Acoustic radiation force impulse imaging for detection of liver fibrosis in overweight and obese children

Noninvasive biomarkers in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide among children and adolescents. It encompasses a spectrum of disease, from its mildest form of isolated steatosis, to nonalcoholic steatohepatitis (NASH) to liver fibrosis and cirrhosis, or end-stage liver disease. The early diagnosis of pediatric NAFLD is crucial in preventing disease progression and in improving outcomes. Currently, liver biopsy is the gold standard for diagnosing NAFLD. However, given its invasive nature, there has been significant interest in developing noninvasive methods that can be used as accurate alternatives. Here, we review noninvasive biomarkers in pediatric NAFLD, focusing primarily on the diagnostic accuracy of various biomarkers as measured by their area under the receiver operating characteristic, sensitivity, and specificity. We examine two major approaches to noninvasive biomarkers in children with NAFLD. First, the biological approach that quantifies serological biomarkers. This includes the study of individual circulating molecules as biomarkers as well as the use of composite algorithms derived from combinations of biomarkers. The second is a more physical approach that examines data measured through imaging techniques as noninvasive biomarkers for pediatric NAFLD. Each of these approaches was applied to children with NAFLD, NASH, and NAFLD with fibrosis. Finally, we suggest possible areas for future research based on current gaps in knowledge.

Clinical and diagnostic characteristics of non-alcoholic fatty liver disease among Egyptian children and adolescents with type1 diabetes

BACKGROUND

Type 1 diabetes mellitus (T1DM) patients are at an increased risk for non-alcoholic fatty liver disease (NAFLD). This study aimed to evaluate the clinical criteria associated with the diagnosis of Non-Alcoholic Fatty Liver Disease (NAFLD) among T1DM Egyptian children and adolescents.

METHODS

74 T1DM patients aged 8-18 year were enrolled in this cross sectional study. Assessments of Clinical status, anthropometric measures, lipid profile, glycated haemoglobin (HbA1c) and liver enzymes were done. Abdominal Ultrasound evaluation of hepatic steatosis was done. Accordingly, patients were divided into two groups (NAFLD and normal liver group) and compared together. Assessment of liver fibrosis using acoustic radiation force impulse elastography (ARFI) was done. Statistical analysis included; independent t-test, Chi square and Fisher's Exact, Pearson and Spearman tests and Logistic regression models for factors associated with fatty liver were used when appropriate.

RESULTS

In this study; 74 patients were enrolled; 37 males (50%) and 37 females with mean age 14.3 ± 3.0 year. The mean insulin dose was 1.1 ± 0.4 U/kg and mean disease duration was 6.3 ± 3.0 year. NAFLD was detected in 46 cases while 28 cases had normal liver as diagnosed by abdominal ultrasound. Cases with NAFLD had statistically significant higher BMI-Z scores, waist/hip, waist/height and sum of skin fold thicknesses compared to those with normal liver (P < 0.05). The mean value of HbA1c % was significantly higher in NAFLD group (P = 0.003). Total cholesterol, triglycerides and LDL serum levels were significantly elevated (p < 0.05), while the HDL level was significantly lower in NAFLD cases (p = 0.001). Although, serum levels of liver enzymes; ALT and AST were significantly higher among cases with NAFLD than in normal liver group (p < 0.05), their means were within normal. Using the ARFI elastography; NAFLD cases exhibited significant fibrosis (F2, 3 and 4). BMI, patient age and female gender were among risk factors for NAFLD.

CONCLUSIONS

NAFLD represents a serious consequence in type 1 diabetic children and adolescents that deserves attention especially with poor glycemic control. NAFLD has the potential to evolve to fibrosis. This study demonstrated a very high prevalence of NAFLD in T1D children and adolescents using US which was (62.2%) with the percent of liver fibrosis among the NAFLD cases (F2-F4) using ARFI elastography was 26%. BMI, age of patients and female gender were detected as risk factors for NAFLD.

Do deep inspiration breath-holds and free-breathing affect pancreatic tissue stiffness in shear wave elastography?

PURPOSE

The use of ultrasound (US) elastography to assess the pancreas is subject to serious limitations, and it is not easy to perform US elastography for the pancreas with satisfactory and reproducible accuracy. The aim of our study was to show the normal pancreatic stiffness values with shear wave elastography (SWE) and to evaluate the pancreatic tissue stiffness at two different respiratory phases.

