WFUMB guidelines and recommendations for clinical use of ultrasound elastography: Part 3: liver

Prospective Evaluation of Various Ultrasound Parameters for Assessing Renal Allograft Rejection Subtypes: Elasticity and Dispersion as Diagnostic Tools

PURPOSE

Renal allograft rejection, either acute or chronic, is prevalent among many recipients. This study aimed to identify multiple Doppler ultrasound parameters for predicting renal allograft rejection.

MATERIALS AND METHODS

Between November 2021 and April 2022, 61 renal allograft recipients were studied prospectively after excluding two patients with dual transplants and seven with hydronephrosis. The analysis excluded 11 cases (10 due to missing Doppler data or pathology reports and one due to a high interquartile range/median dispersion value), resulting in a final analysis of 50 patients. Clinical characteristics, color Doppler imaging, superb microvascular imaging, and shear-wave imaging parameters were assessed by three experienced genitourinary radiologists. The Banff classification of the biopsy tissue served as the reference standard. Univariable and multivariable logistic regression, contingency matrices, and multiple machine-learning models were employed to estimate the associations.

RESULTS

Fifty kidney transplant recipients (mean age, 53.26±8.86 years; 29 men) were evaluated. Elasticity (≤14.8 kPa) demonstrated significant associations for predicting the combination of (borderline) T cell-mediated rejection (TCMR) categories (Banff categories 3 and 4) (p=0.006) and yielded equal or higher area under the receiver operating characteristics curve (AUC) values compared to various classifiers. Dispersion (>15.0 m/s/kHz) was the only significant factor for predicting the combination of non-TCMR categories (Banff categories 2, 5, and 6) (p=0.026) and showed equal or higher AUC values than multiple machine learning classifiers.

CONCLUSION

Elasticity (≤14.8 kPa) showed a significant association with the combination of (borderline) TCMR categories, whereas dispersion (>15.0 m/s/kHz) was significantly associated with the combination of non-TCMR categories in renal allografts.

Accuracy of Velacur in Assessing MASLD and MASH Patients Using Biopsy as the Gold Standard

Background/Objectives: VelacurTM is a novel, point-of-care ultrasound device developed to accurately diagnose patients with Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) and Metabolic Dysfunction-Associated Steatohepatitis (MASH). The Velacur system non-invasively assesses liver stiffness, attenuation, and the Velacurdetermined fat fraction (VDFF). In this study, the performance of Velacur was measured against biopsy results in a cohort of MASLD and MASH patients. Methods: This prospective study enrolled adult patients who were scheduled to undergo biopsy within 6 months of enrollment. The primary objective was to validate Velacur's findings against that of histological findings. The secondary objective was to compare Velacur results with those of FibroScan. Results: A total of 78 participants were enrolled, and 70 were included in the analysis. Patients had a mean age of 53.3 ± 13.1 years, with a mean BMI of 35.0 ± 6.24 kg/m2. A total of 11, 19, 13, 25, and 2 were characterized as F0 to F4, respectively. The mean Velacur stiffness was 6.48 ± 1.4 kPa, and the mean VDFF was 14.4 ± 5.1%. In patients with significant fibrosis the Velacur AUC [95% CI] was 0.86 [0.76, 0.93] and 0.79 [0.66, 0.88] for patients with advanced fibrosis. For measurements of steatosis, 2, 24, 20, and 24 patients were found to have S0 to S3, respectively. To determine moderate steatosis (≥S2), the VDFF had an AUC of 0.846 [0.716, 0.920]. In the comparison population (n = 59), VDFF (0.85 [0.72, 0.94]) was significantly different than FibroScan CAP (0.50 [0.35, 0.66]) for the detection of moderate steatosis. Conclusions: This study validates the use of Velacur as a non-invasive tool for assessment of steatosis and fibrosis, hallmarks of MASLD and MASH, when compared to histological evidence provided via hepatic biopsy. Further, Velacur outperformed FibroScan in the assessment of steatosis.

Towards linking histological changes to liver viscoelasticity: a hybrid analytical-computational micromechanics approach

Motivated by elastography that utilizes tissue mechanical properties as biomarkers for liver disease, with the eventual objective of quantitatively linking histopathology and bulk mechanical properties, we develop a micromechanical modeling approach to capture the effects of fat and collagen deposition in the liver. Specifically, we utilize computational homogenization to convert the microstructural changes in hepatic lobule to the effective viscoelastic modulus of the liver tissue, i.e. predict the bulk material properties by analyzing the deformation of repeating unit cell. The lipid and collagen deposition is simulated with the help of ad hoc algorithms informed by histological observations. Collagen deposition is directly included in the computational model, while composite material theory is used to convert fat content to the microscopic mechanical properties, which in turn is included in the computational model. The results illustrate the model's ability to capture the effect of both fat and collagen deposition on the viscoelastic moduli and represents a step towards linking histopathological changes in the liver to its bulk mechanical properties, which can eventually provide insights for accurate diagnosis with elastography.

Novel subharmonic-aided pressure estimation for identifying high-risk esophagogastric varices

BACKGROUND

Subharmonic-aided pressure estimation (SHAPE) is a technique for determining changes in ambient pressure. We aimed to analyze a novel SHAPE integrated into ultrasound diagnostic equipment to predict patients with liver cirrhosis at high risk of esophagogastric varices (EV).

METHODS

This prospective study included 111 patients with liver cirrhosis diagnosed between 2020 and 2023. We obtained liver stiffness measurements (LSM) and spleen stiffness measurements (SSM) using shear wave elastography and hepatic vein-portal vein (HV-PV) gradient using the SHAPE method. The EV risk was determined either as null, low, or high by esophagoscopy and Child-Pugh stage.

RESULTS

HV-PV gradient increased concordantly with the increase in EV risk (- 7.0 dB in null-risk, - 4.4 dB in low-risk, and - 2.0 dB in high-risk) with statistically significant difference among any two groups. The most appropriate cut-off value of the HV-PV gradient was - 3.5 dB, and sensitivity, specificity, and positive and negative predictive values were 80.0%, 89.0%, 80.0%, and 88.0%, respectively. The areas under the curve values for predicting the high-risk EV were 0.920, 0.843, and 0.824 for the HV-PV gradient, LSM, and SSM, respectively.

CONCLUSIONS

The novel SHAPE system demonstrated high accuracy in identifying patients with liver cirrhosis at a high risk of EV.

Comparison of Two-Dimensional Shear Wave Elastography Between Two Different Instruments for Hepatocellular Carcinoma Patients

OBJECTIVES

This study aimed to investigate and compare 2-dimensional shear wave elastography (2D-SWE) measurements and influencing factors among 2 different devices and to evaluate the ability and influencing factors of these measurements to assess liver fibrosis.

METHODS

From October 2022 to September 2023, 290 hepatocellular carcinoma (HCC) patients and 30 healthy volunteers were prospectively included. The 2D-SWE measurements were performed using AixPlorer V (SEmean) and APLIO i900 (CEmean). This study compared 2D-SWE measurements between instruments for evaluating the liver fibrosis stage and analyzed the potential influencing factors.

RESULTS

The 2D-SWE measurements obtained by the 2 instruments were significantly different (P < .001), but the differences were significant only for patients with stage F4 liver fibrosis (P < .001) and not for volunteers or patients with stage F0-F3 liver fibrosis (all P > .050). Multivariate linear regression analysis revealed that the factors independently influencing the SEmean were alanine aminotransferase (ALT) (P = .034) and liver fibrosis stage (P < .001), while fibrosis stage (P = .028) was the only factor influencing the CEmean.

CONCLUSIONS

Although 2D-SWE from the 2 different instruments was capable of detecting liver fibrosis, it yielded varying results in HCC patients. These discrepancies were predominantly observed in patients with F4 liver fibrosis but not in healthy adults or patients with F0-F3 liver fibrosis. One potential contributing factor to the differences between instruments could be ALT levels.

Role of multiparametric US in the preoperative assessment of hepatic parenchyma in patients with liver tumors

OBJECTIVES

The aim of this study was to evaluate the diagnostic performance of shear wave elastography (SWE), shear wave dispersion (SWD), and attenuation imaging (ATI) in assessment of hepatic parenchyma in patients with liver tumors before resection.

METHODS

Patients with liver tumors were prospectively enrolled in this study. All participants underwent SWE, SWD, and ATI examinations. Fibrosis stage, necroinflammatory activity and hepatic steatosis grade were determined histopathologically. We evaluated the stability of ATI, SWE and SWD examinations. Multivariable linear regression analyses were conducted to determine the determinant factors for SWE, SWD, attenuation coefficient (AC) values. A receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic performance of multiparametric US (ultrasond).

RESULTS

A total of 280 participants were enrolled in this study. TG (triglyceride) and steatosis for AC value were significant determinant factors. PLT (platelet), PT (prothrombin time), GGT (glutamyl transpeptidase), and fibrosis stage for SWE value were significant determinant factors. PLT, fibrosis stage and inflammation activity for SWD value were significant determinant factors. AC value was correlated with hepatic steatosis. Both SWE and SWD values were correlated with fibrosis stage, inflammation activity, respectively. The area under the ROC (AUROC) curve of ATI for predicting hepatic steatosis grade were 0.910(≥ S1), 0.927(≥ S2), 0.962(= S3), respectively. The AUROC curve of SWE for predicting fibrosis stage were 0.923(≥ S1), 0.934(≥ S2), 0.930(≥ S3), 0.895(= S4), respectively. The AUROC curve of SWD for predicting fibrosis stage were 0.858(≥ S1), 0.886(≥ S2), 0.866(≥ S1) (≥ S3), 0.825(= S4). The AUROC curve of SWE for predicting inflammation activity were 0.846(≥ G1), 0.724(≥ G2), 0.787 (≥ G3), respectively. The AUROC curve of SWD for predicting inflammation activity were 0.777(≥ G1), 0.727(≥ G2), 0.803 (≥ G3), respectively.

CONCLUSIONS

For patients with liver tumors, ATI technology showed excellent feasibility and diagnostic performance for detecting and grading hepatic steatosis, SWE was more accurate in detecting fibrosis stage than SWD, SWD was not superior to SWE in detecting inflammation activity.

