated increase in VL stiffness that occurs after an individual passes their late 40s may be an important therapeutic target for developing effective treatments and programs that preserve and improve quality of life.

The Utility of Shear-Wave Elastography in the Evaluation of Myositis

Changes in muscle elasticity are expected in patients with untreated myositis. The purpose of this study was to define the accuracy of shear-wave elastography (SWE) in diagnosing myositis. This case control study included 21 patients (mean age, 49.4 y; 12 women) with myositis who underwent SWE, magnetic resonance imaging (MRI) and biopsy of the involved muscle group. SWE was performed accordingly in a control group (n = 24; mean age, 51.2 y; 8 women). Blood tests consisted of creatine kinase (CK) and aldolase. Two operators performed SWE in longitudinal and transverse planes of muscular fibers, quantifying the mean shear-wave velocity (SWV) and the pattern of stiffness. On MRI, short-TI inversion recovery (STIR) signal hyperintensity and T1 contrast enhancement of muscle was considered diagnostic for myositis. The patient group suffered from different types of myositis (nine patients with polymyositis, eight with dermatomyositis and four with other types of myositis). Blood tests showed significantly increased CK and aldolase values in patients with myositis (p < 0.001 and p < 0.0001). MRI showed a sensitivity of 0.95. In the patient group, the mean SWVs of longitudinal and transverse measurements were 2.8 ± 1.4 m/s and 3.1 ± 1.2 m/s, respectively. In the control group, SWVs were 2.3 ± 0.5 m/s and 2.4 ± 0.5 m/s, respectively. The difference between transverse measurements was significant (p = 0.02). Increased heterogeneity as a marker for myositis in transverse SWE showed a sensitivity of 0.8, specificity of 0.79, positive predictive value (PPV) of 0.76 and negative predictive value (NPV) of 0.82. Inter-observer difference was very low (κ = 0.92). Increased heterogeneity in both planes compared with histologic results showed a sensitivity of 0.56, specificity of 0.93, PPV of 0.91 and NPV of 0.62. Spearman correlation between CK <1000 U/L and SWE was 0.54. In conclusion, transverse orientation SWE may serve as an imaging biomarker for the diagnosis of myositis through the display of a heterogeneous pattern and increased absolute SWV values of inflamed muscles.

Ultrasound Elastographic Measurement of Rigor Mortis in an Animal Model: A Feasibility Study for Improved Time-of-Death Estimates in Forensic Investigations

OBJECTIVE. The purpose of our study was to assess the feasibility of 2D shear wave ultrasound elastography to quantitatively measure changes of rigor mortis. SUBJECTS AND METHODS. Muscle stiffness of two live pigs and nine sacrificed pigs was measured in kilopascals using ultrasound elastography. The nine sacrificed pigs were divided into three groups of three pigs each and placed in one of three environments at 90°F (32°C), 70°F (21°C), or 34°F (1°C). Ultrasound elastography of five muscles was performed at 1- to 2-hour intervals for up to 50 hours postmortem. For each pig and muscle location, the time to start, peak intensity, duration of peak, and time to decline of rigor mortis were identified from the graphs of muscle stiffness values over time. These outcome variables were then compared across ambient temperature, body weight, and age groups using the Wilcoxon rank sum test. RESULTS. Postmortem measurements show a rise, peak, and decline of muscle stiffness after death. Rigor mortis was highly significantly affected by ambient temperature (p < .001), was significantly affected by body weight (p = .04), and was not significantly affected by animal age or muscle location (facial vs truncal vs limb) (p > .50). Peak intensity of rigor mortis developed more quickly but attained lower levels of muscle stiffness at 90°F (80-100 kPa) compared with 70°F and 34°F (280-300 kPa) (p < .001). The duration of peak rigor mortis and the time to decline of rigor mortis were significantly longer for the lower temperatures (p < .001). CONCLUSION. Two-dimensional shear wave ultrasound elastography can quantifi-ably measure the trajectory of rigor mortis in an animal model. This new approach may have direct implications for human forensic investigations.

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.

Application of ultrasound elastography in the evaluation of muscle strength in a healthy population

Background

To investigate the validity of shear wave elastography (SWE) for the evaluation of muscle strength compared with isokinetic muscle testing, and to assess the influence of demographic factors such as height, weight, and body mass index (BMI) on the shear wave velocity (SWV).

