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Billy J, Bensamoun SF, Mercier J, Durand S. Applications of ultrasound elastography to hand and upper limb disorders. HAND SURGERY & REHABILITATION 2024; 43:101636. [PMID: 38215880 DOI: 10.1016/j.hansur.2024.101636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/22/2023] [Accepted: 12/24/2023] [Indexed: 01/14/2024]
Abstract
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.
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Affiliation(s)
- Jessica Billy
- Department of Hand Surgery, Lausanne University Hospital, University of Lausanne, 1011 Lausanne, Switzerland
| | - Sabine F Bensamoun
- Sorbonne University, Université de Technologie de Compiègne, CNRS UMR 7338, Biomechanics and Bioengineering, Compiègne, France
| | - Julie Mercier
- Department of Hand Surgery, Lausanne University Hospital, University of Lausanne, 1011 Lausanne, Switzerland
| | - Sébastien Durand
- Department of Hand Surgery, Lausanne University Hospital, University of Lausanne, 1011 Lausanne, Switzerland.
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Wen S, Peng B, Wei X, Luo J, Jiang J. Convolutional Neural Network-Based Speckle Tracking for Ultrasound Strain Elastography: An Unsupervised Learning Approach. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2023; 70:354-367. [PMID: 37022912 DOI: 10.1109/tuffc.2023.3243539] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Accurate and computationally efficient motion estimation is a critical component of real-time ultrasound strain elastography (USE). With the advent of deep-learning neural network models, a growing body of work has explored supervised convolutional neural network (CNN)-based optical flow in the framework of USE. However, the above-said supervised learning was often done using simulated ultrasound data. The research community has questioned whether simulated ultrasound data containing simple motion can train deep-learning CNN models that can reliably track complex in vivo speckle motion. In parallel with other research groups' efforts, this study developed an unsupervised motion estimation neural network (UMEN-Net) for USE by adapting a well-established CNN model named PWC-Net. Our network's input is a pair of predeformation and postdeformation radio frequency (RF) echo signals. The proposed network outputs both axial and lateral displacement fields. The loss function consists of a correlation between the predeformation signal and the motion-compensated postcompression signal, smoothness of the displacement fields, and tissue incompressibility. Notably, an innovative correlation method known as the globally optimized correspondence (GOCor) volumes module developed by Truong et al. was used to replace the original Corr module to enhance our evaluation of signal correlation. The proposed CNN model was tested using simulated, phantom, and in vivo ultrasound data containing biologically confirmed breast lesions. Its performance was compared against other state-of-the-art methods, including two deep-learning-based tracking methods (MPWC-Net++ and ReUSENet) and two conventional tracking methods (GLUE and BRGMT-LPF). In summary, compared with the four known methods mentioned above, our unsupervised CNN model not only obtained higher signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) for axial strain estimates but also improved the quality of the lateral strain estimates.
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Quilling GM, Lee KS, Ebben B. Shear wave elastography imaging in a porcine tendinopathy model. Skeletal Radiol 2022; 51:2167-2173. [PMID: 35639127 DOI: 10.1007/s00256-022-04073-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 05/10/2022] [Accepted: 05/11/2022] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To quantify the effect of structural damage in an ex vivo animal tendinopathy model using shear wave elastography (SWE). MATERIALS AND METHODS Sixteen porcine flexor tendons were injected with a 0.05 mL bolus of 1.5% collagenase solution to induce focal structural damage without surfacing tears. Control tendons were injected with saline (n = 16). Eight tendons from each group were incubated at 37 °C for 3.5 h while the remaining 8 from each group were incubated for 7 h. Tendons were mechanically stretched to 0% and 1% strain. Simultaneously, SWE was acquired proximal to, at, and distal to the injection site using a clinical ultrasound scanner. RESULTS There were significant differences in SWS (saline > collagenase) at 1% strain and 7-h incubation for all three locations (PROX p = 0.0031, ROI p = 0.001, DIST p = 0.0043). There were also significant differences at 0% strain and 7 h, but only at (p = 0.0005), and distal to (p = 0.0035), the injection site. No statistically significant differences were observed for 3.5-h incubation, at 0% or 1% strain. CONCLUSIONS Collagenase-mediated structural damage does appear to convey decreased tissue elasticity on SWE when ex vivo tendons are incubated for 7 h. These findings suggest that SWE may be a useful tool for predicting ultimate tissue strength in tendinopathic tissues. Pull-to-failure testing should be performed in the future and are expected to show that tendons with decreased SWS, and, therefore, decreased elasticity, rupture at lower pulls forces.
