Microwave-induced thermoacoustic elastic imaging:A simulation study

Microwave-induced thermoacoustic imaging(MTI)has the advantages of high resolution,high contrast,non-ionization,and non-invasive.Recently,MTI was used in the¯eld of breast cancer screening.In this paper,based on the¯nite element method(FEM)and COMSOL Multiphysics software,a three-dimensional breast cancer model suitable for exploring the MTI process is proposed to investigate the in°uence of Young's modulus(YM)of breast cancer tissue on MTI.It is found that the process of electromagnetic heating and initial pressure generation of the entire breast tissue is earlier in time than the thermal expansion process.Besides,compared with normal breast tissue,tumor tissue has a greater temperature rise,displacement,and pressure rise.In particular,YM of the tumor is related to the speed of thermal expansion.In particular,the larger the YM of the tumor is,the higher the heating and contraction frequency is,and the greater the maximum pressure is.Di®erent Young's moduli correspond to di®erent thermoacoustic signal spectra.In MTI,this study can be used to judge di®erent degrees of breast cancer based on elastic imaging.In addition,this study is helpful in exploring the possibility of microwave-induced thermoacoustic elastic imaging(MTAE).

A Modified Monte Carlo Model of Speckle Tracking of Shear Wave Induced by Acoustic Radiation Force for Acousto-Optic Elasticity Imaging

A modified Monte Carlo model of speckle tracking of shear wave propagation in scattering media is proposed. The established Monte Carlo model mainly concerns the variations of optical electric field and speckle. The two- dimensional intensity distribution and the time evolution of speckles in different probe locations are obtained. The fluctuation of speckle intensity tracks the acoustic-radiation-force shear wave propagation, and especially the reduction of speckle intensity implies attenuation of shear wave. Then, the shear wave velocity is estimated quantitatively on the basis of the time-to-peak algorithm and linear regression processing. The results reveal that a smaller sampling interval yields higher estimation precision and the shear wave velocity is estimated more efficiently by using speckle intensity difference than by using speckle contrast difference according to the estimation error. Hence, the shear wave velocity is estimated to be 2.25 m/s with relatively high accuracy for the estimation error reaches the minimum （0.071）.

Advances in the Diagnosis of Breast Tumor by Using Imaging Technology

Breast tumor is the most common tumor in the world. The most important method to reduce the mortality due to breast tumor is diagnosed and found as early as possible. Imaging technology is one of the most important means to help doctors diagnose tumor early. This paper first simply introduces the common imaging technology. Then the mechanism and application of the ultrasonic elastic imaging technology in the diagnosis of breast tumor are summarized and discussed detailly. The methods for image treatment are introduced also. At last the development trend is analyzed. It is shown that the ultrasonic imaging technology is the most convenient and the cheapest relative to other imaging technologies such as nuclear magnetic imaging (NMI) and computer tomography (CT). Especially the ultrasonic elastic imaging technology can provide not only imaging information but also mechanism parameters, which helps to improve the accuracy of diagnosis obviously. Therefore, the ultrasonic elastic imaging technology is worthy of being studied further. More effective image analysis method is required.

Quantitative Characterization and Elastic Properties of Interfacial Transition Zone around Coarse Aggregate in Concrete

Backscattered electron images（BSE） obtained by scanning electron microscope was used to quantitatively characterize the microstructure of interfacial transition zone（ITZ） in concrete. Influences of aggregate size（5, 10, 20, and 30 mm）, water to cement ratio（0.23, 0.35 and 0.53） and curing time（from 3d to 90d） on the microstructure of interfacial transition zone between coarse aggregate and bulk cement matrix were investigated. The volume percentage of detectable porosity and unhydrated cement in ITZ was quantitatively analyzed and compared with that in the matrix of various concretes. Nanoindentation technology was applied to obtain the elastic properties of ITZ and matrix, and the elastic modulus of concrete was then calculated based on the Lu ＆ Torquato model and self-consistence scheme by using the ITZ thickness and elastic modulus obtained from this investigation. The experimental results demonstrated that the microstructure and thickness of ITZ in concrete vary with a variety of factors, like aggregate size, water to cement ratio and curing time. The relative low elastic properties of ITZ should be paid attention to, especially for early age concrete.