METHODS

Sixty-three subjects were included in the study. Median values of pancreatic stiffness were recorded. Values during deep inspiration and free breathing were compared.

RESULTS

The stiffness values of the pancreatic tissue measured during deep inspiration breath holds and during free breathing were 5.70 ± 1.74 kPa and 4.15 ± 1.70 kPa, respectively. It was found that the values of pancreatic tissue stiffness measured during deep inspiration were statistically significantly higher than those measured during physiological breathing (p < 0.001).

CONCLUSIONS

Because of the reference value differences between different ultrasound elastography devices, it is important to know the reference ranges of normal pancreatic stiffness according to the device, in order to distinguish possible pathologies. In addition, the variability of pancreatic stiffness measurements with respiratory phases should be considered in clinical applications.

Diagnosis and Staging of Pediatric Non-Alcoholic Fatty Liver Disease: Is Classical Ultrasound the Answer?

The increased prevalence of non-alcoholic fatty liver disease (NAFLD) requires special attention in pediatric patients, as it manifests in them in a more severe and progressive way compared to adults. The implementation of the appropriate therapeutic interventions is determinant of the attempts to treat it. For that purpose, early diagnosis and staging of the disease is essential. The purpose of this review was to find and reveal the most appropriate diagnostic strategies and tools for diagnosis and staging of pediatric NAFLD/NASH based on their accuracy, safety and effectiveness. The methodology followed was that of the literature review. Particular emphasis was put on the recent bibliography. A comparative study of published articles about the diagnosis and management of pediatric NAFLD/NASH was also performed. In terms of diagnosis, the findings converged on the use of classical ultrasound. Ultrasound presented average sensitivity and specificity for diagnosing the disease in children, while in the adult population, sensitivity and specificity were significantly higher. Proton density fat fraction magnetic resonance imaging has been increasingly used for the diagnosis of steatosis in pediatric patients. Elastography is an effective tool for staging liver fibrosis and discriminating NASH from NAFLD in children. Even though liver biopsy is the gold standard, especially for NASH, it should be avoided for pediatric patients. Biochemical tests are less specific and less sensitive for the diagnosis of NAFLD, and some of them are of high cost. It seems that diagnostic imaging should be a first-line tool for the staging and monitoring pediatric NAFLD/NASH in order for appropriate interventions to be implanted in a timely way.

Noninvasive diagnostic tools for pediatric NAFLD: where are we now?

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is a leading cause of liver disease in the pediatric population. It is a significant liver complication of obesity that also prominently affects children. Over the past decade, several noninvasive methods have been investigated for replacing liver biopsy to identify which children with NAFLD have nonalcoholic steatohepatitis (NASH) and fibrosis. These methods that aim to differentiate the type and extent of liver damage are based on two main different methodologies: a 'biological' approach centered on the quantification of circulating biomarkers; and a 'physical' approach established by analyzing different imaging data.

AREAS COVERED

In this review, we illustrate the state of the art and recent discoveries on noninvasive methods for the diagnosis of NAFLD, NASH, and advanced fibrosis.

EXPERT OPINION

Currently, noninvasive tests cannot diagnose NASH or determine the degree of fibrosis. However, several lines of evidence have suggested that if these tests are used in a complementary way with other laboratory tests and imaging they have the potential to be used to monitor progression of disease and response to therapy in pediatric NAFLD. Future scientific research will focus on combining these methods with multiple potential predictors of genetic susceptibility.

Diagnosis of Acute Rejection of Liver Grafts in Young Children Using Acoustic Radiation Force Impulse Imaging

