Accuracy of real-time shear wave elastography for assessing liver fibrosis in chronic hepatitis C: a pilot study

Therapeutic and diagnostic targeting of fibrosis in metabolic, proliferative and viral disorders

Fibrosis is a common denominator in many pathologies and crucially affects disease progression, drug delivery efficiency and therapy outcome. We here summarize therapeutic and diagnostic strategies for fibrosis targeting in atherosclerosis and cardiac disease, cancer, diabetes, liver diseases and viral infections. We address various anti-fibrotic targets, ranging from cells and genes to metabolites and proteins, primarily focusing on fibrosis-promoting features that are conserved among the different diseases. We discuss how anti-fibrotic therapies have progressed over the years, and how nanomedicine formulations can potentiate anti-fibrotic treatment efficacy. From a diagnostic point of view, we discuss how medical imaging can be employed to facilitate the diagnosis, staging and treatment monitoring of fibrotic disorders. Altogether, this comprehensive overview serves as a basis for developing individualized and improved treatment strategies for patients suffering from fibrosis-associated pathologies.

Tapering of the interventricular septum can affect ultrasound shear wave elastography: An in vitro and in silico study

Shear wave elastography (SWE) has the potential to determine cardiac tissue stiffness from non-invasive shear wave speed measurements, important, e.g., for predicting heart failure. Previous studies showed that waves traveling in the interventricular septum (IVS) may display Lamb-like dispersive behaviour, introducing a thickness-frequency dependency in the wave speed. However, the IVS tapers across its length, which complicates wave speed estimation by introducing an additional variable to account for. The goal of this work is to assess the impact of tapering thickness on SWE. The investigation is performed by combining in vitro experiments with acoustic radiation force (ARF) and 2D finite element simulations, to isolate the effect of the tapering curve on ARF-induced and natural waves in the heart. The experiments show a 11% deceleration during propagation from the thick to the thin end of an IVS-mimicking tapered phantom plate. The numerical analysis shows that neglecting the thickness variation in the wavenumber-frequency domain can introduce errors of more than 30% in the estimation of the shear modulus, and that the exact tapering curve, rather than the overall thickness reduction, determines the dispersive behaviour of the wave. These results suggest that septal geometry should be accounted for when deriving cardiac stiffness with SWE.

A Robust and Fast Method for 2-D Shear Wave Speed Calculation

We developed a new method, called the tangent plane method (TPM), for more efficiently and accurately estimating 2-D shear wave speed (SWS) from any direction of wave propagation. In this technique, we estimate SWS by solving the Eikonal equation because this approach is more robust to noise. To further enhance the performance, we computed the tangent plane of the arrival time surface. To evaluate the approach, we performed simulations and also conducted phantom studies. Simulation studies showed that TPM was more robust to noise than the conventional methods such as 2-D cross correlation (CC) and the distance method. The contrast/CNR for an inclusion (69 kPa; manufacturer provided stiffness) of a phantom is 0.54/4.17, 0.54/1.82, and 0.46/1.22. SWS results [mean and standard deviation (SD)] were 4.41 ± 0.49, 4.62 ± 0.85, and 3.66 ± 0.99 m/s, respectively, while the manufacturer's reported value (mean and range) is 4.81 ± 0.49 m/s. This shows that TPM has the higher CNR and lower SD than other methods. To increase the computation speed, an iterative version of TPM (ITPM) was also developed, which calculated the time-of-flight iteratively. ITPM reduced the computation time to 3.6%, i.e., from 748 to 27 s. In vivo case analysis demonstrated the feasibility of using the conventional ultrasound scanner for the proposed 2-D SWS algorithms.

Ultrasound-Based Quantification of Fibrosis and Steatosis with a New Software Considering Transient Elastography as Reference in Patients with Chronic Liver Diseases

The goal of this study was to evaluate the performance of two new ultrasound-based techniques (ShearWave PLUS elastography [2-D-SWE PLUS], SSp PLUS Imaging [SSp PLUS]) implemented on the Aixplorer Mach 30 ultrasound system (Supersonic Imagine, Aix-en-Provence, France) for the non-invasive assessment of liver steatosis and fibrosis, using transient elastography (TE) with the controlled attenuation parameter (CAP) as reference. This monocentric cross-sectional study included 133 consecutive adult patients with chronic hepatopathies. Liver stiffness and steatosis were evaluated in the same session using the techniques mentioned above. An excellent correlation was observed between liver stiffness measurements obtained with 2-D-SWE PLUS and TE (r = 0.92, p < 0.0001). The best cutoff value of 2-D-SWE PLUS for predicting F≥2 was 6.8 kPa; for F≥3, 8.4 kPa; and for F4, 11 kPa. With respect to steatosis evaluation, a strong negative correlation between CAP and SSp PLUS values (r = -0.70, p < 0.0001) was obtained. The best SSp PLUS cutoff value for predicting steatosis was 1537 m/s.

Refraction artifact on abdominal sonogram

Ultrasonography (US) is the first-line diagnostic tool for observing the whole abdomen. Unfortunately, a wide spectrum of refraction-related artefactual images is very frequently encountered in routine US examinations. In addition, most practitioners currently perform abdominal US examinations without sufficient knowledge of refraction artifacts (RAs). This review article was designed to present many representative RA images seen in the clinical setting, with a brief explanation of the mechanism of these images, in certain cases through an analyzed and reconstructed method using computer simulation that supports clinical observations. RAs are encountered not only with B-mode US but also with Doppler US, contrast-enhanced US, and shear wave elastography. RAs change their appearance according to the situation, but they always have a significant effect on detailed interpretation of abdominal US images. Correct diagnosis of abdominal US relies on a deep understanding of each characteristic artifactual finding, which necessitates knowledge of basic US physics. When analyzing mass lesions, computer simulation analysis helps to reveal the global images of RAs around a lesion.

Diagnostic performance of 2D shear wave elastography in predicting liver fibrosis in patients with chronic hepatitis B and C: a histopathological correlation study

PURPOSE

In this study, we investigated the diagnostic efficacy of 2D-Shear Wave Elastography (2D-SWE) in detecting stages of liver fibrosis and determining the disease-specific cut-off values in patients with chronic hepatitis B and C infection, using histopathological analysis as the reference method.

METHOD

Our study included 103 consecutive adult patients with chronic hepatitis B and C infection (CHB and CHC) who had liver biopsy within three months of elastography examination. A real-time 2D-SWE was performed using the LOGIQ E9 system (GE Medical Systems, Wisconsin, USA). The correlation between the liver stiffness measurements and the METAVIR scores was evaluated. The diagnostic performance of 2D-SWE was assessed, and cut-off values were set.

RESULTS

We found a statistically significant positive correlation between elastography values and the degree of liver fibrosis (Spearman's correlation coefficient = 0.76 and 0.83 for CHB and CHC; respectively) (p = 0.0001). The stiffness cut-off values were F ≥ 1: 5.92 kPa, F ≥ 2: 7.69 kPa, F ≥ 3: 8.97 kPa, F ≥ 4: 12.15 kPa in CHB; and F ≥ 1: 6.09 kPa, F ≥ 2: 7.81 kPa, F ≥ 3: 9.0 kPa, F ≥ 4: 12.47 kPa in CHC patients.

CONCLUSION

2D-SWE is reliable and accurate for the diagnosis of liver fibrosis. In selected patients, 2D-SWE may be useful in reducing the need for liver biopsy when staging fibrosis. Further studies in larger prospective series are needed to confirm these results and determine the most appropriate cut-off values for each stage of liver fibrosis.

Viscoelasticity Imaging of Biological Tissues and Single Cells Using Shear Wave Propagation

Changes in biomechanical properties of biological soft tissues are often associated with physiological dysfunctions. Since biological soft tissues are hydrated, viscoelasticity is likely suitable to represent its solid-like behavior using elasticity and fluid-like behavior using viscosity. Shear wave elastography is a non-invasive imaging technology invented for clinical applications that has shown promise to characterize various tissue viscoelasticity. It is based on measuring and analyzing velocities and attenuations of propagated shear waves. In this review, principles and technical developments of shear wave elastography for viscoelasticity characterization from organ to cellular levels are presented, and different imaging modalities used to track shear wave propagation are described. At a macroscopic scale, techniques for inducing shear waves using an external mechanical vibration, an acoustic radiation pressure or a Lorentz force are reviewed along with imaging approaches proposed to track shear wave propagation, namely ultrasound, magnetic resonance, optical, and photoacoustic means. Then, approaches for theoretical modeling and tracking of shear waves are detailed. Following it, some examples of applications to characterize the viscoelasticity of various organs are given. At a microscopic scale, a novel cellular shear wave elastography method using an external vibration and optical microscopy is illustrated. Finally, current limitations and future directions in shear wave elastography are presented.

