This study explores the significance of using two-dimensional shear wave elastography(2D-SWE)to assess liver stiffness(LS)and spleen area(SPA)for predicting post-hepatectomy liver failure(PHLF).By providing a non-inva...This study explores the significance of using two-dimensional shear wave elastography(2D-SWE)to assess liver stiffness(LS)and spleen area(SPA)for predicting post-hepatectomy liver failure(PHLF).By providing a non-invasive method to measure LS,which correlates with the degree of liver fibrosis,and SPA,an indicator of portal hypertension,2D-SWE offers a comprehensive evaluation of a patient’s hepatic status.These advancements are particularly crucial in hepatic surgery,where accurate preoperative assessments are essential for optimizing surgical outcomes and minimizing complications.This letter highlights the prac-tical implications of integrating 2D-SWE into clinical practice,emphasizing its potential to improve patient safety and surgical precision by enhancing the ability to predict PHLF and tailor surgical approaches accordingly.展开更多
BACKGROUND Thyroid dysfunction during pregnancy is an important disease affecting the health of mothers and children.Two-dimensional(2D)shear wave elastography(SWE)is the newest ultrasonic elastography technology and ...BACKGROUND Thyroid dysfunction during pregnancy is an important disease affecting the health of mothers and children.Two-dimensional(2D)shear wave elastography(SWE)is the newest ultrasonic elastography technology and its value in differentiating benign and malignant thyroid nodules has been widely recognized.However,the value of 2D SWE in evaluating and predicting thyroid function is unclear.AIM To explore prospectively the value of 2D SWE quantitative analysis for the evaluation of thyroid function in the first trimester.METHODS We included outpatients of reproductive age in the Department of Gynecology in Shanghai Changning Maternity and Infant Health Hospital between March 2023 and March 2024 who had conventional ultrasound examination and 2D SWE of the thyroid.They also underwent transvaginal ultrasound examination to confirm early intrauterine pregnancy and serum thyroid stimulating hormone(TSH)level was measured.The patients were divided into pregnant with normal TSH,pregnant with abnormal TSH,and nonpregnant with normal TSH.Conventional ultrasound and 2D SWE results were compared among the three groups.RESULTS A total of 108 patients were included in the study;57 in the pregnant with normal TSH group,18 in the pregnant with abnormal TSH group and 33 were in the nonpregnant with normal TSH group.Thyroid size,thyroid echotexture,2D SWE quantitative parameters including mean elasticity in the region of interest and maximal elasticity in the region of interest showed no significant differences among the three groups(P>0.05).CONCLUSION Conventional ultrasound and 2D SWE features could not reflect the level of serum TSH.展开更多
BACKGROUND The clinical management and prognosis differ between benign and malignant solid focal liver lesions(FLLs),as well as among different pathological types of malignant FLLs.Accurate diagnosis of the possible t...BACKGROUND The clinical management and prognosis differ between benign and malignant solid focal liver lesions(FLLs),as well as among different pathological types of malignant FLLs.Accurate diagnosis of the possible types of solid FLLs is important.Our previous study confirmed the value of shear wave elastography(SWE)using maximal elasticity(Emax)as the parameter in the differential diagnosis between benign and malignant FLLs.However,the value of SWE in the differential diagnosis among different pathological types of malignant FLLs has not been proved.AIM To explore the value of two-dimensional SWE(2D-SWE)using Emax in the differential diagnosis of FLLs,especially among different pathological types of malignant FLLs.METHODS All the patients enrolled in this study were diagnosed as benign,malignant or undetermined FLLs by conventional ultrasound.Emax of FLLs and the periphery of FLLs was measured using 2D-SWE and compared between benign and malignant FLLs or among different pathological types of malignant FLLs.RESULTS The study included 32 benign FLLs in 31 patients and 100 malignant FLLs in 96 patients,including 16 cholangiocellular carcinomas(CCCs),72 hepatocellular carcinomas(HCCs)and 12 liver metastases.Thirty-five FLLs were diagnosed as undetermined by conventional ultrasound.There were significant differences between Emax of malignant(2.21±0.57 m/s)and benign(1.59±0.37 m/s)FLLs(P=0.000),and between Emax of the periphery of malignant(1.52±0.39 m/s)and benign(1.36±0.44 m/s)FLLs(P=0.040).Emax of liver metastases(2.73±0.99 m/s)was significantly higher than that of CCCs(2.14±0.34 m/s)and HCCs(2.14±0.46 m/s)(P=0.002).The sensitivity,specificity and accuracy were 71.00%,84.38%and 74.24%respectively,using Emax>1.905 m/s(AUC 0.843)to diagnose as malignant and 23 of 35(65.74%)FLLs with undetermined diagnosis by conventional ultrasound were diagnosed correctly.CONCLUSION Malignant FLLs were stiffer than benign ones and liver metastases were stiffer than primary liver carcinomas.2D-SWE with Emax was a useful complement to conventional ultrasound for the differential diagnosis of FLLs.展开更多
Two-dimensional shear wave elastography(2D-SWE)is used in the clinical setting for observation of the liver.Unfortunately,a wide spectrum of artifactual images are frequently encountered in 2D-SWE,the precise mechanis...Two-dimensional shear wave elastography(2D-SWE)is used in the clinical setting for observation of the liver.Unfortunately,a wide spectrum of artifactual images are frequently encountered in 2D-SWE,the precise mechanisms of which remain incompletely understood.This review was designed to present many of the artifactual images seen in 2D-SWE of the liver and to analyze them by computer simulation models that support clinical observations.Our computer simulations yielded the following suggestions:(1)When performing 2D-SWE in patients with chronic hepatic disease,especially liver cirrhosis,it is recommended to measure shear wave values through the least irregular hepatic surface;(2)The most useful 2D-SWE in patients with focal lesion will detect lesions that are poorly visible on B-mode ultrasound and will differentiate true tumors from pseudo-tumors(e.g.,irregular fatty change);and(3)Measurement of shear wave values in the area posterior to a focal lesion must be avoided.展开更多
BACKGROUND Post-hepatectomy liver failure(PHLF)increases morbidity and mortality after liver resection for patients with advanced liver fibrosis and cirrhosis.Preoperative liver stiffness using two-dimensional shear w...BACKGROUND Post-hepatectomy liver failure(PHLF)increases morbidity and mortality after liver resection for patients with advanced liver fibrosis and cirrhosis.Preoperative liver stiffness using two-dimensional shear wave elastography(2D-SWE)is widely used to evaluate the degree of fibrosis.However,the 2D-SWE results were not accurate.A durometer measures hardness by quantifying the ability of a material to locally resist the intrusion of hard objects into its surface.However,the durometer score can only be obtained during surgery.To measure correlations among 2D-SWE,palpation by surgeons,and durometermeasured objective liver hardness and to construct a liver hardness regression model.METHODS We enrolled 74 hepatectomy patients with liver hardness in a derivation cohort.Tactile-based liver hardness scores(0-100)were determined through palpation of the liver tissue by surgeons.Additionally,liver hardness was measured using a durometer.Correlation coefficients for durometer-measured hardness and preoperative parameters were calculated.Multiple linear regression models were constructed to select the best predictive durometer scale.Receiver operating characteristic(ROC)curves and univariate and multivariate analyses were used to calculate the best model’s prediction of PHLF and risk factors for PHLF,respectively.A separate validation cohort(n=162)was used to evaluate the model.RESULTS The stiffness measured using 2D-SWE and palpation scale had good linear correlation with durometer-measured hardness(Pearson rank correlation coefficient 0.704 and 0.729,respectively,P<0.001).The best model for the durometer scale(hardness scale model)was based on stiffness,hepatitis B virus surface antigen,and albumin level and had an R2 value of 0.580.The area under the ROC for the durometer and hardness scale for PHLF prediction were 0.807(P=0.002)and 0.785(P=0.005),respectively.The optimal cutoff value of the durometer and hardness scale was 27.38(sensitivity=0.900,specificity=0.660)and 27.87(sensitivity=0.700,specificity=0.787),respectively.Patients with a hardness scale score of>27.87 were at a significantly higher risk of PHLF with hazard ratios of 7.835(P=0.015).The model’s PHLF predictive ability was confirmed in the validation cohort.CONCLUSION Liver stiffness assessed by 2D-SWE and palpation correlated well with durometer hardness values.The multiple linear regression model predicted durometer hardness values and PHLF.展开更多
