Photoacoustic elastography based on laser-excited shear wave

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.

Predicting hepatocellular carcinoma: A new non-invasive model based on shear wave elastography

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.

Seismic anisotropy and upper mantle dynamics in Alaska:A review of shear wave splitting analyses

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.

Comparison of resistive index and shear-wave elastography in the evaluation of chronic kidney allograft dysfunction

BACKGROUND Detection of early chronic changes in the kidney allograft is important for timely intervention and long-term survival.Conventional and novel ultrasound-based investigations are being increasingly used for this purpose with variable results.AIM To compare the diagnostic performance of resistive index(RI)and shear wave elastography(SWE)in the diagnosis of chronic fibrosing changes of kidney allograft with histopathological results.METHODS This is a cross-sectional and comparative study.A total of 154 kidney transplant recipients were included in this study,which was conducted at the Departments of Transplantation and Radiology,Sindh Institute of Urology and Transplantation,Karachi,Pakistan,from August 2022 to February 2023.All consecutive patients with increased serum creatinine levels and reduced glomerular filtration rate(GFR)after three months of transplantation were enrolled in this study.SWE and RI were performed and the findings of these were evaluated against the kidney allograft biopsy results to determine their diagnostic utility.RESULTS The mean age of all patients was 35.32±11.08 years.Among these,126(81.8%)were males and 28(18.2%)were females.The mean serum creatinine in all patients was 2.86±1.68 mg/dL and the mean estimated GFR was 35.38±17.27 mL/min/1.73 m2.Kidney allograft biopsy results showed chronic changes in 55(37.66%)biopsies.The sensitivity,specificity,positive predictive value(PPV),and negative predictive value(NPV)of SWE for the detection of chronic allograft damage were 93.10%,96.87%%,94.73%,and 95.87%,respectively,and the diagnostic accuracy was 95.45%.For RI,the sensitivity,specificity,PPV,and NPV were 76.92%,83.33%,70.17%,and 87.62%,respectively,and the diagnostic accuracy was 81.16%.CONCLUSION The results from this study show that SWE is more sensitive and specific as compared to RI in the evaluation of chronic allograft damage.It can be of great help during the routine follow-up of kidney transplant recipients for screening and early detection of chronic changes and selecting patients for allograft biopsy.

Analytical solutions of turbulent boundary layer beneath forward-leaning waves

As a typical nonlinear wave,forward-leaning waves can be frequently encountered in the near-shore areas,which can impact coastal sediment transport significantly.Hence,it is of significance to describe the characteristics of the boundary layer beneath forward-leaning waves accurately,especially for the turbulent boundary layer.In this work,the linearized turbulent boundary layer model with a linear turbulent viscosity coefficient is applied,and the novel expression of the near-bed orbital velocity that has been worked out by the authors for forward-leaning waves of arbitrary forward-leaning degrees is further used to specify the free stream boundary condition of the bottom boundary layer.Then,a variable transformation is found so as to make the equation of the turbulent boundary layer model be solved analytically through a modified Bessel function.Consequently,an explicit analytical solution of the turbulent boundary layer beneath forward-leaning waves is derived by means of variable separation and variable transformation.The analytical solutions of the velocity profile and bottom shear stress of the turbulent boundary layer beneath forward-leaning waves are verified by comparing the present analytical results with typical experimental data available in the previous literature.

Shear wave splitting analysis of local earthquakes from dense arrays in Shimian,Sichuan

The Shimian area of Sichuan sits at the junction of the Bayan Har block.Sichuan-Yunnan rhombic block,and Yangtze block,where several faults intersect.This region features intense tectonic activity and frequent earthquakes.In this study,we used local seismic waveform data recorded using dense arrays deployed in the Shimian area to obtain the shear wave splitting parameters at 55 seismic stations and thereby determine the crustal anisotropic characteristics of the region.We then analyzed the crustal stress pattern and tectonic setting and explored their relationship in the study area.Although some stations returned a polarization direction of NNW-SSE.a dominant polarization direction of NW-SE was obtained for the fast shear wave at most seismic stations in the study area.The polarization directions of the fast shear wave were highly consistent throughout the study-area.This orientation was in accordance with the direction of the regional principal compressive stress and parallel to the trend of the Xianshuihe and Daliangshan faults.The distribution of crustal anisotropy in this area was affected by the regional tectonic stress field and the fault structures.The mean delay time between fast and slow shear waves was 3.83 ms/km.slightly greater than the values obtained in other regions of Sichuan.This indicates that the crustal media in our study area had a high anisotropic strength and also reveals the influence of tectonic complexity resulting from the intersection of multiple faults on the strength of seismic anisotropy.

