Musculoskeletal Sonoelastography: A Focused Review of its Diagnostic Applications for Evaluating Tendons and Fascia

Ultrasonographic Evaluation of Thickness and Stiffness of Achilles Tendon and Plantar Fascia in Type 2 Diabetics Patients: A Cross-sectional Observation Study

Background

Diabetes mellitus (DM) can contribute to the development of foot ulcers, a known complication of DM with a high financial and social burden. Achilles tendon (AT) and plantar fascia (PF) are well known to play an important role in foot biomechanics. The present study focuses on the alteration in thickness and stiffness of the AT and PF in Type 2 DM patients compared with the normal controls.

Methods

A cross-sectional observational study was conducted with 55 DM patients and 55 healthy volunteers as controls. The thickness of the AT and PF were measured using B-mode ultrasound and stiffness was measured using shear wave elastography. Both the thickness and stiffness in the patient group and controls were compared. The values were also compared with the clinical and demographic profiles of the patients.

Results

DM patients had considerably thicker AT and PF than controls (P < 0.05); mean values of AT thickness for DM patients and controls were 5.66 ± 0.54 mm and 4.61 ± 0.39 mm, respectively, and for PF were 2.53 ± 0.51 mm and 1.97 ± 0.19 mm, respectively. Furthermore, the stiffness of AT and PF was significantly (P < 0.05) lower in DM patients compared to controls, suggestive of softening of AT and PF in Type 2 DM patients. Mean values of shear wave velocity for DM patients and controls in AT were 5.53 ± 0.54 m/s and 7.25 ± 0.61 m/s, respectively, and for PF, 4.53 ± 0.89 m/s and 6.28 ± 0.88 m/s, respectively.

Conclusion

We conclude that there is softening and thickening of the AT and PF in Type 2 DM patients, which can impair foot biomechanics.

Utility of Ultrasound Elastography to Evaluate Poststroke Spasticity and Therapeutic Efficacy: A Narrative Review

Poststroke spasticity (PSS) is a common complication that affects function and daily self-care. Conservative PSS treatments include traditional rehabilitation, botulinum toxin injection, and extracorporeal shock wave therapy. Currently, the Modified Ashworth Scale and Modified Tardieu Scale are widely used tools to clinically evaluate spasticity, but the best tool for PSS assessment remained controversial. Ultrasound elastography (UE), including shear wave and strain image as the emerging method to evaluate soft tissue elasticity, became popular in clinical applications. Spastic biceps and gastrocnemius muscles were reported to be significantly stiffer compared to nonparetic muscles or healthy control using shear wave or strain elastography. More studies investigated the utility, reliability, and validity of UE in patients with PSS, but the contemporary consensus for the utility of UE in the measurement and therapeutic follow-up of PSS remained lacking. Therefore, this narrative review aimed to appraise the literature on the shear wave and strain elastography on PSS and summarize the roles of UE in assessing the therapeutic efficacy of different PSS interventions.

2D-SWE of the Metacarpophalangeal Joint Capsule in Horses

(1) Two-dimensional shear wave elastography (2D-SWE) employs an ultrasound impulse to produce transversely oriented shear waves, which travel through the surrounding tissue according to the stiffness of the tissue itself. The study aimed to assess the reliability of 2D-SWE for evaluating the elastosonographic appearance of the distal attachment of the fetlock joint capsule (DJC) in sound horses and in horses with osteoarthritis (OA) (2). According to a thorough evaluation of metacarpophalangeal joint (MCPJ), adult horses were divided in a sound Group (H) and in OA Group (P). Thereafter, a 2D-SWE of MCPJs was performed. Shear wave velocity (m/sec) and Young’s modulus (kPa) were calculated independently by two operators at each selected ROI. Statistical analysis was performed with R software. (3) Results: 2D-SWE had good–excellent inter-CC and intra-CC in both groups. Differences in m/s and kPa between Groups H and P were found in transverse scans with lower values in Group P. No correlation with age or DJC thickness was found. (4) Conclusions: 2D-SWE was repeatable and reproducible. In Group H, DJC was statistically stiffer than in Group P only in transverse scan. The technique showed poor sensitivity and specificity in differentiating fetlocks affected by OA.

Ultrasound elastography for the evaluation of plantar fasciitis: A systematic review and meta-analysis

PURPOSE

This meta-analysis aimed to investigate the utility of ultrasound (US) elastography in the assessment of plantar fasciitis (PF).

