Early detection of nonalcoholic steatohepatitis in patients with nonalcoholic fatty liver disease by using MR elastography

Longitudinal Magnetic Resonance Imaging with ROS-Responsive Bilirubin Nanoparticles Enables Monitoring of Nonalcoholic Steatohepatitis Progression to Cirrhosis

Despite the vital importance of monitoring the progression of nonalcoholic fatty liver disease (NAFLD) and its progressive form, nonalcoholic steatohepatitis (NASH), an efficient imaging modality that is readily available at hospitals is currently lacking. Here, a new magnetic-resonance-imaging (MRI)-based imaging modality is presented that allows for efficient and longitudinal monitoring of NAFLD and NASH progression. The imaging modality uses manganese-ion (Mn2+)-chelated bilirubin nanoparticles (Mn@BRNPs) as a reactive-oxygen-species (ROS)-responsive MRI imaging probe. Longitudinal T1-weighted MR imaging of NASH model mice is performed after injecting Mn@BRNPs intravenously. The MR signal enhancement in the liver relative to muscle gradually increases up to 8 weeks of NASH progression, but decreases significantly as NASH progresses to the cirrhosis-like stage at weeks 10 and 12. A new dual input pseudo-three-compartment model is developed to provide information on NASH stage with a single MRI scan. It is also demonstrated that the ROS-responsive Mn@BRNPs can be used to monitor the efficacy of potential anti-NASH drugs with conventional MRI. The findings suggest that the ROS-responsive Mn@BRNPs have the potential to serve as an efficient MRI contrast for monitoring NASH progression and its transition to the cirrhosis-like stage.

Whole-body magnetic resonance imaging at 0.05 Tesla

Despite a half-century of advancements, global magnetic resonance imaging (MRI) accessibility remains limited and uneven, hindering its full potential in health care. Initially, MRI development focused on low fields around 0.05 Tesla, but progress halted after the introduction of the 1.5 Tesla whole-body superconducting scanner in 1983. Using a permanent 0.05 Tesla magnet and deep learning for electromagnetic interference elimination, we developed a whole-body scanner that operates using a standard wall power outlet and without radiofrequency and magnetic shielding. We demonstrated its wide-ranging applicability for imaging various anatomical structures. Furthermore, we developed three-dimensional deep learning reconstruction to boost image quality by harnessing extensive high-field MRI data. These advances pave the way for affordable deep learning-powered ultra-low-field MRI scanners, addressing unmet clinical needs in diverse health care settings worldwide.

The Effect of Steatosis on Shear-Wave Velocity and Viscoelastic Properties Related to Liver Fibrosis Progression in Rat Models

OBJECTIVE

Hepatic fibrosis has recently been evaluated using ultrasonography or magnetic resonance elastography. Although the shear wave velocity (SWV) obtained using point shear wave elastography (pSWE) provides a valuable measure of fibrosis, underlying steatosis may affect its measurement.

METHODS

Using hepatic fibrosis samples, this study evaluated the effect of steatosis on the shear wave velocity of pSWE (Vs) and viscoelastic properties (assessed by dynamic mechanical analysis) of rat liver. Fifty rats with various grades of steatosis and fibrosis underwent open abdominal in vivo Vs measurements using a commercial ultrasound scanner. The mechanical properties of hepatic tissue were also characterized under ex vivo conditions using dynamic mechanical analysis and the Zener model of viscoelasticity.

RESULTS

Fibrosis and steatosis progression influenced Vs and elasticity. The SWV computed using the Zener model and Vs showed a substantial correlation (r > 0.8). Fibrosis progression increased SWV. Steatosis was also related to SWV. Steatosis progression obscured the SWV change associated with fibrosis progression.

CONCLUSION

We conclude that steatosis progression affects the evaluation of fibrosis progression. This finding could aid discrimination of non-alcoholic steatohepatitis from non-alcoholic fatty liver disease using SWV.

Magnetic resonance elastography for the prediction of hepatocellular carcinoma in chronic hepatitis B

Background and Aim

Magnetic resonance elastography (MRE) is used for the evaluation of liver fibrosis; however, it remains unclear whether MRE-based liver stiffness is associated with hepatocellular carcinoma (HCC) development, particularly in patients with chronic hepatitis B.

Methods

A total of 504 patients with chronic hepatitis B receiving MRE were enrolled. The primary endpoint was the association between MRE-based liver stiffness and HCC.

Results

In a cross-sectional analysis at the time of MRE measurement, the median (interquartile range) liver stiffness values in patients with presence or history of HCC and those without HCC were 3.68 (2.89-4.96) and 2.60 (2.22-3.45) kPa, respectively, and liver stiffness was significantly higher in patients with presence or history of HCC than in those without HCC (P < 0.001). In a longitudinal analysis of patients without HCC, the 1-, 3-, and 5-year cumulative incidence of HCC in patients with liver stiffness ≥3.6 kPa and those with liver stiffness <3.6 kPa were 3.8%, 7.0%, and 22.9%, and 0%, 0.9%, and 1.5%, respectively (P < 0.001). In the multivariable analysis, MRE-based liver stiffness (per 1 kPa) or liver stiffness ≥3.6 kPa was an independent factor for HCC development with an adjusted hazard ratio (aHR) of 1.61 (95% confidence interval [CI], 1.3-2.0) or aHR of 8.22 (95% CI, 2.1-31).

Conclusion

MRE-based liver stiffness is associated with HCC risk in patients with chronic hepatitis B and may be used for the early prediction of HCC development and determination of indications for treatment.

Interpretation, Reporting, and Clinical Applications of Liver MR Elastography

Chronic liver disease is highly prevalent and often leads to fibrosis or cirrhosis and complications such as liver failure and hepatocellular carcinoma. The diagnosis and staging of liver fibrosis is crucial to determine management and mitigate complications. Liver biopsy for histologic assessment has limitations such as sampling bias and high interreader variability that reduce precision, which is particularly challenging in longitudinal monitoring. MR elastography (MRE) is considered the most accurate noninvasive technique for diagnosing and staging liver fibrosis. In MRE, low-frequency vibrations are applied to the abdomen, and the propagation of shear waves through the liver is analyzed to measure liver stiffness, a biomarker for the detection and staging of liver fibrosis. As MRE has become more widely used in clinical care and research, different contexts of use have emerged. This review focuses on the latest developments in the use of MRE for the assessment of liver fibrosis; provides guidance for image acquisition and interpretation; summarizes diagnostic performance, along with thresholds for diagnosis and staging of liver fibrosis; discusses current and emerging clinical applications; and describes the latest technical developments.

Changes in nonalcoholic fatty liver disease and M2BPGi due to lifestyle intervention in primary healthcare

BACKGROUND

A healthy lifestyle is the most important method for managing nonalcoholic fatty liver disease (NAFLD). Mac-2-binding protein glycosylated isomer (M2BPGi) has been suggested as a biomarker for NAFLD. This study aimed to determine the efficacy of personalized lifestyle interventions on NAFLD remission.

METHODS

This single-arm intervention study recruited participants with NAFLD who underwent health checkups at seven health-promotion centers in five South Korean cities. Fatty liver diagnosis was based on ultrasonography (US). The 109 individuals were recruited for personalized lifestyle interventions of hypocaloric diets and exercise. The participants attended the lifestyle intervention programs once per month for the first 3 months, and once every 3 months for the subsequent 6 months. In addition to sessions through center visits, phone-based intervention and self-monitoring at 4-, 5-, 7-, and 8-month were provided during the 9-month intervention period. And phone-based self-monitoring were also provided monthly during the 3-month follow-up period. The primary outcome was NAFLD remission at month 12 as measured on US and magnetic resonance elastography. The secondary outcomes were the changes in metabolic factors and M2BPGi.

