Normal liver stiffness: A study in living donors with normal liver histology

Vibration Controlled Transient Elastography in Screening for Silent Liver Diseases

OBJECTIVES

The objective of this study was to screen for significant hepatic fibrosis or steatosis in asymptomatic, apparently healthy subjects by using Vibration-controlled transient elastography and controlled attenuation parameter (CAP).

METHODS

Prospectively, 433 asymptomatic apparently healthy adults were included. Fibroscan/CAP examination was performed for all of them. Subjects with liver stiffness measurement > 6 kPa or CAP >248 dB/m were further evaluated to assess underlying chronic liver disease.

RESULTS

According to fibroscan/CAP examination, subjects were classified into four subgroups: normal (119) with CAP score of 215.85 ± 24.81 dB/m and fibrosis score of 4.47 ± 0.81 kPa, subjects with steatosis only 133 with CAP score of 309.41 ± 42.6 dB/m and fibrosis score of 4.74 ± 0.82 kPa, subjects with both steatosis and fibrosis 95 with CAP score of 318.20 ± 39.89 dB/m and fibrosis score of 7.92 ± 2.58 kPaand subjects with fibrosis only 86 with CAP score of 213.48 ± 22.62 dB/m and fibrosis score of 6.96 ± 1.11 kPa. S0 was present in 205 (47.3%), S1 in 48 (10.2%), S2 in 16 (3.7%) and S3 in 168 (38.8%) of studied subjects, whereas F0-1 was present in 371 (85.7%), F2 in 44 (10.16%), F3 in 16 (3.7%) subjects and F4 in only one (0.23%) subject. Subjects with both steatosis and fibrosis showed significantly higher transaminases, triglycerides and total cholesterol levels than other subgroups.

CONCLUSIONS

Most asymptomatic, apparently healthy subjects (72%) have significant steatosis and fibrosis. Liver stiffness measurement and CAP might represent promising first-line noninvasive procedures to screen for silent liver diseases in the general population.

A Case for Material Stiffness as a Design Parameter in Encapsulated Islet Transplantation

Diabetes is a disease that plagues over 463 million people globally. Approximately 40 million of these patients have type 1 diabetes mellitus (T1DM), and the global incidence is increasing by up to 5% per year. T1DM is where the body's immune system attacks the pancreas, specifically the pancreatic beta cells, with antibodies to prevent insulin production. Although current treatments such as exogenous insulin injections have been successful, exorbitant insulin costs and meticulous administration present the need for alternative long-term solutions to glucose dysregulation caused by diabetes. Encapsulated islet transplantation (EIT) is a tissue-engineered solution to diabetes. Donor islets are encapsulated in a semipermeable hydrogel, allowing the diffusion of oxygen, glucose, and insulin but preventing leukocyte infiltration and antibody access to the transplanted cells. Although successful in small animal models, EIT is still far from commercial use owing to necessary long-term systemic immunosuppressants and consistent immune rejection. Most published research has focused on tailoring the characteristics of the capsule material to promote clinical viability. However, most studies have been limited in scope to biochemical changes. Current mechanobiology studies on the effect of substrate stiffness on the function of leukocytes, especially macrophages-primary foreign body response (FBR) orchestrators, show promise in tailoring a favorable response to tissue-engineered therapies such as EIT. In this review, we explore strategies to improve the clinical viability of EIT. A brief overview of the immune system, the FBR, and current biochemical approaches will be elucidated throughout this exploration. Furthermore, an argument for using substrate stiffness as a capsule design parameter to increase EIT efficacy and clinical viability will be posed.

Liver transient elastography values in healthy South African children

BACKGROUND

Transient elastography (TE) is a rapid noninvasive ultrasound-based technology that measures liver stiffness as a surrogate for liver fibrosis and controlled attenuation parameter (CAP) as a measure of liver steatosis. However, normal ranges in children are not well defined in all populations. The aim of this study was to determine transient elastography values in healthy South African children.

METHODS

From April 2019 to December 2021, children were recruited from the HIV negative control group of a cohort study. Only children neither overweight nor obese, without evidence of liver disease, no medical condition or medication associated with hepatic steatosis or fibrosis and normal metabolic profile were included in this cross-sectional analysis. Clinical data, anthropometry and blood samples were collected on the same day as transient elastography with controlled attenuation parameter was performed.

RESULTS

104 children (median age 12.8 years [IQR 11.4-14.8, range 7.9-17.7 years]; 59 [57%] boys) were included. Liver stiffness was positively correlated with age (Pearson's r = 0.39, p < 0.001). Median liver stiffness in boys (5.2 kPa [5th to 95th percentiles 3.6 to 6.8 kPa]) was greater than in girls (4.6 kPa [5th to 95th percentiles 3.6 to 6.1 kPa; p = 0.004]), but there was no difference by ethnicity. Median CAP was 179dB/m (5th to 95th percentiles 158 to 233dB/m). There was a positive correlation between CAP and body mass index (BMI) z-score, but no difference by age, sex, ethnicity or pubertal status.

CONCLUSION

Liver stiffness values increase with age and are higher in healthy South African boys than girls, whereas CAP values vary with BMI, but not with age or sex.