Methods

Sixty healthy volunteers were consecutively enrolled. SWE was used to measure the SWV of the right quadriceps femoris in a relaxed position, in a tensive position, and under loads of 1 and 2 kg. Muscle strength parameters including peak torque (PT), PT to body weight ratio (PT/BW), and total work (TW) were evaluated using isokinetic muscle testing. The SWV of the rectus femoris in different positions were compared using the Friedman test and the Kruskal-Wallis test, and the SWV and muscle strength parameters were compared between different genders and age groups using the Mann-Whitney U test. Additionally, Spearman's correlation coefficient was used to evaluate the correlation between SWV and muscle strength, as well as the possible effects of height, weight, and BMI on SWV.

Results

As the load increased, the SWV of the rectus femoris increased (P<0.001). In the relaxed position, there was no significant correlation between the SWV and the results of isokinetic muscle testing. With increasing load, the SWV and the results of isokinetic muscle testing were not significantly correlated (r=-0.256--0.392, P<0.05). In the 1 kg load position, height and weight were not significantly correlated with SWV (r=-0.261--0.393, P<0.05). In the relaxed position, there were no significant differences in the maximum, minimum, or mean SWV of the rectus femoris between different genders and age groups (P>0.05). However, under a 1 kg load, the maximum, minimum, and mean SWV of the females in this study were significantly higher than those of the males (4.49±0.60 vs. 3.98±0.68 m/s; 2.55±0.61 vs. 2.20±0.63 m/s; and 3.51±0.60 vs. 3.06±0.58 m/s; P=0.003, 0.028, and 0.004, respectively). Furthermore, there were significant differences in the maximum and mean velocities between the groups aged 20-34 and 35-60 years (4.11±0.62 vs. 4.47±0.70 m/s; 3.17±0.53 vs. 3.52±0.69 m/s; P=0.045 and 0.044, respectively).

Conclusions

Ultrasound elastography (UE) shows potential for the measurement of muscle strength. The SWV of muscles demonstrate an increasing trend with the increase of impedance. Additionally, age and gender have a significant effect on SWV, while the effects of height, weight, and BMI require further investigation.

High school male basketball athletes exhibit greater hamstring muscle stiffness than females as assessed with shear wave elastography

OBJECTIVE

The purpose of this study was to characterize lower extremity passive muscle stiffness in a young, healthy, athletic population. It was hypothesized that males would exhibit greater stiffness than females and that hamstring stiffness would increase with increased passive hamstring stretch.

METHODS

Male (n = 52, age 16.0 ± 1.3 years, height 180.3 ± 7.9 cm, weight 73.1 ± 11.8 kg) and female (n = 89, age 15.6 ± 1.3 years, height 169.7 ± 8.1 cm, weight 65.2 ± 13.2 kg) high school basketball athletes were recruited for this study. Shear wave elastography (SWE) was used to measure shear wave velocity (m/s) of the biceps femoris muscle at three leg positions (40%, 60%, and 80%) of the maximum passive 90-90 straight-leg raise position for each leg. Hamstring stiffness (kPa) was quantified from the SWE elastogram using custom processing software.

RESULTS

Hamstring stiffness was significantly greater for males than females at every position on both the dominant and non-dominant limbs (p < 0.05). Hamstring stiffness was greater on the non-dominant limb than the dominant for females at the 40% position. Stiffness at 60% was greater than stiffness at 40% for males on both the dominant and non-dominant limbs. However, stiffness at 60% was greater than stiffness at 80% on the male non-dominant limb. Females demonstrated higher stiffness at 40% than both 60% and 80% for the dominant and non-dominant limbs.

CONCLUSION

Healthy male basketball players had higher hamstring muscle stiffness than female players. Future studies may investigate what factors contribute to the large variability observed in muscle stiffness, resulting in mixed results on the effects of leg dominance and stretching positions.