METHODS

We searched PubMed, Embase, and Scopus and systemically reviewed clinical studies that used US elastography for imaging PF. The primary outcome was the comparison of plantar fascia stiffness between healthy controls and patients with PF, quantified using the weighted mean difference (WMD) and standardized mean difference (SMD).

RESULTS

Eleven studies were included in the final systematic review and meta-analysis. In six studies that employed shear wave elastography, patients with PF had a lower shear wave velocity, with a WMD of -1.772 m/s (95 % confidence interval [CI], -2.663 to -0.880) and an SMD of -1.239 m/s (95 % CI, -1.876 to -0.603), compared to those with asymptomatic heels. One study using the strain ratio showed that the WMD and SMD of patients with diseased heels vs healthy controls were -0.400 (95 % CI, -0.850 to 0.050) and -0.442 (95 % CI, -0.946 to 0.062), respectively. In six articles that use the color histogram of strain elastography, less stiffness was consistently reported in the diseased plantar fascia compared with healthy controls.

CONCLUSION

This meta-analysis showed that the plantar fasciae were less stiff in the PF group than in asymptomatic subjects. The diagnostic performance of US elastography (over B-mode) warrants further investigation.

The Association of Achilles Sonoelastography Findings with Disease Activity, Functional Status and Enthesitis Index in Patients with Axial Spondyloarthritis

Background Sonoelastography (SE) is a new ultrasound (US)-based technique able to assess tissue elasticity. Using conventional US, it is sometimes difficult or even impossible to distinguish pathologic tissue because it often presents with the same echogenicity as the surrounding healthy tissue. This study aimed to evaluate SE findings in Achilles tendons of patients with axial spondyloarthritis (axSpA) and to assess how these findings are associated with disease-related parameters.

Material and Methods Sixty-four consecutive patients (37 men, 27 women; mean age 39.7 years; range 20–65 years) with axSpA and 30 sex and age-matched healthy controls were enrolled in the study. Disease activity was evaluated using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), whereas functional capacity was evaluated using the Bath Ankylosing Spondylitis Functional Index (BASFI). Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and the Spondyloarthritis Research Consortium of Canada (SPARCC) enthesitis index were recorded. All participants underwent an SE examination of the Achilles tendon and measurement of the strain index (SI).

Results The mean right and left SI were significantly higher in axSpA patients than in controls (2.96±0.94 vs. 1.90±0.45; p<0.001; 2.95±0.95 vs. 1.92±0.48, p<0.001, respectively). In axSpA patients, both right and left SI were significantly correlated with the BASDAI, BASFI and SPARCC enthesitis indices, but not with ESR or CRP.

Conclusion AxSpA patients had an increased SI compared with healthy subjects and these values were associated with disease activity, functional capacity and the enthesitis index. SE may be a useful tool for the evaluation of Achilles tendons in patients with axSpA.

REAL-TIME strain elastography: Applications in musculoskeletal system

BACKGROUND

Strain or compression sonoelastography (CE) provides a colour-coded elastogram representing tissue elasticity by measuring tissue deformability after repeated probe compression. Elastographic ultrasound (EUS) is a valuable tool for screening diagnosis and follow-up of inflammatory, degenerative, benign and malignant neoplastic pathologies of skin, subcutaneous tissue, muscles, tendons, ligaments, fascia and nerves; help in targeted biopsy; monitor healing tendons after surgery or nerve stiffness changes during physiotherapy.

OBJECTIVES

To assess stiffness of normal tendons, muscles and nerve. To diagnose cellulitis, fasciitis, abscess, tendinopathy, myositis, muscle/tendon rupture/contusion and differentiate between benign and malignant soft tissue tumours. To derive elastic score (ES) and strain ratio (SR) in cases and controls. To correlate B-mode findings with CE.

MATERIALS AND METHODS

A prospective study on 50 healthy subjects between 25 and 30 years and 50 cases of diffuse and focal musculoskeletal pathologies was done using B-mode and CE over 2 years. Statistical analysis of distribution, mean, associations, sensitivity, specificity, area under Receiver Operating Characteristic curve (AUROC) for B-mode, ES, SR combined B-mode/CE and their comparison was done.

