Determination of normal hepatic elasticity by using real-time shear-wave elastography

Real-time shear wave elastography in measuring normal ileocolon intestinal wall stiffness using colonoscopy as reference: A single-center research

Purpose

To investigate the feasibility of real-time shear wave elastography (SWE) in evaluating intestinal wall stiffness, and to establish the threshold SWE value of normal intestinal wall and explore the influencing factors of intestinal SWE.

Method

659 subjects who underwent intestinal SWE and colonoscopy were retrospectively enrolled. The wall elasticity of colonoscopy-confirmed normal/abnormal intestinal segment was measured by transabdominal SWE. Measurement reliability was evaluated by the intraclass correlation coefficient (ICC). The threshold value of SWE in differentiating normal and abnormal intestine was determined using ROC curve analysis with the largest Youden index, and the diagnostic performance of this threshold was evaluated. We explored the effects of gender, age, depth and type of the targeted intestinal segment on the intestinal wall elasticity by t test and logistic linear regression analysis.

Results

The technical success rate of SWE examination is 95.3 % (628/659). The mean SWE value of normal intestinal walls is (5.45 ± 1.34) kPa, which was significantly lower than that of abnormal ones (15.38 kPa±7.22, P < 0.001). Using 8.1 kPa as the threshold， the sensitivity and specificity were 93.5 % and 96.0 % with an AUC of 94.8 %. The overall ICC for SWE measurements was 0.933. Gender (ß=0.278, P = 0.013), depth (ß=0.220, P = 0.043) and type of the targeted segment (ß=0.522, P < 0.001) was associated with the SWE value of intestinal wall, but age was not (ß=0.050, P = 0.484).

Conclusions

SWE is feasible in evaluating the stiffness of intestinal wall with high reliability. The SWE threshold value differentiating normal intestinal wall and abnormal intestinal wall is 8.1 kPa.

Multi-omics analyses of the gut microbiota and metabolites in children with metabolic dysfunction-associated steatotic liver disease

The development and severity of metabolic dysfunction-associated steatotic liver disease (MASLD) in children are closely related to alterations of gut microbiota. This study aims to investigate changes in the gut microbiota signature and microbial metabolites in children with MASLD. We collected fecal samples from children and adolescents aged 6-16 years, and the presence of MASLD was diagnosed by ultrasound. We performed 16S ribosomal DNA sequencing and targeted metabolomics in 36 and 25 subjects, consisting of healthy controls, children with obesity, and children with MASLD. The α-diversity was significantly lower in children with obesity and MASLD compared with healthy controls. Linear discriminant analysis of effect size analysis identified Anaerostipes and A. hadrus as the top biomarkers differentiating the obesity group from the MASLD group. In MASLD patients with high alanine aminotransferase values (≥50 U/L for boys and 44 U/L for girls), we observed a decrease in the gut microbiota health index. MASLD patients with high shear wave elastography (E) values (≥6.2 kPa) showed an increased abundance of Ruminococcus torques, which was positively correlated with the levels of deoxycholic acid (DCA) and E values. Importantly, the mediation analysis identified positive associations between R. torques and clinical indicators of MASLD that were mediated by DCA. Overall, our study suggests that gut microbiota and metabolites are significantly altered in children with MASLD, and targeting R. torques may offer potential benefits for disease management.IMPORTANCEThis study investigated alterations in the gut microbiota signature and microbial metabolites in children with metabolic dysfunction-associated steatotic liver disease (MASLD). We found that an increased abundance of Ruminococcus torques was associated with increased levels of deoxycholic acid and the progression of MASLD, suggesting that R. torques may serve as a novel clinical target in pediatric MASLD.

Quantification of Cervical Elasticity During Pregnancy Based on Transvaginal Ultrasound Imaging and Stress Measurement

Strain elastography and shear wave elastography are commonly used to quantify cervical elasticity. However, the absence of stress information in strain elastography causes difficulty in inter-session elasticity comparison, and the robustness of shear wave elastography is compromised by cervical tissue's high inhomogeneity.

OBJECTIVE

To overcome these limitations, we develop a quantitative cervical elastography system by adding a stress sensor to a clinically used transvaginal ultrasound imaging system.

METHODS

We record the cervical deformation in B-mode images and measure the probe-surface stress through the sensor. Then we quantify the strain using a customized algorithm and estimate the cervical Young's modulus through stress-strain linear regression.

RESULTS

In phantom experiments, we demonstrate the system's high accuracy (alignment with the quasi-static compression method, p-value = 0.369 > 0.05), robustness (alignment between 60°- and 90°-contact measurements, p-value = 0.638 > 0.05), repeatability (consistency of single sonographers' measurements, coefficient of variation < 0.06), and reproducibility (alignment between two sonographers' measurements, Pearson correlation coefficient = 0.981). Applying it to pregnant participants, we observe significant cervical softening (p-value < 0.001): Young's modulus decreases 3.95% weekly and its geometric mean value during the first (11 to 13 weeks), second, and third trimesters are 13.07 kPa, 7.59 kPa, and 4.40 kPa, respectively.

CONCLUSION

The proposed system is accurate, robust, and safe, and enables longitudinal and inter-examiner comparisons.

SIGNIFICANCE

The system applies to different ultrasound machines with minor software updates, which allows for studies of cervical softening patterns in pregnancy for larger populations, facilitating insights into conditions such as preterm birth.

Review of imaging findings in hepatic veno-occlusive disease

Hepatic veno-occlusive disease (VOD), also known as sinusoidal obstruction syndrome (SOS), is a potentially life-threatening complication of hematopoietic stem cell transplantation. Patients present with right upper-quadrant abdominal pain, jaundice, weight gain, and conjugated hyperbilirubinemia. Early diagnosis of VOD is essential to promptly initiate defibrotide therapy, which has been demonstrated to enhance survival and achieve complete resolution of disease in some patients. Historically, VOD was diagnosed by the modified Seattle or Baltimore criteria, which are both based on clinical symptoms. Alongside advancements in medical imaging over the last 40 years, the diagnosis of VOD has evolved to include the use of ultrasound, elastography, cross-sectional imaging, and image guided biopsy. Identification and interpretation of findings of VOD across imaging modalities is now a critical aspect of post-HSCT care. This review will outline the imaging findings and recommendations for the use of imaging in the management of VOD including gray-scale, color and spectral Doppler ultrasound, ultrasound elastography, CT, MRI, and liver biopsy.

Mechanical rheological model on the assessment of elasticity and viscosity in tissue inflammation: A systematic review

Understanding the extent of inflammation is crucial for early disease detection, monitoring disease progression, and evaluating treatment responses. Over the past decade, researchers have demonstrated the need to understand the extent of inflammation through qualitative or quantitative characterization of tissue viscoelasticity using different techniques. In this scientific review, an examination of research on the association between elasticity and Viscosity in diseases, particularly as tissue inflammation progresses, is conducted. A review of utilizing mechanical rheological models to characterize quantitative viscoelastic parameters of normal and inflamed tissues is also undertaken. Based on inclusion and exclusion criteria, we identified 14 full-text studies suitable for review out of 290 articles published from January 2000 to January 2024. We used PRISMA guidelines for the systematic review. In the review, three studies demonstrated the criterion used by the researchers in identifying the best rheological model. Eleven studies showed the clinical application of the rheological model in quantifying the viscoelastic properties of normal and pathological tissue. The review quantified viscoelastic parameters for normal and pathological tissue across various soft tissues. It evaluated the effectiveness of each viscoelastic property in distinguishing between normal and pathological tissue stiffness. Furthermore, the review outlined additional viscoelastic-related parameters for researchers to consider in future stiffness classification studies.

Gelatin-Based Liver Phantoms for Training Purposes: A Cookbook Approach

Background: Patients with liver pathology benefit from image-guided interventions. Training for interventional procedures is recommended to be performed on liver phantoms until a basic proficiency is reached. In the last 40 years, several attempts have been made to develop materials to mimic the imaging characteristics of the human liver in order to create liver phantoms. There is still a lack of accessible, reproducible and cost-effective soft liver phantoms for image-guided procedure training. Methods: Starting from a CT-scan DICOM file, we created a 3D-printed liver mold using InVesalius (Centro de Tecnologia da informação Renato Archer CTI, InVesalius 3 open-source software, Campinas, Brazil) for segmentation, Autodesk Fusion 360 with Netfabb (Autodesk software company, Fusion 360 2.0.19426 with Autodesk Netfabb Premium 2023.0 64-Bit Edition, San Francisco, CA, USA) for 3D modeling and Stratasys Fortus 380 mc 3D printer (Stratasys 3D printing company, Fortus 380 mc 3D printer, Minneapolis, MN, USA). Using the 3D-printed mold, we created 14 gelatin-based liver phantoms with 14 different recipes, using water, cast sugar and dehydrated gelatin, 32% fat bovine milk cream with intravenous lipid solution and technical alcohol in different amounts. We tested all these phantoms as well as ex vivo pig liver and human normal, fatty and cirrhotic liver by measuring the elasticity, shear wave speed, ultrasound attenuation, CT-scan density, MRI signal intensity and fracture force. We assessed the results of the testing performed, as well as the optical appearance on ultrasound, CT and MRI, in order to find the best recipe for gelatin-based phantoms for image-guided procedure training. Results: After the assessment of all phantom recipes, we selected as the best recipe for transparent phantoms one with 14 g of gelatin/100 mL water and for opaque phantom, the recipes with 25% cream. Conclusions: These liver gelatin-based phantom recipes are an inexpensive, reproducible and accessible alternative for training in image-guided and diagnostic procedures and will meet most requirements for valuable training.

