Learning curve and interobserver reproducibility evaluation of liver stiffness measurement by transient elastography

Guided-VCTE: An Enhanced FibroScan Examination With Improved Guidance and Applicability

OBJECTIVE

Although FibroScan (FS), based on Vibration-Controlled Transient Elastography (VCTE), is a widely used non-invasive device for assessing liver fibrosis and steatosis, its current standard-VCTE examination remains timely and difficult on patients with obesity. The Guided-VCTE examination uses continuous shear waves to locate the liver by providing a real-time predictive indicator for shear wave propagation and uses shear wave maps averaging to increase the signal-to-noise ratio in difficult to assess patients. We aimed to evaluate the effectiveness of the new indicator, as well as compare examination times and success rates with both standard-VCTE and Guided-VCTE examinations.

METHODS

We recruited 130 patients all with varying BMI in this multicenter study. Sensitivity, specificity, positive predictive values and negative predictive values assessed the new indicator effectiveness. Success rates were compared using Wilcoxon signed rank tests rates and time-to-event analyses were used to investigate examination times. Agreement and repeatability of both methods were assessed using Wilcoxon signed-rank test.

RESULTS

The new indicator was highly effective, with a 97% sensitivity for predicting valid liver stiffness measurements (LSM). LSM and controlled attenuation parameter results remained in good agreement between two examinations. The Guided-VCTE examination significantly increased the success rate of individual measurements and significantly reduced the time required for localization in the study cohort, especially in patients with grade 2 obesity (BMI ≥35 kg/m²). Additionally, the proportion of patients scanned in less than 4 minutes was significantly higher with the Guided-VCTE examination.

CONCLUSION

Guided-VCTE is a new effective technique that simplifies further FS use, particularly for patients with obesity.

Oesophageal varices predict complications in compensated advanced non-alcoholic fatty liver disease

Background & Aims

We aimed to evaluate the impact of oesophageal varices (OV) and their evolution on the risk of complications of compensated advanced chronic liver disease (cACLD) caused by non-alcoholic fatty liver disease (NAFLD). We also assessed the accuracy of non-invasive scores for predicting the development of complications and for identifying patients at low risk of high-risk OV.

Methods

We performed a retrospective assessment of 629 patients with NAFLD-related cACLD who had baseline and follow-up oesophagogastroduodenoscopy and clinical follow-up to record decompensation, portal vein thrombosis (PVT), and hepatocellular carcinoma.

Results

Small and large OV were observed at baseline in 30 and 15.9% of patients, respectively. The 4-year incidence of OV from absence at baseline, and that of progression from small to large OV were 16.3 and 22.4%, respectively. Diabetes and a ≥5% increase in BMI were associated with OV progression. Multivariate Cox regression revealed that small (hazard ratio [HR] 2.24, 95% CI 1.47-3.41) and large (HR 3.86, 95% CI 2.34-6.39) OV were independently associated with decompensation. When considering OV status and trajectories, small (HR 2.65, 95% CI 1.39-5.05) and large (HR 4.90, 95% CI 2.49-9.63) OV at baseline and/or follow-up were independently associated with decompensation compared with the absence of OV at baseline and/or follow-up. The presence of either small (HR 2.8, 95% CI 1.16-6.74) or large (HR 5.29, 95% CI 1.96-14.2) OV was also independently associated with incident PVT.

Conclusion

In NAFLD-related cACLD, the presence, severity, and evolution of OV stratify the risk of developing decompensation and PVT.

Impact and implications

Portal hypertension is the main driver of liver decompensation in chronic liver diseases, and its non-invasive markers can help risk prediction. The presence, severity, and progression of oesophageal varices stratify the risk of complications of non-alcoholic fatty liver disease. Easily obtainable laboratory values and liver stiffness measurement can identify patients at low risk for whom endoscopy may be withheld, and can also stratify the risk of liver-related complications.

Agreement and reliability of hepatic transient elastography in patients with chronic hepatitis C: A cross-sectional test-retest study

Background and Aims

Transient elastography (TE) has largely replaced liver biopsy to evaluate fibrosis stage and cirrhosis in chronic hepatitis C. Previous studies have reported excellent reliability of TE but agreement metrics have not been reported. This study aimed to assess interrater agreement and reliability of repeated TE measurements.

Methods

Two operators performed TE independently, directly after each other. The primary outcome was disagreement, defined as a difference in TE results between operators of ≥33%, as well as the smallest detectable change, SDC95 (i.e., the difference between measurements needed to state with 95% certainty that there is a difference in underlying stiffness). Secondary outcomes included reliability, measured as intraclass correlation (ICC), and patient and examination characteristics associated with the agreement.

Results

In total, 65 patients were included, with a mean liver stiffness of 9.7 kPa. Of these, 21 (32%) had a disagreement in TE results of ≥33% between the two operators. The SDC95 on the log scale was 1.97, indicating that an almost twofold increase or decrease in liver stiffness would be required to confidently represent a change in the underlying fibrosis. Reliability, estimated using the ICC, was acceptable at 0.86. In a post hoc analysis, fasting less than 5 h before TE was associated with a higher degree of disagreement (48% vs. 19%, p = 0.03).

Conclusions

In our clinical setting, interrater agreement in directly repeated TE measurements was surprisingly low. It is essential to further investigate the reliability and agreement of TE to determine its validity and usefulness.

Factors Associated with Disagreement of Fibrosis Stages between 2D-Shear Wave Elastography and Transient Elastography in Chronic Hepatitis B

INTRODUCTION AND OBJECTIVES

The agreement of elastography techniques in chronic Hepatitis B (CHB) needs evaluation. We aimed to evaluate, in CHB, the agreement between transient elastography (TE) and two-dimensional shear wave elastography (2D-SWE), analyzing the factors related to the disagreement of measures.

MATERIALS AND METHODS

CHB patients underwent liver stiffness measures with both TE and 2D-SWE on the same day. For concordance analysis, we defined liver fibrosis as F0/1 vs. F ≥ 2, F0/1-F2 vs. F ≥ 3 and F0/1-F2-F3 vs. F4 for both methods. Logistic regression analysis was used to identify the variables independently associated with the disagreement between methods.

RESULTS

A total of 150 patients were enrolled. Liver fibrosis categorization according to TE was: F0-F1 = 73 (50.4%), F ≥ 2 = 40 (27.6%), F ≥ 3 = 21 (14.5%) and F4 = 11 (7.6%), and according to 2D-SWE was: F0/F1 = 113 (77.9%), F ≥ 2 = 32 (22.1%), F≥ 3 = 25 (17.2%) and F4 = 11 (7.6%). It was observed that 20.0% of the sample had steatosis (CAP≥ 275 dB/m). TE and SD-SWE estimated equal fibrosis stages in 79.3% of cases. Spearman's correlation coefficient was 0.71 (p < 0.01). Kappa values for F ≥ 2, F ≥ 3 and F = 4 were: 0.78, p < 0.001; 0.73, p < 0.001; and 0.64, p < 0.001, respectively. Diabetes mellitus (DM) (OR 5.04; 95%CI: 1.89-13.3; p < 0.001) and antiviral treatment (OR 6.79; 95%CI: 2.33-19.83; p < 0.001) were independently associated with discordance between both methods.

CONCLUSIONS

In CHB, there is strong correlation and good agreement between TE and 2D-SWE in identifying fibrosis stages. Diabetes mellitus and antiviral therapy may impact the agreement of stiffness measures obtained with these elastographic methods.