Factors Influencing Renal Parenchymal Stiffiness in Patients with Diabetic Nephropathy

Objective

Glomerulosclerosis and tubulointerstitial fibrosis are associated with lower renal parenchymal resilience. The purpose of this study is to determine the factors influencing renal resilience in patients with diabetic nephropathy (DN).

Methods

We recruited 56 healthy volunteers and 187 patients with DN. All the participants were evaluated using shear-wave elastography (SWE), and the size of their kidneys and Young's modulus values for the parenchyma were recorded. A total of 187 patients with DN are allocated to three groups according to their urinary albumin-to-creatinine ratio: normoalbuminuric (<30 mg/g creatinine), microalbuminuric (30-300 mg/g), and macroalbuminuric (≥300 mg/g) groups. Renal resilience is compared between the stages of diabetic nephropathy and the healthy control group, and the factors affecting the stiffiness of the renal parenchyma in DN are analyzed.

Results

The renal parenchyma is harder in participants with DN than in healthy participants (P < 0.001), and the stiffiness increases with the progression of the disease (P < 0.001). Multivariate logistic regression analysis shows that disease stage (β = 0.789, P < 0.001), duration of diabetes (β = 0.028, P < 0.001), and serum creatinine (SCr) concentration (β = 0.001, p < 0.001) influence the stiffiness of the renal parenchyma.

Conclusion

We show that SWE can be used to measure changes in the stiffiness of the renal parenchyma in patients with DN. Furthermore, Young's modulus of the renal parenchyma is related to the duration of diabetes, urinary albumin excretion, and SCr concentration. Thus, SWE can be used to objectively and non-invasively stage DN.

Correlation between Liver Stiffness by Two-Dimensional Shear Wave Elastography and Waist Circumference in Japanese Local Citizens with Abdominal Obesity

Background: Various factors other than fibrosis could affect liver stiffness (LS), measured by two-dimensional shear wave elastography (2D-SWE). We aimed to clarify the factors affecting LS in local citizens. Methods: We performed a cross-sectional study among local citizens of a health checkup program. Abdominal obesity was defined as waist circumference ≥85 cm for men and ≥90 cm for women. We evaluated the correlation between LS by 2D-SWE (Aplio 500) and waist circumference with linear regression analyses. We selected the following items as variables in the multivariate analysis: waist circumference, sex, hypertension, diabetes, diagnostic components of metabolic syndrome, γ−glutamyl transpeptidase, total bilirubin, NAFLD fibrosis score, and an indicator of a fatty liver, evaluated ultrasonographically. Results: Overall, 345 individuals were included; 318 (181 men and 137 women; age, 63.4 years; waist circumference, 84.0 cm; LS, 5.79 kPa) were analyzed, 128 of whom had abdominal obesity and significantly higher LS than non-abdominally obese individuals. In the multivariate analysis, waist circumference was positively, independently, and significantly correlated with LS only in abdominally obese individuals. Conclusions: Liver stiffness by 2D-SWE could increase with increases in waist circumference in local citizens with abdominal obesity. Physicians should pay attention when assessing the LS of abdominally obese individuals.

The evaluation of the use of 2D shear-wave ultrasound elastography in differentiation of clinically insignificant and significant liver fibrosis in pediatric age group

OBJECTIVE

To determine the accuracy of 2D shear-wave elastography (2D-SWE) in pediatric age group patients in differentiating clinically insignificant and significant liver fibrosis using METAVIR fibrosis scoring system as the gold standard.

INTRODUCTION

Liver biopsy has long been the gold standard in liver fibrosis diagnosis. However, due to probable complications and sampling variabilities, the need for more accurate and non-invasive techniques has increased. 2D-SWE is a non-invasive technique used in the evaluation of liver stiffness and utilized more and more in routine clinical practice with recent advances and researches.

MATERIALS AND METHODS

In this retrospective single-center study, we included 46 pediatric age group patients who had a liver parenchymal biopsy and 2D-SWE evaluation regardless of etiology. For 2D-SWE, the LOGIQ E9 system (GE Medical Systems, Wisconsin, USA) and, for histopathological evaluation, METAVIR fibrosis scoring system were utilized. Patients were further subgrouped as clinically insignificant (METAVIR Score F0-1) and significant (METAVIR Score F2-4). The Kolmogorov-Smirnov and Mann-Whitney U tests were employed for statistical analysis. The diagnostic accuracy of 2D-SWE was assessed, and cutoff values were set by ROC curve analysis.

RESULTS

kPa values were statistically different between clinically significant and insignificant fibrosis patient groups (p < 0.001). kPa value of 8.92 was designated as the best cutoff value according to the Youden Index.

CONCLUSION

2D-SWE is one of the non-invasive techniques in the evaluation of liver fibrosis. Our findings suggest that 2D-SWE accurately differentiate clinically insignificant and significant liver fibrosis.

Liver Fibrosis and Steatosis in Alström Syndrome: A Genetic Model for Metabolic Syndrome

Alström syndrome (ALMS) is an ultra-rare monogenic disease characterized by insulin resistance, multi-organ fibrosis, obesity, type 2 diabetes mellitus (T2DM), and hypertriglyceridemia with high and early incidence of non-alcoholic fatty liver disease (NAFLD). We evaluated liver fibrosis quantifying liver stiffness (LS) by shear wave elastography (SWE) and steatosis using ultrasound sonographic (US) liver/kidney ratios (L/K) in 18 patients with ALMS and 25 controls, and analyzed the contribution of metabolic and genetic alterations in NAFLD progression. We also genetically characterized patients. LS and L/K values were significantly higher in patients compared with in controls (p < 0.001 versus p = 0.013). In patients, LS correlated with the Fibrosis-4 Index and age, while L/K was associated with triglyceride levels. LS showed an increasing trend in patients with metabolic comorbidities and displayed a significant correlation with waist circumference, the homeostasis model assessment, and glycated hemoglobin A1c. SWE and US represent promising tools to accurately evaluate early liver fibrosis and steatosis in adults and children with ALMS during follow-up. We described a new pathogenic variant of exon 8 in ALMS1. Patients with ALMS displayed enhanced steatosis, an early increased age-dependent LS that is associated with obesity and T2DM but also linked to genetic alterations, suggesting that ALMS1 could be involved in liver fibrogenesis.

Quantification of Liver Fibrosis, Steatosis, and Viscosity Using Multiparametric Ultrasound in Patients with Non-Alcoholic Liver Disease: A "Real-Life" Cohort Study

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. This study aimed to evaluate the performance of four ultrasound-based techniques for the non-invasive multiparametric (MPUS) assessment of liver fibrosis (LF), steatosis (HS), and inflammation in patients with NAFLD. We included 215 consecutive adult patients with NAFLD (mean age: 54.9 ± 11.7; 54.5% were male), in whom LF, HS, and viscosity were evaluated in the same session using four new ultrasound-based techniques embedded on the Aixplorer MACH 30 system: ShearWave Elastography (2D-SWE.PLUS), Sound Speed Plane-wave UltraSound (SSp.PLUS), Attenuation Plane-wave UltraSound (Att.PLUS), and Viscosity Plane-wave UltraSound (Vi.PLUS). Transient Elastography (TE) with Controlled Attenuation Parameter (CAP) (FibroScan) were considered as control. All elastographic measurements were performed according to guidelines. Valid liver stiffness measurements (LSM) were obtained in 98.6% of patients by TE, in 95.8% of patients by 2D-SWE.PLUS/Vi.PLUS, and in 98.1% of patients by Att.PLUS/SSp.PLUS, respectively. Therefore, 204 subjects were included in the final analysis. A strong correlation between LSMs by 2D-SWE.PLUS and TE (r = 0.89) was found. The best 2D-SWE.PLUS cut-off value for the presence of significant fibrosis (F ≥ 2) was 7 kPa. Regarding steatosis, SSp.PLUS correlated better than Att.PLUS with CAP values: (r = −0.74) vs. (r = 0.45). The best SSp.PLUS cut-off value for predicting the presence of significant steatosis was 1524 m/s. The multivariate regression analysis showed that Vi.PLUS values were associated with BMI and LSM by 2D-SWE.PLUS. In conclusion, MPUS was useful for assessing fibrosis, steatosis, and inflammation in a single examination in patients with NAFLD.

