Shear Wave Velocity Research Articles

Uncertainty Quantification in Shear Wave Velocity Predictions: Integrating Explainable Machine Learning and Bayesian Inference

The accurate prediction of shear wave velocity (Vs) is critical for earthquake engineering applications. However, the prediction is inevitably influenced by geotechnical variability and various sources of uncertainty. This paper investigates the effectiveness of integrating explainable machine learning (ML) model and Bayesian generalized linear model (GLM) to enhance both predictive accuracy and uncertainty quantification in Vs prediction. The study utilizes an Extreme Gradient Boosting (XGBoost) algorithm coupled with Shapley Additive Explanations (SHAPs) and partial dependency analysis to identify key geotechnical parameters influencing Vs predictions. Additionally, a Bayesian GLM is developed to explicitly account for uncertainties arising from geotechnical variability. The effectiveness and predictive performance of the proposed models were validated through comparison with real case scenarios. The results highlight the unique advantages of each model. The XGBoost model demonstrates good predictive performance, achieving high coefficient of determination (R2), index of agreement (IA), Kling–Gupta efficiency (KGE) values, and low error values while effectively explaining the impact of input parameters on Vs. In contrast, the Bayesian GLM provides probabilistic predictions with 95% credible intervals, capturing the uncertainty associated with the predictions. The integration of these two approaches creates a comprehensive framework that combines the strengths of high-accuracy ML predictions with the uncertainty quantification of Bayesian inference. This hybrid methodology offers a powerful and interpretable tool for Vs prediction, providing engineers with the confidence to make informed decisions.

Shear wave elastography primer for the abdominal radiologist.

Shear wave elastography (SWE) provides a means for adding information about the mechanical properties of tissues to a diagnostic ultrasound examination. It is important to understand the physics and methods by which the measurements are made to aid interpretation of the results as they relate to disease processes. The components of how ultrasound is used to generate shear waves and make measurements of the induced motion are reviewed. The physics of shear wave propagation are briefly described for elastic and viscoelastic tissues. Additionally, shear wave propagation in homogeneous and inhomogeneous cases is addressed. SWE technology has been implemented by many clinical vendors with different capabilities. Various quality metrics are used to define valid measurements based on aspects of the shear wave signals or wave velocity estimates. There are many uses for SWE in abdominal imaging, but it is important to understand how the measurements are performed to gauge their utility for diagnosis of different conditions. Continued efforts to make the technology robust in complex clinical situations are ongoing, but many applications actively benefit from added information about tissue mechanical properties for a more holistic view of the patient for diagnosis or assessment of prognosis and treatment management.

Predictive Models of Deep Shear Wave Velocity Profiles at Excavated Rock Sites in Korea

Predictive Models of Deep Shear Wave Velocity Profiles at Excavated Rock Sites in Korea

Shear wave velocity exhibits significant beat-to-beat variability in atrial fibrillation

Abstract Background Shear wave elastography (SWE), by measuring the propagation velocity of naturally occurring myocardial shear waves after mitral valve closure (MVC), provides real-time insights into myocardial stiffness. Previous studies have focused solely on patients with regular heart rhythm and investigated the impact of steady state loading conditions on shear wave velocities (SWV). However, the effect of beat-to-beat variations in loading due to changes in cardiac cycle length (CL) remains unknown. Purpose To investigate if SWV are influenced by beat-to-beat changes in cardiac CL. Methods 30 consecutive patients were included: 20 with persistent/permanent atrial fibrillation (Afib) and 10 in sinus rhythm (SR). Conventional transthoracic echocardiographic images and high frame rate images (1133±90 fps) were obtained. For SWE, 5-10 consecutive cardiac cycles were recorded from parasternal long axis views. Offline analysis of SWV after MVC was performed by drawing an M-mode line along the interventricular septum and semi-automatically measuring the spatiotemporal slope of the wavefront on the M-mode displays, which were color coded for tissue acceleration (Figure A). Beat-to-beat relative variability in SWV and CL was assessed as: (highest value–lowest value)/highest valuex100%. Percentage variation from the mean value per patient was calculated as: (measured value-mean value)/mean valuex100%. The SWV variability index was calculated by normalizing the SWV measured after the longest cardiac cycle (SWVmaxRR) to the SWV measured after the shortest cardiac cycle (SWVminRR) using the formula: (SWVmaxRR- SWVminRR)/SWVmaxRRx100%. Multiple linear regression identified variables associated with the SWV variability index. Results Patients with Afib were older (72±8 years vs. 58±9 years, p<0.001), with a larger left atrial volume index (LAVi) and a lower ejection fraction (EF). Significant differences were observed between patients with and without Afib in CL relative variability (43.0±10.5% vs. 4.2±3.3%, p<0.0001; Figure B) and SWV relative variability (41.8±13.9% vs. 20.2±8.4%, p<0.0001; Figure C). There was a moderate correlation between SWV and CL when normalized to the mean value per patient (r=0.5026, p<0.0001; Figure D). Univariate linear regression analysis showed that age (p=0.001), EF (p=0.03), LAVi (p=0.03), and CL relative variability (p<0.001) were significantly associated with the SWV variability index. In the multivariate model, only CL relative variability remained significantly associated with the SWV variability index (β=0.42; p<0.001). Conclusions Afib leads to greater beat-to-beat variability in SWV measurements compared to SR, with moderate positive correlation between SWV and CL. We hypothesize that a longer filling time leads to increased preload, which is then reflected in higher end-diastolic stiffness of the myocardium. Invasive studies would be desirable to investigate this phenomenon further.