In vivo assessment of material properties of muscles and connective tissues around the knee joint based on shear wave elastography

Previous studies on knee biomechanics have mainly focused on the joint structure itself, largely neglecting the material properties of the muscles and connective tissues around the knee joint. Therefore, this study was purposed to conduct a systematic in vivo examination of the material properties of muscles, tendons, and ligaments, and investigated the respective influences of gender and age on the material properties. The participants were 50 healthy males and females within the following four age groups: 21-30 years, 31-40 years, 41-50 years, and above 51 years. The Young's moduli of the muscles, tendons, and ligaments around the knee joint were measured by shear wave elastography (SWE). Analysis of the Young's modulus results showed that excellent repeatability could be achieved by using SWE. For muscles, the intraclass correlation coefficient (ICC) and 95% confidence interval (CI) ranged between 0.952 and 0.987, and 0.923 and 0.992, respectively. The ICC ranged from 0.920 to 0.941, and the 95% CI was between 0.872 and 0.969 for tendons and ligaments. Additionally, the Young's moduli of the muscles, tendons, and ligaments of males were greater than those of females. With the exception for medial patellar retinaculum (MPR), the Young's moduli of other observed tissues decreased with age for both males and females, indicating that age has a significant impact on the Young's moduli of muscles, tendons, and ligaments. Hence, SWE is a reliable and repeatable technique that can be used to assess the Young's moduli of the muscles, tendons, and ligaments around the knee joint. Furthermore, gender and age affects the material properties. The results of this study provide an in vivo database of the material properties of muscles and connective tissues, and thus may prove useful for the prevention and treatment of knee joint injuries and diseases.

Shear-wave elastography for assessment of trapezius muscle stiffness: Reliability and association with low-level muscle activity

Purpose

Shear-wave elastography has been recognized a useful tool for quantifying muscle stiffness, commonly reported as shear modulus, however the reports on reliability are often limited to test-retest correlations. In this study, we explored the reliability of shear-wave elastography for assessment of the trapezius muscle stiffness and its relationship with low-level muscle activity.

Methods

Twenty participants were included in a two-session experiment. Measurements of shear modulus and muscle activity were performed at rest and during low-level activity, induced by shoulder abduction without additional external resistance.

Results

Good to excellent intra-session repeatability (ICC > 0.80) and moderate inter-rater and inter-session reproducibility (ICC = 0.66–0.74) were observed. Typical errors were acceptable (7.6% of the mean value) only for intra-session measurements in resting conditions, but not acceptable for all conditions with low-level muscle activity (10.2–16.6% of the mean value). Inverse relationships between shear modulus and muscle activity at 40° and 60° of shoulder abduction (r = -0.53 and -0.57) were observed on a group level. We also found higher shear modulus in males compared to females, for the parallel probe position compared to the perpendicular position (in relation to muscle fiber orientation), and for the dominant side of the body compared to the non-dominant side.

Conclusions

This study showed an inverse relationship between muscle activity in low-level range and shear modulus on a group level, suggesting inherent passive stiffness could account for a larger portion of the variance (compared to muscle activity) in shear modulus when the muscle activity is low. Our results imply that shear-wave elastography can be used in research exploring muscle stiffness, however, caution is needed since only intra-session examination in resting conditions showed acceptable within-participant typical errors. The secondary analyses of the study showed higher shear modulus for males, for the non-dominant side of the body and for the parallel orientation of the ultrasound probe.

Increased neck muscle stiffness in migraine patients with ictal neck pain: A shear wave elastography study

Background

Ictal neck pain is a frequent symptom reported by half of migraine patients. It is unknown if neck pain is caused by peripheral or central mechanisms. Neck muscle stiffness can be investigated with ultrasound shear wave elastography.

Objectives

To determine if migraine patients with ictal neck pain have stiffer neck muscles interictally compared with patients without ictal neck pain and controls.

Methods

This was a cross-sectional study investigating neck muscle stiffness, pressure pain thresholds and neck pain symptoms in 100 migraine patients recruited from a tertiary headache center and 46 controls.

Results

Patients with ictal neck pain had increased mean neck muscle stiffness interictally compared to both migraine patients without ictal neck pain ( p = 0.018) and controls ( p = 0.036). Muscle stiffness was negatively correlated with pressure pain thresholds in the neck in migraine patients with ictal neck pain (r = −0.292, p = 0.042). There were no differences in mean pressure pain thresholds between migraine subgroups.

