Supersonic Shear Wave Imaging Research Articles

Biceps brachii elastography in well-trained men post eccentric exercise-induced muscle damage.

Recent advancements in elastography techniques, specifically supersonic shearwave elastography (SWE), have enabled non-invasive assessment of muscle stiffness. However, there is limited research on the immediate and short-term effects of eccentric exercise-induced muscle damage (EIMD) in well-trained individuals. This study aimed to follow up on the effects of eccentric training on the biceps brachialis stiffness by supersonic shearwave imaging (SSI) as well as the soreness and elbow flexion maximal voluntary isometric contraction (MVIC), immediately post-intervention, at 10min, 48h, and 96h in well-trained men. Thirteen well-trained males participated in the study. Baseline measurements of elastography images, MVIC of the elbow flexors, and muscle soreness were obtained. The participants performed an eccentric exercise protocol (4 sets X 10 repetitions) on the dynamometer isokinetic and elastography measurements were repeated immediately post-exercise, at 10min, 48h, and 96h. Significant reductions in stiffness (measured by shear modulus (µ)) were observed immediately and at 10min post-exercise. MVIC exhibited significant reductions immediately after, 10min, and 48h compared to baseline measurements. Muscle soreness peaked at 48h, persisting until 96h. The BB stiffness and MVIC reduction immediately post-eccentric exercise in well-trained men, suggest the potential involvement of mechanical stress and sarcomere rupture. Trained individuals may exhibit a distinct response to EIMD compared to untrained individuals, highlighting the applicability of elastography in monitoring acute biomechanical changes following high-intensity exercise.

Acute Effects of Stretching Exercises on Posterior Chain: Analysis of Shear Modulus by Elastography SSI.

The posterior chain muscles of the lower limb include the hamstrings and triceps surae, along with the Achilles tendon. This study aimed to investigate the acute effects of static stretching exercises commonly used in clinical and training settings on the shear modulus (µ) of these muscles and tendon using Supersonic Shear-Wave Imaging (SSI) elastography. Fifteen healthy adults participated in the study, performing stretching exercises for hamstrings and triceps surae. Shear modulus and joint range of motion (ROM) were measured before and after the stretching protocols. The hip and ankle mean ROM significantly increased by 19.27% and 24.10%, respectively. However, the stretching protocol did not significantly alter in µ of the hamstrings, the gastrocnemius muscles, and the Achilles tendon. K-means clustering analysis identified a group where the subjects with lower initial ROM showed higher amplitude gains and a significant decrease in the semimembranosus stiffness after stretching. These findings suggest that the stretching protocol was effective in improving joint mobility but not sufficient to elicit immediate mechanical changes in muscle and tendon stiffness. Neural adaptations and nonmuscular structures might contribute to increased ROM. The study highlights the importance of considering individual initial ROM and subsequent responses when evaluating the effects of stretching exercises on muscle and tendon properties.

Correlation between the shear modulus measured by elastography (SSI) and tangent modulus from tensile tests of in vitro fresh-frozen human tendons

Assessing the mechanical properties of tendons in vivo allows for quantifying the degree of pathology and tracking functional improvements. The Supersonic Shearwave Imaging (SSI) technique is a state-of-the-art method for analyzing musculoskeletal tissues in vivo. This technique estimates tissue stiffness as the shear elastic modulus µ [kPa]. However, only a few studies have validated the accuracy of SSI-estimated shear modulus against the gold standard for in vitro material testing, the tensile test. This study compared the SSI-measured shear elastic modulus (µ) with the tangent modulus (Etan) obtained from mechanical tensile tests for human Achilles (AT) and patellar tendons (PT). The sample comprised eleven fresh-frozen human Achilles tendons and five fresh-frozen human patellar tendons from cadavers that were not degraded by formalin or ionizing radiation. The tendons were tested in a tensile machine, and elastography videos were collected and segmented every 5% of the total experiment time. The absolute µ values estimated from both instruments presented an up to 20-fold difference. However, a strong significant positive correlation was found between µ and Etan for both tendons (range AT: R = 0.9765–0.9972 and PT: R = 0.8719–0.9782). The two resulting curves (µ and Etan) as a function of strain (ε) were normalized by their maxima for visually comparing stiffness × strain profiles. In conclusion, despite the inaccurate absolute values, SSI has been shown to measure relative changes in human Achilles and patellar tendon stiffness. This study endorses future clinical use of SSI to provide in vivo estimations of human tendons’ mechanical properties.