Shear wave elastography primer for the abdominal radiologist

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Effects of hepatic fibrosis on the quantification of hepatic steatosis using the controlled attenuation parameter in patients with chronic hepatitis B

PURPOSE

This study assessed the impact of hepatic fibrosis on the diagnostic performance of the controlled attenuation parameter (CAP) in quantifying hepatic steatosis in patients with chronic hepatitis B (CHB).

METHODS

CHB patients who underwent liver stiffness measurement (LSM) and CAP assessment using transient elastography before liver resection between 2019 and 2022 were retrospectively evaluated. Clinical data included body mass index (BMI) and laboratory parameters. The histologically determined hepatic fat fraction (HFF) and fibrosis stages were reviewed by pathologists blinded to clinical and radiologic data. The Pearson correlation coefficient between CAP and HFF was calculated. The diagnostic performance of CAP for significant hepatic steatosis (HFF ≥10%) was assessed using areas under the receiver operating curve (AUCs), stratified by fibrosis stages (F0-1 vs. F2-4). Factors significantly associated with CAP were determined by univariable and multivariable linear regression analyses.

RESULTS

Among 399 CHB patients (median age 59 years; 306 men), 16.3% showed significant steatosis. HFF ranged from 0% to 60%. Of these patients, 9.8%, 19.8%, 29.3%, and 41.1% had fibrosis stages F0-1, F2, F3, and F4, respectively. CAP positively correlated with HFF (r=0.445, P<0.001). The AUC of CAP for diagnosing significant steatosis was 0.786 (95% confidence interval [CI], 0.726 to 0.845) overall, and significantly lower in F2-4 (0.772; 95% CI, 0.708 to 0.836) than in F0-1 (0.924; 95% CI, 0.835 to 1.000) (P=0.006). Multivariable analysis showed that BMI (P<0.001) and HFF (P<0.001) significantly affected CAP, whereas LSM and fibrosis stages did not.

CONCLUSION

CAP evaluations of significant hepatic steatosis are less reliable in CHB patients with significant or more advanced (F2-4) than with no or mild (F0-1) fibrosis.

Multiparametric Ultrasound for Chronic Liver Disease

Diffuse liver disease is a substantial world-wide problem. With the combination of conventional ultrasound of the abdomen, fat quantification and elastography, appropriate staging of the patient can be assessed. This information allows for the diagnosis of steatosis and detection of fibrosis as well as prognosis, surveillance, and prioritization for treatment. With the potential for reversibility with appropriate treatment accurate assessment for the stage of chronic liver disease is critical.

A Multi-Institutional Study on Ultrasound Image Analysis for Staging HBV-Derived Liver Fibrosis: A Potential Noninvasive Alternative to Liver Stiffness Measurement

INTRODUCTION

Liver stiffness measurement is principal for staging liver fibrosis but not included in routine examinations. We investigated whether comparable diagnostic performance can be achieved by mining ultrasound images and developing a novel serum index (NSI).

METHODS

Texture features were extracted from ultrasound images. Spearman correlation and logistics regression selected independent variables for significant (F ≥ 2) and advanced (F ≥ 3) fibrosis. We compared the diagnostic performance of transient elastography (TE), ultrasound image biomarker, conventional serum indices (aspartate aminotransferase-to-platelet ratio index, fibrosis-4 index, gamma-glutamyl transpeptidase-to-platelet ratio), and NSI in 365 patients with chronic hepatitis B.

RESULTS

Among patients, 52.1% had significant fibrosis and 24.2% had advanced fibrosis. PLT, gamma-glutamyl transferase, prealbumin, and globulin were incorporated into NSI. In the validation group, TE achieved the best performance (area under the curve [AUC]: 0.765 [0.690-0.849] for significant fibrosis; 0.812 [0.745-0.878] for advanced fibrosis), followed by ultrasound image biomarker (AUC: 0.712 [0.629-0.795]; 0.678 [0.595-0.763]) and NSI (AUC: 0.630 [0.534-0.725]; 0.659 [0.572-0.745]), outperforming conventional indices.

DISCUSSION

Texture analysis enhances ultrasound's diagnostic utility, but TE remains superior. When TE is unavailable, ultrasound image analysis and NSI, incorporating prealbumin, can serve as alternative tools for fibrosis staging.

Combi-Elastography versus Transient Elastography for Assessing the Histological Severity of Metabolic Dysfunction-Associated Steatotic Liver Disease

Background/Aims

Combi-elastography is a B-mode ultrasound-based method in which two elastography modalities are utilized simultaneously to assess metabolic dysfunction-associated steatotic liver disease (MASLD). However, the performance of combi-elastography for diagnosing metabolic dysfunction-associated steatohepatitis (MASH) and determining fibrosis severity is unclear. This study compared the diagnostic performances of combi-elastography and vibration-controlled transient elastography (VCTE) for identifying hepatic steatosis, fibrosis, and high-risk MASH.

Methods

Participants who underwent combi-elastography, VCTE, and liver biopsy were selected from a prospective cohort of patients with clinically suspected MASLD. Combi-elastography-related parameters were acquired, and their performances were evaluated using area under the receiver-operating characteristic curve (AUROC) analysis.

Results

A total of 212 participants were included. The diagnostic performance for hepatic steatosis of the attenuation coefficient adjusted by covariates from combi-elastography was comparable to that of the controlled attenuation parameter measured by VCTE (AUROC, 0.85 vs 0.85; p=0.925). The performance of the combi-elastography-derived fibrosis index adjusted by covariates for diagnosing significant fibrosis was comparable to that of liver stiffness measured by VCTE (AUROC, 0.77 vs 0.80; p=0.573). The activity index from combi-elastography adjusted by covariates was equivalent to the FibroScan-aspartate aminotransferase score in diagnosing high-risk MASH among participants with MASLD (AUROC, 0.72 vs 0.74; p=0.792).

Conclusions

The performance of combi-elastography is similar to that of VCTE when evaluating histology of MASLD.

Elastographic Assessment of Atherosclerotic Plaques and Determination of Vascular Risk in Patients with Rheumatoid Arthritis

Objectives: The present study aimed to examine the role of two-dimensional shear wave elastography (SWE) in the assessment of the vascular wall of the carotid arteries and atherosclerotic plaques in patients with rheumatoid arthritis with moderate and low disease activity versus healthy controls. Methods: An observational case-control study was carried out at the University Medical Hospital "Kaspela" in Plovdiv, Bulgaria, from June 2023 to August 2024. This study included 24 patients with rheumatoid arthritis (RA) and 25 healthy controls. We employed two-dimensional SWE (2D-SWE) to examine the vessels around the plaques. The potential links with the degree of stenosis, plaque type, and cardiovascular risk were analyzed. Results: In the RA group, the 2D-SWE values showed significant positive correlations with the severity of the atherosclerotic plaques (rs = 0.461; 95% CI: 0.049 to 0.739; p = 0.023) and the degree of stenosis (rs = 0.920; 95% CI: 0.793 to 0.970; p < 0.001). Based on 2D-SWE, a ROC curve analysis distinguished higher severity plaques from lower severity plaques with an AUC = 0.818, 95% CI: 0.683 to 0.913. The optimal cut-off value of 2D-SWE > 32.40 kPa was associated with a sensitivity of 96%, a specificity of 56%, a positive predictive value (PPV) of 66.70%, and a negative predictive value (NPV) of 92.90%. Conclusion: Elastography can be an effective technique for assessing and stratifying atherosclerotic plaques in patients with RA, as well as for aiding in the early detection and subsequent prevention of future complications.

Effect of maneuvers, diuresis, and fluid administration on ultrasound-measured liver stiffness after Fontan

BACKGROUND

To determine the effect of stress maneuvers/interventions on ultrasound liver stiffness measurements (LSMs) in patients with Fontan circulation and healthy controls.

METHODS

In this prospective, IRB-approved study of 10 patients after Fontan palliation and 10 healthy controls, ultrasound 2D shear-wave elastography LSMs were acquired at baseline and after maximum inspiration, expiration, standing, handgrip, aerobic exercise, i.v. fluid (500 mL normal saline) administration, and i.v. furosemide (20 mg) administration. Absolute and percent change in LSM were compared between baseline and each maneuver, and then from fluid infusion to after diuresis.

RESULTS

Median ages were 25.5 and 26 years in the post-Fontan and control groups (p = 0.796). LSMs after Fontan were higher at baseline (2.6 vs. 1.3 m/s) and with all maneuvers compared to controls (all p < 0.001). Changes in LSM with maneuvers, exercise, fluid, or diuresis were not significant when compared to baseline in post-Fontan patients. LSM in controls increased with inspiration (+0.02 m/s, 1.6%, p = 0.03), standing (+0.07 m/s, 5.5%, p = 0.03), and fluid administration (+0.10 m/s, 7.8%, p = 0.002), and decreased 60 minutes after diuretic administration (-0.05 m/s, -3.9%, p = 0.01) compared to baseline. LSM after diuretic administration significantly decreased when compared to after i.v. fluid administration at 30 minutes (-0.79 m/s, -26.5%, p = 0.004) and 60 minutes (-0.78 m/s, -26.2%, p = 0.017) for patients after Fontan and controls at 15 minutes (-0.12 m/s, -8.70%, p = 0.002), 30 minutes (-0.15 m/s, -10.9%, p = 0.003), and 60 minutes (-0.1 m/s, -10.9%, p = 0.005).

CONCLUSIONS

LSM after Fontan is higher with more variability compared to controls. Diuresis is associated with significantly decreased liver stiffness in both patients after Fontan and controls, with the suggestion of a greater effect in Fontan patients.

Diagnostic performance of shear wave measurement in the detection of hepatic fibrosis: A multicenter prospective study

AIM

This study aimed to establish the shear wave measurement (SWM) cut-off value for each fibrosis stage using magnetic resonance (MR) elastography values as a reference standard.

METHODS

We prospectively analyzed 594 patients with chronic liver disease who underwent SWM and MR elastography. Correlation coefficients (were analyzed, and the diagnostic value was evaluated by the area under the receiver operating characteristic curve. Liver stiffness was categorized by MR elastography as F0 (<2.61 kPa), F1 (≥2.61 kPa, <2.97 kPa, any fibrosis), F2 (≥2.97 kPa, <3.62 kPa, significant fibrosis), F3 (≥3.62 kPa, <4.62 kPa, advanced fibrosis), or F4 (≥4.62 kPa, cirrhosis).