RESULTS

The 108 individuals (62 males and 46 females; age 51.1±12.4 years, mean±standard deviation) were finally analyzed after the 12month intervention. Body mass index, waist circumference (WC), blood pressure, blood lipids (total cholesterol, triglycerides, and HDL-C), and fasting blood sugar levels were improved relative to baseline (all P<0.05). Fatty liver at or above the moderate grade according to US was decreased at month 12 relative to baseline (67.6% vs 50.9%) (P = 0.002). M2BPGi levels decreased during the 12-month study period (P<0.001). M2BPGi levels were moderately correlated with hepatic fat fraction by magnetic resonance imaging (r = 0.33, P = 0.05). WC (OR = 0.82, 95% CI = 0.67-1.00, P = 0.05) and HDL-C (OR = 1.17, 95% CI = 1.03-1.32, P = 0.014) were associated with remission of fatty liver in the multivariate analysis.

CONCLUSION

The personalized lifestyle intervention was effective in improving fatty liver and metabolic factors, but not hepatic stiffness, in NAFLD.

TRIAL REGISTRATION

ICTRP, cris.nih.go.kr (KCT0006380).

Non-Invasive Assessment of Liver Fibrosis in Hepatitis B Patients

The aim of this review is to provide updated information on the clinical use of non-invasive serum and imaging-based tests for fibrosis assessment in chronic hepatitis B (CHB) virus infection. In recent years, non-invasive tests (NIT) have been increasingly used to determine eligibility for treatment. Liver biopsy is still considered the gold standard for assessing inflammatory activity and fibrosis staging, but it is an invasive procedure with inherent limitations. Simple serum markers such as APRI and FIB-4 are limited by indeterminate results but remain useful initial tests for fibrosis severity if imaging elastography is not available. Point-of-care US-based elastography techniques, such as vibration-controlled transient elastography or 2D shear wave elastography, are increasingly available and have better accuracy than simple serum tests for advanced fibrosis or cirrhosis, although stiffness cut-offs are variable based on E-antigen status and inflammatory activity. Current NITs have poor diagnostic performance for following changes in fibrosis with antiviral therapy. However, NITs may have greater clinical utility for determining prognosis in patients with CHB that have advanced disease, especially for the development of hepatocellular carcinoma and/or liver decompensation. Algorithms combining serum and imaging NITs appear promising for advanced fibrosis and prognostic risk stratification.

Liver Magnetic Resonance Elastography: Focus on Methodology, Technique, and Feasibility

Magnetic resonance elastography (MRE) is an imaging technique that combines low-frequency mechanical vibrations with magnetic resonance imaging to create visual maps and quantify liver parenchyma stiffness. As in recent years, diffuse liver diseases have become highly prevalent worldwide and could lead to a chronic condition with different stages of fibrosis. There is a strong necessity for a non-invasive, highly accurate, and standardised quantitative assessment to evaluate and manage patients with different stages of fibrosis from diagnosis to follow-up, as the actual reference standard for the diagnosis and staging of liver fibrosis is biopsy, an invasive method with possible peri-procedural complications and sampling errors. MRE could quantitatively evaluate liver stiffness, as it is a rapid and repeatable method with high specificity and sensitivity. MRE is based on the propagation of mechanical shear waves through the liver tissue that are directly proportional to the organ's stiffness, expressed in kilopascals (kPa). To obtain a valid assessment of the real hepatic stiffness values, it is mandatory to obtain a high-quality examination. To understand the pearls and pitfalls of MRE, in this review, we describe our experience after one year of performing MRE from indications and patient preparation to acquisition, quality control, and image analysis.

Enhanced non-alcoholic fatty liver detection: Computed tomography scan image analysis and noise reduction with morphological dilation

Non-alcoholic fatty liver disease (NAFLD) is characterized by accumulation of fat in the liver cells caused by means other than alcohol consumption. It is one of the most common chronic liver diseases worldwide and can lead to severe conditions, such as cirrhosis and liver cancer. NAFLD is often associated with other metabolic disorders, such as obesity and diabetes, and is closely related to lifestyle factors, such as diet and physical activity [1]. The diagnosis as well as management of NAFLD are complex and involve a multidisciplinary approach. The available treatment options include lifestyle modifications, pharmacological interventions, and in severe cases, liver transplantation. The increasing prevalence of NAFLD highlights the urgent requirement of effective prevention and management strategies. This disease is a growing health concern in India, given the rise in the incidence of obesity and diabetes. According to a study published in the Journal of Clinical and Experimental Hepatology in 2020, the prevalence of NAFLD in India is estimated to be between 9% and 32%. In accordance with the research population and diagnostic criteria employed, a study published in the Indian Journal of Gastroenterology in 2019 found that the prevalence of NAFLD in India ranged from 9.6% to 32.3% [2]. The same study also revealed that the prevalence of non-alcoholic steatohepatitis (NASH), a highly severe form of NAFLD, ranged from 1.5% to 8.4%. These statistics highlight the need for increased awareness and preventive measures to manage the growing burden of NAFLD in India.

Optimization of the Tracking Beam Sequence in Harmonic Motion Imaging

Harmonic motion imaging (HMI) is an ultrasound elastography technique that estimates the viscoelastic properties of tissues by inducing localized oscillatory motion using focused ultrasound (FUS). The resulting displacement, assumed to be inversely proportional to the tissue local stiffness, is estimated using an imaging array based on RF speckle tracking. In conventional HMI, this is accomplished with plane-wave (PW) imaging, which inherently suffers from low lateral resolution. Coherent PW compounding (PWC) leverages spatial and temporal resolution using synthetic focusing in transmit. In this study, we introduced focused imaging with parallel tracking in HMI and compared parallel tracking of various transmit F-numbers (F/2.6, 3, 4, and 5) qualitatively and quantitatively with PW and PWC imaging at various compounded angle ranges (6°, 12°, and 18°). An in silico model of a 56-kPa spherical inclusion (diameter: 3.6 mm) embedded in a 5.3-kPa background and a 5.3-kPa elastic phantom with cylindrical inclusions (Young's moduli: 22-56 kPa, diameters: 2.0-8.6 mm) were imaged to assess different tracking beam sequences. Speckle biasing in displacement estimation associated with parallel tracking was also investigated and concluded to be negligible in HMI. Parallel tracking in receive (Rx) resulted in 2%-7% and 8%-12% increase compared to PW imaging ( ) in HMI contrast and contrast-to-noise ratio in silico and phantoms. Focused imaging with parallel tracking in Rx was concluded to be most robust among PW and PWC imaging for displacement estimation, and its preclinical feasibility was demonstrated in postsurgical human cancerous breast tissue specimens and in vivo murine models of breast cancer.

ACR Appropriateness Criteria® Abnormal Liver Function Tests

Liver function tests are commonly obtained in symptomatic and asymptomatic patients. Various overlapping lab patterns can be seen due to derangement of hepatocytes and bile ducts function. Imaging tests are pursued to identify underlying etiology and guide management based on the lab results. Liver function tests may reveal mild, moderate, or severe hepatocellular predominance and can be seen in alcoholic and nonalcoholic liver disease, acute hepatitis, and acute liver injury due to other causes. Cholestatic pattern with elevated alkaline phosphatase with or without elevated γ-glutamyl transpeptidase can be seen with various causes of obstructive biliopathy. Acute or subacute cholestasis with conjugated or unconjugated hyperbilirubinemia can be seen due to prehepatic, intrahepatic, or posthepatic causes. We discuss the initial and complementary imaging modalities to be used in clinical scenarios presenting with abnormal liver function tests. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

M-PAST score is better than MAST score for the diagnosis of active fibrotic nonalcoholic steatohepatitis

BACKGROUND

Clinical trials enroll patients with active fibrotic nonalcoholic steatohepatitis (NASH) (nonalcoholic fatty liver disease [NAFLD] activity score ≥ 4) and significant fibrosis (F ≥ 2); however, screening failure rates are high following biopsy. We developed new scores to identify active fibrotic NASH using FibroScan and magnetic resonance imaging (MRI).

METHODS

We undertook prospective primary (n = 176), retrospective validation (n = 169), and University of California San Diego (UCSD; n = 234) studies of liver biopsy-proven NAFLD. Liver stiffness measurement (LSM) using FibroScan or magnetic resonance elastography (MRE), controlled attenuation parameter (CAP), or proton density fat fraction (PDFF), and aspartate aminotransferase (AST) were combined to develop a two-step strategy-FibroScan-based LSM followed by CAP with AST (F-CAST) and MRE-based LSM followed by PDFF with AST (M-PAST)-and compared with FibroScan-AST (FAST) and MRI-AST (MAST) for diagnosing active fibrotic NASH. Each model was categorized using rule-in and rule-out criteria.