Objective:To explore the feasibility of two-dimensional shear wave elastography in evaluating calf skeletal muscle stiffness in diabetic nephropathy patients with medial tibial stress syndrome.Methods:A total of 48 di...Objective:To explore the feasibility of two-dimensional shear wave elastography in evaluating calf skeletal muscle stiffness in diabetic nephropathy patients with medial tibial stress syndrome.Methods:A total of 48 diabetic nephropathy patients with medial tibial stress syndrome from January 2020 to December 2022 were included as the study group,and 48 patients with diabetic nephropathy during the same period were included as the control group.Both groups were detected by two-dimensional shear wave elastography with ultrasonic equipment,and Young‘s modulus of the tibialis anterior muscle,tibialis posterior muscle,and gastrocnemius muscle were observed and analyzed in the two groups.Results:The Young‘s modulus values of tibialis anterior muscle,tibialis posterior muscle,and gastrocnemius muscle in the study group were significantly lower than those in the control group(P<0.05).Conclusion:Two-dimensional shear wave elastography is feasible for the evaluation of calf skeletal muscle stiffness in diabetic nephropathy patients with medial tibial stress syndrome,and has high accuracy and repeatability.This technique can be used to diagnose,treat and monitor muscle lesions in patients with diabetic nephropathy,and can also be used to assess muscle fatigue and exercise capacity,which has broad application prospects.展开更多
Two-dimensional shear wave elastography(2D-SWE) is a rapid, simple and novel noninvasive method that has been proposed for assessing hepatic fibrosis in patients with chronic liver diseases(CLDs) based on measurements...Two-dimensional shear wave elastography(2D-SWE) is a rapid, simple and novel noninvasive method that has been proposed for assessing hepatic fibrosis in patients with chronic liver diseases(CLDs) based on measurements of liver stiffness. 2 D-SWE can be performed easily at the bedside or in an outpatient clinic and yields immediate results with good reproducibility. Furthermore, 2 D-SWE was an efficient method for evaluating liver fibrosis in small to moderately sized clinical trials. However, the quality criteria for the staging of liver fibrosis are not yet well defined. Liver fibrosis is the main pathological basis of liver stiffness and a key step in the progression from CLD to cirrhosis; thus, the management of CLD largely depends on the extent and progression of liver fibrosis. 2 D-SWE appears to be an excellent tool for the early detection of cirrhosis and may have prognostic value in this context. Because 2 D-SWE has high patient acceptance, it could be useful for monitoring fibrosis progression and regression in individual cases. However, multicenter data are needed to support its use. This study reviews the current status and future perspectives of 2 D-SWE for assessments of liver fibrosis and discusses the technical advantages and limitations that impact its effective and rational clinical use.展开更多
Liver biopsy is the gold standard for evaluating the degree of liver fibrosis in patients with chronic liver disease. However, due to the many limitations of liver biopsy, there has been much interest in the use of no...Liver biopsy is the gold standard for evaluating the degree of liver fibrosis in patients with chronic liver disease. However, due to the many limitations of liver biopsy, there has been much interest in the use of noninvasive techniques for this purpose. Among these techniques real-time two-dimensional shear wave elastography(2D-SWE) has the advantage of measuring tissue elasticity with the guidance of B-mode images. Recently, many studies have been conducted on the application of 2D-SWE in patients with various liver diseases, and their validity has been confirmed. Here, we briefly discuss the role of 2D-SWE in patients with chronic liver diseases, particularly aspects of the examination techniques and clinical applications.展开更多
Background:Liver fibrosis is a common pathological change caused by a variety of etiologies.Early diagnosis and timely treatment can reverse or delay disease progression and improve the prognosis.This study aimed to a...Background:Liver fibrosis is a common pathological change caused by a variety of etiologies.Early diagnosis and timely treatment can reverse or delay disease progression and improve the prognosis.This study aimed to assess the potential utility of two-dimensional shear wave elastography and texture analysis in dynamic monitoring of the progression of liver fibrosis in rat model.Methods:Twenty rats were divided into control group(n=4)and experimental groups(n=4 per group)with carbon tetrachloride administration for 2,3,4,and 6 weeks.The liver stiffness measurement was performed by two-dimensional shear wave elastography,while the optimal texture analysis subsets to distinguish fibrosis stage were generated by MaZda.The results of elastography and texture analysis were validated through comparing with histopathology.Results:Liver stiffness measurement was 6.09±0.31 kPa in the control group and 7.10±0.41 kPa,7.80±0.93 kPa,8.64±0.93 kPa,9.91±1.13 kPa in the carbon tetrachloride induced groups for 2,3,4,6 weeks,respectively(P<0.05).By texture analysis,histogram and co-occurrence matrix had the most frequency texture parameters in staging liver fibrosis.Receiver operating characteristic curve of liver elasticity showed that the sensitivity and specificity were 95.0%and 92.5%to discriminate liver fibrosis and non-fibrosis,respectively.In texture analysis,five optimal parameters were selected to classify liver fibrosis and non-fibrosis.Conclusions:Two-dimensional shear wave elastography showed potential applications for noninvasive monitoring of the progression of hepatic fibrosis,even in mild fibrosis.Texture analysis can further extract and quantify the texture features in ultrasonic image,which was a supplementary to further visual information and acquired high diagnostic accuracy for severe fibrosis.展开更多
BACKGROUND Few systematic comparative studies of the different methods of physical elastography of the spleen are currently available.AIM To compare point shear wave and two-dimensional elastography of the spleen cons...BACKGROUND Few systematic comparative studies of the different methods of physical elastography of the spleen are currently available.AIM To compare point shear wave and two-dimensional elastography of the spleen considering the anatomical location(upper,hilar,and lower pole).METHODS As part of a prospective clinical study,healthy volunteers were examined for splenic elasticity using four different ultrasound devices between May 2015 and April 2017.The devices used for point shear wave elastography were from Siemens(S 3000)and Philips(Epiq 7),and those used for two-dimensional shear wave elastography were from GE(Logiq E9)and Toshiba(Aplio 500).In addition,two different software versions(5.0 and 6.0)were evaluated for the Toshiba ultrasound device(Aplio 500).The study consisted of three arms:A,B,and C.RESULTS In study arm A,200 subjects were evaluated(78 males and 122 females,mean age 27.9±8.1 years).In study arm B,113 subjects were evaluated(38 men and 75 women,mean age 26.0±6.3 years).In study arm C,44 subjects were enrolled.A significant correlation of the shear wave velocities at the upper third of the spleen(r=0.33088,P<0.0001)was demonstrated only for the Philips Epiq 7 device compared to the Siemens Acuson S 3000.In comparisons of the other ultrasound devices(GE,Siemens,Toshiba),no comparable results could be obtained for any anatomical position of the spleen.The influencing factors age,gender,and body mass index did not show a clear correlation with the measured shear wave velocities.CONCLUSION The absolute values of the shear wave elastography measurements of the spleen and the two different elastography methods are not comparable between different manufacturers or models.展开更多