Ultrasound shear wave elastography for detection of myocardial fibrosis

Abstract Background Myocardial fibrosis has important clinical and prognostic implications. Cost-effective imaging tools for fibrosis screening to enable personalized therapies are thus of major interest. Echocardiographic shear wave (SW) elastography is an emerging approach for measuring myocardial stiffness (MS). SWs occur after mechanical excitation of the myocardium, e.g. after mitral valve closure (MVC,i.e natural SW), and their propagation velocity is directly related to MS. Purpose To investigate if natural SW velocities can detect myocardial fibrosis. Methods We included 99 subjects (31 heart transplant patients[52±17years, 77% male], 23 patients with hypertrophic cardiomyopathy [55±16 years, 78% male] and 45 healthy volunteers [HV, 44±17 years, 71% male]). SW elastography was performed in parasternal long axis views of the left ventricle (LV) using an experimental scanner (HD-PULSE) at 1134±255 frames per second. Tissue acceleration maps were extracted from an anatomical M-mode line along the midline of the LV septum. SW propagation velocity at MVC was measured as slope in the M-mode image. Patients underwent besides conventional echocardiography also 1.5T cardiac magnetic resonance with T1 mapping as well as late gadolinium enhancement (LGE) to assess the presence of myocardial fibrosis (Fig 1). Subjects were divided into 4 groups: HV, patients with no fibrosis (NF), interstitial fibrosis (MIF) and replacement fibrosis (MRF). Results SW velocities differed significantly among groups (p<0.0001, Fig 2A). The NF group showed higher SW velocities than HV (4.3±1.3 vs. 3.4±0.9 m/s, p=0.02), while both MIF and MRF groups showed significantly higher values than NF subjects (6.5±1.1 and 8.7±1.2 m/s, respectively). SW velocity showed significant correlations with ECV values (r=0.70) and T1 values (r=0.47), and markers of LV diastolic function (E/e’: r=0.54; isovolumetric relaxation time: r=0.41; deceleration time: r=0.30 (all p<0.01)(Fig 2B-D). A cut-off SW velocity of 3.86m/s allowed to differentiate between HV and the NF group with a sensitivity of 65% and a specificity of 76% (area under the curve (AUC)= 0.73). A cut-off of 4.58 m/s distinguished between HV and all patient groups (sensitivity 95%, specificity 73%, AUC 0.88). SW velocities below 6.01 m/s showed highest accuracy to identify patients without any type of fibrosis (sensitivity 97%, specificity 90%, AUC=0.97). A cut-off of 8.11 m/s could distinguish MRF from MIF with a sensitivity and specificity of 100% and 69%, respectively (AUC=0.92). Conclusions SW velocity measurements can differentiate between fibrotic myocardium and healthy tissue with very good accuracy. Different types of fibrosis (interstitial vs. replacement) could also be distinguished. Nevertheless, we hypothesize that stiffness changes relate mainly to the fibrosis burden. Shear wave elastography appears as promising new tool for the non-invasive assessment of myocardial fibrosis.