RESULTS

Areas under receiver operating characteristic curves (AUROCs) of F-CAST (0.826) and M-PAST (0.832) were significantly higher than those of FAST (0.744, p = 0.004) and MAST (0.710, p < 0.001). Following the rule-in criteria, positive predictive values of F-CAST (81.8%) and M-PAST (81.8%) were higher than those of FAST (73.5%) and MAST (70.0%). Following the rule-out criteria, negative predictive values of F-CAST (90.5%) and M-PAST (90.9%) were higher than those of FAST (84.0%) and MAST (73.9%). In the validation and UCSD cohorts, AUROCs did not differ significantly between F-CAST and FAST, but M-PAST had a higher diagnostic performance than MAST.

CONCLUSIONS

The two-step strategy, especially M-PAST, showed reliability of rule-in/-out for active fibrotic NASH, with better predictive performance compared with MAST. This study is registered with ClinicalTrials.gov (number, UMIN000012757).

An individual patient data meta-analysis to determine cut-offs for and confounders of NAFLD-fibrosis staging with magnetic resonance elastography

BACKGROUND & AIMS

We conducted an individual patient data meta-analysis to establish stiffness cut-off values for magnetic resonance elastography (MRE) in staging liver fibrosis and to assess potential confounding factors.

METHODS

A systematic review of the literature identified studies reporting MRE data in patients with NAFLD. Data were obtained from the corresponding authors. The pooled diagnostic cut-off value for the various fibrosis stages was determined in a two-stage meta-analysis. Multilevel modelling methods were used to analyse potential confounding factors influencing the diagnostic accuracy of MRE in staging liver fibrosis.

RESULTS

Eight independent cohorts comprising 798 patients were included in the meta-analysis. The area under the receiver operating characteristic curve (AUROC) for MRE in detecting significant fibrosis was 0.92 (sensitivity, 79%; specificity, 89%). For advanced fibrosis, the AUROC was 0.92 (sensitivity, 87%; specificity, 88%). For cirrhosis, the AUROC was 0.94 (sensitivity, 88%, specificity, 89%). Cut-offs were defined to explore concordance between MRE and histopathology: ≥F2, 3.14 kPa (pretest probability, 39.4%); ≥F3, 3.53 kPa (pretest probability, 24.1%); and F4, 4.45 kPa (pretest probability, 8.7%). In generalized linear mixed model analysis, histological steatohepatitis with higher inflammatory activity (odds ratio 2.448, 95% CI 1.180-5.079, p <0.05) and high gamma-glutamyl transferase (GGT) concentration (>120U/L) (odds ratio 3.388, 95% CI 1.577-7.278, p <0.01] were significantly associated with elevated liver stiffness, and thus affecting accuracy in staging early fibrosis (F0-F1). Steatosis, as measured by magnetic resonance imaging proton density fat fraction, and body mass index(BMI) were not confounders.

CONCLUSIONS

MRE has excellent diagnostic performance for significant, advanced fibrosis and cirrhosis in patients with NAFLD. Elevated inflammatory activity and GGT level may lead to overestimation of early liver fibrosis, but anthropometric measures such as BMI or the degree of steatosis do not.

IMPACT AND IMPLICATIONS

This individual patient data meta-analysis of eight international cohorts, including 798 patients, demonstrated that MRE achieves excellent diagnostic accuracy for significant, advanced fibrosis and cirrhosis in patients with NAFLD. Cut-off values (significant fibrosis, 3.14 kPa; advanced fibrosis, 3.53 kPa; and cirrhosis, 4.45 kPa) were established. Elevated inflammatory activity and gamma-glutamyltransferase level may affect the diagnostic accuracy of MRE, leading to overestimation of liver fibrosis in early stages. We observed no impact of diabetes, obesity, or any other metabolic disorder on the diagnostic accuracy of MRE.

Multiparametric Magnetic Resonance Imaging and Magnetic Resonance Elastography to Evaluate the Early Effects of Bariatric Surgery on Nonalcoholic Fatty Liver Disease

Background

Bariatric surgery is the most effective treatment for morbid obesity and reduces the severity of nonalcoholic fatty liver disease (NAFLD) in the long term. Less is known about the effects of bariatric surgery on liver fat, inflammation, and fibrosis during the early stages following bariatric surgery.

Aims

This exploratory study utilises advanced imaging methods to investigate NAFLD and fibrosis changes during the early metabolic transitional period following bariatric surgery.

Methods

Nine participants with morbid obesity underwent sleeve gastrectomy. Multiparametric MRI (mpMRI) and magnetic resonance elastography (MRE) were performed at baseline, during the immediate (1 month), and late (6 months) postsurgery period. Liver fat was measured using proton density fat fraction (PDFF), disease activity using iron-correct T1 (cT1), and liver stiffness using MRE. Repeated measured ANOVA was used to assess longitudinal changes and Dunnett's method for multiple comparisons.

Results

All participants (Age 45.1 ± 9.0 years, BMI 39.7 ± 5.3 kg/m²) had elevated hepatic steatosis at baseline (PDFF >5%). In the immediate postsurgery period, PDFF decreased significantly from 14.1 ± 7.4% to 8.9 ± 4.4% (p = 0.016) and cT1 from 826.9 ± 80.6 ms to 768.4 ± 50.9 ms (p = 0.047). These improvements continued to the later postsurgery period. Bariatric surgery did not reduce liver stiffness measurements.

Conclusion

Our findings support using MRI as a noninvasive tool to monitor NAFLD in patient with morbid obesity during the early stages following bariatric surgery.

Ferroptosis as an emerging therapeutic target in liver diseases

Ferroptosis is an iron-dependently nonapoptotic cell death characterized by excessive accumulation of lipid peroxides and cellular iron metabolism disturbances. Impaired iron homeostasis and dysregulation of metabolic pathways are contributors to ferroptosis. As a major metabolic hub, the liver synthesizes and transports plasma proteins and endogenous fatty acids. Also, it acts as the primary location of iron storage for hepcidin generation and secretion. To date, although the intricate correlation between ferroptosis and liver disorders needs to be better defined, there is no doubt that ferroptosis participates in the pathogenesis of liver diseases. Accordingly, pharmacological induction and inhibition of ferroptosis show significant potential for the treatment of hepatic disorders involved in lipid peroxidation. In this review, we outline the prominent features, molecular mechanisms, and modulatory networks of ferroptosis and its physiopathologic functions in the progression of liver diseases. Further, this review summarizes the underlying mechanisms by which ferroptosis inducers and inhibitors ameliorate liver diseases. It is noteworthy that natural active ingredients show efficacy in preclinical liver disease models by regulating ferroptosis. Finally, we analyze crucial concepts and urgent issues concerning ferroptosis as a novel therapeutic target in the diagnosis and therapy of liver diseases.

How to Identify Advanced Nonalcoholic Fatty Liver Disease in the Primary Care Setting

Nonalcoholic fatty liver disease (NAFLD) affects 30 to 40% of the population globally and is increasingly considered the most common liver disease. Patients with type 2 diabetes, obesity, and cardiovascular diseases are at especially increased risk for NAFLD. Although most patients with NAFLD do not have progressive liver disease, some patients progress to cirrhosis, liver cancer, and liver mortality. Given the sheer number of patients with NAFLD, the burden of disease is enormous. Despite this large and increasing burden, identification of NAFLD patients at risk for progressive liver disease in the primary care and diabetology practice settings remains highly suboptimal. In this review, our aim is to summarize a stepwise approach to risk stratify patients with NAFLD which should help practitioners in their management of patients with NAFLD.

