Ultrasound Shear Wave Elastography Research Articles

Ultrasound shear wave elastography in pediatric stricturing small bowel Crohn disease: correlation with histology and second harmonic imaging microscopy.

Preclinical animal as well as small exploratory ex vivo and in vivo human studies have suggested that bowel wall shear wave speed (SWS) measurements may be a noninvasive biomarker of intestinal damage. To evaluate the relationships between bowel wall stiffness, measured using ultrasound shear wave elastography (SWE), and intestinal fibrosis and smooth muscle hypertrophy as determined by (1) histology and (2) second harmonic imaging microscopy (SHIM) in surgically resected ileal strictures from pediatric Crohn disease patients. Nineteen pediatric Crohn disease patients with symptomatic ileal strictures underwent research ultrasound examinations before surgical resection between December 2017 and September 2020. Two-dimensional SWE was performed through the area of the most severe stenosis, with measurements obtained from the bowel wall at the 9:00, 12:00 and 3:00 o'clock locations with 0%, 10% and 20% abdominal strain. Overall right lower quadrant stiffness also was documented. Median bowel wall and overall right lower quadrant SWS measurements were correlated with bowel wall histological scores of inflammation, fibrosis and smooth muscle proliferation as well as SHIM collagen signal. Diagnostic ultrasound SWE imaging was obtained from 18 participants. The median age was 16.8 years. There were negative correlations between histological mucosal active inflammation and both bowel wall SWS with 10% abdominal strain (r=-0.50, P = 0.04) and overall right lower quadrant SWS with 20% abdominal strain (r=-0.69, P = 0.002). There were positive correlations between histological muscularis propria inner layer smooth muscle hypertrophy and both median bowel wall SWS with 10% abdominal strain (r = 0.72, P = 0.002) and overall right lower quadrant SWS with 20% abdominal strain (r = 0.71, P = 0.002). There were no associations between ultrasound stiffness metrics and bowel wall SHIM collagen measurements. Bowel wall and overall right lower quadrant ultrasound stiffness measurements correlate with mucosal active inflammation and muscularis propria smooth muscle hypertrophy in pediatric stricturing ileal Crohn disease, but not with intestinal fibrosis.

The influence of idiopathic chronic neck pain on upper trapezius and sternocleidomastoid muscle activity and elasticity during functional reaching: A cross-sectional study

It remains unclear whether idiopathic chronic neck pain is associated with changes in muscle stiffness alongside alterations in neuromuscular control. Therefore, the purpose of this study was to determine the influence of idiopathic chronic neck pain on the muscle stiffness and muscle activity of the upper trapezius and sternocleidomastoid muscles during the maintenance of unilateral and bilateral functional reaching tasks. Surface electromyography (EMG) and ultrasound shear wave elastography were collected from the sternocleidomastoid and upper trapezius muscles in 18 individuals with idiopathic chronic neck pain and 18 matched healthy controls. Participants completed three functional reaching tasks; 1) unilateral forward reach, 2) bilateral forward reach, and 3) unilateral upward reach, and held at the top of each reaching movement for data to be collected bilaterally. A univariate ANOVA was utilized for each outcome measure (mean EMG amplitude and shear wave velocity) and each reaching task. Individuals with idiopathic chronic neck pain exhibited significantly lower upper trapezius activation during bilateral reaches without corresponding changes to stiffness during similar trials. Similarly, this cohort exhibited decreased sternocleidomastoid stiffness during forward reaching, without corresponding activation changes. Lastly, women demonstrated consistently higher sternocleidomastoid activation and stiffness when compared to men. These findings indicate individuals with idiopathic chronic neck pain may adapt their movement strategies, possibly for pain avoidance. The demonstrated changes in muscle stiffness independent of changes in muscle activity highlight the importance of evaluating both muscle stiffness and activation in individuals with idiopathic chronic neck pain prior to designing rehabilitation programs.

Lack of Objective Measurement in the Initial Screening and Follow-Up of Patients Who Report Whiplash Injury—Is Elastography of the Trapezius Muscle an Answer?

