Viscoelasticity Measurement in Rat Livers Using Shear-Wave US Elastography

Ultrasound Shear Wave Elastography and Shear Wave Dispersion: Correlation with Histopathological Changes in Autoimmune Hepatitis Patients

OBJECTIVE

To evaluate the correlation between liver viscosity, as measured by shear wave dispersion (SWD), and fibrosis and inflammation in patients with autoimmune hepatitis (AIH). Additionally, to assess its potential as a non-invasive biomarker for hepatic fibrosis compared to shear wave elastography (SWE).

METHODS

This prospective study included 25 AIH patients who underwent pre-biopsy SWD and SWE measurements using the SuperSonic Mach30 system. Liver biopsy samples were assessed for fibrosis using the Scheuer grading system and for inflammation using the modified Hepatic Activity Index (mHAI). Correlations between viscosity, elastography, fibrosis, and inflammation were analysed using Spearman's correlation coefficients.

RESULTS

Viscosity demonstrated a significant correlation with fibrosis stages (Spearman's coefficient: 0.58, p = 0.002), while SWE showed a weaker correlation (Spearman's coefficient: 0.50, p = 0.01). Viscosity measurements also correlated moderately with the mHAI score (Spearman's coefficient: 0.62, p = 0.001). Subgroup analyses revealed weak to moderate correlations between viscosity and mHAI components across fibrosis stages.

CONCLUSION

Our study suggests that viscosity may be better than SWE as a non-invasive marker for assessing hepatic fibrosis in AIH, particularly in the pre-treatment period when inflammation levels are elevated. However, we could not conclusively determine the relationship between viscosity and hepatic inflammation, as a small sample size limited our findings. Further research with a larger cohort of AIH patients is necessary to better understand the correlation between viscosity and inflammation in this rare condition.

Postmortem Temporal Changes in Liver and Spleen Stiffness: Evaluation with Shear Wave Elastography in a Rat Model

Background/Objectives: Postmortem changes in tissue stiffness and organ morphology are critical for forensic medicine and pathology. Shear wave elastography (SWE) has emerged as a non-invasive tool to assess tissue stiffness, yet its potential for postmortem interval estimation remains underexplored. While previous studies have demonstrated early postmortem alterations in tissue elasticity, the temporal progression of these changes in different organs is not fully understood. This study aims to investigate the temporal changes in liver and spleen stiffness during the postmortem period using SWE and to evaluate the predictive potential of elastographic parameters for postmortem interval estimation. Methods: Twelve male Sprague-Dawley rats were sacrificed via cervical dislocation following deep anesthesia. Postmortem liver and spleen measurements, including longitudinal and short diameters and SWE values (kPa), were recorded at 0, 2, 4, 6, 9, 12, 18, 24, and 36 h. All elastographic measurements were obtained using a 5 mm circular region of interest (ROI) for the liver and a 3 mm ROI for the spleen. Changes over time were analyzed using repeated measures ANOVA, with post hoc Bonferroni corrections applied where necessary. Additionally, Receiver Operating Characteristic (ROC) curve analysis and binary logistic regression analysis were performed to assess the predictive accuracy of SWE parameters in estimating postmortem time. Results: Postmortem liver and spleen stiffness exhibited a significant declining trend over time (p < 0.001, η2 = 0.749 and η2 = 0.810, respectively). Liver and spleen dimensions initially increased, reaching peak values around 6 h, followed by a gradual reduction. ROC analysis demonstrated that spleen SWE (AUC = 0.917) and liver SWE (AUC = 0.845) were the strongest predictors of early postmortem time. Binary logistic regression further confirmed that liver and spleen SWE were statistically significant predictors of postmortem time (p = 0.006 and p = 0.020, respectively). Conclusions: This study provides evidence that postmortem liver and spleen stiffness decline progressively over time, while organ dimensions exhibit a biphasic pattern. Elastographic parameters, particularly SWE values, demonstrated strong predictive accuracy in estimating early postmortem intervals. These findings suggest that SWE may serve as a valuable imaging modality for forensic applications, providing objective insights into postmortem biomechanical changes and time-of-death estimation. Further research should explore the applicability of SWE in different tissue types and under varying environmental conditions.

Mesoporous silica nanoparticles as sensitizers: A novel approach to enhancing shear wave elastography in liver stiffness measurement

PURPOSE

The objective of this study is to elucidate the sensitizing effect of mesoporous silica nanoparticles (MSNs) on shear wave elastography (SWE) and to investigate the potential application of MSNs as a sensitizer to enhance the sensitivity of SWE in the diagnosis of metabolic-associated steatohepatitis (MASH).

MATERIALS AND METHODS

The in vitro gelatin models with varying ratios were assessed using SWE to identify the gelatin ratio that most closely approximates with human liver stiffness. Following the characterization of the dispersion properties of MSNs, in vitro models incorporating MSNs of different particle sizes were developed. The variations in shear wave velocity (SWV) within these models were measured and subjected to statistical analysis using SWE. The biocompatibility of the MSNs was evaluated, and the MSN solution was subsequently administered into a MASH animal model. The sensitizing effect of SWE on rat liver was then analyzed statistically.

RESULTS

The in vitro model demonstrated that MSNs with smaller particle sizes (100 nm and 200 nm) facilitated the propagation of SWV, thereby enhancing the sensitivity of SWE (P < 0.05). Additionally, the cell viability and hemolysis ratio of 100 nm MSNs were superior to those of 200 nm MSNs (P < 0.05). In vivo animal model experiments indicated that 100 nm fluorescence-modified MSNs could penetrate the MASH liver and elevate the liver stiffness value as measured by SWE.

CONCLUSION

MSNs have the potential to enhance the sensitivity of SWE in the diagnosis of MASH. This approach offers novel insights for improving the efficacy of SWE in clinical diagnostic and therapeutic applications.

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.

Vi-PLUS: Pioneering Plane-Wave Ultrasound to Assess Breast Glandular Tissue in Healthy Women-A Pilot Study

BACKGROUND/OBJECTIVES

This study pioneers the application of the ViPLUS module, utilizing plane-wave ultrasound to measure breast tissue viscosity and elasticity. The primary goal was to establish normal reference values for viscosity in healthy women. Secondary objectives included exploring correlations between breast tissue viscosity and breast density categories, hormonal influences, and menstrual cycle phases.

METHODS

A prospective study was conducted on 245 asymptomatic women. Viscosity and elasticity measurements were obtained using the ViPLUS module, ensuring high reliability with stringent quality control measures. Data were statistically analyzed to evaluate correlations and group differences.

RESULTS

The median viscosity value for normal breast parenchyma was 1.7 Pa.s, with no significant variations based on breast density, menopausal status, or menstrual cycle phase. A strong correlation (rho = 0.866, p < 0.001) was observed between elasticity and viscosity values.

CONCLUSIONS

The findings suggest that breast viscosity is consistent across diverse physiological states, indicating its potential as an independent diagnostic marker. This parameter could be pivotal in future breast cancer screening strategies, especially for younger women and those with dense breasts.

Prospective comparative diagnostic performance of quantitative ultrasound parameters for the measurement of hepatic steatosis in a biopsy-proven metabolic dysfunction associated steatotic liver disease cohort

OBJECTIVES

The aim of this study was to compare the diagnostic performance of attenuation imaging (ATI), shear wave elastography (SWE), and shear wave dispersion (SWD) for detecting and grading hepatic steatosis in patients with metabolic dysfunction associated steatotic liver disease (MASLD).

METHODS

Sixty-six patients with MASLD confirmed histopathologically and 34 healthy volunteers who were age/sex-matched were prospectively enrolled in this study. ATI, SWE, and SWD examinations were performed. Fibrosis stage, necroinflammatory activity, and steatosis grade were confirmed histopathologically. Steatosis was graded as follows: S0 (<5%); S1 (5%-32%); S2 (33%-66%) to S3 (>66%). We compared the diagnostic performance of ATI, SWE, and SWD for detecting and grading hepatic steatosis.

RESULTS

Both attenuation coefficient (AC) and SWD values were significantly different among the different hepatic steatosis, and both were correlated with hepatic steatosis. ATI had better diagnostic performance than SWD for detecting and grading hepatic steatosis. The area under the receiver operating characteristic (ROC) curve of ATI for detecting ≥S1, ≥S2, and =S3 were 0.917 (cut-off value of 0.69 dB/cm/MHz), 0.933 (cut-off value of 0.74 dB/cm/MHz), and 0.870 (cut-off value of 0.82 dB/cm/MHz), respectively. The area under the ROC curve of SWD value was 0.758 (cut-off value of 10.79 m/s/kHz), 0.685 (cut-off value of 12.64 m/s/kHz), and 0.722 (cut-off value of 13.24 m/s/kHz), respectively.

CONCLUSIONS

ATI technology is a reliable method for detecting and grading hepatic steatosis in patients with MASLD than SWE and SWD.

ADVANCES IN KNOWLEDGE

We compared the diagnostic performance of ATI, SWE, SWD for detecting and grading hepatic steatosis in patients with MASLD in order to find the best diagnostic parameters.

Shear Wave Dispersion Elastography in ALD and MASLD: Comparative Pathophysiology and Clinical Potential-A Narrative Review

Alcohol-related liver disease (ALD) is a major cause of global morbidity and mortality, progressing from steatosis to cirrhosis and hepatocellular carcinoma. While liver biopsy remains the gold standard for identifying liver disease, non-invasive methods like shear wave dispersion (SWD) elastography offer promising alternatives. This scoping review evaluates SWD's potential in the study of ALD, comparing it to metabolic dysfunction-associated steatotic liver disease (MASLD). SWD measures changes in shear wave speed in relation to liver viscosity and necroinflammation. Studies in MASLD suggest that SWD effectively correlates with fibrosis and inflammation stages, but its application in ALD remains underexplored. Both ALD and MASLD show similar inflammatory and fibrotic pathways, despite having different etiologies and histological features. This review emphasizes the necessity to identify ALD-specific SWD reference values and verify SWD's ability to improve diagnosis and disease progression. Prospective studies comparing SWD findings with histological benchmarks in ALD are essential for establishing its clinical utility. Incorporating SWD into clinical practice could revolutionize the non-invasive evaluation of ALD, offering a safer, cost-effective, and repeatable diagnostic tool.