Non-invasive multispectral optoacoustic tomography resolves intrahepatic lipids in patients with hepatic steatosis

Hepatic steatosis is characterized by intrahepatic lipid accumulation and may lead to irreversible liver damage if untreated. Here, we investigate whether multispectral optoacoustic tomography (MSOT) can offer label-free detection of liver lipid content to enable non-invasive characterization of hepatic steatosis by analyzing the spectral region around 930 nm, where lipids characteristically absorb. In a pilot study, we apply MSOT to measure liver and surrounding tissues in five patients with liver steatosis and five healthy volunteers, revealing significantly higher absorptions at 930 nm in the patients, while no significant difference was observed in the subcutaneous adipose tissue of the two groups. We further corroborated the human observations with corresponding MSOT measurements in high fat diet (HFD) - and regular chow diet (CD)-fed mice. This study introduces MSOT as a potential non-invasive and portable technique for detecting/monitoring hepatic steatosis in clinical settings, providing justification for larger studies.

Artificial Intelligence in NAFLD: Will Liver Biopsy Still Be Necessary in the Future?

As the advanced form of nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH) will significantly increase the risks of liver fibrosis, cirrhosis, and HCC. However, there is no non-invasive method to distinguish NASH from NAFLD so far. Additionally, liver biopsy remains the gold standard to diagnose NASH, which is not appropriate for routine screening. Recently, artificial intelligence (AI) is under rapid development in many aspects of medicine. Additionally, the application of AI in clinical information may have the potential to diagnose NASH non-invasively. This review summarizes the latest research using AI, specifically machine learning, to facilitate the diagnosis, prognosis, and monitoring of NAFLD. Additionally, according to our prior results, this work proposes future development in this area.

Updates on Quantitative MRI of Diffuse Liver Disease: A Narrative Review

Diffuse liver diseases are highly prevalent conditions around the world, including pathological liver changes that occur when hepatocytes are damaged and liver function declines, often leading to a chronic condition. In the last years, Magnetic Resonance Imaging (MRI) is reaching an important role in the study of diffuse liver diseases moving from qualitative to quantitative assessment of liver parenchyma. In fact, this can allow noninvasive accurate and standardized assessment of diffuse liver diseases and can represent a concrete alternative to biopsy which represents the current reference standard. MRI approach already tested for other pathologies include diffusion-weighted imaging (DWI) and radiomics, able to quantify different aspects of diffuse liver disease. New emerging MRI quantitative methods include MR elastography (MRE) for the quantification of the hepatic stiffness in cirrhotic patients, dedicated gradient multiecho sequences for the assessment of hepatic fat storage, and iron overload. Thus, the aim of this review is to give an overview of the technical principles and clinical application of new quantitative MRI techniques for the evaluation of diffuse liver disease.

Chronic kidney disease in nonalcoholic fatty liver disease at primary healthcare centers in Korea

BACKGROUND

The prevalence rates of nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) are expected to increase with the rising trends in diabetes and obesity associated with aging populations. Considering the impacts of coexistent NAFLD and CKD on morbidity and mortality rates, screening strategies for groups at high-risk of CKD are needed in community-dwelling individuals with NAFLD. The aims of this study were to determine the prevalence and distribution of CKD in NAFLD, as well as the risk factors for CKD and the correlation with liver fibrosis in asymptomatic individuals with NAFLD at primary healthcare centers in Korea.

METHODS

This retrospective cross-sectional study used data from 13 health-promotion centers in 10 Korean cities. Liver steatosis and stiffness were assessed using ultrasonography and magnetic resonance elastography (MRE), respectively. CKD was defined as an estimated glomerular filtration rate of <60 mL/min/1.73m2, and urine albumin-to-creatinine ratio or proteinuria. CKD was categorized into four stages: no CKD, mild, moderate, and severe. Comparisons according to the CKD stages in NAFLD were performed using Student's t-test or the chi-square test. Multivariable logistic regression analyses were performed to identify the risk factors for CKD and the correlation with liver fibrosis in NAFLD.

RESULTS

The prevalence of CKD was 12.4% in NAFLD. Albuminuria (16.2%) and proteinuria (8.0%) were more prevalent in NAFLD. NAFLD (odd ratio = 1.27, 95% CI = 1.09-1.48, P = 0.003) was independently associated with CKD of at least mild stage. However, there was no significant association between CKD of at least moderate stage and NAFLD after adjusting for age and a metabolically unhealthy status. CKD was associated with significant liver fibrosis as measured by MRE in NAFLD.

CONCLUSION

The presence of NAFLD and liver fibrosis were independent risk factors for CKD, but NAFLD was not an independent risk factor for the later stages of CKD.

Radiomics Analysis of Magnetic Resonance Proton Density Fat Fraction for the Diagnosis of Hepatic Steatosis in Patients With Suspected Non-Alcoholic Fatty Liver Disease

BACKGROUND

This study aimed to assess the diagnostic feasibility of radiomics analysis based on magnetic resonance (MR)-proton density fat fraction (PDFF) for grading hepatic steatosis in patients with suspected non-alcoholic fatty liver disease (NAFLD).

METHODS

This retrospective study included 106 patients with suspected NAFLD who underwent a hepatic parenchymal biopsy. MR-PDFF and MR spectroscopy were performed on all patients using a 3.0-T scanner. Following whole-volume segmentation of the MR-PDFF images, 833 radiomic features were analyzed using a commercial program. Radiologic features were analyzed, including median and mean values of the multiple regions of interest and variable clinical features. A random forest regressor was used to extract the important radiomic, radiologic, and clinical features. The model was trained using 20 repeated 10-fold cross-validations to classify the NAFLD steatosis grade. The area under the receiver operating characteristic curve (AUROC) was evaluated using a classifier to diagnose steatosis grades.

RESULTS

The levels of pathological hepatic steatosis were classified as low-grade steatosis (grade, 0-1; n = 82) and high-grade steatosis (grade, 2-3; n = 24). Fifteen important features were extracted from the radiomic analysis, with the three most important being wavelet-LLL neighboring gray tone difference matrix coarseness, original first-order mean, and 90th percentile. The MR spectroscopy mean value was extracted as a more important feature than the MR-PDFF mean or median in radiologic measures. Alanine aminotransferase has been identified as the most important clinical feature. The AUROC of the classifier using radiomics was comparable to that of radiologic measures (0.94 ± 0.09 and 0.96 ± 0.08, respectively).

CONCLUSION

MR-PDFF-derived radiomics may provide a comparable alternative for grading hepatic steatosis in patients with suspected NAFLD.

Staging Liver Fibrosis by Fibroblast Activation Protein Inhibitor PET in a Human-Sized Swine Model

Current methods of staging liver fibrosis have notable limitations. We investigated the utility of PET in staging liver fibrosis by correlating liver uptake of ⁶⁸Ga-labeled fibroblast activation protein inhibitor (FAPI) with histology in a human-sized swine model. Methods: Five pigs underwent baseline ⁶⁸Ga-FAPI-46 (⁶⁸Ga-FAPI) PET/MRI and liver biopsy, followed by liver parenchymal embolization, 8 wk of oral alcohol intake, endpoint ⁶⁸Ga-FAPI PET/MRI, and necropsy. Regions of interest were drawn on baseline and endpoint PET images, and SUV_mean was recorded. At the endpoint, liver sections corresponding to regions of interest were identified and cut out. Fibrosis was histologically evaluated using a modified METAVIR score for swine liver and quantitatively using collagen proportionate area (CPA). Box-and-whisker plots and linear regression were used to correlate SUV_mean with METAVIR score and CPA, respectively. Results: Liver ⁶⁸Ga-FAPI uptake strongly correlated with CPA (r = 0.89, P < 0.001). ⁶⁸Ga-FAPI uptake was significantly and progressively higher across F2 and F3/F4 fibrosis stages, with a respective median SUV_mean of 2.9 (interquartile range [IQR], 2.7-3.8) and 7.6 (IQR, 6.7-10.2) (P < 0.001). There was no significant difference between ⁶⁸Ga-FAPI uptake of baseline liver and endpoint liver sections staged as F0/F1, with a respective median SUV_mean of 1.7 (IQR, 1.3-2.0) and 1.7 (IQR, 1.5-1.8) (P = 0.338). Conclusion: The strong correlation between liver ⁶⁸Ga-FAPI uptake and the histologic stage of liver fibrosis suggests that ⁶⁸Ga-FAPI PET can play an impactful role in noninvasive staging of liver fibrosis, pending validation in patients.