Background: Painfully decreased cervical range of motion accompanied by muscle spasm is a common presentation of whiplash injury of the neck. Stiffness of the cervical muscles can be assessed by ultrasound shear wave elastography (SWE), expressed in kilopascals (kPa). The hypothesis: SWE of the trapezius muscle is an objective measurement suitable for the initial screening and follow-up of patients who report whiplash injury. Methods and results: A total of 99 patients after whiplash injury were compared to 75 control participants. Mean trapezius stiffness was 82.24 ± 21.11 vs. 57.47 ± 13.82 for whiplash patients and controls, respectively. The cut-off value of SWE of 75.8 kPa showed 77% accuracy in correctly assigning patients to the whiplash or control group. To evaluate whether SWE can be used as a follow-up method of recovery after a whiplash injury, initial and endpoint SWE (after six months, n = 24) was carried out. Patients reporting no recovery showed similar SWE values as completely recovered patients. This finding refutes the second part of our hypothesis. Conclusions: SWE is a method that can be used for the initial screening of patients with whiplash injury, but we are still searching for an objective measurement that can be used in the follow-up of recovery.

Posterior shoulder capsule of the dominant arm is stiffer in baseball players than that in nonthrowing population.

Posterior shoulder capsule tightness is one of the factors for shoulder injuries in overhead athletes. Recent studies have shown the posterior capsule of the dominant arm to be stiffer than that of the nondominant arm in baseball players. However, whether posterior capsule tightness in the dominant arm is exclusive to overhead athletes remains unknown. This study aimed to investigate whether the posterior shoulder capsule of the dominant arm in baseball players is stiffer than that in nonthrowing population. Fifteen male collegiate asymptomatic baseball players (baseball-player group) and fifteen male college students who did not partake in overhead sports (nonthrowing group) participated in this study. We measured the shear moduli of the middle and inferior posterior capsules, superior infraspinatus, inferior infraspinatus, teres minor, and posterior deltoid in the dominant arm by ultrasound shear wave elastography. We compared shear moduli between the two groups using an independent samples t-test and Mann-Whitney test. In addition, we investigated the correlation between the range of glenohumeral internal rotation and each shear modulus in each group using the Pearson correlation coefficient. The shear moduli in the baseball-player group were significantly higher than those in the nonthrowing group in both the middle posterior capsule (baseball-player group: 36.1±5.6kPa vs. nonthrowing group: 29.0±8.6kPa; P=.018) and inferior posterior capsule (37.1±9.6kPa vs. 27.9±6.8kPa; P=.002). However, no difference in the shear moduli of individual muscle groups was identified. The glenohumeral internal rotation range exhibited a statistically significant negative correlation with the shear modulus of the inferior posterior capsule in the baseball-player group (Pearson correlation coefficient=-0.586, P=.022). Our findings suggest that the posterior shoulder capsule of the dominant arm in baseball players is stiffer than that in nonthrowing population.

Influence of the Field of View on Shear Wave Velocity Estimation

Abstract Tissue elasticity contains important information for physicians in diagnosis and treatment, and, e.g., can help in tumor detection because tumors are stiffer than healthy tissue. Ultrasound shear wave elastography imaging (US-SWEI) can be used to estimate tissue stiffness by measuring the velocity of induced shear waves. Commonly, a linear US probe is used to track shear waves at a high imaging frequency in 2D. Realtime US-SWEI is limited by the required time for data processing. Hence, reducing the imaging field of view (FOV) is beneficial as it decreases the size of the acquired data and thereby the acquisition, transfer and processing time. However, a decrease in the FOV has the disadvantage that shear waves are tracked over a smaller distance and thus, also fewer sampling points are available for velocity estimation. This trade-off between a smaller FOV and thus, a smaller data size, and the accuracy of shear wave velocity estimation is investigated in this work. For this purpose, shear waves were tracked with a linear US probe in gelatin phantoms with four different stiffness values. During data processing, we reduced the FOV virtually from 38.1mm to 2.1mm. It was found that a reduction of the FOV to 4.5mm leads to an overestimation of up to five times larger shear wave velocities but still allows to distinguish between phantoms of different stiffness. However, not all estimated velocity values could be clearly assigned to the correct stiffness value. The smallest studied FOV of 2.1mm was not sufficient for distinguishing between the phantoms anymore.