RESULTS

The median SWM values increased significantly with increasing fibrosis stage (p < 0.001). The correlation coefficient between SWM and MR elastography values was 0.793 (95% confidence interval 0.761-0.821). The correlation coefficients between SWM and MR elastography values significantly decreased with increasing body mass index and skin-capsular distance; skin-capsular distance values were associated with significant differences in sensitivity, specificity, accuracy, or positive predictive value, whereas body mass index values were not. The best cut-off values for any fibrosis, significant fibrosis, advanced fibrosis, and cirrhosis were 6.18, 7.09, 8.05, and 10.89 kPa, respectively.

CONCLUSIONS

This multicenter study in a large number of patients established SWM cut-off values for different degrees of fibrosis in chronic liver diseases using MR elastography as a reference standard. It is expected that these cut-off values will be applied to liver diseases in the future.

Liver and spleen shear-wave elastography in the diagnosis and severity staging of myeloproliferative diseases and myelofibrosis

AIMS

Spleen and liver stiffness, investigated by VCTE (Vibration-Controlled Transient Elastography), have been associated with marrow fibrosis in patients with myeloproliferative neoplasms (MPNs). Tissue stiffness can be assessed by shear wave point (pSWE) and bidimensional elastography (2DSWE). Spleen stiffness (SS) values were higher in Myelofibrosis (MF) and Polycythemia Vera (PV) compared to Essential Thrombocythemia (ET). We aimed to identify SWE differences between MPN patients and healthy volunteers; to evaluate specific SWE features in patients with MF, PV and ET; to establish a correlation with bone marrow fibrosis in patients with myeloproliferative disease.

METHODS

Patients with myeloproliferative disease and healthy volunteers performed evaluation of spleen and liver stiffness (LS) by pSWE and 2DSWE.

RESULTS

A total of 218 subjects were included: 143 with myeloproliferative disease (64 MF, 29.4%, 33 PV, 15.1% and 46 ET, 21.1%), and 75 (34.4%) healthy volunteers. Compared to volunteers, MF patients had greater spleen (pSWE 40.9 vs. 26.3 kPa, p < 0.001; 2DSWE 34.9 vs. 20.1 kPa, p < 0.001), and liver stiffness (pSWE 7.72 vs. 5.52 kPa, p < 0.001; 2DSWE 6.96 vs. 5.01 kPa, p < 0.001). In low (0-1) (n = 81, 60.4%) versus high-grade bone marrow fibrosis (2-3) (n = 42, 39.6%), is evident a higher median stiffness in patients with higher grades of fibrosis both for liver (pSWE 5.2 vs. 6.65 kPa; 2DSWE 5.1 vs. 6.05 kPa) and spleen (pSWE 27.2 vs. 37.9 kPa, 2DSWE 21.7 vs 30.75 kPa-p < 0.001 in both).

CONCLUSION

SWE evaluation distinguishes MF patients from HV and ET/PV and may help in MPN diagnosis. LS and SS values are associated with bone marrow fibrosis grade.

Head-to-Head Comparison of Hepatic Vein and Superior Vena Cava Flow Velocity Waveform Analyses for Predicting Elevated Right Atrial Pressure

OBJECTIVE

Blood flow in the hepatic veins and superior vena cava (SVC) reflects right heart filling; however, their Doppler profiles are often not identical, and no studies have compared their diagnostic efficacies. We aimed to determine which venous Doppler profile is reliable for detecting elevated right atrial pressure (RAP).

METHODS

In 193 patients with cardiovascular diseases who underwent cardiac catheterization within 2 d of echocardiography, the hepatic vein systolic filling fraction (HV-SFF) and the ratio of the peak systolic to diastolic forward velocities of the SVC (SVC-S/D) were measured. HV-SFF < 55% and SVC-S/D < 1.9 were regarded as elevated RAP. We also calculated the fibrosis 4 index (FIB-4) as a serum liver fibrosis marker.

RESULTS

HV-SFF and SVC-S/D were feasible in 177 (92%) and 173 (90%) patients, respectively. In the 161 patients in whom both venous Doppler waveforms could be measured, HV-SFF and SVC-S/D were inversely correlated with RAP (r = -0.350, p < 0.001; r = -0.430, p < 0.001, respectively). SVC-S/D > 1.9 showed a significantly higher diagnostic accuracy of RAP elevation compared with HV-SFF < 55% (area under the curve, 0.842 vs. 0.614, p < 0.001). Multivariate analyses showed that both FIB-4 (β = -0.211, p = 0.013) and mean RAP (β = -0.319, p < 0.001) were independent determinants of HV-SFF. In contrast, not FIB-4 but mean RAP (β = -0.471, p < 0.001) was an independent determinant of SVC-S/D. The diagnostic accuracy remained unchanged when HV-SFF < 55% was considered in conjunction with the estimated RAP based on the inferior vena cava morphology. Conversely, SVC-S/D showed an incremental diagnostic value over the estimated RAP.

CONCLUSIONS

SVC-S/D enabled a more accurate diagnosis of RAP elevation than HV-SFF.

Characterizing dispersion in bovine liver using ARFI-based shear wave rheometry

Background:Dispersion presents both a challenge and a diagnostic opportunity in shear wave elastography (SWE).Shear Wave Rheometry(SWR) is an inversion technique for processing SWE data acquired using an acoustic radiation force impulse (ARFI) excitation. The main advantage of SWR is that it can characterize the shear properties of homogeneous soft media over a wide frequency range. Assumptions associated with SWR include tissue homogeneity, tissue isotropy, and axisymmetry of the ARFI excitation).Objective:Evaluate the validity of the SWR assumptions in ex vivo bovine liver.Approach:SWR was used to measure the shear properties of bovine liver tissue as function of frequency over a large frequency range. Assumptions associated with SWR (tissue homogeneity, tissue isotropy, and axisymmetry of the ARFI excitation) were evaluated through measurements performed at multiple locations and probe orientations. Measurements focused on quantities that would reveal violations of the assumptions.Main results:Measurements of shear properties were obtained over the 25-250 Hz range, and showed a 4-fold increase in shear storage modulus (from 1 to 4 kPa) and over a 10-fold increase in the loss modulus (from 0.2 to 3 kPa) over that decade-wide frequency range. Measurements under different conditions were highly repeatable, and model error was low in all cases.Significance and Conclusion:SWR depends on modeling the ARFI-induced shear wave as a full vector viscoelastic shear wave resulting from an axisymmetric source; it is agnostic to any specific rheological model. Despite this generality, the model makes three main simplifying assumptions. These results show that the modeling assumptions used in SWR are valid in bovine liver over a wide frequency band.

Adaptation of Clinical Practice Guideline for Assessment of Liver Fibrosis in Patients with Non Alcoholic Fatty Liver Disease in Isfahan Province

Non-alcoholic fatty liver disease (NAFLD) refers to the presence of hepatic steatosis (accumulation of fat in the liver to over 5% of its weight) in the absence of secondary causes of fat accumulation in the liver such as excessive alcohol use. NAFLD is divided into two types: non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH). Therefore, in this clinical guideline, we sought to determine general and important policies for this disease and modify its managment approaches. We adapted this guideline for the management of NAFLD in Isfahan Province. This guideline was developed by clinical appraisal and review of the evidence, available clinical guidelines, and in consultation with members of the Isfahan Chamber of the Iranian Association of Gastroenterology and Hepatology. Biopsy is recommended as the most reliable method (gold standard) to diagnose steatohepatitis and fibrosis in patients with NAFLD. NAFLD fibrosis score (NFS) and fibrosis-4 (FIB-4) are recommended as the test with the highest predictive value for advanced fibrosis in patients with NAFLD compared to other serologic tests. Among the noninvasive methods used to assess liver fibrosis, transient elastography (TE) is preferable to other methods.

An Optimization Approach for Creating Application-specific Ultrasound Speckle Tracking Algorithms

OBJECTIVE

Ultrasound speckle tracking enables in vivo measurement of soft tissue deformation or strain, providing a non-invasive diagnostic tool to quantify tissue health. However, adoption into new fields is challenging since algorithms need to be tuned with gold-standard reference data that are expensive or impractical to acquire. Here, we present a novel optimization approach that only requires repeated measurements, which can be acquired for new applications where reference data might not be readily available or difficult to get hold of.

METHODS

Soft tissue motion was captured using ultrasound for the medial collateral ligament (MCL) of three quasi-statically loaded porcine stifle joints, and medial ligamentous structures of a dynamically loaded human cadaveric knee joint. Using a training subset, custom speckle tracking algorithms were created for the porcine and human ligaments using surrogate optimization, which aimed to maximize repeatability by minimizing the normalized standard deviation of calculated strain maps for repeat measurements. An unseen test subset was then used to validate the tuned algorithms by comparing the ultrasound strains to digital image correlation (DIC) surface strains (porcine specimens) and length change values of the optically tracked ligament attachments (human specimens).

RESULTS

After 1500 iterations, the optimization routine based on the porcine and human training data converged to similar values of normalized standard deviations of repeat strain maps (porcine: 0.19, human: 0.26). Ultrasound strains calculated for the independent test sets using the tuned algorithms closely matched the DIC measurements for the porcine quasi-static measurements (R > 0.99, RMSE < 0.59%) and the length change between the tracked ligament attachments for the dynamic human dataset (RMSE < 6.28%). Furthermore, strains in the medial ligamentous structures of the human specimen during flexion showed a strong correlation with anterior/posterior position on the ligaments (R > 0.91).

CONCLUSION

Adjusting ultrasound speckle tracking algorithms using an optimization routine based on repeatability led to robust and reliable results with low RMSE for the medial ligamentous structures of the knee. This tool may be equally beneficial in other soft-tissue displacement or strain measurement applications and can assist in the development of novel ultrasonic diagnostic tools to assess soft tissue biomechanics.

