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Background: Hepatitis C virus (HCV) is a major cause of chronic liver disease, in which liver stiffness increases. Liver stiffness measurements (LSM) are therefore essential in diagnosing liver diseases and predicting disease development. The study objective was to perform a comprehensive prospective assessment of the liver before, after and 4 years after treatment for HCV, including an assessment of the long-term outcome of fibrosis, steatosis and inflammation. Methods and findings: Patients eligible for HCV treatment were included prospectively in 2018 (n = 47). Liver stiffness was measured using transient elastography and 2D shear-wave elastography (SWE). Blood tests, B-mode ultrasound (US) and SWE, were performed before, after (end of treatment [EOT]), 3 months after (EOT3) and 4 years after treatment (4Y). At the final visit, we added attenuation imaging and shear-wave dispersion slope (SWDS) measurements to assess steatosis and inflammation. Three months after treatment, the sustained virologic response rate was 93%. The median liver stiffness for baseline, EOT, EOT3 and 4Y was 8.1, 5.9, 5.6 and 6.3 kPa, respectively. There was a significant reduction in liver stiffness from baseline to EOT, and from EOT to EOT3. After 4 years, the mean attenuation coefficient (AC) was 0.58 dB/cm/MHz, and the mean SWDS value was 14.3 (m/s)/kHz. Conclusion: The treatment for HCV was highly effective. Measurements of liver stiffness decreased significantly after treatment and remained low after 4 years. AC measurements indicated low levels of liver steatosis. Shear-wave dispersion values indicated inflammation of the liver, but the clinical implication is undetermined and should be explored in larger studies. Clinicaltrials.gov: NCT03434470 Abbreviations: AC: attenuation coefficient; APRI: aspartate aminotransferase to platelet ratio index; ATI: attenuation imaging; cACLD: compensated advanced chronic liver disease; CAP: controlled attenuation parameter; FIB-4: Fibrosis-4 Index for liver fibrosis; HCC: hepatocellular carcinoma; LSM: liver stiffness measurement; NAFLD: non-alcoholic fatty liver disease; NASH: non-alcoholic steatohepatitis; SWDS: shear-wave dispersion slope; SWE: shear-wave elastography; US: ultrasound [ABSTRACT FROM AUTHOR]

Introduction: We sought to determine the effectiveness and utility of two-dimensional shear-wave sonoelastography (2D-SW-SE) in the diagnosis and postoperative follow-up of infantile hypertrophic pyloric stenosis (IHPS). Materials and Methods: Twenty-three infants were included in the study, 13 in the IHPS group and 10 in the control group (CG). Preoperative B-mode ultrasonography measurements (longitudinal length and single-wall thickness of the pylorus) and 2D-SW-SE measurements (pylorus tissue stiffness and shear-wave propagation speed) were compared between the groups. The infants with IHPS then underwent Ramstedt pyloromyotomy and were invited for follow-ups on the tenth day and the first, third, and sixth months postoperatively. Measurements taken at the follow-ups were compared with the preoperative values. Results: No differences were found between the groups regarding age, gender, body weight, or week of birth. The pyloric lengths in the IHPS group were longer than in the CG (p < 0.001), and the single-wall thicknesses were thicker (p < 0.001). The pylorus in the IHPS group was four times stiffer than in the CG (27.4 kPa versus 7.66 kPa), and the shear-wave propagation speed in the tissue was higher (1.34 m/s versus 2.69 m/s; p < 0.001). Both values decreased over time in the IHPS group and were normal by the third postoperative month. Conclusions: 2D-SW-SE can be used as an assistive imaging tool alongside B-mode ultrasound for diagnosing IHPS. It can also be used to identify inadequate surgery by detecting whether the pyloric tissue has softened at follow-up. [ABSTRACT FROM AUTHOR]

Introduction and hypothesis: This study is aimed at developing and validating a new integral parameter, the Biomechanical Integrity score (BI-score) of the female pelvic floor for stress urinary incontinence conditions. Methods: A total of 130 subjects were included in the observational cohort study; 70 subjects had normal pelvic floor conditions, and 60 subjects had stress urinary incontinence (SUI). A Vaginal Tactile Imager (VTI) was used to acquire and automatically calculate 52 biomechanical parameters for eight VTI test procedures (probe insertion, elevation, rotation, Valsalva maneuver, voluntary muscle contractions in two planes, relaxation, and reflex contraction). Statistical methods were applied (t test, correlation) to identify the VTI parameters sensitive to the pelvic SUI conditions. Results: Twenty-seven parameters were identified as statistically sensitive to SUI development. They were subdivided into five groups to characterize tissue elasticity (group 1), pelvic support (group 2), pelvic muscle contraction (group 3), involuntary muscle relaxation (group 4), and pelvic muscle mobility (group 5). Every parameter was transformed to its standard deviation units using the dataset for normal pelvic conditions, similar to the T-score for bone density. Linear combinations with specified weights led to the composition of five component parameters for groups 1–5 and to the BI-score in standard deviation units. The p value for the BI-score has p = 4.0 × 10–28 for SUI versus normal conditions. Conclusions: Quantitative transformations of the pelvic tissues, support structures, and functions under diseased conditions may be studied with the SUI BI-score in future research and clinical applications. [ABSTRACT FROM AUTHOR]

This study addresses a crucial necessity in the field of noninvasive liver fibrosis diagnosis by introducing the concept of continuous shear wave elastography (C-SWE), utilizing an external vibration source and color Doppler imaging. However, an application of C-SWE to assess liver elasticity, a deep region within the human body, arises an issue of signal instability in the obtained data. To tackle this challenge, this work proposes a method involving the acquisition of multiple frames of datasets, which are subsequently compressed. Furthermore, the proposed frame-to-frame equalization method compensates discrepancies in the initial phase that might exist among multiple-frame datasets, thereby significantly enhancing signal stability. The experimental validation of this approach encompasses both phantom tests and in vivo experiments. In the phantom tests, the proposed technique is validated through a comparison with the established shear wave elastography (SWE) technique. The results demonstrate a remarkable agreement, with an error in shear wave velocity of less than 4.2%. Additionally, the efficacy of the proposed method is confirmed through in vivo tests. As a result, the stabilization of observed shear waves using the frame-to-frame equalization technique exhibits promising potential for accurately assessing human liver elasticity. These findings collectively underscore the viability of C-SWE as a potential diagnostic instrument for liver fibrosis. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to (1) assess the precision and reproducibility of color Doppler shear wave imaging (CD SWI) by comparing it with shear wave elastography (SWE) via elasticity phantom measurements, and (2) investigate the potential clinical applications of CD SWI in the upper limb muscles by assessing the reproducibility of skeletal muscle elasticity evaluations. Methods: Four elastography phantoms of different stiffness (6.0–7.5 wt%) were used to assess the precision and reproducibility of CD SWI (compared with SWE) at depths. Typical upper limb muscles of 24 men were also assessed for this comparison. Results: At superficial depths (0–2 cm), the phantom measurements obtained using CD SWI and SWE were similar at all levels of stiffness. Furthermore, both methods were highly reliable, with almost perfect intra- and inter-operator reliabilities. At greater depths (2–4 cm), measurements obtained using both methods were similar at all stiffness levels. Although standard deviations (SDs) of the phantom measurements obtained using both methods at lower stiffness were similar, those at higher stiffness were different. The SD of the CD SWI measurements was < 50% of that of the SWE measurements. However, both methods were highly reliable in the phantom test, with almost perfect intra- and inter-operator reliabilities. The intra- and inter-operator reliabilities of the shear wave velocity measurements for typical muscles of the upper limbs were also substantial in clinical settings. Conclusion: CD SWI is a valid method for measuring elasticity, with precision and reliability as high as those of SWE. [ABSTRACT FROM AUTHOR]