Natural shear wave elastography reveals hidden cardiac dysfunction in adult survivors of childhood cancer during cardiopulmonary stress testing

Abstract Background Hidden cardiotoxicity in adult survivors of childhood cancer may carry significant prognostic implications. Many of these survivors are asymptomatic at rest but show impaired cardiorespiratory fitness during exercise. Stress echocardiography combined with cardiopulmonary exercise testing (CPET) can reveal hidden diastolic dysfunction, although it presents major challenges. High frame rate (HFR) natural shear wave (SW) imaging is emerging as an innovative method for assessing myocardial stiffness, a key determinant of diastolic function. Purpose We investigated the relationship between natural SW measured at rest as a marker of myocardial stiffness and patient performance during CPET as markers of cardiorespiratory fitness. Methods A total of 115 subjects; 72 cancer survivors (mean age 20 ±4 years) and 43 matched healthy volunteers (HV) were recruited. We acquired both conventional as well as high frame rate echocardiographic images (ca. 1200 frames/second) at rest. During an incremental, symptom-limited cardiopulmonary exercise test on a treadmill, both peak and efficiency of oxygen consumption (VO2 peak and VO2/work slope) were recorded. All HFR data were analysed offline by drawing an anatomical M-mode along the ventricular septum in the parasternal long axis view, colour coded for tissue acceleration. SW after mitral valve closure (MVC) appeared as green bands and their velocities were measured by estimating the slope semi-automatically. Results In our survivors’ cohort, the prevalence of cardiac dysfunction based on reduced global longitudinal strain was 9.7%. In a univariate regression model, predictors of peak VO2 were age, body mass index (BMI), systolic blood pressure (SBP), left ventricular end-diastolic diameter (LVEDD), left atrial volume indexed (LAVi), mitral inflow to mitral relaxation velocity ratio (E/e’) and SW velocities after MVC. In the multivariate model, SW velocities remained as the strongest predictor for peak VO2, followed by LVEDD, BMI and SBP (Figure 1). Moreover, natural SWs correlate significantly with both peak VO2 and VO2/work slope (r= -0.65; p <0.001, and r=-0.31; p =0.002 respectively) (Figure 2A&B). Interestingly, SW velocities were on average significantly higher in survivors with reduced peak VO2 (non-fit survivors) compared to both survivors with normal peak VO2 (fit survivors) and HV (4.2 ±0.6 m/s vs 3.5 ±0.5 m/s & 3.2 ±0.3 m/s respectively; p <0.001) (Figure 2C). Conclusions Our preliminary data indicate that natural SW velocities measured at rest are related to cardiorespiratory fitness and can identify hidden cardiac dysfunction among childhood cancer survivors. Natural SW elastography appears as promising and innovative echocardiographic parameter for early detection of cardiac dysfunction in follow-up of adult survivors of childhood cancer. Figure 1 Figure 2

Increased myocardial stiffness as assessed by echocardiographic shear wave imaging is associated with Fontan circulatory failure

Abstract Background Diastolic dysfunction with elevated end-diastolic pressures is a key component of Fontan circulatory failure. However, conventional echocardiographic parameters of diastolic function do not correlate with invasive pressures in Fontan patients. Natural shear waves (SW) are emerging as a novel echocardiographic parameter of myocardial stiffness, a key determinant of diastolic function. Purpose We investigated the relationship between natural SW velocities and Fontan circulatory failure. Methods Fontan patients were prospectively recruited from a single center. They underwent a blood sampling for NT-proBNP and cardiopulmonary exercise testing on a supine bicycle combined with echocardiography and with peripheral venous pressure (PVP) measurement. PVP correlates with mean pulmonary arterial pressure in Fontan patients, and a PVP/cardiac output (CO) slope > 3 is associated with worse clinical status. In addition, high frame rate SW imaging was performed at rest in the parasternal long axis view. An anatomic M-mode was drawn along the ventricular septum, or if absent, in the corresponding anterior wall. In the color-coded M-mode maps for tissue acceleration, SW appear as tilted green bands after atrio-ventricular valve closure (AVVC), the slope of which represents their propagation velocity. A clinical diagnosis of Fontan circulatory failure was defined as one the following: dyspnea on exertion with NT-proBNP >300 ng/l, need for diuretics, a peak oxygen consumption (VO2) inferior to the lowest quartile according to age- and sex-adjusted Fontan norms, Fontan associated liver disease complicated by ascites or hepatocellular carcinoma, or protein losing enteropathy. Results Twenty-nine Fontan patients were included, of which 48.3% were female and 82.76% had a dominant left ventricle. The mean age was 33.7 ±8.6 years, the mean peak VO2 19.9 ± 5.9 ml/min/kg and the median NT-proBNP 225 ng/l (IQR 52-473.5). SW velocities increased with age (r = 0.63, p < 0.001) and time since Fontan palliation (r = 0.53, p = 0.005, Figure 1A). In addition, SW velocities significantly correlated with unfavorable clinical parameters: lower peak VO2 (r = -0.76, p < 0.001), elevated NT-proBNP (r = 0.53, p = 0.003) and an increased PVP/CO slope (r = 0.66, p < 0.001) (Figure 1 B-D). Of interest, SW velocities were significantly higher in patients with a clinical diagnosis of Fontan circulatory failure (mean 5.3 vs 7.4 m/sec, p = 0.003, Figure 2A). A cut-off value of 6.3 m/sec had a 90% sensitivity and 84% specificity to predict Fontan circulatory failure (AUC = 0.89; 95% CI [0.77 – 0.99], p = 0.001, Figure 2B). Conclusion Natural SW velocities after AVVC strongly correlated with parameters of Fontan circulatory failure. The preliminary results of this ongoing study highlight the potential of SW elastography in the assessment of patients with a Fontan circulation. Figure 1 Figure 2