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Affiliation(s)
- Grant M Quilling
- School of Medicine and Public Health, University of Wisconsin, 750 Highland Ave, Madison, WI, 53726, USA
| | - Kenneth S Lee
- Department of Radiology, University of Wisconsin Hospitals and Clinics, 621 Science Drive, Madison, WI, 53711, USA.
| | - Beau Ebben
- Department of Radiology, University of Wisconsin Hospitals and Clinics, 621 Science Drive, Madison, WI, 53711, USA
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Blank J, Blomquist M, Arant L, Cone S, Roth J. Characterizing Musculoskeletal Tissue Mechanics Based on Shear Wave Propagation: A Systematic Review of Current Methods and Reported Measurements. Ann Biomed Eng 2022; 50:751-768. [PMID: 35359250 PMCID: PMC9631468 DOI: 10.1007/s10439-022-02935-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 02/11/2022] [Indexed: 12/17/2022]
Abstract
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.
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Affiliation(s)
- Jonathon Blank
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Matthew Blomquist
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Lesley Arant
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Stephanie Cone
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Joshua Roth
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA.
- Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 1111 Highland Ave WIMR 5037, Madison, WI, 53705, USA.
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6
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Abstract
Over the past decade, ultrasound elastography has emerged as a new technique for measuring soft tissue properties. Real-time, noninvasive, and quantitative evaluations of tissue stiffness have improved and aid in the assessment of normal and pathological conditions. Specifically, its use has substantially increased in the evaluation of muscle, tendon, and ligament properties. In this review, the authors describe the principles of elastography and present different techniques including strain elastography and shear-wave elastography; discuss their applications for assessing soft tissues in the hand before, during, and postsurgeries; present the strengths and limitations of their measurement capabilities; and describe directions for future research.
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Affiliation(s)
- Hugo Giambini
- Department of Biomedical Engineering and Chemical Engineering, University of Texas at San Antonio, College of Engineering and Integrated Design, One UTSA Circle, San Antonio, TX 78249, USA.
| | - Kai-Nan An
- Mayo Clinic College of Medicine, 200 First Street, S.W, Rochester, MN 55905, USA
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7
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Rosen D, Jiang J. Analyzing acoustoelastic effect of shear wave elastography data for perfused and hydrated soft tissues using a macromolecular network inspired model. J Biomech 2019; 97:109370. [PMID: 31606128 PMCID: PMC8011867 DOI: 10.1016/j.jbiomech.2019.109370] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 09/19/2019] [Accepted: 09/22/2019] [Indexed: 12/18/2022]
Abstract
Shear wave elastography (SWE) has enhanced our ability to non-invasively make in vivo measurements of tissue elastic properties of animal and human tissues. Recently, researchers have taken advantages of acoustoelasticity in SWE to extract nonlinear elastic properties from soft biological tissues. However, most investigations of the acoustoelastic effects of SWE data (AE-SWE) rely on classic hyperelastic models for rubber-like (dry) materials. In this paper, we focus solely on understanding acoustoelasticity in soft hydrated tissues using SWE data and propose a straightforward approach to modeling the constitutive behavior of soft tissue that has a direct microstructural/macromolecular interpretation. Our approach incorporates two constitutive features relevant to biological tissues into AE-SWE: static dilation of the medium associated with nonstructural components (e.g. tissue hydration and perfusion) and finite extensibility derived from an ideal network of biological filaments. We evaluated the proposed method using data from an in-house tissue-mimicking phantom experiment, and ex vivo and in vivo AE-SWE data available in the SWE literature. In conclusion, predictions made by our approach agreed well with measurements obtained from phantom, ex vivo and in vivo tissue experiments.
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Affiliation(s)
- D Rosen
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, USA
| | - J Jiang
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, USA.
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Rosen DP, Jiang J. A comparison of hyperelastic constitutive models applicable to shear wave elastography (SWE) data in tissue-mimicking materials. Phys Med Biol 2019; 64:055014. [PMID: 30673637 DOI: 10.1088/1361-6560/ab0137] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Shear wave elastography (SWE) techniques have received substantial attention in recent years. Strong experimental data in SWE suggest that shear wave speed changes significantly due to the known acoustoelastic effect (AE). This presents both challenges and opportunities toward in vivo characterization of biological soft tissues. In this work, under the framework of continuum mechanics, we model a tissue-mimicking material as a homogeneous, isotropic, incompressible, hyperelastic material. Our primary objective is to quantitatively and qualitatively compare experimentally measured acoustoelastic data with model-predicted outcomes using multiple strain energy functions. Our analysis indicated that the classic Neo-Hookean and Mooney-Rivlin models are inadequate for modeling the AE in tissue-mimicking materials. However, a subclass of strain energy functions containing both high-order/exponential term(s) and second-order invariant dependence showed good agreement with experimental data. Based on data investigated, we also found that discrepancies may exist between parameters inversely estimated from uniaxial compression and SWE data. Overall, our findings may improve our understanding of clinical SWE results.