Mechanical properties of human hepatic tissues to develop liver-mimicking phantoms for medical applications

Using liver phantoms for mimicking human tissue in clinical training, disease diagnosis, and treatment planning is a common practice. The fabrication material of the liver phantom should exhibit mechanical properties similar to those of the real liver organ in the human body. This tissue-equivalent material is essential for qualitative and quantitative investigation of the liver mechanisms in producing nutrients, excretion of waste metabolites, and tissue deformity at mechanical stimulus. This paper reviews the mechanical properties of human hepatic tissues to develop liver-mimicking phantoms. These properties include viscosity, elasticity, acoustic impedance, sound speed, and attenuation. The advantages and disadvantages of the most common fabrication materials for developing liver tissue-mimicking phantoms are also highlighted. Such phantoms will give a better insight into the real tissue damage during the disease progression and preservation for transplantation. The liver tissue-mimicking phantom will raise the quality assurance of patient diagnostic and treatment precision and offer a definitive clinical trial data collection.

A nomogram incorporating clinical, conventional ultrasound and shear wave elastography findings for distinguishing pleomorphic adenoma from Warthin's tumor of the major salivary glands

OBJECTIVE

Pre-operative differentiation between pleomorphic adenoma (PA) and Warthin's tumor (WT) of the major salivary glands is crucial for treatment decisions. The purpose of this study was to develop and validate a nomogram incorporating clinical, conventional ultrasound (CUS) and shear wave elastography (SWE) features to differentiate PA from WT.

METHODS

A total of 113 patients with histological diagnosis of PA or WT of the major salivary glands treated at Fujian Medical University Union Hospital were enrolled in training cohort (n = 75; PA = 41, WT = 34) and validation cohort (n = 38; PA = 22, WT = 16). The least absolute shrinkage and selection operator (LASSO) regression algorithm was used for screening the most optimal clinical, CUS, and SWE features. Different models, including the nomogram model, clinic-CUS (Clin+CUS) and SWE model, were built using logistic regression. The performance levels of the models were evaluated and validated on the training and validation cohorts, and then compared among the three models.

RESULTS

The nomogram incorporating the clinical, CUS and SWE features showed favorable predictive value for differentiating PA from WT, with the area under the curves (AUCs) of 0.947 and 0.903 for the training cohort and validation cohort, respectively. Decision curve analysis showed that the nomogram model outperformed the Clin+CUS model and SWE model in terms of clinical usefulness.

CONCLUSIONS

The nomogram had good performance in distinguishing major salivary PA from WT and held potential for optimizing the clinical decision-making process.

Evaluation of Liver and Spleen With Shear Wave Elastography in Adult Patients With Familial Mediterranean Fever

ABSTRACT

Familial Mediterranean fever (FMF) is an autoinflammatory disease and an important health problem in countries bordering the eastern Mediterranean, including Turkey. In this study, we aimed to evaluate possible tissue stiffness changes that may develop in the liver and spleen in adult FMF patients with shear wave elastography (SWE), and its usability as an auxiliary imaging method that will be able to provide additional advantage in clinical follow-up. Seventy-five adult FMF patients and 73 adult volunteer were included in the study. Examination was performed through an intercostal space where the liver and spleen were clearly visible. The parenchymal stiffness degrees of the liver and spleen were quantified by shear modulus values in kilopascals. Differences in stiffness values of the liver and spleen between the 2 groups were examined. Liver stiffness value (LSV) was found to be statistically significantly higher in the FMF group. Although the spleen stiffness value (SSV) was found higher in the FMF group, the difference between the groups was not statistically significant. Increased LSVs in patients with FMF can be quantitatively demonstrated by the 2-dimensional SWE method, and SWE may be useful as an auxiliary imaging method in the follow-up of patients with FMF for this purpose. The LSV and SSV obtained in this study may be useful as reference stiffness values for both healthy individuals and those with FMF.

Comparison of Magnetic Resonance-Based Elastography and Ultrasound Shear Wave Elastography in Patients With Suspicion of Nonalcoholic Fatty Liver Disease

ABSTRACT

This study investigated the correlation between magnetic resonance elastography (MRE) and shear wave ultrasound elastography (SWE) in patients with clinically diagnosed or suspected nonalcoholic fatty liver disease (NAFLD). Subjects with or at risk of NAFLD identified by magnetic resonance imaging (MRI) proton density fat fraction (PDFF) were prospectively enrolled. For each patient, 6 valid 2-dimensional SWE measurements were acquired using a Logiq E10 scanner (GE HealthCare, Waukesha, WI). A reliability criterion of an interquartile range to median ratio of ≤15% was used for SWE to indicate quality dataset. Magnetic resonance elastography, and MR-fat quantification data were collected the same day as part of the patient's clinical standard of care. Magnetic resonance imaging PDFF was used as a reference to quantify fat with >6.4% indicating NAFLD. Pearson correlation and t-test were performed for statistical analyses. A total of 140 patients were enrolled, 112 of which met SWE reliability measurement criteria. Magnetic resonance elastography and 2-dimensional SWE showed a positive correlation across all study subjects ( r = 0.27; P = 0.004). When patients were grouped according to steatosis and fibrosis state, a positive correlation was observed between MRE and SWE in patients with fibrosis ( r = 0.30; P = 0.03), without fibrosis ( r = 0.27; P = 0.03), and with NAFLD ( r = 0.28; P = 0.02). No elastography technique correlated with liver fat quantification ( P > 0.52). Magnetic resonance elastography was significantly different between patients with and without fibrosis ( P < 0.0001). However, this difference was not apparent with SWE ( P = 0.09). In patients with suspected or known NAFLD, MRE, and SWE demonstrated a positive correlation. In addition, these noninvasive imaging modalities may be useful adjunct techniques for monitoring NAFLD.

Prediction of Decompensation and Death in Advanced Chronic Liver Disease Using Deep Learning Analysis of Gadoxetic Acid-Enhanced MRI

OBJECTIVE

This study aimed to evaluate the usefulness of quantitative indices obtained from deep learning analysis of gadoxetic acid-enhanced hepatobiliary phase (HBP) MRI and their longitudinal changes in predicting decompensation and death in patients with advanced chronic liver disease (ACLD).

MATERIALS AND METHODS

We included patients who underwent baseline and 1-year follow-up MRI from a prospective cohort that underwent gadoxetic acid-enhanced MRI for hepatocellular carcinoma surveillance between November 2011 and August 2012 at a tertiary medical center. Baseline liver condition was categorized as non-ACLD, compensated ACLD, and decompensated ACLD. The liver-to-spleen signal intensity ratio (LS-SIR) and liver-to-spleen volume ratio (LS-VR) were automatically measured on the HBP images using a deep learning algorithm, and their percentage changes at the 1-year follow-up (ΔLS-SIR and ΔLS-VR) were calculated. The associations of the MRI indices with hepatic decompensation and a composite endpoint of liver-related death or transplantation were evaluated using a competing risk analysis with multivariable Fine and Gray regression models, including baseline parameters alone and both baseline and follow-up parameters.

RESULTS

Our study included 280 patients (153 male; mean age ± standard deviation, 57 ± 7.95 years) with non-ACLD, compensated ACLD, and decompensated ACLD in 32, 186, and 62 patients, respectively. Patients were followed for 11-117 months (median, 104 months). In patients with compensated ACLD, baseline LS-SIR (sub-distribution hazard ratio [sHR], 0.81; p = 0.034) and LS-VR (sHR, 0.71; p = 0.01) were independently associated with hepatic decompensation. The ΔLS-VR (sHR, 0.54; p = 0.002) was predictive of hepatic decompensation after adjusting for baseline variables. ΔLS-VR was an independent predictor of liver-related death or transplantation in patients with compensated ACLD (sHR, 0.46; p = 0.026) and decompensated ACLD (sHR, 0.61; p = 0.023).

CONCLUSION

MRI indices automatically derived from the deep learning analysis of gadoxetic acid-enhanced HBP MRI can be used as prognostic markers in patients with ACLD.