Combining the age-male-albumin-bilirubin-platelets score and shear wave elastography stratifies carcinogenic risk in hepatitis C patients after viral clearance

BACKGROUND The treatment of hepatitis C with direct-acting antiviral agents(DAAs)produces a high rate of sustained virological response(SVR)with fewer adverse events than interferon(IFN)therapy with a similar effect in inhibiting carcinogenesis as IFN therapy.The age-male-albumin-bilirubin-platelets(aMAP)score is useful for stratifying the risk of hepatocellular carcinoma in chronic hepatitis patients,and the velocity of shear waves(Vs)measured by shear wave elastography has also been shown to be useful for diagnosing the level of fibrotic progression in hepatitis C and predicting carcinogenic risk.Combining these two may improve the prediction of carcinogenic risk.AIM To determine whether combining the aMAP score with Vs improves carcinogenic risk stratification in medium-to-high-risk hepatitis C patients.METHODS This retrospective,observational study involved hepatitis C patients treated with DAAs who achieved SVR.Vs was measured before treatment(baseline),at the end of treatment(EOT),and 12 wk(follow-up 12)and 24 wk(follow-up 24)after treatment.The patients were followed for at least six months after EOT to determine whether cancer developed.Multiple regression analysis was used to identify factors contributing to hepatic carcinogenesis.The diagnostic performances of clinical parameters for predicting the presence of hepatocellular carcinoma were evaluated using receiver-operating characteristic(ROC)curve analyses.RESULTS A total of 279 patients(mean age 65.9 years,118 males,161 females)were included in the analysis.Multiple regression analysis was performed with carcinogenesis as the target variable and alanine aminotransferase,platelets,α-fetoprotein,Vs,and the Fib-4 index as explanatory variables;only Vs was found to be significant(P=0.0296).The cut-off value for Vs for liver carcinogenesis calculated using the ROC curve was 1.53 m/s.Carcinoma developed in 2.0%(3/151)of those with Vs<1.53 m/s and in 10.5%(9/86)of those with Vs≥1.53 m/s.CONCLUSION In hepatitis C patients after SVR,combining the aMAP score and Vs to stratify the risk of carcinogenesis is more efficient than uniform surveillance of all patients.

Comparative analysis of conventional ultrasound and shear wave elastography features in primary breast diffuse large B-cell lymphoma

BACKGROUND Primary breast diffuse large B-cell lymphoma(PB-DLBCL)is a rare subtype of non-Hodgkin lymphoma that accounts for<3%of extranodal lymphomas and 1%of breast tumors.Its diagnosis and management are challenging because of its rarity,heterogeneity,and aggressive behavior.Conventional ultrasound(US)is the first-line imaging modality for breast lesions;however,it has limited specificity and accuracy for PB-DLBCL.Shear wave elastography(SWE)is a novel US technique that measures tissue stiffness and may reflect the histological characteristics and biological behavior of breast lesions.AIM To compare the conventional US and SWE features of PB-DLBCL and evaluate their diagnostic performance and prognostic value.METHODS We retrospectively reviewed the clinical data and US images of 32 patients with pathologically confirmed PB-DLBCL who underwent conventional US and SWE before treatment.We analyzed conventional US features(shape,margin,orientation,echo,posterior acoustic features,calcification,and vascularity)and SWE features(mean elasticity value,standard deviation,minimum elasticity value,maximum elasticity value,and lesion-to-fat ratio)of the PB-DLBCL lesions.Using receiver operating characteristic curve analysis,we determined the optimal cutoff values and diagnostic performance of conventional US and SWE features.We also performed a survival analysis to assess the prognostic value of conventional US and SWE features.RESULTS The results showed that the PB-DLBCL lesions were mostly irregular in shape(84.4%),microlobulated or spiculated in margins(75%),parallel in orientation(65.6%),hypoechoic in echo(87.5%),and had posterior acoustic enhancement(65.6%).Calcification was rare(6.3%)and vascularity was variable(31.3%avascular,37.5%hypovascular,and 31.3%hypervascular).The mean elasticity value of PB-DLBCL lesions was significantly higher than that of benign breast lesions(113.4±46.9 kPa vs 27.8±16.4 kPa,P<0.001).The optimal cutoff value of the mean elasticity for distinguishing PB-DLBCL from benign breast lesions was 54.5 kPa,with a sensitivity of 93.8%,specificity of 92.9%,positive predictive value of 93.8%,negative predictive value of 92.9%,and accuracy of 93.3%.The mean elasticity value was also significantly correlated with Ki-67 expression level(r=0.612,P<0.001),which is a marker of tumor proliferation and aggressiveness.Survival analysis showed that patients with higher mean elasticity values(>54.5 kPa)had worse overall survival(OS)and progression-free survival(PFS)than those with lower mean elasticity values(<54.5 kPa)(P=0.038 for OS and P=0.027 for PFS).CONCLUSION Conventional US and SWE provide useful information for diagnosing and forecasting PB-DLBCL.SWE excels in distinguishing PB-DLBCL from benign breast lesions,reflects tumor proliferation and aggressiveness,and improves disease management.