Evaluation of the Mechanical Behavior of the Patellar and Semitendinosus Tendons Using Supersonic Shear-wave Imaging (SSI) Elastography and Tensile Tests

Objective  To analyze the mechanical properties of the patellar (PT) and semitendinosus (ST) tendons from fresh-frozen human cadavers from a tissue bank using supersonic shear-wave imaging (SSI) elastography and tensile tests. Methods  We tested seven PT and five ST samples on a traction machine and performed their simultaneous assessment through SSI. The measurements enabled the comparison of the mechanical behavior of the tendons using the stress x strain curve and shear modulus (μ) at rest. In addition, we analyzed the stress x μ relationship under tension and tested the relationship between these parameters. The statistical analysis of the results used unpaired t -tests with Welch correction, the Pearson correlation, and linear regression for the Young modulus (E) estimation. Results  The μ values for the PT and ST at rest were of 58.86 ± 5.226 kPa and 124.3 ± 7.231 kPa respectively, and this difference was statistically significant. The correlation coefficient between stress and μ for the PT and ST was very strong. The calculated E for the PT and ST was of 19.97 kPa and 124.8 kPa respectively, with a statistically significant difference. Conclusion  The ST was stiffer than the PT in the traction tests and SSI evaluations. The μ value was directly related to the stress imposed on the tendon. Clinical relevance  The present is an evaluation of the mechanical properties of the tendons most used as grafts in knee ligament reconstruction surgeries.

Assessment of the liver with two-dimensional shear wave elastography following COVID-19 infection: A pilot study

Introduction/Purpose

The coronavirus disease (COVID-19) is a widely spread viral infectious disease, which can impact multiple organs, including the liver. Elevated liver enzymes have been reported in COVID-19 patients; however, potential changes in liver stiffness following the viral infection remain uncertain. The main aim of this pilot study was to determine if there is a significant difference in liver stiffness between individuals who have never been infected with COVID-19 and those who had been infected with COVID-19 <6 months, experiencing only mild symptoms. The secondary aim was to compare the liver stiffness between participants infected with COVID-19 depending on the elapsed time since infection.

Methods

Two-dimensional shear wave elastography (2D-SWE) was performed prospectively on 68 participants. Thirty-four participants had been infected with COVID-19 (all for <6 months) (COVID-19 group), and another 34 had never been infected with COVID-19 (control group). The mean 2D-SWE measurements of both the COVID-19 group and the control group were compared using an independent t-test. The mean 2D-SWE measurements of the COVID-19 subgroups A (<2 months), B (2 to <4 months) and C (4 to <6 months) were compared using a one-way ANOVA test (P < 0.05).

Results

The (mean ± standard deviation) liver stiffness (kPa) of the COVID-19 group (5.26 ± 1.63 kPa) was significantly higher than the control group (4.30 ± 0.96 kPa) (P = 0.005). There was no significant difference in liver stiffness among subgroups A (5.20 ± 1.79 kPa), B (4.70 ± 1.53 kPa) and C (5.96 ± 1.48 kPa) (P = 0.143) respectively.

Discussion

The mean liver stiffness of 4.30  ±  0.96k Pa in the control group showed a high probability of being normal as per guidelines. Conversely, the mean liver stiffness of 5.26  ±  1.63 kPa in the COVID-19 group exhibited a statistically significant increase compared to the control group. However, compensated advanced chronic liver disease was ruled out without other known clinical signs, as per guidelines.

Conclusion

A statistically significant increase in liver stiffness value was observed in the post-COVID-19 infection group compared to the group who had never been infected. This highlights the potential for short-term impact on liver stiffness associated with COVID-19 infection. However, it is unclear if these changes in liver stiffness are associated with liver injury. Further study is warranted to investigate the effects of COVID-19 infection and its long-term impact on the liver.

Shear wave trajectory detection in ultra-fast M-mode images for liver fibrosis assessment: A deep learning-based line detection approach

Stiffness measurement using shear wave propagation velocity has been the most common non-invasive method for liver fibrosis assessment. The velocity is captured through a trace recorded by transient ultrasonographic elastography, with the slope indicating the velocity of the wave. However, due to various factors such as noise and shear wave attenuation, detecting shear wave trajectory on wave propagation maps is a challenging task. In this work, we made the first attempt to use deep learning methods for shear wave trajectory detection on wave propagation maps. Specifically, we adopted five deep learning models in this task and evaluated them by using a well-acknowledged metric based on EA-Angular-Score (EAA) and task-specific metric based on Young s-Score (Ys) in the line-detection field. Furthermore, we proposed an end-to-end framework based on a Transformer and Hough transform, named Transformer-enhanced Hough Transform (TEHT). It took a wave propagation map as input image and directly output the slope of the shear wave trajectory. The framework extracts multi-scale local features from wave propagation maps, employs a deformable attention mechanism for feature fusion, identifies the target line using the Hough transform's voting mechanism, and calculates the contribution of each scale through channel attention. Wave propagation maps from 68 patients were utilized in this study, with manual annotation performed by a rater who was trained as a radiologist, serving as the reference value. The evaluation revealed that the SLNet model exhibited F-measure of EA and Ys values as 40.33 % and 40.72 %, respectively, while the TEHT model showed F-measure of EA and Ys values as 80.96 % and 98.00 %, respectively. TEHT yielded significantly better performance than other deep learning models. Moreover, TEHT demonstrated strong concordance with the gold standard, yielding R2 values of 0.967 and 0.968 for velocity and liver stiffness, respectively. The present study therefore suggests the application of the TEHT model for assessing liver fibrosis owing to its superiority among the five deep learning models.

Simultaneous grading diagnosis of liver fibrosis, inflammation, and steatosis using multimodal quantitative ultrasound and artificial intelligence framework

Noninvasive, accurate, and simultaneous grading of liver fibrosis, inflammation, and steatosis is valuable for reversing the progression and improving the prognosis quality of chronic liver diseases (CLDs). In this study, we established an artificial intelligence framework for simultaneous grading diagnosis of these three pathological types through fusing multimodal tissue characterization parameters dug by quantitative ultrasound methods derived from ultrasound radiofrequency signals, B-mode images, shear wave elastography images, and clinical ultrasound systems, using the liver biopsy results as the classification criteria. One hundred forty-two patients diagnosed with CLD were enrolled in this study. The results show that for the classification of fibrosis grade ≥ F1, ≥ F2, ≥ F3, and F4, the highest AUCs were respectively 0.69, 0.82, 0.84, and 0.88 with single clinical indicator alone, and were 0.81, 0.83, 0.89, and 0.91 with the proposed method. For the classification of inflammation grade ≥ A2 and A3, the highest AUCs were respectively 0.66 and 0.76 with single clinical indicator alone and were 0.80 and 0.93 with the proposed method. For the classification of steatosis grade ≥ S1 and ≥ S2, the highest AUCs were respectively 0.71 and 0.90 with single clinical indicator alone and were 0.75 and 0.92 with the proposed method. The proposed method can effectively improve the grading diagnosis performance compared with the present clinical indicators and has potential applications for noninvasive, accurate, and simultaneous diagnosis of CLDs.

Viscoelasticity in 3D Cell Culture and Regenerative Medicine: Measurement Techniques and Biological Relevance

The field of mechanobiology is gaining prominence due to recent findings that show cells sense and respond to the mechanical properties of their environment through a process called mechanotransduction. The mechanical properties of cells, cell organelles, and the extracellular matrix are understood to be viscoelastic. Various technologies have been researched and developed for measuring the viscoelasticity of biological materials, which may provide insight into both the cellular mechanisms and the biological functions of mechanotransduction. Here, we explain the concept of viscoelasticity and introduce the major techniques that have been used to measure the viscoelasticity of various soft materials in different length- and timescale frames. The topology of the material undergoing testing, the geometry of the probe, the magnitude of the exerted stress, and the resulting deformation should be carefully considered to choose a proper technique for each application. Lastly, we discuss several applications of viscoelasticity in 3D cell culture and tissue models for regenerative medicine, including organoids, organ-on-a-chip systems, engineered tissue constructs, and tunable viscoelastic hydrogels for 3D bioprinting and cell-based therapies.

The evaluation of non-alcoholic fatty liver disease in children with obesity with vibration-controlled transient elastography

INTRODUCTION

Parallel to the worldwide increase in obesity, the epidemic of chronic liver disease is increasing also in pediatric population. Our aim is to provide a different outlook on the current screening confusion in pediatric non-alcoholic fatty liver disease (NAFLD) with the non-invasive vibration-controlled transient elastography (VCTE) method.

MATERIALS AND METHODS

This single-center, cross-sectional, comparative study was performed at the tertiary center, included 95 patients with obesity and 116 controls, both groups were 9-18 years of ages. VCTE examinations performed in all patients. The cut-off values for controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) were established by comparing the study and control groups.

RESULTS

The cut-off for CAP was determined as >236 dB/m when comparing the two groups. The AUC was 0.900 (95% CI, 0.851-0.937) and the diagnostic accuracy was 77.9% and 91.4% for sensitivity and specificity, respectively. The cut-off value for LSM >5 kPa was determined by comparison of the two groups. The AUC was 0.794 (95% CI, 0.733-0.846) and the diagnostic accuracies were 50.5% and 90.5% for sensitivity and specificity, respectively.

CONCLUSIONS

There is no benchmark method for screening pediatric NAFLD. However, VCTE is a promising method for screening pediatric NAFLD. It is accessible, repeatable and practical.

Metabolic-Dysfunction-Associated Steatotic Liver Disease (MASLD) after Liver Transplantation: A Narrative Review of an Emerging Issue

The development of steatotic liver disease after liver transplant (LT) is widely described, and epidemiological data have revealed an increased incidence in recent times. Its evolution runs from simple steatosis to steatohepatitis and, in a small proportion of patients, to significant fibrosis and cirrhosis. Apparently, post-LT steatotic disease has no impact on the recipient's overall survival; however, a higher cardiovascular and malignancy burden has been reported. Many donors' and recipients' risk factors have been associated with this occurrence, although the recipient-related ones seem of greater impact. Particularly, pre- and post-LT metabolic alterations are strictly associated with steatotic graft disease, sharing common pathophysiologic mechanisms that converge on insulin resistance. Other relevant risk factors include genetic variants, sex, age, baseline liver diseases, and immunosuppressive drugs. Diagnostic evaluation relies on liver biopsy, although non-invasive methods are being increasingly used to detect and monitor both steatosis and fibrosis stages. Management requires a multifaceted approach focusing on lifestyle modifications, the optimization of immunosuppressive therapy, and the management of metabolic complications. This review aims to synthesize the current knowledge of post-LT steatotic liver disease, focusing on the recent definition of metabolic-dysfunction-associated steatotic liver disease (MASLD) and its metabolic and multisystemic concerns.

