Liver Stiffness Measured by Shear-wave Elastography for Evaluating Intrahepatic Portal Hypertension in Children

Budd-Chiari syndrome in children: Radiological intervention and role of shear wave elastography in monitoring response

OBJECTIVES

Radiological intervention (RI) is the preferred treatment in children with Budd-Chiari syndrome (BCS). We studied the comparative long-term outcome of BCS children, with and without RI and utility of liver and splenic stiffness measurement (LSM, SSM) by 2-dimensional shear wave elastography (2D-SWE) in assessing response.

METHODS

Sixty children (40 boys, median age 10.5 [6.5-15.25] years) with BCS (29 newly diagnosed, 31 follow-up) were evaluated. LSM and SSM by 2D-SWE and vascular patency were monitored pre- and postprocedure (≥ 6 months postprocedure) in those undergoing RI. Medical therapy without anticoagulation and monitoring was done in subjects without RI. The RI and no-RI groups were compared.

RESULTS

Ascites (54,90%), hepatomegaly (56,93%) and prominent abdominal-veins (42,70%), were the commonest features. The majority (46,78%) had isolated hepatic vein block. 44 (73%) cases underwent RI, while 16 (27%) were managed conservatively. Both groups were similar at baseline. Post-RI subjects showed significant improvement in clinical findings, liver functions and portal hypertension. LSM [33 (32-34.5) to 19.2 (18-20.67) kPa] and SSM [54.5 (52.3-57.6) to 28.9 (27.6-30.25) kPa] showed a significant decline from baseline value over a follow-up of 12 (6-13) months. Gradual reduction occurred in the LSM and SSM over 1-5 years, with near-normal LSM [10.2 (9.2-11.5) kPa] and SSM [22.3 (20.5-24.3) kPa] values in patients (n-16) with > 5 years follow-up. Patients without RI showed worsening in LSM and SSM. Hepatopulmonary syndrome and hepatocellular carcinoma developed in 4 (8%) and 1 (1.7%) cases respectively.

CONCLUSION

RI leads to clinical recovery and reduction with near normalization of LSM and SSM over long-term follow-up in children with BCS. 2D-SWE is a promising tool to monitor outcomes.

Budd-Chiari syndrome in children: Challenges and outcome

Budd-Chiari syndrome (BCS) is an uncommon disease of the liver, characterised by obstruction of the hepatic venous outflow tract. The etiological spectrum of BCS as well as venous obstruction pattern show wide geographical and demographic variations across the globe. Compared to adults with BCS, children have primary BCS as the predominant etiology, earlier clinical presentation, and hence better treatment outcome. Underlying prothrombotic conditions play a key role in the etiopathogenesis of BCS, though work-up for the same is often unyielding in children. Use of next-generation sequencing in addition to conventional tests for thrombophilia leads to better diagnostic yield. In recent years, advances in radiological endovascular intervention techniques have revolutionized the treatment and outcome of BCS. Various non-invasive markers of fibrosis like liver and splenic stiffness measurement are being increasingly used to assess treatment response. Elastography techniques provide a novel non-invasive tool for measuring liver and splenic stiffness. This article reviews the diagnostic and therapeutic advances and challenges in children with BCS.

Beyond Varices: Complications of Cirrhotic Portal Hypertension in Pediatrics

Complications of cirrhotic portal hypertension (PHTN) in children are broad and include clinical manifestations ranging from variceal hemorrhage, hepatic encephalopathy (HE), ascites, spontaneous bacterial peritonitis (SBP), and hepatorenal syndrome (HRS) to less common conditions such as hepatopulmonary syndrome, portopulmonary hypertension, and cirrhotic cardiomyopathy. The approaches to the diagnosis and management of these complications have become standard of practice in adults with cirrhosis with many guidance statements available. However, there is limited literature on the diagnosis and management of these complications of PHTN in children with much of the current guidance available focused on variceal hemorrhage. The aim of this review is to summarize the current literature in adults who experience these complications of cirrhotic PHTN beyond variceal hemorrhage and present the available literature in children, with a focus on diagnosis, management, and liver transplant decision making in children with cirrhosis who develop ascites, SBP, HRS, HE, and cardiopulmonary complications.