Diagnostic performance of renal cortical elasticity by supersonic shear wave imaging in pediatric glomerular disease

PurposeTo explore the diagnostic performance of renal cortical elasticity expressed by Young’s modulus (YM) using the supersonic shear wave imaging (SSI) technique in pediatric glomerular disease. Materials and methodsSeventy-one children with glomerular disease confirmed by renal biopsy and sixty healthy volunteers were enrolled in this study. Conventional and SSI ultrasound examinations were performed in all individuals for both kidneys. We measured renal length, renal width, renal thickness, parenchyma thickness, interlobar arterial resistive index (RI) and the YM of the middle and lower pole. ResultsRegardless of which pole and which side of the kidney, the YM in the disease group was significantly higher than that in the control group (P < 0.001). The YM of the middle pole in the left kidney demonstrated the largest AUC (0.936, P < 0.001), and the corresponding cut-off value was 15.48 kPa with a sensitivity of 87.3% and a specificity of 86.7%. There was no significant difference in the YM among different pathological types of pediatric glomerular disease in the disease group, and the same in different grades of patients with Immunoglobulin A (IgA) nephropathy by Lee classification and the Oxford Classification as well as Henoch-Schonlein purpura nephritis (HSPN) by International Study of Kidney Disease in Children (ISKDC) classification (P > 0.05). We found positive but weak correlations between the YM and renal length (r = 0.299, P = 0.001), renal width (r = 0.408, P < 0.001), renal thickness (r = 0.299, P = 0.001), and parenchyma thickness (r = 0.212, P = 0.015), whereas the YM had no significant correlations with age, sex, BMI, interlobar arterial RI, and laboratory findings (P > 0.05). ConclusionsSSI technology is a non-invasive and feasible method for the diagnosis of pediatric glomerular disease. However, SSI did not show good performance in distinguishing different pathological types and disease grades in our study.

Supersonic shear wave imaging of the tibial nerve for diagnosis of diabetic peripheral neuropathy: A meta-analysis.

BackgroundDiabetic peripheral neuropathy (DPN) is the most common diabetes-associated complication and imposes a significant burden to healthcare systems. Thus, early diagnosis of DPN is extremely critical for management and outcome of diabetic patients. Supersonic Shear Wave Imaging (SSI) enables the noninvasive measurement of nerve stiffness. However, previous studies on SSI in the diagnosis of DPN were limited in sample sizes and reported various results. In this meta-analysis, we aimed to obtain comprehensive evidence on the value of tibial nerve stiffness measurement by SSI in the diagnosis of DPN.MethodsA comprehensive literature search in English and Chinese electronic database was conducted for studies (published until January 25, 2022) that investigated the diagnostic performance of tibial nerve stiffness measurement by SSI for detecting DPN. Summary receiver operating characteristics (SROC) modelling was constructed to conduct the meta-analysis of diagnostic accuracy of SSI for detecting DPN.ResultsFinally, a total of 12 eligible studies with 1325 subjects were included for evaluation, and a meta-analysis was conducted to evaluate the diagnostic performance of tibial nerve stiffness measurement by SSI for detecting DPN. For tibial nerve stiffness measurement by SSI, the summary sensitivity and specificity for the diagnosis of DPN were 80% (95% confidence interval [CI]: 73%–86%) and 86% (95% CI: 82%–89%), respectively. The summary area under the ROC curve (AUROC) value of the SROC was 0.90 (95% CI: 0.87–0.92), for diagnosing DPN. A subgroup analysis of 11 SSI studies from China revealed similar diagnostic performance, with a summary sensitivity of 79% (95% CI: 72%–85%), specificity of 86% (95% CI: 82%–89%) and summary AUROC value of the SROC of 0.90 (95% CI: 0.87–0.92) for diagnosing DPN.ConclusionsOur meta-analysis suggests that a tibial nerve stiffness measurement by SSI shows good performance in diagnosing DPN and has considerable potential as a noninvasive tool for detecting DPN.