Fractures play a crucial role in various fields such as hydrocarbon exploration,groundwater resources management,and earthquake research.The determination of fracture location and the estimation of parameters such as ...Fractures play a crucial role in various fields such as hydrocarbon exploration,groundwater resources management,and earthquake research.The determination of fracture location and the estimation of parameters such as fracture length and dip angle are the focus of geophysical work.In borehole observation system,the short distance between fractures and detectors leads to weak attenuation of elastic wave energy,and high-frequency source makes it easier to identify small-scale fractures.Compared to traditional monopole logging methods,dipole logging method has advantage of exciting pure shear waves sensitive to fractures,so its application is becoming increasingly widespread.However,since the reflected shear waves and scattered shear waves of fractures correspond to different fracture properties,how to distinguish and analyze these two kinds of waves is crucial for accurately characterizing the fracture parameters.To address this issue,numerical simulation of wave responses by a single fracture near a borehole in rock formation is performed,and the generation mechanism and characteristics of shear waves scattered by fractures are investigated.It is found that when the dip angle of the fracture surpasses a critical threshold,the S-wave will propagate to both endpoints of the fracture and generate scattered S-waves,resulting in two distinct scattered wave packets on the received waveform.When the polarization direction of the acoustic source is parallel to the strike of the fracture,the scattered SH-waves always have larger amplitude than the scattered SV-waves regardless of changing the fracture dip angle.Unlike SV-waves,the SH-waves scattered by the fracture do not have any mode conversion.Additionally,propagation of S-waves to a short length fracture can induce dipole mode vibration of the fracture within a wide frequency range.The phenomena of shear waves reflected and scattered by the fracture are further illustrated and verified by two field examples,thus showing the potential of scattered waves for fracture evaluation and characterization with borehole observation system.展开更多
BACKGROUND Integrating conventional ultrasound features with 2D shear wave elastography(2D-SWE)can potentially enhance preoperative hepatocellular carcinoma(HCC)predictions.AIM To develop a 2D-SWE-based predictive mod...BACKGROUND Integrating conventional ultrasound features with 2D shear wave elastography(2D-SWE)can potentially enhance preoperative hepatocellular carcinoma(HCC)predictions.AIM To develop a 2D-SWE-based predictive model for preoperative identification of HCC.METHODS A retrospective analysis of 884 patients who underwent liver resection and pathology evaluation from February 2021 to August 2023 was conducted at the Oriental Hepatobiliary Surgery Hospital.The patients were divided into the modeling group(n=720)and the control group(n=164).The study included conventional ultrasound,2D-SWE,and preoperative laboratory tests.Multiple logistic regression was used to identify independent predictive factors for RESULTS In the modeling group analysis,maximal elasticity(Emax)of tumors and their peripheries,platelet count,cirrhosis,and blood flow were independent risk indicators for malignancies.These factors yielded an area under the curve of 0.77(95%confidence interval:0.73-0.81)with 84%sensitivity and 61%specificity.The model demonstrated good calibration in both the construction and validation cohorts,as shown by the calibration graph and Hosmer-Lemeshow test(P=0.683 and P=0.658,respectively).Additionally,the mean elasticity(Emean)of the tumor periphery was identified as a risk factor for microvascular invasion(MVI)in malignant liver tumors(P=0.003).Patients receiving antiviral treatment differed significantly in platelet count(P=0.002),Emax of tumors(P=0.033),Emean of tumors(P=0.042),Emax at tumor periphery(P<0.001),and Emean at tumor periphery(P=0.003).CONCLUSION 2D-SWE’s hardness value serves as a valuable marker for enhancing the preoperative diagnosis of malignant liver lesions,correlating significantly with MVI and antiviral treatment efficacy.展开更多
BACKGROUND Real-time shear wave elastography(SWE)is a non-invasive imaging technique used to measure tissue stiffness by generating and tracking shear waves in real time.This advanced ultrasound-based method provides ...BACKGROUND Real-time shear wave elastography(SWE)is a non-invasive imaging technique used to measure tissue stiffness by generating and tracking shear waves in real time.This advanced ultrasound-based method provides quantitative information regarding tissue elasticity,offering valuable insights into the mechanical properties of biological tissues.However,the application of real-time SWE in the musculoskeletal system and sports medicine has not been extensively studied.AIM To explore the practical value of real-time SWE for assessing Achilles tendon hardness in older adults.METHODS A total of 60 participants were enrolled in the present study,and differences in the elastic moduli of the bilateral Achilles tendons were compared among the following categories:(1)Age:55-60,60-65,and 65-70-years-old;(2)Sex:Male and female;(3)Laterality:Left and right sides;(4)Tendon state:Relaxed and tense state;and(5)Tendon segment:Proximal,middle,and distal.RESULTS There were no significant differences in the elastic moduli of the bilateral Achilles tendons when comparing by age or sex(P>0.05).There were,however,significant differences when comparing by tendon side,state,or segment(P<0.05).CONCLUSION Real-time SWE plays a significant role compared to other examination methods in the evaluation of Achilles tendon hardness in older adults.展开更多
Elastography can be used as a diagnostic method for quantitative characterization of tissue hardness information and thus,differential changes in pathophysiological states of tissues.In this study,we propose a new met...Elastography can be used as a diagnostic method for quantitative characterization of tissue hardness information and thus,differential changes in pathophysiological states of tissues.In this study,we propose a new method for shear wave elastography(SWE)based on laser-excited shear wave,called photoacoustic shear wave elastography(PASWE),which combines photoacoustic(PA)technology with ultrafast ultrasound imaging.By using a focused laser to excite shear waves and ultrafast ultrasonic imaging for detection,high-frequency excitation of shear waves and noncontact elastic imaging can be realized.The laser can stimulate the tissue with the light absorption characteristic to produce the thermal expansion,thus producing the shear wave.The frequency of shear wave induced by laser is higher and the frequency band is wider.By tracking the propagation of shear wave,Young’s modulus of tissue is reconstructed in the whole shear wave propagation region to further evaluate the elastic information of tissue.The feasibility of the method is verified by experiments.Compared with the experimental results of supersonic shear imaging(SSI),it is proved that the method can be used for quantitative elastic imaging of the phantoms.In addition,compared with the SSI method,this method can realize the noncontact excitation of the shear wave,and the frequency of the shear wave excited by the laser is higher than that of the acoustic radiation force(ARF),so the spatial resolution is higher.Compared to the traditional PA elastic imaging method,this method can obtain a larger imaging depth under the premise of ensuring the imaging resolution,and it has potential application value in the clinical diagnosis of diseases requiring noncontact quantitative elasticity.展开更多
Liquefaction assessment based on strain energy is significantly superior to conventional stress-based methods.The main purpose of the present study is to investigate the correlation between shear wave velocity and str...Liquefaction assessment based on strain energy is significantly superior to conventional stress-based methods.The main purpose of the present study is to investigate the correlation between shear wave velocity and strain energy capacity of silty sands.The dissipated energy until liquefaction occurs was calculated by analyzing the results of three series of comprehensive cyclic direct simple shear and triaxial tests on Ottawa F65,Nevada,and Firoozkuh sands with varying silt content by weight and relative densities.Additionally,the shear wave velocity of each series was obtained using bender element or resonant column tests.Consequently,for the first time,a liquefaction triggering criterion,relating to effective overburden normalized liquefaction capacity energy(WL=s’c)to effective overburden stresscorrected shear wave velocity(eVs1)has been introduced.The accuracy of the proposed criteria was evaluated using in situ data.The results confirm the ability of shear wave velocity as a distinguishing parameter for separating liquefied and non-liquefied soils when it is calculated against liquefaction capacity energy(WL=s’c).However,the proposed WL=s’c-Vs1 curve,similar to previously proposed cyclic resistance ratio(CRR)-Vs1 relationships,should be used conservatively for fields vulnerable to liquefaction-induced lateral spreading.展开更多