Conclusions

Migraine patients with ictal neck pain have stiffer neck muscles interictally compared with migraine patients without ictal neck pain and controls measured with ultrasound shear wave elastography. The increased stiffness could be due to local alterations in the neck muscles. Trial registration: clinical-trials.gov, identifier: NCT03626805

Intra-rater reliability and smallest detectable change of compression sonoelastography in quantifying the material properties of the musculoskeletal system

Musculoskeletal conditions can change tissue elasticity. Knowledge of musculoskeletal elasticity could therefore aid clinical diagnosis and management. Sonoelastography is an ultrasound-based system that examines the material properties of tissues, and it may be useful in musculoskeletal practice. Therefore, it is important to establish its clinimetric properties. This study aimed to explore the intra-rater reliability and the smallest detectable changes of sonoelastography in examining musculoskeletal structures. A quantitative reliability design was used to examine 22 healthy participants using a compression sonoelastography system that produces color-coded images. The deltoid, biceps brachii, brachioradialis, rectus femoris, gastrocnemius medius muscles, and Achilles tendon were examined twice at 1-hr intervals to assess the intra-rater reliability. The sonoelastography images were analyzed using the strain index, strain ratio, and color pixels. The intra-rater reliability and the smallest detectable changes of each outcome variable were determined. The intra-class correlation coefficient was used to quantify the repeatability of the measurements, and the smallest detectable changes were calculated to determine clinically important differences above the error of measurement. The intra-rater reliability for the strain index, strain ratio, and color pixel analysis ranged from moderate to excellent (intra-class correlation coefficients: .734-.950, .776-.921, and .754-.990, respectively), with color pixel analysis demonstrating the highest reliability. The smallest detectable changes were determined for all structures, including the Achilles tendon (0.11 for the higher boundary of the strain index, 1.80 for the strain ratio, and 2.90% for red pixels, representing soft tissues). Color pixel analysis may be more reliable for sonoelastography interpretation compared with the strain index and strain ratio. The calculated smallest detectable changes could be used to identify clinically important differences.

Paraffin therapy induces a decrease in the passive stiffness of gastrocnemius muscle belly and Achilles tendon: A randomized controlled trial

BACKGROUND

The purposes of this study were to examine the feasibility of using the MyotonPRO digital palpation device in measuring the passive stiffness of gastrocnemius muscle belly and Achilles tendon; to determine between-days test-retest reliability of MyotonPRO; and to evaluate the acute effect of paraffin therapy on stiffness measurements in healthy participants.

METHODS

It is a randomized controlled trial. Twenty healthy participants (male, n = 10; female, n = 10; total, n = 20) were recruited to evaluate the passive stiffness of gastrocnemius muscle belly and Achilles tendon. Dominant and nondominant legs were randomly divided into an experimental side (20 cases) and a control side (20 cases). The experimental side received 20 minutes of paraffin therapy.

RESULTS

The stiffness of muscle and tendon in the experimental side decreased significantly after paraffin therapy (P < .01), whereas no significant differences in stiffness measurements were found in the control side (P > .05). The passive stiffness of muscle and tendon was positively correlated with the ankle from 30° plantar flexion to10° dorsiflexion for dominant legs. Between-days test-retest reliability in stiffness measurements was high or very high (ICCs were above 0.737).

CONCLUSION

Paraffin therapy induces a decrease in the passive stiffness of gastrocnemius muscle belly and Achilles tendon. Furthermore, the MyotonPRO can reliably determine stiffness measurements.

Assessment of posterior shoulder muscle stiffness related to posterior shoulder tightness in college baseball players using shear wave elastography

BACKGROUND

Limitations of shoulder range of motion (ROM) have been reported to be at high risk for shoulder disorders in baseball players. In this study, we assessed posterior shoulder muscle stiffness using shear wave elastography in baseball players with and without posterior shoulder tightness.

MATERIALS AND METHODS

In total, 21 college baseball players volunteered to participate in this study. Passive ROMs for shoulder abduction and horizontal adduction were measured using a goniometer. Subsequently, we divided all participants into 2 groups based on the differences between bilateral shoulder ROMs: STIFF+ and STIFF- groups. Thickness and elasticity of the posterior and inferior shoulder muscles were assessed using ultrasound.

RESULTS

Shoulder abduction ROM on the throwing side was 114.5° ± 5.3° and 131.3° ± 5.7° in the STIFF+ and STIFF- groups, respectively, which was significantly different between the 2 groups (P = .023). Horizontal adduction ROM on the throwing side was 96.6° ± 4.9° and 110.9° ± 4.8° in the STIFF+ and STIFF- groups, respectively, which was also significantly different between the 2 groups (P = .014). The elasticity of infraspinatus and lower trapezius in the STIFF+ group was significantly greater than that in the STIFF- group (P = .018 and .033, respectively).