Ultrasound viscoelastic imaging in the noninvasive quantitative assessment of chronic kidney disease

BACKGROUND

This study aims to evaluate the clinical application value of ultrasound viscoelastic imaging in noninvasive quantitative assessment of chronic kidney disease (CKD).

METHODS

A total of 332 patients with CKD and 190 healthy adults as a control group were prospectively enrolled. Before kidney biopsy, ultrasound viscoelastic imaging was performed to measure the mean stiffness value (Emean), mean viscosity coefficient (Vmean), and mean dispersion coefficient (Dmean) of the renal. CKD patients were divided into three groups based on estimated glomerular filtration rate. The differences in clinic, pathology, ultrasound image parameters between the control and patient groups, or among different CKD groups were compared. The correlation between viscoelastic parameters and pathology were analyzed.

RESULTS

Emean, Vmean, and Dmean in the control group were less than the CKD group (p < 0.05). In the identification of CKD from control groups, the area under curve of Vmean, Dmean, Emean, and combining the three parameters is 0.90, 0.79, 0.69, 0.91, respectively. Dmean and Vmean were increased with the decline of renal function (p < 0.05). Vmean and Dmean were positively correlated with white blood cell, urea, serum creatinine, and uric acid (p < 0.05). Vmean is positively correlated with interstitial fibrosis and inflammatory cell infiltration grades (p < 0.001).

CONCLUSIONS

Ultrasound viscoelastic imaging has advantages in noninvasive quantitative identification and evaluating renal function of CKD. Emean > 6.61 kPa, Vmean > 1.86 Pa·s, or Dmean > 7.51 m/s/kHz may suggest renal dysfunction. Combining Vmean, Dmean, and Emean can improve the efficiency of identifying CKD.

Quantitative Ultrasound and Ultrasound-Based Elastography for Chronic Liver Disease: Practical Guidance, From the AJR Special Series on Quantitative Imaging

Quantitative ultrasound (QUS) and ultrasound-based elastography techniques are emerging as non-invasive effective methods for assessing chronic liver disease. They are more accurate than B-mode imaging alone and more accessible than MRI as alternatives to liver biopsy. Early detection and monitoring of diffuse liver processes such as steatosis, inflammation, and fibrosis play an important role in guiding patient management. The most widely available and validated techniques are attenuation-based QUS techniques and shear-wave elastography techniques that measure shear-wave speed. Other techniques are supported by a growing body of evidence and are increasingly commercialized. This review explains general physical concepts of QUS and ultrasound-based elastography techniques for evaluating chronic liver disease. The first section describes QUS techniques relying on attenuation, backscatter, and speed of sound. The second section discusses ultrasound-based elastography techniques analyzing shear-wave speed, shear-wave dispersion, and shear-wave attenuation. With an emphasis on clinical implementation, each technique's diagnostic performance along with thresholds for various clinical applications are summarized, to provide guidance on analysis and reporting for radiologists. Measurement methods, advantages, and limitations are also discussed. The third section explores developments in quantitative contrast-enhanced and vascular ultrasound that are relevant to chronic liver disease evaluation.

Ultrasound Viscosity Imaging in Breast Lesions: A Multicenter Prospective Study

RATIONALE AND OBJECTIVES

To explore and validate the clinical value of ultrasound (US) viscosity imaging in differentiating breast lesions by combining with BI-RADS, and then comparing the diagnostic performances with BI-RADS alone.

MATERIALS AND METHODS

This multicenter, prospective study enrolled participants with breast lesions from June 2021 to November 2022. A development cohort (DC) and validation cohort (VC) were established. Using histological results as reference standard, the viscosity-related parameter with the highest area under the receiver operating curve (AUC) was selected as the optimal one. Then the original BI-RADS would upgrade or not based on the value of this parameter. Finally, the results were validated in the VC and total cohorts. In the DC, VC and total cohorts, all breast lesions were divided into the large lesion, small lesion and overall groups respectively.

RESULTS

A total of 639 participants (mean age, 46 years ± 14) with 639 breast lesions (372 benign and 267 malignant lesions) were finally enrolled in this study including 392 participants in the DC and 247 in the VC. In the DC, the optimal viscosity-related parameter in differentiating breast lesions was calculated to be A'-S2-Vmax, with the AUC of 0.88 (95% CI: 0.84, 0.91). Using > 9.97 Pa.s as the cutoff value, the BI-RADS was then modified. The AUC of modified BI-RADS significantly increased from 0.85 (95% CI: 0.81, 0.88) to 0.91 (95% CI: 0.87, 0.93), 0.85 (95% CI: 0.80, 0.89) to 0.90 (95% CI: 0.85, 0.93) and 0.85 (95% CI: 0.82, 0.87) to 0.90 (95% CI: 0.88, 0.92) in the DC, VC and total cohorts respectively (P < .05 for all).

CONCLUSION

The quantitative viscous parameters evaluated by US viscosity imaging contribute to breast cancer diagnosis when combined with BI-RADS.

In silico analysis reveals the prospects of renal anisotropy in improving chronic kidney disease detection using ultrasound shear wave elastography

Renal anisotropy is a complex property of the kidney and often poses a challenge in obtaining consistent measurements when using shear wave elastography to detect chronic kidney disease. To circumvent the challenge posed by renal anisotropy in clinical settings, a dimensionless biomarker termed the 'anisotropic ratio' was introduced to establish a correlation between changes in degree of renal anisotropy and progression of chronic kidney disease through an in silico perspective. To achieve this, an efficient model reduction approach was developed to model the anisotropic property of kidneys. Good agreement between the numerical and experimental data were obtained, as percentage errors of less than 5.5% were reported when compared against experimental phantom measurement from the literature. To demonstrate the applicability of the model to clinical measurements, the anisotropic ratio of sheep kidneys was quantified, with both numerical and derived experimental results reporting a value of .667. Analysis of the anisotropic ratio with progression of chronic kidney disease demonstrated that patients with normal kidneys would have a lower anisotropic ratio of .872 as opposed to patients suffering from renal impairment, in which the anisotropic ratio may increase to .904, as determined from this study. The findings demonstrate the potential of the anisotropic ratio in improving the detection of chronic kidney disease using shear wave elastography.

Associations Between Multiparametric US-Based Indicators and Pathological Status in Patients with Metabolic Associated Fatty Liver Disease

OBJECTIVE

Noninvasive evaluation of metabolic dysfunction-associated fatty liver disease (MAFLD) using ultrasonography holds significant clinical value. The associations between ultrasound (US)-based parameters and the pathological spectra remain unclear and controversial. This study aims to investigate the associations thoroughly.

METHODS

The participants with MAFLD undergoing liver biopsy and multiparametric ultrasonography were prospectively recruited from December 2020 to September 2022. Three US-based parameters, namely attenuation coefficient (AC), liver stiffness (LS) and dispersion slope (DS) were obtained. The relationship between these parameters and steatosis grades, inflammation grades and fibrosis stages was examined.

RESULTS

In this study with 116 participants, AC values significantly differed across distinct steatosis grades (p < 0.001), while DS and LS values varied among inflammation grades (p < 0.001) and fibrosis stages (p < 0.001). The area under the receiver operating characteristic curves (AUCs) of AC ranged from 0.82 to 0.84 for differentiating steatosis grades, while AUCs of LS ranged from 0.62 to 0.76 for distinguishing inflammation grades and 0.83-0.95 for discerning fibrosis stages. AUCs for DS ranged from 0.79 to 0.81 in discriminating inflammation grades and 0.80-0.88 for differentiating fibrosis stages. Subgroup analysis revealed that LS demonstrated different trends in inflammation grade but consistent trends in fibrosis stage across subgroups, whereas DS showed consistent trends for both inflammation grade and fibrosis stage across all subgroups.

CONCLUSION

AC values indicate the degree of hepatic steatosis but not inflammation or fibrosis. LS values are determined only by fibrosis stage and are not associated with inflammation grades. DS values are associated with both fibrosis and inflammation grades.

Potential role of two-dimensional shear wave elastography, including liver stiffness measurement and dispersion slope, for management of chronic hepatitis B

PURPOSE

This study assessed the use of liver stiffness (LS) and dispersion slope (DS) in classifying patients with chronic hepatitis B (CHB) by the necessity of antiviral treatment.

METHODS

A retrospective review examined 249 patients with CHB (male:female, 107:142; mean age, 53±14 years) between April 2018 and March 2022. Patients for whom treatment was indicated, termed group 1, exhibited either serum alanine transaminase (ALT) and aspartate aminotransferase levels not exceeding five times the upper limit of normal and LS >13 kPa, or hepatitis B virus DNA >2,000 IU/mL and ALT >40 IU/L. The remaining patients comprised group 2 (treatment not required). In subgroup analysis, patients with LS <13 kPa were further examined.

RESULTS

Overall, group 1 exhibited significantly higher LS (12.64±6.76 vs. 6.31±1.67 kPa, P<0.001) and DS (15.52±4.95 vs. 11.04±1.93 [m/s]/kHz, P<0.001) than group 2. In subgroup analysis, group 1 also demonstrated significantly higher values (LS: 8.05±2.12 vs 6.31±1.67 kPa, P<0.001, DS: 13.06±2.75 vs. 11.04±1.93 [m/s]/kHz, P<0.001). The areas under the curve (AUCs) for LS and DS in group 1 were 0.855 (95% confidence interval [CI], 0.80 to 0.90; P<0.001) and 0.810 (95% CI, 0.75 to 0.86; P<0.001), respectively. In subgroup analysis, the AUCs for LS and DS in group 1 were 0.751 (95% CI, 0.69 to 0.81; P<0.001) and 0.711 (95% CI, 0.64 to 0.77; P<0.001), respectively. Within group 1, the AUCs for LS and DS did not differ significantly (P>0.05).