2D-SWE of the Metacarpophalangeal Joint Capsule in Horses

(1) Two-dimensional shear wave elastography (2D-SWE) employs an ultrasound impulse to produce transversely oriented shear waves, which travel through the surrounding tissue according to the stiffness of the tissue itself. The study aimed to assess the reliability of 2D-SWE for evaluating the elastosonographic appearance of the distal attachment of the fetlock joint capsule (DJC) in sound horses and in horses with osteoarthritis (OA) (2). According to a thorough evaluation of metacarpophalangeal joint (MCPJ), adult horses were divided in a sound Group (H) and in OA Group (P). Thereafter, a 2D-SWE of MCPJs was performed. Shear wave velocity (m/sec) and Young’s modulus (kPa) were calculated independently by two operators at each selected ROI. Statistical analysis was performed with R software. (3) Results: 2D-SWE had good–excellent inter-CC and intra-CC in both groups. Differences in m/s and kPa between Groups H and P were found in transverse scans with lower values in Group P. No correlation with age or DJC thickness was found. (4) Conclusions: 2D-SWE was repeatable and reproducible. In Group H, DJC was statistically stiffer than in Group P only in transverse scan. The technique showed poor sensitivity and specificity in differentiating fetlocks affected by OA.

Diagnosis of steatohepatitis and fibrosis in biopsy-proven nonalcoholic fatty liver diseases: including two-dimension real-time shear wave elastography and noninvasive fibrotic biomarker scores

BACKGROUND

The aim of this retrospective study was to evaluate the accuracy of two-dimension real-time shear wave elastography (2D-SWE) for the diagnosis of steatohepatitis and fibrosis in a cohort patients confirmed nonalcoholic fatty liver diseases (NAFLD) by liver biopsy, and compare with four noninvasive fibrotic biomarker scores (NFS, FIB-4, BARD and APRI).

METHODS

116 NAFLD patients and 23 normal control group were enrolled. The diagnostic performance of 2D-SWE and four noninvasive fibrotic biomarker scores was evaluated based on histopathological inflammation grades and fibrosis stages (F) according to Kleiner/Brunt et al.'s criteria classification. 5-fold cross validation and receiver operating characteristics curve (ROC) analyses were used to obtain an assessment of 2D-SWE and four noninvasive fibrotic biomarker scores; then cross validated area under the curves (AUCs) were compared using the test of Delong. Meanwhile, influence of steatosis on liver stiffness measurement (LSM) of 2D-SWE was also studied.

RESULTS

Liver stiffness measured by 2D-SWE proved to be an excellent diagnostic indicator for detecting steatohepatitis (AUROC =0.88), and fibrosis: ≥F2 stage (AUROC =0.86), ≥F3 stage (AUROC =0.89) and =F4 stage (AUROC =0.90) with the cutoff values were 7.3, 10.0, 11.6 and 12.6 kPa, respectively. Compared with fibrotic scores, 2D-SWE had the highest AUROC for predicting ≥F2, ≥F3, =F4 by Delong test (all P<0.05). No statistic differences of LSM were found among different steatosis levels (P=0.97).

CONCLUSIONS

The stiffness measured by 2D-SWE could be used to noninvasively identify steatohepatitis and stage fibrosis in NAFLD patients. Moreover, the diagnosis efficiency of the stiffness measured by 2D-SWE could not be influenced by steatosis.

Pediatric percentiles for transient elastography measurements - effects of age, sex, weight status and pubertal stage

BACKGROUND AND AIMS

Transient Elastography is a non-invasive, cost-efficient, non-ionizing, observer-independent and reliable method to detect liver fibrosis using Liver Stiffness Measurement (LSM) and the degree of fat accumulation in the liver using Controlled Attenuation Parameter (CAP). This study aims to derive reference values for both measures from healthy children and adolescents. Further, we aim to assess the potential influence of age, sex, puberty, and BMI-SDS on CAP and LSM.

METHODS

Within the LIFE Child study, amongst others, anthropometric data and pubertal status were assessed. Transient Elastography (TE) was performed using the FibroScan^® device in a population-based cohort at 982 study visits of 482 healthy children aged between 10 and 18 years. Percentiles for LSM and CAP were estimated, and the effects of age, sex, puberty and weight status were assessed through hierarchical regression models.

RESULTS

There was a strong age dependency for LSM with higher values for older children, most pronounced in the upper percentiles in boys. Contrarily, CAP was relatively stable across the age span without considerable difference between boys and girls. We found a significant positive correlation between BMI-SDS and both CAP and LSM for BMI-SDS >1.28. For BMI-SDS < 1.28, the association was also positive but reached statistical significance only for CAP. Further, the association between BMI-SDS and CAP was significantly stronger in younger than in older children. There was no association between pubertal status and CAP. For LSM, we found that children with a high BMI-SDS but not children with normal weight had significantly higher LSM values in Tanner stage 4.

CONCLUSIONS

Age, sex, pubertal status and weight status should be considered when interpreting LSM and CAP in pediatric patients to facilitate and improve early detection of abnormal liver function, which is associated with common pathologies, such as NAFLD.

Performance of shear wave elastography: A single centre pilot study of mixed etiology liver disease patients with normal BMI

Purpose

To assess the performance of shear wave ultrasound elastography (SWE) for non-invasive grading of fibrosis in normal BMI patients with varied aetiology chronic liver disease.

Method

Prospective SWE liver and spleen stiffness (LS, SS respectively) of 124 patients (94 men, mean age 45.4 ± 12.4 years, mean BMI 19.66 ± 1.49) with CLD of mixed aetiology, who underwent liver biopsy, between January 2019-20 was analysed using receiver operating curve (ROC) and classification analysis regression tree (CART) to determine fibrosis cut-off values and nominal logistical regression to quantify fibrosis.

Results

Of 124 patients, 50 (40%) had non-alcoholic steatohepatitis (NASH), 31 (25%) chronic hepatitis B (CHB) and 43 (35%) alcoholic liver disease (ALD) on biopsy. Overall mean LS and SS of the study population was 11.81 ± 5.9 and 16.88 ± 10.8 kPa, respectively. LS cut-off value <8 kPa was consistent with F0, 9-14 kPa for F1-F2 and >14.9 kPa for F3-F4 fibrosis on biopsy. On application of CART, LS value < 5.3 kPa was discriminative for NASH, 5.32 to <12.64 kPa for CHB, >12.64 kPa for ALD, SS <15.3 kPa was discriminative for NASH, 15.3-30 kPa for CHB and >30 kPa for ALD in our study population.

Conclusion

SWE is a viable non-invasive tool for assessment of liver fibrosis grading in a population of mixed aetiology CLD. LS values in conjunction with SS are promising predictors of F2-F3 fibrosis with potential to discriminate select categories like CHB and NASH in such a population.

Can ultrasound elastography assess liver quality in brain-dead donors and predict early allograft dysfunction after transplantation?

PURPOSE

To evaluate the role of two-dimensional shear wave elastography (2D SWE) in assessing graft quality before liver transplantation and the relationship between donor liver stiffness (LS) and early allograft dysfunction (EAD) after transplantation.

METHODS

Eighty-three donors from January 2018 to December 2018 were involved in this prospective study. Liver stiffness measurements (LSMs) were performed using 2D SWE. The differences in LS values between discarded and transplanted grafts were analyzed. The relationship of donor LS with recipient EAD was also evaluated.

RESULTS

Our results suggest that the donor LS values were higher in discarded grafts than in transplanted grafts (24.0 ± 10.9 kPa vs 10.0 ± 2.6 kPa, p < 0.001). LSM failed in one donor. According to multivariate logistic regression analysis, the donor LS values ≥10.9 kPa (odds ratio [OR] 4.042, 95% confidence interval [CI] 1.133-14.421, p = 0.031), BMI (OR 1.287, 95% CI 1.025-1.616, p = 0.030) and INR (OR 6.703, 95% CI 1.338-33.589, p = 0.021) were independently associated with EAD.

CONCLUSION

Donor LSM conducted by 2D SWE might represent an effective quantitative method to evaluate graft quality. Donor LS might predict recipient EAD after liver transplantation.

Effect of Q-Box size on liver stiffness measurement by two-dimensional shear wave elastography

PURPOSE

To investigate the effect of the Q-Box size on liver stiffness (LS) measurement by two-dimensional shear wave elastography (2D SWE).

METHODS

Ninety-eight patients with chronic liver disease were enrolled. Each patient was continuously measured five times. The Q-Box diameter was adjusted to 10, 20, and 30 mm each time. The liver stiffness values (LSVs) at different diameters were compared in the following groups: LSVs ≤6.2 kPa, 6.2 kPa < LSVs ≤11 kPa, LSVs >11 kPa. The reliability and repeatability of LS measurement at different diameters were evaluated.

RESULTS

The differences in LSVs at different Q-Box diameters were statistically significant only when LSV ≤6.2 kPa (p = 0.004). There were no statistically significant differences in standard deviation (SD), SD/median, coefficient of variation (CV), and interquartile range (IQR)/median at different Q-Box diameters (p > 0.05). There were statistical differences in minimum LSVs and percentage of minimum LSVs ≤0.2 kPa as well as in stability index (SI) and percentage of SI <90% at different Q-Box diameters (p < 0.05). The intraclass correlation coefficients (ICCs) were up to 0.98 at Q-Box diameters of 10, 20, and 30 mm.

CONCLUSIONS

Our study showed that Q-Box size may lead to significant differences in LSVs, especially when LSVs ≤6.2 kPa. The Q-Box size had a large effect on the reliability of a single LS measurement but did not affect the repeatability of multiple measurements.