Preoperative Liver Stiffness is Associated With Hospital Length of Stay After Cardiac Surgery

Risk assessment models for cardiac surgery do not account for the degrees of liver dysfunction. Ultrasound shear-wave elastography measures liver stiffness (LSM), a quantitative measurement related to fibrosis, congestion, and inflammation. The authors hypothesized that preoperative liver stiffness would be associated with hospital length of stay after cardiac surgery. Prospective observational study. University hospital, single center. One hundred five adult patients undergoing nonemergent cardiac surgery. Preoperative liver stiffness measured by ultrasound elastography. The associations were analyzed using linear mixed models, with adjustments for preoperative variables, duration of cardiopulmonary bypass, and type of surgery. Median liver stiffness was 6.4 kPa (range, 4.1-18.6 kPa). The median length of hospital stay was 6 days (range, 3-18 d). Each unit increase in liver stiffness, treated as a continuous variable, was associated with an increase of 0.32 ± 0.10 days in the hospital (p=0.002). When treated as a categorical variable (<6 kPa, 6-9.4 kPa, and ≥9.5 kPa), LSM ≥9.5 kPa v LSM <6 kPa was associated strongly with an increase in hospital length of stay of 3.25 ± 0.87 days (p=0.0003). A preoperative LSM ≥9.5 kPa was associated with a significantly longer postoperative hospital length of stay. This association appeared independent of preoperative comorbidities commonly associated with coronary disease. Preoperative liver stiffness is a novel risk metric that is associated with the postoperative hospital length of stay after cardiac surgery.

Value of shear wave elasticity in predicting the efficacy of neoadjuvant chemotherapy in different molecular types

PurposeThe purpose of this study was to evaluate the response to neoadjuvant chemotherapy (NAC) of different molecular subtypes of breast cancer using shear wave ultrasound elastography (SWE). MethodsNinety-eight patients with final diagnoses of breast cancer prior to NAC were examined with SWE and B-mode ultrasound. These parameters were compared with the response evaluation criteria in solid tumors (RECIST) index and pathological diagnoses. Then, we recorded the area under the receiver operating characteristic (ROC) curve. Immunohistochemical markers, including estrogen receptor (ER), progesterone receptor (PR), Ki67 index, and human epidermal growth factor receptor 2 (HER2) score, were examined before neoadjuvant treatment. Then, the diagnostic efficacy of SWE in different molecular subtypes was evaluated. ResultsOne-way analysis of variance revealed that age, tumor margin, the change in tumor size after chemotherapy, and the average (Emean), minimum (Emin), and maximum (Emax) values from shear wave elastography ultrasound before chemotherapy were related to the RECIST index. Multivariate regression revealed that age, tumor margin, the change in tumor size after chemotherapy, and Emax were independently correlated with the RECIST index. According to the ROC curve, the area under the curve (AUC) of Emax was 0.773. The AUC of Emean, Emin, and the ratio between tumor tissue and normal tissue (EI) were 0.630, 0.617, and 0.510, respectively. The Emax, Emin, Emean, and EI before and after NAC were significantly different (p ≤ 0.05). There was statistical significance in Luminal B type and HER2 enriched type in correlation results of the Emax values and RECIST indexes of different molecular subtypes. However, there was no significant difference in the Luminal A type and Triple negative types. There was no significant difference in the Emax values before NAC between the pathologic complete response (pCR) group and the non-pCR group (p > 0.05). ConclusionEmax can be used to predict the response to NAC in women with invasive breast cancer, especially those with the Luminal B type and HER2 enriched type, but it cannot be used to predict pCR to NAC.

Shear wave elastography of liver

Synopsis: The use of ultrasound shear wave elastography for non-invasive assessment of liver fibrosis has grown rapidly. This presentation discusses the best practices for ultrasound shear wave elastography in determining liver stiffness. There will also be sharing of the application and limitations of this technique.