CONCLUSION

LS and DS assist in classifying patients with CHB by their need for antiviral treatment.

Prognostic value of liver stiffness in patients hospitalized for acute decompensated heart failure: a meta-analysis

PURPOSE

Heart failure (HF) is a major health problem affecting millions of people worldwide. In the latest years, many efforts have been made to identify predictors of poor prognosis in these patients. The aim of this systematic review and meta-analysis was to enlighten the correlation between liver stiffness (LS), assessed by Shear Wave Elastography techniques, and HF, particularly focusing on the prognostic value of LS on cardiovascular outcomes.

METHODS

We searched the PUBMED databases (up to May 1st, 2023) for studies that enlightened the correlation between LS and cardiovascular outcomes in patients hospitalized for acute decompensated heart failure (ADHF). We performed a meta-analysis to estimate the efficacy of LS in predicting the prognosis of patients with ADHF.

RESULTS

We analyzed data from 7 studies, comprising 677 patients, that assessed the prognostic value of LS in predicting cardiovascular outcomes in patients hospitalized for ADHF. The pooled analysis showed that increased liver stiffness was associated with higher risk of adverse cardiac events (hazard ratio 1.07 [1.03, 1.12], 95% CI).

CONCLUSION

Increased LS is associated with poor prognosis in patients hospitalized for HF and might help effectively identify those patients at high risk for worse outcomes.

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.

US Markers and Necroinflammation, Steatosis, and Fibrosis in Metabolic Dysfunction-associated Steatotic Liver Disease: The iLEAD Study

Background Attenuation coefficient (AC) and shear-wave speed (SWS) are established US markers for assessing patients with metabolic dysfunction-associated steatotic liver disease (MASLD), while shear-wave dispersion slope (DS) is not. Purpose To assess the relationship between the multiparametric US imaging markers DS, AC, and SWS and liver histopathologic necroinflammation in patients with MASLD. Materials and Methods This international multicenter prospective study enrolled consecutive patients with biopsy-proven MASLD between June 2019 and March 2023. Before biopsy, all participants underwent multiparametric US, and measurements of DS, AC, and SWS were obtained. Multivariable linear regression analyses were performed to assess the association of clinical variables and imaging markers with pathologic findings. The diagnostic performance of imaging markers for determining inflammation grade, steatosis grade, and fibrosis stage was assessed using the area under the receiver operating characteristic curve (AUC). Results A total of 124 participants (mean age, 53 years ± 15 [SD]; 62 males) were evaluated. In multivariable regression, lobular inflammation was associated with DS (regression coefficient, 0.06; P = .02), alanine aminotransferase level (regression coefficient, 0.002; P = .002), and Hispanic or Latino ethnicity (regression coefficient, -0.68; P = .047), while steatosis was associated with AC (regression coefficient, 3.66; P < .001) and fibrosis was associated with SWS (regression coefficient, 2.02; P < .001) and body mass index (regression coefficient, 0.05; P = .02). DS achieved an AUC of 0.72 (95% CI: 0.63, 0.82) for identifying participants with inflammation grade A2 or higher (moderate to severe inflammation). AC showed excellent performance for identifying participants with grade S1 (mild) or higher steatosis (AUC, 0.92 [95% CI: 0.87, 0.97]), while SWS showed excellent performance for identifying participants with fibrosis stage F2 or higher (clinically significant fibrosis) (AUC, 0.91 [95% CI: 0.86, 0.96]). Of the three US markers, SWS showed the highest AUC (0.81 [95% CI: 0.74, 0.89]) for the diagnosis of metabolic dysfunction-associated steatohepatitis. Conclusion Of the three US imaging markers (DS, AC, and SWS), DS was most associated with lobular inflammation grade at histologic examination and demonstrated fair diagnostic performance in distinguishing moderate to severe lobular inflammation. ClinicalTrials.gov Identifier: NCT04012242 Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Yin in this issue.

Prediction of acute rejection in renal allografts using shear-wave dispersion slope

OBJECTIVES

To evaluate the role of shear-wave dispersion slope for predicting renal allograft dysfunction.

METHODS

We retrospectively reviewed 128 kidney transplant recipients (median age, 55 years [interquartile range, 43-62 years]; male, 68) who underwent biopsy for allograft evaluation from November 2022 to February 2023. Cortex and renal sinus fat stiffness and shear-wave dispersion slope were obtained at shear-wave elastography (SWE). Cortex-to-sinus stiffness ratio (SR) and dispersion slope ratio (DSR)-related clinical and pathologic factors were evaluated using multivariable linear regression analysis. We conducted univariate and multivariate analyses for multiparametric ultrasound (US) parameters for identifying acute rejection and calculated the area under the receiver operating curve (AUC) values.

RESULTS

Of 128 patients, 31 (24.2%) demonstrated acute rejection. The SR value did not differ between patient groups (1.21 vs. 1.20, p = 0.47). Patients with acute rejection demonstrated a higher DSR than those without rejection (1.4 vs. 1.21, p < 0.01). Interstitial fibrosis and tubular atrophy grade (IFTA; coefficient, 0.11/grade; p = 0.04) and renal transplant and biopsy interval (coefficient, 0.00007/day; p = 0.03) were SR determinant factors, whereas only IFTA grade (coefficient, 0.10/grade; p = 0.01) for DSR. Multivariate analysis revealed mean resistive index (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.02-1.14, p = 0.01) and DSR value (OR 16.0, 95% CI 3.0-85.8, p = 0.001) as independent factors for predicting acute rejection. An AUC of 0.74 for detecting acute rejection was achieved by combining the resistive index and DSR value.

CONCLUSION

Shear-wave dispersion slope obtained at SWE may help identify renal allograft dysfunction.

CLINICAL RELEVANCE STATEMENT

Acute rejection in renal allografts is a major cause of allograft failure, but noninvasive diagnosis is a challenge. Shear-wave dispersion slope can identify acute rejection non-invasively.

KEY POINTS

• The interstitial fibrosis and tubular atrophy grade was a determinant factor for stiffness ratio and shear-wave dispersion slope ratio between cortex and renal sinus fat. • Shear-wave dispersion slope ratio between cortex and renal sinus fat could identify acute rejection in renal allografts. • A shear-wave dispersion slope has a potential to reduce unnecessary renal biopsy for evaluating renal allografts.

The Effect of Steatosis on Shear-Wave Velocity and Viscoelastic Properties Related to Liver Fibrosis Progression in Rat Models

OBJECTIVE

Hepatic fibrosis has recently been evaluated using ultrasonography or magnetic resonance elastography. Although the shear wave velocity (SWV) obtained using point shear wave elastography (pSWE) provides a valuable measure of fibrosis, underlying steatosis may affect its measurement.

METHODS

Using hepatic fibrosis samples, this study evaluated the effect of steatosis on the shear wave velocity of pSWE (Vs) and viscoelastic properties (assessed by dynamic mechanical analysis) of rat liver. Fifty rats with various grades of steatosis and fibrosis underwent open abdominal in vivo Vs measurements using a commercial ultrasound scanner. The mechanical properties of hepatic tissue were also characterized under ex vivo conditions using dynamic mechanical analysis and the Zener model of viscoelasticity.

RESULTS

Fibrosis and steatosis progression influenced Vs and elasticity. The SWV computed using the Zener model and Vs showed a substantial correlation (r > 0.8). Fibrosis progression increased SWV. Steatosis was also related to SWV. Steatosis progression obscured the SWV change associated with fibrosis progression.

CONCLUSION

We conclude that steatosis progression affects the evaluation of fibrosis progression. This finding could aid discrimination of non-alcoholic steatohepatitis from non-alcoholic fatty liver disease using SWV.

Comparison of Fibroscan, Shear Wave Elastography, and Shear Wave Dispersion Measurements in Evaluating Fibrosis and Necroinflammation in Patients Who Underwent Liver Biopsy

OBJECTIVE

Our aim was to predict these stages of hepatic fibrosis and necroinflammation using measurements from two-dimensional shear wave elastography (2D-SWE), transient elastography (Fibroscan, TE), and shear wave dispersion (SWD).

MATERIALS AND METHODS

In this prospectively designed study, chronic liver patients with nonspecific etiology whose biopsy was performed for up to 1 week were included. Two-dimensional SWE, SWD, and TE measurements were performed. The METAVIR and F-ISHAK classification was used for histopathological evaluation.

RESULTS

Two-dimensional SWE and TE were considered significant for detecting hepatic fibrosis. In distinguishing ≥F2, for 2D-SWE, area under the receiver operating characteristics (AUROC) was 0.86 (confidence interval [CI], 0.75-0.96) for the cutoff value of 8.05 kPa ( P = 0.003); for TE, AUROC was 0.79 (CI, 0.65-0.94) for the cutoff value of 10.4 kPa ( P < 0.001). No significance was found for TE in distinguishing ≥F3 ( P = 0.132). However, for 2D-SWE, a cutoff value of 10.45 kPa ( P < 0.001), with AUROC = 0.87 (CI, 0.78-0.97) was determined for ≥F3. Shear wave dispersion was able to determine the presence of necroinflammation ( P = 0.016) and a cutoff value of 15.25 (meter/second)/kiloHertz ([m/s]/kHz) ( P = 0.006) and AUROC of 0.71 (CI, 0.57-0.85) were calculated for distinguishing ≥A2. In addition, a cutoff value of 17.25 (m/s)/kHz ( P = 0.023) and AUROC = 0.72 (CI, 0.51-0.93) were found to detect severe necroinflammation. The cutoff value for SWD was 15.25 (m/s)/kHz ( P = 0.013) for detecting ≥A2 in the reversible stage of fibrosis (F0, F1, and F2), and AUROC = 0.72 (CI, 0.56-0.88).