Follow-Up of Liver Stiffness with Shear Wave Elastography in Chronic Hepatitis C Patients in Sustained Virological Response Augments Clinical Risk Assessment

This study aimed to observe the effect of the direct-acting antiviral (DAA) therapy on liver stiffness (LS) and serum biomarkers. We prospectively observed 35 patients with chronic hepatitis C infection and attained a sustained virological response (SVR) after antiviral therapy. Shear wave elastography (SWE) measurement was performed at the beginning of DAA treatment and at 48 weeks after the end of treatment (EOT48w). The METAVIR score and the score for varices needing treatment (VNT) were determined based on the LS values; the fibrosis-4 (FIB4) score was calculated from laboratory tests. The baseline LS (mean ± standard deviation = 2.59 ± 0.89 m/s) decreased significantly after successful DAA therapy (1.90 ± 0.50 m/s; p < 0.001). The METAVIR score showed significant improvement at EOT48w (F0/1 = 9, F2 = 2, F3 = 10, F4 = 14) compared to the initial status (F0/1 = 2, F2 = 1, F3 = 7, F4 = 25; p < 0.028). The FIB4 score indicated less fibrosis after therapy (2.04 ± 1.12) than at baseline (3.51 ± 2.24; p < 0.018). Meanwhile, the number of patients with a high-risk of VNT was significantly less at EOT48w (4 vs. 15 at baseline; OR = 0.17 95% confidence interval (CI) = 0.05–0.59, p < 0.007). SWE indicates a significant resolution of liver fibrosis when chronic hepatitis C patients are in SVR, coinciding with a lower risk of VNT.

Establishing Reliability Criteria for Liver ElastPQ Shear Wave Elastography (ElastPQ-SWE): Comparison Between 10, 5 and 3 Measurements

PURPOSE

 ElastPQ is a new elastography technique for non-invasive liver fibrosis staging. However, it does not have validated reliability criteria. We tested the reliability of a different number of measurements in patients with chronic liver disease and explored whether the application of quality criteria improves the diagnostic performance.

MATERIALS AND METHODS

 All patients underwent liver stiffness assessment (LSM) with ElastPQ and Fibroscan (F-TE). The mean, median, standard deviation (SD) and interquartile range (IQR) of 10, 5 and 3 measurements were retrospectively collected for each patient and compared to each other. Liver histology was available in a subset of patients.

RESULTS

 Overall, 400 patients met the inclusion criteria. Non-alcoholic fatty liver disease (NAFLD) was the most represented etiology (75 %), followed by primary sclerosing cholangitis (PSC), primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH). The correlation of medians was significantly better between 10 and 5 measurements than between 10 and 3. The difference of medians was significant only in the comparison between 10 and 3 measurements. The correlation between ElastPQ and F-TE was equally good for 10 and 5 measurements and significantly improved after an IQR/median ≤ 30 % was applied. The diagnostic performance of ElastPQ was better with the median value of 10 and 5 measurements and improved if LSM values were obtained with IQR/M ≤ 30 %.

CONCLUSION

 The median value of 5 valid LSMs suffices for the reliable estimation of liver stiffness using ElastPQ. The quality criterion of IQR/M ≤ 30 % should also be followed when using this technique.

Comparison of preoperative two-dimensional shear wave elastography, indocyanine green clearance test and biomarkers for post hepatectomy liver failure prediction in patients with hepatocellular carcinoma

Background

The preoperative prediction of post hepatectomy liver failure (PHLF) is essential, but there is no gold standard for the prediction at present, and the efficacy of different methods for the prediction has not been compared systematically. In this study, we aimed to compare the efficacy of preoperative two-dimensional shear wave elastography (2D-SWE), indocyanine green (ICG) clearance test and biomarkers for PHLF prediction in patients with hepatocellular carcinoma (HCC).

Methods

We retrospectively studied 215 patients with HCC, who had undergone major liver resection in our hospital. Preoperative data of each patient, including liver stiffness value (LSV) of underlying hepatic parenchyma measured by 2D-SWE, ICG retention rate at 15 min (ICG-R15) measured by ICG clearance test, albumin-bilirubin (ALBI) scores, aspartate aminotransferase–platelet ratio index (APRI), and Fibrosis-4 (FIB-4) were collected for analysis. Post hepatectomy outcomes of study patients were also recorded for assessment of PHLF. The study patients were divided into development cohort (133 patients without PHLF, and 17 patients with PHLF) and validation cohort (59 patients without PHLF, and 6 patients with PHLF) randomly.

Results

In the development cohort, LSV, ICG-R15 and ALBI scores were significantly different between patients with and without PHLF, while no significant difference of APRI and FIB-4 scores was found. LSV had higher AUC (the area under the receiver operating characteristic curve) (AUC = 0.795) for PHLF prediction than ICG-R15 (AUC = 0.619) and ALBI scores (AUC = 0.686) (p < 0.05 for all comparisons). In the validation cohort, the cutoff value of LSV obtained from the development cohort, 10.35 kPa,  revealed higher specificity (76.3%) for PHLF prediction than ICG-R15 (specificity: 66.1%) and ALBI scores (specificity: 69.5%) (p < 0.0001).

Conclusions

Compared with ICG-R15, ALBI scores, APRI and FIB-4, LSV measured by 2D-SWE may demonstrate better efficacy for preoperative PHLF prediction in patients with HCC.

Microscope-Based Automated Quantification of Liver Fibrosis in Mice Using a Deep Learning Algorithm

In preclinical studies that involve animal models for hepatic fibrosis, accurate quantification of the fibrosis is of utmost importance. The use of digital image analysis based on deep learning artificial intelligence (AI) algorithms can facilitate accurate evaluation of liver fibrosis in these models. In the present study, we compared the quantitative evaluation of collagen proportionate area in the carbon tetrachloride model of liver fibrosis in the mouse by a newly developed AI algorithm to the semiquantitative assessment of liver fibrosis performed by a board-certified toxicologic pathologist. We found an excellent correlation between the 2 methods of assessment, most evident in the higher magnification (×40) as compared to the lower magnification (×10). These findings strengthen the confidence of using digital tools in the toxicologic pathology field as an adjunct to an expert toxicologic pathologist.

Efficacy of shear wave elastography for assessment of liver function in patients with heart failure

AIMS

Liver dysfunction is important for prognosis in heart failure (HF). Shear wave elastography (SWE), which is a novel ultrasound technique for charactering tissues, has been used in liver diseases. However, clinical implication of SWE, including dispersion slope, remains unknown in heart diseases. This study aimed to evaluate the efficacy of SWE assessing liver function in the severity of HF.

METHODS AND RESULTS

We enrolled 316 consecutive patients with or suspected heart diseases, who were classified according to the American College of Cardiology Foundation/American Heart Association stage of HF, including 37 with Stage A, 139 with Stage B, 114 with Stage C, and 26 with Stage D, and 45 normal subjects. Elasticity and dispersion slope of shear wave were assessed according to the HF stage. Elasticity and dispersion slope were not elevated in normal subjects and patients with Stage A. Elasticity was slightly increased from Stage A to Stage C and was remarkably elevated in Stage D (normal: 5.2 ± 1.1 kPa, Stage A: 5.4 ± 1.2 kPa, Stage B: 6.4 ± 1.8 kPa, Stage C: 7.8 ± 3.5 kPa, and Stage D: 17.7 ± 12.7 kPa), whereas dispersion slope was gradually increased from Stage A to Stage D (normal: 9.7 ± 1.7m/s/kHz, Stage A: 10.4 ± 1.6m/s/kHz, Stage B: 11.7 ± 2.4m/s/kHz, Stage C: 13.2 ± 3.4m/s/kHz, and Stage D: 17.6 ± 5.6 m/s/kHz). In the early HF stage, dispersion slope was elevated. In the advanced HF stage, both elasticity and dispersion slope were elevated. Liver function test abnormalities were observed only from Stage C or Stage D.

CONCLUSIONS

Dispersion slope could detect early liver damage, and the combination of elasticity and dispersion slope could clarify the progression of liver dysfunction in HF. SWE may be valuable to manage therapeutic strategies in patients with HF.

Non-invasive imaging biomarkers to assess nonalcoholic fatty liver disease: A review

This review summarizes the current state of non-invasive diagnosis of non-alcoholic fatty liver disease (NAFLD). This begins with a brief discussion of blood-based analysis (serum biomarkers) then progresses through various imaging modalities (imaging biomarkers) including magnetic resonance (MR), computed tomography (CT), and ultrasound-based imaging methods. The review concludes with comment on the advantages, disadvantages, and prospects of commercially available modalities and the impact they may have on diagnosis and management of patients with NAFLD.