DISCUSSION

In this study, we found that the elasticity of infraspinatus and lower trapezius in stiff shoulders was significantly greater than that in nonstiff shoulders, which indicated that the infraspinatus and lower trapezius could be the key muscles in posterior shoulder tightness.

Shear wave elastography potential to characterize spastic muscles in stroke survivors: Literature review

BACKGROUND

Post-stroke spasticity contributes to impairments, disabilities and decline in quality of life. Quantitative measurements of spasticity are needed in order to assess the impact of specific treatments and to choose the more accurate technique for each patient. The aim of this review is to examine the use of shear wave ultrasound elastography as a quantitative tool for monitoring biomechanical muscle properties such as stiffness and to determine whether it is a reliable method to assess spastic muscle in stroke survivors.

METHODS

Studies were sought from Academic Search Complete, CINAHL, PubMed/Medline, Scopus and SportDiscus with the following keywords: shear wave elastography, spasticity, stiffness, elasticity, hardness, stroke, cerebrovascular accident, cerebral vascular event and transient ischaemic attack. Titles and abstracts were screened, and relevant full-text articles were retrieved for further review.

FINDINGS

Of the 76 screened studies, nine captured elastography data of the spastic biceps brachii (n = 6) or the plantar flexors (n = 3) with stroke victims. All consulted studies had a different way of utilizing this technology which was expected considering no guidelines had been developed. Shear wave speed values obtained are compared and discussed with clinical measures. Reliability of the devices is also discussed.

INTERPRETATION

Shear wave ultrasound elastography can provide useful quantitative information on the mechanical properties of the spastic muscles in post-stroke patients. Nevertheless, new studies using common terminology and parameters are needed to develop reliable methods that could help in assessing treatment efficiency.

Ultrasound Shear Wave Elastography to Assess Osteopathic Manipulative Treatment on the Iliocostalis Lumborum Muscle: A Feasibility Study

OBJECTIVES

To investigate the feasibility of ultrasound shear wave elastography (SWE) in assessing iliocostalis lumborum muscle changes after osteopathic manipulative treatment (OMT).

METHODS

Using a linear array ultrasound transducer (4-9 MHz), we prospectively measured the shear wave velocity (SWV) of bilateral iliocostalis lumborum muscles in 20 patients with low back somatic dysfunction and in 9 age-matched healthy volunteers. The SWV was measured in muscle relaxation and contraction in all participants and immediately before and after OMT in patients. We developed a muscle SWV rate [SWV_contraction - SWV_relaxation )/SWV_relaxation ] and an SWV improvement index [(SWV_pre-OMT - SWV_post-OMT )/SWV_pre-OMT ] for quantifying muscle contractibility and changes in muscle stiffness after OMT. Statistical analyses included an unpaired t test to analyze the difference in the muscle SWV between muscle relaxation and contraction and between somatic dysfunction and nonsomatic dysfunction in patients and healthy volunteers, a paired t test to examine the difference in the SWV and SWV rate before and after OMT, the intraclass correlation coefficient to test intraobserver and interobserver reliability, and Spearman rank correlation to analyze the correlation of changes in the SWV with manual osteopathic assessments.

RESULTS

The mean ages of the patients with low back somatic dysfunction and the healthy volunteers were 28 and 26 years, respectively. The muscle SWV significantly differed between somatic dysfunction and nonsomatic dysfunction in patients and healthy volunteers, between muscle relaxation and contraction, and before and after OMT (P < .001). The SWV improvement index moderately correlated with manual osteopathic assessments (r = 0.68). The interobserver and intraobserver reliability for performing SWE was good (intraclass correlation coefficient, >0.8).

CONCLUSIONS

Our results suggest that SWE is feasible for quantifying the change in muscle stiffness and contractibility after OMT.