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

Ultrasound shear wave elastography can be used to characterize mechanical properties of unstressed tissue by measuring shear wave velocity (SWV), which increases with increasing tissue stiffness. Measurements of SWV have often been assumed to be directly related to the stiffness of muscle. Some have also used measures of SWV to estimate stress, since muscle stiffness and stress covary during active contractions, but few have considered the direct influence of muscle stress on SWV. Rather, it is often assumed that stress alters the material properties of muscle, and in turn, shear wave propagation. The objective of this study was to determine how well the theoretical dependency of SWV on stress can account for measured changes of SWV in passive and active muscles. Data were collected from six isoflurane-anesthetized cats; three soleus muscles and three medial gastrocnemius muscles. Muscle stress and stiffness were measured directly along with SWV. Measurements were made across a range of passively and actively generated stresses, obtained by varying muscle length and activation, which was controlled by stimulating the sciatic nerve. Our results show that SWV depends primarily on the stress in a passively stretched muscle. In contrast, the SWV in active muscle is higher than would be predicted by considering only stress, presumably due to activation-dependent changes in muscle stiffness. Our results demonstrate that while SWV is sensitive to changes in muscle stress and activation, there is not a unique relationship between SWV and either of these quantities when considered in isolation. [ABSTRACT FROM AUTHOR]

The mechanical properties and structure alteration (e.g., layer morphology and thickness) of the oesophagus wall can reflect its pathological conditions. Hence, quantitative measurement of the above-mentioned properties can play a significant role in aiding the disease diagnosis in clinical application. As a fast and non-invasive imaging modality, Optical coherence tomography (OCT) and vibrational elastography can provide high resolution (<10 µm) structural and mechanical mapping of soft tissue. This study is a preliminary study to explore the potential of OCT and VOCE to evaluate both structural and mechanical properties of the oesophagus wall. Jn total, 52 oesophageal tissue samples were acquired from seven human Thiel-embalmed cadavers and were examined by the vibrational OCE. Both the OCT structure image and quantitative elasticity of each sample layer were obtained. In the OCT structure image, the averaged thickness for each sample layer was measured and corresponded with the histological image. Lamina propria has the largest thickness of 158.14 ± 8.75 µm, submucosa is the thinnest with a thickness of 143.19 ± 10.11 µm, and the thickness of muscularis mucosa is 149.49 ± 10.85 µm. Averaged intensity of back-scattered light from each sample layer was evaluated. Intensity of lamina propria layer, muscularis mucosa layer, and submucosa layer have an average value of 79.27 ± 0.51 dB, 69.83 ± 0.56 dB, and 76.10 ± 0.55 dB, respectively. The quantitative elasticity of each sample layer was evaluated in OCE. Elasticity of the lamina propria layer, muscularis mucosa layer, and submucosa layer were estimated as 115.64 ± 8.80 kPa, 60.28 ± 5.27 kPa, and 205.25 ± 19.03 kPa, respectively. The quantitative elasticity results obtained by vibrational OCE corresponded with the collagen distribution trend in each sample layer. This study demonstrates the ability of OCT and vibrational OCE in the characterisation and quantitative evaluation of human cadaver oesophagus wall-structure properties and mechanical properties. The feasibility of applying OCT and vibrational OCE in clinical diagnosis of oesophageal disease is also discussed. [ABSTRACT FROM AUTHOR]

Vaginal Tactile Imaging is a novel technology that creates a visual map of the female pelvic floor based on its biomechanical properties. The vaginal tactile imager is a medical device built on this technology to assist clinicians in diagnosis and prognosis of pelvic floor conditions and treatment from detailed characterization of vaginal tissue elasticity, pelvic support and function. This information is presented in the form of tactile images, a format in which pressure mapping is combined with spatial dimensions. The dynamic pressure patterns are combined using two opposing areas along the vaginal walls during Valsalva maneuver, voluntary and reflex muscle contraction, and involuntary relaxation. Based on these measurements, the biomechanical integrity score of the pelvic floor was developed and introduced to facilitate clinical interpretation of the complex data. This article begins with a brief overview of the tactile imaging for a broad spectrum of applications, clinical research findings and their respective impact. Then the article focuses on the evolution of the technology and its progressive development for the female pelvic floor disorders characterization and diagnostics, including evaluation of surgical intervention. Finally, future possibilities for tactile imaging are discussed, including applications in obstetrics and a fusion with ultrasound imaging. [ABSTRACT FROM AUTHOR]

Objective: Ultrasound (US) shear wave elasticity imaging (SWEI) is a mature technique for diagnosing the elasticity of isotropic tissues. However, the elasticity of anisotropic tissues, such as muscle and tendon, cannot be diagnosed correctly using SWEI because the shear wave velocity (SWV) varies with tissue fiber orientations. Recently, SWEI has been studied for measuring the anisotropic properties of muscles by rotating the transducer; however, this is difficult for clinical practice. Methods: In this study, a novel dual-direction shear wave imaging (DDSWI) technique was proposed for visualizing the mechanical anisotropy of muscles without rotation. Longitudinal and transverse shear waves were created by a specially designed external vibrator and supersonic pushing beam, respectively; the SWVs were then tracked using ultrafast US imaging. Subsequently, the SWV maps of two directions were obtained at the same scanning cross section, and the mechanical anisotropy was represented as the ratio between them at each pixel. Results: The performance of DDSWI was verified using a standard phantom, and human experiments were performed on the gastrocnemius and biceps brachii. Experimental results of phantom revealed DDSWI exhibited a high precision of <0.81% and a low bias of <3.88% in SWV measurements. The distribution of anisotropic properties in muscle was visualized with the anisotropic ratios of 1.54 and 2.27 for the gastrocnemius and biceps brachii, respectively. Conclusion: The results highlight the potential of this novel anisotropic imaging in clinical applications because the conditions of musculoskeletal fiber orientation can be easily and accurately evaluated in real time by DDSWI. [ABSTRACT FROM AUTHOR]