Effect of Depth on Ultrasound Point Shear Wave Elastography in an Elasticity Phantom

Background: Phantom studies are widely used to assess variability in measurements. This study aimed to assess the reliability and accuracy of point Shear Wave elastography (pSWE) measurements of an elasticity phantom. Methods: Measurements were obtained by an experienced certified clinical sonographer at three different depth levels in kPa, using a curvilinear 5-1MHz transducer of the EPIQ7 ultrasound imaging system. Results: A total of 180 pSWE measurements were obtained at three different depth levels (three cm, five cm, and seven cm) of the phantom background. The mean CV of pSWE was low at all depths (3 cm: 8.8%; 5 cm: 7%; 7 cm: 7.2%). There was a significant difference between measurements at depths of 3 cm vs. 7 cm (MD: −0.85, 95% CI −1.5, −0.11, p = 0.024) and measurements at depths 5 cm vs. 7 cm (MD: −1.1, 95% CI −1.7, −0.47, p = 0.001). An overestimation of mean pSWE measurements at a depth of 7 cm was noted compared to the manufacturer’s value (2.7%, p = 0.006). Conclusions: Superficial phantom SWE measurements in this study had low variability compared to deep measurement. pSWE measurements at deep levels can be overestimated.

Metformin reduces myogenic contracture and myofibrosis induced by rat knee joint immobilization via AMPK-mediated inhibition of TGF-β1/Smad signaling pathway

ABSTRACT Purpose The two structural components contributing to joint contracture formation are myogenic and arthrogenic contracture, and myofibrosis is an important part of myogenic contracture. Myofibrosis is a response to long-time immobilization and is described as a condition with excessive deposition of endomysial and perimysial connective tissue components in skeletal muscle. The purpose of this study was to confirm whether metformin can attenuate the formation of myogenic contracture and myofibrosis through the phosphorylation level of adenosine monophosphate-activated protein kinase (AMPK) and inhabitation of subsequent transforming growth factor beta (TGF-β) 1/Smad signaling pathway. Materials and Methods An immobilized rat model was used to determine whether metformin could inhibit myogenic contracture and myofibrosis. The contents of myogenic contracture of knee joint was calculated by measuring instrument of range of motion (ROM), and myofibrosis of rectus femoris were determined by ultrasound shear wave elastography and Masson staining. Protein expression of AMPK and subsequent TGF-β1/Smad signaling pathway were determined by western blot. Subsequently, Compound C, a specific AMPK inhibitor, was used to further clarify the role of the AMPK-mediated inhibition of TGF-β1/Smad signaling pathway. Results We revealed that the levels of myogenic contracture and myofibrosis were gradually increased during immobilization, and overexpression of TGF-β1-induced formation of myofibrosis by activating Smad2/3 phosphorylation. Activation of AMPK by metformin suppressed overexpression of TGF-β1 and TGF-β1-induced Smad2/3 phosphorylation, further reducing myogenic contracture and myofibrosis during immobilization. In contrast, inhibition of AMPK by Compound C partially counteracted the inhibitory effect of TGF-β1/Smad signaling pathway by metformin. Conclusion Notably, we first illustrated the therapeutic effect of metformin through AMPK-mediated inhibition of TGF-β1/Smad signaling pathway in myofibrosis, which may provide a new therapeutic strategy for myogenic contracture.

Shear Wave Elastography Implementation on a Portable Research Ultrasound System: Initial Results

Ultrasound shear wave elastography (SWE) has emerged as a promising technique that enables the quantitative estimation of soft tissue stiffness. However, its practical implementation is complicated and presents a number of engineering challenges, including high-energy burst transmission, high-frame rate data acquisition and high computational requirements to process huge datasets. Therefore, to date, SWE has only been available for high-end commercial systems or bulk and expensive research platforms. In this work, we present a low-cost, portable and fully configurable 256-channel research system that is able to implement various SWE techniques. We evaluated its transmit capabilities using various push beam patterns and developed algorithms for the reconstruction of tissue stiffness maps. Three different push beam generation methods were evaluated in both homogeneous and heterogeneous experiments using an industry-standard elastography phantom. The results showed that it is possible to implement the SWE modality using a portable and cost-optimized system without significant image quality losses.