E-Cervix imaging displaying cervical elasticity characteristics of healthy adult nulliparous women at different age groups and different menstrual cycle stages

Objective To observe the cervical elasticity of healthy adult nulliparous women at different age groups and different stages of menstrual cycle with E-Cervix imaging technology.Methods A total of 218 healthy adult nulliparous women who underwent transvaginal ultrasound examination for routine physical examination were retrospectively enrolled,including 103 in follicular phase,78 in ovulation phase and 37 in luteal phase.Cervical canal length(CL)and E-Cervix elasticity parameters were compared among different age groups and different stages of menstrual cycle,including elasticity contrast index(ECI),hardness ratio(HR),cervical internal and external orifice strain values(IOS and EOS)and IOS/EOS ratio.Results No significant difference of CL nor cervical elasticity parameters was detected among healthy adult nulliparous women at different age groups(all P>0.05).There were significant differences of ECI,HR and IOS among different menstrual cycle stages(all P<0.05),among which women in follicular phase had higher ECI and IOS but lower HR than those in luteal phase(all P<0.05).Conclusion No significant difference of cervical elasticity existed among healthy adult nulliparous women at different age groups.Meanwhile,cervical elasticity of healthy adult nulliparous women changed during menstrual cycle,in follicular phase had higher ECI and IOS but lower HR than in luteal phase.

Quantitatively evaluation on pelvic floor dysfunction by virtual touch tissue imaging quantification shear wave elastography

Objective:To investigate the value of(VTIQ)shear wave elastography in the diagnosis of pelvic floor dysfunction.Methods:20 patients with pelvic floor dysfunction and 40 healthy volunteers were enrolled in and devided into the pelvic floor dysfunction(PFD)group and the control group.20 cases in the normal non-fertile(NNF)group and the normal fertile(NF)group respectively were including in the control group.The Young's modulus of puborectalis(PR)in three groups was measured by virtual touch tissue imaging quantification(VTIQ)at different states.The Young's modulus of PR and their differences in the three groups and between groups were compared and calculated.Receiver-operating characteristic curve(ROC)analyses were performed to assess the diagnostic value of VTIQ,and the area under the curve(AUC)was compared.Results:Young's modulus of PR at resting-state,maximun rectal state and Vasalva state in NNF group and NF group were statistical significance(all P<0.05).Young's modulus of maximun rectal state was higher than that of resting-state and Vasalva state in PFD group(P<0.05).There was no significant difference in Young's modulus between the resting-state and Vasalva state in the PFD group(P>0.05).Difference of PR Young's modulus between resting status and maximun rectal state and that between resting status and Vasalva state were of statistical significance among the three groups(all P<0.05).ROC curves analyses indicated that the AUC,cut-off value,sensitivity,specificity and Youden index of the difference between the Young's modulus of resting status and maximun rectal state measured by VTIQ in control group and PFD group were 0.788,35.45kPa,91.67%,57.14%,0.488,espectively.The AUC,cut-off value,sensitivity,specificity and Youden index of the difference between the Young's modulus of resting status and Vasalva state measured by VTIQ in control group and PFD group were 0.799,14.00kPa,63.89%,85.71%,0.496,respectively.There was no significant difference in AUC between the two groups(Z=0.130,P>0.05).Conclusion:VTIQ technology is an effective method to quantitatively assess the biomechanical properties of PR.The effect of labor on the puborectalis muscle was not significant.The increase of Young's modulus of passive stretching in vasalva state was not significant in patients with pelvic floor dysfunction.The difference between resting status and maximun rectal state and difference between resting status and Vasalva state is more advantageous to the diagnosis of pelvic floor dysfunction disorder.

