Research on Multiple-Factor Dynamic Constitutive Model of Poured Asphalt Concrete.

This study conducted dynamic triaxial tests on a typical poured asphalt concrete material of core walls in Xinjiang, exploring the dynamic characteristics of poured asphalt concrete under various confining pressures, principal stress ratios, and vibration frequencies. On this basis, the dynamic constitutive relationship of poured asphalt concrete was investigated using the Hardin-Drnevich model. The results indicate that under different confining pressures, principal stress ratios, and vibration frequencies, the variation patterns of the backbone lines of dynamic stress-strain of poured asphalt concrete are basically identical, consistent with a hyperbolic curve. The confining pressure and principal stress ratio significantly affect the backbone line of dynamic stress-strain. By comparison, frequency has a minimal effect. The changing trends of dynamic elasticity modulus and damping ratio of poured asphalt concrete under various factors are almost the same. When the material has high dynamic stress and strain, the hysteresis loop is large. When the curve of the damping ratio becomes flat, the asymptotic constant can be used as the maximum damping ratio. The relationship between the reciprocal of the dynamic elasticity modulus and the dynamic strain of poured asphalt concrete exhibits a linear distribution. Under different ratios of confining pressure to principal stress, there are large discrepancies between the calculated values from the formula and the experimental fitting values of the maximum dynamic elasticity modulus, and the maximum relative errors reach 16.65% and 18.15%, respectively. Therefore, the expression for the maximum dynamic elasticity modulus was modified, and the calculated values using the modified formula were compared with the experimental fitting values. The relative errors are significantly reduced, and the maximum relative errors are 3.02% and 2.04%, respectively, in good agreement with the fitting values of the experimental data. The findings of this article render a theoretical basis and reference for the promotion and application of poured asphalt concrete.

[Reconstruction of elasticity modulus distribution base on semi-supervised neural network].

Accurate reconstruction of tissue elasticity modulus distribution has always been an important challenge in ultrasound elastography. Considering that existing deep learning-based supervised reconstruction methods only use simulated displacement data with random noise in training, which cannot fully provide the complexity and diversity brought by in-vivo ultrasound data, this study introduces the use of displacement data obtained by tracking in-vivo ultrasound radio frequency signals (i.e., real displacement data) during training, employing a semi-supervised approach to enhance the prediction accuracy of the model. Experimental results indicate that in phantom experiments, the semi-supervised model augmented with real displacement data provides more accurate predictions, with mean absolute errors and mean relative errors both around 3%, while the corresponding data for the fully supervised model are around 5%. When processing real displacement data, the area of prediction error of semi-supervised model was less than that of fully supervised model. The findings of this study confirm the effectiveness and practicality of the proposed approach, providing new insights for the application of deep learning methods in the reconstruction of elastic distribution from in-vivo ultrasound data.

Biomechanical Analysis of Axial Gradient Porous Dental Implants: A Finite Element Analysis.

The porous structure can reduce the elastic modulus of a dental implant and better approximate the elastic characteristics of the material to the alveolar bone. Therefore, it has the potential to alleviate bone stress shielding around the implant. However, natural bone is heterogeneous, and, thus, introducing a porous structure may produce pathological bone stress. Herein, we designed a porous implant with axial gradient variation in porosity to alleviate stress shielding in the cancellous bone while controlling the peak stress value in the cortical bone margin region. The biomechanical distribution characteristics of axial gradient porous implants were studied using a finite element method. The analysis showed that a porous implant with an axial gradient variation in porosity ranging from 55% to 75% was the best structure. Under vertical and oblique loads, the proportion of the area with a stress value within the optimal stress interval at the bone-implant interface (BII) was 40.34% and 34.57%, respectively, which was 99% and 65% higher compared with that of the non-porous implant in the control group. Moreover, the maximum equivalent stress value in the implant with this pore parameter was 64.4 MPa, which was less than 1/7 of its theoretical yield strength. Axial gradient porous implants meet the strength requirements for bone implant applications. They can alleviate stress shielding in cancellous bone without increasing the stress concentration in the cortical bone margin, thereby optimizing the stress distribution pattern at the BII.