The strength parameters of hydrate-bearing sediments(HBS)are vital to geological risk assessment and control during drilling and production operations.However,current publications mainly focus on the laboratory evalua...The strength parameters of hydrate-bearing sediments(HBS)are vital to geological risk assessment and control during drilling and production operations.However,current publications mainly focus on the laboratory evaluation of strength parameters through triaxial compression,generating results intrinsically deviating from those obtained through petrophysical modeling.In this study,we developed an integrated apparatus that can simultaneously measure wave velocity and the mechanical behaviors of HBS under triaxial compression conditions.A series of experiments were conducted to analyze correlations between wave velocities and strength parameters.Results reveal that the P-and S-wave velocities considerably increase with hydrate saturation and are affected by effective confining pressure.Failure strength and elastic modulus are correlated with P-wave velocity.Finally,semi-empirical models are developed to predict strength parameters based on P-wave velocity and extended to establish longitudinal profiles for strength parameters of hydrate reservoirs in the Nankai Trough.This study offers insights into the acoustic properties of HBS under stress states for the prediction of mechanical parameters during natural gas hydrate development.展开更多
Two new exact, rational and periodic wave solutions are derived for the two-dimensional Boussinesq equation. For the first solution it is obtained by performing an appropriate limiting procedure on the soliton solutio...Two new exact, rational and periodic wave solutions are derived for the two-dimensional Boussinesq equation. For the first solution it is obtained by performing an appropriate limiting procedure on the soliton solutions obtained by Hirota bilinear method. The second one in terms of Riemann theta function is explicitly presented by virtue of Hirota bilinear method and its asymptotic property is also analyzed in detail. Moreover, it is of interest to note that classical soliton solutions can be reduced from the periodic wave solutions.展开更多
The horizontal-to-vertical spectral ratio(HVSR)method has been used to characterize site-effect parameters that are indispensable in seismic hazard and risk-reduction studies in urban areas and rapid land-use planning...The horizontal-to-vertical spectral ratio(HVSR)method has been used to characterize site-effect parameters that are indispensable in seismic hazard and risk-reduction studies in urban areas and rapid land-use planning.This method is widely used because it is the cheapest and simplest geophysical method for the acquisition and processing stages.In subsequent developments,the HVSR method has been widely used to determine elastic rock parameters,particularly shear wave velocity(v_(S)),through the HVSR curve inversion process.Furthermore,the v_(S)structural model can be used to delineate the presence of complex geological structures,particularly faults and sedimentary basins.Bandar Lampung is a city in Lampung Province with many fault structures and groundwater basins to the south.There are 83 HVSR measurement points around Bandar Lampung for delineating the presence of fault structures and groundwater basins.We produced the HVSR curve from the measurement results and then performed an inversion process using the particle swarm optimization algorithm to obtain v_(S)for the depth profile.Subsequently,from this profile,we produced a two-dimensional(2D)lateral and vertical model.The mean v_(S)value was calculated from all the measurement points,and we found stiff soil layers reaching depths of approximately 5 m,with a value of v_(S)<330 m/s.A bedrock layer with a velocity exceeding 1250 m/s was visible at a depth of 100 m.Based on the 2D model,the v_(S)structure shows that the city of Bandar Lampung is divided into two zones,with a NW-SE boundary.The north-middle-eastern part of the city consists of harder rocks.This harder rock is characterized by extremely high v_(S)values,starting from a depth of 50 m.In contrast,the south-middle-west exhibits a low-moderate v_(S)anomaly associated with groundwater basins SW of the city.From the 2D v_(S)structural model,fault structures can be found along the city,characterized by a contrast of v_(S)values from low to medium and from medium to high.展开更多
Shear wave splitting(SWS)is regarded as the most effective geophysical method to delineate mantle flow fields by detecting seismic azimuthal anisotropy in the earth's upper mantle,especially in tectonically active...Shear wave splitting(SWS)is regarded as the most effective geophysical method to delineate mantle flow fields by detecting seismic azimuthal anisotropy in the earth's upper mantle,especially in tectonically active regions such as subduction zones.The Aleutian-Alaska subduction zone has a convergence rate of approximately 50 mm/yr,with a trench length reaching nearly 2800 km.Such a long subduction zone has led to intensive continental deformation and numerous strong earthquakes in southern and central Alaska,while northern Alaska is relatively inactive.The sharp contrast makes Alaska a favorable locale to investigate the impact of subduction on mantle dynamics.Moreover,the uniqueness of this subduction zone,including the unusual subducting type,varying slab geometry,and atypical magmatic activity and composition,has intrigued the curiosity of many geoscientists.To identify different sources of seismic anisotropy beneath the Alaska region and probe the influence of a geometrically varying subducting slab on mantle dynamics,extensive SWS analyses have been conducted in the past decades.However,the insufficient station and azimuthal coverage,especially in early studies,not only led to some conflicting results but also strongly limited the in-depth investigation of layered anisotropy and the estimation of anisotropy depth.With the completion of the Transportable Array project in Alaska,recent studies have revealed more detailed mantle structures and characteristics based on the dense station coverage and newly collected massive seismic data.In this study,we review significant regional-and continental-scale SWS studies in the Alaska region and conclude the mantle flow fields therein,to understand how a geometrically varying subducting slab alters the regional mantle dynamics.The summarized mantle flow mechanisms are believed to be conducive to the understanding of seismic anisotropy patterns in other subduction zones with a complicated tectonic setting.展开更多
How the state of living muscles modulates the features of nonlinear elastic waves generated by external dynamic loads remains unclear because of the challenge of directly observing and modeling nonlinear elastic waves...How the state of living muscles modulates the features of nonlinear elastic waves generated by external dynamic loads remains unclear because of the challenge of directly observing and modeling nonlinear elastic waves in skeletal muscles in vivo,considering their active deformation behavior.Here,this important issue is addressed by combining experiments performed with an ultrafast ultrasound imaging system to track nonlinear shear waves(shear shock waves)in muscles in vivo and finite element analysis relying on a physically motivated constitutive model to study the effect of muscle activation level.Skeletal muscle was loaded with a deep muscle stimulator to generate shear shock waves(SSWs).The particle velocities,second and third harmonics,and group velocities of the SSWs in living muscles under both passive and active states were measured in vivo.Our experimental results reveal,for the first time,that muscle states have a pronounced effect on wave features;a low level of activation may facilitate the occurrence of both the second and third harmonics,whereas a high level of activation may inhibit the third harmonic.Finite element analysis was further carried out to quantitatively explore the effect of active muscle deformation behavior on the generation and propagation of SSWs.The simulation results at different muscle activation levels confirmed the experimental findings.The ability to reveal the effects of muscle state on the features of SSWs may be helpful in elucidating the unique dynamic deformation mechanism of living skeletal muscles,quantitatively characterizing diverse shock wave-based therapy instruments,and guiding the design of muscle-mimicking soft materials.展开更多
基金Supported by Guangdong Medical Science and Technology Research Fund Project,No.A2024475.