Network Meta-Analysis: Noninvasive Imaging Modalities for Identifying Clinically Significant Portal Hypertension

BACKGROUND

Although measurement of the hepatic venous pressure gradient (HVPG) is the current reference standard for obtaining portal venous pressures, several noninvasive imaging-based modalities have been proposed as alternatives.

AIMS

We performed a systematic review and meta-analysis to compare the diagnostic accuracy of noninvasive imaging approaches for identifying clinically significant portal hypertension (CSPH).

METHODS

Two independent reviewers conducted a literature search of PubMed, SCOPUS, and the Cochrane Library from inception until January 5, 2021. The following imaging modalities were compared to HVPG: computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance elastography, ultrasound, transient elastography (TE), shear wave elastography (SWE), acoustic radiation force impulse (ARFI) imaging, contrast-enhanced ultrasound (CEUS), and subharmonic-aided pressure estimation (SHAPE). Sensitivity, specificity, diagnostic odds ratio (DOR), and area under the curve (AUC) for summary receiver operating characteristic were calculated using both frequentist random effects and Bayesian network meta-analytic approaches.

RESULTS

We analyzed 45 studies of 5678 patients. A broad overlapping confidence interval (CI) of DOR was observed among different imaging modalities: ARFI (30.5; 95% CI 12.7-73.3), CEUS and SHAPE (21.1; 95% CI 6.4-69.8), TE of liver stiffness (21.1; 95% CI 13.3-33.5), CT and MRI (13.7; 95% CI 7.40-25.4), SWE of liver stiffness (10.5; 95% CI 5.2-21.1), and ultrasound (9.5; 95% CI 4.9-18.4). The AUC of all imaging methods exceeded 0.8, indicating very good performance. At a cutoff of 80% specificity, TE, CEUS, and SHAPE exceeded 80% sensitivity.

CONCLUSION

Overall, noninvasive imaging modalities perform well for identifying CSPH. Clinicians should consider these noninvasive and cost-efficient tests when diagnosing CSPH.

Ultrasound Shear Wave Elastography of the Intervertebral Disc and Idiopathic Scoliosis: A Systematic Review

Ultrasound shear wave elastography is a radiation-free and low-cost technique for evaluating the mechanical properties of different tissues. This study systematically reviewed all relevant literature on shear wave elastography of the intervertebral disc. The purpose was twofold: first, to determine the validity of the elastography method, that is, the correlation between elastographically measured shear wave speed and disc mechanical properties, and inter-/intra-operator reliability; and second, to explore if disc elastography is potentially useful in identifying children at risk for idiopathic scoliosis. This systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. A comprehensive search was performed in PubMed and Embase, and study quality was assessed using the AXIS (Appraisal Tool for Cross-sectional Studies) critical appraisal instrument. Seven articles were included. Three animal ex vivo studies reported moderate-to-good correlations between shear wave speed and disc mechanical properties (r = 0.45-0.81). Three studies reported high intra-operator repeatability (intra-class correlation coefficient [ICC] 0.94-0.99) and inter-operator reproducibility (ICC 0.97-0.98). Four clinical studies measured shear wave speed in asymptomatic children. Two studies reported significantly higher shear wave speeds in scoliosis patients compared with healthy controls, measured in discs both inside and outside the scoliotic curve. In conclusion, shear wave elastography appears reliable in assessing intervertebral disc mechanical characteristics. Despite its promising capabilities to distinguish patients with asymptomatic from those with pathological discs, the exact correlation between disc mechanical properties and shear wave speed remains unclear.

Liver stiffness assessed by real-time two-dimensional shear wave elastography predicts hypersplenism in patients with Wilson's disease: a prospective study

Background

The current study aimed to explore the value of liver stiffness assessed by two-dimensional real-time shear wave elastography (2D-SWE) to predict hypersplenism occurrence in Wilson’s disease (WD) patients.

Methods

Ninety WD patients were enrolled in this prospective study between May 2018 and December 2018. Baseline clinical data and ultrasound imaging including 2D-SWE liver stiffness of WD patients were collected. After enrollment, patients had follow-ups for 24 months or until they developed hypersplenism. The hypersplenism risk factors were determined using Cox regressions and receiver operating characteristic curves (ROC).