CONCLUSIONS

Two-dimensional SWE and TE measurements were significant in detecting the irreversible stage and the stage that should be treated in hepatic fibrosis noninvasively. Shear wave dispersion measurements were significant in detecting necroinflammation noninvasively.

Use of shear wave imaging with intestinal ultrasonography in patients with chronic diarrhea

OBJECTIVE

A retrospective study was designed to determine the role of shear wave elastography (SWE) and intestinal ultrasonography to differentiate between inflammatory and fibrotic bowel strictures by determining Young's modulus (E) and shear wave dispersion (SWD) and to compare its role with contrast-enhanced computed tomography (CECT) in patients with chronic diarrhea and pain abdomen.

METHODS

Seventy-six patients who had increased small bowel thickness (SBWT) >3 mm, and large bowel wall thickness (LBWT) >4 mm on intestinal ultrasonography (IUS) were evaluated in a two-step manner. The first step involved classifying patients with increased SBWT >3 mm and LBWT >4 mm by use of SWE and dispersion into three groups that is group I (fibrotic), group II (inflammatory) thickening, and group III (mixed-fibrosis and inflammatory) wall thickening. In the second step, etiological classification was done using six gray scale features of IUS that is length and degree of bowel thickening, presence of bowel stratification, Limberg grade of vascularity, status of mesenteric fat, juxta bowel status-nodes, fluid, and fistula formation to reach to a definitive diagnosis. These findings were compared with findings on CECT. Twenty-three patients had diagnosis confirmed by biopsy while 18 underwent surgery with histologic confirmation of operative findings. The sensitivity, specificity and AUROC for both modalities were compared.

RESULTS

Group I that is fibrotic group had 33 patients with fibrotic strictures of which fibrotic Crohn's disease (CD)and tuberculosis of the bowel were the dominant types followed by neoplastic and infective causes. In Group II that is inflammatory there were 32 patients with predominantly infective ileo-colitis, and ulcerative colitis patients while 11 patients were present in group III that is (mixed fibrotic and inflammatory) type of bowel wall thickening and were patients of inflammatory CD, infective ileo-colitis. The presence of length of bowel involvement, Limberg grade, mesenteric fat proliferation, and SBWT>9 mm were the statistically significant parameters on IUS which helped to reach to final diagnosis. The sensitivity and specificity of combined SWE with SWD and IUS were 100% and 99% while that of CECT was 78% and 96% respectively with AUROC of 100% and 64%.

CONCLUSION

SWI combined with IUS in a two-step manner is an accurate way to evaluate patients with chronic diarrhea who have increased SBWT and is not only able to differentiate inflammatory from fibrotic bowel wall thickening but also helps to form an etiological diagnosis.

The value of shear wave elasticity and shear wave dispersion imaging to evaluate the viscoelasticity of renal parenchyma in children with glomerular diseases

BACKGROUND

To study the value of shear wave elasticity and shear wave dispersion imaging to evaluate the viscoelasticity of renal parenchyma in children with glomerular diseases.

METHODS

Forty-three children with glomerular diseases were prospectively evaluated by shear wave elasticity (SWE) and shear wave dispersion imaging (SWD); 43 healthy volunteers served as the control group. The shear wave velocities (SWV) and the dispersion slopes were measured at the upper, middle, and lower poles of both kidneys. The analysis of mean SWV and mean dispersion slope in control and patient groups was used to further evaluate the value of SWE and SWD in the viscoelasticity of renal parenchyma in children with glomerular disease.

RESULTS

The mean SWV in children with glomerular disease was higher than that in the healthy control group (1.61 ± 0.09 m/s vs. 1.43 ± 0.07 m/s, p < 0.001). Compared with healthy group, the mean dispersion slope in children with glomerular disease was significantly increased (13.5 ± 1.39 (m/s)/kHz vs. 12.4 ± 1.40 (m/s)/kHz, p < 0.001). Correlation analysis showed absence of correlation between the SWV and dispersion slope of occult blood, serum creatinine, 24-h urine protein, blood albumin, BMI and ROI box depth of children with glomerular disease.

CONCLUSIONS

The present study shows that it is feasible to use SWE and SWD to evaluate the difference of viscoelasticity of the renal parenchyma between healthy children and those with glomerular disease.

Clinical applications of shear wave dispersion imaging for breast lesions: a pictorial essay

Shear wave dispersion (SWD) imaging is a newly developed ultrasound technology designed to evaluate the dispersion slope of shear waves, which is related to tissue viscosity. This advanced imaging technique holds potential for distinguishing malignant lesions from benign lesions and normal breast tissue. The SWD slope, as determined by shear wave elastography (SWE), could offer crucial insights into the characterization of breast lesions. This article presents SWE and SWD images of both malignant and benign breast lesions, in addition to normal breast tissue.

Significance of Shear Wave Dispersion Slope Values Before Versus After Biliary Drainage in Patients With Obstructive Jaundice: A Single-Center Prospective Observational Cohort Study

The shear wave dispersion (SWD) slope has become available in the clinical practice and is related to tissue viscosity. However, clinical evaluation using SWD was not yet performed for obstructive jaundice. We aimed to evaluate the change of SWD values between before and after biliary drainage in patients with obstructive jaundice. This prospective observational cohort study evaluated 20 patients with obstructive jaundice who underwent biliary drainage. The SWD and liver elasticity values were measured before versus after biliary drainage, comparing between days -5 and 0 (day 0), days 1 and 3 (day 2), and days 6 and 8 (day 7). The mean ± SD values of SWD measured at day 0, day 2, and day 7 were 15.3 ± 2.7, 14.2 ± 3.3, and 13.3 ± 2.4 m/s/kHz, respectively. Dispersion slope values were decreased significantly from day 0 to day 2, from day 2 to day 7, and from day 0 to day 7 ( P < 0.05). Liver elasticity levels and serum hepatobiliary enzymes were additionally decreased significantly over time after biliary drainage. The correlations between SWD and liver elasticity values were strong ( r = 0.91, P < 0.01). In conclusion, t he SWD values decreased significantly over time after biliary drainage concomitant with liver elasticity.

[Ultrasound systems for abdominal diagnostics - current methods, clinical applications and new technologies]

Abdominal ultrasound is the method of first choice in many clinical situations. Gray scale imaging (B-mode) and conventional Doppler techniques are nowadays complemented by contrast-enhanced ultrasound (CEUS), elastography, fat quantification and further technologies which allow multimodal characterization of organs and tissue structure using panoramic imaging, 3D-techniques and image fusion. The development of small portable devices augments the spectrum for sonographic diagnostics. In this review, we describe the current status of ultrasound technology based on published evidence. In addition, we provide guidance for quality assurance.

Influence of Measurement Depth and Acquisition Parameters on Shear Wave Speed and Shear Wave Dispersion in Certified Phantoms Using a Canon Aplio Clinical Ultrasound Scanner

OBJECTIVE

The aim of the work described here was to investigate the relative contribution of confounding factors on liver shear wave speed (SWS) and shear wave dispersion slope (SWDS) measurements in three certified phantoms using a Canon Aplio clinical ultrasound scanner.

METHODS

A Canon Aplio i800 i-series ultrasound system (Canon Medical Systems Corporation, Otawara, Tochigi, Japan) with i8CX1 convex array (center frequency = 4 MHz) was used to examine dependencies caused by the depth, width and height of the acquisition box (AQB), the depth and size of the region of interest (ROI), the AQB angle and the pressure of the ultrasound probe on the surface of the phantom.

RESULTS

Results revealed that depth is the most significant confounder in both SWS and SWDS measurements. AQB angle, height and width and ROI size exhibited minimal confounding effects on measurements. For SWS, the most consistent measurement depth is when the top of the AQB is placed between 2 and 4 cm, and the ROI is located between 3 and 7 cm deep. For SWDS, results indicate that measurement values significantly decrease with depth from the surface of the phantom until approximately 7 cm deep, and consequently no stable area of AQB placement or ROI depth exists.

CONCLUSION

In contrast to SWS, the same ideal acquisition depth range cannot necessarily be applied to SWDS measurements because of a significant depth dependency.

Magnetic resonance imaging and ultrasound elastography in the context of preclinical pharmacological research: significance for the 3R principles

The 3Rs principles-reduction, refinement, replacement-are at the core of preclinical research within drug discovery, which still relies to a great extent on the availability of models of disease in animals. Minimizing their distress, reducing their number as well as searching for means to replace them in experimental studies are constant objectives in this area. Due to its non-invasive character in vivo imaging supports these efforts by enabling repeated longitudinal assessments in each animal which serves as its own control, thereby enabling to reduce considerably the animal utilization in the experiments. The repetitive monitoring of pathology progression and the effects of therapy becomes feasible by assessment of quantitative biomarkers. Moreover, imaging has translational prospects by facilitating the comparison of studies performed in small rodents and humans. Also, learnings from the clinic may be potentially back-translated to preclinical settings and therefore contribute to refining animal investigations. By concentrating on activities around the application of magnetic resonance imaging (MRI) and ultrasound elastography to small rodent models of disease, we aim to illustrate how in vivo imaging contributes primarily to reduction and refinement in the context of pharmacological research.

Novel multi-parametric diagnosis of non-alcoholic fatty liver disease using ultrasonography, body mass index, and Fib-4 index

BACKGROUND

Shear wave speed (SWS), shear wave dispersion (SWD), and attenuation imaging (ATI) are new diagnostic parameters for non-alcoholic fatty liver disease. To differentiate between non-alcoholic steatohepatitis (NASH) and non-alcoholic fatty liver (NAFL), we developed a clinical index we refer to as the “NASH pentagon” consisting of the 3 abovementioned parameters, body mass index (BMI), and Fib-4 index.