文摘This study explores the significance of using two-dimensional shear wave elastography(2D-SWE)to assess liver stiffness(LS)and spleen area(SPA)for predicting post-hepatectomy liver failure(PHLF).By providing a non-invasive method to measure LS,which correlates with the degree of liver fibrosis,and SPA,an indicator of portal hypertension,2D-SWE offers a comprehensive evaluation of a patient’s hepatic status.These advancements are particularly crucial in hepatic surgery,where accurate preoperative assessments are essential for optimizing surgical outcomes and minimizing complications.This letter highlights the prac-tical implications of integrating 2D-SWE into clinical practice,emphasizing its potential to improve patient safety and surgical precision by enhancing the ability to predict PHLF and tailor surgical approaches accordingly.
基金Supported by the Natural Science Foundation of Shanghai,No.22ZR1458200Medical Ph.D Innovative Talent Base Project of Changning District,No.RCJD2021B09+1 种基金Key Specialty of Changning District,No.20231004Shanghai Changning Maternity and Infant Health Hospital Start-Up Project,No.2020Y-14.
文摘BACKGROUND Thyroid dysfunction during pregnancy is an important disease affecting the health of mothers and children.Two-dimensional(2D)shear wave elastography(SWE)is the newest ultrasonic elastography technology and its value in differentiating benign and malignant thyroid nodules has been widely recognized.However,the value of 2D SWE in evaluating and predicting thyroid function is unclear.AIM To explore prospectively the value of 2D SWE quantitative analysis for the evaluation of thyroid function in the first trimester.METHODS We included outpatients of reproductive age in the Department of Gynecology in Shanghai Changning Maternity and Infant Health Hospital between March 2023 and March 2024 who had conventional ultrasound examination and 2D SWE of the thyroid.They also underwent transvaginal ultrasound examination to confirm early intrauterine pregnancy and serum thyroid stimulating hormone(TSH)level was measured.The patients were divided into pregnant with normal TSH,pregnant with abnormal TSH,and nonpregnant with normal TSH.Conventional ultrasound and 2D SWE results were compared among the three groups.RESULTS A total of 108 patients were included in the study;57 in the pregnant with normal TSH group,18 in the pregnant with abnormal TSH group and 33 were in the nonpregnant with normal TSH group.Thyroid size,thyroid echotexture,2D SWE quantitative parameters including mean elasticity in the region of interest and maximal elasticity in the region of interest showed no significant differences among the three groups(P>0.05).CONCLUSION Conventional ultrasound and 2D SWE features could not reflect the level of serum TSH.
基金Supported by Natural Science Foundation of Shanghai of China,No.19ZR1441500,No.22ZR1458200Science Research Foundation of Shanghai Municipal Health Commission,No.202140378Key Program of Science and Technology Commission Foundation of Changning,Shanghai,China,No.CNKW2020Z04.
文摘BACKGROUND The clinical management and prognosis differ between benign and malignant solid focal liver lesions(FLLs),as well as among different pathological types of malignant FLLs.Accurate diagnosis of the possible types of solid FLLs is important.Our previous study confirmed the value of shear wave elastography(SWE)using maximal elasticity(Emax)as the parameter in the differential diagnosis between benign and malignant FLLs.However,the value of SWE in the differential diagnosis among different pathological types of malignant FLLs has not been proved.AIM To explore the value of two-dimensional SWE(2D-SWE)using Emax in the differential diagnosis of FLLs,especially among different pathological types of malignant FLLs.METHODS All the patients enrolled in this study were diagnosed as benign,malignant or undetermined FLLs by conventional ultrasound.Emax of FLLs and the periphery of FLLs was measured using 2D-SWE and compared between benign and malignant FLLs or among different pathological types of malignant FLLs.RESULTS The study included 32 benign FLLs in 31 patients and 100 malignant FLLs in 96 patients,including 16 cholangiocellular carcinomas(CCCs),72 hepatocellular carcinomas(HCCs)and 12 liver metastases.Thirty-five FLLs were diagnosed as undetermined by conventional ultrasound.There were significant differences between Emax of malignant(2.21±0.57 m/s)and benign(1.59±0.37 m/s)FLLs(P=0.000),and between Emax of the periphery of malignant(1.52±0.39 m/s)and benign(1.36±0.44 m/s)FLLs(P=0.040).Emax of liver metastases(2.73±0.99 m/s)was significantly higher than that of CCCs(2.14±0.34 m/s)and HCCs(2.14±0.46 m/s)(P=0.002).The sensitivity,specificity and accuracy were 71.00%,84.38%and 74.24%respectively,using Emax>1.905 m/s(AUC 0.843)to diagnose as malignant and 23 of 35(65.74%)FLLs with undetermined diagnosis by conventional ultrasound were diagnosed correctly.CONCLUSION Malignant FLLs were stiffer than benign ones and liver metastases were stiffer than primary liver carcinomas.2D-SWE with Emax was a useful complement to conventional ultrasound for the differential diagnosis of FLLs.
文摘Two-dimensional shear wave elastography(2D-SWE)is used in the clinical setting for observation of the liver.Unfortunately,a wide spectrum of artifactual images are frequently encountered in 2D-SWE,the precise mechanisms of which remain incompletely understood.This review was designed to present many of the artifactual images seen in 2D-SWE of the liver and to analyze them by computer simulation models that support clinical observations.Our computer simulations yielded the following suggestions:(1)When performing 2D-SWE in patients with chronic hepatic disease,especially liver cirrhosis,it is recommended to measure shear wave values through the least irregular hepatic surface;(2)The most useful 2D-SWE in patients with focal lesion will detect lesions that are poorly visible on B-mode ultrasound and will differentiate true tumors from pseudo-tumors(e.g.,irregular fatty change);and(3)Measurement of shear wave values in the area posterior to a focal lesion must be avoided.
基金National Natural Science Foundation of China,No.81372626Key Research and Development Project of Science and Technology Department of Zhejiang,China,No.2015C03053Zhejiang Provincial Program for the Cultivation of High-level Innovative Health Talents.