Results

Twenty-nine (32.2%) patients developed hypersplenism. Age, portal vein diameter, and liver stiffness were independent hypersplenism risk factors in WD patients. The cutoff value of liver stiffness to predict hypersplenism was 10.45 kPa, with sensitivity and specificity of 75.9% and 73.8%, respectively. Patients were divided into two groups according to liver stiffness: ≥ 10.45 kPa (57.9% with hypersplenism) or < 10.45 kPa (13.5% with hypersplenism). The median time between enrollment and hypersplenism development was 15 months vs. 22 months (p < 0.001) for the two groups, respectively.

Conclusion

The measurement of liver stiffness by 2D-SWE can be a reliable hypersplenism predictor in WD patients. Therefore, dynamic monitoring of WD patients using 2D-SWE is crucial for the early diagnosis of hypersplenism.

Elastography for Pediatric Chronic Liver Disease: A Review and Expert Opinion

In adults with chronic liver diseases, ultrasound and magnetic resonance shear wave elastography (SWE) can replace liver biopsy in several clinical scenarios. Several guidelines on the use of ultrasound SWE for the adult population have been published. However, the number of publications in the pediatric population is limited, and available guidelines on SWE do not specifically address pediatric chronic liver diseases. In this article, we review the literature on the use of SWE for pediatric chronic liver diseases and provide expert opinion on how to use SWE, both ultrasound and magnetic resonance techniques, in the pediatric population.

Biomechanical Evaluation of Intercostal Muscles in Healthy Children and Adolescent Idiopathic Scoliosis: A Preliminary Study

Spine deformity during adolescent idiopathic scoliosis can induce a rib-cage deformity. This bone deformity can have direct consequences on the chest-wall muscles, including intercostal muscles, leading to respiratory impairments in individuals with severe cases. The aim of this study was to determine whether shear-wave elastography can be used to measure intercostal-muscle shear-wave speed (SWS) in healthy children and those with adolescent idiopathic scoliosis (AIS). Nineteen healthy participants and 16 with AIS took part. SWS measurements were taken by three operators, twice each. Average SWS was 2.3 ± 0.4 m/s, and inter-operator reproducibility was 0.2 m/s. SWS was significantly higher during apnea than in normal breathing (p < 0.01) in both groups. No significant difference was observed between groups in apnea or in normal breathing. Characterization of the intercostal muscles by ultrasound elastography is therefore feasible and reliable for children and adolescents with and without scoliosis.

Validating the BAVENO VI criteria to identify low risk biliary atresia patients without endoscopy for esophageal varix

BACKGROUND AND AIMS

Portoenterostomy is the initial surgical treatment for biliary atresia (BA); however, no curative therapy exists for BA. Varix bleeding is a major complication of end-stage liver disease and must be determined in patients with BA, necessitating routine surveillance using esophagogastroduodenoscopy (EGD). We attempted to validate criteria to identify BA patients requiring EGD.

METHODS

From January 2007 to December 2017, we selected BA patients who underwent Kasai surgery, transient elastography (TE), and EGD at Severance hospital. In total, 190 cases were included; laboratory tests and EGDs were carried out from 3 months before TE to 3 months after TE.

RESULTS

Based on the cut-off value (<10) of the liver stiffness measurement (LSM), 35 (81.4%) patients with low-risk varix (LRV) and 8 (18.6%) with high-risk varix (HRV) were identified. Based on platelet counts (>150,000), 87 (77.68%) patients with LRV and 25 (22.32%) with HRV were identified. Based on this, the BAVENO VI criteria, which identify patients who can safely avoid screening EGD, missed 9/68 (13.24%) of HRV patients. The expanded BAVENO VI criteria missed 21/68 (30.88%) of HRV patients. However, the criteria using LSM <10 and platelet count >150,000 missed identifying only 4/68 (5.88%) HRV patients.

CONCLUSIONS

The BAVENO criteria may be as useful in children with BA as in adults with liver cirrhosis. Regular laboratory tests, imaging studies, and EGD may avoid missing diagnoses of varices in BA patients. However, LSM<10 and platelet count>150,000 may provide more accurate criteria and help identify patients who does not need endoscopy.

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.

Diagnostic Performance of Ultrasound Elastography and Serologic Fibrosis Indices for Evaluation of Hepatic Involvement in Wilson Disease

OBJECTIVES

To investigate the diagnostic value of transient elastography (TE), 2-dimensional (2D) shear wave elastography (SWE), and the serologic fibrosis indices aspartate transaminase-to-platelet ratio index (APRI) and Fibrosis-4 (FIB-4) score for Wilson disease (WD).