OBJECTIVE. Frequency of acute rejection (AR) after pediatric liver transplant remains high despite progress in immunosuppression. Liver biopsy (LB) is the reference standard for the diagnosis of AR despite its potential for morbidity. The purpose of our study was to evaluate the ability of acoustic radiation force impulse (ARFI) imaging to distinguish AR from other causes of short- and medium-term liver dysfunction and to identify liver transplant cases with normal liver function. MATERIALS AND METHODS. ARFI imaging was used to evaluate shear wave velocity (SWV) after liver transplant in young children. All pediatric liver grafts that had LB and ARFI examination between January 2014 and December 2017 were included in this retrospective study. Results of LB were compared with those of SWV. Collected data included age at biopsy and transplant, sex, weight, height, body mass index, interval between liver transplant and shear wave elastography and LB, kind of graft, type of donor, and diagnosis at transplant. ROC curve analysis was performed to assess the diagnostic performance of SWV. Optimal cutoff of SWV using ARFI imaging in predicting AR was identified using the Youden index. RESULTS. Statistical analysis was performed on 54 children; six of the original 60 were excluded because of confounding alterations or changes in outcome. Median SWV was higher in patients with AR (2.03 m/s; interquartile range [IQR], 1.80-2.45 m/s) compared with those with idiopathic hepatitis (1.33 m/s; IQR, 1.12-1.53 m/s), portal hypertension (1.42 m/s; IQR, 1.32-1.72 m/s), cholangitis (1.56 m/s; IQR, 1.07-1.62 m/s) or normal liver function (1.23 m/s; IQR 1.12-1.29 m/s) at protocol biopsies (all comparisons, p < 0.01). SWV higher than 1.73 m/s was predictive for AR (AUC, 0.966). SWV also showed good diagnostic accuracy in normal liver function (AUC, 0.791). ARFI imaging was not predictive for hepatitis (AUC, 0.402), portal hypertension (AUC, 0.556), or cholangitis (AUC, 0.420). CONCLUSION. ARFI imaging could be routinely used in place of LB in pediatric patients with liver dysfunction after liver transplant, restricting indication and risks of biopsy to selected cases.

Childhood and Adolescent Nonalcoholic Fatty Liver Disease: Is It Different from Adults?

Paediatric nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in childhood and adolescence. Although the condition is similar in many ways to NAFLD in adults, there are important differences in predisposition, presentation, differential diagnosis and potentially also in optimal management. Antenatal and early childhood exposures and the particular vulnerabilities to environmental influences in a growing child, present unique opportunities for intervention and modification of risk. The prevalence of significant fibrosis on biopsy in preadolescent children in the context of NAFLD should not be ignored, but the relevance of this fibrosis to long-term outcome is as yet unknown. The approach to children and adolescents with suspected NAFLD needs to include an assessment of risk factors in addition to exclusion of alternative or coexisting liver diseases. Liver biopsy is indicated for younger children and for those without clear predisposing factors leading to metabolic syndrome, also for those in whom significant fibrosis is suspected. The histology in children and adolescents differs from adults in whom type 2 NAFLD may be more prevalent, which is associated in turn with more significant fibrosis. Management in children and adolescents needs to focus on lifestyle intervention, which when weight loss is achieved, demonstrates excellent results in terms of resolution of disease. Appropriate intervention in childhood and adolescence may prove instrumental in avoiding the need for later transplantation while also decreasing all-cause mortality in these at-risk individuals.

Methods to improve the noninvasive diagnosis and assessment of disease severity in children with suspected nonalcoholic fatty liver disease (NAFLD): Study design

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with obesity and is the most common liver disease in the developed world. In children with suspected NAFLD, present guidelines suggest consideration of alternative diagnoses via extensive blood testing, though the yield of this work up is unknown. Furthermore, the gold standard diagnostic test for NAFLD remains liver biopsy, making the development of non-invasive tests critically important.

OBJECTIVES

Our objectives are: 1) to determine the accuracy of elastography and multiple serum biomarkers - each assessed individually and as algorithms (including those previously tested in adults) - for the diagnosis of nonalcoholic steatohepatitis (NASH) and early fibrosis in children and (2) to examine the utility of extensive testing for rare alternative diagnoses in overweight or obese children with elevated alanine aminotransferase (ALT) suspected to have NAFLD.

DESIGN

This is an ongoing, cross-sectional study in children 2-18 years of age with up to 2 years of prospective follow up. Eligible patients are asymptomatic, overweight or obese, and have an ALT ≥35 U/L upon enrollment. Two forms of elastography are obtained serially along with anthropometric data and routine laboratory tests. Elastography and serum biomarkers are also performed immediately prior to any clinically-indicated biopsy.

METHODS

Between April 2015 and April 2018, 193 children have been enrolled in this ongoing study and 71 have undergone liver biopsy. Here we carefully report the rationale, methodology, and preliminary data for this study.