Stratifying Non-alcoholic Steatohepatitis With the Non-invasive Ultrasound Markers Shear Wave Dispersion Slope and Shear Wave Velocity: An Animal Study

We evaluated the significance of the ultrasound (US) markers shear wave dispersion slope (SWDS) and shear wave velocity (SWV) for identification of non-alcoholic steatohepatitis (NASH) and high-risk NASH; the latter was defined as the presence of steatohepatitis, a non-alcoholic fatty liver disease activity score (NAS) ≥4 or a fibrosis stage ≥2. Thirty-six male Sprague-Dawley (SD) rats were assigned to two groups: the study (n = 30) and control (n = 6) groups. To initiate non-alcoholic steatohepatitis, study group rats were fed a diet deficient in methionine and choline. All rats were examined using ultrasonography to obtain the SWDS and SWV parameters of the liver at the same time points. Fatty liver pathological grades were determined after euthanasia; the livers were categorized in the normal (n = 6), NAFL (non-alcoholic fatty liver) (n = 10) and NASH (n = 20) subgroups based on the NAS scoring system. They were also categorized into subgroups F0 (n = 22), F1 (n = 3), F2 (n = 7) and F3 (n = 4) on the basis of the METAVIR (Meta-analysis of Histological Data in Viral Hepatitis) scoring system. Measurement differences between various grades were evaluated by analysis of variance (ANOVA) or the Mann-Whitney U-test. We used logistic regression to calculate a combination of the two parameters for combined assessment of parameters. The diagnostic value of SWDS, SWV and the two-variable model was determined by receiver operating characteristic (ROC) curve analysis. This analysis revealed stepwise increases in SWDS and SWV with increasing NAFLD severity. The accuracy of SWDS in diagnosing NASH was good (area under the ROC curve [AUC]: 0.88) and was superior to that of SWV (AUC: 0.76). The combination of SWV and SWDS exhibited higher performance (AUC: 0.90). SWV was higher than SWDS in participants with a fibrosis grade ≥2 (high-risk NASH). For identification of high-risk NASH, SWV exhibited the best diagnostic performance (AUC: 0.89), which was equivalent to that of the two-variable model (AUC: 0.88) and slightly higher than that of SWDS (AUC: 0.85). This study indicates that of the US-based markers, SWDS outperforms SWV in identifying NASH in rats and that combining the two markers may increase their clinical utility in guiding NAFLD and NASH treatment.

Clinical studies of magnetic resonance elastography from 1995 to 2021: Scientometric and visualization analysis based on CiteSpace

BACKGROUND

To assess the knowledge framework around magnetic resonance elastography (MRE) and to explore MRE research hotspots and emerging trends.

METHODS

The Science Citation Index Expanded of the Web of Science Core Collection was searched on 22 October 2021 for MRE-related studies published between 1995 and 2021. Excel 2016 and CiteSpace V (version 5.8.R3) were used to analyze the downloaded data.

RESULTS

In all, 1,236 articles published by 726 authors from 540 institutions in 40 countries were included in this study. The top 10 authors published 57.6% of all included articles. The 3 most productive countries were the USA (n=631), Germany (n=202), and France (n=134), and the 3 most productive institutions were the Mayo Clinic (n=240), Charité (n=131), and the University of Illinois (n=56). The USA and the Mayo Clinic had the highest betweenness centrality among countries and institutions, respectively, and played an important role in the field of MRE. In this study, the 24,347 distinct references were clustered into 48 categories via reasonable clustering using specific keywords, forming the knowledge framework. Among the 294 co-occurring keywords, "hepatic fibrosis", "stiffness", "skeletal muscle", "acoustic strain wave", "in vivo", and "non-invasive assessment" were research hotspots. "Diagnostic performance", "diagnostic accuracy", "hepatic steatosis", "chronic hepatitis B", "radiation force impulse", "children", and "echo" were frontier topics.

CONCLUSIONS

Scientometric and visualized analysis of MRE can provide information regarding the knowledge framework, research hotspots, frontier areas, and emerging trends in this field.

Nonalcoholic fatty liver disease and diabetes

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease in the world and represents a clinical-histopathologic entity where the steatosis component may vary in degree and may or may not have fibrotic progression. The key concept of NAFLD pathogenesis is excessive triglyceride hepatic accumulation because of an imbalance between free fatty acid influx and efflux. Strong epidemiological, biochemical, and therapeutic evidence supports the premise that the primary pathophysiological derangement in most patients with NAFLD is insulin resistance; thus the association between diabetes and NAFLD is widely recognized in the literature. Since NAFLD is the hepatic manifestation of a metabolic disease, it is also associated with a higher cardio-vascular risk. Conventional B-mode ultrasound is widely adopted as a first-line imaging modality for hepatic steatosis, although magnetic resonance imaging represents the gold standard noninvasive modality for quantifying the amount of fat in these patients. Treatment of NAFLD patients depends on the disease severity, ranging from a more benign condition of nonalcoholic fatty liver to nonalcoholic steatohepatitis. Abstinence from alcohol, a Mediterranean diet, and modification of risk factors are recommended for patients suffering from NAFLD to avoid major cardiovascular events, as per all diabetic patients. In addition, weight loss induced by bariatric surgery seems to also be effective in improving liver features, together with the benefits for diabetes control or resolution, dyslipidemia, and hypertension. Finally, liver transplantation represents the ultimate treatment for severe nonalcoholic fatty liver disease and is growing rapidly as a main indication in Western countries. This review offers a comprehensive multidisciplinary approach to NAFLD, highlighting its connection with diabetes.

Liver fibrosis assessment: MR and US elastography

Elastography has emerged as a preferred non-invasive imaging technique for the clinical assessment of liver fibrosis. Elastography methods provide liver stiffness measurement (LSM) as a surrogate quantitative biomarker for fibrosis burden in chronic liver disease (CLD). Elastography can be performed either with ultrasound or MRI. Currently available ultrasound-based methods include strain elastography, two-dimensional shear wave elastography (2D-SWE), point shear wave elastography (pSWE), and vibration-controlled transient elastography (VCTE). MR Elastography (MRE) is widely available as two-dimensional gradient echo MRE (2D-GRE-MRE) technique. US-based methods provide estimated Young's modulus (eYM) and MRE provides magnitude of the complex shear modulus. MRE and ultrasound methods have proven to be accurate methods for detection of advanced liver fibrosis and cirrhosis. Other clinical applications of elastography include liver decompensation prediction, and differentiation of non-alcoholic steatohepatitis (NASH) from simple steatosis (SS). In this review, we briefly describe the different elastography methods, discuss current clinical applications, and provide an overview of advances in the field of liver elastography.

Influence of liver stiffness heterogeneity on staging fibrosis in patients with nonalcoholic fatty liver disease

BACKGROUND AND AIMS

Despite that hepatic fibrosis often affects the liver globally, spatial distribution can be heterogeneous. This study aimed to investigate the effect of liver stiffness (LS) heterogeneity on concordance between MR elastography (MRE)-based fibrosis staging and biopsy staging in patients with NAFLD.

APPROACH AND RESULTS

We retrospectively evaluated data from 155 NAFLD patients who underwent liver biopsy and 3 Tesla MRE and undertook a retrospective validation study of 169 NAFLD patients at three hepatology centers. Heterogeneity of stiffness was assessed by measuring the range between minimum and maximum MRE-based LS measurement (LSM). Variability of LSM was defined as the stiffness range divided by the maximum stiffness value. The cohort was divided into two groups (homogenous or heterogeneous), according to whether variability was below or above the average for the training cohort. Based on histopathology and receiver operating characteristic (ROC) analysis, optimum LSM thresholds were determined for MRE-based fibrosis staging of stage 4 (4.43, kPa; AUROC, 0.89) and stage ≥3 (3.93, kPa; AUROC, 0.89). In total, 53 had LSM above the threshold for stage 4. Within this group, 30 had a biopsy stage of <4. In 86.7% of these discordant cases, variability of LSM was classified as heterogeneous. In MRE-based LSM stage ≥3, 88.9% of discordant cases were classified as heterogeneous. Results of the validation cohort were similar to those of the training cohort.