METHODS

We retrospectively identified patients with a diagnosis of WD who underwent TE and 2D SWE on the same day. Their APRI and FIB-4 scores were calculated. Hepatic involvement was classified into 5 clinical categories (I-V) based on the laboratory findings, hepatic morphologic characteristics on ultrasound (US) imaging, and clinical symptoms of cirrhosis: I, normal (n = 17); II, only biochemical abnormality (n = 15); III, altered hepatic morphologic characteristics (n = 10); IV, compensated liver cirrhosis (n = 3); and V, decompensated liver cirrhosis (n = 0). We compared the area under the receiver operating characteristic curve (AUROC) data for TE, 2D SWE, the APRI, and the FIB-4 score. A combined assessment of the serologic markers and US elastography was performed, and the AUROCs of the combinations were compared.

RESULTS

Forty-five patients were included in the study (median age, 16.0 years; range, 3-35 years). Transient elastography, 2D SWE, and APRI were comparable in distinguishing the clinical categories (AUROC, 0.799-0.928). The FIB-4 score showed lower diagnostic value in distinguishing clinical category I from the other categories (AUROC, 0.647). Combining the serologic markers and US elastography significantly increased the AUROC value of the FIB-4 score (with TE and 2D SWE, P = .01 and .02).

CONCLUSIONS

Transient elastography and 2D SWE showed excellent diagnostic accuracy for differentiating the clinical categories of hepatic involvement. The APRI showed better diagnostic performance than the FIB-4 score. The assessment of hepatic manifestations in WD can be improved by combining US elastography with serologic indices.

Cystic Fibrosis-related Liver Disease: The Next Challenge

Up to 40% of individuals with cystic fibrosis have cystic fibrosis-related liver disease (CFLD); however, only 5% to 10% will have clinically evident disease. With the introduction of powerful cystic fibrosis transmembrane conductance regulator (CFTR) enhancers, effective treatment for cystic fibrosis is available. The role of CFTR enhancers in liver disease is unknown at this time. The traditionally accepted theory of the pathogenesis of CFLD is being questioned. A different pathogenesis may lead to new ways to treat CFLD. The way that CFLD is diagnosed and monitored is evolving as new imaging technology become available.

Comparison of 2-Dimensional Shear Wave Elastographic Measurements Using ElastQ Imaging and SuperSonic Shear Imaging: Phantom Study and Clinical Pilot Study

OBJECTIVES

To compare the feasibility and clinical applicability of ElastQ imaging (Philips Healthcare, Best, the Netherlands) with that of SuperSonic shear imaging (SSI; SuperSonic Imagine, Aix-en-Provence, France) using an elastographic phantom and a pilot study of patients.

METHODS

Two-dimensional shear wave elastography measurement was performed by ElastQ imaging and SSI by 2 radiologists. An elastographic phantom with 5 target elasticities at 2 acquisition depths was used. The coefficients of variation and intraclass correlation coefficients (ICCs) were evaluated for repeatability and interobserver agreement, respectively. The mean elasticities of the systems at each target were compared. The proportions of measurements that were out of the range of expected values and measurement errors were calculated to determine accuracy. Liver stiffness (LS) was measured by both systems in 27 children and young adult patients with various liver diseases.

RESULTS

Both systems provided high repeatability in elasticity measurements of phantom targets (coefficients of variation, 0.69%-15.82%), and there was excellent interobserver agreement (ICC, 0.992). Most (90%) mean elasticities of targets were significantly different between the techniques (P ≤ .002) and acquisition depths (P ≤ .004). ElastQ imaging had significantly lower proportions of out-of-range measurements and measurement errors (P ≤ .003) than SSI. In patients with liver disease, LS measurements of the systems were strongly correlated (ρ = 0.955; P < .001) and had excellent agreement (ICC, 0.951; P < .001).

CONCLUSIONS

ElastQ imaging had comparably good results in terms of repeatability, interobserver agreement, and accuracy in the phantom model compared with SSI. The pilot patient study showed strong correlations in LS values between the systems.

Spleen and Liver Stiffness to Detect Esophageal Varices in Children with Biliary Atresia

OBJECTIVES

The aim of the study was to determine the accuracy of noninvasive parameters, such as liver (LS) and spleen stiffness (SS) to detect esophageal varices (EV) in children with biliary atresia (BA).