Elastografía en tiempo real (Supersonic), experiencia de un centro en Bogotá

Introducción: la elastografía en tiempo real, 2D-SWE (Supersonic), es una prueba no invasiva que se utiliza para determinar la elasticidad del hígado y, de esa forma, calcular el grado de fibrosis hepática. En Colombia, la prueba se introdujo en 2016 y no existen hasta el momento estudios del comportamiento de la prueba en todos los pacientes hepáticos, solo se han publicado en pacientes sanos y cirróticos. Objetivo: analizar la experiencia de la aplicación de la elastografía en tiempo real, en sujetos atendidos en el centro de enfermedades hepáticas y digestivas de Bogotá, Colombia. Materiales y métodos: estudio descriptivo retrospectivo de una cohorte de sujetos atendidos entre marzo de 2016 y julio de 2017. Se realizó una historia clínica completa y una prueba de elastografía en tiempo real (Supersonic). Resultados: se incluyeron 654 sujetos, con una mediana de edad de 55 años (rango intercuartílico [RIC]: 45-64). La mediana de valores de fibrosis expresada en kilopascales (kPs) fue de 8,3, con un promedio de 5 mediciones. Se observó una diferencia significativa en el grado de fibrosis entre los grupos de edad y en relación con el diagnóstico final, donde se evidenció una mayor fibrosis en el grupo de enfermedades colestásicas (autoinmune, colangitis biliar primaria [CBP] y superposición autoinmune-CBP). La tasa global de fracaso fue menor al 1 %. Conclusiones: es la primera descripción del comportamiento de la prueba a nivel nacional. Los valores de rigidez hepática observados en los diferentes estadios demuestran la utilidad de la prueba para la determinación de la fibrosis hepática en pacientes con diferentes patologías.

Comparison of 2-D Shear Wave Elastography and Point Shear Wave Elastography for Assessing Liver Fibrosis

Progressive liver fibrosis may result in cirrhosis, portal hypertension and increased risk of hepatocellular carcinoma. We performed a meta-analysis to compare liver fibrosis staging in chronic liver disease patients using 2-D shear wave elastography (2-D SWE) and point shear wave elastography (pSWE). The PubMed, Web of Science and Cochrane Library databases were searched until May 31, 2020 for studies evaluating the diagnostic performance of 2-D SWE and pSWE in assessing liver fibrosis. Pooled sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratios and area under receiver operating characteristic curve were estimated using the bivariate random effects model. As a result, 71 studies with 11,345 patients were included in the analysis. The pooled sensitivities of 2-D SWE and pSWE significantly differed for the detection of significant fibrosis (F ≥ 2; 0.84 vs. 0.76, p < 0.001) and advanced fibrosis (F ≥ 3; 0.90 vs. 0.83, p = 0.003), but not for detection of cirrhosis (F = 4; 0.89 vs. 0.85, p = 0.090). The pooled specificities of 2-D SWE and pSWE did not significantly differ for detection of F ≥ 2 (0.81 vs. 0.79, p = 0.753), F ≥ 3 (0.87 vs. 0.83, p = 0.163) or F = 4 (0.87 vs. 0.84, p = 0.294). Both 2-D SWE and pSWE have high sensitivity and specificity for detecting each stage of liver fibrosis. Two-dimensional SWE has higher sensitivity than pSWE for detection of significant fibrosis and advanced fibrosis.

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.

Matrix stiffness and shear stresses modulate hepatocyte functions in a fibrotic liver sinusoidal model

Extracellular matrix (ECM) rigidity has important effects on cell behaviors and increases sharply in liver fibrosis and cirrhosis. Hepatic blood flow is essential in maintaining hepatocytes' (HCs) functions. However, it is still unclear how matrix stiffness and shear stresses orchestrate HC phenotype in concert. A fibrotic three-dimensional (3-D) liver sinusoidal model is constructed using a porous membrane sandwiched between two polydimethylsiloxane (PDMS) layers with respective flow channels. The HCs are cultured in collagen gels of various stiffnesses in the lower channel, whereas the upper channel is pre-seeded with liver sinusoidal endothelial cells (LSECs) and accessible to shear flow. The results reveal that HCs cultured within stiffer matrices exhibit reduced albumin production and cytochrome P450 (CYP450) reductase expression. Low shear stresses enhance synthetic and metabolic functions of HC, whereas high shear stresses lead to the loss of HC phenotype. Furthermore, both mechanical factors regulate HC functions by complementing each other. These observations are likely attributed to mechanically induced mass transport or key signaling molecule of hepatocyte nuclear factor 4α (HNF4α). The present study results provide an insight into understanding the mechanisms of HC dysfunction in liver fibrosis and cirrhosis, especially from the viewpoint of matrix stiffness and blood flow.NEW & NOTEWORTHY A fibrotic three-dimensional (3-D) liver sinusoidal model was constructed to mimic different stages of liver fibrosis in vivo and to explore the cooperative effects of matrix stiffness and shear stresses on hepatocyte (HC) functions. Mechanically induced alterations of mass transport mainly contributed to HC functions via typical mechanosensitive signaling.

The Feasibility of Cervical Elastography in Predicting Preterm Delivery in Singleton Pregnancy with Short Cervix Following Progesterone Treatment

Previous studies demonstrated an association between cervical strain and risk of spontaneous preterm delivery (sPTD). The present study aimed to assess the efficacy of elastography in predicting sPTD at <32 weeks of gestation in women with singleton pregnancies receiving progesterone for short cervix (≤2.5 cm) diagnosed between 16 and 28 weeks of gestation Among 115 participants eligible for analysis, nine had sPTD at <32 weeks. Preprogesterone (PP0) mean internal os strain (IOS), elasticity contrast index (ECI), hardness ratio (HR), one-week postprogesterone (PP1) IOS, mean external os strain (EOS), ECI, and HR were significantly different between groups. Higher PP0 IOS, PP1 IOS, and PP1 EOS were associated with a 2.92, 4.39 and 3.65-fold increase in the risk of sPTD at <32 weeks, respectively (adjusted for cervical length (CL) at diagnosis; p = 0.04, 0.012 and 0.026, respectively). A combination of CL at diagnosis, PP0 IOS and PP1 EOS showed a significantly higher area under the receiver operating characteristic curve (0.858) than that of CL alone (p = 0.041). In women with singleton pregnancies receiving progesterone for short cervix, cervical elastography performed before and one week after progesterone treatment may be useful in predicting sPTD at <32 weeks of gestation.

Efficacy of shear wave elastography for evaluating right ventricular myocardial fibrosis in monocrotaline-induced pulmonary hypertension rats

BACKGROUND

Right ventricular (RV) function is important for outcomes in pulmonary hypertension. Evaluation of RV myocardial characteristics is useful to assess the disease severity. Shear wave elastography (SWE) provides information of shear wave (SW) elasticity, which is related to tissue hardness, and SW dispersion slope, which reflects tissue viscosity. This study aimed to test the hypothesis that SW elasticity is increased and SW dispersion slope is decreased in the right ventricle of monocrotaline (MCT)-induced pulmonary hypertension rats.

METHODS

Rats were divided into MCT-induced pulmonary hypertension group (n = 10) and control group (n = 10). SW elasticity and SW dispersion slope were measured on excised hearts. Myocardial fibrosis was evaluated histologically.

RESULTS

RV hypertrophy was observed in the MCT group. SW elasticity of right ventricle was higher in the MCT group than in the control group (3.5 ± 0.9 kPa vs. 2.5 ± 0.4 kPa, p < 0.01). SW dispersion slope of right ventricle was lower in the MCT group than in the control group (5.3 ± 1.7 m/s/kHz vs. 7.7 ± 1.5 m/s/kHz, p < 0.01). The fibrosis area of right ventricle was increased in MCT group compared with control group (18 ± 5% vs. 8 ± 3%, p < 0.01), and was positively related to SW elasticity and negatively related to SW dispersion slope.

CONCLUSIONS

Higher SW elasticity and lower SW dispersion slope were observed in the fibrotic myocardium of right ventricle in MCT-induced pulmonary hypertension rats. SWE may have the potential to evaluate RV function by assessing myocardial characteristics.

DSWE-Net: A deep learning approach for shear wave elastography and lesion segmentation using single push acoustic radiation force

Ultrasound-based non-invasive elasticity imaging modalities have received significant consideration for tissue characterization over the last few years. Though substantial advances have been made, the conventional Shear Wave Elastography (SWE) methods still suffer from poor image quality in regions far from the push location, particularly those which rely on single focused ultrasound push beam to generate shear waves. In this study, we propose DSWE-Net, a novel deep learning-based approach that is able to construct Young's modulus maps from ultrasonically tracked tissue velocity data resulting from a single acoustic radiation force (ARF) push. The proposed network employs a 3D convolutional encoder, followed by a recurrent block consisting of several Convolutional Long Short-Term Memory (ConvLSTM) layers to extract high-level spatio-temporal features from different time-frames of the input velocity data. Finally, a pair of coupled 2D convolutional decoder blocks reconstructs the modulus image and additionally performs inclusion segmentation by generating a binary mask. We also propose a multi-task learning loss function for end-to-end training of the network with 1260 data samples obtained from a simulation environment which include both bi-level and multi-level phantom structures. The performance of the proposed network is evaluated on 140 synthetic test data and the results are compared both qualitatively and quantitatively with that of the current state of the art method, Local Phase Velocity Based Imaging (LPVI). With an average SSIM of 0.90, RMSE of 0.10 and 20.69 dB PSNR, DSWE-Net performs much better on the imaging task compared to LPVI. Our method also achieves an average IoU score of 0.81 for the segmentation task which makes it suitable for localizing inclusions as well. In this initial study, we also show that our method gains an overall improvement of 0.09 in SSIM, 4.81 dB in PSNR, 2.02 dB in CNR, and 0.09 in RMSE over LPVI on a completely unseen set of CIRS tissue mimicking phantom data. This proves its better generalization capability and shows its potential for use in real-world clinical practice.