How to Identify Advanced Fibrosis in Adult Patients with Non-Alcoholic Fatty Liver Disease (NAFLD) and Non-Alcoholic Steatohepatitis (NASH) Using Ultrasound Elastography-A Review of the Literature and Proposed Multistep Approach

Non-alcoholic fatty liver disease (NAFLD), and its progressive form, non-alcoholic steatohepatitis (NASH), represent, nowadays, real challenges for the healthcare system. Liver fibrosis is the most important prognostic factor for NAFLD, and advanced fibrosis is associated with higher liver-related mortality rates. Therefore, the key issues in NAFLD are the differentiation of NASH from simple steatosis and identification of advanced hepatic fibrosis. We critically reviewed the ultrasound (US) elastography techniques for the quantitative characterization of fibrosis, steatosis, and inflammation in NAFLD and NASH, with a specific focus on how to differentiate advanced fibrosis in adult patients. Vibration-controlled transient elastography (VCTE) is still the most utilized and validated elastography method for liver fibrosis assessment. The recently developed point shear wave elastography (pSWE) and two-dimensional shear wave elastography (2D-SWE) techniques that use multiparametric approaches could bring essential improvements to diagnosis and risk stratification.

Assessment of Noninvasive Markers of Steatosis and Liver Fibrosis in HIV-monoinfected Patients on Stable Antiretroviral Regimens

Background

Nonalcoholic fatty liver disease (NAFLD) is a major nonacquired immune deficiency syndrome-defining condition for persons with human immunodeficiency virus (PWH). We aimed to validate noninvasive tests for the diagnosis of NAFLD in PWH.

Methods

This is a cross-sectional study of PWH on stable antiretroviral therapy with persistently elevated transaminases and no known liver disease. The area under the receiver operating characteristic curve (AUROC) was calculated to compare the diagnostic accuracy of liver biopsy with abdominal ultrasound, transient elastography (TE) (including controlled attenuation parameter [CAP]), and noninvasive markers of steatosis (triglyceride and glucose index [TyG], hepatic steatosis index [HSI], fatty liver index [FLI]) and fibrosis ([FIB]-4, aminotransferase-to-platelet ratio index [APRI], NAFLD fibrosis score). We developed a diagnostic algorithm with serial combinations of markers.

Results

Of 146 patients with increased transaminase levels, 69 underwent liver biopsy (90% steatosis, 61% steatohepatitis, and 4% F ≥3). The AUROC for steatosis was as follows: ultrasound, 0.90 (0.75–1); CAP, 0.94 (0.88–1); FLI, 0.81 (0.58–1); HSI, 0.74 (0.62–0.87); and TyG, 0.75 (0.49–1). For liver fibrosis ≥F3, the AUROC for TE, APRI, FIB-4, and NAFLD fibrosis score was 0.92 (0.82–1), 0.96 (0.90–1), 0.97 (0.93–1), and 0.85 (0.68–1). Optimal diagnostic performance for liver steatosis was for 2 noninvasive combined models of tests with TyG and FLI/HSI as the first tests and ultrasound or CAP as the second tests: AUROC = 0.99 (0.97–1, P < .001) and 0.92 (0.77–1, P < .001).

Conclusions

Ultrasound and CAP performed best in diagnosing liver steatosis, and FLI, TyG, and HSI performed well. We propose an easy-to-implement algorithm with TyG or FLI as the first test and ultrasound or CAP as the second test to accurately diagnose or exclude NAFLD.

Quality criteria for the measurement of liver stiffness

Liver elastography offers the possibility of a quick, non-invasive, and painless evaluation of the liver with immediate results at bedside. Transient elastography is the most validated technology, and many others such as point shear wave elastography, 2D-shear wave elastography, or magnetic resonance elastography have been developed. To ensure the best evaluation, several conditions of examination must be respected for liver stiffness measurement. Indeed, patient, operator and examination characteristics have all been shown to influence the result of liver stiffness measurement. Food intake increases liver stiffness, whereas withdrawal in alcoholics is associated with a decrease in elastography results. Inter-observer reproducibility of the measurement seems suboptimal, and the influence of the operator experience is still being debated. The measurement site and the FibroScan® probe must be correctly chosen. Finally, the intrinsic characteristics and quality criteria of the measurement, especially the interquartile range/median ratio, must be carefully checked to avoid overestimation of liver stiffness. Most of the results come from studies which have evaluated transient elastography, with less data available for the other technologies. Liver stiffness measurement could appear as a simple way to explore the liver, but several conditions must be met before deciding the patient management according to its result.

The role of elastography in viral hepatitis and autoimmune hepatitis

The prognosis of chronic liver diseases, which represent a major public health problem, is mainly linked to the extent and progression of liver fibrosis and the subsequent risk of developing cirrhosis and related complications, mainly hepatocellular carcinoma. During the past decade many noninvasive methods and in particular electrographic techniques, have been developed to reduce the need for liver biopsy in staging fibrosis and to overcome whenever possible its limitations, mainly: invasiveness, costs, low reproducibility and poor acceptance by patients. The aim of this review was to provide a comprehensive review of the role of elastography techniques in viral chronic liver diseases and autoimmune hepatitis, with the focus on the possible advantages and limitations of these techniques and on their diagnostic accuracy in predicting the stage of liver fibrosis.

[Magnetic resonance elastography of the liver : Worth knowing for clinical routine]

BACKGROUND

Magnetic resonance elastography (MRE) is a noninvasive, quantitative, MRI-based method to evaluate liver stiffness. Beside biopsy and ultrasound elastography, this imaging method plays in many places a significant role in the detection and additive characterization of chronic liver disease.

OBJECTIVES, MATERIALS AND METHODS

Based on the literature, a brief review of the underlying method and the commercially available products is given. Furthermore, the practical procedure, the analysis, and the interpretation of clinically relevant questions are illustrated and a comparison with ultrasound elastography is provided.

RESULTS

This relative "young" MRI method allows extensive evaluation of mechanical properties of the liver and is an important diagnostic tool especially in follow-up examinations. The MRE of the liver is with a maximum technical failure rate of 5.8% a robust technique with high accuracy and an excellent re-test reliability as well as intra- and interobserver reproducibility. There is a high diagnostic certainty within the framework of most important clinical indications, the quantification of fibrosis, and with a very good correlation with the "gold standard" biopsy.

CONCLUSION

Based on its rising clinical relevance and the broad usage, MRE of the liver is increasingly used in many centers and in routine liver protocols. Therefore, basic knowledge of this method is essential for every radiologist.

Association between behavioural risk factors for chronic liver disease and transient elastography measurements across the UK: a cross-sectional study

OBJECTIVE

Chronic liver disease (CLD) is a largely preventable condition with increasing burden on National Health Service resources. We aimed to determine the prevalence of behavioural risk factors for CLD and their association with liver stiffness and socioeconomic status in the UK.

DESIGN

In this cross-sectional study, adults aged ≥18 years were invited to complete a liver health screener and have a liver stiffness measurement (LSM) by transient elastography (TA) to screen for alcohol intake, obesity and viral hepatitis risk across different areas in the UK. Index of Multiple Deprivation (IMD) scores were used as a measure of socioeconomic status. We performed binary logistic regression, adjusting for age, gender, alcohol consumption, body mass index, diet and viral hepatitis risk to determine the factors associated with LSM and IMD.

RESULTS

We analysed the data from 2150 individuals across 25 UK areas. Of those, 24.1% had high-risk alcohol consumption, 29.6% had high-risk diets, 24.7% were obese and 32.7% had risk factors for viral hepatitis. LSMs were available for 1043 participants, of which 16.2% were ≥7 kPa. Independent predictors of an LSM≥7 kPa were an age≥40 years (OR, 1.986; 95% CI, 1.280 to 3.081), male gender (OR, 1.599; 95% CI, 1.128 to 2.266), obesity (OR, 2.526; 95% CI, 1.383 to 4.614) and high-risk diet (OR, 2.197; 95% CI, 1.000 to 4.826). Five-unit increases in IMD score were an independent predictor of obesity (OR, 1.110; 95% CI, 1.028 to 1.200), but not high-risk alcohol consumption (p=0.88) or viral hepatitis risk (p=0.05).

CONCLUSIONS

We identified a high prevalence of risk factors for CLD, most of which are addressable through raising public awareness to inculcate healthy habits. More studies are needed to assess longitudinal outcomes of liver screening using TA, accounting for societal factors and comorbidities, to help inform resource allocation and policy-making in the future.