METHODS

Children with BA between 2000 and 2015 were recruited. All underwent esophagogastroduodenoscopy and transient elastography. Demographic data, laboratory investigations, alanine transferase-to-platelet ratio index (APRI), and Varices Prediction Rule (VPR) score were collected.

RESULTS

A total of 51 children (mean age 10.63 years, standard deviation (SD) = 6.08 years; 53% boys) were enrolled. There were differences in onset and outcome of portoenterostomy, spleen palpablility, platelet count, albumin, LS, SS, and VPR between the varice and varice-free groups (P < 0.05). In the varice group, the median LS was 18.12 (interquartile ratio, IQR 13.15-19.12) and the median SS was 46.85 (IQR 25.95-54.55) kPa. In the varice-free group, the median LS was 7.85 (IQR 5.88-16.75) and the median SS was 16.54 (IQR 11.75-21.75) kPa. Both LS and SS were higher in the varice than the varice-free group (P < 0001). The area under the receiver operating characteristic curve of LS, SS, spleen palpability, platelet count, APRI, and VPR were 0.734, 0.870, 0.817, 0.810, 0.751, and 0.794, respectively. Using a cut-off value of 12.5 kPa for LS, the sensitivity and specificity were 80 and 70%, respectively. Using a cut-off value of 28.9 kPa for SS, the sensitivity and specificity were 75 and 87%, respectively. Combination of LS and SS to diagnose varices increased the specificity to 93%.

CONCLUSIONS

SS as a single marker had the best diagnostic value to predict esophageal varices in children with BA. The combination of SS and LS furthermore, increased the diagnostic yield.

Diagnostic Performance of Ultrasound Elastography for Evaluating Portal Hypertension in Children: A Systematic Review and Meta-analysis

OBJECTIVES

To assess the diagnostic performance of ultrasound (US) elastography in evaluating portal hypertension in children and compare the liver and spleen stiffness values between the portal hypertension and control groups.

METHODS

Studies in the MEDLINE and Embase databases were selected that investigated the diagnostic performance of US elastography in children with portal hypertension up to December 21, 2017. Pooled sensitivity and specificity data were assessed by hierarchical logistic regression modeling.

RESULTS

Eleven studies were included in the systematic review, and a meta-analysis could be conducted in 7 of these publications to evaluate the diagnostic performance of US elastography. The summary sensitivity and specificity of this method for liver stiffness were 90% (95% confidence interval [CI], 83%-94%) and 79% (95% CI, 73%-84%), respectively, and the area under the hierarchical summary receiver operating characteristic curve was 0.92 (95% CI, 0.90-0.94). A subgroup analysis of 5 transient elastographic studies revealed similar diagnostic performance (sensitivity, 90%; specificity, 78%). In 10 of the 11 studies that investigated liver stiffness and 2 of the 3 studies that also measured spleen stiffness, patients in the portal hypertension group had a significantly higher stiffness value than the control group (P < .05).

CONCLUSIONS

Ultrasound elastography shows good performance in diagnosing portal hypertension and can identify significant differences in liver and spleen stiffness in children with this condition. This method thus has considerable potential as a noninvasive tool for screening portal hypertension-related complications in children with chronic liver disease.

Noninvasive Evaluation of Liver Fibrosis and Portal Hypertension After Successful Portoenterostomy for Biliary Atresia