The Value of Lacrimal Gland Ultrasonography and Shear Wave Elastography in the Evaluation of Primary Sjögren's Syndrome: A Cross-Sectional Study.

This study evaluates the effectiveness of lacrimal gland ultrasonography (LGUS) and shear wave elastography (SWE) in distinguishing primary Sjögren's syndrome (PSS) patients from healthy controls and examines their role in assessing disease activity and prognosis. A total of 35 PSS patients and 23 age- and gender-matched healthy controls were included. LGUS was used to grade lacrimal gland structure, while SWE assessed gland elasticity. Disease activity and prognosis were evaluated using european league against rheumatism sjögren's syndrome disease activity index (ESSDAI)and serologic markers. Compared with healthy controls, LGUS, Emean, and shear wave velocity (SWV) were significantly higher in PSS patients. The optimal cut-off value of LGUS for diagnosis of PSS was 2 (area under the curve [AUC]: 0.832, sensitivity: 80.0%, specificity: 69.6%), the optimal thresholds for diagnosis of PSS using Emean and SWV values are 9.4 kPa (AUC: 0.768, sensitivity: 65.7%, specificity: 82.6%) and 1.7 m/s (AUC: 0.823, sensitivity: 71.4%, specificity: 91.3%), respectively. There are statistical differences in Emean and SWV between subgroups based on european league against rheumatism sjögren's syndrome disease activity index (ESSDAI); there are statistical differences in LGUS, Emean, and SWV between subgroups based on IgG levels and complement titers. LGUS and SWE are accurate, noninvasive diagnostic tools for PSS and may serve as indicators of disease activity and prognosis.

Natural shear wave imaging outperforms conventional echocardiographic parameters in detecting elevated left ventricular filling pressures

Abstract Background Current conventional echocardiographic assessment of diastolic function relies on predicting left ventricular (LV) filling pressure as a surrogate of diastolic function. However, the current guidelines algorithm for estimation of LV filling pressures is complex. High frame rate (HFR) Shear wave (SW) imaging is emerging as a novel parameter for assessing myocardial stiffness, a key determinant of diastolic function. Natural SW can be induced, e.g., by mitral valve closure (MVC) and their propagation speed is directly related to myocardial stiffness. Little is known, however, to what extent SW after MVC can reflect diastolic LV filling pressures. Purpose We aimed at investigating the relationship between natural SW and LV diastolic filling pressures in comparison to conventional echocardiographic parameters. Methods Thirty patients (mean age 68.4±9.9 years) scheduled for clinically indicated left heart catheterization were prospectively recruited irrespective of diastolic function status. Conventional as well as HFR echocardiography (ca. 1200 frames/second) was performed immediately after the catheterization. We tracked SW occurring after MVC along the ventricular septum in the parasternal long axis view using an anatomical M-mode from base to apex colour coded for tissue acceleration. SW appeared immediately after as tilted green bands and their propagation velocity was measured semi-automatically (Figure 1). Results In our cohort, the LV mid-diastolic pressure (LVMDP) ranged from 5 to 19 mmHg, while the LV end-diastolic pressure (LVEDP) ranged from 7.5 to 29.5 mmHg. LV filling pressures were considered elevated if exceed 15 mmHg for LVMDP and 16 mmHg for LVEDP. Out of the conventional echocardiographic parameters, only mitral inflow to mitral relaxation velocity ratio (E/e’) correlated moderately with LV filling pressures (r=0.47, p=0.009 for LVMDP; and r=0.49, p=0.006 for LVEDP) (Figure 2 A,B). The accuracy of the conventional E/e’ cut-off value of 14 to predict elevated LV filling pressure is 76% for LVMDP and 70% for LVEDP (Figure 2C). SW velocities after MVC correlated strongly with diastolic LV pressures (r=0.65, p<0.001 for LVMDP; r=0.78, p<0.001 for LVEDP) (Figure 2 D,E). Interestingly, a cut-off value for SW velocity of 5.8 m/s showed an excellent ability to discriminate raised LVMDP (AUC: 0.93; sensitivity: 80%, specificity: 80%, accuracy: 80%) and elevated LVEDP (AUC: 0.96 ; Sensitivity: 89%, specificity: 95%, accuracy: 93%) (Figure 2F). Conclusions Our preliminary data showed that SW velocities at end-diastole are strongly related to LV filling pressures and can predict elevated LV filling pressures more accurately than conventional echocardiographic parameters. This ongoing study shows the potential of natural shear wave imaging as a promising innovative tool for assessment of diastolic function. Figure 1 Figure 2