Comparison of Supersonic Shear Wave Imaging–Derived Renal Parenchyma Stiffness Between Diabetes Mellitus Patients With and Without Diabetic Kidney Disease

This study aims to evaluate the difference in renal parenchyma stiffness assessed by measuring Young's modulus (YM) using a supersonic shear wave imaging (SSI) technique among healthy patients and patients with type 2 diabetes mellitus (DM) with and without diabetic kidney disease (DKD). We analyzed the correlations of YM with clinical information and conventional ultrasound parameters. All patients (N = 124) were divided into three groups: (i) healthy patients (patients without kidney disease or type 2 DM, N = 31); (ii) patients with type 2 DM without kidney disease (N = 38); and (iii) patients with DKD (N = 55). Conventional and SSI ultrasound examinations were performed in all individuals for both kidneys. Then, we recorded renal length, width, parenchyma thickness, interlobar arterial resistive index (RI) and values of mean, mininum and maximum YM. The mean values of these parameters for the left and right kidneys were calculated for statistical analysis. Statistical significance was considered at p < 0.05. Among all ultrasound parameters, the mean YM demonstrated the largest area under the receiver operating characteristic (ROC) curve (0.860). The areas under the ROC curve (AUCs) for renal length, width, parenchyma thickness, interlobar arterial RI, minimum YM and maximum YM were 0.493, 0.616, 0.507, 0.733, 0.848 and 0.794, respectively. The corresponding cutoff value of mean YM was 31.73 kPa, with a sensitivity of 85.5% and a specificity of 71.0%. The mean YM in patients with type 2 DM without kidney disease (31.44 ± 3.83 kPa) was significantly higher than that in the healthy group (26.45 ± 4.32 kPa) and lower than that in the DKD group (37.60 ± 6.56 kPa). Patients with type 2 DM without kidney disease were considered as stage 0 of DKD. Thus, the mean YM in the control group was significantly lower than that in the stage 0, 2, 3, 4 and 5 subgroups. The mean YM in the stage 0–2 subgroups was lower than that in the stage 5 group, and the mean YM in the stage 0 group was lower than that in the stage 4 group. In the DKD group, the mean YM had a positive correlation with cystine-c (r = 0.634), urea (r = 0.596), creatine (r = 0.690), uric acid (r = 0.263), albumin/creatinine ratio (r = 0.428) and the presence or absence of diabetic retinopathy (r = 0.354). The mean YM also had a negative correlation with the estimated glomerular filtration rate (r = –0.657). SSI is a non-invasive method with which to diagnose DKD and has a performance superior to that of conventional ultrasound. In addition, SSI may provide a secondary index for the staging of DKD and the monitoring of renal damage in type 2 DM patients.

A Preliminary Study on Quantitative Quality Measurements of the Urethral Rhabdosphincter Muscle by Supersonic Shear Wave Imaging in Women With Stress Urinary Incontinence.

To quantitatively assess the quality of the urethral rhabdosphincter muscle by measuring its shear wave velocity (Vs ) and calculating the Young modulus (E) with supersonic shear wave imaging (SSI). This was a prospective study of 43 women with SUI and 52 female control participants who underwent a transperineal US examination with SSI. Supersonic shear wave imaging was performed at rest with a linear transducer and a specialized-preset procedure. The stability and validity of the shear waves were automatically assessed by the SSI procedure. The SSI images were visualized in a color-coded elastographic image. In the postprocessing analysis, the ventral part of the urethral rhabdosphincter muscle was manually outlined. The mean Vs and the mean E of the muscle were measured by the SSI procedure. The relationship between the mean Vs , mean E, and SUI was evaluated. The SSI examination was successfully performed in 40 patients with SUI (93.0%) and 40 female control participants (76.9%). No significant differences between the groups in age, body mass index, and parity were identified. For the SUI and control groups, the mean Vs values were 2.54 and 2.73 m/s, respectively, and the mean E values were was 19.7 and 22.7kPa. Significant correlations were found between SUI and the mean Vs as well as the mean E (Spearman correlation coefficients, -0.41 and -0.43; P < .05). The mechanical properties of the urethral sphincter can be quantitatively assessed by SSI. The stiffness of the urethral rhabdosphincter muscle was significantly lower in women with SUI.