Role of galectin-3 in the elastic response of radial growth phase melanoma cancer cells.

Melanoma is originated from the malignant transformation of the melanocytes and is characterized by a high rate of invasion, the more serious stage compromising deeper layers of the skin and eventually leading to the metastasis. A high mortality due to melanoma lesion persists because most of melanoma lesions are detected in advanced stages, which decreases the chances of survival. The identification of the principal mechanics implicated in the development and progression of melanoma is essential to devise new early diagnosis strategies. Cell mechanics is related with a lot of cellular functions and processes, for instance motility, differentiation, migration and invasion. In particular, the elastic modulus (Young's modulus) is a very explored parameter to describe the cell mechanical properties; most cancer cells reported in the literature smaller elasticity modulus. In this work, we show that the elastic modulus of melanoma cells lacking galectin-3 is significantly lower than those of melanoma cells expressing galectin-3. More interestingly, the gradient of elastic modulus in cells from the nuclear region towards the cell periphery is more pronounced in shGal3 cells. RESEARCH HIGHLIGHTS: AFM imaging and force spectroscopy were used to investigate the morphology and elasticity properties of healthy HaCaT cells and melanoma cells WM1366, with (shSCR) and without (shGal3) expression of galectin-3. It is shown the effect of galectin-3 protein on the elastic properties of cells: the cells without expression of galectin-3 presents lower elastic modulus. By the results, we suggest here that galectin-3 could be used as an effective biomarker of malignancy in both melanoma diagnostic and prognosis.

Analysis of phellinus igniarius effects on gastric cancer cells by atomic force microscopy.

Gastric cancer is one of the common malignant tumors in the world, which originates from the gene mutation of human cells. In this work, an atomic force microscope was used to quantitatively detect the changes of multiple physical parameters such as the cell morphology, surface roughness, elasticity modulus and adhesion force before and after Phellinus linteus stimulation. The experimental results show that Phellinus linteus can change the shape of gastric cancer cells (SGC-7901) from flat to spherical, and increase their height and surface roughness values. The adhesion force of cells is reduced and the elasticity modulus is increased. But there are no significant differences in the morphology and mechanical properties of gastric epithelial cells (GES-1). The results indicate that Phellinus linteus has a high anticancer effect on the gastric cancer cells, but has less toxic side effects on the gastric epithelial cells. This work proves that Phellinus linteus can be used as a preferred anticancer drug for the treatment of gastric cancer cells.

Mussel-Inspired Calcium Alginate/Polyacrylamide Dual Network Hydrogel: A Physical Barrier to Prevent Postoperative Re-Adhesion.

Intrauterine adhesions (IUA) has become one of the main causes of female infertility. How to effectively prevent postoperative re-adhesion has become a clinical challenge. In this study, a mussel-inspired dual-network hydrogel was proposed for the postoperative anti-adhesion of IUA. First, a calcium alginate/polyacrylamide (CA-PAM) hydrogel was prepared via covalent and Ca2+ cross-linking. Benefiting from abundant phenolic hydroxyl groups, polydopamine (PDA) was introduced to further enhance the adhesion ability and biocompatibility. This CA-PAM hydrogel immersed in 10 mg/mL dopamine solution possessed remarkable mechanical strength (elastic modulus > 5 kPa) and super stretchability (with a breaking elongation of 720%). At the same time, it showed excellent adhesion (more than 6 kPa). Surprisingly, the coagulation index of the hydrogel was 27.27 ± 4.91, demonstrating attractive coagulation performance in vitro and the potential for rapid hemostasis after surgery.

Response of Apple Flesh to Compression under the Quasi-Static and Impact Loading Conditions.