Purpose: The use of ultrasound (US) elastography to assess the pancreas is subject to serious limitations, and it is not easy to perform US elastography for the pancreas with satisfactory and reproducible accuracy. The aim of our study was to show the normal pancreatic stiffness values with shear wave elastography (SWE) and to evaluate the pancreatic tissue stiffness at two different respiratory phases. Methods: Sixty-three subjects were included in the study. Median values of pancreatic stiffness were recorded. Values during deep inspiration and free breathing were compared. Results: The stiffness values of the pancreatic tissue measured during deep inspiration breath holds and during free breathing were 5.70 ± 1.74 kPa and 4.15 ± 1.70 kPa, respectively. It was found that the values of pancreatic tissue stiffness measured during deep inspiration were statistically significantly higher than those measured during physiological breathing (p < 0.001). Conclusions: Because of the reference value differences between different ultrasound elastography devices, it is important to know the reference ranges of normal pancreatic stiffness according to the device, in order to distinguish possible pathologies. In addition, the variability of pancreatic stiffness measurements with respiratory phases should be considered in clinical applications. [ABSTRACT FROM AUTHOR]

Introduction and Hypothesis: The aim of this study is to develop and validate a new integral parameter, the Biomechanical Integrity score (BI-score), for the characterization of the female pelvic floor. Methods: A total of 253 subjects with normal and pelvic organ prolapse (POP) conditions were included in the multi-site observational, case-control study; 125 subjects had normal pelvic floor conditions, and 128 subjects had POP stage II or higher. A Vaginal Tactile Imager (VTI) was used to acquire and automatically calculate 52 biomechanical parameters for eight VTI test procedures (probe insertion, elevation, rotation, Valsalva maneuver, voluntary muscle contractions in two planes, relaxation, and reflex contraction). Statistical methods were applied (t-test, correlation) to identify the VTI parameters sensitive to the pelvic conditions. Results: Twenty-six parameters were identified as statistically sensitive to POP development. They were subdivided into five groups to characterize (1) tissue elasticity, (2) pelvic support, (3) pelvic muscle contraction, (4) involuntary muscle relaxation, and (5) pelvic muscle mobility. Every parameter was transformed to its standard deviation units against the patient age similar to T-score for bone density. Linear combinations with specified weights led to the composition of five component parameters for groups (1)–(5) and the BI-score in standard deviation units. The p-value for the BI-score has p = 4.3 × 10−31 for POP versus normal conditions. A reference BI-score curve against age for normal pelvic floor conditions was defined. Conclusions: Quantitative transformations of the pelvic tissues, support structures, and functions under diseased conditions may be studied with the BI-score in future research and practical applications. [ABSTRACT FROM AUTHOR]

The mechanical properties and structure alteration (e.g., layer morphology and thickness) of the oesophagus wall can reflect its pathological conditions. Hence, quantitative measurement of the above-mentioned properties can play a significant role in aiding the disease diagnosis in clinical application. As a fast and non-invasive imaging modality, Optical coherence tomography (OCT) and vibrational elastography can provide high resolution (

Purpose: Tissue elasticity can be measured and mapped using color Doppler elastography. In a previous study, a binary pattern of shear waves was observed using a color flow imaging (CFI) system with matched pulse Doppler packet size as well as shear wave frequency and displacement condition. In the present study, we demonstrate the possibility of mapping shear wave velocity and resolving phantom elasticity using any commercial ultrasound machine without fulfilling that condition. Methods: We derive a relation between Doppler autocorrelator integration time and the estimated flow velocity. The underlying principles behind the shear wave shadows captured by a typical modern ultrasound machine are investigated. The ultrasound machine measurement preset is calibrated to remove the effect of transducer array scanning delay in modifying the appearing wavenumber and thus correct the measurement error. Results: The method was used to successfully measure the elasticity of a biological tissue-mimicking phantom and distinguish a stiff phantom from a soft phantom. Conclusion: Using this method, the elasticity of a biological tissue-mimicking phantom can be recovered with less strict constraint. As a result, it provides more flexibility to be implemented in common ultrasound machines. This method may be practically used to help identify tissue stiffness-related disease. [ABSTRACT FROM AUTHOR]

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Arian Ansardamavandi,1 Mohammad Tafazzoli-Shadpour,1 Ramin Omidvar,2 Fatemeh Nili3 1Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran; 2Faculty of Biology, Centre for Biological Signalling Studies (BIOSS), Albert Ludwigs University Freiburg, Freiburg, Germany; 3Department of Pathology, Tehran University of Medical Sciences, Tehran, IranCorrespondence: Mohammad Tafazzoli-ShadpourAmirkabir University of Technology, No. 350, Hafez Ave, Valiasr Square, Tehran, IranTel +98 02164542385Email Tafazoli@aut.ac.irBackground: Different diseases affect both mechanical and chemical features of the involved tissue, enhancing the symptoms.Methods: In this study, using atomic force microscopy, we mechanically characterized human ovarian tissues with four distinct pathological conditions: mucinous, serous, and mature teratoma tumors, and non-tumorous endometriosis. Mechanical elasticity profiles were quantified and the resultant data were categorized using K-means clustering method, as well as fuzzy C-means, to evaluate elastic moduli of cellular and non-cellular parts of diseased tissues and compare them among four disease conditions. Samples were stained by hematoxylin–eosin staining to further study the content of different locations of tissues.Results: Pathological state vastly influenced the mechanical properties of the ovarian tissues. Significant alterations among elastic moduli of both cellular and non-cellular parts were observed. Mature teratoma tumors commonly composed of multiple cell types and heterogeneous ECM structure showed the widest range of elasticity profile and the stiffest average elastic modulus of 14 kPa. Samples of serous tumors were the softest tissues with elastic modulus of only 400 Pa for the cellular part and 5 kPa for the ECM. Tissues of other two diseases were closer in mechanical properties as mucinous tumors were insignificantly stiffer than endometriosis in cellular part, 1300 Pa compared to 1000 Pa, with the ECM average elastic modulus of 8 kPa for both.Conclusion: The higher incidence of carcinoma out of teratoma and serous tumors may be related to the intense alteration of mechanical features of the cellular and the ECM, serving as a potential risk factor which necessitates further investigation.Keywords: ovarian tumors, tissue elasticity, atomic force microscopy, cellular and extra cellular matrix components

Abstract Background This randomized controlled trial explored the practicality and effectiveness of a novel tool-assisted self-help device, one that combines vibrational oscillation, leverage, and the shearing effect from the edges, for promoting meaningful changes in key biomechanical tissue indices and related parameters. Methods One hundred and thirteen male breakdancers were randomized to an intervention or control group. Individuals assigned to the intervention group performed the self-help treatment on the quadriceps and the iliotibial band of their right thighs for 8 min, while individuals assigned to the control condition merely sat quietly during this period. Various primary outcome measures (e.g., elasticity, stiffness, range of motion, pain pressure threshold sensitization, and blood flow) were assessed before and after the intervention for each participant, with position and posture being standardized throughout. Subjective sensations and a measure selected to assess for potential experimental demand effects, serving as secondary measures, were also administered pre- to post-treatment. Results Stiffness was significantly reduced for both structures (p