Liver stiffness and perfusion changes for hepatic sinusoidal obstruction syndrome in rabbit model.

BACKGROUNDHepatic sinusoidal obstruction syndrome (SOS) is caused by damage to hepatic sinusoidal endothelial cells that results in fibrous obliteration of intrahepatic venules and necrosis of hepatocytes. Currently the diagnosis is primarily based on nonspecific clinical features and invasive liver biopsy. Therefore, noninvasive imaging methods are required for the early diagnosis and severity assessment of hepatic SOS.AIMTo determine the effectiveness of supersonic shear wave imaging (SSI) and dual energy computed tomography (DECT) for diagnosing hepatic SOS using a rabbit model.METHODSAmong nine New Zealand white rabbits (3-4 kg, male), three in control group ingested normal saline for 20 d and six in the SOS group ingested 6-thioguanine (5 mg/kg/d) for 20 d. Liver stiffness was measured using SSI on days 0, 3, 10, and 20. On the same days, liver perfusion was evaluated from virtual monochromatic images of 55 keV and iodine map using DECT. Morphologic changes in the liver were assessed using CT. Final pathology scores were compared between the two groups. Liver stiffness and perfusion parameters were compared according to the groups, days, and pathology scores.RESULTSFinal pathology scores were significantly higher in the SOS than the control group (median 22 vs 2, P = 0.024). No gross morphologic changes were seen in livers. Liver stiffness, Hounsfield Unit values, and iodine concentrations were higher in the SOS compared to the control group on days 10 and 20 (all, P ≤ 0.007). Compared to day 0, liver stiffness and perfusion parameters were higher on day 20 in the SOS group (all, P ≤ 0.001). Correlation coefficients for liver stiffness (r = 0.635), Hounsfield Unit values (r = 0.587), and iodine concentration (r = 0.611) with final pathology scores were positive without significance (all, P > 0.05).CONCLUSIONLiver stiffness and perfusion parameters were significantly increased in the livers of a rabbit SOS model. SSI and DECT might aid in early diagnosis of hepatic SOS.

ELASTOGRAPHIC ANALYSIS OF THE SUPRASPINATUS TENDON IN DIFFERENT AGE GROUPS.

ABSTRACTObjective: To compare the mechanical properties of the supraspinatus tendon in different age groups using Supersonic Shearwave Imaging (SSI) elastography.Methods: We evaluated 38 healthy individuals of both genders, 20 being in the range of 20 to 35 years and 18 being over 60 years. The shear modulus of the supraspinatus tendon was measured by SSI elastography, always on the right side. Means between age groups were compared and statistically analyzed using the Shapiro-Wilk normality test followed by the student’s t-test and were established as a statistically significant value of p ≤ 0.05.Results: A statistically significant difference was observed when the mean values of the shear modulus of the supraspinatus tendon of young adults (23.98 ± 9.94 KpA) were compared with those of older adults (17.92 ± 6.17 KpA).Conclusion: We found a difference between the means of the shear modulus measured by the SSI elastography, showing a significant decrease of the shear modulus with the chronological age progression. Level of Evidence III, Diagnostic Studies - Investigating a Diagnostic Test.