Cardiac shear wave elastography: assessing the performance of different algorithms for shear wave speed estimation

Abstract Introduction Cardiac Shear Wave Elastography utilizes ultrafast echocardiographic imaging to assess myocardial stiffness through the propagation velocities of shear waves (SWs). Despite advancements, variability in SW speed measurements remains a challenge. Current assessment lacks a gold standard method and still relies on subjective visual assessment with manual measurements leading to inherent variability. Purpose Manual and nine semi-automatic algorithms for measuring SW speed were systematically tested, aiming to reduce variability and enhance reproducibility of the estimations. Methods High-frame-rate echocardiography images (1055±159 Hz) were acquired in parasternal long axis view. Anatomical M-modes were drawn along the septal wall. To visualize the SW, M-modes were color coded for tissue acceleration. SWs then appear as green bands, and their slopes correspond to tissue propagation velocity. SW slopes from healthy volunteers (n=67) and patients (n=53) with different cardiac conditions, covering a wide age range (19-89 years-old) were included to evaluate the performance of the methods in a clinical context. Measurements were performed manually and with 9 automatic methods: Time-frequency correlation (TFC), Regression window (RW), Radon Transform (RT), and 6 segmentation-based methods (e.g. maximum value). Automatic algorithms were initiated by indicating the position of SW by a mouse click. To assess reproducibility, this procedure was repeated 3 times for different sites along the SW. Failure of SW detection was counted to assess feasibility. Since the visualization of the SW’s and segmentation threshold depends on the selected color scale limits, 3 scales (0.5, 1, 2 m/s²) were tested (Figure 1). Finally, manual measurements served as reference, and agreement analysis was conducted. Results When accessing reproducibility across different starting points, only TFC exhibited variability (SD ±0.3 vs ±0.0 m/s for others). In terms of the color scale settings, RW and RT showed no variability (SD ±0.0 vs ± 0.3 m/s for manual), while Regression Weighted Maximum Value (RMW), emerged as the segmentation method with the least variability (SD ±0.1 m/s). RMW also showed highest feasibility [99%, (RW: 76% and RT: 90%)], correlation (r=0.77, r= 0.72, and r= 0.76 resp.), and agreement with a manual measurements (Figure 2). Conclusion Among the tested algorithms, Regression Weighted Maximum Value (RWM) demonstrated the highest feasibility, correlation and agreement with manual measurements. Our findings suggest this semi-automatic method provides an objective alternative to manual SW velocity estimations.

Integrated Geotechnical Analysis of Allophanic Volcanic Ash Soils: SDMT and Laboratory Perspectives

The geological study area is volcano-tectonic in nature. Microscopic observations and mineralogical analyses revealed the presence of allophane and diatom clusters whose mineral compositions coincided with weathered andesites and dacites. Edometric consolidation tests showed a high porosity and a reduction in the void ratio by up to five times. These are highly compressible soils with a Cc/Cs ratio of 12 to 15 and a specific gravity (Gs) of 2.4. Low initial bulk density (1.10 Mg/m³), high plasticity, and SUCS (OH) classification are typical of soft soils, with an effective friction angle (ɸ’CD) of 25.5° to 30° and effective cohesion (c’CD) of 11.90 to 47.27 KPa. The shear wave velocity for the first 10 m (Vs10) on average ranged from 78 m/s to 120 m/s, whereas that for the first 30 m (Vs30) was 169 m/s. The permeability, which was calculated indirectly, was between 2 × 10−7 and 3 × 10−8 m/s. With an organic matter content between 5% and 25%, the Caupicho soil is an organic mineral sediment that is not considered peat (non-peat). The results of this study serve as a basis for future analyses of soil dynamics, bearing capacity, and consolidation settlements in the medium and long term in an area of high urban growth in southern Quito, Ecuador.