Oral cancer has consistently been ranked among the top ten cancers in terms of mortality with five year survival rates being among the lowest for all major cancers. Consequently, great efforts are being made to develop new diagnostic tools that can enable early detection in a clinical setting. In this study, we report on the design and development of a novel pen-like handheld device, with a miniaturized tactile sensor mounted on the front-end and integrated with a portable back-end readout module. The device can be used for tissue palpation in the oral cavity and obtain quantitative information regarding the elasticity of oral lesions and abnormalities, thus eliminating the need for manual palpation by the clinician. The sensing mechanism of the proposed tactile sensor is based on the two-spring model and employs two components with varying stiffness values, namely a hard copper ball embedded in a soft elastomeric packaging. The differential voltage output of the piezoelectric sensing film corresponding to the two components can provide information regarding the elasticity of the tissue under contact. To simulate feasibility of the tactile sensor in differentiating tissue elasticity, we have contacted the sensor with different elastomeric silicone materials under the same applied force. The experiments confirmed that the sensor response could be used to differentiate five silicones with varying Young’s moduli ranging from 0.2 to 3.1 MPa and a corresponding Shore hardness of 2 to 56 Shore A. A two-stage linear trend was observed with a sensitivity of 0.356/MPa for softer silicones (2 ~ 9 Shore A) and 0.059/MPa for harder silicones (24 ~ 56 Shore A). Furthermore, the portable readout module that we have developed can analyze the data from the tactile sensor and transmit it wirelessly via Bluetooth for cloud computing. The proposed device is easy-to-use in general clinical settings and could enable early detection and improved prognosis of oral cancer. [ABSTRACT FROM AUTHOR]

Clinical assessments for many musculoskeletal disorders involve evaluation of muscle stiffness, although it is not yet possible to obtain quantitative estimates from individual muscles. Ultrasound elastography can be used to estimate the material properties of unstressed, homogeneous, and isotropic materials by tracking the speed of shear wave propagation; these waves propagate faster in stiffer materials. Although elastography has been applied to skeletal muscle, there is little evidence that shear wave velocity (SWV) can directly estimate muscle stiffness since this tissue violates many of the assumptions required for there to be a direct relationship between SWV and stiffness. The objective of this study was to evaluate the relationship between SWV and direct measurements of muscle force and stiffness in contracting muscle. Data were collected from six isofluraneanesthetized cats. We measured the short-range stiffness in the soleus via direct mechanical testing in situ and SWV via ultrasound imaging. Measurements were taken during supramaximal activation at optimum muscle length, with muscle temperature varying between 26°C and 38°C. An increase in temperature causes a decrease in muscle stiffness at a given force, thus decoupling the tension-stiffness relationship normally present in muscle. We found that increasing muscle temperature decreased active stiffness from 4.0 ± 0.3 MPa to 3.3 ± 0.3 MPa and SWV from 16.9 ± 1.5 m/s to 15.9 ± 1.6 m/s while force remained unchanged (mean ± SD). These results demonstrate that SWV is sensitive to changes in muscle stiffness during active contractions. Future work is needed to determine how this relationship is influenced by changes in muscle structure and tension. [ABSTRACT FROM AUTHOR]

Dynamic optical coherence elastography (OCE) tracks elastic wave propagation speed within tissue, enabling quantitative three-dimensional imaging of the elastic modulus. We show that propagating mechanical waves are mode converted at interfaces, creating a finite region on the order of an acoustic wavelength where there is not a simple one-to-one correspondence between wave speed and elastic modulus. Depending on the details of a boundary's geometry and elasticity contrast, highly complex propagating fields produced near the boundary can substantially affect both the spatial resolution and contrast of the elasticity image. We demonstrate boundary effects on Rayleigh waves incident on a vertical boundary between media of different shear moduli. Lateral resolution is defined by the width of the transition zone between two media and is the limit at which a physical inclusion can be detected with full contrast. We experimentally demonstrate results using a spectraldomain OCT system on tissue-mimicking phantoms, which are replicated using numerical simulations. It is shown that the spatial resolution in dynamic OCE is determined by the temporal and spatial characteristics (i.e., bandwidth and spatial pulse width) of the propagating mechanical wave. Thus, mechanical resolution in dynamic OCE inherently differs from the optical resolution of the OCT imaging system. [ABSTRACT FROM AUTHOR]

Strain ratio measurements of tendons vary because of the reference tissue selection. The main purpose of this study is to highlight, in detail, the numeric variability attributable to the use of various reference materials on strain ratio measurements of patellar and Achilles tendons. Measurements were performed at the proximal, middle and distal thirds of the patellar and Achilles tendons on the dominant site of healthy volunteers. A total of 3 references were used: the Hoffa's fat pad for the patellar tendon, the Kager's fat pad for the Achilles tendon, subcutaneous tissue and Aquaflex gel pads (Parker Laboratories, Fairfield, NJ, USA) for both tendons. Although the same methods were used by the same physician for each tendon site on repeated measurements, strain ratio values had numeric variability with various reference materials in each measurement. Therefore, comparison of numeric strain ratio results of various studies with various reference materials could confuse the clinical interpretations of these numeric data, and, using a reference material with standard stiffness like Aquaflex ultrasound gel pads, should be considered by verifying these results with further studies. [ABSTRACT FROM AUTHOR]

Numerous eye diseases are linked to biomechanical dysfunction of the retina. However, the underlying forces are almost impossible to quantify experimentally. Here, we show how biomechanical properties of adult neuronal tissues such as porcine retinae can be investigated under tension in a home-built tissue stretcher composed of nanostructured TiO2 scaffolds coupled to a self-designed force sensor. The employed TiO2 nanotube scaffolds allow for organotypic long-term preservation of adult tissues ex vivo and support strong tissue adhesion without the application of glues, a prerequisite for tissue investigations under tension. In combination with finite element calculations we found that the deformation behavior is highly dependent on the displacement rate which results in Young’s moduli of (760–1270) Pa. Image analysis revealed that the elastic regime is characterized by a reversible shear deformation of retinal layers. For larger deformations, tissue destruction and sliding of retinal layers occurred with an equilibration between slip and stick at the interface of ruptured layers, resulting in a constant force during stretching. Since our study demonstrates how porcine eyes collected from slaughterhouses can be employed for ex vivo experiments, our study also offers new perspectives to investigate tissue biomechanics without excessive animal experiments.