Abstract 6381: Superior effects of polymeric micelles in reprogramming tumor microenvironment and enhancing nano-immunotherapy

Abstract Nano-immunotherapy has high potential to improve cancer patient outcomes, as already demonstrated in triple negative breast cancer with the combination of nanoparticle albumin-bound paclitaxel and the immune checkpoint blocker antibody, atezolizumab. This regimen, however, does not lead to complete cure with median survival lasting less than two years. To increase patient survival, research focuses on repurposing common drugs to modulate the tumor microenvironment (TME), aiming to increase delivery of nanoparticles, antibodies and other drug regimens and improve immunostimulation. These drugs, however, exhibit certain dose-limitations and are associated with adverse effects. Here, taking advantage of the TME reprogramming capabilities of the approved antihistamine drug tranilast, we developed polymeric tranilast-loaded nanoparticles and explored their potential to modulate the TME more efficiently than the free drug. The results were striking as the micellar formulation of tranilast administered in a dose 100 times lower than that of the free drug reported superior reprogramming effects in two syngeneic triple negative breast tumor models. These effects were due to the enhanced intratumoral accumulation and cancer-associated fibroblast uptake of the nanoparticles compared to the free drug. Tranilast micelles were also found to promote significantly the delivery and efficacy of epirubicin micelles, overcome immune checkpoint resistance and induce tumor immunogenicity. Overall, the proposed micelles improved the efficacy of nano-immunotherapy in both breast cancer tumor models leading to complete cure. Furthermore, we employed the non-invasive and clinically applied ultrasound shear wave elastography method to monitor changes in tumor stiffness, which is the first effect caused by the tranilast micelles, and thus to determine an optimal dose-scheduling. Importantly, we found that tumor stiffness before the initiation of nano-immunotherapy was able to predict the efficacy of the treatment providing strong evidence for the potential of shear wave elastography to be used as a biomarker predictive of response. Our findings are very encouraging indicating that a) encapsulation of TME modulating drugs improves their pharmacokinetic properties, while allows for drastic reduction in the dose of administration, b) modulation of the TME can lead to complete cures of nano-immunotherapy in resistant to this therapy breast cancer tumor models, and c) ultrasound shear wave elastography can be employed for optimizing the use of TME modulating agents and for the prediction of tumor response to nano-immunotherapy allowing for optimized treatment protocols. Citation Format: Myrofora Panagi, Fotios Mpekris, Pengwen Chen, Chrysovalantis Voutouri, Yasuhiro Nakagawa, John D. Martin, Tetsuro Hiroi, Hiroko Hashimoto, Genichiro Ishii, Motohiro Kojima, Kazunori Kataoka, Horacio Cabral, Triantafyllos Stylianopoulos. Superior effects of polymeric micelles in reprogramming tumor microenvironment and enhancing nano-immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6381.

Abstract 6382: Targeting mast cells restores T cell infiltration and sensitizes sarcomas to PD-L1 inhibition