Shear wave elastography to assess stiffness of the human ovary and other reproductive tissues across the reproductive lifespan in health and disease†

The ovary is one of the first organs to show overt signs of aging in the human body, and ovarian aging is associated with a loss of gamete quality and quantity. The age-dependent decline in ovarian function contributes to infertility and an altered endocrine milieu, which has ramifications for overall health. The aging ovarian microenvironment becomes fibro-inflammatory and stiff with age, and this has implications for ovarian physiology and pathology, including follicle growth, gamete quality, ovulation dynamics, and ovarian cancer. Thus, developing a non-invasive tool to measure and monitor the stiffness of the human ovary would represent a major advance for female reproductive health and longevity. Shear wave elastography is a quantitative ultrasound imaging method for evaluation of soft tissue stiffness. Shear wave elastography has been used clinically in assessment of liver fibrosis and characterization of tendinopathies and various neoplasms in thyroid, breast, prostate, and lymph nodes as a non-invasive diagnostic and prognostic tool. In this study, we review the underlying principles of shear wave elastography and its current clinical uses outside the reproductive tract as well as its successful application of shear wave elastography to reproductive tissues, including the uterus and cervix. We also describe an emerging use of this technology in evaluation of human ovarian stiffness via transvaginal ultrasound. Establishing ovarian stiffness as a clinical biomarker of ovarian aging may have implications for predicting the ovarian reserve and outcomes of Assisted Reproductive Technologies as well as for the assessment of the efficacy of emerging therapeutics to extend reproductive longevity. This parameter may also have broad relevance in other conditions where ovarian stiffness and fibrosis may be implicated, such as polycystic ovarian syndrome, late off target effects of chemotherapy and radiation, premature ovarian insufficiency, conditions of differences of sexual development, and ovarian cancer. Summary sentence:  Shear Wave Elastography is a non-invasive technique to study human tissue stiffness, and here we review its clinical applications and implications for reproductive health and disease.

Image-guided point-shear-wave elastography: a valid and reliable technique for liver fibrotic staging

PURPOSE

Despite progressive implementation of image-guided point-shear wave elastography (pSWE) in guidelines as an alternative to transient elastography for the staging of fibrotic liver disease, pSWE is not widely adopted in clinical workflow. More information on reliability and validity of pSWE systems is needed. Therefore, we performed a phantom study to evaluate the validity and reliability of pSWE with ultrasound systems.

METHODS

Validity and reliability of pSWE measurements from three ultrasound systems were evaluated. Measurements were performed on an elasticity phantom with reference elasticities of 7 ± 1 (low) (median ± interquartile range (IQR)), 14 ± 2 (medium) and 26 ± 3 (high) kPa. Measurements were repeated in tenfold for each reference at 2, 3 and 4 cm depth. Results were considered valid when median elasticity ± IQR was between the uncertainty limits (IQR) for each reference elasticity value and reliable when IQR/median < 0.30.

RESULTS

pSWE with the systems provided valid results for all reference elasticities and focal depths, except for overestimation of high reference elasticity at 2 and 4 cm depth for one system (41.5 ± 4.3 and 39.0 ± 1.2 kPa, respectively). Measurements were reliable with a maximum IQR/median of 0.13, well below the guideline of IQR/median < 0.30.

DISCUSSION

The results support the use of pSWE as an alternative to invasive or non-image guided noninvasive techniques for liver fibrotic staging.

CONCLUSIONS

pSWE with ultrasound systems from different vendors is valid and reliable and can therefore be implemented to optimize clinical workflow by performing imaging and elastography simultaneously.

A comparative study of three ultrasound techniques for liver fibrosis staging

The aim of this study is to assess the agreement and performance of visual transient elastography (ViTE), sound touch elastography (STE), and sound touch quantification (STQ) for liver fibrosis staging using transient elastography (TE) as a standard. We finally enrolled 252 subjects with chronic liver disease (CLD) who underwent ViTE, STE, STQ, and TE examinations simultaneously in our hospital from October 2022 to July 2023. We evaluated the correlation and agreement between various technologies. And also evaluated the performances and optimal cutoffs of ViTE, STE, and STQ . The correlation coefficients of ViTE and TE, STE and TE, STQ and TE were 0.863, 0.709, and 0.727, respectively. The ICC among ViTE, STE, STQ, and TE was 0.911. The area under the receiver operating characteristics (AUROCs) of ViTE, STE, and STQ for detection of TE of ≥5 kPa, ≥10 kPa, ≥15 kPa, and ≥20 kPa were 0.867, 0.771, 0.804; 0.972, 0.935, 0.933; 0.998, 0.973, 0.968; and 1.000, 0.960, 0.954, respectively. The AUROCs of ViTE for detection of lower stages (TE≥5 kPa and ≥10 kPa) were significantly higher than STE and STQ in the overall cohort (ViTE vs. STE: Z  = 2.766, for TE ≥5 kPa; ViTE vs. STE: Z  = 2.145, ; ViTE vs. STQ: Z  = 2.587, for TE ≥10 kPa) (all P < 0.05). These methods all have coincided with performance in more advanced stages (TE ≥15 kPa and ≥20 kPa) (all P  > 0.05). These methods showed excellent correlation and agreement. ViTE performance in more advanced fibrosis differentiation is comparable to the STE and STQ while ViTE is more accurate than STE and STQ to identify patients with mild CLD stage, and can more effectively rule out compensated advanced CLD.

Validation of Baveno VII criteria for clinically significant portal hypertension by two-dimensional shear wave elastography

BACKGROUND

The Baveno VII consensus proposed criteria for the non-invasively diagnosis of clinically significant portal hypertension (CSPH) in patients with compensated advanced chronic liver disease (cACLD). The performance of Baveno VII criteria for assessing CSPH by two-dimensional shear wave elastography (2D-SWE) had not been well validated. We aimed to validate the performance of Baveno VII criteria for rule-in and rule-out CSPH by 2D-SWE.

METHOD

This is an international multicenter study including cACLD patients from China and Croatia with paired liver stiffness measurement (LSM), spleen stiffness measurement (SSM) by 2D-SWE, and hepatic venous pressure gradient (HVPG) were included. CSPH was defined as HVPG ≥ 10 mmHg.

RESULT

A total of 146 patients with cACLD were enrolled, and finally 118 patients were included in the analysis. Among them, CSPH was documented in 79 (66.9%) patients. Applying the Baveno VII criteria for rule-out CSPH by 2D-SWE, [LSM ≤ 15 kPa and platelet count ≥ 150 × 109/L] OR SSM < 21 kPa, could exclude CSPH with sensitivity > 90% (93.5 or 98.7%) but negative predictive value < 90% (74.1 or 85.7%). Using the Baveno VII criteria for rule-in CSPH by 2D-SWE, LSM ≥ 25 kPa OR SSM ≥ 50 kPa, could diagnose CSPH with 100% specificity and 100% positive predictive values.

CONCLUSION

Baveno VII criteria by 2D-SWE showed a good diagnostic performance for ruling in but not for ruling out CSPH, which might become an emerging non-invasive elastography tool to select the patients who needed non-selective beta blocker therapy.

Determining the ideal measurement site and respiratory condition for liver transient elastography: toward clinical practice standardization

OBJECTIVES

Liver transient elastography (TE) has been endorsed by the WHO as the first-line diagnostic tool for liver diseases. Although unreliable and invalid results caused by intercostal space (ICS)-associated factors (including excessive subcutaneous fat and a narrow ICS relative to the transducer size) and operator inexperience are not uncommon, no standard guidelines for ideal probe placement are currently available. Herein, we conducted a prospective observational study to identify an ideal measurement site and respiratory condition for TE by characterizing anatomical and biomechanical properties of the ICSs using ultrasound B-mode and elasticity imaging.

METHODS

Intercostal ultrasound was performed pointwise at four specific sites in 59 patients to simultaneously measure the width, stiffness, and skin‒liver capsule distance (SCD) of the ICSs over the liver, under end-inspiratory and end-expiratory conditions. Intersections between the 8th ICS and anterior axillary line, the 7th ICS and anterior axillary line, the 8th ICS and mid-axillary line, and the 7th ICS and mid-axillary line were defined as Sites 1 to 4, respectively.

RESULTS

Results indicated that Sites 2 and 3 presented greater intercostal width; Sites 3 and 4 displayed lower intercostal stiffness; Sites 2 and 3 exhibited a shorter SCD. The ICSs were significantly wider and stiffer at end-inspiration. Additionally, the liver was more easily visualized at Sites 1 and 3.

CONCLUSION

We recommend Site 3 for TE probe placement owing to its greater width, lower stiffness, and smaller abdominal wall thickness. Performing TE at end-inspiration is preferred to minimize transducer-rib interferences. This study paves the way toward a standardized TE examination procedure.

CRITICAL RELEVANCE STATEMENT

A standardized measurement protocol for WHO-recommended liver TE was first established to improve the success and efficiency of the examination procedure.

KEY POINTS

WHO-recommended TE is unreliable or fails due to intercostal space-related factors. The 8th intercostal space on the mid-axillary line and end-inspiration are recommended. This standardized protocol aids in handling challenging cases and simplifies operational procedures.

Validating the Baveno Elastography Criteria of Advanced Liver Fibrosis in Two-Dimensional Shear Wave Elastography: A Prospective Pathology-Based Study

INTRODUCTION

The Baveno criteria for assessing advanced liver fibrosis were mainly determined by transient elastography (TE), and its pathology-based validation studies in two-dimensional shear wave elastography (2D-SWE) remain limited. We aimed to validate the Baveno criteria through use of 2D-SWE.

METHOD

Consecutive patients who underwent liver biopsies for various benign liver diseases were prospectively recruited. Liver stiffness measurement (LSM) was simultaneously evaluated by TE and 2D-SWE. The optimal cutoff value to predict advanced liver fibrosis was determined by the Youden Index, and the diagnostic performance was estimated using area under the receiver operating characteristic (AUROC) analysis.