X-ray mammography is commonly used to scan cancer or tumors in breast using low dose x-rays. But mammograms suffer from low contrast problem. The breast is compressed in mammography to reduce x-ray scattering effects. As tumors are stiffer than normal tissues, they undergo smaller deformation under compression. Therefore, image intensity at tumor region may change less than the background tissues. In this study, we try to find out compression induced contrast from multiple mammographic images of tumorous breast phantoms taken with different compressions. This is an extended work of our previous simulation study with experiment and more analysis. We have used FEM models for synthetic phantom and constructed a phantom using agar and n-propanol for simulation and experiment. The x-ray images of deformed phantoms have been obtained under three compression steps and a non-rigid registration technique has been applied to register these images. It is noticeably observed that the image intensity changes at tumor are less than those at surrounding which induce a detectable contrast. Addition of this compression induced contrast to the simulated and experimental images has improved their original contrast by a factor of about 1.4

Résumé Objectif de l’étude Les « volumateurs » à base d’acide hyaluronique réticulé sont la référence pour traiter les rides superficielles, les plis profonds et les creux liés au vieillissement du visage. Cette étude a pour objectif d’évaluer, en plus des effets d’augmentation de volume, les effets sur la souplesse et l’élasticité des tissus cicatriciels, de 3 acides hyaluroniques réticulés commercialisés (dosés à 15 mg/mL, 17,5 mg/mL et 20 mg/mL), après chirurgie réparatrice chez des patients atteints d’anomalies faciales congénitales ou acquises. Patients et méthode Nous avons débuté l’usage des acides hyaluroniques réticulés en gel injectable dans ces indications en 2013 et avons réalisé à ce jour 46 séances d’injections, chez 32 patients âgés de 13–32 ans. Les résultats ont été évalués par le patient lui-même et par un chirurgien, environ 15 jours après les injections et 6–18 mois plus tard. Résultats Les acides hyaluroniques réticulés ont apporté des résultats morphologiques et esthétiques très subtils, en complément des interventions chirurgicales, avec un niveau de satisfaction élevé des patients. Dans les zones cicatricielles fibreuses, la première session d’injections améliorait la souplesse et l’élasticité ; la seconde session améliorait les volumes. Les acides hyaluroniques sont capables de restaurer simultanément les volumes manquants et l’élasticité des tissus cicatriciels. Conclusion Au-delà de leur fonction de volumateur, un second effet des acides hyaluroniques réticulés est démontré cliniquement : l’augmentation de la souplesse et de l’élasticité des tissus cicatriciel fibreux. Plusieurs études expérimentales corroborent nos résultats en démontrant qu’ils modifient la composition des matrices extra cellulaires notamment en stimulant la production d’élastine et de collagène. Summary Background Cross-linked hyaluronic acid-based fillers have gained rapid acceptance for treating facial wrinkles, deep tissue folds and sunken areas due to aging. This study evaluates, in addition to space-filling properties, their effects on softness and elasticity as a secondary effect, following injection of 3 commercially available cross-linked hyaluronic acid-based fillers (15 mg/mL, 17,5 mg/mL and 20 mg/mL) in patients presenting with congenital or acquired facial malformations. Patients et methods We started injecting gels of cross-linked hyaluronic acid-based fillers in those cases in 2013; we performed 46 sessions of injections in 32 patients, aged from 13–32. Clinical assessment was performed by the patient himself and by a plastic surgeon, 15 days after injections and 6–18 months later. Results Cross-linked hyaluronic acid-based fillers offered very subtle cosmetic results and supplemented surgery with a very high level of satisfaction of the patients. When injected in fibrosis, the first session enhanced softness and elasticity; the second session enhanced the volume. Cross-linked hyaluronic acid-based fillers fill sunken areas and better softness and elasticity of scar tissues. Conclusion In addition to their well-understood space-filling function, as a secondary effect, the authors demonstrate that cross-linked hyaluronic acid-based fillers improve softness and elasticity of scarring tissues. Many experimental studies support our observations, showing that cross-linked hyaluronic acid stimulates the production of several extra-cellular matrix components, including dermal collagen and elastin. [ABSTRACT FROM AUTHOR]

Background: This randomized controlled trial explored the practicality and effectiveness of a novel tool-assisted self-help device, one that combines vibrational oscillation, leverage, and the shearing effect from the edges, for promoting meaningful changes in key biochemical tissue indices and related parameters. Methods: One hundred and thirteen male breakdancers were randomized to an intervention or control group. Individuals assigned to the intervention group performed the self-help treatment on the quadriceps and the iliotibial band of their right thighs for 8 min, while individuals assigned to the control condition merely sat quietly during this period. Various primary outcome measures (e.g., elasticity, stiffness, range of motion, pain pressure threshold sensitization, and blood flow) were assessed before and after the intervention for each participant, with position and posture being standardized throughout. Subjective sensations and a measure selected to assess for potential experimental demand effects, serving as secondary measures, were also administered pre- to post-treatment. Results: Stiffness was significantly reduced for both structures (p < 0.001), elasticity and flexibility of the quadriceps were increased significantly (p < 0.001 for each), sensitization was significantly lessened (p < 0.001), and local temperatures increased to a significant degree as well (p < 0.001) when comparing change scores following application of the self-help tool on the treated thighs to those on the untreated thighs. Participants using the self-help tool reported their treated leg as being more relaxed, light, and stable. Conclusions: The vibro-shearing manipulation with a muscle-fascia tool resulted in significant improvements in various objective mechanical tissue properties, range of motion, and pain desensitization in healthy, well-conditioned dancers. These promising effects for a new tool-assisted self-treatment indicate further basic investigations are warranted, as are pilot investigations with patient populations. [ABSTRACT FROM AUTHOR]

Copyright of Polish Journal of Sports Medicine / Medycyna Sportowa is the property of Agencja Wydawnicza Medsportpress Sp. z o. o. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Optical coherence elastography (OCE) can provide clinically valuable information based on local measurements of tissue stiffness. Improved light sources and scanning methods in optical coherence tomography (OCT) have led to rapid growth in systems for high-resolution, quantitative elastography using imaged displacements and strains within soft tissue to infer local mechanical properties. We describe in some detail the physical processes underlying tissue mechanical response based on static and dynamic displacement methods. Namely, the assumptions commonly used to interpret displacement and strain measurements in terms of tissue elasticity for static OCE and propagating wave modes in dynamic OCE are discussed with the ultimate focus on OCT system design for ophthalmic applications. Practical OCT motion-tracking methods used to map tissue elasticity are also presented to fully describe technical developments in OCE, particularly noting those focused on the anterior segment of the eye. Clinical issues and future directions are discussed in the hope that OCE techniques will rapidly move forward to translational studies and clinical applications. [ABSTRACT FROM AUTHOR]

Objectives: To examine the role of quantitative real-time elastography (RTE) features on differentiation between high-risk prostate cancer (PCA) and non-high-risk prostatic diseases in the initial transperineal biopsy setting. Methods: We retrospectively included 103 patients with suspicious PCA who underwent both RTE and initial transperineal prostate biopsy. Patients were grouped into high-risk and non-high-risk categories according to the D'Amico's risk stratification. With computer assistance based on MATLAB programming, three features were extracted from RTE, i.e., the median hardness within peripheral gland (PG) ( H ), the ratio of the median hardness within PG to that outside PG ( H ), and the ratio of the hard area within PG to the total PG area ( H ). A multiple regression model incorporating an RTE feature, age, transrectal ultrasound finding, and prostate volume was used to identify markers for high-risk PCA. Results: Forty-seven patients (45.6%) were diagnosed with PCA and 34 (33.0%) were diagnosed with high-risk PCA. Three RTE features were all statistically higher in high-risk PCA than in non-high-risk diseases ( p < 0.001), indicating that the PGs in high-risk PCA patients were harder than those in non-high-risk patients. A high H , high age, and low prostate volume were found to be independent markers for PCAs ( p < 0.05), among which the high H was the only independent marker for high-risk PCAs ( p = 0.012). When predicting high-risk PCAs, the multiple regression achieved an area under receiver operating characteristic curve of 0.755, sensitivity of 73.5%, and specificity of 71.0%. Conclusions: The elevated hardness of PG identified high-risk PCA and served as an independent marker of high-risk PCA. As a non-invasive imaging modality, the RTE could be potentially used in routine clinical practice for the detection of high-risk PCA to decrease unnecessary biopsies and reduce overtreatment. [ABSTRACT FROM AUTHOR]