RESULTS

Significant association was noted between SR in muscles and tendons with sex. Significant correlation was noted between ES/SR with B-mode. CE and B-mode had 100% and 52.4% sensitivity respectively for diagnosing diffuse pathologies. For differentiating benign and malignant masses sensitivity, specificity, and diagnostic accuracy of B-mode was 71.43%, 86.36% and 82.76%; of SR was 71.43%, 90.91% and 86.21%; of Combined B-mode with CE was 100%, 90.91% and 93.1% respectively. Elastographic pattern had highest diagnostic accuracy and largest AUROC.

CONCLUSION

CE as a screening test had higher diagnostic accuracy, supporting need for standardizing it for clinical use in MSK. EUS being a widely available, fast and affordable modality, can aid follow up of chronic MSK pathologies, response to medication, physiotherapy and surgery and mitigate the need for MRI.

Diagnostic accuracy of examination tests for lateral elbow tendinopathy (LET) - A systematic review

BACKGROUND

Reviews on the diagnostic performance of the examination tests for lateral elbow tendinopathy (LET) based on updated context-specific tools and guidelines are missing.

PURPOSE

To review the diagnostic accuracy of examination tests used in LET.

DESIGN

Systematic review following PRISMA-DTA guidelines.

METHODS

We searched MEDLINE, PubMed, CINAHL, EMBASE, PEDro, ScienceDirect, and Cochrane Library databases. The QUADAS-2 checklist was used to assess the methodological quality of the eligible studies. We included diagnostic studies reporting the accuracy of physical examination tests or imaging modalities used in patients with LET.

RESULTS

Twenty-four studies with 1370 participants were identified reporting the diagnostic performance of Ultrasound Imaging (USI) (18 studies), physical examination tests (2 studies) and Magnetic Resonance Imaging (MRI) (4 studies). Most studies (97%) were assessed with "unclear" or "high risk" of bias. Sonoelastography showed the highest sensitivity (75- 100%) and specificity (85- 96%). Grayscale with or without Doppler USI presented poor to excellent values (sensitivity: 53%-100%, specificity: 42%-90%). MRI performed better in the diagnosis of tendon thickening and enthesopathy (sensitivity and specificity: 81%-100%). The Cozen's test reported high sensitivity (91%) while a grip strength difference of 5%-10% between elbow flexion and extension showed high sensitivity (78%-83%) and specificity (80%-90%).

CONCLUSIONS

Cozen's test and grip strength measurement present high accuracy in the diagnosis of LET but are poorly investigated. USI and MRI provide variable diagnostic accuracy depending on the entities reported and should be recommended with caution when differential diagnosis is necessary. Substantial heterogeneity was found in inclusion criteria, operator/ examiner, mode of application, type of equipment and reference standards across the studies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO ID CRD42020160402.

Reliability and Validity of Ultrasound Elastography for Evaluating Muscle Stiffness in Neurological Populations: A Systematic Review and Meta-Analysis

OBJECTIVE

Ultrasound elastography is an emerging diagnostic technology used to investigate the biomechanical properties of the musculoskeletal system. The purpose of this study was to systematically review the psychometric properties of ultrasound elastography techniques for evaluating muscle stiffness in people with neurological conditions.

METHODS

A systematic search of MEDLINE, EMBASE, CINAHL, and Cochrane Library databases was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Using software, reviewers independently screened citations for inclusion. Peer-reviewed studies that evaluated in vivo muscle stiffness in people with neurological conditions and reported relevant psychometric properties were considered for inclusion. Twenty-one articles were included for final review. Data relevant to measurement technique, site, and neurological condition were extracted. The Consensus-Based Standards for the Selection of Health Measurement Instruments checklist was used to rate the methodological quality of included studies. The level of evidence for specific measurement outcomes was determined using a best-evidence synthesis approach.

RESULTS

Reliability varied across populations, ultrasound systems, and assessment conditions (ie, joint/body positions, active/passive muscle conditions, probe orientation), with most studies indicating moderate to good reliability (ICC = 0.5-0.9, n = 13). Meta-analysis results showed a good overall correlation across studies (r = 0.78, 95% confidence interval = 0.64-0.86), with no between-group difference based on population (Q1 = 0.00). Convergent validity was demonstrated by strong correlations between stiffness values and measures of spasticity (n = 5), functional motor recovery or impairment (n = 5), and grayscale or color histogram pixel intensities (n = 3). Discriminant or known-groups validity was also established for multiple studies and indicated either significant between-group differences in stiffness values (n = 12) or within-group differences between more and less affected limbs (n = 6). Responsiveness was observed in all intervention studies reporting posttreatment stiffness changes (n = 6).