The Role of Spleen and Liver Elastography and Color-Doppler Ultrasound in the Assessment of Transjugular Intrahepatic Portosystemic Shunt Function

The reference standard for assessing transjugular intrahepatic portosystemic shunt (TIPS) function is venography with portosystemic pressure gradient (PPG) measurement. This procedure is invasive and expensive; thus, we assessed the feasibility, reproducibility and diagnostic accuracy of color-Doppler ultrasound (CDUS) and spleen and liver stiffness (LS) measurements for identifying TIPS dysfunction. Twenty-four patients (15 undergoing TIPS placement and nine undergoing TIPS revision) consecutively underwent CDUS examination and LS and spleen stiffness (SS) determination by transient elastography (TE) and point shear-wave elastography (pSWE). All parameters were taken before TIPS placement/revision (1-15 d before) and 24 h after, just before revision by venography. pSWE inter-observer agreement was assessed by intra-class correlation coefficient (ICC). CDUS and elastographic data were correlated (Pearson coefficient) with pressure gradients (hepatic venous pressure gradient [HVPG], PPG). Main determinants of TIPS dysfunction were investigated by linear regression. Forty-nine paired examinations were performed in total: 49 (100%) SS reliable measurements by pSWE and 38 (88%) by TE. The ICC for pSWE values was 0.90 (95% confidence interval [CI] 0.81‒0.94). SS values significantly correlated with HVPG and PPG (R = 0.51, p = 0.01). The area under the Receiver-Operating Characteristic (AUROC) curve of SS for diagnosing TIPS dysfunction was 0.86 (95% CI 0.70‒0.96) using a 25 kPa cutoff. At multivariate analysis, the flow direction of the intrahepatic portal vein branches and SS values were independently associated to TIPS dysfunction. The intrahepatic portal vein branches flow direction and SS value are two simple, highly sensitive parameters accurately excluding TIPS dysfunction. SS measurement by pSWE is feasible, reproducible and both positively and significantly correlates with HVPG and PPG values.

Noninvasive diagnosis in alcohol-related liver disease

Background

Alcohol‐related liver disease (ALD) represents a major cause of death worldwide, and unfortunately, most patients are diagnosed at an advanced stage of the disease, which is related to poorer outcomes. Liver biopsy has historically been the gold standard for identifying advanced hepatic fibrosis, but this approach has several limitations, including invasiveness, low applicability, sampling variability, and cost.

Main Text

In order to detect earlier features of advanced liver fibrosis, surrogate biomarkers and techniques have been developed. While these were initially developed for chronic liver diseases such as viral hepatitis and nonalcoholic fatty liver disease (NAFLD), their performance in ALD has also been recently studied. Among the noninvasive surrogate markers and techniques used to detect liver fibrosis, the Enhanced Liver Fibrosis test, FibroTest, and Transient Elastography are the most accurate and validated techniques. In this review, we summarize the current status of the noninvasive assessment of liver disease in ALD and provide a synthesis of how these noninvasive tools can be used in clinical practice. Finally, we briefly outline novel biomarkers that are currently being investigated and discuss future directions and new opportunities in the noninvasive diagnosis of ALD.

Liver fibrosis by FibroScan® independently of established cardiovascular risk parameters associates with macrovascular and microvascular complications in patients with type 2 diabetes

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) are closely associated, and liver fibrosis has been related to macrovascular complications. We examined whether liver fibrosis, diagnosed by FibroScan^® , correlates with chronic vascular complications in a cohort of T2DM.

METHODS

We recruited 394 outpatients with T2DM attending five Italian diabetes centres who underwent liver ultrasonography (US), FibroScan^® and extensive evaluation of macrovascular and microvascular diabetic complications.

RESULTS

Steatosis by US was present in 89%. Almost all patients (96%) were on hypoglycaemic drugs, 58% had at least one chronic vascular complication, 19% a macrovascular complication (prior myocardial infarction and/or ischaemic stroke) and 33% a microvascular one (26% chronic kidney disease [CKD]; 16% retinopathy; 6% neuropathy). In all, 171 (72%) patients had CAP ≥ 248dB/m (ie hepatic steatosis), whereas 83 (21%) patients had LSM ≥ 7.0/6.2 kPa (M/XL probes) (significant liver fibrosis). CAP was not associated with any macro/microvascular complications, whereas LSM ≥ 7.0/6.2 kPa was independently associated with prior cardiovascular disease (adjusted OR 3.3, 95%CI 1.2-8.8; P = .02) and presence of microvascular complications (adjusted OR 4.2, 95%CI 1.5-11.4; P = .005), mainly CKD (adjusted OR 3.6, 95%CI 1.3-10.1; P = .01) and retinopathy (adjusted OR 3.7, CI 95% 1.2-11.9; P = .02). Neither diabetes duration nor haemoglobin A1c differed according to CAP or LSM values.

CONCLUSION

Significant fibrosis, detected by FibroScan^® , is independently associated with increased prevalence of macrovascular and microvascular complications, thus opening a new scenario in the use of this tool for a comprehensive evaluation of hepatic and vascular complications in patients with T2DM.

Liver fibrosis imaging: A clinical review of ultrasound and magnetic resonance elastography

Liver fibrosis is a histological hallmark of most chronic liver diseases, which can progress to cirrhosis and liver failure, and predisposes to hepatocellular carcinoma. Accurate diagnosis of liver fibrosis is necessary for prognosis, risk stratification, and treatment decision-making. Liver biopsy, the reference standard for assessing liver fibrosis, is invasive, costly, and impractical for surveillance and treatment response monitoring. Elastography offers a noninvasive, objective, and quantitative alternative to liver biopsy. This article discusses the need for noninvasive assessment of liver fibrosis and reviews the comparative advantages and limitations of ultrasound and magnetic resonance elastography techniques with respect to their basic concepts, acquisition, processing, and diagnostic performance. Variations in clinical contexts of use and common pitfalls associated with each technique are considered. In addition, current challenges and future directions to improve the diagnostic accuracy and clinical utility of elastography techniques are discussed. Level of Evidence: 5 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:25-42.

A review of the use of transient elastography in the assessment of fibrosis and steatosis in the post-liver transplant patient

Liver biopsy is considered the gold standard method for diagnosing and staging liver disease, particularly in the post-liver transplant setting. Given the invasive nature of biopsy, alternate means for accurately assessing liver fibrosis and steatosis are preferred especially as the number of patients with fatty liver disease is increasing. Transient elastography has been validated as a useful tool for evaluation of liver fibrosis, as has controlled attenuation parameter index as a tool for assessing steatosis. It is a non-invasive, rapid, and highly reproducible approach to demonstrate the presence of fibrosis among non-transplant patients with chronic liver disease of various etiologies. However, it has not yet found wide acceptance in liver transplant recipients. There are few published studies evaluating the merits and applicability of transient elastography to assess allografts after liver transplantation. We review the published data on the use of transient elastography with concurrent controlled attenuation parameter in liver transplant recipients and recommend its greater use to follow allograft function over time.

Reproducibility of 2 Liver 2-Dimensional Shear Wave Elastographic Techniques in the Fasting and Postprandial States

OBJECTIVES

The purpose of this study was to compare the reliability and agreement of 2 methods of 2-dimensional (2D) shear wave elastography (SWE) on liver stiffness in healthy volunteers. We also assessed effects of the prandial state and operator experience on measurements.

METHODS

Two operators, 1 experienced and 1 novice, independently examined 20 healthy volunteers with 2D SWE on 2 ultrasound machines (Aixplorer [SuperSonic Imagine, Aix-en-Provence, France] and Aplio 500 [Canon Medical Systems Corporation, Otawara, Japan]). Volunteers were scanned 8 times by the operators using both machines in fasting and postprandial states. Agreement was evaluated by a Bland-Altman analysis, and the correlation was assessed by the Pearson correlation and intraclass correlation coefficients (ICCs). An analysis of variance was conducted to determine the contribution of the machine, prandial state, and operator experience to the variability.