AIM

To investigate whether the area of the NASH pentagon we propose is useful in discriminating between NASH and NAFL.

METHODS

This non-invasive, prospective, observational study included patients diagnosed with fatty liver by abdominal ultrasound between September 2021 and August 2022 in whom shear wave elastography, SWD, and ATI were measured. Histological diagnosis based on liver biopsy was performed in 31 patients. The large pentagon group (LP group) and the small pentagon group (SP group), using an area of 100 as the cutoff, were compared; the NASH diagnosis rate was also investigated. In patients with a histologically confirmed diagnosis, receiver-operating characteristic (ROC) curve analyses were performed.

RESULTS

One hundred-seven patients (61 men, 46 women; mean age 55.1 years; mean BMI 26.8 kg/m²) were assessed. The LP group was significantly older (mean age: 60.8 ± 15.2 years vs 46.4 ± 13.2 years; P < 0.0001). Twenty-five patients who underwent liver biopsies were diagnosed with NASH, and 6 were diagnosed with NAFL. On ROC curve analyses, the areas under the ROC curves for SWS, dispersion slope, ATI value, BMI, Fib-4 index, and the area of the NASH pentagon were 0.88000, 0.82000, 0.58730, 0.63000, 0.59333, and 0.93651, respectively; the largest was that for the area of the NASH pentagon.

CONCLUSION

The NASH pentagon area appears useful for discriminating between patients with NASH and those with NAFL.

Role of Multiparametric Ultrasound in Evaluating Hepatic Acute Graft-versus-Host Disease: An Animal Study

OBJECTIVE

Hepatic acute graft-versus-host disease (aGVHD) is a serious complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT) and is one of the leading causes of early non-recurrent death. The current diagnosis is based mainly based on clinical diagnosis, and there is a lack of non-invasive quantitative diagnosis methods. We propose a multiparametric ultrasound (MPUS) imaging method and explore its effectiveness in evaluating hepatic aGVHD.

METHODS

In this study, 48 female Wistar rats were used as receptors and 12 male Fischer 344 rats were used as donors for allo-HSCT to establish aGVHD models. After transplantation, 8 rats were randomly selected for ultrasonic examination weekly, including color Doppler ultrasound, contrast-enhanced ultrasound (CEUS) and shear wave dispersion (SWD) imaging. The values of nine ultrasonic parameters were obtained. Hepatic aGVHD was subsequently diagnosed by histopathological analysis. A classification model for predicting hepatic aGVHD was established using principal component analysis and support vector machines.

RESULTS

According to the pathological results, the transplanted rats were categorized into the hepatic aGVHD and non-GVHD (nGVHD) groups. All parameters obtained by MPUS differed statistically between the two groups. The first three contributing percentages of principal component analysis results were resistivity index, peak intensity and shear wave dispersion slope, respectively. The accuracy of classifying aGVHD and nGVHD using support vector machines reached 100%. The accuracy of the multiparameter classifier was significantly higher than that of the single parameter.

CONCLUSION

The MPUS imaging method has proven to be useful in detecting hepatic aGVHD.

The role of shear viscosity as a biomarker for improving chronic kidney disease detection using shear wave elastography: A computational study using a validated finite element model

The application of ultrasound shear wave elastography for detecting chronic kidney disease, namely renal fibrosis, has been widely studied. A good correlation between tissue Young's modulus and the degree of renal impairment has been established. However, the current limitation of this imaging modality pertains to the linear elastic assumption used in quantifying the stiffness of renal tissue in commercial shear wave elastography systems. As such, when underlying medical conditions such as acquired cystic kidney disease, which may potentially influence the viscous component of renal tissue, is present concurrently with renal fibrosis, the accuracy of the imaging modality in detecting chronic kidney disease may be affected. The findings in this study demonstrate that quantifying the stiffness of linear viscoelastic tissue using an approach similar to those implemented in commercial shear wave elastography systems led to percentage errors as high as 87%. The findings presented indicate that use of shear viscosity to detect changes in renal impairment led to a reduction in percentage error to values as low as 0.3%. For cases in which renal tissue was affected by multiple medical conditions, shear viscosity was found to be a good indicator in gauging the reliability of the Young's modulus (quantified through a shear wave dispersion analysis) in detecting chronic kidney disease. The findings show that percentage error in stiffness quantification can be reduced to as low as 0.6%. The present study demonstrates the potential use of renal shear viscosity as a biomarker to improve the detection of chronic kidney disease.

Liver Function in Patients with Long-Term Coronavirus Disease 2019 of up to 20 Months: A Cross-Sectional Study

The long-term laboratory aspects of the effects of coronavirus disease 2019 (COVID-19) on liver function are still not well understood. Therefore, this study aimed to evaluate the hepatic clinical laboratory profile of patients with up to 20 months of long-term COVID-19. A total of 243 patients of both sexes aged 18 years or older admitted during the acute phase of COVID-19 were included in this study. Liver function analysis was performed. Changes were identified in the mean levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), and ferritin. A ferritin level of >300 U/L was observed in the group that presented more changes in liver function markers (ALT, AST, and GGT). Age ≥ 60 years, male sex, AST level > 25 U/L, and GGT level ≥ 50 or 32 U/L were associated with an ALT level > 29 U/L. A correlation was found between ALT and AST, LDH, GGT, and ferritin. Our findings suggest that ALT and AST levels may be elevated in patients with long-term COVID-19, especially in those hospitalised during the acute phase. In addition, an ALT level > 29 U/L was associated with changes in the levels of other markers of liver injury, such as LDH, GGT, and ferritin.

Prognostic significance of spleen shear wave elastography and dispersion in patients with heart failure: the crucial role of cardio-splenic axis

INTRODUCTION

The interaction between the heart and spleen plays a crucial role among cardiac and multiple organ networks, particularly in heart failure (HF). Ultrasound shear wave imaging is a non-invasive technology capable of quantifying tissue quality, but its significance in the spleen in patients with HF is poorly understood.

METHODS AND RESULTS

This prospective observational study enrolled hospitalized 232 patients with HF undergoing abdominal ultrasonography. We used shear wave elastography (SWE) to assess spleen tissue elasticity and shear wave dispersion (SWD) to assess spleen tissue viscosity. Clinical, echocardiography, right heart catheterization, and outcome data were collected. Spleen SWE was negatively correlated with right ventricular fractional area change (R =  - 0.180, P = 0.039), but not with right-sided pressure or congestion indices. When patients were divided into three groups based on tertile values of splenic parameters, Kaplan-Meier analysis demonstrated that patients with the highest spleen SWE and SWD had lower event-free survival rates from cardiac deaths and decompensated HF over a median 494-days follow-up period (P < 0.0001 and P < 0.0001, respectively). In a multivariable Cox proportional hazard model, both spleen SWE and SWD were independently associated with increased risks of adverse cardiac events (hazard ratio, 4.974 and 1.384; P = 0.003 and P < 0.0001). Mechanistically, we evaluated mRNA expressions of CD36, a monocyte/macrophage-associated molecule, in peripheral leukocytes, and found that enhanced spleen stiffness was associated with the upregulation of CD36 expressions.

CONCLUSION

Share wave imaging of the spleen is useful for stratifying the prognosis of HF patients and may suggest a role of the cardio-splenic axis in HF pathogenies.

Different Ultrasound Shear Wave Elastography Techniques as Novel Imaging-Based Approaches for Quantitative Evaluation of Hepatic Steatosis-Preliminary Findings

BACKGROUND

Modern ultrasound (US) shear-wave dispersion (SWD) and attenuation imaging (ATI) can be used to quantify changes in the viscosity and signal attenuation of the liver parenchyma, which are altered in hepatic steatosis. We aimed to evaluate modern shear-wave elastography (SWE), SWD and ATI for the assessment of hepatic steatosis.

METHODS

We retrospectively analyzed the US data of 15 patients who underwent liver USs and MRIs for the evaluation of parenchymal disease/liver lesions. The USs were performed using a multifrequency convex probe (1-8 MHz). The quantitative US measurements for the SWE (m/s/kPa), the SWD (kPa-m/s/kHz) and the ATI (dB/cm/MHz) were acquired after the mean value of five regions of interest (ROIs) was calculated. The liver MRI (3T) quantification of hepatic steatosis was performed by acquiring proton density fat fraction (PDFF) mapping sequences and placing five ROIs in artifact-free areas of the PDFF scan, measuring the fat-signal fraction. We correlated the SWE, SWD and ATI measurements to the PDFF results.

RESULTS

Three patients showed mild steatosis, one showed moderate steatosis and eleven showed no steatosis in the PDFF sequences. The calculated SWE cut-off (2.5 m/s, 20.4 kPa) value identified 3/4 of patients correctly (AUC = 0.73, p > 0.05). The SWD cut-off of 18.5 m/s/kHz, which had a significant correlation (r = 0.55, p = 0.034) with the PDFF results (AUC = 0.73), identified four patients correctly (p < 0.001). The ideal ATI (AUC = 0.53 (p < 0.05)) cut-off was 0.59 dB/cm/MHz, which showed a significantly good correlation with the PDFF results (p = 0.024).

CONCLUSION

Hepatic steatosis can be accurately detected using all the US-elastography techniques applied in this study, although the SWD and the SWE showed to be more sensitive than the PDFF.

Diagnostic efficiency on ultrasound shear wave elastography in evaluation of steatosis severity for non-alcoholic fatty liver disease: a rat model

BACKGROUND

The pathological feature of steatosis affects the elasticity values measured by shear wave elastography (SWE) is still controversial in non-alcoholic fatty liver disease (NAFLD). The aim of this study is to demonstrate the influence of steatosis on liver stiffness measured by SWE on a rat model with NAFLD and analyze feasibility of SWE for grading steatosis in absence of fibrosis.