Shear wave elastography evaluation of liver, pancreas, spleen and kidneys in patients with familial mediterranean fever and amyloidosis

OBJECTIVES

Amyloid deposits in a visceral organ can contribute to tissue stiffness that could be measured with shear wave elastography (SWE). We aimed to investigate changes in organ stiffness in conjunction with laboratory parameters in patients with Familial Mediterranean Fever (FMF) and amyloidosis.

METHODS

This prospective study included 27 FMF patients, 11 patients with amyloidosis, and 38 healthy controls. Median shear wave elasticity values of the liver, spleen, both kidneys, and pancreas on SWE were compared among study and control groups. The mean values of CRP (C-reactive protein) and ESR (erythrocyte sedimentation rate) were compared by the t-test and the median of SAA (serum amyloid A protein) was compared with the Mann-Whitney U test between FMF groups with and without amyloidosis. Spearman's correlation analysis was performed to reveal the association between stiffness values and laboratory parameters.

RESULTS

The median liver, spleen, kidney, and pancreas elasticity values were significantly higher in the FMF group with amyloidosis compared to control subjects. The median kidney stiffness values in the FMF group with or without amyloidosis were significantly higher compared to control subjects. Median liver stiffness values in FMF patients with amyloidosis were significantly higher than FMF patients without amyloidosis. There were statistically significant positive correlations between the CRP (p = 0.001, r = 0.56), ESR (p = 0.001, r = 0.61), and SAA (p = 0.002, r = 0.53) levels with spleen stiffness, and CRP (p = 0.006, r = 0.48) and ESR (p = 0.001,r = 0.61) levels with pancreas stiffness, and ESR (p = 0.004, r = 0.51) levels with the left kidney stiffness.

CONCLUSION

SWE could be a potential tool for noninvasive follow-up of FMF patients and also amyloid deposition.

ADVANCES IN KNOWLEDGE

Both acute inflammation and amyloidosis in the FMF patients could increase organ stiffness.

Association of shear-wave elastography with clinical outcomes post-liver transplantation

PURPOSE

Two-dimensional shear-wave elastography (2D-SWE) assessment of liver stiffness has the advantage of being obtained during conventional ultrasound. Liver-stiffness values on 2D-SWE for grafted livers are unknown, as are their potential link to post-transplantation morbidity. This study was undertaken to determine liver-stiffness values on 2D-SWE for grafted livers without complications, and examine relationships between liver-stiffness values on 2D-SWE and early post-operative arterial or biliary complications.

METHODS

In our facility, all liver-transplant recipients are entered in a comprehensive surgical database, where donor, procedure and recipient characteristics are described. All patients underwent systematic 2D-SWE assessment. Potential relationships were analyzed between liver-stiffness findings and donor, procedure and recipient characteristics, and follow-up events, including death, arterial or biliary complications, graft removal and allograft-dysfunction scores.

RESULTS

Liver-stiffness values on 2D-SWE of 337 ultrasound examinations from 165 liver-transplant recipients were collected retrospectively. Median time from transplantation to 2D-SWE examination was 149 days, with median follow-up at 36 months. The mean±SD stiffness value for grafts without complications was 7.3±2.3kPa; it was significantly higher during the first 90 days (8.2±2.5kPa) post-transplant than after 1year (7.0±2.4kPa) (P=0.01). Patients with biliary complications during the first-year post-transplantation had significantly higher mean liver-stiffness values on 2D-SWE than those without, respectively: 9.8±7.0 vs 7.5±1.8kPa (P=0.01).

CONCLUSIONS

Post-transplantation patients without complications had stiffer livers than the general population, with higher values during the first 90 days after surgery. Liver-stiffness values on 2D-SWE were significantly higher for patients with biliary, but not arterial, complications.

Diagnostic value of supersonic shear impulse elastography for malignant cervical lymph nodes: a Bayesian analysis

Purpose

This study aimed to assess the diagnostic performance of supersonic impulse (SSI) elastography in differentiating malignant and benign cervical lymph nodes.

Methods

The Medline, Embase, and Cochrane Central databases were searched until December 1, 2020. Two different reviewers checked the studies and extracted the data. The diagnostic yields were quantitatively synthesized using a Bayesian bivariate model with an integrated nested Laplace approximation in R.

Results

In total, 590 patients with 892 cervical lymph nodes who underwent SSI elastography were included. The total prevalence of malignancy was 33.7% (301/892), and the four elastic modulus values (mean, maximum, minimum, and standard deviation) were significantly different between malignant and benign lymph nodes. For the mean elastic modulus, the summary estimates for sensitivity and specificity were 0.720 (95% credible interval [CrI], 0.592 to 0.824) and 0.877 (95% CrI, 0.727 to 0.969), respectively. The estimated area under the curve (AUC) was 0.845 (95% CrI, 0.672 to 0.914). For the maximum elastic modulus, the sensitivity and specificity were estimated to be 0.809 (95% CrI, 0.698 to 0.899) and 0.816 (95% CrI, 0.643 to 0.924), respectively. The estimated AUC was 0.834 (95% CrI, 0.579 to 0.938). The minimum and standard deviation of the elastic modulus and the outcomes of the positive and negative likelihood ratio, diagnostic odds ratio, and risk difference were also calculated.

Conclusion

SSI elastography is an acceptable imaging technique for diagnosing malignant cervical lymph nodes, and it can play a complementary role today. Both maximum and mean elastic modulus values should be taken into consideration to make a clinical judgment.

Cryogel-Integrated Biochip for Liver Tissue Engineering

Microfluidic systems and polymer hydrogels have been widely developed for tissue engineering. Yet, only a few tools combining both approaches, especially for in vitro liver models, are being explored. In this study, an alginate-based cryogel-integrated biochip was engineered for dynamic hepatoma cell line culture in three dimensions (3D). The alginate cryogel was covalently cross-linked in the biochip at subzero temperatures (T < 0 °C) to create a scaffold with high mechanical stability and an interconnected macroporous network. By varying the alginate concentration and the cross-linker ratio, Young's modulus of the cryogel can be fine-tuned between 1.5 and 29 kPa, corresponding to the range of stiffness of the different physiological states of the liver. We demonstrated that HepG2/C3A cells can be cultured and maintained as viable under dynamic conditions in this device up to 6 days. Albumin synthesis and glucose consumption increased over the cell culture days. Moreover, a 3D cell structure was observed across the entire height of the biochip, which was preserved following alginate lyase treatment to remove the cryogel-based scaffold. In summary, these results represent a proof of concept of an interesting cell culture technology that should be further investigated to engineer healthy and cirrhotic liver models.

Liver stiffness as measured by two-dimensional shear wave elastography overestimates the stage of fibrosis in patients with chronic hepatitis B and hepatic steatosis

Two-dimensional shear wave elastography (2D-SWE) is a non-invasive technique for measuring liver stiffness (LS) and is used to assess the degree of hepatic fibrosis in patients with chronic hepatitis B (CHB). Despite its usefulness, several factors, other than hepatic fibrosis, can affect its diagnostic accuracy. Hepatic steatosis (HS) is a common lesion in CHB that has increasingly been getting attention in the field of disease development; however, its influence on the measurement of LS remains unclear. We aimed to determine whether HS affects the diagnostic accuracy of 2D-SWE in patients with CHB. Serum parameters and LS values were obtained from 161 patients with CHB. The degrees of hepatic fibrosis and inflammatory activity were estimated based on the METAVIR Cooperative Study Group criteria, and the extent of HS was defined as the percentage of hepatocytes containing fat droplets using oil red staining. We found that LS values were independently correlated with HS in the early stages of hepatic fibrosis (F0-F2 or F0-3). Furthermore, LS values in patients with significant steatosis (S≥10%) were higher than the counterpart in fibrosis stages F0-2 (6.82±1.57 vs. 7.92±1.99; p=0.010) and F0-3 (7.18±1.84 vs. 8.25±1.91; p=0.007). Therefore, false positive rates (FPRs) in the diagnosis of advanced fibrosis (16.00% vs. 37.04%, p=0.037) and cirrhosis (6.67% vs. 21.62%, p=0.030) were higher in patients with significant steatosis. In conclusion, the use of 2D-SWE in the measurement of LS overestimates the stage of hepatic fibrosis in CHB patients with HS>10%. This should be taken into consideration to combine LS results with other non-invasive parameters to improve its accuracy.

Ultrasound-based liver elastography: current results and future perspectives

Chronic liver disease affects 185 million population worldwide. It encompasses a heterogenous disease spectrum, but all can lead to the development of liver fibrosis. The degree of liver fibrosis is not only a prognosticator, but has also been used to guide the treatment strategy and to evaluate treatment response. Traditionally, staging of liver fibrosis is determined on histological analysis using samples obtained from an invasive liver biopsy. Ultrasound-based liver elastography is a non-invasive method of assessing diffuse liver disease in patients with known chronic liver disease. The use of liver elastography has led to a significant reduction in the number of liver biopsies performed to assess the severity of liver fibrosis and a liver biopsy is now reserved for only select sub-groups of patients. The aim of this review article is to discuss the key findings and current evidence for ultrasound-based elastography in diffuse liver disease as well as the technical challenges and to evaluate the potential research direction.