Shear Waves Reveal Viscoelastic Changes in Skeletal Muscles After Hemispheric Stroke

We investigated alterations in material properties such as elasticity and viscoelasticity of stroke-affected muscles using ultrasound induced shear waves and mechanical models. We used acoustic radiation force to generate shear waves along fascicles of biceps muscles and measured their propagation velocity. The shear wave data were collected in muscles of 13 hemiplegic stroke survivors under passive conditions at 90°, 120°, and 150° elbow flexion angles. In a viscoelastic medium, as opposed to a purely elastic medium, the shear wave propagation velocity depends on the frequency content of the induced wave. Therefore, in addition to the shear wave group velocity (GpV), we also estimated a frequency-dependent phase velocity (PhV). We found significantly higher GpVs and PhVs in stroke-affected muscles ( ). The velocity data were used to estimate shear elasticity and viscosity using an elastic and viscoelastic material models. A pure elastic model showed increased shear elasticity in stroke-affected muscles ( ). The Voigt model estimates of viscoelastic properties were also significantly different between the stroke-impaired and non-impaired muscles. We observed significantly larger model-estimated viscosity values on the stroke-affected side at elbow flexion angles of 120° and 150°. Furthermore, the creep behavior (tissue strain resulting from the application of sudden constant stress) of the model was also different between muscles of the paretic and non-paretic side. We speculate that these changes are associated with the structural disruption of muscles after stroke and may potentially affect force generation from muscle fibers as well as transmission of force to tendons.

Ultrasound Elastography to Assess Botulinum Toxin A Treatment for Post-stroke Spasticity: A Feasibility Study

The aim of the study was to evaluate the feasibility of using ultrasound elastography to assess the effect of botulinum toxin A (BoNT-A) treatment on post-stroke spasticity of the upper limb. In this prospective study, we performed ultrasound elastography (strain imaging and acoustic radiation force impulse-based shear wave elastography) of the spastic biceps brachii muscle in seven patients (five men and two women, mean age: 45y) who underwent BoNT-A injection treatment for post-stroke spasticity of the upper limb. We measured ultrasound elasticity parameters including axial strain ratio (SR) (SR = muscle strain/reference strain), longitudinal SR and shear wave velocity of the biceps muscle immediately before and 17-30 d (mean: 22 d) after BoNT-A injection. Statistical analyses included a two-tailed paired t-test to examine the difference in ultrasound elasticity parameters of bilateral biceps muscles before and after BoNT-A treatment and a Spearman rank correlation coefficient (r_s) to analyze the correlation of ultrasound elasticity parameters to clinical assessment with the Modified Ashworth Scale (MAS) and Tardieu Scale (TS). The difference in ultrasound elasticity parameters before and after BoNT-A treatment was significant (p < 0.05) in the treated spastic muscle. The correlation of ultrasound elasticity parameters with MAS and the angle of catch and range of motion in TS were also significant (r_s = 0.55-0.95, p < 0.05). Our results suggest that ultrasound elastography is feasible in assessment of the effectiveness of BoNT-A treatment for post-stroke spasticity of the upper limb.

Shear Wave Elastography to Assess False Vocal Folds in Healthy Adults: A Feasibility Study

OBJECTIVES

The aim of the study was to investigate the feasibility of using ultrasound shear wave elastography to quantify mechanical properties and movement symmetry of false vocal folds positioned in adduction and abduction.

METHODS

We prospectively measured the shear wave velocity (SWV) within the bilateral false vocal folds in 10 healthy adults using acoustic radiation force impulse imaging. From a transcutaneous approach at the level of thyroid cartilage, 5 SWV measurements were obtained within each side of the false vocal folds twice in adduction and again in abduction for each participant. Configuration-related differences in the SWV within false vocal folds were compared between adduction and abduction, in addition to differences between the right and left false vocal folds and between men and women, by a paired t test. We developed an SWV index [(SWV_greater - SWV_lesser )/SWV_greater ] to assess movement symmetry between the right and left false vocal folds. Intraobserver agreement on repeated measures was examined by the intraclass correlation coefficient.

RESULTS

The 10 participants included 5 men and 5 women. We observed that the SWV within false vocal folds was significantly higher in adduction than in abduction (P < .001). The SWV within false vocal folds in adduction was also significantly higher in women compared to men (P < .001). There was no significant difference in the SWV between the right and left false vocal folds in adduction or in abduction or between men and women in abduction (P > .05). The mean SWV index was 0.05 (range, 0.03-0.07). The intraclass correlation coefficient for intraobserver agreement was 0.89 (P < .001).

CONCLUSIONS

Shear wave elastography seems to be feasible to quantify mechanical properties and evaluate the symmetry of false vocal folds in healthy adults.