Quantification of Upper Trapezius Muscle Stiffness Using Supersonic Shear Wave Imaging: Efficacy of Workplace-based Exercise Programme to Reduce Neck and Shoulder Disorders in Working Population

Quantification of Upper Trapezius Muscle Stiffness Using Supersonic Shear Wave Imaging: Efficacy of Workplace-based Exercise Programme to Reduce Neck and Shoulder Disorders in Working Population

Pulmonary Capillary Hemorrhage Induced by Super Sonic Shear Wave Elastography in Rats

The occurrence of the pulmonary capillary hemorrhage (PCH) bioeffect of diagnostic ultrasound in rats was investigated for a SuperSonic Imagine shear wave elastography system (Aixplorer, Supersonic Imagine, Aix-en-Provence, France). The elastography imaging repeated at 1 Hz and consisted of widely spaced B-mode image pulses, supersonic push (SSP) pulses and shear wave imaging (SWI) pulses. Groups of rats anesthetized with ketamine and xylazine, or with ketamine only, were imaged on their right side in a warm water bath for one frame, 30 s and 300 s. The image focus and region of interest were adjusted to give exposure only with the background B-mode imaging, or primarily with the SSP and SWI pulses. A sham group had only low power aiming scans. The lungs were removed 5 min after exposure and evaluated for PCH area and volume. The B mode was notably ineffective and produced significant PCH only at the maximum 0 dB output. The SSP pulses together with the SWI pulses produced significant PCH for 300 s, 30 s and even single image exposures. Peak rarefactional pressure amplitude PCH thresholds for 300 s exposure were the same with or without the B-mode pulses at 1.5 MPa (in situ mechanical index, MIIS = 0.67). A 30 s duration resulted in a slightly increased threshold of 1.7 MPa (MIIS = 0.76). The omission of xylazine from the anesthetic, which reduces the sensitivity of rat lung to PCH occurrence, resulted in an increased threshold of 2.1 MPa (MIIS = 0.94). The unique SSP pulses were much more effective than the B mode, but thresholds were comparable to previous results with other diagnostic ultrasound modes on other systems.

Semitendinosus and patellar tendons shear modulus evaluation by supersonic shearwave imaging elastography.

Shear modulus (μ) is directly correlated to the tissue stiffness and can predict the tendon ultimate force to failure. With the knee extended 0° (K0), semitendinosus tendon (ST) is tensioned while patellar tendon (PT) is relaxed. At 80o , knee flexion (K80) tendons present an opposite stress pattern; however, the relation between ST and PT μ in both situations was not studied yet. We accessed the μ of the ST and PT at 0o and 80o knee flexion by supersonic shear wave imaging (SSI) elastography from 18 healthy males. Relative μ indexes were calculated for relaxed and tensioned conditions. The average μ for ST was μST-K0 =197·62±31·93 kPa and μST-K80 =77·76±30·08. For TP, values were μTP-K0 =23·45±5·89 and μTP-K80 =113·92±57·23 kPa. Relative μ indexes were calculated for relaxed (IR=μST-K80 /μTP-K0 ) and tensioned conditions (IT=μST-K0 /μPT-K80 ). The relative μ indexes were IR=3·63±1·50 and IT=2·00±0·96 (P<0·05). Semitendinosus tendon μ was significantly higher than PT μ in both tensioned and relaxed positions. This can predict a higher ultimate force to failure and a less elastic behaviour in ST grafts when compared to PT grafts. This new parameter could aid physicians in graft choice previous to anterior cruciate ligament reconstruction.

Motion effects on the measurement of stiffness on ultrasound shear wave elastography: a moving liver fibrosis phantom study.

To evaluate the differences between shear wave velocities (SWVs) measured with ultrasound elastography duringthe continuous motion using liver fibrosis phantoms. Elasticities were measured with convex andlinear transducers of supersonic shear wave imaging (SSI) and acoustic radiation force impulse imaging (ARFI) using liverelasticity phantoms (3.0 and 16.9 kPa) at depths of 2, 3, 4, and 5 cm. Motion velocities were 30 and 60 rpm with the phantomsin an upright position on the Orbital shaker. To simulate different directional motion, the phantoms were laid on their side on the shaker. The values between moving and static status were compared, and the number of measurement failure was counted.Results: In SSI, the convex transducer was less affected by motion at 30 rpm with the 3 kPa phantom. In the higher velocitymotion and in the higher stiffness phantom, most values from SSI were different comparing with static status, and there was atendency for elasticity values to increase during movement. In ARFI, there were frequent measurement failures without stableresults during the motion. Motion affected the measurement of elasticity differently in SSI and ARFI, accordingto the velocity, direction of the motion, and phantom stiffness. The convex transducer of SSI was less affected by motion inlower velocity motion and when using normal liver stiffness phantom.