METHODS

Sixty-six rats were fed with methionine choline deficient diet or standard diet to produce various stages of steatosis; 48 rats were available for final analysis. Rats underwent abdominal ultrasound SWE examination and pathological assessment. Liver histopathology was analyzed to assess the degree of steatosis, inflammation, ballooning, and fibrosis according to the non-alcoholic fatty liver disease activity score. The diagnostic performance of SWE for differentiating steatosis stages was estimated according to the receiver operating characteristic (ROC) curve. Decision curve analysis (DCA) was conducted to determine clinical usefulness and the areas under DCA (AUDCAs) calculated.

RESULTS

In multivariate analysis, steatosis was an independent factor affecting the mean elastic modules (B = 1.558, P < 0.001), but not inflammation (B =  - 0.031, P = 0.920) and ballooning (B = 0.216, P = 0.458). After adjusting for inflammation and ballooning, the AUROC of the mean elasticity for identifying S ≥ S1 was 0.956 (95%CI: 0.872-0.998) and the AUDCA, 0.621. The AUROC for distinguishing S ≥ S2 and S = S3 was 0.987 (95%CI: 0.951-1.000) and 0.920 (95%CI: 0.816-0.986) and the AUDCA was 0.506 and 0.256, respectively.

CONCLUSIONS

Steatosis is associated with liver stiffness and SWE may have the feasibility to be introduced as an assistive technology in grading steatosis for patients with NAFLD in absence of fibrosis.

Relationship between Novel Elastography Techniques and Renal Fibrosis-Preliminary Experience in Patients with Chronic Glomerulonephritis

INTRODUCTION

A renal biopsy represents the gold standard in the diagnosis, prognosis, and management of patients with glomerulonephritis. So far, non-invasive elastographic techniques have not confirmed their utility in replacing a biopsy; however, the new and improved software from Hologic Supersonic Mach 30 is a promising method for assessing the renal tissue's stiffness and viscosity. We investigated whether this elastography technique could reveal renal tissue fibrosis in patients with chronic glomerulonephritis.

MATERIALS AND METHODS

Two-dimensional-shear wave elastography (SWE) PLUS and viscosity plane-wave ultrasound (Vi PLUS) assessments were performed in 40 patients with chronic glomerulopathies before being referred for a renal biopsy. For each kidney, the mean values of five stiffness and viscosity measures were compared with the demographic, biological, and histopathological parameters of the patients.

RESULTS

In total, 26 men and 14 women with a mean age of 52.35 ± 15.54 years, a mean estimated glomerular filtration rate (eGFR) of 53.8 ± 35.49 mL/min/1.73m2, and a mean proteinuria of 6.39 ± 7.42 g/24 h were included after providing their informed consent. Out of 40 kidney biopsies, 2 were uninterpretable with inappropriate material and were divided into four subgroups based on their fibrosis percentage. Even though these elastography techniques were unable to differentiate between separate fibrosis stages, when predicting between the fibrosis and no-fibrosis group, we found a cut-off value of <20.77 kPa with the area under the curve (AUC) of 0.860, a p < 0.001 with 88.89% sensitivity, and a 75% specificity for the 2D SWE PLUS measures and a cut-off value of <2.8 Pa.s with an AUC of 0.792, a p < 0.001 with 94% sensitivity, and a 60% specificity for the Vi PLUS measures. We also found a cut-off value of <19.75 kPa for the 2D SWE PLUS measures (with an AUC of 0.789, p = 0.0001 with 100% sensitivity, and a 74.29% specificity) and a cut-off value of <1.28 Pa.s for the Vi PLUS measures (with an AUC 0.829, p = 0.0019 with 60% sensitivity, and a 94.29% specificity) differentiating between patients with over 40% fibrosis and those with under 40%. We also discovered a positive correlation between the glomerular filtration rate (eGFR) and 2D-SWE PLUS values (r = 0.7065, p < 0.0001) and Vi PLUS values (r = 0.3637, p < 0.0211). C reactive protein (CRP) correlates with the Vi PLUS measures (r = -0.3695, p = 0.0189) but not with the 2D SWE PLUS measures (r = -0.2431, p = 0.1306).

CONCLUSION

Our findings indicate that this novel elastography method can distinguish between individuals with different stages of renal fibrosis, correlate with the renal function and inflammation, and are easy to use and reproducible, but further research is needed for them to be employed routinely in clinical practice.

Stratifying Non-alcoholic Steatohepatitis With the Non-invasive Ultrasound Markers Shear Wave Dispersion Slope and Shear Wave Velocity: An Animal Study

We evaluated the significance of the ultrasound (US) markers shear wave dispersion slope (SWDS) and shear wave velocity (SWV) for identification of non-alcoholic steatohepatitis (NASH) and high-risk NASH; the latter was defined as the presence of steatohepatitis, a non-alcoholic fatty liver disease activity score (NAS) ≥4 or a fibrosis stage ≥2. Thirty-six male Sprague-Dawley (SD) rats were assigned to two groups: the study (n = 30) and control (n = 6) groups. To initiate non-alcoholic steatohepatitis, study group rats were fed a diet deficient in methionine and choline. All rats were examined using ultrasonography to obtain the SWDS and SWV parameters of the liver at the same time points. Fatty liver pathological grades were determined after euthanasia; the livers were categorized in the normal (n = 6), NAFL (non-alcoholic fatty liver) (n = 10) and NASH (n = 20) subgroups based on the NAS scoring system. They were also categorized into subgroups F0 (n = 22), F1 (n = 3), F2 (n = 7) and F3 (n = 4) on the basis of the METAVIR (Meta-analysis of Histological Data in Viral Hepatitis) scoring system. Measurement differences between various grades were evaluated by analysis of variance (ANOVA) or the Mann-Whitney U-test. We used logistic regression to calculate a combination of the two parameters for combined assessment of parameters. The diagnostic value of SWDS, SWV and the two-variable model was determined by receiver operating characteristic (ROC) curve analysis. This analysis revealed stepwise increases in SWDS and SWV with increasing NAFLD severity. The accuracy of SWDS in diagnosing NASH was good (area under the ROC curve [AUC]: 0.88) and was superior to that of SWV (AUC: 0.76). The combination of SWV and SWDS exhibited higher performance (AUC: 0.90). SWV was higher than SWDS in participants with a fibrosis grade ≥2 (high-risk NASH). For identification of high-risk NASH, SWV exhibited the best diagnostic performance (AUC: 0.89), which was equivalent to that of the two-variable model (AUC: 0.88) and slightly higher than that of SWDS (AUC: 0.85). This study indicates that of the US-based markers, SWDS outperforms SWV in identifying NASH in rats and that combining the two markers may increase their clinical utility in guiding NAFLD and NASH treatment.

Shear Wave Dispersion Slope Measured with Shear Wave Dispersion Imaging Is Associated with Variceal Hemorrhage in Cirrhotic Patients

Background and Objectives: Portal hypertension (PH), as the main consequence of cirrhosis, leads to the development of gastroesophageal varices (GEVs). Variceal hemorrhage (VH) caused by the rupture of GEVs is a life-threatening emergency. Thus, the prediction of VH risk is considerably important. Our pilot study aimed to identify the risk factors of variceal hemorrhage (VH) in cirrhosis. Materials and Methods: Cirrhotic patients were prospectively included and divided into two groups according to the presence or absence of VH. Conventional ultrasound and shear wave dispersion (SWD) imaging were conducted to detect the portal vein diameter, spleen diameter, ascites, liver stiffness (LS) and shear wave dispersion slope (SWDS). The laboratory tests were recorded, including platelets (PLT), alanine transaminase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL) and albumin (ALB). The risk factors of VH were screened using univariate analyses and identified using multivariate logistic regression. The ROC curves were used to assess diagnostic accuracy. Comparisons between AUCs were performed using the Delong method. Results: Sixty-five patients with 22 VHs were finally included. The SWDS, spleen diameter and ascites were identified as independent risk factors for VH. The SWDS showed good performance for diagnosing VH (AUC = 0.768, 95% CI: 0.647−0.864), and sensitively identified 95.5% (95% CI: 77.2%−99.9%) of patients with VH. Including the three risk factors in multivariate logistic regression, we obtained a formula for diagnosing VH: −20.749 + 0.804 × SWDS + 0.449 × spleen diameter + 1.803 × ascites (no ascites = 0, ascites = 1). Comparison of AUCs revealed that the formula (AUC = 0.900, 95% CI: 0.800−0.961) performed better than LS, SWDS, and spleen diameter in diagnosing VH (p < 0.001; p < 0.05; p < 0.05). Conclusions: SWDS is a sensitive parameter for assessing the risk of VH. Combining the SWDS, spleen diameter and ascites resulted in good diagnostic accuracy.