Compression tests of cylindrical samples were carried out using two 'Rubin' and 'Red Jonaprince' apple cultivars with flesh firmness differing in a statistically significant way. The tests were conducted under both the quasi-static and impact loading conditions, which required the use of two test stands. For this purpose, an impact measuring stand was designed and built. The tests proved that the firmness of the apple flesh influenced the mechanical response under both the quasi-static and impact loading conditions. The elasticity modulus had much higher values under the impact than quasi-static loading conditions. This indicates that the stiffness of the apple tissue was larger during the impact than at the low-speed compression. Different failure mechanisms of cylindrical apple flesh samples were found depending on the loading conditions. Under the quasi-static loading conditions, the apples of both cultivars were damaged at the same strain value. However, during the impact, apples were apt to damage at a constant stress value regardless of the firmness of the tested cultivar. The toughness of the apple tissue depended on firmness and was larger under the quasi-static loading conditions for the apples with larger firmness. However, under the impact loading conditions, the toughness was greater for the apples with smaller firmness.

Reference values of the carotid elastic modulus using shear wave elastography and arterial stiffness change in coronary slow flow.

PURPOSE: Shear wave elastography (SWE) accurately and sensitively evaluates arterial wall stiffness by quantifying the elastic modulus (EM); however, the absence of reference values has precluded its widespread clinical application. This prospective cohort study aimed to establish reference values for the carotid EM using SWE; investigate the main determinants of the EM; and evaluate EM changes in coronary slow flow (CSF), which is characterized by delayed coronary opacification without evident obstructive lesion in epicardial coronary artery on angiography. METHOD: This study enrolled 169 healthy volunteers and 30 patients with CSF. The carotid maximum EM (EMmax), mean EM, and minimum EM were measured using SWE. CSF was diagnosed by thrombolysis in the myocardial infarction frame count during coronary angiography. RESULTS: No differences were found in the EM between the left and right carotid arteries and between men and women. Multiple linear regression analysis revealed that age was independently correlated with the EMmax, which progressively increased with age. Moreover, smoking had an independent influence on the EM after adjusting for age; smokers had higher EM than non-smokers. Age-specific reference values for the carotid EM were established. The EM was higher in patients with CSF than in controls after adjusting for age and smoking status. CONCLUSIONS: This study first established the reference values for the carotid EM using SWE. Age and smoking status were the main determinants of the EM. Patients with CSF had high EM. SWE can effectively and noninvasively evaluate arterial stiffness in patients with CSF.

Compressive Properties and Degradable Behavior of Biodegradable Porous Zinc Fabricated with the Protein Foaming Method.

A new protein foaming-consolidation method for preparing porous zinc was developed using three proteins (egg white protein (EWP), bovine bone collagen protein (BBCP), and fish bone collagen protein (FBCP)) as both consolidating and foaming agents. The preparation route utilized powder mixing and sintering processing, which could be divided into three steps: slurry preparation, low-temperature foaming, and high-temperature sintering. The morphological characteristics of the pore structures revealed that the porous zinc had an interconnected open-cell structure. Compared to the porous zinc prepared with EWP or BBCP, the porous zinc prepared with FBCP possessed the largest average pore size and the highest compressive properties. The porosity of the porous zinc increased with the stirring time, the content of protein and sucrose, and higher sintering temperatures. Moreover, a compression test and immersion test were performed to investigate the stress-strain behavior and corrosion properties of the resulting porous zinc. A fluctuated stress plateau could be found due to the brittle fracture of the porous cells. The porous zinc prepared with FBCP showed the highest compressive strength and elastic modulus. The corrosion rate of the porous zinc obtained through an immersion test in vitro using simulated bodily fluids on the thirty-second day was close to 0.02 mm/year. The corresponding corrosion mechanism of porous zinc was also discussed.

Investigation of HUVEC response to exposure to PAMAM dendrimers - changes in cell elasticity and vesicles release.