Long-term hepatic safety of lomitapide in homozygous familial hypercholesterolaemia

INTRODUCTION

Lomitapide is a microsomal triglyceride transfer protein inhibitor for patients with homozygous familial hypercholesterolaemia. Due to its mechanism of action, potential hepatic effects of lomitapide are of clinical interest. This study aimed to determine the long-term hepatic safety of lomitapide.

METHODS

Data were aggregated from the pivotal phase 3 and extension phase clinical trial with lomitapide (median 5.1 years; serum total bilirubin, transaminases, cytokeratin-18 [CK-18] and enhanced liver fibrosis [ELF] score, fat-soluble vitamins and essential fatty acids), 8-year data from the Lomitapide Observational Worldwide Evaluation Registry (LOWER) and real-world evidence from a cohort of patients treated with lomitapide in Italy (hepatic elastography, and FIB-4 score for hepatic fibrosis).

RESULTS

In the phase 3 trial and the LOWER registry, any asymptomatic excursions in liver transaminase levels were not associated with elevations in bilirubin, and no Hy's law cases were detected in up to 8 years follow-up. There were no clinically relevant increases among hepatic biomarkers CK-18, CK-18 fragments or ELF score and fat-soluble vitamins and essential fatty acids remained above normal levels. In 34 patients treated in Italy with lomita pide for more than 9  years, elevations in hepatic fat were mild-to-moderate; hepatic stiffness remained normal, and the mean FIB-4 score remained below the fibrosis threshold value of 2.67.

CONCLUSIONS

These data indicate that the hepatic safety of lomitapide remains favourable with no clinically significant elevations in hepatic biomarkers and hepatic stiffness remained normal for more than 9 years follow-up. PHASE 3 TRIAL: NCT00730236; extension phase: NCT00943306; LOWER: NCT02135705.

Liver Stiffness Values in Persons with Normal Histology

Background and aims

Most studies to date have focused on liver stiffness measurement (LSM) in patients with different chronic liver diseases, and normal LSM is defined based on normal liver function tests or the absence of fibrosis. Very few studies have defined LSM based on completely normal liver biopsies. The current study was done to define the distribution of LSM values in individuals with normal liver biopsies.

Methods

All prospective liver donors presenting to Medanta, the Medicity hospital between September 2020 and September 2021 fulfilling the eligibility criteria were included in this study.

Results

A total of 63 donors (36 females and 27 males) were included in the study, 37 (58.7%) donors had normal liver biopsies, and 26 (41.2%) donors showed the presence of non-alcoholic fatty liver disease. LSM values in the normal liver histology group were 5.01 ± 1.99 kPa by the M probe and 5.34 ± 2.25 kPa by the XL probe. Even though the correlation was weak (r = 0.29, P = 0.03), M probe LSM correlated positively with body mass index. There was a good correlation between the LSM measured by the M probe and the XL probe (r = 0.73, P = <0.001).

Conclusions

LSM value in the biopsy-proven normal liver histology group was 5.01 ± 1.99 by the M probe and 5.34 ± 2.25 by the XL probe.

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

BACKGROUND AND AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Elastography and serum markers of fibrosis versus liver biopsy in 1270 Egyptian patients with hepatitis C

BACKGROUND

Chronic hepatitis C (CHC) is a leading cause of liver fibrosis.

OBJECTIVE

To compare utility of liver transient elastography, AST-to-platelet ratio index (APRI), fibrosis-4 index (FIB4), Forns Index and Goteborg University cirrhosis index (GUCI) in predicting fibrosis stage assessed by liver biopsy in Egyptian CHC patients.

METHODS

One thousand two-hundred and seventy CHC patients undergoing liver biopsy in preparation for therapy and 40 healthy potential living liver donors had transient elastography and calculation of APRI, FIB4, Forns and GUCI scores on the same day or day preceding the biopsy.

RESULTS

Mean age was 39.89 (17-60 years) and most were males (70.7%). All donors had F0 fibrosis, most patients had F1-F2 fibrosis (n = 1011, 79.6%) and 259 (20.4%) had F3-F4 fibrosis. Patients with F3-F4 fibrosis had higher median values of APRI (0.99 vs. 0.46), FIB4 (2.15 vs. 0.95) and Forns (7.34 vs. 4.79) indices, GUCI score (1.16 vs. 0.49) and transient elastography (19.2 vs. 6.2 kPa) (all P = 0.001). For F1 discrimination, AUROC of transient elastography was higher than both Forns and GUCI scores (P = 0.001). APRI, FIB4 and GUCI had lower AUROC than transient elastography for predicting fibrosis stage in F2 and F3 patients (P = 0.001). Transient elastography had the best area under receiver operating characteristic curve for predicting fibrosis stage in F4 patients (P = 0.001). The transient elastography cutoff values (kPa) were F1 (>4.8), F2 (>8.3), F3 (>10.1) and F4 (>13.4). Age, APRI, FIB4, Forns, GUCI and transient elastography were independent predictors of F3-F4 fibrosis.

CONCLUSION

Liver elastography is superior to APRI, FIB4, Forns and GUCI scores in predicting fibrosis in CHC patients.