文摘BACKGROUND Post-hepatectomy liver failure(PHLF)increases morbidity and mortality after liver resection for patients with advanced liver fibrosis and cirrhosis.Preoperative liver stiffness using two-dimensional shear wave elastography(2D-SWE)is widely used to evaluate the degree of fibrosis.However,the 2D-SWE results were not accurate.A durometer measures hardness by quantifying the ability of a material to locally resist the intrusion of hard objects into its surface.However,the durometer score can only be obtained during surgery.To measure correlations among 2D-SWE,palpation by surgeons,and durometermeasured objective liver hardness and to construct a liver hardness regression model.METHODS We enrolled 74 hepatectomy patients with liver hardness in a derivation cohort.Tactile-based liver hardness scores(0-100)were determined through palpation of the liver tissue by surgeons.Additionally,liver hardness was measured using a durometer.Correlation coefficients for durometer-measured hardness and preoperative parameters were calculated.Multiple linear regression models were constructed to select the best predictive durometer scale.Receiver operating characteristic(ROC)curves and univariate and multivariate analyses were used to calculate the best model’s prediction of PHLF and risk factors for PHLF,respectively.A separate validation cohort(n=162)was used to evaluate the model.RESULTS The stiffness measured using 2D-SWE and palpation scale had good linear correlation with durometer-measured hardness(Pearson rank correlation coefficient 0.704 and 0.729,respectively,P<0.001).The best model for the durometer scale(hardness scale model)was based on stiffness,hepatitis B virus surface antigen,and albumin level and had an R2 value of 0.580.The area under the ROC for the durometer and hardness scale for PHLF prediction were 0.807(P=0.002)and 0.785(P=0.005),respectively.The optimal cutoff value of the durometer and hardness scale was 27.38(sensitivity=0.900,specificity=0.660)and 27.87(sensitivity=0.700,specificity=0.787),respectively.Patients with a hardness scale score of>27.87 were at a significantly higher risk of PHLF with hazard ratios of 7.835(P=0.015).The model’s PHLF predictive ability was confirmed in the validation cohort.CONCLUSION Liver stiffness assessed by 2D-SWE and palpation correlated well with durometer hardness values.The multiple linear regression model predicted durometer hardness values and PHLF.
文摘Objective:To explore the feasibility of two-dimensional shear wave elastography in evaluating calf skeletal muscle stiffness in diabetic nephropathy patients with medial tibial stress syndrome.Methods:A total of 48 diabetic nephropathy patients with medial tibial stress syndrome from January 2020 to December 2022 were included as the study group,and 48 patients with diabetic nephropathy during the same period were included as the control group.Both groups were detected by two-dimensional shear wave elastography with ultrasonic equipment,and Young‘s modulus of the tibialis anterior muscle,tibialis posterior muscle,and gastrocnemius muscle were observed and analyzed in the two groups.Results:The Young‘s modulus values of tibialis anterior muscle,tibialis posterior muscle,and gastrocnemius muscle in the study group were significantly lower than those in the control group(P<0.05).Conclusion:Two-dimensional shear wave elastography is feasible for the evaluation of calf skeletal muscle stiffness in diabetic nephropathy patients with medial tibial stress syndrome,and has high accuracy and repeatability.This technique can be used to diagnose,treat and monitor muscle lesions in patients with diabetic nephropathy,and can also be used to assess muscle fatigue and exercise capacity,which has broad application prospects.
文摘Two-dimensional shear wave elastography(2D-SWE) is a rapid, simple and novel noninvasive method that has been proposed for assessing hepatic fibrosis in patients with chronic liver diseases(CLDs) based on measurements of liver stiffness. 2 D-SWE can be performed easily at the bedside or in an outpatient clinic and yields immediate results with good reproducibility. Furthermore, 2 D-SWE was an efficient method for evaluating liver fibrosis in small to moderately sized clinical trials. However, the quality criteria for the staging of liver fibrosis are not yet well defined. Liver fibrosis is the main pathological basis of liver stiffness and a key step in the progression from CLD to cirrhosis; thus, the management of CLD largely depends on the extent and progression of liver fibrosis. 2 D-SWE appears to be an excellent tool for the early detection of cirrhosis and may have prognostic value in this context. Because 2 D-SWE has high patient acceptance, it could be useful for monitoring fibrosis progression and regression in individual cases. However, multicenter data are needed to support its use. This study reviews the current status and future perspectives of 2 D-SWE for assessments of liver fibrosis and discusses the technical advantages and limitations that impact its effective and rational clinical use.
文摘Liver biopsy is the gold standard for evaluating the degree of liver fibrosis in patients with chronic liver disease. However, due to the many limitations of liver biopsy, there has been much interest in the use of noninvasive techniques for this purpose. Among these techniques real-time two-dimensional shear wave elastography(2D-SWE) has the advantage of measuring tissue elasticity with the guidance of B-mode images. Recently, many studies have been conducted on the application of 2D-SWE in patients with various liver diseases, and their validity has been confirmed. Here, we briefly discuss the role of 2D-SWE in patients with chronic liver diseases, particularly aspects of the examination techniques and clinical applications.
基金the National Natural Science Foundation of China(81900594)Clinical Research Plan of Shanghai Hospital Development Center(Grant 16CR3109B)Shanghai Youth Sci&Tech Talent Jump starting Program(18YF1412700).
文摘Background:Liver fibrosis is a common pathological change caused by a variety of etiologies.Early diagnosis and timely treatment can reverse or delay disease progression and improve the prognosis.This study aimed to assess the potential utility of two-dimensional shear wave elastography and texture analysis in dynamic monitoring of the progression of liver fibrosis in rat model.Methods:Twenty rats were divided into control group(n=4)and experimental groups(n=4 per group)with carbon tetrachloride administration for 2,3,4,and 6 weeks.The liver stiffness measurement was performed by two-dimensional shear wave elastography,while the optimal texture analysis subsets to distinguish fibrosis stage were generated by MaZda.The results of elastography and texture analysis were validated through comparing with histopathology.Results:Liver stiffness measurement was 6.09±0.31 kPa in the control group and 7.10±0.41 kPa,7.80±0.93 kPa,8.64±0.93 kPa,9.91±1.13 kPa in the carbon tetrachloride induced groups for 2,3,4,6 weeks,respectively(P<0.05).By texture analysis,histogram and co-occurrence matrix had the most frequency texture parameters in staging liver fibrosis.Receiver operating characteristic curve of liver elasticity showed that the sensitivity and specificity were 95.0%and 92.5%to discriminate liver fibrosis and non-fibrosis,respectively.In texture analysis,five optimal parameters were selected to classify liver fibrosis and non-fibrosis.Conclusions:Two-dimensional shear wave elastography showed potential applications for noninvasive monitoring of the progression of hepatic fibrosis,even in mild fibrosis.Texture analysis can further extract and quantify the texture features in ultrasonic image,which was a supplementary to further visual information and acquired high diagnostic accuracy for severe fibrosis.
文摘BACKGROUND Few systematic comparative studies of the different methods of physical elastography of the spleen are currently available.AIM To compare point shear wave and two-dimensional elastography of the spleen considering the anatomical location(upper,hilar,and lower pole).METHODS As part of a prospective clinical study,healthy volunteers were examined for splenic elasticity using four different ultrasound devices between May 2015 and April 2017.The devices used for point shear wave elastography were from Siemens(S 3000)and Philips(Epiq 7),and those used for two-dimensional shear wave elastography were from GE(Logiq E9)and Toshiba(Aplio 500).In addition,two different software versions(5.0 and 6.0)were evaluated for the Toshiba ultrasound device(Aplio 500).The study consisted of three arms:A,B,and C.RESULTS In study arm A,200 subjects were evaluated(78 males and 122 females,mean age 27.9±8.1 years).In study arm B,113 subjects were evaluated(38 men and 75 women,mean age 26.0±6.3 years).In study arm C,44 subjects were enrolled.A significant correlation of the shear wave velocities at the upper third of the spleen(r=0.33088,P<0.0001)was demonstrated only for the Philips Epiq 7 device compared to the Siemens Acuson S 3000.In comparisons of the other ultrasound devices(GE,Siemens,Toshiba),no comparable results could be obtained for any anatomical position of the spleen.The influencing factors age,gender,and body mass index did not show a clear correlation with the measured shear wave velocities.CONCLUSION The absolute values of the shear wave elastography measurements of the spleen and the two different elastography methods are not comparable between different manufacturers or models.