The aim of this study is to assess the effect of PAMAM dendrimers of second, fourth, and seventh generations on human umbilical vein endothelial cells. Primary endothelial cells were exposed to PAMAM dendrimers for 24 h, using concentrations reducing cellular viability to the levels of 90, 75, and 50%. We assumed, that changes in mechanical properties reflect toxicity of PAMAM dendrimers. The mechanical properties were investigated using atomic force spectroscopy (AFS) technique with the use of two approaches for measuring cell elasticity: global, where the tests were performed using a micrometer-hemispherical probe, and local, where a nanometer-sized probe was used. For the sharp probe, a reduction in the elasticity modulus was observed in comparison to untreated control cells, that is related to the depolymerization of the cytoskeleton and the processes leading to cell apoptosis. In the case of the hemispherical probe, cell softening was also observed in comparison to control cells, but with increasing PAMAM concentrations, the modulus of elasticity increases. It is related to the sensing of numerous intracellular vesicles with the use of this probe, e.g. endosomal and empty plasmalemmal which can also alter cell elasticity. The presence of external and intracellular vesicles was confirmed by scanning and transmission electron microscopy. The relationship between the elasticity of HUVEC cells exposed to PAMAM dendrimers of selected generations and their toxic effects was presented herein for the first time. In the transmission electron microscopy images of the cells exposed to PAMAM dendrimers, we have also observed distinctive vesicles with regular multilayer arranged structure.

Concrete Elastic Modulus Experimental Research Based on Theory of Capillary Tension.

The risk of cracking in the early stage is a critical indicator of the performance of concrete structures. Concrete cracked when the tensile stresses caused by deformation under restraint conditions exceeded its tensile strength. This research aims at an accurate prediction of shrinkage cracking of concrete under constraints. Based on the theory of capillary tension under the concrete shrinkage mechanism, the method to test and compute the elastic modulus of a micro-matrix around the capillary, Et, was derived. Shrinkage and porosity determination tests were conducted to obtain the shrinkage values and confining stresses of concrete at different strength grades, different ages and under different restraint conditions, accordingly. Meanwhile, the proposed method of this research was used to obtain Et. The restraint stress given by Et was compared with the experimental result under the corresponding time. The results suggested a positive correlation between the elastic modulus of a micro-matrix around the capillary, Et, precomputed by the theory, and the static elastic modulus, Ec, and that the ratio between the two gradually decreased with the passage of time, which ranged from 2.8 to 3.1.

Flatwise to Upright Build Orientations under Three-Point Bending Test of Nylon 12 (PA12) Additively Manufactured by SLS.

This paper describes in detail a series of static tests conducted in a three-point bend configuration on three build orientations (i.e., 0°, 45°, and 90°) of additively manufactured Nylon 12 (PA12) specimens produced with a powder refresh ratio of 50%, using a benchtop industrial SLS platform, Formlabs Fuse 1. The bending strength and flexural elasticity moduli are determined following ISO 173 specifications and by employing a more complex equation that considers the influence of large deflections as per ISO 14125 indications. Statistical variability of experimental data is considered and compared to the results from the literature. Through a fractographic SEM study, the damage morphologies of tested specimens are analyzed and associated with the recorded load-deflection curves for an accurate perception of build orientation-dependent anisotropy in bending properties of AM PA12 SLS specimens. A surprising result of this investigation is that the specimens built with 45° orientation showed superior modulus elasticity in flexure but a low bending strength compared to flatwise oriented specimens. In addition, a Weibull reliability quantification of bending strength is adapted to pinpoint the effects of internal 3D printing flaws (contained within a characteristic highly-stressed volume of material) over the failure probability of the three build orientations in question.

Solid Particle Erosion of Filled and Unfilled Epoxy Resin at Room and Elevated Temperatures.