Non-Invasive Evaluation of Kidney Elasticity and Viscosity in a Healthy Cohort

Introduction: There is currently a lack of published data on kidney elasticity and viscosity. Non-invasive techniques, such as two-dimensional shear-wave elastography (2D-SWE PLUS) and viscosity plane-wave ultrasound (Vi PLUS), have surfaced as new detection methods, which, thanks to efficient processing software, are expected to improve renal stiffness and viscosity measurements. This study aims to be the first one to assess the normal range values in normal renal function subjects and to investigate the factors that impact them. Methods: We conducted a cross-sectional study employing 50 participants (29 women and 21 men) with a mean age of 42.22 ± 13.17, a mean estimated glomerular filtration rate (eGFR) of 97.12 ± 11 mL/min/1.73 m2, a mean kidney length of 10.16 ± 0.66 cm, and a mean body mass index (BMI) of 24.24 ± 3.98. With a C6-1X convex transducer and the Ultra-FastTM software available on the Hologic Aixplorer Mach 30 ultrasound system, we acquired five measurements of renal cortical stiffness and viscosity (achieved from five distinct images in the middle part of the subcapsular cortex) from each kidney. The ten measurements’ median values correlated with the participant’s demographical, biological, and clinical parameters. Results: The mean kidney elasticity was 31.88 ± 2.89 kiloPascal (kPa), and the mean viscosity was 2.44 ± 0.57 Pascal.second (Pa.s) for a mean measurement depth 4.58 ± 1.02 cm. Renal stiffness seemed to be influenced by age (r = −0.7047, p < 0.0001), the measurement depth (r = −0.3776, p = 0.0075), and eGFR (r = 0.6101, p < 0.0001) but not by BMI (r = −0.2150, p = 0.1338), while viscosity appeared to be impacted by age (r = −0.4251, p = 0.0021), eGFR (r = 0.4057, p = 0.0038), the measurement depth (r = −0.4642, p = 0.0008), and BMI (r = −0.3676, p = 0.0086). The results of the one-way ANOVA used to test the differences in the variables among the three age sub-groups are statistically significant for both 2D-SWE PLUS (p < 0.001) and Vi PLUS (p = 0.015). The method found good intra-operator reproducibility for the 2D-SWE PLUS measurements, with an ICC of 0.8365 and a 95% CI of 0.7512 to 0.8990, and for the Vi PLUS measurements, with an ICC of 0.9 and a 95% CI of 0.8515 to 0.9397. Conclusions: Renal stiffness and viscosity screening may become an efficacious, low-cost way to gather supplemental diagnostic data from patients with chronic kidney disease (CKD). The findings demonstrate that these non-invasive methods are highly feasible and not influenced by gender and that their values correlate with renal function and decrease with age progression. Nevertheless, more research is required to ascertain their place in clinical practice.

Predicting Progression of Kidney Injury Based on Elastography Ultrasound and Radiomics Signatures

Background: Shear wave elastography ultrasound (SWE) is an emerging non-invasive candidate for assessing kidney stiffness. However, its prognostic value regarding kidney injury is unclear. Methods: A prospective cohort was created from kidney biopsy patients in our hospital from May 2019 to June 2020. The primary outcome was the initiation of renal replacement therapy or death, while the secondary outcome was eGFR < 60 mL/min/1.73 m2. Ultrasound, biochemical, and biopsy examinations were performed on the same day. Radiomics signatures were extracted from the SWE images. Results: In total, 187 patients were included and followed up for 24.57 ± 5.52 months. The median SWE value of the left kidney cortex (L_C_median) is an independent risk factor for kidney prognosis for stage 3 or over (HR 0.890 (0.796−0.994), p < 0.05). The inclusion of 9 out of 2511 extracted radiomics signatures improved the prognostic performance of the Cox regression models containing the SWE and the traditional index (chi-square test, p < 0.001). The traditional Cox regression model had a c-index of 0.9051 (0.8460−0.9196), which was no worse than the machine learning models, Support Vector Machine (SVM), SurvivalTree, Random survival forest (RSF), Coxboost, and Deepsurv. Conclusions: SWE can predict kidney injury progression with an improved performance by radiomics and Cox regression modeling.

Efficacy of shear wave dispersion imaging for viscoelastic assessment of the liver in acute graft-versus-host disease rats

BACKGROUND

To investigate the feasibility of using shear wave dispersion (SWD) imaging to evaluate hepatic acute graft-versus-host disease (aGVHD) in a rat model.

METHODS

To establish an aGVHD model, 30 Wistar rats were subjected to bone marrow transplantation, 10 Fischer 344 rats were used as donors, and 6 Wistar rats were used as the control group. Each week, 6 rats were randomly chosen and divided into groups of 1 week (1 w) to 5 weeks (5 w). For each subgroup, the rats received a clinical index assessment and shear wave dispersion (SWD) examination with 2 quantitative values, shear wave (SW) speed and SWD slope. The histological characteristics were then used as the reference standard to divide the rats into the aGVHD group and the no aGVHD (nGVHD) group.

RESULTS

In the 2 weeks (2 w) group, only SWD slope [median: 7.26, interquartile range (IQR): 7.04 to 7.31] showed a significant increase in the measured value (P<0.05). The value of the 3 weeks (3 w) group (median: 7.88, IQR: 7.84 to 8.49) significantly increased compared with the 2 w value (P<0.05). Although the value increased gradually from week 3 to week 5, it had no statistical significance (P>0.05). The SW speed [mean ± standard deviation (SD): 1.54±0.11, 95% confidence interval (CI): 1.48 to 1.59] and SWD slope (mean ± SD: 8.29±0.56, 95% CI: 7.99 to 8.59) of the aGVHD group were higher than those of the control group and the nGVHD group (P<0.001). The correlation of SWD slope with pathological grade was the highest (r=0.798, P<0.01), followed by SW speed (r=0.785, P<0.01), and the correlation of clinical index with pathological grade was the lowest (r=0.751, P<0.01). In addition, the area under the receiver operating characteristic (ROC) curve (AUC) value of aGVHD using the SWD slope was 0.844 (95% CI: 0.67 to 0.95, sensitivity: 93.75%, specificity: 78.57%), which was higher than the AUC of both SW speed and clinical index, and the difference was statistically significant compared to the AUC of the clinical index.

CONCLUSIONS

The SWD slope could show significant abnormalities earlier than SW speed and clinical index and is also more consistent with the change in aGVHD severity level. The SWD slope may help in detecting hepatic aGVHD during ultrasound SWD examination.

Viscosity Plane-Wave UltraSound (Vi PLUS) in the Evaluation of Thyroid Gland in Healthy Volunteers-A Preliminary Study

Viscosity and elasticity represent biomechanical properties of soft tissues that suffer changes during the pathophysiological alterations of the tissue in various conditions. This study aimed to determine average viscosity values for the thyroid gland and to evaluate the potential influences of age, gender and body mass index (BMI), using a recent technique Viscosity Plane-wave UltraSound (Vi PLUS). A total of 85 healthy Caucasian volunteers (56 women and 29 men, median age of 29 years, range 17−81 years) were included in this prospective monocentric study conducted between January 2022 and March 2022. Thyroid viscosity was measured using the SuperSonic MACH 30® Ultrasound system (Aixplorer, SuperSonic Imagine, Aix-en-Provence, France), equipped with a curvilinear C6-IX transducer that allows simultaneous quantification of the viscosity and stiffness. The mean thyroid viscosity measurement value was 2.63 ± 0.47 Pa.s. No statistically significant differences were detected between the left and the right lobes of the thyroid gland. A significant positive correlation was found between thyroid viscosity and elasticity (r = 0.685, p < 0.0001). There was no statistically significant correlation between body mass index (BMI) and thyroid gland viscosity and elasticity values (r = 0.215, p = 0.053; r = 0.106, p = 0.333). No correlation between viscosity and gender was established (p > 0.05). Vi PLUS represents a new and promising ultrasonographic technique that can provide helpful information for evaluating the thyroid parenchyma, similar to elastography. The effect of the potential confounding factors on thyroid viscosity was negligible, except for BMI.

Shear Wave Dispersion Imaging for the Characterization of Focal Liver Lesions - A Pilot study

PURPOSE

Shear wave dispersion imaging is a novel ultrasound-based technique, which analyzes the speed of different shear wave components depending on their frequency. The dispersion of shear wave speed correlates with the viscosity of the liver parenchyma. The aim of this prospective study was to evaluate the use of shear wave dispersion imaging in focal liver lesions in the non-cirrhotic liver.

METHODS

Patients with unclear focal liver lesions in B-mode ultrasound were prospectively assigned to shear wave dispersion imaging (m/s/kHz). Measurements were conducted within the lesion and in the liver parenchyma of the right liver lobe using an intercostal window. Histology and contrast-enhanced ultrasound served as the reference for the characterization of the lesions.

RESULTS

Out of 46 patients included in this study, 24 had liver metastases and 22 had benign liver lesions. Benign lesions consisted mostly of hemangiomas (n=12) and focal nodular hyperplasia (n=8). Malignant lesions showed significantly lower shear wave dispersion (13.0±2.45 m/s/kHz) compared to benign tumors (15.2±2.74 m/s/kHz, p<0.01). In further subgroup analysis, the difference was significant for hemangiomas (15.32±2.42 m/s/kHz, p=0.04) but not for FNHs (14.98±3.36 m/s/kHz, p=0.38). The dispersion of reference liver parenchyma did not differ significantly between the groups (p=0.54).

CONCLUSION

The quantification of viscosity by shear wave dispersion is a new parameter for the characterization of focal liver lesions with higher dispersion values in hemangiomas and lower dispersion values in metastases. However, it cannot differentiate reliably between benign and malignant lesions.

Viscoelasticity assessment for in vivo quantification of muscle contusion injury in rats using shear wave elastography

The aim of the study described here was to investigate the role of viscoelasticity in assessing muscle fibrosis and inflammation in a rat model of contusion using quantitative shear wave elastography (SWE). Unilateral gastrocnemius muscle contusion was induced in 32 male rats using an impactor apparatus. The contralateral muscles served as the control group. SWE was applied to the control group and rats 1, 3, 14 and 21 d after successful modeling (each time point group, n = 8). Histologic features were used as reference standards. The degree of fibrosis was moderately correlated with shear wave speed (r = 0.53), whereas the degree of inflammation was well correlated with shear wave dispersion (SWD) slope (r = 0.74). The area under the receiver operating characteristic curve (AUC) for the dispersion slope for muscle inflammation and fibrosis assessment was 0.87 (95% confidence interval: 0.705-0.963), which exceeded that of the shear wave speed (0.68, 95% confidence interval: 0.494-0.834). The larger decline in dispersion slope in the fibrotic stage than in the inflammation stage (1-d group vs. 14-d group or 21-d group, p < 0.05) indicated better predictive performance than the shear wave speed.