Two-Dimensional Shear Wave Elastography Predicts Liver Fibrosis in Jaundiced Infants with Suspected Biliary Atresia: A Prospective Study

Objective

This study aimed to evaluate the role of preoperative two-dimensional (2D) shear wave elastography (SWE) in assessing the stages of liver fibrosis in patients with suspected biliary atresia (BA) and compared its diagnostic performance with those of serum fibrosis biomarkers.

Materials and Methods

This study was approved by the ethical committee, and written informed parental consent was obtained. Two hundred and sixteen patients were prospectively enrolled between January 2012 and October 2018. The 2D SWE measurements of 69 patients have been previously reported. 2D SWE measurements, serum fibrosis biomarkers, including fibrotic markers and biochemical test results, and liver histology parameters were obtained. 2D SWE values, serum biomarkers including, aspartate aminotransferase to platelet ratio index (APRi), and other serum fibrotic markers were correlated with the stages of liver fibrosis by METAVIR. Receiver operating characteristic (ROC) curves and area under the ROC (AUROC) curve analyses were used.

Results

The correlation coefficient of 2D SWE value in correlation with the stages of liver fibrosis was 0.789 (p < 0.001). The cut-off values of 2D SWE were calculated as 9.1 kPa for F1, 11.6 kPa for F2, 13.0 kPa for F3, and 15.7 kPa for F4. The AUROCs of 2D SWE in the determination of the stages of liver fibrosis ranged from 0.869 to 0.941. The sensitivity and negative predictive value of 2D SWE in the diagnosis of ≥ F3 was 93.4% and 96.0%, respectively. The diagnostic performance of 2D SWE was superior to that of APRi and other serum fibrotic markers in predicting severe fibrosis and cirrhosis (all p < 0.005) and other serum biomarkers. Multivariate analysis showed that the 2D SWE value was the only statistically significant parameter for predicting liver fibrosis.

Conclusion

2D SWE is a more effective non-invasive tool for predicting the stage of liver fibrosis in patients with suspected BA, compared with serum fibrosis biomarkers.

Non-invasive assessment of skeletal muscle fibrosis in mice using nuclear magnetic resonance imaging and ultrasound shear wave elastography

Fibrosis is a key pathological feature in muscle disorders, but its quantification mainly relies on histological and biochemical assays. Muscle fibrosis most frequently is entangled with other pathological processes, as cell membrane lesions, inflammation, necrosis, regeneration, or fatty infiltration, making in vivo assessment difficult. Here, we (1) describe a novel mouse model with variable levels of induced skeletal muscle fibrosis displaying minimal inflammation and no fat infiltration, and (2) report how fibrosis affects non-invasive metrics derived from nuclear magnetic resonance (NMR) and ultrasound shear-wave elastography (SWE) associated with a passive biomechanical assay. Our findings show that collagen fraction correlates with multiple non-invasive metrics. Among them, muscle stiffness as measured by SWE, T₂, and extracellular volume (ECV) as measured by NMR have the strongest correlations with histology. We also report that combining metrics in a multi-modality index allowed better discrimination between fibrotic and normal skeletal muscles. This study demonstrates that skeletal muscle fibrosis leads to alterations that can be assessed in vivo with multiple imaging parameters. Furthermore, combining NMR and SWE passive biomechanical assay improves the non-invasive evaluation of skeletal muscle fibrosis and may allow disentangling it from co-occurring pathological alterations in more complex scenarios, such as muscular dystrophies.

Noninvasive Staging of Liver Fibrosis Using 5-Minute Delayed Dual-Energy CT: Comparison with US Elastography and Correlation with Histologic Findings

Background Normalized iodine concentration (NIC) (ratio of iodine concentration of liver to that of aorta) of liver at delayed dual-energy CT (DECT) may reflect the amount of fibrosis based on the extent of iodine uptake. Purpose To stage liver fibrosis by using 5-minute delayed DECT and compare findings with those of transient elastography (TE), shear-wave elastography (SWE), and histologic examination. Materials and Methods This prospective study included patients with chronic liver disease who were scheduled to undergo multiphase abdominal CT and liver biopsy from January 2017 to September 2018. Fifty individuals being screened as renal donors comprised the control group. Study participants underwent TE, SWE, multiphasic DECT (including 5-minute delayed dual-energy scanning), and liver biopsy. Multiphasic DECT and SWE were performed in the control group. The NIC of the right lobe of the liver (RNIC) was compared with liver stiffness (LS) as measured with TE and SWE and with the METAVIR fibrosis stage (ranging from F0 to F4). Diagnostic performance was assessed by using areas under the receiver operating characteristic curve (AUCs). Results A total of 107 participants (mean age, 35 years ± 12 [standard deviation]; 57 men) and 50 control subjects (mean age, 47 years ± 11; 29 women) were evaluated. The RNIC showed strong correlation with METAVIR stage (Spearman ρ = 0.81, P < .001). The AUC for RNIC with each METAVIR stage ranged between 0.86 (95% CI: 0.76, 0.97) and 0.96 (95% CI: 0.92, 0.99). The cut-off value of RNIC was 0.24 (sensitivity: 85% [86 of 101 participants; 95% CI: 77%, 91%]; specificity: 83% [84 of 101 participants; 95% CI: 42%, 98%]) for stage F1 fibrosis and 0.29 (sensitivity: 84% [67 of 80 participants; 95% CI: 74%, 90%]; specificity: 81% [65 of 80 participants; 95% CI: 63%, 92%]) for stage F2 fibrosis. RNIC correlated well with LS as measured with TE and SWE (Spearman ρ = 0.60 and 0.64, respectively; P < .001). Conclusion Normalized iodine concentration of liver at 5-minute delayed dual-energy CT showed strong correlation with the histologic stages of liver fibrosis and good diagnostic performance in estimating liver fibrosis. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Chandarana and Shanbhogue in this issue.

Performance and cutoffs for liver fibrosis staging of a two-dimensional shear wave elastography technique

OBJECTIVES

To assess performance and cutoffs of the 2-dimensional shear wave elastography technique available on the Aplio i800 ultrasound system (Canon Medical Systems, Japan), using transient elastography as reference standard, and to assess the correlation of shear-wave-speed dispersion with liver fibrosis or steatosis.

METHODS

This was a single-center cross-sectional study. The correlations between values obtained with transient elastography and 2-dimensional-shear wave elastography, and between shear-wave-speed dispersion and fibrosis or steatosis, were assessed with Pearson's r. The diagnostic performance of the 2-dimensional-shear wave elastography for staging significant fibrosis and severe fibrosis compared to transient elastography was assessed using the area under the receiver operating characteristic curve analysis.

RESULTS

Three hundred sixty-seven patients (198 males and 169 females) were studied. There was a high correlation between 2-dimensional-shear wave elastography and transient elastography (r = 0.87, P < 0.0001). The area under the receiver operating characteristics of 2-dimensional-shear wave elastography for staging significant fibrosis (F2) and severe fibrosis (F3-F4), respectively, were 0.97 (95% confidence interval, 0.91-0.98) and 0.97 (95% confidence interval, 0.95-0.99). The best cutoffs for significant fibrosis and severe fibrosis, respectively, were > 7 and > 9 kPa. Shear-wave-speed dispersion showed a high correlation with fibrosis (r = 0.85, P < 0.0001), whereas there was a very weak correlation with steatosis.

CONCLUSIONS

The results of this study show that this 2-dimensional-shear wave elastography technique is accurate for staging liver fibrosis. Shear-wave-speed dispersion is highly correlated with liver fibrosis but not with steatosis.

Liraglutide reduces attenuation coefficient as a measure of hepatic steatosis during 16 weeks' treatment in nondiabetic obese patients: A pilot trial

Background and Aim

Liraglutide, a long-acting GLP-1 analog, is approved for the treatment of obesity with improvements in fasting blood glucose, hemoglobin A1c, and cardiovascular health. Our aim was to measure the impact of liraglutide dose for obesity on hepatic steatosis measured by ultrasound.

Methods

A single-center, randomized, double-blind, placebo-controlled pilot trial was undertaken in nondiabetic obese, otherwise healthy patients aged 18-65 years. Participants were randomly assigned to receive subcutaneous liraglutide (3.0 mg) or placebo over 16 weeks with dose escalation following US Food and Drug Administration guidelines. Both groups received standardized nutritional and behavioral counseling during the 16 weeks. Hepatic fat content was measured by ultrasound at baseline, 8 weeks, and 16 weeks as an attenuation coefficient (ACE). Effects of treatment were assessed using t-test for the entire groups and for patient subgroup with baseline ACE >0.66 (indicating significant steatosis).