Solid particle erosion at room and elevated temperatures of filled and unfilled hot-cured epoxy resin using an anhydride hardener were experimentally tested using an accelerated method on a special bench. Micro-sized dispersed industrial wastes were used as fillers: fly ash from a power plant and spent filling material from a copper mining and processing plant. The results showed that the wear of unfilled epoxy resin significantly decreases with increasing temperature, while the dependence on the temperature of the wear intensity at an impingement angle of 45° is linear and inversely proportional, and at an angle of 90°, non-linear. The decrease in wear intensity is probably due to an increase in the fracture limit because of heating. Solid particle erosion of the filled epoxy compounds is considerably higher than that of unfilled compounds at impingement angles of 45° and 90°. Filled compounds showed ambiguous dependences of the intensity of wear on temperature (especially at an impingement angle of 45°), probably as the dependence is defined by the filler share and the structural features of the samples caused by the distribution of filler particles. The intensity of the wear of the compounds at impingement angles of 45° and 90° has a direct and strong correlation with the density and the modulus of elasticity, and a weak correlation with the bending strength of the materials. The data set for determining the correlation between the mechanical properties and the wear included compound filling characteristics and temperature.

Comparison of restorative materials and surface alterations after prebiotic and probiotic beverages: A nanoindentation and SEM study.

The purpose was to investigate the surface characteristics of various resin-based materials by immersing in probiotic beverages. A total of 420 disc-shaped samples (5 mm × 2 mm) were prepared from resin-based composites. Samples were divided into four groups and immersed for 10 min/day for 1 month in either a probiotic sachet, kefir, kombucha, or artificial saliva (control). Surface roughness was measured at baseline and 1 month. One sample of each of the tested materials was examined under nanoindentation to evaluate the reduced elasticity modulus and nanohardness scores. Scanning electron microscopy (SEM) was used to compare surface differences. Data were analyzed statistically using one-way ANOVA test and the significance was set at p < .05. The lowest roughness scores were observed in Z250, Estelite Bulk Fill, and HRi ENA in most of the test groups. Among conventional composites, Z250 group had the highest nanohardness and elasticity modulus scores. Among bulk-fill composites, Estelite Bulk Fill Flow had the lowest surface roughness after immersion in probiotic beverages and the highest nanohardness values. Reveal HD, as a bulk-fill group showed higher surface roughness and considerably lower nanohardness and elasticity modulus scores. Maximum height levels of samples were recorded. SEM images revealed voids and microcracks on the surfaces of test materials. Dentists may prefer Z250 as microhybrid and Estelite Bulk Fill Flow as bulk-fill composites for the restorations of patients who consume gut-friendly drinks regularly. When there are various types of materials, nanoindentation is a useful method for evaluating surface alterations and sensible comparisons.

Effects of dynamic pressure on the proliferation and mechanical properties of rabbit adipose mesenchymal stem cells transfected with insulin-like growth factor-1 / 中国组织工程研究

BACKGROUND: Adipose mesenchymal stem cells are currently recognized as excellent seed cells for tissue engineering cartilage. Gene transfection technology can effectively induce them to differentiate into cartilage. The bioreactor is used to simulate the mechanical environment in vivo. It is a new idea for the majority of scholars to explore the construction of tissue engineering cartilage in vitro. OBJECTIVE: To investigate the effects of cyclic dynamic compressive stress combined with insulin-like growth factor-1 gene transfection on the proliferation and elastic modulus of rabbit adipose mesenchymal stem cells implanted in chitosan/gelatin scaffold. METHODS: Rabbit adipose mesenchymal stem cells were transfected with pcDNA3.1-IGF-1 gene mediated by liposome. The stable transfected cell lines were screened by G418. The adipose mesenchymal stem cells transfected with or without insulin-like growth factor-1 gene were inoculated in chitosan/ gelatin scaffold at the density of 5×1010 L-1 for 2 days, and cultured under dynamic pressure (2% at 1 Hz, 4 hours per day) or static culture conditions for 7 days, respectively. The morphological changes of the cell/scaffold complex were observed by scanning electron microscope, Masson trichrome staining and alcian blue staining. The cell proliferation curve was drawn by MTT assay. The cell proliferation efficiency and distribution were evaluated by CM-Dil fluorescence-labeling method, and the content of total glycosaminoglycan was quantitatively determined by DMMB. The differences of type II collagen among different groups were compared with real time PCR. Compressive mechanical properties of the cell/scaffold constructs were assessed using a BioDynamic™ mechanical tester, and the corresponding elastic modulus was calculated. RESULTS AND CONCLUSION: Dynamic pressure combined with insulin-like growth factor-1 transfection could significantly improve the cell proliferation ability of the cell/scaffold complex; the cell distribution was more uniform; glycosaminoglycan and collagen secretion in the cartilage-specific extracellular matrix were increased; the expression levels of type II collagen were up-regulated; and the mechanical properties were significantly improved. The cell proliferation and elastic modulus of insulin-like growth factor-1 group were better than those of single pressure group, but the distribution of cells in scaffolds was more uniform under dynamic pressure. The results indicate that both dynamic pressure and insulin-like growth factor-1 gene transfection can significantly improve the proliferation and mechanical properties of rabbit adipose mesenchymal stem cells; the two have synergistic effect.