Optimization design of conical reaction teeth of shear wave vibroseis vibration plate

The vibrator plate is the link between the vibroseis vehicle and the earth,as well as the core com-ponent of the vibrator vehicle.In this paper,the coupling effect between the vibrator plate and the earth is an-alyzed from two aspects of reaction tooth arrangement and reaction tooth conical angle,and three groups of experimental models are optimized and designed.The model construction and numerical analysis of the shear wave vibroseis vibrator plate are carried out with ANSYS software.The motion law between the vibration plate and the earth at work was studied,the strain energy of the three experimental models in operation,the maximum displacement of particle at the same position and other reference indices were compared and ana-lyzed,with 28 conical reaction teeth were arranged on both sides.The coupling effect between the vibration plate and the earth was best when the tooth angle was 60°.Compared with the toothless vibration plate,the energy efficiency is improved by about 20%,and the coupling effect between the vibrator plate and the earth is effectively enhanced.It is found that the coupling effect is enhanced through increasing the number of reac-tion teeth of the vibration plate by increasing the coupling area between the vibration plate and the earth.

Real-time Shear Wave Elastography Assessment of Muscle Elasticity in Patients with Renal Failure

Objective:To explore the value of real-time elastic shear wave in evaluating muscle elasticity in patients with renal failure.Methods:50 patients with chronic renal failure from January 2019 to December 2022 were randomly selected as the experimental group,and 50 healthy patients aged 21-61 during the same period were selected as the control group,and the basic information of the patients,including age,gender,body mass index,etc.,were collected.Besides,the Young's modulus of the two groups of patients were observed and analyzed.Results:The Young's modulus values of left and right gastrocnemius muscles in the experimental group were significantly lower than those in the control group(P<0.05),and there was no statistical difference between the left and right sides of the experimental group and the control group(P>0.05).Conclusion:Real-time shear wave elastography provides a non-invasive,real-time and effective tool for the assessment of muscle elasticity in patients with renal failure.Through further research and optimization,real-time shear wave elastography will play a greater role in the prevention and treatment of patients with renal failure,improving the quality of life and prognosis of patients.

Assessment of Calf Skeletal Muscle Stiffness in Diabetic Nephropathy Patients with Medial Tibial Stress Syndrome by Two-Dimensional Shear Wave Elastography

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.

Shear-wave splitting beforeand after the 1999 Xiuyan earthquake in Liaoning, China

Using seismic waveform data recorded at station YK (Yingkou) of Liaoning Telemetry Digital Seismic Network, this paper studied the characteristics of shear-wave splitting before and after the Xiuyan MS5.9 (ML5.3) earthquake in November 29, 1999 with SAM method. The results show that the predominant polarizations of fast shear-waves at YK is in direction of ENE-WSW, consistent with the direction of regional principal compressive stress and also consistent with the direction of the regional tectonic stress field in North China; time-delays increasing before Xiuyan earthquake may shows accumulation of stress before earthquake. The predominant polarizations of fast shear-waves at YK are also related to the spatial distribution of small earthquakes and correlate with the fault strike. The histogram of monthly average polarizations of fast shear-waves shows that polarizations of fast shear-waves also seems to change from two months before the earthquake, but it still needs more data for verification.