Waveform tomography of the Antarctic Plate

Summary We present a new seismic shear wave velocity model of the upper mantle of the Antarctic Plate region, AP2024. It includes the lithosphere and underlying mantle down to 660 km depth beneath both the continental and oceanic portions of the plate. To augment the limited seismic station coverage of Antarctica, we assemble very large regional and global data sets, comprising all publicly available broadband seismic data. The model is built using 785 thousand seismograms from over 27 thousand events and 8.7 thousand stations. It is constrained by both body and Rayleigh surface waves, ensuring the dense data sampling of the entire upper mantle depth range. The tomographic inversion is global but focused on the Antarctic Plate, with the data sampling maximised in the Southern Hemisphere, with elaborate automated and manual outlier analysis and removal performed on the regional data, and with the regularisation tuned for the region. The upper mantle of the Antarctic continent exhibits a bimodal nature. The sharp boundary along the Transantarctic Mountains separates the cratonic eastern from tectonic western Antarctica and shows a shear-velocity contrast of up to 17% at ∼100 km depth. The bimodal pattern is also seen in the oceanic part of the plate, with the older oceanic lithosphere beneath the Indian sector of the Southern Ocean showing higher shear velocities. The continental lithosphere in East Antarctica shows high velocity anomalies similar to those beneath stable cratons elsewhere around the world. It is laterally heterogeneous and exhibits significant thinning in the near-coastal parts of Dronning Maud Land and Wilkes Land. A low velocity channel is observed along the southern front of the West Antarctic Rift System and is probably related to Cenozoic rifting. High seismic velocity anomalies are detected beneath the Antarctic Peninsula and are likely to indicate fragments of the recently subducted Phoenix Plate Slab. Low velocity anomalies beneath Marie Byrd Land extend into the deep upper mantle and are consistent with a deep mantle upwelling feeding West Antarctica intraplate magmatism.

Value of comprehensive evaluation of bladder structure and function in children by multi-modal ultrasound

To comprehensively evaluate the structure and function of the bladder wall in children using multi-modal ultrasound (MMU). A total of 110 children without urinary symptoms admitted to the First Affiliated Hospital of Zhengzhou University from January 2022 to June 2023 were included prospectively. MMU was performed and the vesical volume (VV), bladder wall thickness (BWT), shear wave velocity (SWV) of the anterior wall, resistance index (RI) and vascularization index (VI) were measured in the filled and emptied bladder respectively, and the ultrasound bladder compliance (UBC) was also calculated. The differences in MMU parameters in children among different bladder states, age groups and sexes and the correlation between age and different MMU parameters were analyzed. The age of 110 children was (6.4±3.5) years, of which 60 were boys (54.5%). The VV [127.00 (79.00, 219.50) vs 6.65 (5.10, 9.60) ml, P<0.001] and SWV [(2.25±0.36) vs (1.54±0.20) m/s, P<0.001] of filling condition were higher than that of emptying condition, while BWT [(2.52±0.25) vs (6.72±0.74) mm, P<0.001] and VI [(4.36±0.52)% vs (8.15±1.75) %, P<0.001] were lower than that of emptying condition. There were no significant differences in VV, BWT, SWV, RI, VI and UBC between boys and girls under either bladder emptying or filling conditions (all P>0.05). BWT in emptying condition, VV and BWT in filling condition all increased with age (r was 0.706, 0.891 and 0.298, respectively, and all P<0.05). MMU in children contributes to the comprehensive evaluation of bladder wall, and the influence of age and bladder filling state should be considered when evaluating MMU parameters.

Unveiling Cryosphere Dynamics by Distributed Acoustic Sensing and Data‐Driven Hydro‐Thermo Coupled Simulation

AbstractAs global warming continues, the Earth's cryosphere is experiencing severe degradation. This study leverages a novel combination of distributed acoustic sensing (DAS) and artificial intelligence to monitor and decipher cryospheric dynamics. We have developed an advanced time‐lapse surface wave analysis workflow to capture shear wave velocity changes during a 2‐month controlled permafrost thaw experiment in Fairbanks, Alaska. To understand the underlying physical mechanisms of , multimodal rock‐physics simulations were conducted to associate the observed to hydrological and thermal processes like heating and rainfall events. Furthermore, we employ a physics‐guided deep learning algorithm alongside interpretable techniques to evaluate the impact of various physical factors and shed light on the cryospheric hydro‐thermo coupling mechanisms. This study highlights the potential of using DAS and data‐driven rock‐physics simulation for complex cryosphere monitoring and offers a comprehensive view of the permafrost's thawing dynamics.