Technical Performance of Two-Dimensional Shear Wave Elastography for Measuring Liver Stiffness: A Systematic Review and Meta-Analysis

Objective

To assess the technical performance of two-dimensional shear wave elastography (2D-SWE) for measuring liver stiffness.

Materials and Methods

The Ovid-MEDLINE and EMBASE databases were searched for studies reporting the technical performance of 2D-SWE, including concerns with technical failures, unreliable measurements, interobserver reliability, and/or intraobserver reliability, published until June 30, 2018. The pooled proportion of technical failure and unreliable measurements was calculated using meta-analytic pooling via the random-effects model and inverse variance method for calculating weights. Subgroup analyses were performed to explore potential causes of heterogeneity. The pooled intraclass correlation coefficients (ICCs) for interobserver and intraobserver reliability were calculated using the Hedges-Olkin method with Fisher's Z transformation of the correlation coefficient.

Results

The search yielded 34 articles. From 20 2D-SWE studies including 6196 patients, the pooled proportion of technical failure was 2.3% (95% confidence interval [CI], 1.3–3.9%). The pooled proportion of unreliable measurements from 20 studies including 6961 patients was 7.5% (95% CI, 4.7–11.7%). In the subgroup analyses, studies conducting more than three measurements showed fewer unreliable measurements than did those with three measurements or less, but no intergroup difference was found in technical failure. The pooled ICCs for interobserver reliability (from 10 studies including 517 patients) and intraobserver reliability (from 7 studies including 679 patients) were 0.87 (95% CI, 0.82–0.90) and 0.93 (95% CI, 0.89–0.95), respectively, suggesting good to excellent reliability.

Conclusion

2D-SWE shows good technical performance for assessing liver stiffness, with high technical success and reliability. Future studies should establish the quality criteria and optimal number of measurements.

Reference values of normal liver stiffness in healthy children by two methods: 2D shear wave and transient elastography

TE and 2D-SWE are well-documented in studies performed on adults, but those on pediatric patients are limited. The aim of this study was to establish pediatric reference values for liver stiffness using two elastography methods: 2D-SWE and TE. We performed an observational study on 206 healthy children. All children underwent anamnesis, clinical exam, laboratory tests, US exam, TE and 2D-SWE for liver stiffness assessment. The mean liver stiffness value by 2D-SWE for all children was 3.72 ± 0.48 kPa. The mean values ranged between 3.603 ± 0.2678 kPa (3–5 years of age) and 3.774 ± 0.4038 kPa (9–11 years). The reference values varied between 4.1386 kPa (3–5 years of age) and 4.88 kPa (12–15 years). The mean liver stiffness value by TE was 3.797 ± 0.4859 kPa. The values ranged between 3.638 ± 0.4088 kPa (6–8 years of age) and 3.961 ± 0.5695 kPa (15–18 years). The cutoff values varied from 4.4064 kPa (3–5 years of age) to 5.1 kPa (15–18 years). We found a significant positive correlation between E Median values by TE and age [95% CI: 0.1160 to 0.3798, r = 0.2526, p = 0.0002]. Our findings revealed that the mean values of liver stiffness for all children on 2D-SWE and TE were almost identical, 3.72 ± 0.48 kPa versus 3.797 ± 0.4859 kPa.

Does Operator Experience and the Q-Box Diameter Affect the Repeatability of Liver Stiffness Measurements Obtained by 2-Dimensional Shear Wave Elastography?

OBJECTIVES

The purpose of this research was to evaluate whether operator experience and the quantitative analysis system (Q-Box; SuperSonic Imagine, Aix-en-Provence, France) diameter affect the repeatability of liver stiffness measurements.

METHODS

We enrolled 417 outpatients. All measurements were performed by 2 operators, including an expert and a novice. Each patient was continuously measured 3 times by the 2 operators. The Q-Box diameter was adjusted to 10, 20, and 30 mm each time, and the mean elasticity values were recorded. Intraobserver repeatability was evaluated by the intraclass correlation coefficient (ICC). Interobserver repeatability was evaluated by the ICC, coefficient of variation (CV), and Bland-Altman plots.

RESULTS

The study group included 241 male and 176 female patients. The expert operator had higher ICCs than the novice operator at each Q-Box diameter. The overall interobserver agreement was excellent, and the results showed that compared to other groups, the ICC was the lowest and the CV was the largest for the 30-mm-diameter group. The ICC and CV values were similar between the 10- and 20 mm-diameter groups. The Bland-Altman plots showed that the mean difference was -0.2 kPa for the 10-, 20-, and 30 mm-diameter groups. However, the limits of agreement were the largest in the 30-mm-diameter group and were similar between the 10- and 20-mm-diameter groups.

CONCLUSIONS

The repeatability of liver stiffness measurements is affected not only by experience but also by the Q-Box diameter.

Precise fibrosis staging with shear wave elastography in chronic hepatitis B depends on liver inflammation and steatosis

BACKGROUND

Two-dimensional shear wave elastography (2D-SWE) is the latest generation of ultrasound elastography for the non-invasive assessment of liver fibrosis in chronic hepatitis B (CHB). We aimed to identify confounders of 2D-SWE in fibrosis grading.

METHODS

A prospective cohort of 440 CHB patients (286 with liver biopsy and 154 with clinical decompensated cirrhosis) was consecutively enrolled from a clinical trial (registration number: ChiCTR-DCD-15006000) aimed at optimizing 2D-SWE assessments from 2015 to 2018. All patients underwent 2D-SWE examination, anthropometric measurement, and serum biomarker assessment. Steatosis was graded by the magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF).

RESULTS

Overall, the prevalence of incorrect fibrosis staging by 2D-SWE was 26.1% (n = 115), with 43.5% of patients under-staged and 56.5% over-staged. In multivariate analysis, the steatosis degree was an independent predictor of 2D-SWE discordance in the overall cohort, with moderate-severe steatosis for underestimation (odds ratio, [OR] = 4.3, 95% confidence interval [CI] 1.2-18.2, p = 0.049) and overestimation (OR = 8.2, 95% CI 2.9-23.5, p < 0.001), and mild steatosis for overestimation (OR = 3.7, 95% CI 1.5-9.0, p = 0.004). In patients with liver biopsy, both histological inflammation activity over 2 (OR = 5.0, 95% CI 2.0-25.3, p = 0.048) and moderate-severe steatosis (OR = 5.2, 95% CI 2.1-13.4, p < 0.001) were independent factors associated with discordance. For the risk of 2D-SWE mis-staging, a nomogram that integrated these confounders was established and the area under the receiver operating characteristic curve of the model was 0.861.

CONCLUSIONS

Steatosis and inflammation activities were confounders for 2D-SWE. The combination of these confounders could predict mis-staging risks of CHB-related fibrosis with 2D-SWE and may be valuable to decision-making on liver biopsy for fibrosis staging.

Ultrasound-based liver elastography in the assessment of fibrosis

Ultrasound-based elastography has rapidly replaced the need for liver biopsy in most patients with chronic liver disease in recent years. The technique is now widely supported by many manufacturers. This review will introduce various current ultrasound-based elastography techniques, review the physics and scanning techniques, discuss potential cofounding factors as well as summarising the evidence for its use in staging liver fibrosis using shear-wave elastography among different disease aetiologies. Future challenges and directions will be also be discussed.

Quantification of hepatic steatosis with ultrasound: promising role of attenuation imaging coefficient in a biopsy-proven cohort

OBJECTIVES

To prospectively assess the role of the US attenuation imaging coefficient (AC) for the diagnosis and quantification of hepatic steatosis.

METHODS

One hundred and one patients underwent liver biopsy and US-AC measurement on the same day. Liver steatosis was graded according to biopsy as absent (S0 < 5%), mild (S1 5-33%), moderate (S2 33-66%), or severe (S3 > 66%); liver fibrosis was graded from F0 to F4. The correlation between AC and steatosis on pathology (%) was calculated using the Pearson correlation coefficient. The Student t or Mann-Whitney U test was used to compare continuous variables and ROC curve analysis was used to assess diagnostic performance of AC in diagnosing steatosis.

RESULTS

Overall, 43 (42%), 35 (35%), 12 (12%), and 11 (11%) patients were classified as S0, S1, S2, and S3, respectively. The AC was positively correlated with steatosis as a continuous variable (%) on pathology (r = 0.58, p < 0.01). Patients with steatosis of any grade had a higher AC than those without steatosis (mean 0.77 ± 0.13 vs. 0.63 ± 0.09 dB/cm/MHz, respectively; p < 0.01, AUROC = 0.805). Patients with S2-S3 had a higher AC than patients with S0-1 (0.85 ± 0.11 vs. 0.67 ± 0.11 dB/cm/MHz, respectively; p < 0.01, AUROC = 0.892). AC > 0.69 dB/cm/MHz had a sensitivity and specificity of 76% and 86%, respectively, for diagnosing any grade of steatosis (S1-S3), and AC > 0.72 dB/cm/MHz had a sensitivity and specificity of 96% and 74%, respectively, for diagnosing S2-S3. The presence of advanced fibrosis (F3-F4) did not affect the calculated AC.

