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

A Comprehensive Review of Liver Allograft Fibrosis and Steatosis: From Cause to Diagnosis

Despite advances in posttransplant care, long-term outcomes for liver transplant recipients remain unchanged. Approximately 25% of recipients will advance to graft cirrhosis and require retransplantation. Graft fibrosis progresses in the context of de novo or recurrent disease. Recurrent hepatitis C virus infection was previously the most important cause of graft failure but is now curable in the majority of patients. However, with an increasing prevalence of obesity and diabetes and nonalcoholic fatty liver disease as the most rapidly increasing indication for liver transplantation, metabolic dysfunction-associated liver injury is anticipated to become an important cause of graft fibrosis alongside alloimmune hepatitis and alcoholic liver disease. To better understand the landscape of the graft fibrosis literature, we summarize the associated epidemiology, cause, potential mechanisms, diagnosis, and complications. We additionally highlight the need for better noninvasive methods to ameliorate the management of graft fibrosis. Some examples include leveraging the microbiome, genetic, and machine learning methods to address these limitations. Overall, graft fibrosis is routinely seen by transplant clinicians, but it requires a better understanding of its underlying biology and contributors that can help inform diagnostic and therapeutic practices.

Comparison of Sound Touch Elastography, Sound Touch Quantify, and 4 Serum Fibrosis Indexes for the Diagnosis of Liver Fibrosis in Patients With Chronic Hepatitis B

ABSTRACT

The aim of this research was to compare the use of shear wave elastography (sound touch elastography [STE] and sound touch quantify [STQ]) and serum liver fibrosis indexes in the evaluation and staging of chronic hepatitis B (CHB) liver fibrosis. Sound touch elastography is a form of 2-dimensional shear wave elastography, and STQ is a form of point shear wave elastography. Between June 2018 and March 2019, 122 patients with CHB were assessed using STE and STQ. Serum liver biomarkers tests were undertaken, and liver biopsy was performed, and these were used to assign a pathological stage based on the Scheuer scoring system. A receiver operating characteristic curve was used to analyze the diagnostic value of noninvasive methods for evaluating and staging liver fibrosis. The cutoff values of STE for liver fibrosis stages S2 to S4 were 8.85, 9.97, and 10.29 kPa, respectively, and the areas under the receiver operating characteristic (AUCs) curve were 0.703, 0.821, and 0.900, respectively. The cutoff values of STQ for liver fibrosis stages S2 to S4 were 11.31, 13.81, and 20.60 kPa, respectively, and the AUCs were 0.674, 0.807, and 0.893, respectively. The AUCs of STE and STQ in diagnosing fibrosis stage were significantly higher than those of liver serum biomarkers (P < 0.05). The AUCs for the ability of the aspartate transaminase-to-platelet ratio index, the fibrosis index based on the 4 factors, the King score, and the Forns index to diagnose S2 fibrosis were 0.502, 0.624, 0.542, and 0.616, respectively, and the AUCs for their ability to diagnose S4 fibrosis were 0.856, 0.861, 0.883, and 0.823, respectively. Both STE and STQ are noninvasive methods for the assessment of liver fibrosis in CHB patients, with better diagnostic performances than those of 4 serum fibrosis indexes.

Noninvasive markers of liver steatosis and fibrosis after liver transplantation - Where do we stand?

In the last two decades, advances in immunosuppressive regimens have led to fewer complications of acute rejection crisis and consequently improved short-term graft and patient survival. In parallel with this great success, long-term post-transplantation complications have become a focus of interest of doctors engaged in transplant medicine. Metabolic syndrome (MetS) and its individual components, namely, obesity, dyslipidemia, diabetes, and hypertension, often develop in the post-transplant setting and are associated with immuno-suppressive therapy. Nonalcoholic fatty liver disease (NAFLD) is closely related to MetS and its individual components and is the liver manifestation of MetS. Therefore, it is not surprising that MetS and its individual components are associated with recurrent or "de novo" NAFLD after liver transplantation (LT). Fibrosis of the graft is one of the main determinants of overall morbidity and mortality in the post-LT period. In the assessment of post-LT steatosis and fibrosis, we have biochemical markers, imaging methods and liver biopsy. Because of the significant economic burden of post-LT steatosis and fibrosis and its potential consequences, there is an unmet need for noninvasive methods that are efficient and cost-effective. Biochemical scores can overestimate fibrosis and are not a good method for fibrosis evaluation in liver transplant recipients due to frequent post-LT thrombocytopenia. Transient elastography with controlled attenuation parameter is a promising noninvasive method for steatosis and fibrosis. In this review, we will specifically focus on the evaluation of steatosis and fibrosis in the post-LT setting in the context of de novo or recurrent NAFLD.