Relationship Between Muscle Tone and Elasticity: Simultaneous Quantitative Assessment Using Train-of-Four Monitoring and Continuous Shear Wave Elastography During Anesthesia Induction—A Prospective Observational Study

Background/Objectives: Non-invasive evaluations of muscle elasticity and tone are crucial in musculoskeletal medicine. Shear wave elastography (SWE) provides quantitative assessments of muscle elasticity, whereas train-of-four (TOF) monitoring measures muscle tone during neuromuscular blockades. This study investigated the relationship between muscle elasticity and tone during anesthesia induction using continuous SWE (C-SWE) and TOF monitoring. Methods: Fifteen patients who underwent general anesthesia with rocuronium were recruited. The muscle elasticity of the vastus lateralis was assessed using C-SWE, and muscle tone was evaluated using TOF monitoring. Measurements were taken at two time points: before rocuronium administration and during complete muscle relaxation, confirmed by the TOF ratio (TOF = 0). Statistical analyses were performed using paired t-tests and correlation analyses. Results: Data from 11 patients were analyzed. The mean shear wave velocity (SWV) decreased significantly from 5.0 ± 0.4 m/s before rocuronium administration to 3.1 ± 0.3 m/s during complete relaxation (p &lt; 0.0001). A significant negative correlation was observed between the baseline SWV and the degree of reduction in the SWV (r = −0.728, p = 0.011). No significant correlations were found between SWV and demographic factors such as age, sex, height, or body mass index. Conclusions: C-SWE and TOF monitoring are reliable and sensitive methods for evaluating muscle elasticity and tone during general anesthesia. This study highlights the interplay between muscle tone and elasticity, suggesting that muscles with a higher baseline tone exhibit a greater reduction in elasticity after relaxation. These findings have implications for improving intraoperative muscle function assessments and advancing the application of C-SWE in clinical practice.

The value of ultrasound measured rectus femoris thickness, cross-sectional area and shear wave velocity in assessment of muscle in postmenopausal women with osteosarcopenia.

To evaluate the value of ultrasound (US) and shear wave velocity (SWV) to assess muscle in postmenopausal women with osteosarcopenia (OSP). This study included 145 postmenopausal women, comprising 115 osteopenia/osteoporosis participants without sarcopenia (OP alone) and 30 OSP participants. All received the evaluation of bone mineral density (BMD), appendicular skeletal muscle mass index (ASMI), handgrip strength, calf circumference, 6-meter walking speed, and 5-time chair stand test. The cross-sectional area (RFcsa), thickness (RFthickness), and mean SWV of rectus femoris (RF) were measured by US and shear wave elastography. The clinical characteristics, RFcsa, RFthickness, and SWV, were compared between OP alone and OSP to determine the independent predictors of OSP. Receiver operating characteristic (ROC) curve analysis was used to evaluate the value of US and SWV for assessment of OSP. The RFcsa, RFthickness, SWV, and BMD of OSP were lower than those of OP alone (all P < 0.05). Through multivariate analysis, the diagnostic performance of the prediction model (area under the ROC curve, AUC, 0.917) composed of RFcsa and SWV was superior to RFcsa (AUC, 0.847), RFthickness (AUC, 0.797), and SWV (AUC, 0.740) alone. Moreover, the prediction model achieved 70.0% sensitivity, 93.0% specificity, and 88.3% accuracy. The RFcsa, RFthickness, and SWV have potential value in assessing muscle in OSP and can be applied to routine clinical management of postmenopausal women. US measured RF thickness, CSA and SWV could assist detection and clinical management of OSP in postmenopausal women.

Mapping site amplification with the dense recording of ambient vibration for the city of Lucerne (Switzerland): comparison between two approaches