RESULTS

Agreement assessed by Bland-Altman plots showed no statistically significant difference in measured liver stiffness between the machines (mean difference, -0.8%; 95% confidence interval, -3.7%, 2.1%), with a critical difference of 1.36 kPa. The correlation was good to excellent for both the crude overall Pearson coefficient and the ICC, both measuring 0.88 (95% confidence interval, 0.82, 0.92). Subclass ICCs for the fasting state, postprandial state, novice operator, and experienced operator were 0.89, 0.88, 0.90, and 0.86, respectively. The 2-way mixed effect analysis of variance showed that the volunteers accounted for 86.3% of variation in median liver stiffness, with no statistically significant contribution from operator experience, the prandial state, or the machine (P = .108, .067, and .296, respectively).

CONCLUSIONS

Our study showed that the 2D SWE techniques had a high degree of reliability and agreement in measurement of liver stiffness in a healthy population. Operator experience and the prandial state did not impart significant variability to stiffness measurements.

Impact of Obesity and Alanine Aminotransferase Levels on the Diagnostic Accuracy for Advanced Liver Fibrosis of Noninvasive Tools in Patients With Nonalcoholic Fatty Liver Disease

INTRODUCTION

Some evidence suggests an interference of obesity and alanine aminotransferase (ALT) levels on the diagnostic accuracy for advanced fibrosis of noninvasive tools such as liver stiffness measurement (LSM) by FibroScan, Fibrosis-4 (FIB-4), and nonalcoholic fatty liver disease fibrosis score (NFS). We assessed whether the diagnostic accuracy of LSM, Fibrosis-4 (FIB-4), and NFS and strategies based on the combination of these tools is affected by obesity and/or ALT levels.

METHODS

We analyzed data from 968 patients with a histological diagnosis of nonalcoholic fatty liver disease. FIB-4, NFS, and LSM by FibroScan were measured.

RESULTS

LSM was better than both FIB-4 and NFS for staging F3-F4 fibrosis area under the receiver operating characteristic curve test (AUC) 0.863, 0.777, and 0.765, respectively; P < 0.001 for both), showing higher accuracy and higher negative predictive value (NPV), but lower positive predictive value (PPV). LSM worked less well in high ALT (>100 IU) (AUC 0.811 vs 0.877, P = 0.04; PPV 57.5% vs 62.4%; NPV 90.7% vs 94%) or obese patients (AUC 0.786 vs 0.902, P < 0.001; PPV 58.7% vs 64.8%; NPV 88.3% vs 95.2%), the latter not being affected by the M or XL probe. Consistently, LSM worked better in terms of AUC and accuracy compared with both FIB-4 and NFS only in nonobese or high ALT patients, even with always keeping a slightly lower PPV. A serial combination of FIB-4 or NFS with LSM as the second test in patients in the gray area of the first test retained-in most scenarios-similar PPV and NPV compared with LSM alone. These strategies also increased the diagnostic accuracy of about 20% in all groups of patients, even if with a lower overall accuracy in obese patients (71.3% and 67.1% for FIB-4 and NFS as the first test, respectively) compared to nonobese patients (81.9% and 82.4% for FIB-4 and NFS as the first test, respectively).

CONCLUSIONS

All tested noninvasive tools have overall better NPV than PPV. LSM has a better diagnostic accuracy for advanced fibrosis than both FIB-4 and NFS only in nonobese and/or low ALT patients. Serial combination strategies are better than a single tool strategy, regardless of obesity and ALT levels, although the accuracy is lower in obese patients.

Criteria to Determine Reliability of Noninvasive Assessment of Liver Fibrosis With Virtual Touch Quantification

BACKGROUND & AIMS

Virtual Touch Quantification (VTQ) evaluates liver fibrosis in patients with chronic liver diseases by measuring shear wave speed in the liver. We aimed to determine the reliability criteria of VTQ examination.

METHODS

We performed a prospective study of 1094 patients with chronic liver disease from November 2009 through October 2016 at Angers University Hospital, and between April 2010 and May 2015 at Bordeaux University Hospital, in France. All patients underwent liver biopsy analysis (reference standard), and VTQ examination was made by experienced operators on the same day, or no more than 3 months before or afterward. Advanced liver fibrosis was defined as fibrosis stage F ≥ 3 according to the scoring system of the Nonalcoholic Steatohepatitis Clinical Research Network, or fibrosis stage F ≥ 2 according to the Metavir scoring system. The diagnostic accuracy of VTQ in detection of advanced fibrosis or cirrhosis was assessed using the area under the receiver operating characteristic (AUROC) and the rate of correctly classified patients. Reliability criteria were defined from the intrinsic characteristics of VTQ examination, which were shown to influence the diagnostic accuracy.

RESULTS

VTQ identified patients with advanced fibrosis with an AUROC of 0.773 ± 0.014 and correctly classified 72.0% of patients using a diagnostic cut-off value of 1.37 m/s. VTQ identified patients with cirrhosis with an AUROC value of 0.839 ± 0.014 and correctly classified 78.4% of patients using a cut-off value of 1.87 m/s. The reliability of VTQ decreased with an increasing ratio of interquartile range/median (IQR/M) in patients with intermediate-high VTQ results. We defined 3 reliability categories for VTQ: unreliable (IQR/M ≥0.35 with VTQ result ≥1.37 m/s), reliable (IQR/M ≥0.35 with VTQ result <1.37 m/s or IQR/M 0.15-0.34), and very reliable (IQR/M <0.15). For advanced fibrosis, VTQ correctly classified 57.8% of patients in the unreliable group, 73.7% of patients in the reliable group, and 80.9% of patients in the very reliable group (P < .001); for cirrhosis, these values were 50.0%, 83.4%, and 92.6%, respectively (P < .001). Of the VTQ examinations made, 21.4% were unreliable, 55.0% were reliable, and 23.6% were very reliable. The skin-liver capsule distance was independently associated with an unreliable VTQ examination, which occurred in 52.7% of patients with a distance of 30 mm or more.

CONCLUSIONS

In a study to determine the reliability of VTQ findings, compared with results from biopsy analysis, we assigned VTQ examinations to 3 categories (unreliable, reliable, and very reliable). VTQ examinations with IQR/M ≥0.35 and ≥1.37 m/s had very low diagnostic accuracy. Our reliability criteria for liver fibrosis assessment with VTQ will help physicians to accurately evaluate the severity of chronic liver diseases and monitor their progression.

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.

Non-invasive prediction of esophageal varices by stiffness and platelet in non-alcoholic fatty liver disease cirrhosis

BACKGROUND & AIMS

Baveno VI and expanded Baveno VI criteria can avoid the need for esophagogastroduodenoscopy (EGD) to screen for varices needing treatment (VNT) in a substantial proportion of compensated patients with viral and/or alcoholic cirrhosis. This multicenter, cross-sectional study aims to validate these criteria in patients with compensated cirrhosis due to non-alcoholic fatty liver disease (NAFLD), accounting for possible differences in liver stiffness measurement (LSM) values between M and XL probes.

METHODS

We assessed 790 patients with NAFLD-related compensated cirrhosis who had EGD within six months of a reliable LSM, measured by FibroScan® using M and/or XL probe. Baveno VI and expanded Baveno VI criteria were tested. The main variable used to optimize criteria was the percentage of endoscopies spared, keeping the risk of missing large VNT below a 5% threshold.

RESULTS

LSM was measured by both M and XL probes (training set) in 314 patients, while only M or XL probe (validation sets) were used to measure LSM in 338 and 138 patients, respectively. In the training set, use of Baveno VI and expanded Baveno VI criteria reduced the number of EGD by 33.3% and by 58%, with 0.9% and 3.8% of large esophageal varices missed, respectively. The best thresholds to rule-out VNT were identified as platelet count >110,000/mm³ and LSM <30 kPa for M probe, and platelet count >110,000/mm³ and LSM <25 kPa for XL probe (NAFLD cirrhosis criteria). Thus, usage of NAFLD cirrhosis criteria would have led to an absolute reduction in the number of EGD screened patients of 34.7% and 10.5% with respect to Baveno VI and expanded Baveno VI criteria, respectively.