RESULTS

A total of 101 patients were enrolled having a median age of 55.0 (IQR: 46.0-63.5) years, with 53 (52.48%) of them being male. Using <9 and >14 kPa as the optimal dual cutoffs, the AUROC values in TE and 2D-SWE were 0.92 (95% CI: 0.83-0.97) and 0.93 (95% CI: 0.84-0.98), respectively (p = 0.61). The sensitivity and specificity of LSM by TE/2D-SWE achieved rates of 94.44%/94.44% and 86.00%/88.00%, respectively. However, using the Baveno criteria, the AUROC values in TE and 2D-SWE could remain achieving 0.91 (95% CI: 0.82-0.97) and 0.93 (95% CI: 0.84-0.98), respectively (p = 0.36). The sensitivity and specificity in TE/2D-SWE were 88.24%/88.24% and 86.79%/90.57%, respectively.

CONCLUSION

This study establishes the compatibility of the Baveno dual cutoff criteria with 2D-SWE, positioning it as an easily used criteria in clinical practice and research.

Clinical value of [18F]AlF-NOTA-FAPI-04 PET/CT for assessing early-stage liver fibrosis in adult liver transplantation recipients compared with chronic HBV patients

AIMS

To investigate the clinical value and performance of [18F]AlF-NOTA-FAPI-04 PET/CT in assessing early-stage liver fibrosis in liver transplantation (LT) recipients.

METHODS

A prospective study including 17 LT recipients and 12 chronic Hepatitis B (CHB) patients was conducted. All patients received liver biopsy, transient elastography (TE), and [18F]AlF-NOTA-FAPI-04 PET/CT. On [18F]AlF-NOTA-FAPI-04 PET/CT scans, the liver parenchyma's maximum standardized uptake values (SUVmax) were measured. The receiver operating characteristic (ROC) curve analysis was applied to determine the diagnostic efficacy of [18F]AlF-NOTA-FAPI-04 PET/CT in early-stage liver fibrosis (S1-S2) compared with the diagnostic performance of TE.

RESULTS

Among those 29 patients enrolled in this study, 15(51.7%) had fibrosis S0, 10(34.5%) had S1, and 4(13.8%) had S2, respectively. The SUVmax of patients with early-stage liver fibrosis was significantly higher than those without liver fibrosis in LT recipients and CHB patients (P = 0.004, P = 0.02). In LT recipients, a SUVmax cut-off value of 2.0 detected early-stage liver fibrosis with an AUROC of 0.92 (P = 0.006), and a liver stiffness measurements (LSM) score cut-off value of 8.2 kPa diagnosed early-stage liver fibrosis with an AUROC of 0.80 (P = 0.012). In CHB patients, a SUVmax cut-off value of 2.7 detected early-stage liver fibrosis with an AUROC of 0.94 (P < 0.001) and an LSM scores cut-off value of 8.4 kPa diagnosed early-stage liver fibrosis with an AUROC of 0.91 (P < 0.001).

CONCLUSION

[18F]AlF-NOTA-FAPI-04 PET/CT could be applied to evaluate early-stage liver fibrosis in LT recipients and CHB patients properly, with the potential additional advantages in monitoring and predicting complications after LT.

Performance evaluation of commercial and non-commercial shear wave elastography implementations for vascular applications

BACKGROUND

Shear wave elastography (SWE) is mainly used for stiffness estimation of large, homogeneous tissues, such as the liver and breasts. However, little is known about its accuracy and applicability in thin (∼0.5-2 mm) vessel walls. To identify possible performance differences among vendors, we quantified differences in measured wave velocities obtained by commercial SWE implementations of various vendors over different imaging depths in a vessel-mimicking phantom. For reference, we measured SWE values in the cylindrical inclusions and homogeneous background of a commercial SWE phantom. Additionally, we compared the accuracy between a research implementation and the commercially available clinical SWE on an Aixplorer ultrasound system in phantoms and in vivo in patients.

METHODS

SWE measurements were performed over varying depths (0-35 mm) using three ultrasound machines with four ultrasound probes in the homogeneous 20 kPa background and cylindrical targets of 10, 40, and 60 kPa of a multi-purpose phantom (CIRS-040GSE) and in the anterior and posterior wall of a homogeneous polyvinyl alcohol vessel-mimicking phantom. These phantom data, along with in vivo SWE data of carotid arteries in 23 patients with a (prior) head and neck neoplasm, were also acquired in the research and clinical mode of the Aixplorer ultrasound machine. Machine-specific estimated phantom stiffness values (CIRS phantom) or wave velocities (vessel phantom) over all depths were visualized, and the relative error to the reference values and inter-frame variability (interquartile range/median) were calculated. Correlations between SWE values and target/vessel wall depth were explored in phantoms and in vivo using Spearman's correlations. Differences in wave velocities between the anterior and posterior arterial wall were assessed with Wilcoxon signed-rank tests. Intra-class correlation coefficients were calculated for a sample of ten patients as a measure of intra- and interobserver reproducibility of SWE analyses in research and clinical mode.

RESULTS

There was a high variability in obtained SWE values among ultrasound machines, probes, and, in some cases, with depth. Compared to the homogeneous CIRS-background, this variation was more pronounced for the inclusions and the vessel-mimicking phantom. Furthermore, higher stiffnesses were generally underestimated. In the vessel-mimicking phantom, anterior wave velocities were (incorrectly) higher than posterior wave velocities (3.4-5.6 m/s versus 2.9-5.9 m/s, p ≤ 0.005 for 3/4 probes) and remarkably correlated with measurement depth for most machines (Spearman's ρ = -0.873-0.969, p < 0.001 for 3/4 probes). In the Aixplorer's research mode, this difference was smaller (3.3-3.9 m/s versus 3.2-3.6 m/s, p = 0.005) and values did not correlate with measurement depth (Spearman's ρ = 0.039-0.659, p ≥ 0.002). In vivo, wave velocities were higher in the posterior than the anterior vessel wall in research (left p = 0.001, right p < 0.001) but not in clinical mode (left: p = 0.114, right: p = 0.483). Yet, wave velocities correlated with vessel wall depth in clinical (Spearman's ρ = 0.574-0.698, p < 0.001) but not in research mode (Spearman's ρ = -0.080-0.466, p ≥ 0.003).

CONCLUSIONS

We observed more variation in SWE values among ultrasound machines and probes in tissue with high stiffness and thin-walled geometry than in low stiffness, homogeneous tissue. Together with a depth-correlation in some machines, where carotid arteries have a fixed location, this calls for caution in interpreting SWE results in clinical practice for vascular applications.

Ultrasound Viscoelastography by Acoustic Radiation Force: A State-of-the-Art Review

Ultrasound elastography (USE) is a promising tool for tissue characterization as several diseases result in alterations of tissue structure and composition, which manifest as changes in tissue mechanical properties. By imaging the tissue response to an applied mechanical excitation, USE mimics the manual palpation performed by clinicians to sense the tissue elasticity for diagnostic purposes. Next to elasticity, viscosity has recently been investigated as an additional, relevant, diagnostic biomarker. Moreover, since biological tissues are inherently viscoelastic, accounting for viscosity in the tissue characterization process enhances the accuracy of the elasticity estimation. Recently, methods exploiting different acquisition and processing techniques have been proposed to perform ultrasound viscoelastography. After introducing the physics describing viscoelasticity, a comprehensive overview of the currently available USE acquisition techniques is provided, followed by a structured review of the existing viscoelasticity estimators classified according to the employed processing technique. These estimators are further reviewed from a clinical usage perspective, and current outstanding challenges are discussed.

Ultrasound Shear Wave Propagation Modeling in General Tissue-Like Viscoelastic Materials

OBJECTIVE

This study aims to present an approach for the simulation of ultrasound elastic waves propagation in a diverse range of heterogeneous tissue-like viscoelastic materials, including, but not limited to, Kelvin-Voigt, Zener, Maxwell, Burger's, and Maxwell-Wiechert models, while also allowing for modeling highly viscous fluids.

METHODS

Ultrasound shear wave elastography (SWE) serves as a cost-effective modality for noninvasive, quantitative assessment of soft tissue viscoelastic mechanical properties. To explore tissue viscoelasticity, measuring the shear wave phase velocity in the frequency domain is a common method. In this paper, we employ modeling and numerical simulations to enhance the development of SWE methods. The study employs the staggered grid finite difference (SGFD) method along with recursive calculations of convolution integrals pertinent to linear viscoelastic models.

RESULTS

The presented numerical method demonstrates its capability to simulate the propagation of ultrasound elastic waves, both longitudinal and shear, across a broad spectrum of tissue-like viscoelastic heterogeneous materials. The approach successfully accommodates various viscoelastic models without requiring additional modifications in the numerical model, thus enabling a comprehensive exploration of different viscoelastic behaviors commonly observed in diverse tissue types.

CONCLUSION

The developed combination of the SGFD method and recursive calculation of convolution integrals presents a novel and versatile approach in modeling linear viscoelastic tissue-like materials for SWE applications. This method eliminates the need for model-specific adaptations in numerical simulations, thereby offering flexibility for exploring and understanding diverse viscoelastic behaviors inherent in different heterogeneous tissue types, contributing significantly to the advancement of ultrasound SWE for diagnostic purposes.