Variational characteristics of shear-wave splitting on the 2001 Shidian earthquakes in Yunnan, China

In 2001 three earthquakes occurred in Shidian in Yunnan Province, which were the MS=5.2 on April 10, the MS=5.9 on April 12 and the MS=5.3 on June 8. Based on the data from the station Baoshan of Yunnan Telemetry Digital Seismograph Network, the variational characteristics of shear-wave splitting on these series of strong earthquakes has been studied by using the systematic analysis method (SAM) of shear-wave splitting. The result shows the time delays of shear-wave splitting basically increase with earthquake activity intensifying. However the time delays abruptly decrease immediately before strong aftershocks. It accords with the stress relaxation before earthquakes, which was found recently in study on shear-wave splitting. The result suggests it is significant for reducing the harm degree of earthquakes to develop the stress-forecasting on earthquake in strong active tectonic zones and economic developed regions or big cities under the danger of strong earthquakes.

Three dimensional shear wave velocity structure of crust and upper mantle in South China Sea and its adjacent regions by surface waveform inversion

We assembled approximately 328 seismic records. The data set was from 4 digitally recording long-period and broadband stations of CDSN. We carried out the inversion based on the partitioned waveform inversion (PWI). It partitions the large-scale optimization problem into a number of independent small-scale problems. We adopted surface waveform inversion with an equal block (2((2() discretization in order to acquire the images of shear velocity structure at different depths (from surface to 430 km) in the crust and upper-mantle. The resolution of all these anomalies has been established with (check-board( resolution tests. These results show significant difference in velocity, lithosphere and asthenosphere structure between South China Sea and its adjacent regions.

Quantitative and noninvasive assessment of chronic liver diseases using two-dimensional shear wave elastography

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.

Shear wave velocity is a useful marker for managing nonalcoholic steatohepatitis

AIM:To investigate whether a noninvasive measurement of tissue strain has a potential usefulness for management of nonalcoholic steatohepatitis(NASH).METHODS:In total 26 patients,23 NASHs and 3 normal controls were enrolled in this study.NASH was staged based on Brunt criterion.At a region of interest(ROI),a shear wave was evoked by implementing an acoustic radiation force impulse(ARFI),and the propagation velocity was quantif ied.RESULTS:Shear wave velocity(SWV) could be reproducibly quantified at all ROIs in all subjects except for 4 NASH cases,in which a reliable SWV value was not calculated at several ROIs.An average SWV of 1.34 ± 0.26 m/s in fibrous stage 0-1 was significantly slower than 2.20 ± 0.74 m/s and 2.90 ± 1.01 m/s in stages 3 and 4,respectively,but was not significantly different from 1.79 ± 0.78 m/s in stage 2.When a cutoff value was set at 1.47 m/s,receiver operating characteristic analysis showed significance to dissociate stages 3 and 4 from stage 0-1(P=0.0092) with sensitivity,specificity and area under curve of 100%,75% and 94.2%,respectively.In addition,the correlation between SWV and hyaluronic acid was significant(P<0.0001),while a tendency toward negative correlation was observed with serum albumin(P=0.053).CONCLUSION:The clinical implementation of ARFI provides noninvasive repeated evaluations of liver stiffness at an arbitrary position,which has the potential to shed new light on NASH management.

Shear-wave splitting beneath Yunnan area of Southwest China

Systematic analyses of seismic data recorded by the Yunnan regional seismograph network reveal significant crustal and upper mantle anisotropy. Splitting of the S phase of local earthquakes and teleseismic SKS, PKS, and SKKS phases indicates time-delays from 1.60 ms/km to 2.30 ms/km in the crust, and from 0.55 s to 1.65 s in the upper mantle which corresponds to an The polarization orientations of fast shear waves in direction, and the mantle anisotropy has a nearly styles and mechanisms exist between the crust and anisotropic layer with a thickness about between 55 165 km. the crust are complicated with a predominantly north-south west-east direction. Our results show different deformation upper mantle.