CONCLUSIONS

The attenuation imaging coefficient is a promising quantitative technique for the non-invasive diagnosis and quantification of hepatic steatosis.

KEY POINTS

• Measurement of the attenuation coefficient is achieved with a very high rate of technical success. • We found a significant positive correlation between the attenuation coefficient and the grade of steatosis on pathology. • The attenuation imaging coefficient is a promising quantitative technique for the noninvasive diagnosis and quantification of hepatic steatosis.

Accuracy and precision of ultrasound shear wave elasticity measurements according to target elasticity and acquisition depth: A phantom study

OBJECTIVE

To investigate the accuracy and precision of ultrasound shear wave elasticity measurements as a function of target elasticity and acquisition depth.

MATERIALS AND METHODS

Using five ultrasound systems (VTQ, VTIQ, EPIQ 5, Aixplorer, and Aplio 500), two operators independently measured shear wave elasticities in two phantoms containing five different target elasticities (8±3, 14±4, 25±6, 45±8, and 80±12 kPa) at depths of 15, 30, 35, and 60 mm. Accuracy was assessed by evaluating measurement errors and the proportions of outliers, while factors affecting accuracy were assessed using logistic regression analysis. Measurement errors were defined as differences between the measured values and 1) the margins of the target elasticity, and 2) the median values of the target elasticity. Outliers were defined as measured values outside the margins of the target elasticity. Precision was assessed by calculating the reproducibility of measurements using the within-subject coefficient of variation (wCV).

RESULTS

Mean measurement errors and the proportions of outliers were higher for high than for low target elasticities (p<0.001), but did not differ in relation to acquisition depth, either within an elastography system or across the different systems. Logistic regression analysis showed that target elasticity (p<0.001) significantly affected accuracy, whereas acquisition depth (p>0.05) did not. The wCV for the 80±12 kPa target (31.33%) was significantly higher than that for lower elasticity targets (6.96-10.43 kPa; p<0.001). The wCV did not differ across acquisition depths. The individual elastography systems showed consistent results.

CONCLUSIONS

Targets with high elasticity showed lower accuracy and lower precision than targets with low elasticity, while acquisition depth did not show consistent patterns in either accuracy or precision.

Liver Stiffness Measured by 2-Dimensional Shear Wave Elastography: Prospective Evaluation of Healthy Volunteers and Patients With Liver Cirrhosis

OBJECTIVES

We aimed to establish normal values for liver stiffness measurement, performed by 2-dimensional shear wave elastography (LOGIQ E9; GE Healthcare, Wauwatosa, WI), in healthy volunteers, patients with nonhepatic morbidities, and patients with histologically confirmed liver cirrhosis.

METHODS

A total of 175 participants were included between July 2016 and February 2018. Three cohorts were analyzed: healthy volunteers (n = 68), patients with healthy livers but nonhepatic morbidities (n = 57), and patients with liver cirrhosis (n = 50). Liver stiffness measurement was performed by 2 observers with different levels of experience to determine interobserver agreement.

RESULTS

Of the 175 participants included, 91 were male, and the mean age ± SD was 44.4 ± 19.4 years. The success rate for 175 liver stiffness measurements was 95.4%. The number of unsuccessful measurements was significantly higher in the liver cirrhosis cohort (P = .04). The interobserver agreement was excellent (intraclass correlation coefficient, 0.87). Liver stiffness in the healthy-liver patient cohort (4.93 ± 0.83 kPa) was not significantly different from that in the healthy-volunteer cohort (5.19 ± 1.03 kPa; P = .13). Apart from male sex in the healthy-volunteer cohort, age, body mass index, mild steatosis, and nonhepatic morbidities had no significant impact on liver stiffness. Liver stiffness values in participants without liver disease (healthy volunteers and healthy-liver patients; n = 125) ranged from 3.62 to 7.02 kPa (2.5th-97.5th percentiles). Notably, there was no overlap of liver stiffness measurements between the patients without liver disease and the cirrhosis cohort (13.29 ± 3.27 kPa [7.76-19.49 kPa]).

CONCLUSIONS

Liver stiffness values in healthy individuals vary widely and are not dependent on age, body mass index, or specific nonhepatic comorbidities. Liver stiffness values within the normal range can noninvasively rule out cirrhosis, as liver stiffness is significantly higher in cirrhotic patients (P < .001). Two-dimensional shear wave elastography has excellent interobserver agreement.

Performance of two--dimensional ultrasound shear wave elastography: reference values of normal liver stiffness in children

BACKGROUND

Two-dimensional (2-D) shear wave elastography is a new sonographic elastography method for noninvasive measurement of liver stiffness.

OBJECTIVE

The aim of this study was to establish reference values of normal liver stiffness on 2-D shear wave elastography in children.

MATERIALS AND METHODS

Two-dimensional shear wave elastography values were measured in 202 children with no liver disease from the neonatal period to puberty, who were divided into 4 age groups: newborns and infants, preschoolers, elementary school children and adolescents. We investigated the effects of age, depth of elastography measurement, transducer, number of measurements per child, liver size and Doppler parameters of hepatic blood flow on liver elasticity values.

RESULTS

The mean normal liver elasticity value in the study population was: 4.29±0.59  kilopascals (kPa). In neonates and infants, mean liver elasticity value was 4.63 (± 0.6) kPa, in preschoolers and elementary school children, 4.05 (± 0.57) kPa and 4.15 (± 0.52) kPa, respectively, and in adolescents, 4.39 (± 0.55) kPa. Values in neonates and infants as well as adolescents were significantly higher than in preschoolers and elementary school children (Kruskal-Wallis, P<0.001; Mann-Whitney U tests, P<0.05). There was no significant association between liver elasticity values and size of the right lobe or Doppler parameters of hepatic blood flow. Different depths and the number of elastography measurements had no effect on liver elasticity values.

CONCLUSION

Two-dimensional shear wave elastography is achievable in a wide range of age in children. We established the reference values of normal liver stiffness on 2-D shear wave elastography in children.

Role of two-dimensional shear wave elastography in chronic liver diseases: A narrative review

Liver biopsy is the gold standard for evaluating the degree of liver fibrosis in patients with chronic liver disease. However, due to the many limitations of liver biopsy, there has been much interest in the use of noninvasive techniques for this purpose. Among these techniques real-time two-dimensional shear wave elastography (2D-SWE) has the advantage of measuring tissue elasticity with the guidance of B-mode images. Recently, many studies have been conducted on the application of 2D-SWE in patients with various liver diseases, and their validity has been confirmed. Here, we briefly discuss the role of 2D-SWE in patients with chronic liver diseases, particularly aspects of the examination techniques and clinical applications.

Clinical utilization of shear wave elastography in the musculoskeletal system

Shear wave elastography (SWE) is an emerging technology that provides information about the inherent elasticity of tissues by producing an acoustic radiofrequency force impulse, sometimes called an "acoustic wind," which generates transversely-oriented shear waves that propagate through the surrounding tissue and provide biomechanical information about tissue quality. Although SWE has the potential to revolutionize bone and joint imaging, its clinical application has been hindered by technical and artifactual challenges. Many of the stumbling blocks encountered during musculoskeletal SWE imaging are readily recognizable and can be overcome, but progressive advances in technology and a better understanding of image acquisition are required before SWE can reliably be used in musculoskeletal imaging.

Value of Two-Dimensional Shear Wave Elastography for Assessing Acute Liver Congestion in a Bama Mini-Pig Model

BACKGROUND

To date, liver congestion is one of the most significant clinical diseases. However, few studies have profoundly investigated the development, pathology, and prognosis of the important problems associated with acute hepatic congestion.

AIMS

To explore the value of noninvasive two-dimensional shear wave elastography (2D-SWE) for assessing acute liver congestion in an animal model.

METHODS

Six healthy Bama mini-pigs were used for this research and randomly divided into the experimental group and control group. We measured the basal liver stiffness (LS) by 2D-SWE and then clamped the inferior vena cava (IVC). LS was measured after 1, 5, 10, and 15 min. We reopened the IVC of experimental group pigs and detected the LS again. All pigs were killed and obtained for a pathological microscopic examination.

RESULTS

LS was distinctly increased from 7.03 ± 0.48 to 17.18 ± 3.40 kPa (p < 0.01) within 15 min and reversed to almost normal values of 7.59 ± 0.77 kPa (p < 0.01) within 5 min. In addition, two-dimensional ultrasound images demonstrated the interesting phenomenon of spontaneous echo contrast. Most importantly, the pathologic results of experimental group pigs showed the central veins of the hepatic lobules and hepatic sinusoids were enlarged and filled with numerous erythrocytes; central lobular hepatocytic necrosis and edema were noted.