基金supported by Scientific Research and Technology Development Project of CNPC(2024ZG38,2024ZG42)the CNPC Innovation Fund(2022DQ02-0307).
文摘Fractures play a crucial role in various fields such as hydrocarbon exploration,groundwater resources management,and earthquake research.The determination of fracture location and the estimation of parameters such as fracture length and dip angle are the focus of geophysical work.In borehole observation system,the short distance between fractures and detectors leads to weak attenuation of elastic wave energy,and high-frequency source makes it easier to identify small-scale fractures.Compared to traditional monopole logging methods,dipole logging method has advantage of exciting pure shear waves sensitive to fractures,so its application is becoming increasingly widespread.However,since the reflected shear waves and scattered shear waves of fractures correspond to different fracture properties,how to distinguish and analyze these two kinds of waves is crucial for accurately characterizing the fracture parameters.To address this issue,numerical simulation of wave responses by a single fracture near a borehole in rock formation is performed,and the generation mechanism and characteristics of shear waves scattered by fractures are investigated.It is found that when the dip angle of the fracture surpasses a critical threshold,the S-wave will propagate to both endpoints of the fracture and generate scattered S-waves,resulting in two distinct scattered wave packets on the received waveform.When the polarization direction of the acoustic source is parallel to the strike of the fracture,the scattered SH-waves always have larger amplitude than the scattered SV-waves regardless of changing the fracture dip angle.Unlike SV-waves,the SH-waves scattered by the fracture do not have any mode conversion.Additionally,propagation of S-waves to a short length fracture can induce dipole mode vibration of the fracture within a wide frequency range.The phenomena of shear waves reflected and scattered by the fracture are further illustrated and verified by two field examples,thus showing the potential of scattered waves for fracture evaluation and characterization with borehole observation system.
基金Supported by the National Natural Science Foundation of China Youth Training Project,No.2021GZR003and Medical-engineering Interdisciplinary Research Youth Training Project,No.2022YGJC001.
文摘BACKGROUND Integrating conventional ultrasound features with 2D shear wave elastography(2D-SWE)can potentially enhance preoperative hepatocellular carcinoma(HCC)predictions.AIM To develop a 2D-SWE-based predictive model for preoperative identification of HCC.METHODS A retrospective analysis of 884 patients who underwent liver resection and pathology evaluation from February 2021 to August 2023 was conducted at the Oriental Hepatobiliary Surgery Hospital.The patients were divided into the modeling group(n=720)and the control group(n=164).The study included conventional ultrasound,2D-SWE,and preoperative laboratory tests.Multiple logistic regression was used to identify independent predictive factors for RESULTS In the modeling group analysis,maximal elasticity(Emax)of tumors and their peripheries,platelet count,cirrhosis,and blood flow were independent risk indicators for malignancies.These factors yielded an area under the curve of 0.77(95%confidence interval:0.73-0.81)with 84%sensitivity and 61%specificity.The model demonstrated good calibration in both the construction and validation cohorts,as shown by the calibration graph and Hosmer-Lemeshow test(P=0.683 and P=0.658,respectively).Additionally,the mean elasticity(Emean)of the tumor periphery was identified as a risk factor for microvascular invasion(MVI)in malignant liver tumors(P=0.003).Patients receiving antiviral treatment differed significantly in platelet count(P=0.002),Emax of tumors(P=0.033),Emean of tumors(P=0.042),Emax at tumor periphery(P<0.001),and Emean at tumor periphery(P=0.003).CONCLUSION 2D-SWE’s hardness value serves as a valuable marker for enhancing the preoperative diagnosis of malignant liver lesions,correlating significantly with MVI and antiviral treatment efficacy.
基金Supported by Sichuan Orthopaedic Hospital Research Project,No.2019MS02.
文摘BACKGROUND Real-time shear wave elastography(SWE)is a non-invasive imaging technique used to measure tissue stiffness by generating and tracking shear waves in real time.This advanced ultrasound-based method provides quantitative information regarding tissue elasticity,offering valuable insights into the mechanical properties of biological tissues.However,the application of real-time SWE in the musculoskeletal system and sports medicine has not been extensively studied.AIM To explore the practical value of real-time SWE for assessing Achilles tendon hardness in older adults.METHODS A total of 60 participants were enrolled in the present study,and differences in the elastic moduli of the bilateral Achilles tendons were compared among the following categories:(1)Age:55-60,60-65,and 65-70-years-old;(2)Sex:Male and female;(3)Laterality:Left and right sides;(4)Tendon state:Relaxed and tense state;and(5)Tendon segment:Proximal,middle,and distal.RESULTS There were no significant differences in the elastic moduli of the bilateral Achilles tendons when comparing by age or sex(P>0.05).There were,however,significant differences when comparing by tendon side,state,or segment(P<0.05).CONCLUSION Real-time SWE plays a significant role compared to other examination methods in the evaluation of Achilles tendon hardness in older adults.
基金supported by the National Key R&D Program of China(Grant No.2022YFC2402400)the National Natural Science Foundation of China(Grant No.62275062)and Guangdong Provincial Key Laboratory of Biomedical Optical Imaging Technology(Grant No.2020B121201010-4).
文摘Elastography can be used as a diagnostic method for quantitative characterization of tissue hardness information and thus,differential changes in pathophysiological states of tissues.In this study,we propose a new method for shear wave elastography(SWE)based on laser-excited shear wave,called photoacoustic shear wave elastography(PASWE),which combines photoacoustic(PA)technology with ultrafast ultrasound imaging.By using a focused laser to excite shear waves and ultrafast ultrasonic imaging for detection,high-frequency excitation of shear waves and noncontact elastic imaging can be realized.The laser can stimulate the tissue with the light absorption characteristic to produce the thermal expansion,thus producing the shear wave.The frequency of shear wave induced by laser is higher and the frequency band is wider.By tracking the propagation of shear wave,Young’s modulus of tissue is reconstructed in the whole shear wave propagation region to further evaluate the elastic information of tissue.The feasibility of the method is verified by experiments.Compared with the experimental results of supersonic shear imaging(SSI),it is proved that the method can be used for quantitative elastic imaging of the phantoms.In addition,compared with the SSI method,this method can realize the noncontact excitation of the shear wave,and the frequency of the shear wave excited by the laser is higher than that of the acoustic radiation force(ARF),so the spatial resolution is higher.Compared to the traditional PA elastic imaging method,this method can obtain a larger imaging depth under the premise of ensuring the imaging resolution,and it has potential application value in the clinical diagnosis of diseases requiring noncontact quantitative elasticity.