US-based Sequential Algorithm Integrating an AI Model for Advanced Liver Fibrosis Screening

Background Noninvasive tests can be used to screen patients with chronic liver disease for advanced liver fibrosis; however, the use of single tests may not be adequate. Purpose To construct sequential clinical algorithms that include a US deep learning (DL) model and compare their ability to predict advanced liver fibrosis with that of other noninvasive tests. Materials and Methods This retrospective study included adult patients with a history of chronic liver disease or unexplained abnormal liver function test results who underwent B-mode US of the liver between January 2014 and September 2022 at three health care facilities. A US-based DL network (FIB-Net) was trained on US images to predict whether the shear-wave elastography (SWE) value was 8.7 kPa or higher, indicative of advanced fibrosis. In the internal and external test sets, a two-step algorithm (Two-step#1) using the Fibrosis-4 Index (FIB-4) followed by FIB-Net and a three-step algorithm (Three-step#1) using FIB-4 followed by FIB-Net and SWE were used to simulate screening scenarios where liver stiffness measurements were not or were available, respectively. Measures of diagnostic accuracy were calculated using liver biopsy as the reference standard and compared between FIB-4, SWE, FIB-Net, and European Association for the Study of the Liver guidelines (ie, FIB-4 followed by SWE), along with sequential algorithms. Results The training, validation, and test data sets included 3067 (median age, 42 years [IQR, 33-53 years]; 2083 male), 1599 (median age, 41 years [IQR, 33-51 years]; 1124 male), and 1228 (median age, 44 years [IQR, 33-55 years]; 741 male) patients, respectively. FIB-Net obtained a noninferior specificity with a margin of 5% (P < .001) compared with SWE (80% vs 82%). The Two-step#1 algorithm showed higher specificity and positive predictive value (PPV) than FIB-4 (specificity, 79% vs 57%; PPV, 44% vs 32%) while reducing unnecessary referrals by 42%. The Three-step#1 algorithm had higher specificity and PPV compared with European Association for the Study of the Liver guidelines (specificity, 94% vs 88%; PPV, 73% vs 64%) while reducing unnecessary referrals by 35%. Conclusion A sequential algorithm combining FIB-4 and a US DL model showed higher diagnostic accuracy and improved referral management for all-cause advanced liver fibrosis compared with FIB-4 or the DL model alone. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Ghosh in this issue.

SWENet: A Physics-Informed Deep Neural Network (PINN) for Shear Wave Elastography

Shear wave elastography (SWE) enables the measurement of elastic properties of soft materials in a non-invasive manner and finds broad applications in various disciplines. The state-of-the-art SWE methods rely on the measurement of local shear wave speeds to infer material parameters and suffer from wave diffraction when applied to soft materials with strong heterogeneity. In the present study, we overcome this challenge by proposing a physics-informed neural network (PINN)-based SWE (SWENet) method. The spatial variation of elastic properties of inhomogeneous materials has been introduced in the governing equations, which are encoded in SWENet as loss functions. Snapshots of wave motions have been used to train neural networks, and during this course, the elastic properties within a region of interest illuminated by shear waves are inferred simultaneously. We performed finite element simulations, tissue-mimicking phantom experiments, and ex vivo experiments to validate the method. Our results show that the shear moduli of soft composites consisting of matrix and inclusions of several millimeters in cross-section dimensions with either regular or irregular geometries can be identified with excellent accuracy. The advantages of the SWENet over conventional SWE methods consist of using more features of the wave motions and enabling seamless integration of multi-source data in the inverse analysis. Given the advantages of SWENet, it may find broad applications where full wave fields get involved to infer heterogeneous mechanical properties, such as identifying small solid tumors with ultrasound SWE, and differentiating gray and white matters of the brain with magnetic resonance elastography.

Comparison of Transient Elastography and Point Shear Wave Elastography for Analysis of Liver Stiffness: A Prospective Study

Liver stiffness measurement (LSM) by Fibroscan is the most used non-invasive method to assess liver fibrosis. Recently, point-shear wave elastography (pSWE) has been introduced as a simple alternative non-invasive test. Therefore, we aimed to compare the results of these two techniques. One hundred and eighty-four consecutive patients attending our outpatient ultrasound clinic were recruited. LSM was performed by both Fibroscan and pSWE. Statistical analysis was conducted by Spearman's test for correlation and linear regression. Bland-Altman graphs and ROC curves were drawn with area under the curve (AUC). Overall, the correlation of LS between Fibroscan and pSWE was substantial (r = 0.68, p < 0.001). Linear regression showed a coefficient b= 0.94 ± 0.02. The Bland-Altman plot found a bias of -0.10, with only 11 values exceeding the 95% confidence interval. When only considering patients with a LSM of > 10 kPa (n = 31), we found an excellent r = 0.79 (0.60-0.90, p < 0.001). A cutoff of 12.15 kPa for pSWE had sensitivity = 74.2% and specificity = 99.3% to detect relevant fibrosis, with an AUC = 0.98. The highest correlation was observed for hepatitis C (r = 0.91) and alcoholic liver disease (ALD)(r = 0.99). In conclusion, pSWE shows LSM estimation in agreement with Fibroscan in most cases, and the best concordance was observed for hepatitis C and ALD, and for higher ranges of LS.

Advancements in metabolic-associated steatotic liver disease research: Diagnostics, small molecule developments, and future directions

Metabolic (dysfunction)-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease, is a growing global health concern with no approved pharmacological treatments. At the same time, there are no standard methods to definitively screen for the presence of MASLD because of its progressive nature and symptomatic commonality with other disorders. Recent advances in molecular understanding of MASLD pathophysiology have intensified research on development of new drug molecules, repurposing of existing drugs approved for other indications, and an educated use of dietary supplements for its treatment and prophylaxis. This review focused on depicting the latest advancements in MASLD research related to small molecule development for prophylaxis or treatment and diagnosis, with emphasis on mechanistic basis at the molecular level.

A Case of Idiopathic Portal Hypertension Diagnosed by Noninvasive Fibrosis Evaluation Using Elastography

Idiopathic portal hypertension (IPH) is often misdiagnosed as liver cirrhosis. Because it is difficult to distinguish between the two using diagnostic imaging, invasive tests, such as pathology and hepatic vein pressure gradient measurement, are necessary to make a diagnosis. Several studies have shown that the measurement of liver and spleen stiffnesses using elastography is useful in the diagnosis of IPH; however, there are few concrete reports on this subject. Herein, we report the case of a 58-year-old woman with IPH in which elastography was helpful for the diagnosis.

Depth effect on point shear wave velocity elastography: Evidence in a chronic hepatitis C patient cohort

Background and Aims

This study investigated the depth-related bias and the influence of scan plane angle on performance of point-shear-wave elastometry in a chronic hepatitis C patient cohort.

Materials and Methods

We included 104 patients affected by chronic liver disease related to the hepatitis C virus. Liver surface nodularity was the reference to diagnose cirrhosis. The ultrasound platform was the Siemens S2000, equipped with point-shear-wave elastometry software. Measurements were obtained in left lateral decubitus from the liver surface to the maximum depth of 8 cm in two orthogonal scan planes according to a standard sampling plane. Scatterplot and box plots explored the depth-related bias graphically. The area under the receiver operating characteristic was used to determine the point-shear-wave elastometry diagnostic performance at progressive depths according to liver surface nodularity.

Results

Of the 104 patients, 68 were cirrhotics. Depth-related bias equally modified point-shear-wave elastometry in the two orthogonal scan planes. A better point-shear-wave elastometry diagnostic performance was observed between depths of 4 and 5 cm. The frontal scan plane assured better discrimination between cirrhotic patients and non-cirrhotic patients.

Conclusion

Depth is crucial for point-shear-wave elastometry performance. Excellent diagnostic performance at a depth between 4 and 5 cm can also be obtained with a smaller number of measurements than previously recommended.

Hepatic steatosis using ultrasound-derived fat fraction: First technical and clinical evaluation

OBJECTIVES

To explore the technical and clinical evaluation of ultrasound-derived fat fraction (UDFF) measurement in adult patients in whom fatty liver was suspected.

MATERIALS AND METHODS

In this prospective study, 41 participants were initially enrolled in our hospital between October 2022 and December 2022 and received UDFF assessment using Siemens ACUSON Sequoia system equipped with DAX transducer. UDFF measurement was performed three times to obtain UDFF values from each imaging location (V hepatic segment and VIII hepatic segment) per participant, and the depth (skin-to-capsule distance) was automatically measured. The echogenicity of liver tissue in B mode ultrasound (BMUS) was compared to the normal kidney tissue, and fatty liver was graded as mild (Grade 1), moderate (Grade 2), and severe (Grade 3). The median of the acquired overall median UDFF values was used for statistical analysis. All ultrasound examinations were performed by one of two radiologists (with 20 and 10 years of liver ultrasound imaging experience).

RESULTS

Finally, UDFF measurement was successfully performed on 38 participants to obtain valid values, including 21 men with a median age of 40.0 years (interquartile range [IQR]: 23.0 - 58.5) and 17 women with a median age of 60.0 years (IQR: 29.5 - 67.0). Fatty liver was diagnosed by BMUS features in 47.4% (18/38) participants. Among all participants, the median UDFF value was 7.0% (IQR: 4.0 - 15.6). A significant difference in UDFF values was found between participants with fatty liver and without fatty liver (U = 7.0, P < 0.001), and UDFF values elevated as the grade of the fatty liver increased (P < 0.001). The median UDFF values from the three UDFF measurements obtained during each ultrasound examination showed excellent agreement (ICC = 0.882 [95% confidence interval: 0.833 - 0.919]). The Spearman correlation of UDFF values in different depths was moderate, with a rs value of 0.546 (P < 0.001). No significant differences in UDFF values were found between V hepatic segment and VIII hepatic segment (U = 684.5, P = 0.697).

CONCLUSIONS

UDFF provides a novel non-invasive imaging tool for hepatic steatosis assessment with excellent feasibility.

Preoperative ultrasound radiomics for predicting clinically relevant postoperative pancreatic fistula after pancreatectomy

OBJECTIVES

To evaluate the efficacy of the radiomics model based on preoperative B-mode ultrasound (BMUS) and shear wave elastography (SWE) for predicting the occurrence of clinically relevant-postoperative pancreatic fistula (CR-POPF).

METHODS

Patients who were scheduled to undergo pancreatectomy were prospectively enrolled and received ultrasound assessment within one week before surgery. The risk factors of POPF (grades B and grades C) were analyzed. Preoperative BMUS images, SWE values of pancreatic lesions and surrounding parenchyma were used to build preoperative prediction radiomics models. Radiomic signatures were extracted and constructed using a minimal Redundancy Maximal Relevance (mRMR) algorithm and an L1 penalized logistic regression. A combined model was built using multivariate regression which incorporated radiomics signatures and clinical data.