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Affiliation(s)
- D P Rosen
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI, United States of America
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Wang Y, Jiang J. A two-dimensional (2D) systems biology-based discrete liver tissue model: A simulation study with implications for ultrasound elastography of liver fibrosis. Comput Biol Med 2018; 104:227-234. [PMID: 30529712 DOI: 10.1016/j.compbiomed.2018.11.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/30/2018] [Accepted: 11/30/2018] [Indexed: 12/18/2022]
Abstract
Continuum tissue models that were often used to simulate or analyze the mechanical properties of tissues being imaged may not be biologically realistic. Our primary objective was to establish the feasibility of using systems biology to construct biologically relevant tissue models linking tissue structure, composition and architecture to the ultrasound measurements directly. The first application was designated to model fibrotic liver tissues. The proposed liver tissue model leveraged established histopathology knowledge of fibrotic liver tissues. Particularly, rules of systems biology derived from molecular histopathology were first implemented into an agent-based software platform SPARK to reflect progressions of liver fibrosis with/without steatosis. Then, microscopic compositions of tissues (e.g. cellular components) were converted to computing grids (at the 50-100 μm scale) for wave simulations using an open-source K-Wave. To verify the physical soundness of the proposed model, virtual wave speed measurements (i.e. shear wave speed [SWS] and the speed of sound [SOS]) were performed. Our initial results demonstrated that the simulated SWS values increased with the progression of liver fibrosis (from 1.5 m/s [Fibrosis stage 1] to 4 m/s [Fibrosis stage 4]). Similarly, the simulated SOS values were within the range of clinical data (from 1575 m/s [Fibrosis stage 0-3] to 1594 m/s [Fibrosis stage 4]). In summary, we found that those systems biology simulated fibrotic liver tissues with and without steatosis can reflect spatial characteristics of relevant histology. Also, their mechanical characteristics (i.e. shear/compressional wave speed) were in good agreement with data reported in the clinical literature.
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Affiliation(s)
- Yu Wang
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI, 49931, USA
| | - Jingfeng Jiang
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI, 49931, USA; Department of Mechanical Engineering and Engineering Mechanics, Michigan Technological University, Houghton, MI, 49931, USA.
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Martin JA, Brandon SCE, Keuler EM, Hermus JR, Ehlers AC, Segalman DJ, Allen MS, Thelen DG. Gauging force by tapping tendons. Nat Commun 2018; 9:1592. [PMID: 29686281 PMCID: PMC5913259 DOI: 10.1038/s41467-018-03797-6] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 03/13/2018] [Indexed: 12/18/2022] Open
Abstract
Muscles are the actuators that drive human movement. However, despite many decades of work, we still cannot readily assess the forces that muscles transmit during human movement. Direct measurements of muscle-tendon loads are invasive and modeling approaches require many assumptions. Here, we introduce a non-invasive approach to assess tendon loads by tracking vibrational behavior. We first show that the speed of shear wave propagation in tendon increases with the square root of axial stress. We then introduce a remarkably simple shear wave tensiometer that uses micron-scale taps and skin-mounted accelerometers to track tendon wave speeds in vivo. Tendon wave speeds are shown to modulate in phase with active joint torques during isometric exertions, walking, and running. The capacity to non-invasively assess muscle-tendon loading can provide new insights into the motor control and biomechanics underlying movement, and could lead to enhanced clinical treatment of musculoskeletal injuries and diseases.
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Affiliation(s)
- Jack A Martin
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Scott C E Brandon
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA.,School of Engineering, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Emily M Keuler
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - James R Hermus
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Alexander C Ehlers
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Daniel J Segalman
- Engineering Physics Department, University of Wisconsin-Madison, Madison, WI, 53706, USA.,Department of Mechanical Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - Matthew S Allen
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA.,Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA.,Engineering Physics Department, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Darryl G Thelen
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA. .,Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA. .,Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA. .,Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI, 53706, USA.