Analysis of the correlation between knee extension torque and patellar tendon elastic property.

Quadriceps strength and patellar tendon (PT) are directly linked and intimately related to daily activities and lower limb function. However, the correlation between knee extension torque (KT) and PT Young's modulus (E) measured directly is still unknown. We used supersonic shearwave imaging (SSI) to evaluate the elastic property of PT in healthy young men and analysed its correlation with KT. Twenty-two healthy young males were included and both knees were examined. The E of the PT in the dominant and non-dominant legs was assessed by SSI elastography. KT in maximal voluntary isometric contraction was measured with an isokinetic dynamometer. No correlations between KT and PT E were observed in dominant or non-dominant side (P=0·458 and 0·126, respectively). No significant differences in KT or PT E were observed between both legs (P=0·096 and 0·722, respectively). Intra-day ICC was rated good (D1 - 0·886, P<0·001 and 0·88, P<0·001) and excellent (D2 - 0·928, P<0·001 and 0·900, P<0·001) for both legs. Inter-day ICC was rated moderate for both legs (0·651, P=0·016 and 0·630, P=0·018, respectively). No significant correlations were found between KT and PT E, suggesting that quadriceps strength is not an accurate predictor for PT mechanical properties in subjects with no specific training engagement. Habitual loading pattern can play a determinant role in PT mechanical properties, regardless of quadriceps strength. Further investigation on SSI acquisition protocols should be conducted to guarantee higher inter-day ICC values.

Supersonic Shear Wave Imaging of the Spleen for Staging of Liver Fibrosis in Rats

The goal of the work described here was to explore the cause of spleen stiffness (SS) in hepatic fibrogenesis and evaluate the value of SS in liver fibrosis (LF) staging. LF was induced with carbon tetrachloride (CCl4) in rats (n = 40). Supersonic shear wave imaging and contrast-enhanced ultrasound were performed to determine liver stiffness (LS), SS and splenic hemodynamics. SS, LS and free portal pressure exhibited moderate correlations with fibrosis stage (r = 0.744–0.835, p < 0.001). Time–intensity curves of contrast-enhanced ultrasound for the spleen were presented as decreasing peak intensity and slope of decrease, and increasing time to peak. Splenic sinus dilation and congestion were observed on histopathologic analysis. The area under the receiver operating characteristic curve of SS was higher than that of LS for differentiating LF stages 0–2 from stages 3–4 (Z = 2.293, p = 0.02). SS is a reliable diagnostic marker for the assessment of LF in the CCl4 model, especially for severe fibrosis. Elevated portal pressure is the cause of increasing SS.

Nonlinear elasticity imaging with dual frequency ultrasound

Elasticity imaging has shown to enhance diagnostic capabilities of disease as tissue elasticity is often associated with pathological condition. Methods such as Acoustic Radiation Force Impulse imaging and Supersonic Shear Wave imaging have shown good results at shallow depths. Second-order ultrasound field (SURF) imaging is a dual band imaging technique that utilizes a low frequency (LF) pulse to manipulate the nonlinear elasticity of the medium observed by a co-propagating high frequency pulse (HF). The manipulation of the material parameters causes the HF to experience a change in propagation velocity which depends on the manipulation pressure and nonlinear elasticity of the medium. The change in propagation velocity causes an accumulative delay or advancement compared to a single HF pulse, called the nonlinear propagation delay (NPD). By transmitting multiple pulse complexes with different LF polarities the technique has proven capabilities for suppression of multiple scattering noise. By observing local variations in the development of NPD, it is possible to estimate the nonlinear elasticity variation of the medium. Simulations with k-Wave toolbox have shown the methods feasibility, also at greater depths. In-vitro and in-vivo experiments have also yielded promising results.