Increased liver stiffness in alcoholic liver disease:Differentiating fibrosis from steatohepatitis

AIM:To test if inflammation also interferes with liver stiffness (LS) assessment in alcoholic liver disease (ALD) and to provide a clinical algorithm for reliable fibrosis assessment in ALD by FibroScan (FS).METHODS:We first performed sequential LS analysis before and after normalization of serum transaminases in a learning cohort of 50 patients with ALD admitted for alcohol detoxification. LS decreased in almost all patients within a mean observation interval of 5.3 d. Six patients (12%) would have been misdiagnosed with F3and F4 fibrosis but LS decreased below critical cut-off values of 8 and 12.5 kPa after normalization of trans-aminases. RESULTS:Of the serum transaminases,the decrease in LS correlated best with the decrease in glutamic oxaloacetic transaminase (GOT). No significant chang-es in LS were observed below GOT levels of 100 U/L. After establishing the association between LS and GOT levels,we applied the rule of GOT < 100 U/L for reliable LS assessment in a second validation cohort of 101 patients with histologically confi rmed ALD. By ex-cluding those patients with GOT > 100 U/L at the time of LS assessment from this cohort,the area under the receiver operating characteristic (AUROC) for cirrhosis detection by FS improved from 0.921 to 0.945 while specificity increased from 80% to 90% at a sensitivity of 96%. A similar AUROC could be obtained for lower F3 fibrosis stage if LS measurements were restricted to patients with GOT < 50 U/L. Histological grading of inflammation did not further improve the diagnostic accuracy of LS.CONCLUSION:Coexisting steatohepatitis markedly increases LS in patients with ALD independent of fibrosis stage. Postponing cirrhosis assessment by FS during alcohol withdrawal until GOT decreases to < 100 U/mL signif icantly improves the diagnostic accuracy.

Use of shear wave elastography for the diagnosis and follow-up of biliary atresia: A meta-analysis

BACKGROUND Timely differentiation of biliary atresia(BA)from other infantile cholestatic diseases can impact patient outcomes.Additionally,non-invasive staging of fibrosis after Kasai hepatoportoenterostomy has not been widely standardized.Shear wave elastography is an ultrasound modality that detects changes in tissue stiffness.The authors propose that the utility of elastography in BA can be elucidated through meta-analysis of existing studies.AIM To assess the utility of elastography in:(1)BA diagnosis,and(2)post-Kasai fibrosis surveillance.METHODS A literature search identified articles that evaluated elastography for BA diagnosis and for post-Kasai follow-up.Twenty studies met criteria for meta-analysis:Eleven for diagnosis and nine for follow-up post-Kasai.Estimated diagnostic odds ratio(DOR),sensitivity,and specificity of elastography were calculated through a random-effects model using Meta-DiSc software.RESULTS Mean liver stiffness in BA infants at diagnosis was significantly higher than in non-BA,with overall DOR 24.61,sensitivity 83%,and specificity 79%.Post-Kasai,mean liver stiffness was significantly higher in BA patients with varices than in patients without,with DOR 16.36,sensitivity 85%,and specificity 76%.Elastography differentiated stage F4 fibrosis from F0-F3 with DOR of 70.03,sensitivity 96%,and specificity 89%.Elastography also differentiated F3-F4 fibrosis from F0-F2 with DOR of 24.68,sensitivity 85%,and specificity 81%.CONCLUSION Elastography has potential as a non-invasive modality for BA diagnosis and surveillance post-Kasai.This paper’s limitations include inter-study method heterogeneity and small sample sizes.Future,standardized,multi-center studies are recommended.

Liver stiffness and perfusion changes for hepatic sinusoidal obstruction syndrome in rabbit model