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11
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Ultrasound elastography of the lower uterine segment in women with a previous cesarean section: Comparison of in-/ex-vivo elastography versus tensile-stress-strain-rupture analysis. Eur J Obstet Gynecol Reprod Biol 2018; 225:172-180. [PMID: 29729520 DOI: 10.1016/j.ejogrb.2018.04.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/10/2018] [Indexed: 01/05/2023]
Abstract
OBJECTIVES The purpose of this study was to assess, if the biomechanical properties of the lower uterine segment (LUS) in women with a previous cesarean section (CS) can be determined by ultrasound (US) elastography. The first aim was to establish an ex-vivo LUS tensile-stress-strain-rupture(break point) analysis with the possibility of simultaneously using US elastography. The second aim was to investigate the relationship between measurement results of LUS stiffness using US elastography in-/ex-vivo with results of tensile-stress-strain-rupture analysis, and to compare different US elastography LUS-stiffness-measurement methods ex-vivo. STUDY DESIGN An explorative experimental, in-/ex-vivo US study of women with previous CS was conducted. LUS elasticity was measured by point Shear Wave Elastography (pSWE) and bidimensional Shear-Wave-Elastography (2D-SWE) first in-vivo during preoperative examination within 24 h before repeat CS (including resection of the thinnest part of the LUS = uterine scar area during CS), second within 1 h after operation during the ex-vivo experiment, followed by tensile-stress-strain-rupture analysis. Pearson's correlation coefficient and scatter plots, Bland-Altman plots and paired T-tests, were used. RESULTS Thirty three women were included in the study; elastography measurements n = 1412. The feasibility of ex-vivo assessment of LUS by quantitative US elastography using pSWE and 2D-SWE to detect stiffness of LUS was demonstrated. The strongest correlation with tensile-stress-strain analysis was found in the US elastography examination carried out with 2D-SWE (0.78, p < 0.001, 95%CI [0.48, 0.92]). The laboratory experiment illustrated that, the break point - as a surrogate marker for the risk of rupture of the LUS after CS - is linearly dependent on the thickness of the LUS in the scar area (Coefficient of correlation: 0.79, p < 0.001, 95%CI [0.55, 0.91]). Two extremely stiff LUS-specimens (outlier or extreme values) rupture even at less stroke/strain than would be expected by their thickness. CONCLUSION This study confirms that US elastography can help in determining viscoelastic properties of the LUS in women with a previous CS. The data from our small series are promising. However whether individual extreme values of high stiffness and consecutive restricted biomechanical resilience can explain the phenomenon of rupture during TOLAC in cases of LUS with adequate thickness remains a question which prospective trials have to analyze before US elastography can be introduced into clinical practice.
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Coombes BK, Tucker K, Vicenzino B, Vuvan V, Mellor R, Heales L, Nordez A, Hug F. Achilles and patellar tendinopathy display opposite changes in elastic properties: A shear wave elastography study. Scand J Med Sci Sports 2017; 28:1201-1208. [PMID: 28972291 DOI: 10.1111/sms.12986] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2017] [Indexed: 12/17/2022]
Abstract
To compare tendon elastic and structural properties of healthy individuals with those with Achilles or patellar tendinopathy. Sixty-seven participants (22 Achilles tendinopathy, 17 patellar tendinopathy, and 28 healthy controls) were recruited between March 2015 and March 2016. Shear wave velocity (SWV), an index of tissue elastic modulus, and tendon thickness were measured bilaterally at mid-tendon and insertional regions of Achilles and patellar tendons by an examiner blinded to group. Analysis of covariance, adjusted for age, body mass index, and sex was used to compare differences in tendon thickness and SWV between the two tendinopathy groups (relative to controls) and regions. Tendon thickness was included as a covariate for analysis of SWV. Compared to controls, participants with Achilles tendinopathy had lower SWV at the distal insertion (Mean difference MD; 95% CI: -1.56; -2.49 to -0.62 m/s; P < .001) and greater thickness at the mid-tendon (MD 0.19; 0.05-0.33 cm; P = .007). Compared to controls, participants with patellar tendinopathy had higher SWV at both regions (MD 1.25; 0.40-2.10 m/s; P = .005) and greater thickness proximally (MD 0.17; 0.06-0.29 cm; P = .003). Compared to controls, participants with Achilles and patellar tendinopathy displayed lower Achilles tendon elastic modulus and higher patellar tendon elastic modulus, respectively. More research is needed to explore whether maturation, aging, or chronic load underlie these findings and whether current management programs for Achilles and patellar tendinopathy need to be tailored to the tendon.