CONCLUSIONS

Discordance between biopsy- and MRE-based fibrosis staging is associated with heterogeneity in LSM, as depicted with MRE.

The Non-Invasive Ultrasound-Based Assessment of Liver Viscosity in a Healthy Cohort

Liver fibrosis is the most significant prognostic factor in chronic liver disease (CLD). Clinical practice guidelines recommend the use of non-invasive techniques, such as two-dimensional shear-wave elastography (2D-SWE), to assess liver stiffness as a marker of fibrosis. Several other factors influence liver stiffness in addition to liver fibrosis. It is presumed that changes due to necro-inflammation modify the propagation of shear waves (dispersion). Therefore, new imaging techniques that investigate the dispersion properties of shear waves have been developed, which can serve as an indirect method of measuring liver viscosity (Vi PLUS). Defining the reference values in healthy subjects among different age groups and genders and analyzing the factors that influence these values is essential. However, published data on liver viscosity are still limited. This is the first study that aimed to assess the normal range of liver viscosity values in subjects with healthy livers and analyze the factors that influence them. One hundred and thirty-one consecutive subjects with healthy livers were enrolled in this prospective study. The results showed that Vi PLUS is a highly feasible method. Liver stiffness, age and BMI influenced the liver viscosity values. The mean liver viscosity by Vi PLUS in subjects with healthy livers was 1.59 Pa·s.

Accelerating multi-echo chemical shift encoded water-fat MRI using model-guided deep learning

PURPOSE

To accelerate chemical shift encoded (CSE) water-fat imaging by applying a model-guided deep learning water-fat separation (MGDL-WF) framework to the undersampled k-space data.

METHODS

A model-guided deep learning water-fat separation framework is proposed for the acceleration using Cartesian/radial undersampling data. The proposed MGDL-WF combines the power of CSE water-fat imaging model and data-driven deep learning by jointly using a multi-peak fat model and a modified residual U-net network. The model is used to guide the image reconstruction, and the network is used to capture the artifacts induced by the undersampling. A data consistency layer is used in MGDL-WF to ensure the output images to be consistent with the k-space measurements. A Gauss-Newton iteration algorithm is adapted for the gradient updating of the networks.

RESULTS

Compared with the compressed sensing water-fat separation (CS-WF) algorithm/2-step procedure algorithm, the MGDL-WF increased peak signal-to-noise ratio (PSNR) by 5.31/5.23, 6.11/4.54, and 4.75 dB/1.88 dB with Cartesian sampling, and by 4.13/6.53, 2.90/4.68, and 1.68 dB/3.48 dB with radial sampling, at acceleration rates (R) of 4, 6, and 8, respectively. By using MGDL-WF, radial sampling increased the PSNR by 2.07 dB at R = 8, compared with Cartesian sampling.

CONCLUSIONS

The proposed MGDL-WF enables exploiting features of the water images and fat images from the undersampled multi-echo data, leading to improved performance in the accelerated CSE water-fat imaging. By using MGDL-WF, radial sampling can further improve the image quality with comparable scan time in comparison with Cartesian sampling.

Liver Stiffness Measurements by 2D Shear-Wave Elastography: Effect of Steatosis on Fibrosis Evaluation

Background: Hepatic steatosis has been shown to not effect liver stiffness measurements (LSM) by MR elastography (MRE). However, the effect of steatosis on LSM by 2D shear-wave elastography (SWE) remains controversial. Objective: To evaluate the effect of hepatic steatosis on the diagnostic performance of LSM from 2D SWE (hereafter, LSM2D-SWE) for evaluation of liver fibrosis, using LSM from MRE (hereafter, LSMMRE) as the reference standard. Methods: This retrospective study included 888 patients (442 women, 446 men; median age, 67 years) with chronic liver disease who underwent LSM by both 2D SWE and MRE within a 3-month window. Steatosis was also assessed on the ultrasound examinations by ultrasound-guided attenuation parameter (UGAP) and on the MRI examinations by MRI-based proton-density fat fraction (MRI-PDFF). Fibrosis stages and steatosis grades were classified using previously established thresholds. The effect of steatosis on LSM2D-SWE was evaluated using Kruskal-Wallis tests with post hoc tests and ROC analysis. Results: LSM2D-SWE was significantly higher in patients with severe steatosis than no steatosis by MRI-PDFF among patients with F0 fibrosis [5.5 (interquartile range [IQR], 4.7-6.0) vs 4.7 (IQR, 4.2-5.5), p=.009)] and F1 fibrosis [6.3 (IQR, 6.0-7.2) vs 5.9 (IQR, 5.0-6.6), p=.009]. LSM2D-SWE was significantly higher in patients with severe steatosis than no steatosis by UGAP among patients with F1 fibrosis [6.6 (IQR, 5.9-7.3) vs 5.9 (IQR, 5.1-6.5), p=.008)]. Otherwise, LSM2D-SWE did not vary significantly across steatosis grades at a given fibrosis stage (all p>.05). Sensitivity and specificity for ≥F1 fibrosis were 63.8% and 91.5% in patients without, versus 60.4% and 80.9% in patients with, severe steatosis by MRI-PDFF, and were 62.4% and 91.5% in patients without, versus 72.1% and 78.3% in patients with, severe steatosis by UGAP. Conclusion: Severe hepatic steatosis may result in overestimation of LSM2D-SWE in patients with no or mild steatosis, thus reducing specificity for liver fibrosis detection. Clinical impact: UGAP performed at the time of 2D SWE may help identify patients in whom LSM2D-SWE should be assessed with caution. In patients with no or mild steatosis by 2D SWE and severe steatosis by UGAP, MRE may help provide a more reliable measure of liver fibrosis.

Plasma Aldo-Keto Reductase Family 1 Member B10 as a Biomarker Performs Well in the Diagnosis of Nonalcoholic Steatohepatitis and Fibrosis

We found several blood biomarkers through computational secretome analyses, including aldo-keto reductase family 1 member B10 (AKR1B10), which reflected the progression of nonalcoholic fatty liver disease (NAFLD). After confirming that hepatic AKR1B10 reflected the progression of NAFLD in a subgroup with NAFLD, we evaluated the diagnostic accuracy of plasma AKR1B10 and other biomarkers for the diagnosis of nonalcoholic steatohepatitis (NASH) and fibrosis in replication cohort. We enrolled healthy control subjects and patients with biopsy-proven NAFLD (n = 102) and evaluated the performance of various diagnostic markers. Plasma AKR1B10 performed well in the diagnosis of NASH with an area under the receiver operating characteristic (AUROC) curve of 0.834 and a cutoff value of 1078.2 pg/mL, as well as advanced fibrosis (AUROC curve value of 0.914 and cutoff level 1078.2 pg/mL), with further improvement in combination with C3. When we monitored a subgroup of obese patients who underwent bariatric surgery (n = 35), plasma AKR1B10 decreased dramatically, and 40.0% of patients with NASH at baseline showed a decrease in plasma AKR1B10 levels to below the cutoff level after the surgery. In an independent validation study, we proved that plasma AKR1B10 was a specific biomarker of NAFLD progression across varying degrees of renal dysfunction. Despite perfect correlation between plasma and serum levels of AKR1B10 in paired sample analysis, its serum level was 1.4-fold higher than that in plasma. Plasma AKR1B10 alone and in combination with C3 could be a useful noninvasive biomarker for the diagnosis of NASH and hepatic fibrosis.

MR elastography in nonalcoholic fatty liver disease: inter-center and inter-analysis-method measurement reproducibility and accuracy at 3T

OBJECTIVES

To assess reproducibility and fibrosis classification accuracy of magnetic resonance elastography (MRE)-determined liver stiffness measured manually at two different centers, and by automated analysis software in adults with nonalcoholic fatty liver disease (NAFLD), using histopathology as a reference standard.