Abstract Despite recent advances in cancer research, developments in sarcoma treatment have been slow. The efficacy of chemotherapy in sarcoma is limited by the pathophysiology of surrounding tumor stroma. Abnormalities in the tumor microenvironment (TME) result in stiffening of the tumor and accumulation of mechanical stresses which in turn cause the extreme deformation and collapse of intratumoral vessels. Strategies to induce TME reprogramming with the aim to restore mechanical properties of the tissue as well as tumor blood vessel functionality involve the use of “mechanotherapeutics”. Herein, we exploited the potential of the antihistamine drug and mast cell stabilizer, ketotifen, to induce mechanotherapeutic effects in murine models of soft tissue and bone sarcoma. Mast cells are the first population of immune cells drawn to the tumorigenic nidus where they interact with multiple components of the TME. Yet, their role in tumor stroma remains enigmatic as they either promote or inhibit tumor development depending on the conditions. In agreement with other mechanotherapeutics, we found that ketotifen induces vascular normalization in a dose dependent manner as indicated by the increase in perfusion, higher open lumen fraction and pericyte coverage of the vessels. Moreover, in vivo ultrasound shear wave elastography confirmed the mechanotherapeutic properties of ketotifen in reducing tissue stiffness, while further ex vivo validation indicated that TME reprogramming is mediated by a significant reduction in cancer associated fibroblast and inhibition of collagen synthesis as well as of that of other extracellular matrix components. Furthermore, we found that ketotifen modulates the immune microenvironment to promote immunostimulation. Immune stimulation was mediated by both intratumoral T cell accumulation and higher cytotoxic to regulatory T cell ratio concomitantly with a pronounced reduction in tissue hypoxia and upregulation of leukocyte adhesion molecules on endothelium. As a result of ketotifen-induced TME reprogramming, the addition of ketotifen to doxorubicin-aPDL1 combination treatment exhibited therapeutic superiority as opposed to doxorubicin-aPDL1, offering a durable tumor remission and immunological memory following tumor rechallenge experiments. Taken together, our findings demonstrate that ketotifen has a dual role in shaping the TME: i) reducing intratumoral physical forces to improve perfusion and ii) establishing favorable immunogenic conditions. Therefore, incorporating such agents in clinical practice holds great promise in the treatment of refractory, advanced sarcomas. Citation Format: Myrofora Panagi, Fotios Mpekris, Chrysovalantis Voutouri, Christina Michael, Anastasia Constantinidou, John D. Martin, Triantafyllos Stylianopoulos. Targeting mast cells restores T cell infiltration and sensitizes sarcomas to PD-L1 inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6382.

Altered regional 3D shear wave velocity patterns in youth competitive alpine skiers suffering from patellar tendon complaints – a prospective case–control study

ABSTRACT Patellar tendon (PT) complaints are frequent throughout the population, with increased occurrence in athletes and, particularly, in youth competitive alpine skiers. Timely detection and treatment might improve prospects of recovery. Diagnostic modalities in clinical use to date rely on pain symptoms, manual palpation, and potentially, magnetic resonance imaging (MRI); however, MRI-based imaging yields limited sensitivity. Quantitatively measuring the morphological and mechanical properties of PTs by means of B-mode ultrasound and shear wave elastography (SWE), instead, may allow improved diagnosis or even early detection. We performed B-mode scans and three-dimensional ultrasound shear wave velocity (SWV) mapping and MRI of the PT in 106 youth skiers. A prospective one-year survey on health problems combined with clinical assessments served to categorize symptomatic and asymptomatic youth skiers. Skiers suffering from distal or proximal tendon complaints showed lower SWV in the respective tendon region than asymptomatic skiers (p = 0.035 and p = 0.019, respectively). Youth skiers with distal tendon complaints additionally exhibited decreased SWV in the proximal region compared to asymptomatic counterparts (p = 0.020). Cross-validated analysis of retrospective prediction indicated sensitivity and specificity in detecting tendon complaints in the range of 0.606–0.621 and 0.536–0.650, respectively. MRI detected distal tendon complaints with a sensitivity of 0.410 (12/29) but failed to detect any proximal cases. This study agrees with the most recent literature in that SWE holds promise as a valuable adjunct modality for the diagnosis of PT complaints or even the detection of subclinical prestages. However, to evaluate its prospective predictive value, long-term studies are warranted. Highlights Patellar tendon complaints are a frequent complaint in athletes, particularly in youth competitive alpine skiers, but timely quantitative detection of related tendon properties remains challenging. Quantitative B-mode US and three-dimensional ultrasound shear wave elastography assessments and magnetic resonance imaging were performed in youth competitive alpine skiers. Three-dimensional shear wave elastography was able to discern symptomatic from asymptomatic patellar tendons both in the distal and proximal tendon regions, whereas magnetic resonance imaging failed to detect any proximal cases.