Shear wave elastography of parotid glands in pediatric patients with HIV infection

OBJECTIVES

Parotid gland (PG) involvement is common among the patients with HIV infection. Shear wave elastography (SWE) is a noninvasive method used to measure the tissue stiffness of several organs including PG. The aim of this study was to evaluate the tissue stiffness values of PGs of HIV-infected children via SWE and compare the results with the counterparts of healthy subjects.

MATERIALS AND METHODS

This single-center, prospective study included the PG examinations of 23 pediatric HIV patients and 40 healthy children via grayscale ultrasound and SWE. Independent sample T test and Mann-Whitney U test were used in statistical analysis.

RESULTS

Stiffness of both PGs was significantly higher in patients' group when compared with control subjects. In addition, when the patients were separated into two groups according to the appearance of PG on grayscale ultrasound as homogeneous and heterogeneous, stiffness values were increased in the patients with homogeneous parenchymal appearance. No significant difference was achieved in terms of median CD4 and CD8 counts, HIV RNA levels or median duration of illnesses.

CONCLUSIONS

PG examination of HIV-infected children via SWE reveals increased tissue stiffness when compared with healthy subjects. SWE can be used as an ultrasound-assisted noninvasive technique in this manner.

Evaluation of the activities of the medial and lateral heads of quadratus plantae in flexion movements of the lateral four toes using ultrasound real-time tissue elastography

Quadratus plantae (QP), one of the plantar intrinsic foot muscles, assist plantarflexion of the lesser toes. QP has medial and lateral muscle heads with different anatomical structures. The two heads of this muscle may have different roles in foot function. Ultrasound real-time tissue elastography (RTE) measurements have allowed quantitative assessment of deep-layer muscle elasticity. The purpose of this study was to determine the activity of the QP in flexion movements of the lateral four toes using RTE. Thirteen healthy subjects performed maximal voluntary contractions using a hand-held dynamometer with external belt fixation for each toe flexion movement. The elasticity of the muscles were measured using RTE during rest and flexion of each toe. The strain ratio of the muscle to that in an acoustic coupler was calculated as an index of muscle elasticity. Higher strain ratio values imply lower elasticity. The strain ratio of the medial head of QP for second toe flexion (0.10±0.11) was significantly stiffer than at rest (0.34±0.33). The strain ratios of the lateral head of QP for flexion of the second (0.32±0.19), third (0.41±0.37), fourth (0.33±0.26), and fifth (0.45±0.39) toes were significantly stiffer than at rest (1.02±0.68). These results suggest that the medial head of QP has a role in assisting second-toe flexion, and the lateral head has a role in assisting flexion of all four lateral toes.

Quantitative Ultrasound Imaging to Assess the Biceps Brachii Muscle in Chronic Post-Stroke Spasticity: Preliminary Observation

We prospectively investigated the feasibility of using quantitative ultrasound imaging (QUI) to assess the biceps brachii muscle (BBM) in individuals with chronic post-stroke spasticity. To quantify muscle echogenicity and stiffness, we measured QUI parameters (gray-scale pixel value and shear wave velocity [SWV, m/s]) of the BBM in three groups: 16 healthy BBMs; 12 post-stroke, non-spastic BBMs; and 12 post-stroke, spastic BBMs. The QUI results were compared with the Modified Ashworth Scale and Tardieu Scale. A total of 20 SWVs were measured in each BBM, once at elbow in 90° flexion and again at maximally achievable extension using acoustic radiation force impulse imaging. BBM pixel value was measured in gray-scale images captured at 90° elbow flexion using ImageJ software. Statistical analyses included analysis of variance for examining the difference in SWV and pixel values among the three groups; Bonferroni correction for testing the difference in SWV and pixel values in a paired group; t-test for examining the difference in SWV values measured at two elbow angles; and Pearson correlation coefficient for analyzing the correlation of QUI to Modified Ashworth Scale and Tardieu Scale. SWV significantly differed between spastic BBMs and non-spastic or healthy BBMs. For pixel values, each of the three groups significantly differed from the others at elbow 90° flexion. The difference in SWV measured between the two elbow angles was also significant (p <0.01). A strong negative correlation was found between SWV and passive range of motion (R² = -0.88, p <0.0001) in spastic upper limbs. These results suggest that the use of QUI is feasible in quantitative assessment of spastic BBM.