METHODS

This retrospective, cross-sectional study included 91 adults with NAFLD who underwent liver MRE and biopsy. MRE-determined liver stiffness was measured independently for this analysis by an image analyst at each of two centers using standardized manual analysis methodology, and separately by an automated analysis. Reproducibility was assessed pairwise by intraclass correlation coefficient (ICC) and Bland-Altman analysis. Diagnostic accuracy was assessed by receiver operating characteristic (ROC) analyses.

RESULTS

ICC of liver stiffness measurements was 0.95 (95% CI: 0.93, 0.97) between center 1 and center 2 analysts, 0.96 (95% CI: 0.94, 0.97) between the center 1 analyst and automated analysis, and 0.94 (95% CI: 0.91, 0.96) between the center 2 analyst and automated analysis. Mean bias and 95% limits of agreement were 0.06 ± 0.38 kPa between center 1 and center 2 analysts, 0.05 ± 0.32 kPa between the center 1 analyst and automated analysis, and 0.11 ± 0.41 kPa between the center 2 analyst and automated analysis. The area under the ROC curves for the center 1 analyst, center 2 analyst, and automated analysis were 0.834, 0.833, and 0.847 for distinguishing fibrosis stage 0 vs. ≥ 1, and 0.939, 0.947, and 0.940 for distinguishing fibrosis stage ≤ 2 vs. ≥ 3.

CONCLUSION

MRE-determined liver stiffness can be measured with high reproducibility and fibrosis classification accuracy at different centers and by an automated analysis.

KEY POINTS

• Reproducibility of MRE liver stiffness measurements in adults with nonalcoholic fatty liver disease is high between two experienced centers and between manual and automated analysis methods. • Analysts at two centers had similar high diagnostic accuracy for distinguishing dichotomized fibrosis stages. • Automated analysis provides similar diagnostic accuracy as manual analysis for advanced fibrosis.

Inhibition of 11β-Hydroxysteroid dehydrogenase-1 with AZD4017 in patients with nonalcoholic steatohepatitis or nonalcoholic fatty liver disease: A randomized, double-blind, placebo-controlled, phase II study

AIM

To evaluate whether short-term treatment with a selective 11β-Hydroxysteroid dehydrogenase-1 (11β-HSD1) inhibitor, AZD4017, would block hepatic cortisol production and thereby decrease hepatic fat in patients with nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH), with or without type 2 diabetes (T2D).

MATERIALS AND METHODS

This was a randomized, double-blind, placebo-controlled, phase 2 study conducted at two sites. Key inclusion criteria were the presence of NAFLD or NASH on magnetic resonance imaging (MRI) or recent biopsy positive for NASH. Enrolled patients were randomly assigned (1:1) to AZD4017 or placebo for 12 weeks. Primary outcomes were between-group differences in mean change from baseline to week 12 in liver fat fraction (LFF) and conversion of ¹³ C cortisone to ¹³ C cortisol in the liver.

RESULTS

A total of 93 patients were randomized; 85 patients completed treatment. The mean (standard deviation [SD]) change in LFF was -0.667 (5.246) and 0.139 (4.323) in the AZD4017 and placebo groups (P = 0.441). For patients with NASH and T2D, the mean (SD) change in LFF was significantly improved in the AZD4017 versus the placebo group (-1.087 [5.374] vs. 1.675 [3.318]; P = 0.033). Conversion of ¹³ C cortisone to ¹³ C cortisol was blocked in all patients in the AZD4017 group. There were no significant between-group differences (AZD4017 vs. placebo) in changes in fibrosis, weight, levels of liver enzymes or lipids, or insulin sensitivity.

CONCLUSION

Although the study did not meet one of the primary outcomes, AZD4017 blocked the conversion of ¹³ C cortisone to ¹³ C cortisol in the liver in all patients who received the drug. In patients with NASH and T2D, AZD4017 improved liver steatosis versus placebo.

Diagnostic Feasibility of Magnetic Resonance Elastography Radiomics Analysis for the Assessment of Hepatic Fibrosis in Patients With Nonalcoholic Fatty Liver Disease

OBJECTIVE

The aim of the study was to investigate the diagnostic feasibility of radiomics analysis using magnetic resonance elastography (MRE) to assess hepatic fibrosis in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

One hundred patients with suspected NAFLD were retrospectively enrolled. All patients underwent a liver parenchymal biopsy. Magnetic resonance elastography was performed using a 3.0-T scanner. After multislice segmentation of MRE images, 834 radiomic features were analyzed using a commercial program. Radiologic features, such as median and mean values of the regions of interest and variable clinical features, were analyzed. A random forest regressor was used to extract important radiomic, radiological, and clinical features. A random forest classifier model was trained to use these features to classify the fibrosis stage. The area under the receiver operating characteristic curve was evaluated using a classifier for fibrosis stage diagnosis.

RESULTS

The pathological hepatic fibrosis stage was classified as low-grade fibrosis (stages F0-F1, n = 82) or clinically significant fibrosis (stages F2-F4, n = 18). Eight important features were extracted from radiomics analysis, with the 2 most important being wavelet-high high low gray level dependence matrix dependence nonuniformity-normalized and wavelet-high high low gray level dependence matrix dependence entropy. The median value of the multiple small regions of interest was identified as the most important radiologic feature. Platelet count has been identified as an important clinical feature. The area under the receiver operating characteristic curve of the classifier using radiomics was comparable with that of radiologic measures (0.97 ± 0.07 and 0.96 ± 0.06, respectively).

CONCLUSIONS

Magnetic resonance elastography radiomics analysis provides diagnostic performance comparable with conventional MRE analysis for the assessment of clinically significant hepatic fibrosis in patients with NAFLD.

Visceral Adipose Tissue and Non-alcoholic Fatty Liver Disease in Patients with Type 2 Diabetes

AIM

To explore the association of visceral adipose tissue (VAT) area and non-alcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

This was a cross-sectional study comprising 100 patients with T2DM and 100 non-T2DM individuals, matched for age, sex, and body mass index (BMI). Transient elastography was used to assess hepatic steatosis and liver stiffness measurements (LSM). Controlled attenuation parameter (CAP) was used to quantify hepatic steatosis. To distinguish grades of hepatic steatosis, cutoff values were as follows: S1 ≥ 302, S2 ≥ 331, and S3 ≥ 337 dB/m. Moreover, VAT area was measured by dual-energy X-ray absorptiometry in accordance with validated protocols.

RESULTS

CAP score was significantly higher in participants with T2DM (294.61 ± 3.82 vs. 269.86 ± 3.86 dB/ m; P < 0.001). Furthermore, 42% of participants with T2DM had hepatic steatosis (S > S1: 302 dB/m), while this figure was 26% in non-T2DM group (P < 0.003). The mean liver stiffness measurement was also significantly higher in patients with T2DM (5.53 vs. 4.79 kPa; P < 0.001). VAT area was greater in patients with T2DM compared to non-T2DM individuals: 163.79 ± 47.98 cm² versus 147.49 ± 39.09 cm², P = 0.009. However, total and truncal fat mass were not different between the two groups. Age, BMI, waist circumference, ALT, CAP, and LSM were significantly associated with VAT area. BMI and VAT area were the important determinants of steatosis in both groups of participants with and without T2DM. Moreover, the VAT area was associated with the severity of hepatic steatosis and liver stiffness, independent of anthropometric measures of obesity.

CONCLUSION

VAT area is a major determinant of the severity of hepatic steatosis and liver stiffness in patient with T2DM.

Direct Comparison of US and MR Elastography for Staging Liver Fibrosis in Patients With Nonalcoholic Fatty Liver Disease

BACKGROUND & AIMS

As alternatives to the expensive liver biopsy for assessing liver fibrosis stage in patients with nonalcoholic fatty liver disease (NAFLD), we directly compared the diagnostic abilities of magnetic resonance elastography (MRE), vibration-controlled transient elastography (VCTE), and two-dimensional shear wave elastography (2D-SWE).

METHODS

Overall, 231 patients with biopsy-proven NAFLD were included. Intra- and inter-observer reproducibility was analyzed using intraclass correlation coefficient in a sub-group of 70 participants, in whom liver stiffness measurement (LSM) was performed by an elastography expert and an ultrasound expert who was an elastography trainee on the same day.