BACKGROUND Hepatic sinusoidal obstruction syndrome(SOS)is caused by damage to hepatic sinusoidal endothelial cells that results in fibrous obliteration of intrahepatic venules and necrosis of hepatocytes.Currently the diagnosis is primarily based on nonspecific clinical features and invasive liver biopsy.Therefore,noninvasive imaging methods are required for the early diagnosis and severity assessment of hepatic SOS.AIM To determine the effectiveness of supersonic shear wave imaging(SSI)and dual energy computed tomography(DECT)for diagnosing hepatic SOS using a rabbit model.METHODS Among nine New Zealand white rabbits(3-4 kg,male),three in control group ingested normal saline for 20 d and six in the SOS group ingested 6-thioguanine(5 mg/kg/d)for 20 d.Liver stiffness was measured using SSI on days 0,3,10,and 20.On the same days,liver perfusion was evaluated from virtual monochromatic images of 55 keV and iodine map using DECT.Morphologic changes in the liver were assessed using CT.Final pathology scores were compared between the two groups.Liver stiffness and perfusion parameters were compared according to the groups,days,and pathology scores.RESULTS Final pathology scores were significantly higher in the SOS than the control group(median 22 vs 2,P=0.024).No gross morphologic changes were seen in livers.Liver stiffness,Hounsfield Unit values,and iodine concentrations were higher in the SOS compared to the control group on days 10 and 20(all,P≤0.007).Compared to day 0,liver stiffness and perfusion parameters were higher on day 20 in the SOS group(all,P≤0.001).Correlation coefficients for liver stiffness(r=0.635),Hounsfield Unit values(r=0.587),and iodine concentration(r=0.611)with final pathology scores were positive without significance(all,P>0.05).CONCLUSION Liver stiffness and perfusion parameters were significantly increased in the livers of a rabbit SOS model.SSI and DECT might aid in early diagnosis of hepatic SOS.

Biomimetic nanoparticles drive the mechanism understanding of shear-wave elasticity stiffness in triple negative breast cancers to predict clinical treatment

In clinical practice,we noticed that triple negative breast cancer(TNBC)patients had higher shear-wave elasticity(SWE)stiffness than non-TNBC patients and a higherα-SMA expression was found in TNBC tissues than the non-TNBC tissues.Moreover,SWE stiffness also shows a clear correlation to neoadjuvant response efficiency.To elaborate this phenomenon,TNBC cell membrane-modified polylactide acid-glycolic acid(PLGA)nanoparticle was fabricated to specifically deliver artesunate to regulate SWE stiffness through inhibiting CAFs functional status.As tested in MDA-MB-231 and E0771 orthotopic tumor models,CAFs functional status inhibited by 231M-ARS@PLGA nanoparticles(231M-AP NPs)had reduced the SWE stiffness as well as attenuated hypoxia of tumor as tumor soil loosening agent which amplified the antitumor effects of paclitaxel and PD1 inhibitor.Single-cell sequencing indicated that the two main CAFs(extracellular matrix and wound healing CAFs)that produces extracellular matrix could influence the tumor SWE stiffness as well as the antitumor effect of drugs.Further,biomimetic nanoparticles inhibited CAFs function could attenuate tumor hypoxia by increasing proportion of inflammatory blood vessels and oxygen transport capacity.Therefore,our finding is fundamental for understanding the role of CAFs on affecting SWE stiffness and drugs antitumor effects,which can be further implied in the potential clinical theranostic predicting in neoadjuvant therapy efficacy through non-invasive analyzing of SWE imaging.

Perioperative liver and spleen elastography in patients without chronic liver disease

AIM To investigate changes in hepatic and splenic stiffness in patients without chronic liver disease during liver resection for hepatic tumors.METHODS Patients scheduled for liver resection for hepatic tumors were considered for enrollment. Tissue stiffness measurements on liver and spleen were conducted before and two days after liver resection using point shear-wave elastography. Histological analysis of the resected liver specimen was conducted in all patients and patients with marked liver fibrosis were excluded from further study analysis. Patients were divided into groups depending on size of resection and whether they had received preoperative chemotherapy or not. The relation between tissue stiffness and postoperative biochemistry was investigated. RESULTS Results are presented as median(interquartile range). 35 patients were included. The liver stiffness increased in patients undergoing a major resection from 1.41(1.24-1.63) m/s to 2.20(1.72-2.44) m/s(P = 0.001). No change in liver stiffness in patients undergoing a minor resection was found [1.31(1.15-1.52) m/s vs 1.37(1.12-1.77) m/s, P = 0.438]. A major resection resulted in a 16%(7%-33%) increase in spleen stiffness, more(P = 0.047) than after a minor resection [2(-1-13) %]. Patients who underwent preoperative chemotherapy(n = 20) did not differ from others in preoperative right liver lobe [1.31(1.16-1.50) vs 1.38(1.12-1.56) m/s, P = 0.569] or spleen [2.79(2.33-3.11) vs 2.71(2.37-2.86) m/s, P = 0.515] stiffness. Remnant liver stiffness on the second postoperative day did not show strong correlations with maximum postoperative increase in bilirubin(R^2 = 0.154, Pearson's r = 0.392, P = 0.032) and international normalized ratio(R^2 = 0.285, Pearson's r = 0.534, P = 0.003). CONCLUSION Liver and spleen stiffness increase after a major liver resection for hepatic tumors in patients without chronic liver disease.