Shear-Wave Elastography and Viscosity PLUS for the Assessment of Peripheric Muscles in Healthy Subjects: A Pre- and Post-Contraction Study

Viscosity is a novel parameter, recently introduced in the use of elastographic techniques, correlating to shear-wave dispersion. The purpose of this study was to provide normal reference viscosity values for the peripheral muscles in healthy volunteers. This prospective study included 38 subjects who underwent US examinations between November 2021 and January 2022. Measurements were taken on the calf and the deltoid muscles in both pre- and post-contraction states. The age range was 21–29 years, with a median of 26 years. The SWE and ViPLUS values in the deltoid muscles were significantly higher than in the soleus muscles in both pre- and post-contraction sets (p = 0.002). There were statistically significant differences between the pre- and post-contraction values for both the SWE and ViPLUS values in the subgroup analysis. The ICC estimates and the 95% confidence intervals were based on a mean rating (k = 2), an absolute agreement, and a two-way random-effects model, demonstrating excellent agreement between the measurements taken by the two examiners.

Functional Evaluation of Major Salivary Glands Using Viscosity PLUS and 2D Shear-Wave PLUS Elastography Techniques in Healthy Subjects-A Pilot Study

Biological soft tissues are characterized by viscoelastic properties. The propagation of shear waves within tissues is influenced by both elasticity, which is linked to the shear wave speed, and viscosity, which is linked to the shear wave dispersion. This study aimed to functionally assess the parotid glands (PG) and submandibular glands (SMG) in a group of 40 healthy subjects using the novel Viscosity PLUS (Vi.PLUS) and 2D Shear-Wave Elastography PLUS (2D-SWE.PLUS) techniques. The viscosity and stiffness of PG and SMG were measured before and after gustatory stimulation with a sialagogue agent (commercially available lemon juice) using the new SuperSonic MACH 30 ultrasound system equipped with a curvilinear C6-1X transducer. PG presented a mean basal viscosity and elasticity of 2.10 ± 0.19 Pa.s and 11.32 ± 1.91 kPa, respectively, which significantly increased poststimulation to 2.39 ± 0.17 Pa.s (p < 0.001) and 12.58 ± 1.92 kPa (p < 0.001), respectively. SMG did not present statistically increased values of viscosity and elasticity following stimulation (2.31 ± 015 Pa.s vs. 2.37 ± 0.18 Pa.s, p = 0.086, and 10.40 ± 1.64 kPa vs. 10.90 ± 1.98 kPa, p = 0.074, respectively). Vi.PLUS measurements presented a good positive correlation with 2D-SWE.PLUS values for PG and SMG, before and after stimulation. Gender and BMI were not confounding factors for these two parameters. Vi.PLUS represents an innovative non-invasive imaging technique that, together with 2D-SWE.PLUS proves to be useful in functionally assessing the major salivary glands in healthy subjects.

US Shear-Wave Elastography Dispersion for Characterization of Chronic Liver Disease

Background Little is known about the benefits of the use of dispersion slope (DS) as a viscosity-related parameter derived from two-dimensional (2D) shear-wave elastography (SWE) in the stratification of hepatic pathologic stages. Purpose To evaluate whether DS as an additional parameter can improve the diagnostic performance in detecting liver necroinflammation, fibrosis, and steatosis. Materials and Methods In this prospective study, consecutive participants with chronic liver disease who underwent liver biopsy and 2D SWE were recruited between July 2019 and September 2020. DS and liver stiffness (LS) measurements were obtained with use of a 2D SWE system immediately before biopsy. The biopsy specimens were assessed to obtain the scores of fibrosis, necroinflammation, and steatosis. Differences in the area under the receiver operating characteristic curve (AUC) were used to compare the diagnostic performance of DS, LS, and a combination of DS and LS. Results There were 159 participants evaluated (among them, 79 participants with chronic hepatitis B and 11 participants with nonalcoholic fatty liver disease). The distributions of DS values among various necroinflammatory activities (P = .02) and fibrosis stages (P < .001) were different. Moreover, DS was only associated with fibrosis after subgroup analysis based on the fibrosis stages and necroinflammatory activities (P < .001). The AUCs of DS in detecting clinically significant fibrosis (fibrosis stage ≥F2), cirrhosis (fibrosis stage of F4), and moderate to severe necroinflammatory activity (necroinflammatory activity ≥A2) were 0.72 (95% CI: 0.64, 0.79), 0.71 (95% CI: 0.63, 0.78), and 0.64 (95% CI: 0.55, 0.71), respectively. The differences of AUCs were not apparent for the DS and LS combination model after excluding DS (fibrosis stage ≥F2: 0.00 [95% CI: 0.00, 0.01], fibrosis stage of F4: -0.01 [95% CI: -0.02, 0.00], and necroinflammatory activity ≥A2: 0.00 [95% CI: 0.00, 0.01]). Conclusion The addition of dispersion slope derived from two-dimensional shear-wave elastography did not improve the diagnostic performance in detecting liver fibrosis, necroinflammation, or steatosis in patients with primarily viral hepatitis. ClinicalTrials.gov registration no.: NCT03777293 © RSNA, 2022 Online supplemental material is available for this article.

Assessment of Renal Allograft Stiffness and Viscosity Using 2D SWE PLUS and Vi PLUS Measures-A Pilot Study

Elastography is a useful noninvasive tool for the assessment of renal transplant recipients. 2D-shear wave elastography (SWE) PLUS and viscosity plane-wave ultrasound (Vi PLUS) have emerged as novel techniques that promise to offer improved renal stiffness and viscosity measures due to improved processing algorithms. Methods: We performed a cross-sectional study of 50 kidney transplanted patients (16 women, 34 men; mean age of 47.5 ± 12.5; mean estimated glomerular filtration rate (eGFR) estimated by Chronic Kidney Disease Epidemiology Collaboration formula: 52.19 ± 22.6 mL/min/1.73 m2; and a mean duration after transplant of 10.09 ± 5 years). For every patient, we obtained five valid measurements of renal stiffness (obtained from five different frames in the cortex of the renal graft), and also tissue viscosity, with a C6-1X convex transducer using the Ultra-Fast™ software available on the Aixplorer Mach 30 ultrasound system (Supersonic Imagine, Aix-en-Provence, France). The median values of elastographic and viscosity measures have been correlated with the patients’ demographic, biological, and clinical parameters. Results: We obtained a cut-off value of renal cortical stiffness of <27.3 kiloPascal(kPa) for detection of eGFR < 60 mL/min/1.73 m2 with 80% sensitivity and 85% specificity (AUC = 0.811, p < 0.0001), a cut-off value of <26.9 kPa for detection of eGFR < 45 mL/min/1.73 m2 with 82.6% sensitivity and 74% specificity (AUC = 0.789, p < 0.0001), and a cut-off value of <23 kPa for detection of eGFR < 30 mL/min/1.73 m2 with 88.8% sensitivity and 75.6% specificity (AUC = 0.852, p < 0.0001). We found a positive correlation coefficient between eGFR and the median measure of renal cortical stiffness (r = 0.5699, p < 0.0001), between eGFR the median measure of viscosity (r = 0.3335, p = 0.0180), between median depth of measures and renal cortical stiffness (r = −0.2795, p = 0.0493), and between median depth of measures and body mass index (BMI) (r = 0.6574, p < 0.0001). Our study showed good intra-operator agreement for both 2D SWE PLUS measures—with an intraclass correlation coefficient (ICC) of 0.9548 and a 95% CI of 0.9315 to 0.9719—and Vi PLUS, with an ICC of 0.8323 and a 95% CI of 0.7457 to 0.8959. The multivariate regression model showed that 2D SWE PLUS values were associated with eGFR, Vi PLUS, and depth of measures. Conclusions: Assessment of renal allograft stiffness and viscosity may prove to be an effective method for identifying patients with chronic allograft injury and could prove to be a low-cost approach to provide additional diagnostic information of kidney transplanted patients.

Shear-Wave Elastography Using Commercially Available Ultrasound in a Mouse Model of Chronic Liver Disease

Elastography is currently used clinically to diagnose the degree of liver stiffness. We sought to develop a shear-wave elastography (SWE) measurement method using ultrasound in mice and to compare its results with those of other noninvasive tests for liver fibrosis. We divided male mice into three groups (normal (G1), liver fibrosis (G2), and fatty liver (G3)). We measured mouse liver SWE values and compared them with T1rho and T2 values from magnetic resonance imaging results. We also compared the SWE values with the expression levels of a serum liver fibrosis biomarker (Mac-2-binding protein (M2BP)) and hepatic genes. SWE values significantly increased over time in G2 but did not change in G3. T1rho values in G2 and G3 were significantly increased compared with those in G1. T2 values in G2 did not increase compared with those in group 1. T2 values in G3 significantly increased compared with those in groups 1 and 2. In G2, SWE values significantly and positively correlated with T1rho values. SWE values significantly correlated with serum M2BP levels in G2 but did not correlate with inflammatory gene expression. We could measure SWE values to assess the degree of liver fibrosis in mouse models of liver disease.

The Non-Invasive Ultrasound-Based Assessment of Liver Viscosity in a Healthy Cohort

Liver fibrosis is the most significant prognostic factor in chronic liver disease (CLD). Clinical practice guidelines recommend the use of non-invasive techniques, such as two-dimensional shear-wave elastography (2D-SWE), to assess liver stiffness as a marker of fibrosis. Several other factors influence liver stiffness in addition to liver fibrosis. It is presumed that changes due to necro-inflammation modify the propagation of shear waves (dispersion). Therefore, new imaging techniques that investigate the dispersion properties of shear waves have been developed, which can serve as an indirect method of measuring liver viscosity (Vi PLUS). Defining the reference values in healthy subjects among different age groups and genders and analyzing the factors that influence these values is essential. However, published data on liver viscosity are still limited. This is the first study that aimed to assess the normal range of liver viscosity values in subjects with healthy livers and analyze the factors that influence them. One hundred and thirty-one consecutive subjects with healthy livers were enrolled in this prospective study. The results showed that Vi PLUS is a highly feasible method. Liver stiffness, age and BMI influenced the liver viscosity values. The mean liver viscosity by Vi PLUS in subjects with healthy livers was 1.59 Pa·s.