文摘Liquefaction assessment based on strain energy is significantly superior to conventional stress-based methods.The main purpose of the present study is to investigate the correlation between shear wave velocity and strain energy capacity of silty sands.The dissipated energy until liquefaction occurs was calculated by analyzing the results of three series of comprehensive cyclic direct simple shear and triaxial tests on Ottawa F65,Nevada,and Firoozkuh sands with varying silt content by weight and relative densities.Additionally,the shear wave velocity of each series was obtained using bender element or resonant column tests.Consequently,for the first time,a liquefaction triggering criterion,relating to effective overburden normalized liquefaction capacity energy(WL=s’c)to effective overburden stresscorrected shear wave velocity(eVs1)has been introduced.The accuracy of the proposed criteria was evaluated using in situ data.The results confirm the ability of shear wave velocity as a distinguishing parameter for separating liquefied and non-liquefied soils when it is calculated against liquefaction capacity energy(WL=s’c).However,the proposed WL=s’c-Vs1 curve,similar to previously proposed cyclic resistance ratio(CRR)-Vs1 relationships,should be used conservatively for fields vulnerable to liquefaction-induced lateral spreading.
基金supported by the Qingdao Natural Science Foundation(No.23-2-1-54-zyyd-jch)the National Natural Science Foundation of China(Nos.42206233 and 42206231)+2 种基金the National Key Research and Development Pro-gram of China(No.2022YFC2806405)the Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University(No.KLE-TJGE-G2202)the Laoshan Laboratory(No.LSKJ202203506)。
文摘The strength parameters of hydrate-bearing sediments(HBS)are vital to geological risk assessment and control during drilling and production operations.However,current publications mainly focus on the laboratory evaluation of strength parameters through triaxial compression,generating results intrinsically deviating from those obtained through petrophysical modeling.In this study,we developed an integrated apparatus that can simultaneously measure wave velocity and the mechanical behaviors of HBS under triaxial compression conditions.A series of experiments were conducted to analyze correlations between wave velocities and strength parameters.Results reveal that the P-and S-wave velocities considerably increase with hydrate saturation and are affected by effective confining pressure.Failure strength and elastic modulus are correlated with P-wave velocity.Finally,semi-empirical models are developed to predict strength parameters based on P-wave velocity and extended to establish longitudinal profiles for strength parameters of hydrate reservoirs in the Nankai Trough.This study offers insights into the acoustic properties of HBS under stress states for the prediction of mechanical parameters during natural gas hydrate development.
基金The project supported by National Natural Science Foundation of China under Grant No.10771196the Natural Science Foundation of Zhejiang Province under Grant No.Y605044
文摘Two new exact, rational and periodic wave solutions are derived for the two-dimensional Boussinesq equation. For the first solution it is obtained by performing an appropriate limiting procedure on the soliton solutions obtained by Hirota bilinear method. The second one in terms of Riemann theta function is explicitly presented by virtue of Hirota bilinear method and its asymptotic property is also analyzed in detail. Moreover, it is of interest to note that classical soliton solutions can be reduced from the periodic wave solutions.
文摘The horizontal-to-vertical spectral ratio(HVSR)method has been used to characterize site-effect parameters that are indispensable in seismic hazard and risk-reduction studies in urban areas and rapid land-use planning.This method is widely used because it is the cheapest and simplest geophysical method for the acquisition and processing stages.In subsequent developments,the HVSR method has been widely used to determine elastic rock parameters,particularly shear wave velocity(v_(S)),through the HVSR curve inversion process.Furthermore,the v_(S)structural model can be used to delineate the presence of complex geological structures,particularly faults and sedimentary basins.Bandar Lampung is a city in Lampung Province with many fault structures and groundwater basins to the south.There are 83 HVSR measurement points around Bandar Lampung for delineating the presence of fault structures and groundwater basins.We produced the HVSR curve from the measurement results and then performed an inversion process using the particle swarm optimization algorithm to obtain v_(S)for the depth profile.Subsequently,from this profile,we produced a two-dimensional(2D)lateral and vertical model.The mean v_(S)value was calculated from all the measurement points,and we found stiff soil layers reaching depths of approximately 5 m,with a value of v_(S)<330 m/s.A bedrock layer with a velocity exceeding 1250 m/s was visible at a depth of 100 m.Based on the 2D model,the v_(S)structure shows that the city of Bandar Lampung is divided into two zones,with a NW-SE boundary.The north-middle-eastern part of the city consists of harder rocks.This harder rock is characterized by extremely high v_(S)values,starting from a depth of 50 m.In contrast,the south-middle-west exhibits a low-moderate v_(S)anomaly associated with groundwater basins SW of the city.From the 2D v_(S)structural model,fault structures can be found along the city,characterized by a contrast of v_(S)values from low to medium and from medium to high.
基金supported by the Outstanding Youth Project of Natural Science Foundation of Heilongjiang(YQ2023D006).
文摘Shear wave splitting(SWS)is regarded as the most effective geophysical method to delineate mantle flow fields by detecting seismic azimuthal anisotropy in the earth's upper mantle,especially in tectonically active regions such as subduction zones.The Aleutian-Alaska subduction zone has a convergence rate of approximately 50 mm/yr,with a trench length reaching nearly 2800 km.Such a long subduction zone has led to intensive continental deformation and numerous strong earthquakes in southern and central Alaska,while northern Alaska is relatively inactive.The sharp contrast makes Alaska a favorable locale to investigate the impact of subduction on mantle dynamics.Moreover,the uniqueness of this subduction zone,including the unusual subducting type,varying slab geometry,and atypical magmatic activity and composition,has intrigued the curiosity of many geoscientists.To identify different sources of seismic anisotropy beneath the Alaska region and probe the influence of a geometrically varying subducting slab on mantle dynamics,extensive SWS analyses have been conducted in the past decades.However,the insufficient station and azimuthal coverage,especially in early studies,not only led to some conflicting results but also strongly limited the in-depth investigation of layered anisotropy and the estimation of anisotropy depth.With the completion of the Transportable Array project in Alaska,recent studies have revealed more detailed mantle structures and characteristics based on the dense station coverage and newly collected massive seismic data.In this study,we review significant regional-and continental-scale SWS studies in the Alaska region and conclude the mantle flow fields therein,to understand how a geometrically varying subducting slab alters the regional mantle dynamics.The summarized mantle flow mechanisms are believed to be conducive to the understanding of seismic anisotropy patterns in other subduction zones with a complicated tectonic setting.
基金supported by the National Students Training Program for Innovation(Grant No.202210007029)。
文摘How the state of living muscles modulates the features of nonlinear elastic waves generated by external dynamic loads remains unclear because of the challenge of directly observing and modeling nonlinear elastic waves in skeletal muscles in vivo,considering their active deformation behavior.Here,this important issue is addressed by combining experiments performed with an ultrafast ultrasound imaging system to track nonlinear shear waves(shear shock waves)in muscles in vivo and finite element analysis relying on a physically motivated constitutive model to study the effect of muscle activation level.Skeletal muscle was loaded with a deep muscle stimulator to generate shear shock waves(SSWs).The particle velocities,second and third harmonics,and group velocities of the SSWs in living muscles under both passive and active states were measured in vivo.Our experimental results reveal,for the first time,that muscle states have a pronounced effect on wave features;a low level of activation may facilitate the occurrence of both the second and third harmonics,whereas a high level of activation may inhibit the third harmonic.Finite element analysis was further carried out to quantitatively explore the effect of active muscle deformation behavior on the generation and propagation of SSWs.The simulation results at different muscle activation levels confirmed the experimental findings.The ability to reveal the effects of muscle state on the features of SSWs may be helpful in elucidating the unique dynamic deformation mechanism of living skeletal muscles,quantitatively characterizing diverse shock wave-based therapy instruments,and guiding the design of muscle-mimicking soft materials.