CONCLUSION

The new NAFLD cirrhosis criteria, established for the FibroScan probe, can reduce the use of EGD for screening of VNT in NAFLD cirrhosis by more than half, with a chance of missing VNT below 5%.

LAY SUMMARY

In non-alcoholic fatty liver disease-related compensated cirrhosis, the expanded Baveno VI criteria work better than the Baveno VI criteria for ruling out the presence of varices needing treatment, sparing unnecessary and invasive screening procedures. New diagnostic criteria for this patient group, based on liver stiffness measurement and platelet count, and optimized for the specific FibroScan^® probe used, work better than both Baveno VI and expanded Baveno VI criteria. The accuracy of all non-invasive scoring criteria was lower in non-obese patients.

Point quantification elastography in the evaluation of liver elasticity in healthy volunteers: a reliability study based on operator expertise

PURPOSE

The assessment of liver fibrosis is essential in the management of patients with chronic liver diseases. Liver biopsy is considered the gold standard procedure for this purpose, though the recent development of new elastosonographic techniques to measure liver stiffness (LS) noninvasively is promising. Point quantification elastography (PQE) showed good results but less is known about the level of skill needed to obtain reliable results. The aim of the study was to evaluate the reproducibility of PQE in assessing LS in healthy subjects comparing three operators with different expertise.

METHODS

Between December 2012 and April 2013, 50 consecutive healthy volunteers (18 males, 32 females), median age 30 years (range 25-66) and BMI 22.4 (range 16.7-33.6) were submitted to PQE (iU22 Philips, Bothell, WA, USA) by three operators: two US and elastography providers (one expert and one with intermediate skill) and a skilled transient elastography (Fibroscan) operator with no expertise in US. Intra- and inter-observer agreements were assessed by intraclass correlation coefficient (ICC).

RESULTS

PQE measurement was obtained in all subjects by all evaluators. No significant differences of mean liver stiffness were found among operators (P = 0.980). Intra-observer agreement was excellent 0.918 (0.941 for expert, 0.917 for intermediate and 0.888 for novice). The ICC of the inter-observer agreement among the three ratters was excellent (0.882) and was higher in normal than overweight patients (0.923 vs. 0.603; P = 0.011).

CONCLUSION

PQE is a reliable and reproducible non-invasive method for the assessment of LE, and can be performed also by a non-experienced operator.

Rapid change of liver stiffness after variceal ligation and TIPS implantation

Liver stiffness (LS) as measured by transient elastography is widely used to screen for liver fibrosis. However, LS also increases in response to pressure changes like congestion but no data on portal pressure are available. We study here the effect of rapid portal pressure changes on LS. Therefore, LS was assessed directly prior and after ligation of esophageal varices ( n = 11) as well as transjugular intrahepatic portosystemic shunt (TIPS) implantation in patients with established cirrhosis ( n = 14). Additionally, we retrospectively analyzed changes in LS and variceal size in patients with sequential gastroscopic monitoring and LS measurements ( n = 14). To study LS and portal pressure in healthy livers, LS (µFibroscan; Echosens, Paris, France) and invasive pressures (Powerlab, AD Instruments, New Zealand) were assessed in male Wistar rats after ligation of single liver lobes. Ligation of esophageal varices caused an immediate and significant increase of LS from 40.3 ± 19.0 to 56.1 ± 21.5 kPa. Likewise, LS decreased significantly from 53.1 ± 16.6 to 43.8 ± 17.3 kPa after TIPS placement, which correlated significantly with portal pressure ( r = 0.558). In the retrospective cohort, the significant LS decrease from 54.9 ± 23.5 to 47.9 ± 23.8 kPa over a mean observation interval of 4.3 ± 3 mo was significantly correlated with a concomitant increase of variceal size ( r = -0.605). In the animal model, LS and portal pressure increased significantly after single lobe ligation without changes of arterial or central venous pressure. In conclusion, rapid changes of portal pressure are a strong modulator of LS in healthy and cirrhotic organs. In patients with stable cirrhosis according to the model for end-stage liver disease (MELD), a decrease of LS may be indicative for enlarging varices. NEW & NOTEWORTHY Liver stiffness (LS) immediately increases after variceal ligation while it decreases after transjugular intrahepatic portosystemic shunt (TIPS) implantation due to portal pressure changes. LS and portal pressure rapidly increase after single lobe ligation in Wistar rats without changes of arterial or central venous pressure. Collateral formation may be one cause for a transient decrease in LS in the absence of other confounders. Such pressure changes should be considered when interpreting LS in clinical practice.

Reduced risk of hepatocellular carcinoma by achieving a subcirrhotic liver stiffness through antiviral agents in hepatitis B virus-related advanced fibrosis or cirrhosis

BACKGROUND AND AIM

A subcirrhotic range of liver stiffness (sc-LS), assessed by transient elastography, is associated with better outcomes in patients with chronic hepatitis B (CHB). We investigated whether the achievement of sc-LS by antiviral therapy (AVT) reduced the risk of developing hepatocellular carcinoma (HCC) in patients with CHB-related advanced fibrosis or cirrhosis.

METHODS

In total, 209 patients with CHB-related advanced fibrosis or cirrhosis, who received paired transient elastography examinations during AVT between 2007 and 2012, were enrolled. The cut-off LS value for ultrasonographic cirrhosis was defined as 11.6 kPa.

RESULTS

The median age of the study population was 51 years, with males predominating (n = 138, 66.0%). The median LS value at enrollment was 14.1 kPa (interquartile range: 9.5-24.1 kPa). After 2 years of AVT, 140 (67.0%) patients achieved sc-LS. During the study period, 28 (13.4%) patients developed HCC after 2 years of AVT. On multivariate analysis, the achievement of sc-LS after AVT was independently associated with a decreased risk of HCC development (hazard ratio [HR] = 0.485, P = 0.047), whereas older age (HR = 1.071) and male gender (HR = 3.704) were independently associated with an increased HCC risk (both P < 0.05). Patients with a cirrhotic range of LS value after 2 years of AVT were at a higher risk of HCC development than those with sc-LS (log-rank test, P = 0.020).

CONCLUSIONS

The achievement of sc-LS after AVT can reduce the risk of HCC development in patients with CHB, even when advanced fibrosis or cirrhosis is apparent on starting AVT.

Validation of risk prediction models for the development of HBV-related HCC: a retrospective multi-center 10-year follow-up cohort study

Recently, modified REACH-B (mREACH-B) risk prediction model for hepatocellular carcinoma (HCC) development was proposed. We validated the accuracy of the mREACH-B model and compared its accuracy with those of other prediction models. Between 2006 and 2012, 1,241 patients with chronic hepatitis B (CHB) were recruited. All patients underwent transient elastography at enrollment. The median age of the study population (840 males, 401 females) was 49 years. The median PAGE-B, LSM-HCC, and mREACH-B values were 10, 10, and 8, respectively. Among patients without cirrhosis (n = 940, 75.7%), the median REACH-B value was 9. During the follow-up period (median 77.4 months), 66 (5.3%) and 83 (6.7%) patients developed HCC and liver-related events (LRE), respectively. Higher liver stiffness (LS) independently predicted HCC (hazard ratio [HR] = 1.047) and LRE development (HR = 1.047) (all P < 0.05). The mREACH-B significantly predicted HCC (AUC = 0.824 at 3-year and 0.750 at 5-year) and LRE development (AUC = 0.782 at 3-year and 0.739 at 5-year) (all P < 0.001) and it performed similarly or significantly better than the PAGE-B and LSM-HCC (AUC = 0.715-0.809 at 3-year and 0.719-0.742 at 5-year for HCC; AUC = 0.704-0.777 at 3-year and 0.721-0.735 at 5-year for LRE). Among patients without cirrhosis, mREACH-B predicted HCC (AUC = 0.803 vs. 0.654-0.816 at 3-year and 0.684 vs. 0.639-0.738 at 5-year) and LRE development (AUC = 0.734 vs. 0.619-0.789 at 3-year and 0.674 vs. 0.626-0.729 at 5-year) similarly to PAGE-B, REACH-B, and LSM-HCC. mREACH-B appropriately predicted HCC and LRE development in patients with CHB and showed similar or superior accuracy to those of PAGE-B, REACH-B, and LSM-HCC.