Noninvasive diagnosis of periportal fibrosis in schistosomiasis mansoni:A comprehensive review

Schistosomiasis mansoni is a neglected disease and key public health problem,mainly due to its high prevalence,the scarcity of public policies,and the severity of some clinical forms.Periportal fibrosis(PPF)is the commonest complication of chronic schistosomiasis mansoni and its diagnosis requires different techniques.Even though wedge biopsy of the liver is considered the gold standard,it is not justified in non-surgical patients,and percutaneous liver biopsy may be informative but does not have sufficient sensitivity.Noninvasive PPF tests mostly include biological(serum biomarkers or combined scores)or physical assessments(imaging assessment of fibrosis pattern or tissue stiffness).Moreover,imaging techniques,such as ultrasound,computed tomography,magnetic resonance imaging,and elastography are applied not only to support the diagnosis of schistosomiasis,but also to assess and detect signs of portal hypertension and organ damage due to chronic schistosomiasis.A combination between a comprehensive history and physical examination with biomarkers for liver fibrosis and imaging methods seems to offer the best approach for evaluating these patients.In addition,understanding their strengths and limitations will allow a more accurate interpretation in the clinical context and can lead to greater accuracy in estimating the degree of fibrosis in patients with Schistosomiasis mansoni(S.mansoni)infection.This review will discuss the different noninvasive methods that are currently available for the evaluation of PPF in S.mansoni infection,and their application,advantages,and limitations in clinical practice.

Microscopic elasticity imaging of vessel walls based on intravascular ultrasound

The effect of the transducer eccentricity on grayscales of intravascualr ultrasound images was corrected based on the scattering properties of high frequency ultrasound in vessel walls. The displacement and strain distributions of vessel walls produced by tissue microelement motion were obtained using a novel motion estimation method in steps and sum based on the optical flow and genetic algorithm. Furthermore, authors firstly reconstructed 'real' elasticity distribution images of cross section tissues of vessel walls in the world. In vitro experimental results of porcine artery demonstrated the methods mentioned above are reasonable. Experimental investigation of vascular mechanics can be advanced to 2D sub-millimeter microstructure levels. These studies have potential to provide new technology means in monitoring and evaluation of Percutaneous transluminal coronary angioplasty process.

Investigation of Portevin–Le Chatelier Band Strain and Elastic Shrinkage in Al-Based Alloys Associated with Mg Contents

The Portevin–Le Chatelier（PLC） effect in Al–2.30wt%Mg, Al–4.57wt%Mg and Al–6.91wt%Mg alloys has been investigated at various applied strain rates at room temperature in this study. Three-dimensional digital image correlation（3D-DIC） technique was applied to obtaining the further insight into the spatiotemporal characteristics, in particular the influence of Mg content on deformation behaviors. Mg content has a pronounced effect on serration characteristics, including the serration type and amplitude; Mg content tends to weaken the spatial correlation of the propagative bands. Additionally, the serration amplitude linearly increases with the maximum PLC band strain; high Mg content generates a higher PLC band strain at a given serration amplitude compared with low Mg content. Mg content is found to be effective to enhance the serration amplitude, the maximum PLC band strain and also the amount of elastic shrinkage outside PLC bands.