CONCLUSIONS

In conclusion, 2D-SWE is a valuable, reliable, and quantitative approach to successfully assess acute liver congestion, and it is well consistent with histopathological characteristics. Besides, acute liver congestion is an important factor influencing LS that increases LS in a reversible way.

Real-time shear wave elastography (SWE) assessment of short- and long-term treatment outcome in Budd-Chiari syndrome: A pilot study

Purpose

The first aim of this study was to analyze the relationships between liver stiffness measurement, hepatic venous pressure and liver fibrosis. The second aim was to demonstrate the utility of real-time shear wave elastography for evaluation of Budd-Chiari syndrome patients before and after balloon hepatic venous angioplasty.

Materials and methods

A total of 32 patients with Budd-Chiari syndrome slated for successful balloon angioplasty met the inclusion and exclusion criteria. Shear wave elastography was used to generate dynamic liver stiffness measurement 2 days before angioplasty and 2 days, 3 months, and 6 months after angioplasty. Hepatic venous pressures were measured during balloon angioplasty. Correlations among liver stiffness, hepatic venous pressure, and fibrosis were assessed.

Result

Mean liver stiffness was 35.17 ± 10.60 kPa, 20.15 ± 5.47 kPa, 15.36 ± 4.34 kPa and 15.68 ± 5.58 kPa at baseline and 2 days, 3 months, and 6 months after angioplasty, respectively. Liver stiffness measured at 2 days and 3 months after angioplasty was significantly decreased (P < 0.001); liver stiffness measured at 6 months after angioplasty was not significantly different from that measured at 3 months after angioplasty (P = 0.636). Analysis of liver stiffness measurement and hepatic venous pressure before balloon angioplasty yielded a coefficient of correlation r = 0.701 (P < 0.001). Before and 2d after angioplasty, liver stiffness measurement did not correlated with fibrosis (r = − 0.170, P = 0.22), (r = 0.223, P = 0.220), respectively, while the LSM difference before and 2 days after angioplasty negatively correlated with stiffness severity (r = − 0.502, P = 0.003). Liver stiffness measured at 2 days and 3 months after angioplasty was significantly decreased (P < 0.001), remaining stable at 3 months, though still in the cirrhotic range.

Conclusions

The liver stiffness of Budd-Chiari syndrome patients, measured by shear wave elastography, decreased considerably after hepatic venous recanalization, and significantly correlated with hepatic venous pressure though not with degree of fibrosis. Shear wave elastography may be effective in monitoring short- and long-term treatment outcomes in Budd-Chiari syndrome.

Shear Wave Elastography as a Quantitative Biomarker of Clinically Significant Portal Hypertension: A Systematic Review and Meta-Analysis

OBJECTIVE

To qualify shear wave elastography (SWE) as a biomarker for clinically significant portal hypertension (CSPH) beyond proof of concept, we aimed to accumulate and summarize the current evidence through systematic review and meta-analysis.

MATERIALS AND METHODS

A computerized literature search was performed to identify studies from MEDLINE and EMBASE up to February 9, 2017. Studies on the diagnostic performance of liver stiffness measurements using SWE for CSPH with hepatic venous pressure gradient (HVPG) as the reference standard were included. Various aspects of SWE were comprehensively assessed. The summary diagnostic performance of SWE for the diagnosis of CSPH and the summary correlation coefficient between liver stiffness measured using SWE and HVPG were evaluated through a meta-analysis.

RESULTS

Nine articles (including 746 patients) were retrieved. The diagnostic performance of SWE for the diagnosis of CSPH was fairly good, with a summary sensitivity of 85% (95% CI, 75-91%; I² = 78.56%) and summary specificity of 85% (95% CI, 77-90%; I² = 0%); the area under the ROC curve was 0.88 (95% CI, 0.85-0.91). The summary correlation coefficient between liver stiffness and HVPG measurements was 0.741 (95% CI, 0.658-0.825; I² = 0%). These results support the value of SWE as a diagnostic biomarker for CSPH. However, there was significant heterogeneity in the imaging devices, protocols, liver stiffness measurement methods, and cutoff values used, which suggests that standardization is required.

CONCLUSION

The consistent evidence favoring SWE as a biomarker for CSPH should be considered in the biomarker qualification process and management of patients with CSPH.

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

Two-dimensional shear wave elastography (2D-SWE) is a rapid, simple and novel noninvasive method that has been proposed for assessing hepatic fibrosis in patients with chronic liver diseases (CLDs) based on measurements of liver stiffness. 2D-SWE can be performed easily at the bedside or in an outpatient clinic and yields immediate results with good reproducibility. Furthermore, 2D-SWE was an efficient method for evaluating liver fibrosis in small to moderately sized clinical trials. However, the quality criteria for the staging of liver fibrosis are not yet well defined. Liver fibrosis is the main pathological basis of liver stiffness and a key step in the progression from CLD to cirrhosis; thus, the management of CLD largely depends on the extent and progression of liver fibrosis. 2D-SWE appears to be an excellent tool for the early detection of cirrhosis and may have prognostic value in this context. Because 2D-SWE has high patient acceptance, it could be useful for monitoring fibrosis progression and regression in individual cases. However, multicenter data are needed to support its use. This study reviews the current status and future perspectives of 2D-SWE for assessments of liver fibrosis and discusses the technical advantages and limitations that impact its effective and rational clinical use.

Assessing Liver Stiffness by 2-D Shear Wave Elastography in a Healthy Cohort

The aim of this study was to assess the normal ranges of liver stiffness measurements (LSMs) in participants with healthy livers, using General Electric 2-D shear wave elastography (2-D-SWE-GE) compared with transient elastography (TE). We included 80 participants with healthy livers and without known liver disease, in whom liver stiffness was evaluated in the same session using two elastographic methods, TE and 2-D-SWE-GE. Reliable LSMs were defined for TE as the median of 10 measurements with a success rate of ≥60% and an interquartile range (IQR) < 30%, and for 2-D-SWE-GE, as the median of 10 measurements acquired in a homogenous area and an IQR < 30%. Participants with LSMs > 6.5 kPa by TE were excluded. Reliable LSMs were obtained in 79 participants (98.7%) by means of 2-D-SWE-GE and in 80 participants (100%) by means of TE (p = 0.9). The mean LSM obtained by 2-D-SWE-GE in our cohort of participants with healthy livers was 5.1 ± 1.3 kPa, which was significantly higher than the LSM assessed by TE (4.3 ± 0.9 kPa, p < 0.0001). In 2-D SWE-GE, mean LSMs were significantly higher for men than for women, 5.9 ± 1.2 kPa versus 4.7 ± 1.2 kPa (p = 0.0005). In conclusion, 2-D-SWE-GE has very good feasibility (98.7%) in healthy persons. The mean LSM determined by 2-D-SWE-GE in healthy participants was 5.1 ± 1.3 kPa. LSMs obtained by means of 2-D-SWE-GE were higher than those obtained by TE in participants with healthy livers.

Supersonic shear imaging for the diagnosis of liver fibrosis and portal hypertension in liver diseases: a meta-analysis

BACKGROUND AND AIMS

The meta-analysis aimed to summarize the technical success rate of supersonic shear imaging (SSI) and to evaluate the diagnostic performance of liver and spleen stiffness measurement (LSM and SSM) with SSI for the detection of liver fibrosis, portal hypertension, and gastroesophageal varices in liver diseases.

METHODS

PubMed, EMBASE, and Cochrane Library databases were searched. Technical success rate of SSI was pooled. Area under curve (AUC), sensitivity, and specificity with corresponding 95% confidence interval (CI) were calculated.

RESULTS

Included studies regarding the diagnostic performance of SSI for liver fibrosis, portal hypertension, and esophageal varices numbered 28, 4, and 4 respectively. The pooled technical success rates of LSM and SSM were 95.3% and 75.5%, respectively. The AUC, sensitivity, and specificity of LSM/SSM for different stages of liver fibrosis were 0.85-0.94, 0.7-0.89, and 0.82-0.92, respectively. The AUC, sensitivity, and specificity of LSM were 0.84 (95%CI = 0.8-0.86), 0.79 (95%CI = 0.7-0.85), and 0.82 (95%CI = 0.72-0.88) for clinically significant portal hypertension, 0.85 (95%CI = 0.82-0.88), 0.8 (95%CI = 0.68-0.88), and 0.8 (95%CI = 0.6-0.92) for any varices, and 0.86 (95%CI = 0.83-0.89), 0.86 (95%CI = 0.76-0.92), and 0.61 (95%CI = 0.35-0.83) for high-risk varices, respectively.

CONCLUSIONS

LSM with SSI had a high diagnostic accuracy for liver fibrosis, but a moderate diagnostic accuracy for portal hypertension and esophageal varices.

Assessment of liver fibrosis in chronic hepatitis: comparison of shear wave elastography and transient elastography

PURPOSE

To evaluate the diagnostic accuracy of shear wave elastography (SWE) and transient elastography (TE) in the evaluation of liver fibrosis in chronic hepatitis B (CHB) and C (CHC) patients taking liver biopsy as gold standard.