MR Spectroscopy-derived Proton Density Fat Fraction Is Superior to Controlled Attenuation Parameter for Detecting and Grading Hepatic Steatosis

Purpose To prospectively compare the diagnostic accuracy of controlled attenuation parameter (CAP) obtained with transient elastography and proton density fat fraction (PDFF) obtained with proton magnetic resonance (MR) spectroscopy with results of liver biopsy in a cohort of adult patients suspected of having nonalcoholic fatty liver disease (NAFLD). Materials and Methods The institutional review board approved this study. Informed consent was obtained from all patients. The authors evaluated 55 patients suspected of having NAFLD (40 men, 15 women). Patients had a median age of 52.3 years (interquartile range [IQR], 43.7-57.6 years) and a median body mass index of 27.8 kg/m² (IQR, 26.0-33.1 kg/m²). CAP and PDFF measurements were obtained on the same day, within 27 days of biopsy (IQR, 7-44 days). CAP and PDFF were compared between steatosis grades by using the Jonckheere-Terpstra test. Diagnostic accuracies of CAP and PDFF for grading steatosis were assessed with receiver operating characteristic (ROC) analysis. Within-weeks reproducibility (CAP and PDFF) and within-session repeatability were assessed with linear regression analyses, intraclass correlation coefficients, and coefficients of variation. Results Steatosis grades at liver biopsy were distributed as follows: S0, five patients; S1, 24 patients; S2, 17 patients; and S3, nine patients. Both PDFF and CAP helped detect histologically proven steatosis (≥S1), but PDFF showed better diagnostic accuracy than CAP in terms of the area under the ROC curve (0.99 vs 0.77, respectively; P = .0334). PDFF, but not CAP, enabled the grading of steatosis (P < .0001). For within-weeks reproducibility, the intraclass correlation coefficient with PDFF was higher than that with CAP (0.95 vs 0.65, respectively; P = .0015); coefficients of variation were similar (19% vs 11%, P = .55). Within-session repeatability of CAP was good, with a coefficient of variation of 4.5%. Conclusion MR spectroscopy-derived PDFF is superior to CAP in detecting and grading liver steatosis in human NAFLD. ^© RSNA, 2017 Online supplemental material is available for this article.

Serial combination of non-invasive tools improves the diagnostic accuracy of severe liver fibrosis in patients with NAFLD

BACKGROUND

The accuracy of available non-invasive tools for staging severe fibrosis in patients with nonalcoholic fatty liver disease (NAFLD) is still limited.

AIM

To assess the diagnostic performance of paired or serial combination of non-invasive tools in NAFLD patients.

METHODS

We analysed data from 741 patients with a histological diagnosis of NAFLD. The GGT/PLT, APRI, AST/ALT, BARD, FIB-4, and NAFLD Fibrosis Score (NFS) scores were calculated according to published algorithms. Liver stiffness measurement (LSM) was performed by FibroScan.

RESULTS

LSM, NFS and FIB-4 were the best non-invasive tools for staging F3-F4 fibrosis (AUC 0.863, 0.774, and 0.792, respectively), with LSM having the highest sensitivity (90%), and the highest NPV (94%), and NFS and FIB-4 the highest specificity (97% and 93%, respectively), and the highest PPV (73% and 79%, respectively). The paired combination of LSM or NFS with FIB-4 strongly reduced the likelihood of wrongly classified patients (ranging from 2.7% to 2.6%), at the price of a high uncertainty area (ranging from 54.1% to 58.2%), and of a low overall accuracy (ranging from 43% to 39.1%). The serial combination with the second test used in patients in the grey area of the first test and in those with high LSM values (>9.6 KPa) or low NFS or FIB-4 values (<-1.455 and <1.30, respectively) overall increased the diagnostic performance generating an accuracy ranging from 69.8% to 70.1%, an uncertainty area ranging from 18.9% to 20.4% and a rate of wrong classification ranging from 9.2% to 11.3%.

CONCLUSION

The serial combination of LSM with FIB-4/NFS has a good diagnostic accuracy for the non-invasive diagnosis of severe fibrosis in NAFLD.

Improved noninvasive prediction of liver fibrosis by liver stiffness measurement in patients with nonalcoholic fatty liver disease accounting for controlled attenuation parameter values

Liver stiffness measurement (LSM) frequently overestimates the severity of liver fibrosis in nonalcoholic fatty liver disease (NAFLD). Controlled attenuation parameter (CAP) is a new parameter provided by the same machine used for LSM and associated with both steatosis and body mass index, the two factors mostly affecting LSM performance in NAFLD. We aimed to determine whether prediction of liver fibrosis by LSM in NAFLD patients is affected by CAP values. Patients (n = 324) were assessed by clinical and histological (Kleiner score) features. LSM and CAP were performed using the M probe. CAP values were grouped by tertiles (lower 132-298, middle 299-338, higher 339-400 dB/m). Among patients with F0-F2 fibrosis, mean LSM values, expressed in kilopascals, increased according to CAP tertiles (6.8 versus 8.6 versus 9.4, P = 0.001), and along this line the area under the curve of LSM for the diagnosis of F3-F4 fibrosis was progressively reduced from lower to middle and further to higher CAP tertiles (0.915, 0.848-0.982; 0.830, 0.753-0.908; 0.806, 0.723-0.890). As a consequence, in subjects with F0-F2 fibrosis, the rates of false-positive LSM results for F3-F4 fibrosis increased according to CAP tertiles (7.2% in lower versus 16.6% in middle versus 18.1% in higher). Consistent with this, a decisional flowchart for predicting fibrosis was suggested by combining both LSM and CAP values.

CONCLUSIONS

In patients with NAFLD, CAP values should always be taken into account in order to avoid overestimations of liver fibrosis assessed by transient elastography. (Hepatology 2017;65:1145-1155).

How many times should we repeat measuring liver stiffness using shear wave elastography?: 5-repetition versus 10-repetition protocols

The purpose of this study is to evaluate whether a 5-repetition liver stiffness (LS) measurement as the standard protocol of shear wave elastography (SWE) is comparable to a conventional 10-repetition measurement protocol and to identify factors that influence the reliability of the 5-repetition protocol. A total of 346 patients (mean, 48.0years; range, 15-81years, M:F=192:154) who underwent SWE were enrolled. The median, first quartile, third quartile, and interquartile range divided by the median (IQR/M) of LS measurement were calculated and compared between 5-repetition and 10-repetition protocols. Subgroup analyses were also performed to identify factors associated with measurement reliability. The overall mean LS from the 10-repetition protocol was 7.97kPa, which was not significantly different from the mean LS of the 5-repetition protocol (7.91kPa; p=0.192). However, the third quartile and IQR/M values of the two groups were significantly different from each other (p=0.003 and <0.001). Subgroup analysis revealed that the 5-repetition results were significantly different from the 10-repetition results in the fatty liver and high LS subgroups. Therefore, the 5-repetition SWE measurement protocol can replace the conventional 10-repetition protocol, with the exception of patients with fatty liver disease or an LS value higher than 10kPa.

Shear Wave Elastography of Focal Liver Lesion: Intraobserver Reproducibility and Elasticity Characterization

PURPOSE

The aim of the study was to evaluate the intraobserver reproducibility and to determine the elasticity characteristics of focal liver lesions (FLLs) by shear wave elastography (SWE).

METHODS

One hundred thirty-six FLLs in 118 patients were examined with SWE for quantitative and qualitative assessment of stiffness. Three SWE images were obtained for each lesion and liver parenchyma by 1 radiologist. Intraobserver reproducibility was assessed by intraclass correlation coefficients (ICCs). Patient and lesion factors that can affect the reproducibility were evaluated. For characterization of the lesion elasticity, the difference in stiffness between the groups of lesions was evaluated.