CONCLUSIONS

Overall, ultrasound elastography techniques showed moderate reliability in evaluating in vivo muscle stiffness, good convergent validity with relevant clinical assessments, and good divergent validity in discriminating tissue changes within and between groups.

IMPACT

Ultrasound elastography has clinical utility in assessing muscle stiffness, monitoring its temporal changes, and measuring the response to intervention in people with neurological conditions.

Quantitative Ultrasound Texture Analysis to Assess the Spastic Muscles in Stroke Patients

This study aimed to investigate the feasibility of sonoelastography for determining echotexture in post-stroke patients. Moreover, the relationships of muscle echotexture features, muscle stiffness, and functional performance in spastic muscle were explored. The study population comprised 22 males with stroke. The echotexture features (entropy and energy) of the biceps brachii muscles (BBM) in both arms were extracted by local binary pattern (LBP) from ultrasound images, whereas the stiffness of BBM was assessed by shear wave velocity (SWV) in the transverse and longitudinal planes. The Fugl–Meyer assessment (FMA) was used to assess the functional performance of the upper arm. The results showed that echotexture was more inhomogeneous in the paretic BBM than in the non-paretic BBM. SWV was significantly faster in paretic BBM than in non-paretic BBM. Both echotexture features were significantly correlated with SWV in the longitudinal plane. The feature of energy was significantly negatively correlated with FMA in the longitudinal plane and was significantly positively correlated with the duration from stroke onset in the transverse plane. The echotexture extracted by LBP may be a promising approach for quantitative assessment of the spastic BBM in post-stroke patients.

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.

Achilles tendon elastic properties remain decreased in long term after rupture

PURPOSE

Rupture of the Achilles tendon results in inferior scar tissue formation. Elastography allows a feasible in vivo investigation of biomechanical properties of the Achilles tendon. The purpose of this study is to investigate the biomechanical properties of healed Achilles tendons in the long term.

MATERIALS AND METHODS

Patients who suffered from Achilles tendon rupture were recruited for an elastographic evaluation. Unilateral Achilles tendon ruptures were included and scanned in the mid-substance and calcaneal insertion at least 2 years after rupture using shear wave elastography. Results were compared to patients' contralateral non-injured Achilles tendons and additionally to a healthy population. Descriptive statistics, reliability analysis, and correlation analysis with clinical scores were performed.

RESULTS

Forty-one patients were included in the study with a mean follow-up-time of 74 ± 30; [26-138] months after rupture. Significant differences were identified in shear wave elastography in the mid-substance of healed tendons (shear wave velocity 1.2 ±1.5 m/s) compared to both control groups [2.5 ±1.5 m/s (p < 0.01) and 2.8 ±1.6 m/s (p < 0.0001) contralateral and healthy population, respectively]. There was no correlation between the measurements and the clinical outcome.

CONCLUSIONS

This study shows that the healed Achilles tendon after rupture has inferior elastic properties even after a long-term healing phase. Differences in elastic properties after rupture mainly originate from the mid-substance of the Achilles tendon, in which most of the ruptures occur. Elastographic results do not correspond with subjective perception. Clinically, sonoelastographical measurements of biomechanical properties can be useful to provide objective insights in tendon recovery.

Assessment of the mechanical properties of the muscle-tendon unit by supersonic shear wave imaging elastography: a review

This review aimed to describe the state of the art in muscle-tendon unit (MTU) assessment by supersonic shear wave imaging (SSI) elastography in states of muscle contraction and stretching, during aging, and in response to injury and therapeutic interventions. A consensus exists that MTU elasticity increases during passive stretching or contraction, and decreases after static stretching, electrostimulation, massage, and dry needling. There is currently no agreement regarding changes in the MTU due to aging and injury. Currently, the application of SSI for the purpose of diagnosis, rehabilitation, and physical training remains limited by a number of issues, including the lack of normative value ranges, the lack of consensus regarding the appropriate terminology, and an inadequate understanding of the main technical limitations of this novel technology.

Shear Wave Elastography Is a Reliable and Repeatable Method for Measuring the Elastic Modulus of the Rectus Femoris Muscle and Patellar Tendon

OBJECTIVES

The purpose of this study was to determine intraobserver, interobserver, and inter-day reliability levels for stiffness measurements of the patellar tendon and rectus femoris muscle using shear wave elastography (SWE).