PURPOSE: Chronic recurrent parotitis (CRP) is a non-obstructive disease with episodes characterized by painful swelling of the parotid gland. It presents in both a juvenile and an adult form, with no clear information on its actual origin. Diagnosis is based on patient medical history and ultrasound examination but is frequently not correctly identified. Acoustic Radiation Force Impulse Imaging (ARFI) is a novel ultrasound elastography technology that has recently been implemented in the diagnostic work-up of patients with malignancies. This study aimed to answer whether ARFI can reasonably be employed in the initial examination and follow-up during therapy in patients with CRP. MATERIAL AND METHODS: Mechanical tissue properties of the salivary glands were analyzed by ARFI in 37 parotid glands of patients with CRP. RESULTS: Having integrated ARFI into our diagnostic protocol for CRP, affected parotid glands were found to exhibit lower tissue elasticity compared to both healthy contralateral glands in the same individuals as well as those of healthy individuals. Most importantly, this method enabled us to quantitatively assess the patient benefit of therapy regarding the recovery of the glands' diseased parenchyma. CONCLUSIONS: ARFI provides a quick, easy, and reliable diagnostic tool for the assessment of disease severity and progression in patients with CRP that can be seamlessly implemented into preexisting ultrasound protocols. [ABSTRACT FROM AUTHOR]

Purpose: This was a feasibility study of shear wave ultrasound elastography for characterization of liver tumors and to compare the tissue elasticity values of hepatocellular carcinoma (HCC), liver metastases, and normal liver tissues. Methods: Forty-one patients and 30 healthy volunteers were recruited and categorized into HCC, liver metastasis, and control groups based on their computed tomography and sonographic examinations. Elasticity values of different groups were compared statistically. Results: Mean (standard deviation) elasticity values for HCC, liver metastasis, and normal liver tissue were 51.45 (14.96), 49.89 (13.82), and 6.63 (1.65) kilopascal, respectively. Statistically significant differences were found between the elasticity values of HCC and liver metastasis with normal liver tissue. Based on the receiver operating characteristics analysis, 18.25 kilopascal may differentiate the malignant focal liver lesions from the normal liver tissue with both sensitivity and specificity of 100%. Conclusion: Shear wave ultrasound elastography may be able to differentiate HCC and liver metastasis from normal liver tissue based on the tissue elasticity values. [ABSTRACT FROM AUTHOR]

The material properties of the trabeculae (tissue-level properties), together with the trabecular architecture and the bone volume fraction determine the apparent millimetre-scale bone mechanical properties. We present a novel method to measure trabecular tissue elastic modulus E t using resonant ultrasound spectroscopy (RUS). The first mechanical resonance frequency f e of a freestanding cuboid specimen is measured and used to back-calculate E t . The steps of the back-calculation are (1) the apparent stiffness tensors C ( E t ˜ ) is computed using micro-finite elements for a set of trial values of tissue Young's modulus E t ˜ based on the computed tomography image of the specimen; (2) the modeled free-vibration resonance frequencies f m ( E t ˜ ) of the specimen is calculated with the Rayleigh-Ritz method using C ( E t ˜ ) ; (3) finally, E t is obtained by interpolation using f e and f m ( E t ˜ ) . Four bovine bone specimens were tested (nominal size 5×6 × 6 mm 3 ). Average (standard deviation) of E t was 13.12 (1.06) GPa. The measurement of a single resonance frequency enabled an estimation of tissue elasticity in line with available data. RUS is a non destructive technique relatively easy to implement compared to traditional mechanical testing. The novel method could contribute to a better documentation of bone tissue elasticity which is an important parameter of micro-finite element analyses for the clinical assessment of bone strength. [ABSTRACT FROM AUTHOR]

Background: Further progress in restoring a woman's health may be possible if a patient with a damaged pelvic floor could undergo medical imaging and biomechanical diagnostic tests. The results of such tests could contribute to the analysis of multiple treatment options and suggest the optimal one for that patient. Aim: To develop a new approach for the biomechanical characterization of vaginal conditions, muscles, and connective tissues in the female pelvic floor. Methods: Vaginal tactile imaging (VTI) allows biomechanical assessment of the soft tissue along the entire length of the anterior, posterior, and lateral vaginal walls at rest, with manually applied deflection pressures and with muscle contraction, muscle relaxation, and Valsalva maneuver. VTI allows a large body of measurements to evaluate individual variations in tissue elasticity, support defects, as well as pelvic muscle function. Presuming that 1) the female pelvic floor organs are suspended by ligaments against which muscles contract to open or close the outlets and 2) damaged ligaments weaken the support and may reduce the force of muscle contraction, we made an attempt to characterize multiple pelvic floor structures from VTI data. Results: All of the 138 women enrolled in the study were successfully examined with the VTI. The study subjects have had normal pelvic support or pelvic organ prolapse (stages I-IV). The average age of this group of subjects was 60±15 years. We transposed a set of 31 VTI parameters into a quantitative characterization of pelvic muscles and ligamentous structures. Interpretation of the acquired VTI data for normal pelvic floor support and prolapse conditions is proposed based on biomechanical assessment of the functional anatomy. Conclusion: Vaginal tactile imaging allows biomechanical characterization of female pelvic floor structures and tissues in vivo, which may help to optimize treatment of the diseased conditions such as prolapse, incontinence, atrophy, and some forms of pelvic pain. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Retracted blood clots have been previously recognized to be more resistant to drug-based thrombolysis methods, even with ultrasound and microbubble enhancements. Microtripsy, a new histotripsy approach, has been investigated as a non-invasive, drug-free and image-guided method that uses ultrasound to break up clots with improved treatment accuracy and a lower risk of vessel damage compared with the traditional histotripsy thrombolysis approach. Unlike drug-mediated thrombolysis, which is dependent on the permeation of the thrombolytic agents into the clot, microtripsy controls acoustic cavitation to fractionate clots. We hypothesize that microtripsy thrombolysis is effective on retracted clots and that the treatment efficacy can be enhanced using strategies incorporating electronic focal steering. To test our hypothesis, retracted clots were prepared in vitro and the mechanical properties were quantitatively characterized. Microtripsy thrombolysis was applied on the retracted clots in an in vitro flow model using three different strategies: single-focus, electronically-steered multi-focus and dual-pass multi-focus. Results show that microtripsy was used to successfully generate a flow channel through the retracted clot and the flow was restored. The multi-focus and the dual-pass treatments incorporating the electronic focal steering significantly increased the recanalized flow channel size compared to the single-focus treatments. The dual-pass treatments achieved a restored flow rate up to 324 mL/min without cavitation contacting the vessel wall. The clot debris particles generated from microtripsy thrombolysis remained within the safe range. The results of this study show the potential of microtripsy thrombolysis for retracted clot recanalization with the enhancement of electronic focal steering. [ABSTRACT FROM AUTHOR]