RESULTS

The mean (SD) diameter and depth of the lesions were 3.98 (2.07) and 4.4 (1.59) cm, respectively. The ICC of intraobserver reproducibility was 0.763. Deep-seated lesions (≥6 cm; ICC, 0.621) showed significantly lower intraobserver reproducibility compared with superficial lesions (ICC, 0.793; P = 0.047). Stiffness values of malignant lesions (n = 85, 60.41 [47.81] kPa) were significantly higher than those of benign lesions (n = 51, 22.05 [17.24] kPa, P < 0.0001). Mean (SD) stiffness of hepatocellular carcinoma (45.72 [35.65] kPa) was significantly lower than that of metastasis (67.43 [43.39] kPa) and was significantly higher than benign FLLs (22.05 [17.24] kPa). However, mean (SD) lesion-parenchyma ratio of hepatocellular carcinoma (3.76 [4]) was not significantly different from that of benign FLLs (3.7 [3.77]).

CONCLUSIONS

Overall, intraobserver reproducibility of SWE in evaluation of FLLs was excellent, but it can be affected by lesion depth. In addition, SWE is helpful in elasticity characterization of FLLs.

Non-invasive assessment of liver fibrosis and prognosis

Over the past decade, several advances have been made in the non-invasive assessment of liver fibrosis. Both serum markers and imaging-based tissue elastography predict the presence of advanced fibrosis compared with liver biopsy. Serum markers may be indirect or direct markers of liver structure and function. Imaging-based techniques measure liver stiffness as a surrogate for fibrosis and include ultrasound and MRI-based methods. Most non-invasive techniques work well at identifying subjects at the extremes of fibrosis but may not accurately discern intermediate stages. In addition to being a diagnostic tool, elastography may have an evolving role in prognosis. Increasing stiffness is associated with higher rates of liver decompensation, need for transplantation, hepatocellular carcinoma, and death. There are special populations of patients where elastography may serve as a non-invasive method to impart useful clinical information, such as patients after liver transplantation, those with congenital heart disease and those being treated for chronic viral hepatitis. The role of non-invasive markers in accurately predicting the presence of fibrosis in obese patients needs to be further refined.

Magnetic Resonance Elastography: Measurement of Hepatic Stiffness Using Different Direct Inverse Problem Reconstruction Methods in Healthy Volunteers and Patients with Liver Disease

The purpose of this study was to compare the mean hepatic stiffness values obtained by the application of two different direct inverse problem reconstruction methods to magnetic resonance elastography (MRE). Thirteen healthy men (23.2±2.1 years) and 16 patients with liver diseases (78.9±4.3 years; 12 men and 4 women) were examined for this study using a 3.0 T-MRI. The healthy volunteers underwent three consecutive scans, two 70-Hz waveform and a 50-Hz waveform scans. On the other hand, the patients with liver disease underwent scanning using the 70-Hz waveform only. The MRE data for each subject was processed twice for calculation of the mean hepatic stiffness (Pa), once using the multiscale direct inversion (MSDI) and once using the multimodel direct inversion (MMDI). There were no significant differences in the mean stiffness values among the scans obtained with two 70-Hz and different waveforms. However, the mean stiffness values obtained with the MSDI technique (with mask: 2895.3±255.8 Pa, without mask: 2940.6±265.4 Pa) were larger than those obtained with the MMDI technique (with mask: 2614.0±242.1 Pa, without mask: 2699.2±273.5 Pa). The reproducibility of measurements obtained using the two techniques was high for both the healthy volunteers [intraclass correlation coefficients (ICCs): 0.840-0.953] and the patients (ICC: 0.830-0.995). These results suggest that knowledge of the characteristics of different direct inversion algorithms is important for longitudinal liver stiffness assessments such as the comparison of different scanners and evaluation of the response to fibrosis therapy.

Learning curve and intra/interobserver agreement of transient elastography in chronic hepatitis C patients with or without HIV co-infection

BACKGROUND AND OBJECTIVES

Liver stiffness measurement (LSM) by transient elastography has been validated as a noninvasive method to stage liver fibrosis. Few studies have evaluated the learning curve of this method and its reproducibility has led to controversy results. We aimed to evaluate the intra- and interobserver agreement of transient elastography as well as its learning curve for definition of an experimented operator.

METHODS

We retrospectively analyzed 922 examinations performed in 544 patients during a training program of transient elastography. Patients with chronic hepatitis C with or without HIV co-infection that had two examinations by the training operator (intraobserver analysis; n=125) or examination by both training and experimented operators (interobserver analysis; n=151) in the same day were included. LSM was converted to METAVIR score: <7.1 as F0F1, 7.1-9.4 as F2, 9.5-12.4, as F3 and >12.4 kPa as F4.

RESULTS

The overall intra- and interobserver intraclass correlation coefficient [ICC 95% CI] were 0.926 (0.901-0.951) and 0.912 (0.885-0.939), respectively. Measurements were correlated [Spearman's] in intra- [0.906, P<0.0001] and interobserver [0.907, P<0.0001] analysis. Reliability values [kappa (SE)] were k=0.74 (0.09) and k=0.85 (0.08) for fibrosis stages F ≥ 2 and k=0.77 (0.09) and k=0.75 (0.08) for cirrhosis in intra- and interobserver analysis, respectively. Agreement was improved when operator's experience was higher than 100 exams. However, it was observed discordance for fibrosis staging between examinations in a quarter of patients.

CONCLUSION

Although there was a considerable discrepancy on fibrosis staging between examinations and a small power, transient elastography had an acceptable reproducibility in our population. Performance of at least 100 examinations should be used to define an experimented operator.

Factors That Could Impact on Liver Fibrosis Staging by Transient Elastography

Transient elastography (TE) based on liver stiffness measurement (LSM) is one of the most validated noninvasive methods for liver fibrosis staging in patients with chronic liver diseases. This method is painless, has no potential complications, is rapid (<10 min), and can be performed at the patient's bedside. However, several points should be considered when interpreting TE results. This review aims to discuss the critical points that might influence liver stiffness and TE results. Spectrum bias and the impact of the prevalence of fibrosis stages should be taken into account when interpreting the studies that validated this method using liver biopsy as a gold-standard. LSM might be influenced by nonfasting status, flare of transaminases, heart failure, extrahepatic cholestasis, presence of steatosis, aetiology of liver disease, type and position of probe, and operator's experience. In addition, interobserver variability can impact on the management of patients with chronic liver diseases. TE should be performed by an experienced operator (>100 exams), in a 3-hour fasting status, and its results should be handled by specialist clinicians that are aware of the limitations of this method.

Controlled Attenuation Parameter and Liver Stiffness Measurements for Steatosis Assessment in the Liver Transplant of Brain Dead Donors

BACKGROUND

One of the main selection criteria of the quality of a liver graft is the degree of steatosis, which will determine the success of the transplantation. The aim of this study was to evaluate the ability of FibroScan and its related methods Controlled Attenuation Parameter and Liver Stiffness to assess objectively steatosis and fibrosis in livers from brain-dead donors to be potentially used for transplantation.

METHODS

Over a period of 10 months, 23 consecutive brain dead donors screened for liver procurement underwent a FibroScan and a liver biopsy.

RESULTS

The different predictive models of liver retrievability using liver biopsy as the gold standard have led to the following area under receiver operating characteristic curve: 76.6% (95% confidence intervals [95% CIs], 48.2%-100%) when based solely on controlled attenuation parameter, 75.0% (95% CIs, 34.3%-100%) when based solely on liver stiffness, and 96.7% (95% CIs, 88.7%-100%) when based on combined indices.

CONCLUSIONS

Our study suggests that a preoperative selection of brain-dead donors based on a combination of both Controlled Attenuation Parameter and Liver Stiffness obtained with FibroScan could result in a good preoperative prediction of the histological status and degree of steatosis of a potential liver graft.