We investigated noninvasive follow‐up markers for histologic liver fibrosis and portal hypertension (PH) in patients with biliary atresia after successful portoenterostomy (PE). Among children with bilirubin <20 µmol/L after PE (n = 39), Metavir fibrosis stage was evaluated at PE and in follow‐up protocol liver biopsies (n = 83). PH was defined as endoscopically confirmed esophageal varices or thrombocytopenia associated with splenomegaly. The accuracy of liver biochemistry and stiffness in detecting liver fibrosis and PH was analyzed by the area under the receiving operating characteristic curve (AUROC) and multiple regression models. During a median native liver survival of 8.3 years (interquartile range 2.5‐10.8 years), cirrhosis (Metavir F4) had developed in 51% of patients and PH in 54% of patients. Cirrhosis was equally common in all age tertiles of 1.2‐2.1 years (n = 10/27), 3.9‐5.8 years (n = 12/28), and 9.0‐14 years (n = 12/28). In the two oldest age tertiles, histologic liver fibrosis had progressed further in patients with PH than without PH (P < 0.001). PH was accurately predicted by the aspartate aminotransferase‐to‐platelet ratio index (APRI) (cutoff, 0.70; AUROC, 0.92), bile acids (cutoff, 49 µmol/L; AUROC, 0.91), and liver stiffness (cutoff, 16.9 kPa; AUROC, 0.89; P < 0.001 each) across all age tertiles. Liver stiffness was the most accurate predictor of cirrhosis overall (AUROC, 0.82; P < 0.001), whereas bilirubin was >11 µmol/L in the youngest tertile (AUROC, 0.91; P < 0.001), bile acids was >80 µmol/L in the middle tertile (AUROC, 0.81; P = 0.009), and liver stiffness was >24 kPa in the oldest age tertile (AUROC, 0.96; P = 0.002). Conclusion: After successful PE, development of PH associates with progression of liver fibrosis and can be accurately detected by APRI and stiffness. Liver stiffness most accurately identified cirrhosis in older children, whereas biochemical markers of cholestasis closely reflected histologic cirrhosis in younger children.

Technical performance of shear wave elastography for measuring liver stiffness in pediatric and adolescent patients: a systematic review and meta-analysis

OBJECTIVE

To assess the technical performance (proportion of technical failure and unreliable measurements) of shear wave elastography (SWE) for assessing liver stiffness in pediatric and adolescent patients.

METHODS

We searched Ovid-MEDLINE and EMBASE databases for eligible studies and selected original articles investigating transient elastography (TE), point shear wave elastography (pSWE), or two-dimensional SWE (2D-SWE) for measuring liver stiffness in pediatric and adolescent patients. A quantitative synthesis of studies reporting technical failures and/or unreliable measurements of TE, pSWE, or 2D-SWE is presented. Meta-analytic pooling was conducted using the random effects model. Meta-regression analysis was conducted to explore potential causes of heterogeneity.

RESULTS

Forty of 69 studies (58%) provided technical performance information. Technical failure data were reported in 3 TE, 6 pSWE, and 8 2D-SWE studies. Unreliable measurement data were provided in 21 TE, 4 pSWE, and 1 2D-SWE study. The pooled proportion of unreliable measurements of TE was 12.1%. Meta-regression analysis showed that the study population size and readers' blinding to pathologic results affected the study's heterogeneity. The pooled proportions of technical failure during pSWE and 2D-SWE were 4.1% and 2.2%, respectively, demonstrating no significant difference between the techniques.

CONCLUSIONS

We reviewed the technical performance of SWE, especially the rate of unreliable measurements from TE studies and rates of technical failure from pSWE and 2D-SWE studies. Considering the importance of technical performance for clinical validation of SWE, numbers of and reasons for technical failure and unreliable measurements should be reported in future studies. Further efforts are necessary to standardize SWE reliability criteria.

KEY POINTS

• Most TE studies reported rate of unreliable measurements, whereas pSWE and 2D-SWE studies were likely to report rates of technical failure. • The pooled proportion of unreliable measurements of TE was 12.1%. • The pooled proportions of technical failure during pSWE and 2D-SWE were 4.1% and 2.2%, respectively, demonstrating no significant difference between the techniques.

Liver Ultrasound Elastography: An Update to the World Federation for Ultrasound in Medicine and Biology Guidelines and Recommendations

The World Federation for Ultrasound in Medicine and Biology has produced these guidelines for the use of elastography techniques in liver diseases. For each available technique, the reproducibility, results and limitations are analyzed, and recommendations are given. This set of guidelines updates the first version, published in 2015. Since the prior guidelines, there have been several advances in technology. The recommendations are based on the international published literature, and the strength of each recommendation is judged according to the Oxford Centre for Evidence-Based Medicine. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of liver diseases.

Transient Elastography Measurements of Spleen Stiffness as a Predictor of Clinically Significant Varices in Children

OBJECTIVES

Investigate the use of spleen stiffness measurements (SSMs), measured by transient elastography (TE), for the prediction of clinically significant varices (CSV) in children with portal hypertension.

METHODS

This observational cohort study included children selected for endoscopy, as per department protocol, between September 2015 and June 2016. Those included underwent single TE FibroScan for liver stiffness measurements and SSM. Clinical and laboratory data were collected and variceal prediction scores were calculated at time of elastography.