We report quantitative photoacoustic elastography (QPAE) capable of measuring Young's modulus of biological tissue in vivo in humans. By combining conventional PAE with a stress sensor having known stress- strain behavior, QPAE can simultaneously measure strain and stress, from which Young's modulus is calculated. We first demonstrate the feasibility of QPAE in agar phantoms with different concentrations. The measured Young's modulus values fit well with both the empirical expectation based on the agar concentrations and those measured in an independent standard compression test. Next, QPAE was applied to quantify the Young's modulus of skeletal muscle in vivo in humans, showing a linear relationship between muscle stiffness and loading. The results demonstrated the capability of QPAE to assess the absolute elasticity of biological tissue noninvasively in vivo in humans, indicating its potential for tissue biomechanics studies and clinical applications. [ABSTRACT FROM AUTHOR]

Copyright of Polish Journal of Sports Medicine / Medycyna Sportowa is the property of Agencja Wydawnicza Medsportpress Sp. z o. o. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We examined breast tissue elasticity during the menstrual cycle using real-time shear wave elastography (RT-SWE), a recent technique developed for soft tissue imaging. Written informed consent for RT-SWE was obtained from all eligible patients, who were healthy women aged between 19 and 52 y. Young's moduli of the breast tissue in the early follicular, late phase and luteal phase were compared. There were no significant differences in the mean, maximum and minimum elasticity values (Emean, Emax and Emin) and standard deviation (ESD). RT-SWE of glandular tissue revealed that ESD was increased in the early follicular phase compared with the luteal phase. Means ± SD of Emin, Emax and Emean in glandular tissue were 5.174 ± 2.138, 8.308 ± 3.166 and 6.593 ± 2.510, respectively, and in adipose tissue, 3.589 ± 2.083, 6.733 ± 3.522 and 4.857 ± 2.564, respectively. There were no significant differences in stiffness between glandular and adipose tissues throughout the menstrual cycle, but glandular tissue stiffness was lower in the luteal phase than in the early follicular phase. On the basis of these observations in normal healthy women, we believe we have obtained sufficient information to establish the baseline changes in human breast elasticity during the menstrual cycle. In the future, we intend to compare the elasticity values of healthy breast tissue with those of breast tissue affected by various pathologies. Our results reveal the significant potential of RT-SWE in the rapid and non-invasive clinical diagnosis of breast diseases, such as breast cancers. [ABSTRACT FROM AUTHOR]

X-ray mammography is commonly used to scan cancer or tumors in breast using low dose x-rays. But mammograms suffer from low contrast problem. The breast is compressed in mammography to reduce x-ray scattering effects. As tumors are stiffer than normal tissues, they undergo smaller deformation under compression. Therefore, image intensity at tumor region may change less than the background tissues. In this study, we try to find out compression induced contrast from multiple mammographic images of tumorous breast phantoms taken with different compressions. This is an extended work of our previous simulation study with experiment and more analysis. We have used FEM models for synthetic phantom and constructed a phantom using agar and n-propanol for simulation and experiment. The x-ray images of deformed phantoms have been obtained under three compression steps and a non-rigid registration technique has been applied to register these images. It is noticeably observed that the image intensity changes at tumor are less than those at surrounding which induce a detectable contrast. Addition of this compression induced contrast to the simulated and experimental images has improved their original contrast by a factor of about 1.4~2. We think the findings of this study will be helpful for clinical applications. [ABSTRACT FROM AUTHOR]

Recent studies have provided a theoretical framework for including entropic elasticity in the free energy landscape of proteins under mechanical force. Accounting for entropic elasticity using polymer physics models has helped explain the hopping behavior seen in single molecule experiments in the low force regime. Here, we expand on the construction of the free energy of a single protein domain under force proposed by Berkovich et al. to provide a free energy landscape for N tandem domains along a continuous polypeptide. Calculation of the free energy of individual domains followed by their concatenation provides a continuous free energy landscape whose curvature is dominated by the worm-like chain at forces below 20 pN. We have validated our free energy model using Brownian dynamics and reproduce key features of protein folding. This free energy model can predict the effects of changes in the elastic properties of a multidomain protein as a consequence of biological modifications such as phosphorylation or the formation of disulfide bonds. This work lays the foundations for the modeling of tissue elasticity, which is largely determined by the properties of tandem polyproteins. [ABSTRACT FROM AUTHOR]

Purpose: A scanning acoustic microscope (SAM) uses an ultrasound to image an object by plotting the speed-of-sound (SOS) through tissues on screen. Because hard tissues result in great SOS, SAM can provide data on the tissue elasticity. This paper investigated the utility of SAM in evaluating thyroid lesions. Methods: Formalin-fixed, paraffin sections were scanned with a 120 MHz transducer. SOS through each area was calculated and plotted on the screen to provide histological images, and SOS of each lesion was compared and statistically analyzed. Results: High-concentrated colloids, red blood cells, and collagen fibers showed great SOS, while low-concentrated colloids, parathyroids, lymph follicles, and epithelial tissues including carcinomas demonstrated lower SOS. SAM clearly discriminated structure of thyroid components corresponding to low magnification of light microscopy. Thyroid tumors were classified into three groups by average SOS: the fast group consisted of follicular adenomas/carcinomas and malignant lymphomas; the slow group contained poorly differentiated/undifferentiated carcinomas; and the intermediate group comprised papillary/medullary carcinomas. Fragmented colloids, irregular-shaped follicles, and desmoplastic reactions were observed in the invasive area of surrounding carcinomas. Conclusion: The SAM imaging method had the following benefits: 1) precise images were acquired in a few minutes without special staining; 2) structural irregularity and desmoplastic reactions, which indicated malignancy, were detected; 3) images reflected tissue elasticity, which was statistically comparable among lesions by SOS; 4) follicular functional activity was predictable by converting colloid concentration to SOS; and 5) tumor classification was predictable by SOS because more poorly differentiated carcinomas had a tendency to show lower SOS. [ABSTRACT FROM AUTHOR]

In tissue elasticity imaging, measuring the strain tensor components is necessary to solve the inverse problem. However, it is impractical to measure all the tensor components in ultrasound or MRI elastography because of their anisotropic spatial resolution. The objective of this study is to compute 3D strain tensor maps from the 3D CT images of a tissue-mimicking phantom. We took 3D micro-CT images of the phantom twice with applying two different mechanical compressions to it. Applying the 3D image correlation technique to the CT images under different compression, we computed 3D displacement vectors and strain tensors at every pixel. To evaluate the accuracy of the strain tensor maps, we made a 3D FEM model of the phantom, and we computed strain tensor maps through FEM simulation. Experimentally obtained strain tensor maps showed similar patterns to the FEM-simulated ones in visual inspection. The correlation between the strain tensor maps obtained from the experiment and the FEM simulation ranges from 0.03 to 0.93. Even though the strain tensor maps suffer from high level noise, we expect the x-ray strain tensor imaging may find some biomedical applications such as malignant tissue characterization and stress analysis inside the tissues. [ABSTRACT FROM AUTHOR]