Preliminary study on mechanical characteristics of maxillofacial soft and hard tissues for virtual surgery.

PURPOSE: Virtual surgery system can provide us a realistic and immersive training environment, in which haptic force-feedback gives operators 'touching feeling.' Appropriate deformation models of soft and hard tissues are required for the achievement of real-time haptic feedback. To improve accuracy of modeling and haptic feedback simulation for maxillofacial virtual surgery, mechanical characteristics of soft and hard tissues should be explored. METHODS: Craniofacial soft tissues from one male and female cadavers were divided into two layers: skin and muscle. Maxillofacial tissues were divided into frontal, chin, temporalis, masseter regions. Insertion and cutting process were conducted using VMX42 5-axis linkage system and recorded by piezoelectric dynamometer. Maximum stiffness values were analyzed, and insertion curves before puncture were fitted using a polynomial model. Elasticity modulus and hardness of maxillofacial hard tissues were measured and analyzed using Berkovich nanoindentation. RESULTS: Tissues in different maxillofacial regions, as well as from different layers (skin and muscle), displayed various mechanical performance. Maximum stiffness values and cutting force of soft tissues in male and female had significant difference. The third-order polynomial was demonstrated to fit the insertion curves well before puncture. Furthermore, elasticity modulus and hardness of enamel were significantly greater than that of zygoma, maxilla and mandible. CONCLUSION: Mechanical properties of hard tissues are relatively stable, which can be applied in virtual surgery system for physical model construction. Insertion model and cutting force for soft tissues are meaningful and applicable and can be utilized to promote the accuracy of response for haptic feedback sensations.

Longitudinal and Transversal Elasticity of Natural and Artificial Materials for Musical Instrument Reeds.

The reed is the primary component in single-reed woodwind instruments to generate the sound. The airflow of the player's mouth is the energy source and the airflow is modulated by the reed. The oscillations of the reed control the airflow. Traditionally, instrument reeds are made out of natural cane (Arundo Donax), but in efforts to overcome variability problems, synthetic reeds have been introduced. Previous investigations mainly focused on natural cane reeds and direct elasticity measurements did not discriminate between elasticity moduli along different directions. In order to obtain the mechanical properties along the direction of the reed fibres and in the orthogonal direction separately, a three-point bending testing setup was developed, which accommodates the small samples that can be cut from an instrument reed. Static moduli of elasticity were acquired in both directions. Much higher ratios between longitudinal and transversal moduli were seen in the natural cane reed as compared to the artificial reeds. Wet natural reeds showed a strong decrease in moduli of elasticity as compared to dry reeds. Elasticity was significantly higher in artificial reeds. The force-displacement curves of the wet natural reed show hysteresis, whereas the artificial materials did not. In the cane reed, higher energy losses were found in the transversal direction compared to the longitudinal direction.