Peripheral nerve defects repaired with autogenous vein grafts filled with platelet-rich plasma and active nerve microtissues and evaluated by novel multimodal ultrasound techniques

BackgroundDeveloping biocompatible nerve conduits that accelerate peripheral nerve regeneration, lengthening and functional recovery remains a challenge. The combined application of nerve microtissues and platelet-rich plasma (PRP) provides abundant Schwann cells (SCs) and various natural growth factors and can compensate for the deficiency of SCs in the nerve bridge, as well as the limitations of applying a single type of growth factor. Multimodal ultrasound evaluation can provide additional information on the stiffness and microvascular flow perfusion of the tissue. This study was designed to investigate the effectiveness of a novel tissue-engineered nerve graft composed of an autogenous vein, nerve microtissues and PRP in reconstructing a 12-mm tibial nerve defect and to explore the value of multimodal ultrasound techniques in evaluating the prognosis of nerve repair.MethodsIn vitro, nerve microtissue activity was first investigated, and the effects on SC proliferation, migration, factor secretion, and axonal regeneration of dorsal root ganglia (DRG) were evaluated by coculture with nerve microtissues and PRP. In vivo, seventy-five rabbits were equally and randomly divided into Hollow, PRP, Micro-T (Microtissues), Micro-T + PRP and Autograft groups. By analysing the neurological function, electrophysiological recovery, and the comparative results of multimodal ultrasound and histological evaluation, we investigated the effect of these new nerve grafts in repairing tibial nerve defects.ResultsOur results showed that the combined application of nerve microtissues and PRP could significantly promote the proliferation, secretion and migration of SCs and the regeneration of axons in the early stage. The Micro-T + PRP group and Autograft groups exhibited the best nerve repair 12 weeks postoperatively. In addition, the changes in target tissue stiffness and microvascular perfusion on multimodal ultrasound (shear wave elastography; contrast-enhanced ultrasonography; Angio PlaneWave UltrasenSitive, AngioPLUS) were significantly correlated with the histological results, such as collagen area percentage and VEGF expression, respectively.ConclusionOur novel tissue-engineered nerve graft shows excellent efficacy in repairing 12-mm defects of the tibial nerve in rabbits. Moreover, multimodal ultrasound may provide a clinical reference for prognosis by quantitatively evaluating the stiffness and microvescular flow of nerve grafts and targeted muscles.

The Revisited Frequency-Shift Method for Shear Wave Attenuation Computation and Imaging.

Ultrasound (US) shear wave (SW) elastography has been widely studied and implemented on clinical systems to assess the elasticity of living organs. Imaging of SW attenuation reflecting viscous properties of tissues has received less attention. A revisited frequency shift (R-FS) method is proposed to improve the robustness of SW attenuation imaging. Performances are compared with the FS method that we originally proposed and with the two-point frequency shift (2P-FS) and attenuation measuring US SW elastography (AMUSE) methods. In the proposed R-FS method, the shape parameter of the gamma distribution fitting SW spectra is assumed to vary with distance, in contrast to FS. Second, an adaptive random sample consensus (A-RANSAC) line fitting method is used to prevent outlier attenuation values in the presence of noise. Validation was made on ten simulated phantoms with two viscosities (0.5 and 2 Pa [Formula: see text]) and different noise levels (15 to -5 dB), two experimental homogeneous gel phantoms, and six in vivo liver acquisitions on awake ducks (including three normal and three fatty duck livers). According to the conducted experiments, R-FS revealed mean reductions in coefficients of variation (CV) of 62.6% on simulations, 62.5% with phantoms, and 62.3% in vivo compared with FS. Corresponding reductions compared with 2P-FS were 45.4%, 77.1%, and 62.0%, respectively. Reductions in normalized root-mean-square errors for simulations were 63.9% and 48.7% with respect to FS and 2P-FS, respectively.

Assessment of ultrasound shear wave elastography within muscles using different region of interest sizes, manufacturers, probes and acquisition angles: an ex vivo study.