Shear wave velocity-based liquefaction evaluation in the great Wenchuan earthquake: a preliminary case study

The great Wenchuan earthquake （Ms= 8.0） in 2008 caused severe damage in the western part of the Chengdu Plain. Soil liquefaction was one of the major causes of damage in the plain areas, and proper evaluation of liquefaction potential is important in the definition of the seismic hazard facing a given region and post-earthquake reconstruction. In this paper, a simplified procedure is proposed for liquefaction assessment of sandy deposits using shear wave velocity （V）, and soil liquefaction from the Banqiao School site was preliminarily investigated after the earthquake. Boreholes were made at the site and shear wave velocities were measured both by SASW and down-hole methods. Based on the in-situ soil information and V profiles, the liquefaction potential of this site was evaluated. The results are reasonably consistent with the actual field behavior observed after the earthquake, indicating that the proposed procedure is effective. The possible effects of gravel and fines contents on liquefaction of sandy soils were also briefly discussed.

Shear wave elastography results correlate with liver fibrosis histology and liver function reserve

AIM: To evaluate the correlation of shear wave elastography(SWE) results with liver fibrosis histology and quantitative function reserve.METHODS: Weekly subcutaneous injection of 60% carbon tetrachloride(1.5 m L/kg) was given to 12 canines for 24 wk to induce experimental liver fibrosis, with olive oil given to 2 control canines. At 24 wk, liver condition was evaluated using clinical biochemistry assays, SWE imaging, lidocaine metabolite monoethylglycine-xylidide(MEGX) test, and histologic fibrosis grading. Clinical biochemistry assays were performed at the institutional central laboratory for routine liver function evaluation. Liver stiffness was measured in triplicate from three different intercostal spaces and expressed as mean liver stiffness modulus(LSM). Plasma concentrations of lidocaine and its metabolite MEGX were determined using high-performance liquid chromatography repeated in duplicate. Liver biopsy samples were fixed in 10% formaldehyde, and liver fibrosis was graded using the modified histological activity index Knodell score(F0-F4). Correlations among histologic grading, LSM, and MEGX measures were analyzed with the Pearson linear correlation coefficient.RESULTS: At 24 wk liver fibrosis histologic grading was as follows: F0, n = 2(control); F1, n = 0; F2, n = 3; F3, n = 7; and F4, n = 2. SWE LSM was positively correlated with histologic grading(r = 0.835, P < 0.001). Specifically, the F4 group had a significantly higher elastic modulus than the F3, F2, and F0 groups(P = 0.002, P = 0.003, and P = 0.006, respectively), and the F3 group also had a significantly higher modulus than the control F0 group(P = 0.039). LSM was negatively associated with plasma MEGX concentrations at 30 min(r =-0.642; P = 0.013) and 60 min(r =-0.651; P = 0.012), time to ? of the maximum concentration(r =-0.538; P = 0.047), and the area under the curve(r =-0.636; P = 0.014). Multiple comparisons showed identical differences in these three measures: significantly lower with F4(P = 0.037) and F3(P = 0.032) as compared to F0 and significantly lower with F4 as compared to F2(P = 0.032).CONCLUSION: SWE LSM shows a good correlation with histologic fibrosis grading and pharmacologic quantitative liver function reserve in experimental severe fibrosis and cirrhosis.

Crack－induced anisotropy in the crust from shear wave splitting observed in Tangshan region，North China

Using the cross correlation function analysis method, this paper discusses shear wave splitting and crack-inducedanisotropy in the crust beneath Tangshan, North China, by the digital data from Tangshan strong ground monon temporary arrays. Sixteen of twenty-one stations in the arrays recorded earthquake events available forstudying from 1982 to 1984. Having calculated 131 available records, we get slower shear wave time delay r andfaster shear wave polarization azimuth Paz in Tangshan region, and the cracks density s is got further fromthem. The analysis shows that the stress field is very complicated in Tangshan region and has strongly regionalfeature. Because of the complicated distribution of faults, different shear wave splitting characteristics are shownin 16 stations, scattered r and different Paz. And they also were observed that the r and PaZ values were diversewithin the time scale of hours in more than one station. In Tangshan region the average results of r, Paz and Bare 0. 0071 s. km-1, northwest-west near to east-west and 0.022 respectively. Meantime, the standard devia.tions were calculated in this paper.