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Affiliation(s)
- B K Coombes
- School of Biomedical Sciences, The University of Queensland, Brisbane, Qld, Australia
| | - K Tucker
- School of Biomedical Sciences, The University of Queensland, Brisbane, Qld, Australia
| | - B Vicenzino
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Qld, Australia
| | - V Vuvan
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Qld, Australia
| | - R Mellor
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Qld, Australia
| | - L Heales
- School of Human, Health and Social Science, Division of Physiotherapy, Central Queensland University, Rockhampton, Qld, Australia
| | - A Nordez
- Faculty of Sport Sciences, Laboratory "Movement, Interactions, Performance" (EA 4334), University of Nantes, Nantes, France
| | - F Hug
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Qld, Australia.,Faculty of Sport Sciences, Laboratory "Movement, Interactions, Performance" (EA 4334), University of Nantes, Nantes, France.,Institut Universitaire de France (IUF), Paris, France
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13
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Zhang Q, Cai Y, Hua Y, Shi J, Wang Y, Wang Y. Sonoelastography shows that Achilles tendons with insertional tendinopathy are harder than asymptomatic tendons. Knee Surg Sports Traumatol Arthrosc 2017; 25:1839-1848. [PMID: 27342984 DOI: 10.1007/s00167-016-4197-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 06/07/2016] [Indexed: 01/18/2023]
Abstract
PURPOSE To seek differences of Achilles tendon hardness between insertional tendinopathy (IT) and asymptomatic controls by using computer-assisted quantification on axial-strain sonoelastography (ASE). METHODS The study consisted of 37 non-athletic patients presenting with Achilles tendon pain in one or two tendons. Both tendons were examined clinically. Among the 74 tendons, 16 were diagnosed and categorized into an IT group and 29 into an asymptomatic group. The remaining 29 tendons were excluded due to non-insertional tendinopathy, ruptures, previous surgery or mixed disorders. The tendons in the IT and asymptomatic groups were examined with both ASE and conventional ultrasound. Computer-assisted quantification on ASE was conducted to extract parameters of tendon hardness, including the 20th percentile (H20), median (H50) and skewness (Hsk) of the hardness within tendon, as well as the ratio of the mean hardness within tendon to that outside tendon (Hratio). RESULTS The H20 (p = 0.003), H50 (p = 0.004) and Hratio (p = 0.002) were larger and Hsk (p = 0.001) was smaller at distal thirds of IT tendons than those of asymptomatic tendons. For differentiation between two groups, the Hsk achieved the best value (0.815) of area under the receiver operating characteristic curve, with a sensitivity of 81.3 %, a specificity of 86.2 % and an accuracy of 84.4 %. CONCLUSIONS Computer-assisted quantification on ASE shows that IT tendons are harder than asymptomatic tendons. It might act as a potentially useful technique for identification and risk stratification of IT patients and thus be valuable in day-by-day clinical practice for monitoring IT progression and for evaluating therapeutic effects. LEVEL OF EVIDENCE III.
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Affiliation(s)
- Qi Zhang
- Institute of Biomedical Engineering, Shanghai University, Shanghai, 200444, China
| | - Yehua Cai
- Department of Ultrasound, Huashan Hospital, Fudan University, No. 12, Urumqi Middle Road, Shanghai, 200438, China.
| | - Yinghui Hua
- Department of Sports Medicine, Huashan Hospital, Fudan University, No. 12, Urumqi Middle Road, Shanghai, 200438, China.
| | - Jun Shi
- Institute of Biomedical Engineering, Shanghai University, Shanghai, 200444, China
| | - Yuanyuan Wang
- Department of Electronic Engineering, Fudan University, Shanghai, 200433, China
| | - Yi Wang
- Department of Ultrasound, Huashan Hospital, Fudan University, No. 12, Urumqi Middle Road, Shanghai, 200438, China
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14
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Lee KS, Martin J, Thelen D. Science to Practice: Quantitative US Elastography Can Be Used to Quantify Mechanical and Histologic Tendon Healing in a Rabbit Model of Achilles Tendon Transection. Radiology 2017; 283:311-313. [PMID: 28418825 DOI: 10.1148/radiol.2017170126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Compression-based ultrasonographic (US) elastography is associated with time-dependent mechanical and histologic changes of the healing tendon in a transected rabbit model of the Achilles tendon. This finding will lead to continued development of quantitative US, which can be used to objectively assess a diseased or healing tendon. With advances in the method used, clinical translation of tendon elastography may enable clinicians to diagnose tendon damage and track healing, which should improve both treatment and outcome.
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Affiliation(s)
- Kenneth S Lee
- Department of Radiology University of Wisconsin School of Medicine & Public Health 600 Highland Ave Madison, WI 53792
| | - Jack Martin
- Department of Radiology University of Wisconsin School of Medicine & Public Health 600 Highland Ave Madison, WI 53792
| | - Darryl Thelen
- Department of Radiology University of Wisconsin School of Medicine & Public Health 600 Highland Ave Madison, WI 53792
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Rosskopf AB, Bachmann E, Snedeker JG, Pfirrmann CWA, Buck FM. Comparison of shear wave velocity measurements assessed with two different ultrasound systems in an ex-vivo tendon strain phantom. Skeletal Radiol 2016; 45:1541-51. [PMID: 27631078 DOI: 10.1007/s00256-016-2470-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 08/18/2016] [Accepted: 08/19/2016] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The purpose of this study is to compare the reliability of SW velocity measurements of two different ultrasound systems and their correlation with the tangent traction modulus in a non-static tendon strain model. MATERIALS AND METHODS A bovine tendon was fixed in a custom-made stretching device. Force was applied increasing from 0 up to 18 Newton. During each strain state the tangent traction modulus was determined by the stretcher device, and SW velocity (m/s) measurements using a Siemens S3000 and a Supersonic Aixplorer US machine were done for shear modulus (kPa) calculation. RESULTS A strong significant positive correlation was found between SW velocity assessed by the two ultrasound systems and the tangent traction modulus (r = 0.827-0.954, p < 0.001), yet all SW velocity-based calculations underestimated the reference tissue tangent modulus. Mean difference of SW velocities with the S3000 was 0.44 ± 0.3 m/s (p = 0.002) and with the Aixplorer 0.25 ± 0.3 m/s (p = 0.034). Mean difference of SW velocity between the two US-systems was 0.37 ± 0.3 m/s (p = 0.012). CONCLUSION In conclusion, SW velocities are highly dependent on mechanical forces in the tendon tissue, but for controlled mechanical loads appear to yield reproducible and comparable measurements using different US systems.