The application of shear wave elastography (SWE) in assessment of the musculoskeletal system is affected by various factors. This study aimed to explore the influence of machines, probes, region of interest (ROI) sizes, and the acquisition angles on muscle shear wave speed (SWS). The SWS of ex vivo isolated muscles were acquired using 3 different machines (Aixplorer system, SuperSonic Imagine; Acuson S3000, Siemens Healthcare; Resona 7, Mindray) and 2 linear probes (Aixplorer system, SL 10-2 and SL 15-4). Also, 4 different ROI sizes (diameter 1-10 mm) and 9 different acquisition angles (0-40°) were tested. The SWS acquired under different conditions were compared, and the intra-class correlation coefficients (ICC) were used to evaluate reproducibility. There was a significant difference in SWS acquired using the 3 different machines (P<0.001) or with 9 different angles (P=0.008). There was no significant difference in SWS acquired using 2 probes (P=0.053) or 4 different ROI sizes (P=0.874, 0.778, and 0.865 for 3 operators, respectively). All machines produced substantial intra-system reproducibility (ICC, 0.61-0.80). Both probes demonstrated an almost perfect degree of intra-system agreement (ICC, >0.80), and nearly all ROI sizes demonstrated an almost perfect degree of intra- and inter-operator agreement (ICC, >0.80). The measurement reliability was higher when the acquisition angles were no more than 20°. The 3 machines had different SWS values. Attention should be paid when comparing SWS results using different machines. For the Aixplorer system, the ROI size had no effect on the SWS values. Angles larger than 25° will lead to SWS measurements with greater variability compared to smaller angles (≤20°).

The Accuracy of Ultrasound Shear Wave Elastography in the Diagnosis of Adenomyosis

The Accuracy of Ultrasound Shear Wave Elastography in the Diagnosis of Adenomyosis

How to perform shear wave elastography. Part II.

Recently a series of papers was introduced describing on "how to do" certain techniques. More specifically we published on how to perform strain imaging using the transcutaneous and endoscopic ultrasound approach and shear wave elastography (SWE). In the first part we describe how to optimize the examination technique, discussing normal values, pitfalls, artefacts and specific tips for applying SWE to specific organs (liver, breast, thyroid, salivary glands) as part of a diagnostic US examination. In part II, the use of SWE in the pancreas, spleen, kidney, prostate, scrotum, musculoskeletal system, lymph nodes and future developments are discussed.

Quantitative shear wave elastography compared to standard ultrasound (qualitative B-mode grayscale sonography and quantitative power Doppler) for evaluation of achillotendinopathy in treatment-naïve individuals: A cross-sectional study.

Achillotendinopathy is reported as an overuse disorder and/or degeneration change of the tendon. The diagnosis of tendinopathy is not always easy through imaging modalities. The B-mode grayscale sonography and power Doppler are well-established methods aimed at visualising tendon structure, but have limited sensitivity and lack conventional sonographic characteristics in symptomatic patients. Shear wave ultrasound elastography quantitatively assesses tissue stiffness. To compare the diagnostic accuracy of shear wave ultrasound elastography to that of standard ultrasound (combined B-mode grayscale sonography and power Doppler) for diagnosis of achillotendinopathy, considering clinical symptoms as the reference standard. Standard questionnaires regarding medical history and the Chinese version of a Victorian Institute of Sports Assessment - Achilles Questionnaires (VISA-AC) score were evaluated for a total of 14 treatment-naïve patients with complaints of localized swelling, and reduced force and/or flexibility of the Achilles tendon(s). The irregular thickening around the Achilles tendon, heterogeneity of echotexture of the tendon and calcification of the calcaneal attachment were considered incidences of tendinopathy in B-mode grayscale sonography. Tendinopathies were considered if tendons were >0.60 cm thick in power Doppler. Shear wave elasticity <350 kpa (10 m/s) was considered tendinopathy. A total of 28 conditions of both sides were evaluated through standard ultrasound examinations. Eighty-four tendons were assessed using shear wave ultrasound elastography. Asymptomatic tendons were visible as red and symptomatic (VISA-AC score <80) tendons were visible as blue or turquoise in the images. The rigidity of symptomatic tendons was lower than that of asymptomatic tendons (p < 0.0001). Sensitivity and accuracy for standard ultrasound were increased by the addition of shear wave ultrasound elastography for both symptomatic and asymptomatic tendons. The VISA-AC score was strongly correlated with the elasticity values (p = 0.000, Kendall's tau-beta (τβ) = 0.71) of Achilles tendons. Shear wave ultrasound elastography augments diagnostic confidence of standard ultrasound for the treatment of tendinopathies of Achilles tendons.