RESULTS

From January 2020 to November 2021, a total of 147 patients (85 distal pancreatectomies and 62 pancreaticoduodenectomies) were enrolled. During the three-week follow-up after pancreatectomy, the incidence rates of grade B/C POPF were 28.6% (42/147). Radiomic signatures constructed from BMUS of pancreas parenchymal regions (panRS) achieved an area under the receiver operating characteristic curve (AUC) of 0.75, accuracy of 68.7%, sensitivity of 85.7 %, and specificity of 61.9 % in preoperative noninvasive prediction of CR-POPF. The AUC of the radiomics model increased to 0.81 when panRS was used for the prediction of CR-POPF after pancreaticoduodenectomy.

CONCLUSIONS

Radiomics model based on ultrasound images was potentially useful for predicting CR-POPF. Patients with high-risk factors should be closely monitored when postoperation.

Imaging of Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) continues to be a global health concern, responsible for a significant number of deaths worldwide. Although most individuals who consume alcohol do not develop ALD, heavy drinkers and binge drinkers are at increased risk. Unfortunately, ALD is often undetected until it reaches advanced stages, frequently associated with portal hypertension and hepatocellular carcinoma (HCC). ALD is now the leading indication for liver transplant. The incidence of alcohol-associated hepatitis (AH) surged during the COVID-19 pandemic. Early diagnosis of ALD is therefore important in patient management and determination of prognosis, as abstinence can halt disease progression. The spectrum of ALD includes steatosis, steatohepatitis, and cirrhosis, with steatosis the most common manifestation. Diagnostic techniques including ultrasound, CT, and MRI provide useful information for identifying ALD and excluding other causes of liver dysfunction. Heterogeneous steatosis and transient perfusion changes on CT and MRI in the clinical setting of alcohol-use disorder are diagnostic of severe AH. Elastography techniques are useful for assessing fibrosis and monitoring treatment response. These various imaging modalities are also useful in HCC surveillance and diagnosis. This review discusses the imaging modalities currently used in the evaluation of ALD, highlighting their strengths, limitations, and clinical applications.

Evaluation of levator ani muscle elasticity after vaginal delivery and cesarean section using shear wave elastography

PURPOSE

The risk of pelvic floor muscle injury is commonly considered to be higher in vaginal than in cesarean delivery. This study aimed to compare levator ani muscle (LAM) elasticity after vaginal and cesarean delivery using shear wave elastography (SWE).

METHODS

Postpartum women who underwent a single SWE evaluation 1 month after their first delivery were divided into vaginal and cesarean delivery groups. The elastic moduli of both sides of the LAM were measured in a horizontal section and compared between the groups. In addition, a subgroup analysis was performed to compare LAM elasticity according to the delivery method within the vaginal delivery group-normal vaginal delivery, episiotomy, and operative vaginal delivery.

RESULTS

Sixty-two women were included (vaginal delivery, n = 47; elective cesarean section, n = 15). Multiple regression analysis revealed that the LAM elastic modulus was significantly lower in the vaginal delivery group than in the cesarean delivery group (right LAM: 44.2 vs. 72.7 kPa, p = 0.0036; left LAM 40.4 vs. 82.7 kPa, p < 0.0001). In the subgroup analysis, the right LAM elastic modulus was significantly lower in the operative vaginal delivery subgroup than in the normal vaginal delivery subgroup (p = 0.0131). However, there was no significant difference in the left LAM elastic modulus between the three subgroups.

CONCLUSION

LAM elasticity was significantly lower after vaginal delivery than after cesarean delivery. Furthermore, the elasticity of the right LAM was lower after operative vaginal delivery than after normal vaginal delivery. SWE has the potential to provide an objective quantitative assessment of postpartum pelvic floor muscle recovery.

Determination and prospective validation of cut-off values for the diagnosis of liver cirrhosis for point shear-wave elastography/acoustic radiation force impulse imaging using the ACUSON Sequoia ultrasound system

OBJECTIVES

Point shear-wave elastography (pSWE) alias acoustic radiation force impulse (ARFI) imaging is a well-established ultrasound-based technique for the non-invasive assessment of liver tissue stiffness. As cut-off values for liver cirrhosis cannot be transferred from one ultrasound system to another, this study aimed at determining cut-off values for the newly developed Siemens ACUSON Sequoia ultrasound system.

METHODS

In a pilot study phase, two independent examiners conducted 10 pSWE measurements in an elasticity phantom and 32 healthy individuals for the determination of inter-examiner agreement. Afterwards, 22 cirrhotic patients and 57 patients with chronic liver disease undergoing liver biopsy underwent pSWE. Patient characteristics and stiffness values were compared for individuals with and without liver cirrhosis. Diagnostic accuracies of cut-off values for the diagnosis of liver cirrhosis were calculated using areas under the receiver operating characteristics analysis and Youden's index. In a subsequent validation study phase, these cut-off values were validated prospectively in 107 cirrhotic and 68 non-cirrhotic patients.

RESULTS

Inter-examiner agreement was excellent for measurements in the elasticity phantom (intra-class correlation coefficient [ICC] = 0.998; P  < 0.001), and good for measurements in patients (ICC = 0.844; P  < 0.001). The best cut-off value for the diagnosis of liver cirrhosis was 1.405 m/s with an AUC of 0.872, a sensitivity of 88.2% and a specificity of 88.2% ( P  < 0.001).

CONCLUSION

ARFI elastography using the Siemens ACUSON Sequoia showed a good inter-examiner agreement. The optimal cut-off value was lower than the cut-off values described for former generations of ultrasound devices. These preliminary results should be confirmed in larger patient collectives with histology as the reference standard.

Associations of Liver Stiffness Measured by Ultrasound Shear-Wave Elastography With Portal Hypertension and Circulatory Failure in Individuals With Fontan Circulation

BACKGROUND. The Fontan operation palliates single-ventricle congenital heart disease but causes hepatic congestion with associated progressive hepatic fibrosis. OBJECTIVE. The purpose of this study was to evaluate associations between liver stiffness measured using ultrasound (US) shear-wave elastography (SWE) in patients with Fontan palliation and the occurrence of portal hypertension and Fontan circulatory failure during follow-up. METHODS. This retrospective study included 119 individuals 10 years old or older (median age, 19.1 years; 61 female patients, 58 male patients) with Fontan circulation who underwent liver US with 2D SWE from January 1, 2015, to January 1, 2022, and had 1 year or more of clinical follow-up (unless experiencing earlier outcome-related events). Median liver stiffness from the initial US examination was documented. Varices, ascites, splenomegaly, and thrombocytopenia (VAST) scores (range, 0-4) were determined as a marker of portal hypertension on initial US examination and 1 year or more of follow-up imaging (US, CT, or MRI). Composite clinical outcome for Fontan circulatory failure (death, mechanical circulatory support, cardiac transplant, or unexpected Fontan circulation-related hospitalization) was assessed. Analysis included the Wilcoxon rank sum test, logistic regression analysis with stepwise variable selection, and ROC analysis. RESULTS. Median initial liver stiffness was 2.22 m/s. Median initial VAST score was 0 (IQR, 0-1); median follow-up VAST score was 1 (IQR, 0-2) (p = .004). Fontan circulatory failure occurred in 37 of 119 (31%) patients (median follow-up, 3.4 years). Initial liver stiffness was higher in patients with a follow-up VAST score of 1 or greater (2.37 m/s) than in those with a follow-up VAST score of 0 (2.08 m/s) (p = .005), and initial liver stiffness was higher in patients with (2.43 m/s) than without (2.10 m/s) Fontan circulatory failure during follow-up (p < .001). Initial liver stiffness was the only significant independent predictor of Fontan circulatory failure (OR = 3.76; p < .001); age, sex, Fontan operation type, dominant ventricular morphology, and initial VAST score were not independent predictors. Initial liver stiffness had an AUC of 0.70 (sensitivity, 79%; specificity, 57%; threshold, > 2.11 m/s) for predicting a follow-up VAST score of 1 or greater and an AUC of 0.74 (sensitivity, 84%; specificity, 52%; threshold, > 2.12 m/s) for predicting Fontan circulatory failure. CONCLUSION. In patients with Fontan circulation, increased initial liver stiffness was associated with portal hypertension and circulatory failure during follow-up, although it had moderate performance in predicting these outcomes. CLINICAL IMPACT. US SWE may play a role in post-Fontan surveillance, supporting tailored medical and surgical care.

Identifying inflammatory bowel disease patients at risk of metabolic dysfunction-associated fatty liver disease: usefulness of non-invasive steatosis predictive scores

BACKGROUND

Inflammatory bowel disease (IBD) patients have a higher risk of metabolic dysfunction-associated fatty liver disease (MAFLD) compared with the general population. However, it is not known whether available non-invasive hepatic steatosis scores are useful in predicting MAFLD in IBD patients. We aimed to analyze the performances of MAFLD screening score (MAFLD-S), Fatty Liver Index (FLI), Hepatic Steatosis Index (HSI) and Clinical Prediction Tool for NAFLD in Crohn's Disease (CPN-CD), in identifying MAFLD in IBD patients.

METHODS

A cross-sectional study was carried out including consecutive adult IBD outpatients submitted to transient elastography (TE). MAFLD criteria were assessed, and hepatic steatosis (HS) was defined by a controlled attenuation parameter (CAP) >248 dB/m using TE. MAFLD-S, FLI, HSI, and CPN-CD were calculated and their accuracy for the prediction of MAFLD was evaluated through their areas under the receiver-operating characteristic (AUROC) curves.

RESULTS

Of 168 patients, body mass index ≥25, type 2 diabetes mellitus, dyslipidemia and arterial hypertension were present in 76 (45.2%), 10 (6.0%), 53 (31.5%), 20 (11.9%), respectively. HS was identified in 77 (45.8%) patients, of which 65 (84.4%) fulfilled MAFLD criteria. MAFLD-S (AUROC, 0.929 [95% CI, 0.888-0.971]) had outstanding and FLI (AUROC, 0.882 [95% CI, 0.830-0.934]), HSI (AUROC, 0.803 [95% CI, 0.736-0.871]), and CPN-CD (AUROC, 0.822 [95% CI, 0.753-0.890) had excellent discrimination in predicting MAFLD.

CONCLUSIONS

MAFLD-S, FLI, HSI and CPN-CD scores can accurately identify MAFLD in IBD patients, allowing the selection of those in whom hepatic steatosis and metabolic risk factors assessment may be particularly beneficial.