METHODS

Ethics committee approved this prospective cross-sectional study. Between October 2012 and December 2014, consecutive CHB/CHC patients fulfilling the inclusion criteria were included-age more than 18 years, informed written consent, willing and suitable for liver biopsy. SWE, TE, and biopsy were performed the same day. Liver stiffness measurement (LSM) cut-offs for various stages of fibrosis were generated for SWE and TE. AUC, sensitivity, specificity, and positive/negative predictive values were estimated individually or in combination.

RESULTS

CH patients (n = 240, CHB 172, CHC 68), 176 males, 64 females, mean age 32.6 ± 11.6 years were enrolled. Mean LSM of patients with no histological fibrosis (F0) was 5.0 ± 0.7 and 5.1+1.4 kPa on SWE and TE, respectively. For differentiating F2 and F3-4 fibrosis on SWE, at 7.0 kPa cut-off, the sensitivity was 81.3% and specificity 77.6%. For TE, at 8.3 kPa cut-off, sensitivity was 81.8% and specificity 83.1%. For F3 vs. F4, SWE sensitivity was 83.3% and specificity 90.7%. At 14.8 kPa cut-off, TE showed similar sensitivity (83.3%) but specificity increased to 96.5%. Significant correlation between SWE and TE was observed (r = 0.33, p < 0.001). On combining SWE and TE, a drop in sensitivity with increased specificity for all stages of liver fibrosis occured.

CONCLUSION

SWE is an accurate technique for evaluating liver fibrosis. SWE compares favorably with TE especially for predicting advanced fibrosis/cirrhosis. Combining SWE and TE further improves specificity.

Diffuse Liver Diseases: Role of imaging

Nowadays, the most common imaging techniques allow to study focal liver lesions with high diagnostic accuracy but a relatively recent emerging field of interest is represented by diffuse liver disease. They include a variegated series of storage and metabolic pathologies (ie, iron overload disorders and steatosis) requiring a precise diagnosis not always possible at imaging due to the overlapping of findings at conventional ultrasound, CT, or MR studies. In recent years, several imaging tecniques and specific softwares have been developed, especially for ultrasound and MR imaging, in order to identify different parameters useful in the noninvasive recognition and follow-up of these diffuse processes involving the liver. The aim of this article is to describe the most common and useful imaging findings of the most common and uncommon diffuse liver diseases illustrating the newest imaging technologies and developments at our disposal with corresponding advantages, limitations, and pitfalls.

Real-time two-dimensional Shear-wave elastography for liver stiffness in children: Interobserver variation and effect of breathing technique

OBJECTIVES

To evaluate interobserver variation and to assess the effect of the breathing technique on liver stiffness (LS) measurement using real-time two-dimensional shear-wave elastography (2D-SWE) in children.

METHODS

Patients who underwent real-time 2D-SWE by two operators (group 1) and patients who underwent real-time 2D-SWE by one operator using the free-breathing and breath-holding techniques (group 2) were included. In group 1, interobserver agreement was assessed using the intraclass correlation coefficient (ICC) and the 95% limits-of-agreement was analyzed to evaluate the maximum change in the LS values based on Bland-Altman analysis. In group 2, the Bland-Altman plot and the paired t-test were used to determine the effect of breathing technique on LS measurement.

RESULTS

The interobserver agreement of the LS measurement in group 1 (n=63) was excellent (ICC, 0.953), and the 95% limits-of-agreement was 31.8% of the mean LS values. In group 2 (n=45), the free-breathing technique revealed systematically lower LS with a mean difference of -11.1% of the mean LS values, compared to the breath-holding technique (P=0.016).

CONCLUSION

LS measurement assessed by real-time 2D-SWE in children showed excellent interobserver agreement. Changes in LS values less than 31.8% of the mean LS values may represent the measurement error. The free-breathing technique showed lower LS values, compared to the breath-holding technique.

Reproducibility of shear wave elastography (SWE) in patients with chronic liver disease

The presence of significant fibrosis is an indicator for liver disease staging and prognosis. The aim of the study was to determine reproducibility of real-time shear wave elastography using a hepatic biopsy as the reference standard to identify patients with chronic liver disease. Forty patients with chronic liver disease and 12 normal subjects received shear wave elastography performed by skilled operators. Interoperator reproducibility was studied in 29 patients. Fibrosis was evaluated using the Metavir score. The median and range shear wave elastography values in chronic liver disease subjects were 6.15 kPa and 3.14-16.7 kPa and were 4.49 kPa and 2.92-7.32 kPa in normal subjects, respectively. With respect to fibrosis detected by liver biopsy, shear wave elastography did not change significantly between F0 and F1 (p = 0.334), F1 and F2 (p = 0.611), or F3 and F4 (0.327); a significant difference was observed between the F0-F2 and F3-F4 groups (p = 0.002). SWE also correlated with inflammatory activity (Rs = 0.443, p = 0.0023) and ALT levels (Rs = 0.287, p = 0.0804). Age, sex and body mass index did not affect shear wave elastography measurements. Using receiver operator characteristic curves, two threshold values for shear wave elastography were identified: 5.62 kPa for patients with fibrosis (≥F2; sensitivity 80%, specificity 69.4%, and accuracy 77%) and 7.04 kPa for patients with severe fibrosis (≥F3; sensitivity 88.9%, specificity 81%, and accuracy 89%). Overall interobserver agreement was excellent and was analysed using an interclass correlation coefficient (0.94; CI 0.87-0.97).This study shows that shear wave elastography executed by skilled operators can be performed on almost all chronic liver disease patients with high reproducibility. It is not influenced by age, sex or body mass index, identifies severely fibrotic patients and is also related to inflammatory activity.

Reproducibility of 2-Dimensional Shear Wave Elastography Assessment of the Liver: A Direct Comparison With Point Shear Wave Elastography in Healthy Volunteers

OBJECTIVES

Two-dimensional shear wave elastography (2D-SWE) imaging for the noninvasive assessment of tissue stiffness was assessed for reproducibility in healthy volunteers in quantifying liver elasticity, compared with an established point shear wave elastography (p-SWE) technique also known as virtual touch quantification (VTQ) (SIEMENS).

METHODS

Eleven healthy volunteers were examined by four experienced operators on two occasions, separated by two weeks (sessions A and B). Ten 2D-SWE using LOGIQ E9 and p-SWE measurements using VTQ (in meters per second) were consecutively taken from deep portions of liver segments 5 or 6 away from vascular structures, using standard techniques. Inter- and intra-observer agreement was assessed by intraclass coefficient (ICC).

RESULTS

A total of 880 2D-SWE and p-SWE velocities were recorded. Mean values from the four operators ranged between 1.188 and 1.196 m/s for 2D-SWE and 1.170 to 1.207 m/s for p-SWE. Interobserver reproducibility was good for both sessions with ICCs of 0.88 and 0.93 (2D-SWE) and 0.87 and 0.93 (p-SWE). The overall intra-operator reproducibility between sessions A and B was good for both p-SWE and 2D-SWE with ICC of 0.87 and 0.83, respectively. For inter- and intra-observer variability, the ICC was more than or equal to 0.71, indicating that the results were reliable. There was a strong and significant correlation between the 2D-SWE and p-SWE measurements (r = 0.87, P = .0006), but their velocities did not agree equally across different velocities.

CONCLUSIONS

Two-dimensional SWE using LOGIQ E9 is a reliable and reproducible method for measuring elasticity in healthy volunteers and has a similar degree of reliability as p-SWE using VTQ, but absolute measurements from the two techniques should not be used interchangeably.

Point Shear Wave Elastography in Assessment of Hepatic Fibrosis: Diagnostic Accuracy in Subjects With Native and Transplanted Livers Referred for Percutaneous Biopsy

The objective of this study was to prospectively evaluate the use of point shear wave elastography for the assessment of liver fibrosis and to determine the usefulness and optimal location for obtaining elastography measurements in native and transplanted livers. Point shear wave elastography measurements were obtained from 100 consecutive patients presenting for percutaneous liver biopsy. Measurements were acquired within both the superior right hepatic lobe (segments VII/VIII) via an intercostal approach and the inferior right hepatic lobe (segments V/VI) via a subcostal approach. Analysis of variance was used to assess statistical differences between the degree of fibrosis on percutaneous liver biopsy and elastography measurements. No statistical difference was present when comparing elastography measurements in patients with hepatic steatosis compared with patients without steatosis (P = 0.2759). There was no difference in the accuracy of elastography measurements in native livers versus transplanted livers (P = 0.221). Point shear wave elastography can accurately differentiate between patients with no-to-mild hepatic fibrosis (F0-F1) and moderate-to-severe hepatic fibrosis (≥F2) with sensitivity of 72% and specificity of 69%. Point shear wave elastography can be used as a noninvasive method to assess fibrosis in patients with native or transplanted livers. In addition, measurements can be combined or taken separately from either the superior or inferior right hepatic lobe. The presence of hepatic steatosis does not affect the accuracy of point shear wave elastography. However, shear wave elastography values in patients with body mass index greater than 40 should be interpreted with caution.