Elastography in the evaluation of liver allograft

Elastography is an established technique in the evaluation of chronic liver diseases. While there is a large clinical experience and data available regarding the performance of elastography in native liver, elastography experience with liver grafts is limited and still growing. Both ultrasound-based elastography techniques and MR Elastography (MRE) are useful in the assessment of liver fibrosis in liver transplants. Technical modifications for performing elastography will be required for optimum evaluation of the graft. In general, caution needs to be exercised regarding the use of elastography immediately following transplantation as post-operative changes, perioperative conditions/complications, inflammation, and rejection can cause increased stiffness in the graft. In the follow-up, detection of increased stiffness with elastography is useful for predicting development of fibrosis in the graft. Adjunctive MRI or ultrasound with Doppler also provides comprehensive evaluation of anatomy, vascular anastomosis and patency, biliary tree, and stiffness for fibrosis. In this review, we provide a brief overview of elastography techniques available followed by the literature review of elastography in the evaluation of grafts and illustration with clinical examples.

Study on the relationship between reduced scattering coefficient and Young's modulus of tumors in microwave ablation

BACKGROUND AND OBJECTIVE

In the clinical treatment of tumors using microwave ablation (MWA), although temperature can be used as an important reference index for evaluating the curative effect of ablation, it cannot fully reflect the biological activity status of tumor tissue during thermal ablation. Finding multi-parameter comprehensive evaluation factors to achieve real-time evaluation of therapeutic effects has become the key for precise ablation. More and more scholars use the reduced scattering coefficient (μs') and Young's modulus (E) to evaluate the treatment outcomes of MWA. However, the intrinsic relationship between these parameters is unclear. This paper aims to investigate the specific relationship between μs' and E during MWA.

MATERIAL AND METHODS

The MWA experiment was conducted on porcine liver in vitro, the two-parameter simultaneous acquisition system was designed to obtain the reduced scattering coefficient and Young's modulus of the liver tissue during MWA. The relationship between reduced scattering coefficient and Young's modulus was investigated.

RESULTS

It is found that the trend of change of μs' is very similar to E in the process of MWA, i.e. first increasing and then reaching a steady state, and in some experiments there are synchronous changes. Based on this, the quantitative relationship between E-μs'  is established, enabling the quantitative estimation of Young's modulus of liver tissue based on reduced scattering coefficient. The maximum absolute error is 29.37 kPa and the minimum absolute error is 0.88 kPa.

CONCLUSION

This study contributes to the further establishment of a multi-parameter MWA effectiveness evaluation model. It is also valuable for clinically evaluating the ablation outcomes of tumor in real time.

Liver Graft and Spleen Elastography After Living Liver Transplantation: Our First Results

AIM OF THE STUDY

Liver transplantation is widely applied as a standard and effective management of end-stage liver diseases, hepatocellular carcinoma, and acute liver failure. Investigation of morphologic and functional changes in the transplanted graft, gastrointestinal system, and spleen after transplantation is an important ground for assessment of post-transplantation results, early changes related to complications, and evaluation of response to treatment modalities. The aim of this study was to investigate the dynamics of changes in elastography of the liver graft and spleen after living-related liver transplantation.

MATERIAL AND METHODS

The study included 14 cirrhotic patients after living-related liver graft transplantation. Stiffness of the spleen and liver was evaluated before transplantation and at 1, 3, and 6 months after transplantation with a Supersonic Aixplorer Multi Wave device. Each procedure consisted of measuring the density in 10 points (spots) of the organ. The final result was calculated as the mean value of successful measurements (must have been > 60% of all measurements) and expressed in kilopascals.

RESULTS

The mean value of the liver and spleen stiffness before transplantation was 27 kPa (14-31 kPa) and 51 kPa (38-92 kPa), respectively. The stiffness of the spleen gradually reduced after transplantation to 40.3, 35.4, and 24.1 kPa (P = .001) at 1, 3, and 6 months. The stiffness of the liver graft in patients without complications was stable at 4-5 kPa, whereas the same value in patients with complications was increased (≥ 7.5 kPa). In 5 patients, endoscopic investigation confirmed the significant reduction of varicose veins after surgery.