Results

Among 30 patients (93% female) enrolled, 16 were randomized to placebo and 14 to liraglutide. Baseline body mass indices (BMIs) and average age were similar in the two groups. After 16 weeks, the liraglutide group had a significant improvement in steatosis ACE scores (-0.068 ± 0.02 vs -0.0077 ± 0.02 placebo, P = 0.05). Change in steatosis was positively correlated with change in BMI (R² = 0.402, P = 0.0007). Within the liraglutide group, patients with baseline ACE >0.66 had improvement in ACE (-0.134 ± 0.03) compared to those without significant steatosis (-0.041 ± 0.02, P = 0.05).

Conclusions

In this pilot trial, liraglutide, 3.0 mg over 16 weeks, reduced hepatic steatosis; a reduction in hepatic steatosis is correlated with BMI reduction, and effects are particularly evident in those with a significant degree of steatosis by ultrasound imaging.

The Use of Two-Dimensional Shear Wave Elastography in People with Obesity for the Assessment of Liver Fibrosis in Non-Alcoholic Fatty Liver Disease

Obesity is associated with significant comorbidities, including non-alcoholic fatty liver disease (NAFLD). Given its potential to progress to advanced liver disease, monitoring the extent and progress of liver fibrosis and assessing its fibrosis stage are essential. Although liver biopsy is considered to be the gold standard for liver fibrosis staging, it is an invasive procedure with risk of complications. Considering the rising prevalence of obesity and NAFLD globally, developing non-invasive diagnostic methods is a priority. Transient elastography (TE) is increasingly being used to assess the severity of liver disease. However, in the presence of severe obesity, the increased thickness of subcutaneous adipose tissue and changes in anatomy may affect its diagnostic accuracy. Two-dimensional shear wave elastography (2D-SWE) assesses the liver stiffness in real time along with simultaneous anatomic B-mode ultrasound imaging and allows selection of the region of interest. This would suggest that 2D-SWE has several advantages over TE in patients with severe obesity. The purpose of this review is to examine the current literature addressing the use of 2D-SWE in the assessment of liver fibrosis in patients with NAFLD. This review also examines the evidence on the use of 2D-SWE in patients with obesity and NAFLD and compares it to TE as a novel and non-invasive method of assessing liver fibrosis.

Liver stiffness quantification in biopsy-proven nonalcoholic fatty liver disease patients using shear wave elastography in comparison with transient elastography

Purpose

This study prospectively assessed the performance of liver stiffness measurements using point shear-wave elastography (p-SWE) in comparison with transient elastography (TE) in patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD).

Methods

Fifty-six consecutive adult patients with a histological diagnosis of NAFLD prospectively underwent TE and p-SWE on the same day. The median of 10 measurements (SWE-10), the first five (SWE-5), and the first three (SWE-3) measurements were analyzed for p-SWE. Liver biopsy was considered as the reference standard for liver fibrosis grade. Receiver operating characteristic (ROC) curves and areas under the ROC curves (AUROCs) were calculated to assess the performance of TE and p-SWE for the diagnosis of significant (F2-F4) and advanced fibrosis (F3-F4).

Results

Forty-six patients (27 men, 19 women; mean age, 54.7±9.1 years) had valid p-SWE and TE measurements. Twenty-seven patients (58.7%) had significant fibrosis and 18 (39.1%) had advanced fibrosis. For significant fibrosis, both SWE-10 (AUROC, 0.787; P=0.002) and SWE-5 (AUROC, 0.809; P=0.001) provided higher diagnostic performance than TE (AUROC, 0.719; P=0.016) and SWE-3 (AUROC, 0.714; P=0.021), albeit without statistical significance (P=0.301). For advanced fibrosis, SWE-5 showed higher diagnostic performance (AUROC, 0.809; P<0.001) than TE (AUROC, 0.799; P<0.001), SWE-10 (AUROC, 0.797; P<0.001), and SWE-3 (AUROC, 0.736; P=0.003), although the differences were not statistically significant (P=0.496). The optimal SWE-10 and SWE-5 cutoff values were ≥8.4 and ≥7.8 for significant fibrosis, and ≥9.1 and ≥8.8 for advanced fibrosis, respectively.

Conclusion

TE and p-SWE showed similar performance for the diagnosis of significant and advanced fibrosis in NAFLD patients.

The Role of Elastography in Non-Alcoholic Fatty Liver Disease

The most common liver disease in developing countries is non-alcoholic fatty liver disease (NAFLD). This involves the abnormal accumulation of lipids in the liver, the pathogenesis of the disease being related to dyslipidemia, obesity, insulin resistance and type 2 diabetes. Most often, the diagnosis of NAFLD is incidental, when performing routine blood tests or when performing a transabdominal ultrasound. The NAFLD spectrum ranges from simple forms of hepatic steatosis to the most advanced form of the disease, steatohepatitis (NASH), which in evolution can cause inflammation, fibrosis, cirrhosis of the liver and even liver cancer. For the evaluation of the prognosis and the clinical evolution, the most important parameter to define is the degree of liver fibrosis. Currently, the gold standard remains the liver biopsy, the differentiation between NAFLD and NASH being made only on the basis of histological analysis. However, liver biopsy is an invasive procedure, with numerous risks such as bleeding, lesions of the other organs and complications related to anesthesia, which significantly reduces its widespread use. Moreover, the risk of a false negative result and the increased costs of the procedure further limits its use in current practice. For this reason, non-invasive methods of evaluating the degree of liver fibrosis have gained ground in recent years. Imaging techniques such as elastography have shown promising results in evaluating and staging NAFLD. The aim of this article is to review the current status of the non-invasive tests for the assessment of NAFLD with a focus on the ultrasound-based elastography techniques.

Shear Wave Dispersion Predicts Liver Fibrosis and Adverse Outcomes in Patients with Heart Failure

Background: It has been recently reported that liver stiffness assessed by transient elastography reflects right atrial pressure (RAP) and is associated with worse outcomes in patients with heart failure (HF). However, the relationship between shear wave dispersion (SWD, a novel indicator of liver viscosity) determined by abdominal ultrasonography and RAP, and the prognostic impact of SWD on HF patients have not been fully examined. We aimed to clarify the associations of SWD with parameters of liver function test (LFT) and right heart catheterization (RHC), as well as with cardiac events such as cardiac death and worsening HF, in patients with HF. Methods: We performed abdominal ultrasonography, LFT and RHC in HF patients (n = 195), and followed up for cardiac events. We examined associations between SWD and parameters of LFT and RHC. Results: There were significant correlations between SWD and circulating levels of direct bilirubin (R = 0.222, p = 0.002), alkaline phosphatase (R = 0.219, p = 0.002), cholinesterase (R = −0.184, p = 0.011), and 7S domain of collagen type IV (R = 0.177, p = 0.014), but not with RAP (R = 0.054, p = 0.567) or cardiac index (R = −0.015, p = 0.872). In the Kaplan–Meier analysis, cardiac event rate was significantly higher in the high SWD group (SWD ≥ 10.0 (m/s)/kHz, n = 103) than in the low SWD group (SWD < 10.0 (m/s)/kHz, n = 92; log-rank, p = 0.010). In the Cox proportional hazard analysis, high SWD was associated with high cardiac event rates (hazard ratio, 2.841; 95% confidence interval, 1.234–6.541, p = 0.014). In addition, there were no interactions between SWD and all subgroups, according to the subgroup analysis. Conclusions: SWD assessed by abdominal ultrasonography reflects liver fibrosis rather than liver congestion, and is associated with adverse prognosis in HF patients.

What does liver elastography measure? Technical aspects and methodology

Elastography can be thought as an extension of the ancient technique of palpation. After giving a short introduction to the history of elastography, the different technologies that are nowadays available and the physics behind them, the article focuses on the assessment of liver stiffness in patients with diffuse liver disease using shear wave elastography (SWE). Practical advices on how to perform the SWE techniques and on the factors that should be considered for a correct interpretation of the results are given. This paper aimed to provide a practical guide for beginners and advanced clinical users to better understand technical aspects, methodologies and terminology.

Role of shear wave elastography in characterization of hepatic focal lesions

Background

Elastography is a recently developed diagnostic method that aims to evaluate tissue stiffness. Its utility is based on the fact that pathological tissues are generally stiffer than surrounding healthy tissues which often show up as a hard lesion. Shear wave elastography (SWE) is a new technique based on shear waves that has been implemented in diagnostic ultrasound (US) systems. The aim of this study is to study the role of shear wave elastography in differentiation between benign and malignant hepatic focal lesions.