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 Measurements for Evaluation of Tendon Diseases.

This paper investigated the feasibility of using supersonic shear wave measurements to quantitatively differentiate normal and damaged tendons based on their mechanical properties. Five freshly harvested porcine tendons excised from pig legs were used. Tendon damage was induced by incubating the tendons with a 1% w/v collagenase solution. Values of shear modulus were derived both by a time-of-flight (TOF) approach and a transverse isotropic plate model (TI-model). The results show that as the preload applied to the tendon increased from 0 to 3 N, the mean shear modulus derived based on the TOF approach, the TI-model, and Young's modulus estimated from mechanical testing increased from 14.6 to 89.9 kPa, 53.9 to 348 kPa, and from 1.45 to 10.36 MPa, respectively, in untreated tendons, and from 8.4 to 67 kPa, 28 to 258 kPa, and from 0.93 to 7.2 MPa in collagenase-treated tendons. Both the TOF approach and the TI-model correlated well with the changes in Young's modulus. Although there is bias on the estimation of shear modulus using the TOF approach, it still provides statistical significance to differentiate normal and damaged tendons. Our data indicate that supersonic shear wave imaging is a valuable imaging technique to assess tendon stiffness dynamics and characterize normal and collagenase-damaged tendons.

Increase in passive muscle tension of the quadriceps muscle heads in jumping athletes with patellar tendinopathy.

To investigate the passive muscle tension of the quadriceps muscle heads in male athletes clinically diagnosed with patellar tendinopathy (PT) with those of healthy controls and explore the interplay between passive muscle tension and patellar tendon stiffness. Between November 2012 and December 2013, 66 male athletes (mean age of 21.1±4.4years) were examined using supersonic shear wave imaging technology. The passive tension of the vastus lateralis (VL) and rectus femoris (RF) muscles and patellar tendon stiffness were assessed. The shear elastic modulus of the VL muscle was increased by 26.5% (P<0.001) in the subjects with PT when compared with the controls. Greater passive tension in the VL was associated with higher patellar tendon stiffness (r=0.38; P=0.001). The vastus lateralis muscle of the quadriceps shows increase in passive muscle tension in jumping athletes with patellar tendinopathy. These findings suggest that increase in muscle tension is not similar in the individual muscles of the quadriceps muscle. Traditional stretching of the whole quadriceps muscle might not be targeted to the tight muscle heads.

Shear wave elastography using ultrasound: effects of anisotropy and stretch stress on a tissue phantom and in vivo reactive lymph nodes in the neck

PurposeThe purpose of this study was to evaluate how the anisotropy and the static stretch stress of the cervical musculature influence the measured shear modulus in a tissue-mimicking phantom and in cervical lymph nodes in vivo by using shear wave elastography (SWE).MethodsSWE was performed on a phantom using a pig muscle and on the middle jugular cervical lymph nodes in six volunteers. Tissue elasticity was quantified using the shear modulus and a supersonic shear wave imaging technique. For the phantom study, first, the optimal depth for measurement was determined, and then, SWE was performed in parallel and perpendicular to the muscle fiber orientation with and without strain stress. For the in vivo study, SWE was performed on the cervical lymph nodes in parallel and perpendicular to the sternocleidomastoid muscle fiber direction with and without neck stretching. The mean values of the shear modulus (meanSM) were then analyzed.ResultsIn the phantom study, the measured depth significantly influenced the meanSM with a sharp decrease at the depth of 1.5 cm (P<0.001). Strain stress increased the meanSM, irrespective of the muscle fiber orientation (P<0.001). In the in vivo study, the meanSM values obtained in parallel to the muscle fiber orientation were greater than those obtained perpendicular to the fiber orientation, irrespective of the stretch stress (P<0.001). However, meanSM was affected significantly by the stretch stress parallel to the muscle fiber orientation (P<0.001).ConclusionThe anisotropic nature of the cervical musculature and the applied stretch stress explain the variability of the SWE measurements and should be identified before applying SWE for the interpretation of the measured shear modulus values.