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Affiliation(s)
- Andrea B Rosskopf
- Radiology, Orthopedic University Hospital Balgrist, Forchstrasse 340, 8008, Zurich, Switzerland.
- Faculty of Medicine, University of Zurich, Zurich, Switzerland.
| | - Elias Bachmann
- Laboratory for Orthopedic Biomechanics, Orthopedic University Hospital Balgrist, Forchstrasse 340, 8008, Zurich, Switzerland
| | - Jess G Snedeker
- Laboratory for Orthopedic Biomechanics, Orthopedic University Hospital Balgrist, Forchstrasse 340, 8008, Zurich, Switzerland
- Institute for Biomechanics, Swiss Federal Institute of Technology in Zurich (ETHZ), Lengghalde 5, 8092, Zurich, Switzerland
| | - Christian W A Pfirrmann
- Radiology, Orthopedic University Hospital Balgrist, Forchstrasse 340, 8008, Zurich, Switzerland
- Faculty of Medicine, University of Zurich, Zurich, Switzerland
| | - Florian M Buck
- Radiology, Orthopedic University Hospital Balgrist, Forchstrasse 340, 8008, Zurich, Switzerland
- Faculty of Medicine, University of Zurich, Zurich, Switzerland
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Yeh CL, Kuo PL, Gennisson JL, Brum J, Tanter M, Li PC. Shear Wave Measurements for Evaluation of Tendon Diseases. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2016; 63:1906-1921. [PMID: 27824567 DOI: 10.1109/tuffc.2016.2591963] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
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.
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Greenleaf JF, Urban MW. Shear Wave Elastography Applied for the Investigation of Tendon Material Properties. Acad Radiol 2016; 23:1201-3. [PMID: 27575838 DOI: 10.1016/j.acra.2016.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 07/01/2016] [Indexed: 12/17/2022]
Affiliation(s)
- James F Greenleaf
- Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First ST SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, 200 First ST SW, Rochester, MN 55905.
| | - Matthew W Urban
- Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First ST SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, 200 First ST SW, Rochester, MN 55905
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18
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Quantitative ultrasound mapping of regional variations in shear wave speeds of the aging Achilles tendon. Eur Radiol 2016; 27:474-482. [PMID: 27236815 DOI: 10.1007/s00330-016-4409-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/18/2016] [Accepted: 05/13/2016] [Indexed: 12/31/2022]
Abstract
OBJECTIVES Evaluate the effects of aging on healthy Achilles tendon and aponeurosis shear wave speed (SWS), a quantitative metric which reflects tissue elasticity. METHODS Shear wave elastography was used to measure spatial variations in Achilles tendon SWS in healthy young (n = 15, 25 ± 4 years), middle-aged (n = 10, 49 ± 4 years) and older (n = 10, 68 ± 5 years) adults. SWS was separately measured in the free Achilles tendon, soleus aponeurosis and gastrocnemius aponeurosis in resting (R), stretched (dorsiflexed 15° from R) and slack (plantarflexed 15° from R) postures. RESULTS SWS significantly increased with stretch and varied with age in all tendon regions. Slack free tendon SWS was significantly higher in older adults than young adults (p = 0.025). However, stretched soleus aponeurosis SWS was significantly lower in older adults than young adults (p = 0.01). Stretched gastrocnemius aponeurosis SWS was significantly lower in both middle-aged (p = 0.003) and older (p = 0.001) adults, relative to younger adults. CONCLUSION These results suggest that aging alters spatial variations in Achilles tendon elasticity, which could alter deformations within the triceps surae muscle-tendon units, thus affecting injury potential. The observed location- and posture-dependent variations highlight the importance of controlling ankle posture and imaging location when using shear wave approaches clinically to evaluate tendon disorders. KEY POINTS • Shear wave elastography shows promise as a clinical quantitative ultrasound-based technique. • Aging induces location-dependent changes in Achilles tendon shear wave speed. • Spatial and postural dependence necessitates careful integration of this approach clinically.