Results

The study was conducted on 110 patients (92 males, 18 females) with a mean age of 51.7 years. Age range was from 30 to 70 years; 28 patients were diagnosed with benign lesions, and 82 with malignant lesions. SWE shows that there is a significant difference in stiffness between malignant and benign lesions with p value = 0.002 and with mean ± SD of 10.3 ± 6.31 kPa for the benign lesions and 16.2 ± 9.32 kPa for the malignant group. A cutoff value of 13.24 was selected to differentiate between benign and malignant lesions using the SWE mean providing sensitivity 78.04%, specificity 71.42%, and accuracy 64.2%.

Conclusion

SWE is a good tool in the differentiation of benign and malignant hepatic focal lesions.

Tumor stiffness measured by shear wave elastography correlates with tumor hypoxia as well as histologic biomarkers in breast cancer

Background

Shear wave elastography (SWE) is an ultrasound technique for the noninvasive quantification of tissue stiffness. The hypoxic tumor microenvironment promotes tumor stiffness and is associated with poor prognosis in cancer. We aimed to investigate the correlation between tumor hypoxia and histologic biomarkers and tumor stiffness measured by SWE in breast cancer.

Methods

From June 2016 to January 2018, 82 women with invasive breast cancer who underwent SWE before treatment were enrolled. Average tumor elasticity (E_average) and tumor-to-fat elasticity ratio (E_ratio) were extracted from SWE. Immunohistochemical staining of glucose transporter 1 (GLUT1) was used to assess tumor hypoxia in breast cancer tissues and automated digital image analysis was performed to assess GLUT1 activities. Spearman correlation and logistic regression analyses were performed to identify associations between GLUT1 expression and SWE values, histologic biomarkers, and molecular subtypes. The Mann–Whitney U test, t test, or Kruskal–Wallis test was used to compare SWE values and histologic features according to the GLUT1 expression (≤the median vs > median).

Results

E_average (r = 0.676) and E_ratio (r = 0.411) correlated significantly with GLUT1 expression (both p <  0.001). E_average was significantly higher in cancers with estrogen receptor (ER)–, progesterone receptor (PR)–, Ki67+, and high-grade (p <  0.05). E_ratio was higher in cancers with Ki67+, lymph node metastasis, and high-grade (p <  0.05). Cancers with high GLUT1 expression (>median) had higher E_average (mean, 85.4 kPa vs 125.5 kPa) and E_ratio (mean, 11.7 vs 17.9), and more frequent ER– (21.7% vs 78.3%), PR– (26.4% vs 73.1%), Ki67+ (31.7%% vs 68.3%), human epidermal growth factor receptor 2 (HER2) + (25.0% vs 75.0%), high-grade (28.6% vs 71.4%), and HER2-overexpressing (25.0% vs 75.0%) and triple-negative (23.1% vs 76.9%) subtypes (p <  0.05). Multivariable analysis showed that E_average was independently associated with GLUT1 expression (p <  0.001).

Conclusions

Tumor stiffness on SWE is significantly correlated with tumor hypoxia as well as histologic biomarkers. In particular, E_average on SWE has independent prognostic significance for tumor hypoxia in the multivariable analysis and can potentially be used as a noninvasive imaging biomarker to predict prognosis and pretreatment risk stratification in breast cancer patients.

Shear wave elastography for evaluation of the urgency of liver transplantation in pediatric patients with biliary atresia

BACKGROUND

To investigate the role of two-dimensional shear wave elastography (2D-SWE) in the preoperative evaluation of pediatric patients with biliary atresia awaiting liver transplantation.

METHODS

Among a total of 152 pediatric patients enrolled in this single-institution prospective study between March 2018 and August 2019, 143 patients (age range, 4-97 months; median age, 7 months; 84 males, 59 females) who underwent successful routine ultrasound examination, SWE examination, and blood test before liver transplantation were included in the final analysis. The values of liver stiffness measured by SWE were compared with ultrasound and blood test parameters by Spearman's correlation analysis.

RESULTS

The overall median liver stiffness with 2D-SWE was 29.0 ± 10.9 kPa, with a range of 9.0-53.3 kPa. The success rate of 2D-SWE measurements was 98.0% (149/152). Liver stiffness measurement (LSMs) had no significant correlation with gender, age, weight, and height of the pediatric recipients. LSMs were correlated with ultrasound parameters including portal vein (PV) maximum velocity, PV direction, hepatic artery resistance index (HARI), spleen diameter, ascites, and blood test parameters (albumin level, platelet count level, and international normalized ratio). In the pediatric recipients with hepatofugal PV flow, high HARI (HARI ≧ 0.90), and ascites, or without Kasai operation, LSMs were significantly higher (P < .05).

CONCLUSIONS

SWE is feasible and valuable for assessing liver damage in children with biliary atresia awaiting liver transplantation and might be used as selection criteria for children in need of priority access to liver transplantation.

Noninvasive scores for the prediction of esophageal varices and risk stratification in patients with cirrhosis

The primary purpose of variceal screening in patients with cirrhosis is to detect gastroesophageal varices at high risk of hemorrhage and implement preventative intervention(s). It was previously recommended that all patients with cirrhosis undergo initial and periodic longitudinal variceal screening via upper endoscopy. However, there has been growing interest and methods to identify patients with cirrhosis who may not have clinically significant portal hypertension and therefore be unlikely to have varices requiring intervention or benefit from upper endoscopy. Because the population of patients with compensated advanced chronic liver disease continues to grow, it is neither beneficial nor cost-effective to perform endoscopic variceal screening in all patients. Therefore, there is ongoing research into the development of methods to non-invasively risk stratify patients with cirrhosis for the presence of high-risk esophageal varices and effectively limit the population that undergoes endoscopic variceal screening. This is particularly important and timely in light of increasing healthcare reform and barriers to healthcare. In this review, we discuss and compare, with respect to test characteristics and clinical applicability, the available methods used to non-invasively predict the presence of esophageal varices.

The impact of bariatric surgery on nonalcoholic fatty liver disease as measured using non-invasive tests

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is common in bariatric surgery candidates. We evaluated the effect of sleeve gastrectomy (SG) on NAFLD using validated non-invasive measures.

METHODS

Patients with morbid obesity and NAFLD, planned for SG, were evaluated before and after surgery. Data collected included anthropometrics, biochemistry, adiponectin, SteatoTest™, NashTest™, FibroTest™, OWLiver® test and real-time ShearWave™ elastography (SWE).

RESULTS

Twenty-six subjects were included in the study, mean age 44.1 ± 4.8 years, 69.2% males. One year following SG, body mass index decreased significantly from 41.7 ± 4.8 kg/m² to 29.6 ± 4.5 kg/m². Concomitantly, significant improvements in triglycerides, ALT, diabetes markers and adiponectin were observed. Mean steatosis, as measured by SteatoTest™, was significantly improved. Steatohepatitis score measured by NashTest™ and OWLiver® significantly decreased. Mean fibrosis, as measured by SWE liver stiffness and FibroTest™, did not change over time.

CONCLUSION

Steatosis and steatohepatitis are significantly improved by SG as measured by non-invasive measures.

2-D Shear Wave Elastography for the Evaluation of Liver Fibrosis in Hepatosplenic Schistosomiasis: Reliability of a Single Measurement and Inter-Hepatic Lobe Variability

Data on liver and spleen stiffness by 2-D shear wave elastography (2-D SWE) in hepatosplenic schistosomiasis (HES) remain scarce. We aimed to assess the correlation between single to multiple measurements of liver and spleen stiffness and to evaluate inter-hepatic lobe variability of liver stiffness measurement (LSM) using 2-D SWE in HES patients. Liver and spleen elastography were performed in HES patients in this cross-sectional study. A total of four stiffness measurements were performed in the right lobe (RL), left lobe (LL), and spleen. The correlation between the first measurement and the median of four measurements was assessed. Liver stiffness measurement of both hepatic lobes was compared. Twenty-six HES patients were included. Liver stiffness measurement was higher in the left than in the right hepatic lobe (17.9 kPa [11.3-92.0] versus 14.9 kPa [5.6-44.4]; P = 0.019). The first measurement was similar to the median of the four measurements for the RL (14.6 [5.6-60.8] versus 14.9 kPa [5.6-44.4]; P = 0.87), LL (17.4 [8.0-128.1] versus 17.9 kPa [11.3-92.0]; P = 0.54), and spleen (50.5 [10.0-157.0] versus 55.7 kPa [19.1-119.4]; P = 0.48). An excellent correlation between the first measurement and the median of four measurements for the RL (r = 0.93; P < 0.001), LL (r = 0.88; P < 0.001), and spleen (r = 0.89; P < 0.001) was observed. In HES, LSM of the LL seems to be higher than that of the right hepatic lobe. Considering the excellent correlation between the first measurement and the median of four measurements in both hepatic lobes and spleen, a single measurement would be sufficient to evaluate liver and splenic stiffness in patients with HES.