METHODS

This study was conducted on 12 healthy male individuals. Two examiners measured mean shear wave velocity values of the patellar tendons and rectus femoris muscles of both extremities using a 9L4 (4-9 MHz) transducer and an Acuson S3000 ultrasound system (Siemens Medical Solutions, Mountain View, CA). The elasticity images were acquired by the Virtual Touch tissue imaging quantification technique (Siemens Medical Solutions). Measurements were repeated 20 minutes and 1 week after the first measurements. The reliability of SWE measurements was assessed by means of the intraclass correlation coefficient (ICC).

RESULTS

The 12 participants ranged in age from 19 to 33 years (mean age ± SD, 25.33 ± 4.56 years). For the patellar tendon stiffness measurements with SWE, it was found that intraobserver reliability (ICC, 0.91-0.92) and interday reliability (ICC, 0.81-0.83) were excellent, and interobserver reliability (ICC, 0.71) was good. For the rectus femoris muscle stiffness measurements with SWE, it was found that the intraobserver reliability (ICC, 0.93-0.94), interday reliability (ICC, 0.81-0.91), and interobserver reliability (ICC, 0.95) were perfect.

CONCLUSIONS

Shear wave elastography using the Virtual Touch tissue imaging quantification technique is a reliable and repeatable technique for patellar tendon and rectus femoris stiffness measurements according to intraobserver, interday, and interobserver ICC values.

Reproducibility and feasibility of acoustoelastography in the superficial digital flexor tendons of clinically normal horses

OBJECTIVE

To evaluate the feasibility and repeatability of in vivo measurement of stiffness gradients by means of acoustoelastography in the superficial digital flexor tendons (SDFTs) of clinically normal horses.

ANIMALS

15 clinically normal horses.

PROCEDURES

For each horse, stiffness gradient index and dispersion values for SDFTs in both forelimbs were evaluated in longitudinal orientation by use of acoustoelastography at 3 sites (5, 10, and 15 cm distal to the accessory carpal bone) by 2 observers; for each observer, data were acquired twice per site. The left forelimb was always scanned before the right forelimb. Lifting of the contralateral forelimb with the carpus flexed during image acquisition resulted in the required SDFT deformation in the evaluated limb. Interobserver repeatability, intraobserver repeatability, and right-to-left limb symmetry for stiffness gradient index and dispersion values were evaluated.

RESULTS

Stiffness gradient index and dispersion values for SDFTs at different locations as well as effects of age or sex did not differ significantly among the 15 horses. Interclass correlation coefficients for interobserver repeatability, intraobserver repeatability, and limb symmetry revealed good to excellent agreement (intraclass correlation coefficients, > 0.74).

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that acoustoelastography is a feasible and repeatable technique for measuring stiffness gradients in SDFTs in clinically normal horses, and could potentially be used to compare healthy and diseased tendon states.

Feasibility and repeatability for in vivo measurements of stiffness gradients in the canine gastrocnemius tendon using an acoustoelastic strain gauge

B-mode ultrasound is an established imaging modality for evaluating canine tendon injury. However, full extent of tendon injury often remains difficult to estimate, as small changes in sonographic appearance are associated with large changes in biomechanical strength. The acoustoelastic strain gauge (ASG) is an ultrasound-based tissue evaluation technique that relates the change in echo intensity observed during relaxation or stretching of tendons to the tissue's mechanical properties. This technique deduces stiffness gradient (the rate of change of normalized stiffness as a function of tissue strain) by analyzing the ultrasound dynamic images captured from gradually deforming tissue. ASG has been proven to accurately model strain and stiffness within tendons in vitro. To determine the feasibility and repeatability for in vivo ASG measurements of canine tendon function, stiffness gradients for the gastrocnemius tendons of 10 clinically normal dogs were recorded by two nonindependent observers at three sites (musculotendinous junction, mid tendon, and insertion). Average stiffness gradient indices (0.0132, 0.0141, 0.0136) and dispersion values (0.0053, 0.0054, 0.0057) for each site, respectively, were consistent with published mechanical properties for normal canine tendon. Mean differences of the average stiffness gradient index and dispersion value between observers and between limbs for each site were less than 16%. Using interclass coefficients (ICC), intra-observer (ICC 0.79-0.98) and interobserver (ICC 0.77-0.95) reproducibility was good to excellent. Right and left limb values were symmetric (ICC 0.74-0.92). Findings from this study indicated that ASG is a feasible and repeatable technique for measuring stiffness gradients in canine tendons.