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Martin JA, Biedrzycki AH, Lee KS, DeWall RJ, Brounts SH, Murphy WL, Markel MD, Thelen DG. In Vivo Measures of Shear Wave Speed as a Predictor of Tendon Elasticity and Strength. ULTRASOUND IN MEDICINE & BIOLOGY 2015. [PMID: 26215492 PMCID: PMC4556570 DOI: 10.1016/j.ultrasmedbio.2015.06.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The purpose of this study was to assess the potential for ultrasound shear wave elastography (SWE) to measure tissue elasticity and ultimate stress in both intact and healing tendons. The lateral gastrocnemius (Achilles) tendons of 41 New Zealand white rabbits were surgically severed and repaired with growth factor coated sutures. SWE imaging was used to measure shear wave speed (SWS) in both the medial and lateral tendons pre-surgery, and at 2 and 4 wk post-surgery. Rabbits were euthanized at 4 wk, and both medial and lateral tendons underwent mechanical testing to failure. SWS significantly (p < 0.001) decreased an average of 17% between the intact and post-surgical state across all tendons. SWS was significantly (p < 0.001) correlated with both the tendon elastic modulus (r = 0.52) and ultimate stress (r = 0.58). Thus, ultrasound SWE is a potentially promising non-invasive technology for quantitatively assessing the mechanical integrity of pre-operative and post-operative tendons.
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Affiliation(s)
- Jack A Martin
- Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin, USA.
| | - Adam H Biedrzycki
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kenneth S Lee
- Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ryan J DeWall
- Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sabrina H Brounts
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - William L Murphy
- Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA; Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Mark D Markel
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Darryl G Thelen
- Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA; Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Abstract
There have been immense technical innovations and broadened clinical applications of ultrasound in the musculoskeletal system over the past 20 years. Specifically with regard to the hand and wrist, the advent of higher resolution transducers and postprocessing software applications have resulted in overall enhanced visualization of soft tissue structures (tendons/ligaments) as well as surface osseous lesions such as subclinical erosions in rheumatoid arthritis. Quantitative ultrasound, using either power Doppler or contrast-enhanced imaging, has become a central outcomes measure used to evaluate and document patient response to treatment in inflammatory arthropathies such as rheumatoid arthritis. This review will summarize the current state of clinical applications of ultrasound in the evaluation of the hand and wrist, with a summary of technical advances and specific applications in rheumatologic conditions.This review was exempt from institutional review board approval.
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Frisch KE, Marcu D, Baer GS, Thelen DG, Vanderby R. Influence of tendon tears on ultrasound echo intensity in response to loading. J Biomech 2014; 47:3813-9. [PMID: 25468301 DOI: 10.1016/j.jbiomech.2014.10.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 09/18/2014] [Accepted: 10/17/2014] [Indexed: 10/24/2022]
Abstract
Acoustoelastic (AE) ultrasound image analysis is a promising non-invasive approach that uses load-dependent echo intensity changes to characterize stiffness of tendinous tissue. The purpose of this study was to investigate whether AE can detect localized changes in tendon stiffness due to partial and full-thickness tendon tears. Ovine infraspinatus tendons with different levels of damage (Intact, 33%, 66% and full thickness cuts initiated on the articular and bursal sides) were cyclically loaded in a mechanical testing system while cine ultrasound images were recorded. The load-induced changes in echo intensity on the bursal and articular side of the tendon were determined. Consistent with AE theory, the undamaged tendons exhibited an increase in echo intensity with tendon loading, reflecting the strain-stiffening behavior of the tissue. In the intact condition, the articular region demonstrated a significantly greater increase in echo intensity during loading than the bursal region. Cuts initiated on the bursal side resulted in a progressive decrease in echo intensity of the adjacent tissue, likely reflecting the reduced load transmission through that region. However, image intensity information was less sensitive for identifying load transmission changes that result from partial thickness cuts initiated on the articular side. We conclude that AE approaches may be useful to quantitatively assess load-dependent changes in tendon stiffness, and that disruption of AE behavior may be indicative of substantial tendon damage.
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Affiliation(s)
- Kayt E Frisch
- Department of Engineering/Dordt College/Sioux Center, Iowa, United States.
| | - David Marcu
- Sauk Prairie Memorial Hospital, Prairie du Sac, Wiscosin, United States.
| | - Geoffrey S Baer
- Department of Orthopedics and Rehabilitation/University of Wisconsin, Madison, Wiscosin, United States.
| | - Darryl G Thelen
- Department of Biomedical Engineering, Department of Mechanical Engineering/University of Wisconsin, Madison, Wiscosin, United States.
| | - Ray Vanderby
- Departments of Orthopedics and Rehabilitation and Biomedical Engineering/University of Wisconsin, Madison, Wiscosin, United States.