Ultrasonographic cystometry for neurogenic bladder using elastography

AIM

Ultrasound shear wave elastography (SWE) has been used to measure elasticity (Young's modulus: YM) in solid organs. It was reported to show a better correlation with intravesical pressure (Pves) than with compliance, supporting its potential use in noninvasive cystometry. Contrariwise, conceptually, YM should be more correlated with compliance than with Pves. To optimize the potential use of YM as a noninvasive urodynamic study, the relationship between YM, Pves, and compliance was reassessed in this study.

METHOD

YM was serially measured using SWE along with bladder filling. To overcome problems inherent to current compliance measurements, modified dynamic compliance was developed from cystometry by a locally weighted scatter plot smoothing algorithm. Then it was matched with YM from SWE. YM was also correlated with Pves. Furthermore, to understand the nature of YM, which was measured by ultrasound, the bladder wall's modulus, which was the mathematical assessment of YM derived from cystometric data, was also calculated and compared.

RESULTS

Thirty-two neurogenic bladder patients were included in this study. YM correlated with Pves (r = .72, p < .0001) better than with modified dynamic compliance (r = -0.43, p < .0001). The correlation of YM with Pves was even higher than that with the calculated bladder wall's modulus (r = .52, p < .0001).

CONCLUSION

YM measured by SWE associates with Pves better than with compliance, confirming the results of previous studies. SWE reflects the integration of both the holding capability of the bladder wall and urine rather than either of one, implying its potential utilization in noninvasive cystometry.

Deep learning networks on chronic liver disease assessment with fine-tuning of shear wave elastography image sequences

Chronic liver disease (CLD) is currently one of the major causes of death worldwide. If not treated, it may lead to cirrhosis, hepatic carcinoma and death. Ultrasound (US) shear wave elastography (SWE) is a relatively new, popular, non-invasive technique among radiologists. Although many studies have been published validating the SWE technique either in a clinical setting, or by applying machine learning on SWE elastograms, minimal work has been done on comparing the performance of popular pre-trained deep learning networks on CLD assessment. Currently available literature reports suggest technical advancements on specific deep learning structures, with specific inputs and usually on a limited CLD fibrosis stage class group, with limited comparison on competitive deep learning schemes fed with different input types. The aim of the present study is to compare some popular deep learning pre-trained networks using temporally stable and full elastograms, with or without augmentation as well as propose suitable deep learning schemes for CLD diagnosis and progress assessment. 200 liver biopsy validated patients with CLD, underwent US SWE examination. Four images from the same liver area were saved to extract elastograms and processed to exclude areas that were temporally unstable. Then, full and temporally stable masked elastograms for each patient were separately fed into GoogLeNet, AlexNet, VGG16, ResNet50 and DenseNet201 with and without augmentation. The networks were tested for differentiation of CLD stages in seven classification schemes over 30 repetitions using liver biopsy as the reference. All networks achieved maximum mean accuracies ranging from 87.2%-97.4% and area under the receiver operating characteristic curves (AUCs) ranging from 0.979-0.990 while the radiologists had AUCs ranging from 0.800-0.870. ResNet50 and DenseNet201 had better average performance than the other networks. The use of the temporal stability mask led to improved performance on about 50% of inputs and network combinations while augmentation led to lower performance for all networks. These findings can provide potential networks with higher accuracy and better setting in the CLD diagnosis and progress assessment. A larger data set would help identify the best network and settings for CLD assessment in clinical practice.

The Performance of a 2-Dimensional Shear-Wave Elastography Technique for Predicting Different Stages of Liver Fibrosis Using Transient Elastography as the Control Method

ABSTRACT

The aim was to evaluate the performance of 2-dimensional (2D) shear-wave elastography from general electric (2D SWE-GE), implemented on the new LOGIQ S8 system, for the noninvasive assessment of liver fibrosis, and to identify liver stiffness (LS) cutoff values for predicting different stages of fibrosis using transient elastography (TE) as the control method. We included 179 consecutive subjects, with or without chronic hepatopathies, in whom LS was evaluated in the same session using 2 elastographic techniques: TE (FibroScan, EchoSens) and 2D SWE-GE (LOGIQ S8; GE Healthcare, Chalfont St Giles, United Kingdom). Reliable LS measurements were defined for TE: the median value of 10 measurements with a success rate of 60% or greater and an interquartile range/median ratio (IQR/M) < 0.30; for 2D SWE-GE: the median value of 10 measurements acquired in a homogenous area and IQR/M < 0.30. To discriminate between fibrosis stages by TE, we used the following cutoffs: F2-7; F3-9.5 and F4-12 kPa. Reliable LS measurements were obtained in 97.2% subjects by 2D SWE-GE and in 98.3% by TE (P = 0.72), so that 171 subjects were included for the final analysis. A good correlation was found between the LS values obtained by the 2 methods (r = 0.72, P < 0.0001). The best 2D SWE-GE cutoff value for F ≥ 2 was 6.9 kPa (areas under receiver operating characteristic [AUROC], 0.93; sensitivity, 85.8%; specificity, 90.2%), for F of 3 or greater, it was 8.2 kPa (AUROC, 0.93; sensitivity, 87.5%; specificity, 86.8%) and for F value of 4, it was 9.3 kPa (AUROC, 0.91; sensitivity, 85.7%; specificity, 81.2%). In conclusion, the best 2D SWE-GE (S8) cutoff values for predicting F2, F ≥ 3 and F = 4 were 6.9, 8.2, and 9.3 kPa.

Imaging biomarkers of diffuse liver disease: current status

We are happy to introduce this special issue of Abdominal Radiology on "diffuse liver disease". We have invited imaging experts to discuss various topics pertaining to diffuse liver disease, covering a vast array of imaging techniques including ultrasound (US), CT, MRI and new molecular imaging agents. Below, we briefly discussed the current status, limitations, and future directions of imaging biomarkers of diffuse liver disease.

Comparative Study Between the Diagnostic Performance of Point and 2-D Shear-Wave Elastography for the Non-invasive Assessment of Liver Fibrosis in Patients With Chronic Hepatitis C Using Transient Elastography as Reference

The study compared the diagnostic performance of two shear-wave elastography techniques, elastography point quantification (ElastPQ) and 2-D shear-wave elastography by General Electric (2-D-SWE.GE), for the non-invasive assessment of liver fibrosis in a cohort of patients with chronic hepatitis C virus (HCV) infection, using transient elastography (TE) as the reference method. There was no significant difference between the feasibility rates of TE, ElastPQ and 2-D-SWE.GE (p = 0.507). A good correlation was found between the liver stiffness (LS) values obtained using the two elastographic methods (r = 0.78). The mean LS values obtained using the ElastPQ technique were significantly higher than those obtained using 2-D-SWE.GE (12.1 ± 7.3 kPa vs. 10.4 ± 4.0 kPa, p < 0.0001). Pairwise comparisons of receiver operator characteristics curves between 2-D-SWE.GE and ElastPQ have shown that there are no significant differences in their performance for staging F ≥ 2 fibrosis (p = 0.89), F ≥ 3 fibrosis (p = 0.76) and F = 4 fibrosis (p = 0.86) in patients with chronic HCV infection.

2D shear wave elastography combined with age and serum biomarkers prior to kasai surgery predicts native liver survival of biliary atresia infants

BACKGROUND

The prognosis of patients with biliary atresia (BA) after Kasai portoenterostomy (KPE) varies, and precisely predicting the outcomes of KPE before surgery is still challenging.

METHODS

A total of 158 patients who underwent KPE in our hospital were included in this study. The patients in the training cohort were recruited from January 2012 to October 2017 (n = 118), and then, those in the validation cohort were recruited from November 2017 to April 2019 (n = 40). Combined nomogram models were developed based on two-dimensional shear wave elastography (2D SWE) values and other biomarkers. The utility of the proposed models was evaluated by C-index.

RESULTS

2D SWE played a potentially important role in predicting native liver survival (NLS) of BA patients with a C-index of 0.69 (0.63 to 0.75) in the training cohort and 0.76 (0.67 to 0.85) in the validation cohort. The nomogram A based on 2D SWE values, age, gamma-glutamyl transferase (GGT) and aspartate aminotransferase-to-platelet ratio (APRI) had a better C-index in the training cohort [0.74 (0.68-0.80) vs. 0.66 (0.60-0.73), P = 0.017] and in the validation cohort [0.78 (0.70-0.86) vs. 0.60 (0.49-0.71), P = 0.002] than the nomogram B (without 2D SWE). Using risk score developed from nomogram A, we successfully predicted 88.0% (22/25) of patients in the training cohort and 75.0% (9/12) in the validation cohort to have survival time of less than 12 months after KPE.

CONCLUSION

The combined nomogram model based on 2D SWE values, age, GGT and APRI prior to KPE can effectively predict NLS in BA infants.