Abstract: Sono-myography and sono-myoelastography have been found useful in the investigation of myofascial trigger points. The objective of this study was to use the same techniques to investigate the morphology, stiffness and blood flow of tender points in women with fibromyalgia and to compare the results with those for samples from healthy patients. Algometry tests indicated significant differences between groups (p < 0.001). Elliptical and hypoechoic areas were observed in the ultrasound images of the upper trapezius in both groups. No differences between groups were found in the number of hypoechoic areas (p = 0.167, t = 1.008); blood flow also did not differ between the groups. Larger hypoechoic areas were found in the fibromyalgia group (p = 0.139, t = 1.317). Sono-myoelastography did not reveal greater stiffness in these areas compared with the rest of the muscle. These results lead us to believe that sono-myoelastography and sono-myography, used in the diagnosis of myofascial trigger points, may not be able to discriminate tender points. [Copyright &y& Elsevier]

Ten years have passed since the first commercial equipment for elastography was released; since then clinical utility has been demonstrated. Nowadays, most manufacturers offer an elastography option. The most widely available commercial elastography methods are based on strain imaging, which uses external tissue compression and generates images of the resulting tissue strain. However, imaging methods differ slightly among manufacturers, which results in different image characteristics, for example, spatial and temporal resolution, and different recommended measurement conditions. In addition, many manufacturers have recently provided a shear wave-based method, providing stiffness images based on shear wave propagation speed. Each method of elastography is designed on the basis of assumptions of measurement conditions and tissue properties. Thus, we need to know the basic principles of elastography methods and the physics of tissue elastic properties to enable appropriate use of each piece of equipment and to obtain more precise diagnostic information from elastography. From this perspective, the basic section of this guideline aims to support practice of ultrasound elastography. [ABSTRACT FROM AUTHOR]

Abstract: The extremely fine structure of vertebral cortex challenges reliable determination of the tissue''s anisotropic elasticity, which is important for the spine''s load carrying patterns often causing pain in patients. As a potential remedy, we here propose a combined experimental (ultrasonic) and modeling (micromechanics) approach. Longitudinal acoustic waves are sent in longitudinal (superior-inferior, axial) as well as transverse (circumferential) direction through millimeter-sized samples containing this vertebral cortex, and corresponding wave velocities agree very well with recently identified ‘universal’ compositional and acoustic characteristics (J Theor Biol 287:115, 2011), which are valid for a large data base comprising different bones from different species and different organs. This provides evidence that the ‘universal’ organization patterns inherent to all the bone tissues of the aforementioned data base also hold for vertebral bone. Consequently, an experimentally validated model covering the mechanical effects of this organization patterns (J Theor Biol 244:597, 2007, J Theor Biol 260:230, 2009) gives access to the complete elasticity tensor of human lumbar vertebral bone tissue, as a valuable input for structural analyses aiming at patient-specific fracture risk assessment, e.g. based on the Finite Element Method. [Copyright &y& Elsevier]

Abstract: Collagen, an ubiquitous biomaterial, confers robustness and resilience to connective tissues. In this study, we analyzed the structure and elasticity profile of collagen from the vaginal wall connective tissue of healthy pre-menopausal (pre-M) and postmenopausal (post-M) women. The histological staining assisted study with an atomic force microscope renders the examination of native collagen fibers on site of the connective tissue from nanoscopic scale to microscopic scale with high spatial resolution. Our results suggest that during menopause, collagen’s structure and elasticity are subject to changes at all levels of organization- between individual collagen fibers, between collagen and muscle, and between collagen and other matrix elements. The systematic analysis of the native structure and mechanical properties of collagen within a tissue provides a potential way to study non-fatal conditions such as pelvic organ prolapse and other genito-urinary disorders, where the initial symptoms are subtle and multivariate, and where early detection of patient’s condition may allow better non-invasive interventions and reduce the number of women undergoing surgical correction of these common disorders. [Copyright &y& Elsevier]

The article discusses the application of real-time sonoelastography (RTS) in a clinical setting for a few musculoskeletal disease. It explores the principles and developments of RTS which is an ultrasound-based technique that provides information on tissue elasticity and shows promising results and potentialities in normal and pathologic tissues in muscle and tendon disorder applications. It also cites the use of RTS as a research tool to derive novel diagnostic information for biomechanics.

Abstract: When ultrasound imaging is used for breast cancer diagnosis, the lesion''s morphology is usually used to determine if the lesion is benign or malignant. Sometimes, the information provided by the procedure may not be adequate to make an accurate judgment. Additional information is needed, such as the stiffness of the lesion relative to its surrounding tissue. This paper presents an ultrasound accessory device designed to achieve this purpose. The device is easy to operate and is similar in use to a normal clinical breast ultrasound examination. A sonologist must only attach an ultrasound probe to the device and then slide it across the lesion maintaining a constant compression depth. The built-in inverse biomechanical model of the device will then calculate the predicted stiffness ratio of the lesion relative to its surrounding tissue based on the measured palpation data. Modelling and experiments have been performed on phantoms with embedded inclusions. The experimental results show that the stiffness ratio of the inclusion to its surrounding material can be accurately predicted by the handheld device. A preliminary clinical test was also performed to demonstrate the use of this device in vivo, to offer additional information to aid classification of the tumor as benign or malignant when complemented with ultrasound images. [Copyright &y& Elsevier]

Abstract: Results from the application of a novel nonlinear hybrid reconstruction algorithm within a Digital Image Elasto-Tomography (DIET) system are presented. A hybrid reconstruction algorithm was optimized to solve for the elasticity distribution of two heterogeneous silicone phantoms using a shape-based parameterization. The hybrid algorithm achieved comparable performance to Combinatorial Optimization methods with significantly less computational expense. The specificity of three-parameter reconstruction was confirmed by successful reconstruction of a homogeneous silicone phantom, indicating the potential suitability of the DIET system for application to inclusion imaging in elastography. [Copyright &y& Elsevier]

Abstract: Strain distribution in compressed tissues gives information about elasticity of the tissues. We have measured strain from two sets of 3D micro-CT images of a breast-mimicking phantom; one obtained without compressing the phantom and the other with compressing it. To measure strain, we first calculated compression-induced displacements of high-intensity feature patterns in the image. In measuring displacement of a pixel of interest, we searched the pixel in the compressed-phantom image, whose surrounding resembles the uncompressed-phantom image most closely, using the image correlation technique. From the displacement data, we calculated average strain at a region of interest. With the calculated average strains, we could distinguish the hard inclusion in the phantom which was not distinguishable from the background body of the phantom in the ordinary micro-CT images. The calculated strains account for stiffness of the tissue of interest, one of the important parameters for diagnosing malignant tissues. We present experimental results of the displacement and strain measurement along with FEM analysis results. [Copyright &y& Elsevier]