Abstract Reliable site-specific amplification information can be retrieved using earthquake-based methods that involve the deployment of a permanent (or temporary) network of seismic recording stations. Such an endeavour may need to operate for years, especially within regions of high risk but low recurrence rates in seismic activity. Hence, time- and cost-effective approaches using ambient vibrations are gaining popularity. Among such techniques, the canonical correlation approach (CC) collates measured empirical amplification with its indicator computed from ambient vibrations (i.e. horizontal-to-vertical spectral ratios) for a training set of seismic stations, to predict site response at locations without earthquake recordings. Another method, the hybrid standard spectral ratio method (SSRh) takes advantage of simultaneous recordings of ambient vibrations that are adjusted using earthquake ground motion data using a limited number of instrumented sites to estimate local seismic soil response. We apply both methods in the Lucerne area (Switzerland), which is located on a soft sedimentary basin, and obtain consistent results that are comparable to amplification estimates derived solely from earthquake ground motion data. These results show significant linear amplification factors (8–10 or more) at the fundamental frequency of resonance of the sediments (0.8–2 Hz). However, both techniques show systematic differences in the spatial and frequency domains. The CC method tends to underestimate the amplification at the fundamental frequency, while the SSRh technique predicts higher amplification in the centre of the basin and lower amplification at the basin edges in comparison to the CC approach. The study discusses the impact of the limitations in the completeness of the calibration dataset, and variability introduced by the choice of the shear wave velocity model of the shallow subsurface and inelastic behaviour treatment for the CC method, as well as the influence of the measurement setup for the SSRh method.

Research on shale dynamic and static elastic modulus and anisotropy based on pressurization history

The dynamic and static elastic parameters of rocks exhibit differences. It is of great practical significance to carry out experiments on dynamic and static elastic parameters of rocks under reservoir conditions and determine the conversion relationship between dynamic and static elastic parameters. In this study, shale oil samples from the second member of Kongdong sag in Dagang Oilfield were analyzed by triaxial compression experiments at different bedding angles and longitudinal and shear wave velocity tests. Dynamic and static stiffness coefficient, elastic modulus and acoustic wave velocity change under different directions of pressure and pressure relief. The results indicate that the P-wave velocity, fast shear wave velocity, slow shear wave velocity, dynamic and static Young’s modulus exhibit an increase as the confining pressure rises, and the parameters are greater during the unloading process than during loading process. At identical confining pressures, the dynamic Young’s modulus measured by cores with parallel bedding plane is greater than that measured by cores with vertical bedding plane. The dynamic and static elastic mechanical parameters of different bedding angles can be transformed under varying pressures, and the dynamic elastic mechanical parameters measured under varying levels of confining pressure can be transformed into static elastic mechanical parameters under equivalent confining pressures, which offer fundamental parameters for examining rock mechanics properties and serving as a reference for developing fracturing construction plans for oil and gas reservoirs.

Geotechnical and Hydrogeological Zonation of Tailings Storage Facilities: Importance for Design, Construction, Operation, and Closure

This study introduces a conceptual model for understanding the hydromechanical behavior and zonation within tailings storage facilities (TSFs) constructed using the hydraulic backfill method, which constitutes over 98% of TSFs worldwide. The model identifies four distinct zones—dike, discharge, transition, and distal—each characterized by unique physical, geotechnical, and hydraulic properties. Key findings highlight gradients in parameters which systematically vary from the dam toward the settling pond. This study observes that seven parameters such as grain size, friction angle, shear strength, dry density, permeability, shear wave velocities, and liquefaction capacity decrease in value from the dike to the lagoon. Conversely, thirteen parameters such as fine content, porosity, cohesion, plasticity, degree of saturation, volumetric and gravimetric water content, capillary height, specific and volumetric surface of tailings, suction, air and water entry value in the soil water characteristic curve increase in value from the dike to the lagoon. These trends underscore the complex behavior of tailings and their implications for stability, drainage, and environmental impact. By integrating geological, geotechnical, hydrogeological, and geophysical data, this study provides a holistic framework for TSF management, addressing both current challenges and long-term environmental considerations.

Earthquake induced liquefaction hazard analysis for Chittagong City using machine learning

Liquefaction hazard analysis is crucial in earthquake-prone regions as it magnifies structural damage. In this study, standard penetration test (SPT) and shear wave velocity ( V s ) data of Chittagong City have been used to assess the liquefaction resistance of soils using artificial neural network (ANN). For a scenario of 7.5 magnitude (Mw) earthquake in Chittagong City, estimating the liquefaction-resistance involves utilizing peak horizontal ground acceleration (PGA) values of 0.15 and 0.28 g. Then, liquefaction potential index (LPI) is determined to assess the severity of liquefaction. In most boreholes, the LPI values are generally higher, with slightly elevated values in SPT data compared to V s data. The current study suggests that the Valley Alluvium, Beach and Dune Sand may experience extreme liquefaction with LPI values ranges from 9.55 to 55.03 and 0 to 37.17 for SPT and V s respectively, under a PGA of 0.15 g. Furthermore, LPI values ranges from 25.55 to 71.45 and 9.55 to 54.39 for SPT and V s correspondingly. The liquefaction hazard map can be utilized to protect public safety, infrastructure, and to create a more resilient Chittagong City.