Noninvasive assessment of alcoholic liver disease using unidimensional transient elastography (Fibroscan®)

Unidimensional transient elastography (TE) is a noninvasive technique, which has been increasingly used in the assessment of diffuse liver diseases. This paper focuses on reviewing the existing data on the use of TE in the diagnosis of fibrosis and in monitoring disease progression in alcoholic liver disease, on the factors that may influence the result of fibrosis prediction, and last but not least, on its potential use in assessing the steatosis degree. Therefore, this field is far from being exhausted and deserves more attention. Further studies are required, on large groups of biopsied patients, in order to find answers to all the remaining questions in this field.

WFUMB guidelines and recommendations for clinical use of ultrasound elastography: Part 3: liver

The World Federation for Ultrasound in Medicine and Biology (WFUMB) has produced these guidelines for the use of elastography techniques in liver disease. For each available technique, the reproducibility, results, and limitations are analyzed, and recommendations are given. Finally, recommendations based on the international literature and the findings of the WFUMB expert group are established as answers to common questions. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of liver diseases.

Significant variations in elastometry measurements made within short-term in patients with chronic liver diseases

BACKGROUND & AIMS

Transient elastometry is a noninvasive procedure used to measure fibrosis when patients are diagnosed with liver disease; it might be used to monitor changes over time. We investigated whether there are short-term variations in stiffness measurements that are not attributable to changes in fibrosis by studying patients with stable liver disease.

METHODS

We performed a retrospective analysis of 531 paired liver stiffness measurements made by Fibroscan when the study began (LSM1) and at follow-up (LSM2), more than 1 day and less than 1 year apart, from 432 stable (for body mass index, waist circumference, and alcohol consumption), untreated, immunocompetent patients with chronic liver disease (from January 2006 through March 2009). Variations between the first and follow-up measurements were expressed as absolute (LSM2-LSM1, kPa) or relative ([LSM2-LSM1]/LSM1*100) or as changes in fibrosis stage.

RESULTS

There was >20% variation in 49.7%, >30% in 34.3%, and >50% in 12.2% of paired measurements; this variation was constant across the spectrum of LSM1 values. The variations produced a 1-fibrosis stage difference in 31.5% of pairs and a ≥ 2-stage difference in 9.8% of pairs. Patients with LSM1 >7 kPa had increased probability of having a different stage of fibrosis at LSM2, compared with patients with LSM1 <7 kPa. Factors associated with variation included measurements made by 2 different operators or at least 1 non-senior operator, ratios of interquartile range:median values, significant fibrosis (≥ 7 kPa) at LSM1, baseline body mass index, or a 2-fold difference in level of alanine aminotransferase between measurements. When the analyses were restricted to measurements made by the same operator, the variation was slightly reduced; fibrosis stage differed between measurements for only 34.3% of cases.

CONCLUSIONS

Operator-related and patient-related factors produce significant variations in liver stiffness measurements made by transient elastometry, limiting its use in monitoring patients. These variations are unrelated to disease progression. The lowest levels of variation occur in measurements made in patients with no or early-stage fibrosis or by a single experienced operator.

Australian Liver Association (ALA) expert consensus recommendations for the use of transient elastography in chronic viral hepatitis

Since the introduction of Transient Elastography (TE) into Australia in 2008, non-invasive liver fibrosis assessments have integrated themselves into clinical hepatology. The Australian Liver Association (ALA) recognizes these technologies perform an important role in the assessment of chronic viral hepatitis B and C. However, in the setting of viral hepatitis and many other chronic liver diseases, there remains no consensus or guidelines regarding the performance, utility or reporting of TE. Accordingly, the ALA sought to produce an expert consensus statement for the use of TE in chronic viral hepatitis. The recommendations incorporated in this document are based upon a thorough literature review and draw on extensive clinical experience using TE. The initial draft was presented at Australian Gastroenterology Week (AGW) 2013. Through a collaborative process and expert external review a finalized document was presented at AGW 2014.

Principles and clinical application of ultrasound elastography for diffuse liver disease

Accurate assessment of the degree of liver fibrosis is important for estimating prognosis and deciding on an appropriate course of treatment for cases of chronic liver disease (CLD) with various etiologies. Because of the inherent limitations of liver biopsy, there is a great need for non-invasive and reliable tests that accurately estimate the degree of liver fibrosis. Ultrasound (US) elastography is considered a non-invasive, convenient, and precise technique to grade the degree of liver fibrosis by measuring liver stiffness. There are several commercial types of US elastography currently in use, namely, transient elastography, acoustic radiation force impulse imaging, supersonic shear-wave imaging, and real-time tissue elastography. Although the low reproducibility of measurements derived from operator-dependent performance remains a significant limitation of US elastography, this technique is nevertheless useful for diagnosing hepatic fibrosis in patients with CLD. Likewise, US elastography may also be used as a convenient surveillance method that can be performed by physicians at the patients' bedside to enable the estimation of the prognosis of patients with fatal complications related to CLD in a non-invasive manner.

Usefulness of transient elastography for noninvasive and reliable estimation of right-sided filling pressure in heart failure

Accurate noninvasive assessment of right atrial pressure (RAP) is important for volume management in patients with heart failure (HF). Transient elastography is a noninvasive and reliable method to assess liver stiffness (LS). We investigated the value of LS for evaluation of RAP in patients with HF without structural liver disease. We measured LS using transient elastography (Fibroscan) in 31 patients undergoing right-sided cardiac catheterization (test group). The relation between LS and RAP found in the test group was used to derive the best-fit model to predict RAP. The applicability of the model was then tested in a validation group of 49 additional patients. There was an excellent correlation between LS and RAP in the test group (r = 0.95, p <0.0001; RAP = -5.8 + 6.7 × ln [LS]). Natural log transformation (ln) of LS provided the regression equation to predict RAP. When the equation model derived from the test group was applied to the validation group, predicted RAP correlated excellently with actual RAP (r = 0.90, p <0.0001). The receiver operating characteristic curve analyses in the test group showed that LS favorably compared with echocardiography for detecting RAP >10 mm Hg (area under the curve 0.958 vs 0.800, respectively, p = 0.047). In the validation group, LS with a cut-off value of 10.6 kPa for identifying RAP >10 mm Hg had a higher sensitivity and accuracy (p = 0.046 and p = 0.049, respectively) than echocardiography. In conclusion, LS may offer an accurate noninvasive diagnostic method to assess RAP in patients with HF.

Operator training requirements and diagnostic accuracy of Fibroscan in routine clinical practice

BACKGROUND

Fibroscan is a quick, non-invasive technique used to measure liver stiffness (kPa), which correlates with fibrosis. To achieve a valid liver stiffness evaluation (LSE) the operator must obtain all the following three criteria: (1) ≥10 successful liver stiffness measurements; (2) IQR/median ratio <0.30 and (3) ≥60% measurement success rate.

OBJECTIVES

To assess the operator training requirements and the importance of adhering to the LSE validity criteria in routine clinical practice.

METHODS

We retrospectively analysed the LSE validity rates of 2311 Fibroscans performed (1 August 2008 to 31 July 2011) in our tertiary liver outpatients department at the University Hospital Birmingham, UK. The diagnostic accuracy of Fibroscan was assessed in 153 patients, by comparing LSE (valid and invalid) with the modified Ishak fibrosis stage on liver biopsy.

RESULTS

Learning curve analysis highlighted that the greatest improvement in validity of LSE rates occurs in the operator's first 10 Fibroscans, reaching 64.7% validity by the 50th Fibroscan. The correlation between LSE and the fibrosis stage on liver biopsy was superior in patients with a valid LSE (n=97) compared with those with an invalid LSE (n=56) (rs 0.577 vs 0.259; p=0.022). Area under receiving operating characteristics for significant fibrosis was greater when LSE was valid (0.83 vs 0.66; p=0.048). Using an LSE cut-off of 8 kPa, the negative predictive value of valid LSE was superior to invalid LSE for the detection of significant (84% vs 71%) and advanced fibrosis (100% vs 93%).

CONCLUSIONS

Fibroscan requires minimal operator training (≥10 observed on patients), and when a valid LSE is obtained, it is an accurate tool for excluding advanced liver fibrosis. To ensure the diagnostic accuracy of Fibroscan it is essential that the recommended LSE validity criteria are adhered to in routine clinical practice.