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.

Range of Normal Liver Stiffness and Factors Associated With Increased Stiffness Measurements in Apparently Healthy Individuals

BACKGROUND & AIMS

Transient elastography (TE) is a noninvasive technique used to measure liver stiffness to estimate the severity of fibrosis. The range of liver stiffness measurements (LSMs) in healthy individuals is unclear. We performed a systematic review to determine the range of LSMs, examined by TE, in healthy individuals and individuals who are susceptible to fibrosis.

METHODS

We collected data from 16,082 individuals, in 26 cohorts, identified from systematic searches of Embase, Ovid MEDLINE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews for studies of liver stiffness measurements. Studies analyzed included apparently healthy adults (normal levels of liver enzymes, low-risk alcohol use patterns, and negative for markers of viral hepatitis). The presence of diabetes, hypertension, dyslipidemia, or steatosis, based on ultrasound examination, was known for most participants. We performed a meta-analysis of data from individual participants. The cohort was divided into 4 groups; participants with a body mass index <30 kg/m² were examined with the medium probe and those with a body mass index ≥30 kg/m² were examined with the extra-large probe. Linear regression models were conducted after adjusting for potential confounding factors of LSMs. We performed several sensitivity analyses.

RESULTS

We established LSM ranges for healthy individuals measured with both probes-these did not change significantly in sensitivity analyses of individuals with platelets ≥150,000/mm³ and levels of alanine aminotransferase ≤33 IU/L in men or ≤25 IU/L in women. In multivariate analysis, factors that modified LSMs with statistical significance included diabetes, dyslipidemia, waist circumference, level of aspartate aminotransferase, and systolic blood pressure at examination time. Significant increases in LSMs were associated with the metabolic syndrome in individuals examined by either probe. Diabetes in obese individuals increased the risk of LSMs in the range associated with advanced fibrosis.

CONCLUSIONS

In a systematic review and meta-analysis of data from individual participants, we established a comprehensive set of LSM ranges, measured by TE in large cohorts of healthy individuals and persons susceptible to hepatic fibrosis. Regression analyses identified factors associated with increased LSMs obtained by TE with the medium and extra-large probes.

Transient elastography in healthy subjects and factors influencing liver stiffness in non-alcoholic fatty liver disease: An Italian community-based population study

BACKGROUND

Few studies have been performed to explore parameters that influence liver stiffness measurement (LSM) using transient elastography in general population.

AIM

To explore factors influencing LSM in healthy and in subjects with non-alcoholic fatty liver disease (NAFLD).

METHODS

LSM was performed in a well-characterized cohort of subjects aged between 30 and 63 years. After exclusion of any causes of liver disease, the healthy cohort was defined and was compared with participants with NAFLD. The 95th percentile value of LSM in healthy was used as a cutoff suggesting relevant fibrosis.

RESULTS

Among 780 subjects evaluated, 331 were defined as healthy. The median value was 4.4kPa (3.7-5.2) and the 95th percentile was 6.8kPa. LSM was not influenced by gender, age, anthropometrics and biochemical parameters. Only insulin resistance was independently associated with increasing of LSM. In the cohort of 157 subjects with NAFLD, LSM was higher than in healthy (5.6±1.9 vs 4.6±1.3kPa; p<0.001). On multivariate analysis, the degree of steatosis was independently associated with increasing of LSM in NAFLD cohort (β=0.271; 95% CI=0.026-0.095; p<0.001). Participants with diabetes and/or severe steatosis had the highest probabilities of relevant fibrosis.

CONCLUSIONS

LSM varies between 3.7 and 5.2kPa in healthy Caucasians and is influenced only by insulin resistance. In NAFLD, severe steatosis and diabetes are factors influencing LSM.

Normal and Fibrotic Rat Livers Demonstrate Shear Strain Softening and Compression Stiffening: A Model for Soft Tissue Mechanics

Tissues including liver stiffen and acquire more extracellular matrix with fibrosis. The relationship between matrix content and stiffness, however, is non-linear, and stiffness is only one component of tissue mechanics. The mechanical response of tissues such as liver to physiological stresses is not well described, and models of tissue mechanics are limited. To better understand the mechanics of the normal and fibrotic rat liver, we carried out a series of studies using parallel plate rheometry, measuring the response to compressive, extensional, and shear strains. We found that the shear storage and loss moduli G’ and G” and the apparent Young's moduli measured by uniaxial strain orthogonal to the shear direction increased markedly with both progressive fibrosis and increasing compression, that livers shear strain softened, and that significant increases in shear modulus with compressional stress occurred within a range consistent with increased sinusoidal pressures in liver disease. Proteoglycan content and integrin-matrix interactions were significant determinants of liver mechanics, particularly in compression. We propose a new non-linear constitutive model of the liver. A key feature of this model is that, while it assumes overall liver incompressibility, it takes into account water flow and solid phase compressibility. In sum, we report a detailed study of non-linear liver mechanics under physiological strains in the normal state, early fibrosis, and late fibrosis. We propose a constitutive model that captures compression stiffening, tension softening, and shear softening, and can be understood in terms of the cellular and matrix components of the liver.