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Zhang ZJ, Ng GYF, Lee WC, Fu SN. Changes in morphological and elastic properties of patellar tendon in athletes with unilateral patellar tendinopathy and their relationships with pain and functional disability. PLoS One 2014; 9:e108337. [PMID: 25303466 PMCID: PMC4193737 DOI: 10.1371/journal.pone.0108337] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 08/05/2014] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Patellar tendinopathy (PT) is one of the most common knee disorders among athletes. Changes in morphology and elasticity of the painful tendon and how these relate to the self-perceived pain and dysfunction remain unclear. OBJECTIVES To compare the morphology and elastic properties of patellar tendons between athlete with and without unilateral PT and to examine its association with self-perceived pain and dysfunction. METHODS In this cross-sectional study, 33 male athletes (20 healthy and 13 with unilateral PT) were enrolled. The morphology and elastic properties of the patellar tendon were assessed by the grey and elastography mode of supersonic shear imaging (SSI) technique while the intensity of pressure pain, self-perceived pain and dysfunction were quantified with a 10-lb force to the most painful site and the Victorian Institute of Sport Assessment-patella (VISA-P) questionnaire, respectively. RESULTS In athletes with unilateral PT, the painful tendons had higher shear elastic modulus (SEM) and larger tendon than the non-painful side (p<0.05) or the dominant side of the healthy athletes (p<0.05). Significant correlations were found between tendon SEM ratio (SEM of painful over non-painful tendon) and the intensity of pressure pain (rho = 0.62; p = 0.024), VISA-P scores (rho = -0.61; p = 0.026), and the sub-scores of the VISA-P scores on going down stairs, lunge, single leg hopping and squatting (rho ranged from -0.63 to -0.67; p<0.05). CONCLUSIONS Athletes with unilateral PT had stiffer and larger tendon on the painful side than the non-painful side and the dominant side of healthy athletes. No significant differences on the patellar tendon morphology and elastic properties were detected between the dominant and non-dominant knees of the healthy control. The ratio of the SEM of painful to non-painful sides was associated with pain and dysfunction among athletes with unilateral PT.
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Affiliation(s)
- Zhi Jie Zhang
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
- Guangdong-Hongkong Joint Sports Rehabilitation and Research Center, Guangdong Provincial Work Injury Rehabilitation Hospital, Guangzhou, China
| | - Gabriel Yin-fat Ng
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Wai Chun Lee
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Siu Ngor Fu
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
- * E-mail:
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23
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DeWall RJ, Slane LC, Lee KS, Thelen DG. Spatial variations in Achilles tendon shear wave speed. J Biomech 2014; 47:2685-92. [PMID: 24933528 DOI: 10.1016/j.jbiomech.2014.05.008] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 05/07/2014] [Accepted: 05/12/2014] [Indexed: 11/17/2022]
Abstract
Supersonic shear imaging (SSI) is an ultrasound imaging modality that can provide insight into tissue mechanics by measuring shear wave propagation speed, a property that depends on tissue elasticity. SSI has previously been used to characterize the increase in Achilles tendon shear wave speed that occurs with loading, an effect attributable to the strain-stiffening behavior of the tissue. However, little is known about how shear wave speed varies spatially, which is important, given the anatomical variation that occurs between the calcaneus insertion and the gastrocnemius musculotendon junction. The purpose of this study was to investigate spatial variations in shear wave speed along medial and lateral paths of the Achilles tendon for three different ankle postures: resting ankle angle (R, i.e. neutral), plantarflexed (P; R - 15°), and dorsiflexed (D; R+15°). We observed significant spatial and posture variations in tendon shear wave speed in ten healthy young adults. Shear wave speeds in the Achilles free tendon averaged 12 ± 1.2m/s in a resting position, but decreased to 7.2 ± 1.8m/s with passive plantarflexion. Distal tendon shear wave speeds often reached the maximum tracking limit (16.3m/s) of the system when the ankle was in the passively dorsiflexed posture (+15° from R). At a fixed posture, shear wave speeds decreased significantly from the free tendon to the gastrocnemius musculotendon junction, with slightly higher speeds measured on the medial side than on the lateral side. Shear wave speeds were only weakly correlated with the thickness and depth of the tendon, suggesting that the distal-to-proximal variations may reflect greater compliance in the aponeurosis relative to the free tendon. The results highlight the importance of considering both limb posture and transducer positioning when using SSI for biomechanical and clinical assessments of the Achilles tendon.
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Affiliation(s)
- Ryan J DeWall
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, USA; Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA.
| | - Laura C Slane
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Kenneth S Lee
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Darryl G Thelen
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA; Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
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