RESULTS

In total 67 children (32 boys) underwent TE. Fifty-two children (25 boys) had chronic liver disease (CLD), 15 (7 boys) portal vein thrombosis (PVT). In all children SSM was the best predictor of CSV+ve, with an optimal cut-off value of 38.0 kPa (area under the receiver operator curve [AUROC] = 0.92, sensitivity = 89%, specificity = 82%, P < 0.01). In the CLD group SSM was also the best predictor, with an optimal cut-off value of 38.05 kPa (AUROC = 0.90, sensitivity = 84%, specificity = 87%, P < 0.01). In the PVT group only SSM was predictive of CSV+ve, with an optimal cut-off value of 16.8 kPa (AUROC = 1.00, sensitivity = 100%, specificity = 100%, P < 0.001). For the prediction of GI bleeding (n = 6), liver stiffness measurement performed the best, with an optimal cut-off value of 34.3 kPa (AUROC = 0.84, sensitivity of 80%, specificity of 88%, P = 0.01).

CONCLUSIONS

SSM was the greatest predictor of CSV+ve in the whole cohort, and individual CLD and PVT groups. SSM could be used as a noninvasive screening tool for children with portal hypertension to stratify the risk of having CSV.

Non-invasive Markers of Portal Hypertension: Appraisal of Adult Experience and Potential Utilisation in Children

Portal hypertension (PHT) is a significant cause of morbidity and mortality in children with chronic liver disease and portal vein obstruction. Increased portal pressure results in variceal formation along the gastrointestinal (GI) tract resulting in major bleeding. Identifying children with significant PHT who are more likely to suffer GI bleeding has been challenging and the role of surveillance upper GI endoscopy has been debated. This review analyses research done on serum biomarkers and imaging techniques as possible predictors of significant PHT. We evaluated the research performed on adult population, as well as the limited work done on children, to identify promising areas for future research. A literature search was conducted on "PubMed." Several search terms were used including "portal hypertension," "paediatric portal hypertension," "non-invasive markers of portal hypertension," "spleen stiffness," "liver stiffness," "elastography," and "endothelial damage." The articles included were selected based on their relevance to the purpose of our review. The research suggests a combination of several biomarkers, in addition to an imaging technique such as transient elastography or magnetic resonance elastography, would allow for the best prediction of significant varices. The most promising indicators would be those that are applicable in both intra- and extra-hepatic causes of PHT. Further research on these predictors in children with PHT is required to determine their potential role as selection criteria for PHT and stratification of surveillance GI endoscopies.

Shear Wave Elastography as a Quantitative Biomarker of Clinically Significant Portal Hypertension: A Systematic Review and Meta-Analysis

OBJECTIVE

To qualify shear wave elastography (SWE) as a biomarker for clinically significant portal hypertension (CSPH) beyond proof of concept, we aimed to accumulate and summarize the current evidence through systematic review and meta-analysis.

MATERIALS AND METHODS

A computerized literature search was performed to identify studies from MEDLINE and EMBASE up to February 9, 2017. Studies on the diagnostic performance of liver stiffness measurements using SWE for CSPH with hepatic venous pressure gradient (HVPG) as the reference standard were included. Various aspects of SWE were comprehensively assessed. The summary diagnostic performance of SWE for the diagnosis of CSPH and the summary correlation coefficient between liver stiffness measured using SWE and HVPG were evaluated through a meta-analysis.

RESULTS

Nine articles (including 746 patients) were retrieved. The diagnostic performance of SWE for the diagnosis of CSPH was fairly good, with a summary sensitivity of 85% (95% CI, 75-91%; I² = 78.56%) and summary specificity of 85% (95% CI, 77-90%; I² = 0%); the area under the ROC curve was 0.88 (95% CI, 0.85-0.91). The summary correlation coefficient between liver stiffness and HVPG measurements was 0.741 (95% CI, 0.658-0.825; I² = 0%). These results support the value of SWE as a diagnostic biomarker for CSPH. However, there was significant heterogeneity in the imaging devices, protocols, liver stiffness measurement methods, and cutoff values used, which suggests that standardization is required.

CONCLUSION

The consistent evidence favoring SWE as a biomarker for CSPH should be considered in the biomarker qualification process and management of patients with CSPH.