Rapid and robust medical image elastic registration using mean shift algorithm

In landmark-based image registration, estimating the landmark correspondence plays an important role. In this letter, a novel landmark correspondence estimation technique using mean shift algorithm is proposed. Image corner points are detected as landmarks and mean shift iterations are adopted to find the most probable corresponding point positions in two images. Mutual information between intensity of two local regions is computed to eliminate mis-matching points to improve the stability of corresponding estimation correspondence landmarks is exact. The proposed experiments of various mono-modal medical images. Multi-level estimation （MLE） technique is proposed Experiments show that the precision in location of technique is shown to be feasible and rapid in the

Elastic deformation behavior of CuZrAlNb metallic glass matrix composites with different crystallization degrees

The room temperature brittleness has been a long standing problem in bulk metallic glasses realm.This has seriously limited the application potential of metallic glasses and their composites.The elastic deformation behaviors of metallic glass matrix composites are closely related to their plastic deformation states.The elastic deformation behaviors of Cu48-xZr48Al4Nbx（x=0,3at.%）metallic glass matrix composites（MGMCs）with different crystallization degrees were investigated using an in-situ digital image correlation（DIC）technique during tensile process.With decreasing crystallization degree,MGMC exhibits obvious elastic deformation ability and an increased tensile fracture strength.The notable tensile elasticity is attributed to the larger shear strain heterogeneity emerging on the surface of the sample.This finding has implications for the development of MGMCs with excellent tensile properties.

Diagnostic performance of elastography on liver fibrosis in antiviral treatment-naive chronic hepatitis B patients:a meta-analysis

Background:This study aimed to assess the performance of transient elastography(TE),two-dimensional shear wave elastography(2D-SWE),and magnetic resonance elastography(MRE)for staging significant fibrosis and cirrhosis in untreated chronic hepatitis B(CHB)patients.Methods:Pubmed,Embase,Web of Science,and Cochrane Library were searched for terms involving CHB,TE,2D-SWE,and MRE.Other etiologies of chronic liver disease,previous treatment in patients,or articles not published in SCI journals were excluded.Hierarchical non-linear models were used to evaluate the diagnostic accuracy of TE,2D-SWE,and MRE.Heterogeneity was explored via analysis of threshold effect and meta-regression.Results:Twenty-eight articles with a total of 4,540 untreated CHB patients were included.The summary areas under the receiver-operating characteristic curves(AUROCs)using TE,2D-SWE,and MRE for predicting significant fibrosis(SF)were 0.84,0.89,and 0.99,respectively.The AUROC values of TE,2D-SWE,and MRE for staging cirrhosis were 0.9,0.94,and 0.99,respectively.Based on the meta-analysis of studies with head-to-head comparison,2D-SWE is superior to TE(0.92 vs 0.85,P<0.01)in staging significant fibrosis.Conclusion:TE,2D-SWE,and MRE express acceptable diagnostic accuracies in staging significant fibrosis and cirrhosis in untreated CHB patients.2D-SWE outperforms TE in detecting significant fibrosis in treatment-naive people with hepatitis B virus.

Elastogram:Physics,Clinical Applications,and Risks

The tissue stiffness is always an interesting issue to clinicians.Traditionally,it is assessed by the manual palpation,and this now can be measured by the ultrasound-based elastography.The basic physics is based on Young's modulus through the Hooke's law:E=S/e,where the Young's modulus(E)equals to the stress applied to the object(S)divided by the generated strain(e).With the rapid advancement of technology,the elastography has evolved from quasi-static elastography(ie,strain elastography)to dynamic elastography(i,e,shear wave elastography).The key differentiation of these two categories roots in the stimuli applied,namely mechanical or acoustic radiation force,and the response of the soft tissue.The strain elastography requires the operator to compress and decompress the tissue manually and the motion of the tissue during the stimuli is tracked to calculate the strain to reflect the tissue stiffness.While strain elastography is operator-dependent,shear wave elastography is not.Using shear wave elastography,the tissue is stimulated by the acoustic radiation force which can generate shear wave traveling through the tissue transversely.The shear wave propagation speed(Vs)is related to the shear modulus(μ)of the medium:μ=pVs^(2),where p is the density of the tissue and assumed to be a constant as 1000 kg/m^(3).In the incompressible biological tissue,the Young's modulus is approximately three times the shear modulus(E≈3μ).So the quantitative measurements of the tissue stiffness can be attained by shear wave elastography.The clinical application of elastography and its diagnostic capability has been extended.The knowledge of the basic physics of the various type of elastography facilitates the effective use of elastography.This review presented the clinical application and the risks of different types of elastography.