Modulus and Strength of Concretes with Alternative Materials.

This paper presents a study with concretes produced with natural aggregates, recycled concrete aggregates (RCA) and waste porcelain aggregates (WPA). The study analyzed the influence of recycled aggregates in the mechanical properties of conventional concretes and evaluated the difference between measured and predicted values of elasticity modulus. The incorporation of WPA in concrete showed better mechanical results compared to the concretes produced with RCA. Measured elasticity moduli were lower than moduli predicted by NBR 6118:2014 and fib Model Code 2010, while measured results were greater than values predicted by Eurocode 2:2004 and ACI 318:2014, as expected, which indicated the safety of the latter two standards.

The role of real-time shear wave elastography in the diagnosis of idiopathic nephrotic syndrome and evaluation of the curative effect.

PURPOSE: To evaluate the use of real-time shear wave elastography (SWE) in the assessment of renal elasticity and the efficacy of steroid treatment in adult idiopathic nephrotic syndrome (INS). METHODS: This study included 120 patients with INS. Patients were divided into steroid-sensitive and steroid-resistant groups. Renal biopsy was performed. Thirty healthy subjects were recruited as controls. Young's modulus (YM) of the renal parenchyma was measured by SWE. The YM values in each group were compared using glomerular sclerosis index (GI) and renal interstitial fibrosis (RIF). RESULTS: The YM values were significantly different between the INS and control groups, as well as between the steroid-sensitive and steroid-resistant groups (P < 0.05). Higher YM values were associated with steroid sensitivity. The area under the receiver operating characteristic curve for the YM value in the INS group vs. control group was 0.871 (95% CI 0.815-0.927) and in the steroid-resistant group vs. control, and steroid-sensitive groups was 0.836 (95% CI 0.765-0.908). The corresponding cut-off values were 7.96 and 10.73 m/s, with 81.7% and 86.0% sensitivities, 93.3% and 77.9% specificities, and Youden index 0.750 and 0.639, respectively. Spearman correlation analysis showed that the YM value in the renal parenchyma was positively correlated with GI (r = 0.631, P < 0.05) and RIF (r = 0.606, P < 0.05). CONCLUSION: SWE technology is a potential method for non-invasive quantitative measurement of renal parenchyma stiffness to determine the pathological changes of INS renal parenchyma and evaluate the effectiveness of steroid therapy.

The effect of regions-of-interest and elasticity modulus selection on differentiating benign and malignant cervical lymph nodes with shear wave elastography

OBJECTIVE: Imaging diagnosis of cervical lymphadenopathy has conventionally used ultrasonography. Shear wave elastography (SWE) is a recent ultrasound technological advancement that has shown promise in the important medical problem of differentiating between benign and malignant cervical lymph nodes based on quantitative measurements of elasticity modulus. However, widely varying elasticity modulus metrics and regions-of-interest (ROIs) were used in existing studies, leading to inconsistent findings and results that are hard to compare with each other. METHODS: Using a large dataset of 264 cervical lymph nodes from 200 patients, we designed a study comparing three elasticity modulus metrics (Emax, Emean, and standard deviation-SD) with three different ROIs to evaluate the effect of such selections. The metric values were compared between the benign and malignant node groups. The different ROI and metric selections were also compared through receiver operating characteristics curve analysis. RESULTS: For all ROIs, all metric values were significantly different between the two groups, indicting their diagnostic potential. This was confirmed by the ≥0.80 area under the curve (AUC) values achieved with these metrics. Different ROIs had no effect on Emax, whereas all ROIs achieved high performance at 0.88 AUC. For Emean, the smallest ROI focusing on the area of the highest elasticity achieved the best diagnostic performance. In contrast, the larger ROIs achieved higher performances for SD. CONCLUSIONS: This study illustrated the effect of elasticity modulus and ROI selection on the diagnostic performance of SWE on cervical lymphadenopathy. These new findings help guide relevant future studies and clinical applications of this important quantitative imaging modality.