CONCLUSION

Elastography of the liver graft and spleen after liver transplantation can be recommended as a useful-for-patient 1-off method of investigation.

Patchy echogenicity of the liver in patients with chronic hepatitis B does not indicate poorer elasticity

Purpose

This study was conducted to investigate whether the presence of patchy echogenicity in the liver of patients with chronic hepatitis B (CHB) is predictive of liver stiffness.

Methods

A total of 200 CHB patients with and without patchy echogenicity of the liver were assigned to two groups, with 100 patients in each group, and 32 of them underwent liver biopsy. Additionally, 80 healthy subjects, 100 inactive HBV carriers, and 100 patients with decompensated hepatic cirrhosis were assigned to the control groups. Laboratory tests and clinical data were collected, and shear wave velocity (SWV) of the liver was measured for all 480 subjects.

Results

The median SWV in patients with a normal liver, inactive hepatitis B virus carriers, CHB patients with and without patchy echogenicity, and decompensated hepatic cirrhosis were 1.07 m/sec, 1.08 m/sec, 1.16 m/sec, 1.16 m/sec, and 2.02 m/sec, respectively; there was no significant difference in SWV values between CHB patients with patchy echogenicity and those without patchy echogenicity. Furthermore, among CHB patients with and without patchy echogenicity, no significant difference in SWV was found according to fibrosis stage.

Conclusion

The presence of patchy echogenicity of the liver does not indicate a higher degree of liver stiffness.

Influence of Probe Pressure on Ultrasound-Based Shear Wave Elastography of the Liver Using Comb-Push 2-D Technology

It has been postulated that in the liver, applying increased probe pressure during ultrasound-based shear wave elastography (SWE) might lead to a false increase in the SWE result. We aimed to determine the influence of increased intercostal probe pressure when performing SWE of the liver. We also investigated the number of measurements required to achieve technically successful and reliable SWE examinations. This prospective, clinical study included 112 patients and 2240 SWE measurements of the liver. We applied probe pressure intercostally, to reduce the skin-to-liver capsule distance (SCD), which could stabilize the SWE signal and thus increase the number of technically successful measurements. We performed 10 measurements with maximum probe pressure and 10 with normal pressure in each patient. Thus, two analysis groups were compared for differences. Compared with normal pressure, maximum probe pressure significantly reduced the SCD (p < 0.001) and significantly increased the number of technically successful measurements from 981 to 1098, respectively (p < 0.001). The SWE results with normal and maximum probe pressure were 5.96 kPa (interquartile range: 2.41) and 5.45 kPa (interquartile range: 1.96), respectively (p < 0.001). In obese patients, a large SCD poses a diagnostic challenge for ultrasound SWE. We found that maximum intercostal probe pressure could reduce the SCD and increase the number of technically successful measurements, without falsely increasing the SWE result. Only three measurements were required to achieve technically successful and reliable SWE examinations.

The Application of Parametric Micro-Flow Imaging in the Evaluation of Liver Fibrosis

This study aims to investigate the application of parametric micro-flow imaging in the evaluation of liver fibrosis. From March 2013 to February 2014, 117 participants were recruited in this research prospectively, which includes 97 patients (who have been infected with hepatitis B virus or/and hepatitis C virus and have undergone liver biopsy) and 20 healthy volunteers. Contrast agent was injected as a bolus via the antecubital vein for the participants. Dynamic images of intercostal liver were collected and then divided into 30-second (30s) group and 10-second (10s) group. Color coding and quantitative analysis were performed, and related parameters were obtained and analyzed with the stage of liver fibrosis. The comparison of parameters between the stages of liver fibrosis was that the value of 30s slope reduced and the value of 10s slope increased with the increasing fibrosis stages. The value of 30s ratio at 5 seconds and 10s ratio at 5 seconds both increased with the increasing fibrosis stages. Receiver operating characteristic curves were obtained to evaluate the cutoff values and diagnosibility of parameters to predict F2 and higher or F3 and higher of fibrosis stages. The results show that parametric micro-flow imaging has potential value of guiding antiviral therapy for patients with viral hepatitis and evaluating the degree of improvement in liver fibrosis.