RESULTS

Valid LSMs were obtained for 227, 220, 204, and 201 patients using MRE, VCTE, 2D-SWE, and all three modalities combined, respectively. Although the area under the curve did not differ between the modalities for detecting stage ≥1, ≥2, and ≥3 liver fibrosis, it was higher for MRE than VCTE and 2D-SWE for stage 4. Sex was a significant predictor of discordance between VCTE and liver fibrosis stage. Skin-capsule distance and the ratio of the interquartile range of liver stiffness to the median were significantly associated with discordance between 2D-SWE and liver fibrosis stage. However, no factors were associated with discordance between MRE and liver fibrosis stage. Intra- and inter-observer reproducibility in detecting liver fibrosis was higher for MRE than VCTE and 2D-SWE.

CONCLUSIONS

MRE, VCTE, and 2D-SWE demonstrated excellent diagnostic accuracy in detecting liver fibrosis in patients with NAFLD. MRE demonstrated the highest diagnostic accuracy for stage 4 detection and intra- and inter-observer reproducibility. UMIN Clinical Trials Registry No. UMIN000031491.

Diagnosis of steatohepatitis and fibrosis in biopsy-proven nonalcoholic fatty liver diseases: including two-dimension real-time shear wave elastography and noninvasive fibrotic biomarker scores

BACKGROUND

The aim of this retrospective study was to evaluate the accuracy of two-dimension real-time shear wave elastography (2D-SWE) for the diagnosis of steatohepatitis and fibrosis in a cohort patients confirmed nonalcoholic fatty liver diseases (NAFLD) by liver biopsy, and compare with four noninvasive fibrotic biomarker scores (NFS, FIB-4, BARD and APRI).

METHODS

116 NAFLD patients and 23 normal control group were enrolled. The diagnostic performance of 2D-SWE and four noninvasive fibrotic biomarker scores was evaluated based on histopathological inflammation grades and fibrosis stages (F) according to Kleiner/Brunt et al.'s criteria classification. 5-fold cross validation and receiver operating characteristics curve (ROC) analyses were used to obtain an assessment of 2D-SWE and four noninvasive fibrotic biomarker scores; then cross validated area under the curves (AUCs) were compared using the test of Delong. Meanwhile, influence of steatosis on liver stiffness measurement (LSM) of 2D-SWE was also studied.

RESULTS

Liver stiffness measured by 2D-SWE proved to be an excellent diagnostic indicator for detecting steatohepatitis (AUROC =0.88), and fibrosis: ≥F2 stage (AUROC =0.86), ≥F3 stage (AUROC =0.89) and =F4 stage (AUROC =0.90) with the cutoff values were 7.3, 10.0, 11.6 and 12.6 kPa, respectively. Compared with fibrotic scores, 2D-SWE had the highest AUROC for predicting ≥F2, ≥F3, =F4 by Delong test (all P<0.05). No statistic differences of LSM were found among different steatosis levels (P=0.97).

CONCLUSIONS

The stiffness measured by 2D-SWE could be used to noninvasively identify steatohepatitis and stage fibrosis in NAFLD patients. Moreover, the diagnosis efficiency of the stiffness measured by 2D-SWE could not be influenced by steatosis.

Ultrasonographic index for the diagnosis of non-alcoholic steatohepatitis in patients with non-alcoholic fatty liver disease

BACKGROUND

Liver biopsy is a gold standard for the diagnosis of non-alcoholic steatohepatitis (NASH), but has several disadvantages including invasiveness, high cost, and sampling error. Ultrasonography (US) is a noninvasive imaging modality widely used in non-alcoholic fatty liver disease (NAFLD) patients. This study aimed: (I) to assess the feasibility of US in the prediction of NASH and (II) to develop various US indices combining US parameters and laboratory data for the detection of NASH in NAFLD patients and to compare the diagnostic performance of them.

METHODS

Sixty patients who underwent liver biopsy, gray-scale US [hepatorenal index (HRI) and shear-wave elastography (SWE)], and Fibroscan [controlled attenuation parameter (CAP) and transient elastography (TE)] for the evaluation of NASH were included. Patients were classified according to the NAFLD Activity Score (NAS) into the NASH (NAS ≥5) and non-NASH (NAS <5) groups. The diagnostic performance of HRI, CAP, SWE, TE, and laboratory data for grading steatosis, lobular inflammation, ballooning degeneration, and fibrosis was evaluated. After the identification of laboratory data that were independently associated with NASH through univariable and multivariable logistic regression analyses, various US indices were developed by combining US parameters with or without these laboratory data. The diagnostic performance of the US indices was assessed with obtaining area under the curve (AUC) and compared using DeLong test.

RESULTS

Twenty-five NASH and 35 non-NASH patients were included. The mean AUCs for grading steatosis were 0.871 using HRI and 0.583 using CAP. The mean AUCs for grading fibrosis and ballooning degeneration were 0.777 and 0.729 using SWE and 0.830 and 0.708 using TE, respectively. Aspartate aminotransferase (AST) was the only significant laboratory data associated with NASH (OR, 1.019; P=0.032). Using AST, the mean AUCs for grading lobular inflammation and ballooning degeneration were 0.712 and 0.775, respectively. Among various US indices, the index consisting of gray-scale US parameters (SWE and HRI) and AST showed the best diagnostic performance for the detection of NASH in NAFLD patients (AUC =0.806).

CONCLUSIONS

The index combining gray-scale US parameters and AST is useful for the detection of NASH and may be used to exclude the need for liver biopsy in NAFLD patients.

Quantitative ultrasound, elastography, and machine learning for assessment of steatosis, inflammation, and fibrosis in chronic liver disease

Objective

To develop a quantitative ultrasound (QUS)- and elastography-based model to improve classification of steatosis grade, inflammation grade, and fibrosis stage in patients with chronic liver disease in comparison with shear wave elastography alone, using histopathology as the reference standard.

Methods

This ancillary study to a prospective institutional review-board approved study included 82 patients with non-alcoholic fatty liver disease, chronic hepatitis B or C virus, or autoimmune hepatitis. Elastography measurements, homodyned K-distribution parametric maps, and total attenuation coefficient slope were recorded. Random forests classification and bootstrapping were used to identify combinations of parameters that provided the highest diagnostic accuracy. Receiver operating characteristic (ROC) curves were computed.

Results

For classification of steatosis grade S0 vs. S1-3, S0-1 vs. S2-3, S0-2 vs. S3, area under the receiver operating characteristic curve (AUC) were respectively 0.60, 0.63, and 0.62 with elasticity alone, and 0.90, 0.81, and 0.78 with the best tested model combining QUS and elastography features. For classification of inflammation grade A0 vs. A1-3, A0-1 vs. A2-3, A0-2 vs. A3, AUCs were respectively 0.56, 0.62, and 0.64 with elasticity alone, and 0.75, 0.68, and 0.69 with the best model. For classification of liver fibrosis stage F0 vs. F1-4, F0-1 vs. F2-4, F0-2 vs. F3-4, F0-3 vs. F4, AUCs were respectively 0.66, 0.77, 0.72, and 0.74 with elasticity alone, and 0.72, 0.77, 0.77, and 0.75 with the best model.

Conclusion

Random forest models incorporating QUS and shear wave elastography increased the classification accuracy of liver steatosis, inflammation, and fibrosis when compared to shear wave elastography alone.

Prospective assessment of liver stiffness by shear wave elastography in childhood obesity: a pilot study

PURPOSE

The increased incidence of childhood obesity and related non-alcoholic fatty liver disease (NAFLD) has determined the need to identify a non-invasive technique to diagnose and monitor NAFLD. Two-dimensional shear wave elastography (2D-SWE) has emerged as a reliable, non-invasive, tool to evaluate liver tissue elasticity in clinical practice. Aims of this study were to longitudinally evaluate 2D-SWE changes in relation to weight loss, metabolic profile, and body composition modifications and to investigate the correlation between 2D-SWE variation and clinical and biochemical indices of cardio-metabolic risk in obese children.

METHODS

Thirty-three children underwent anthropometric, bioimpedenziometric, fasting biochemical assessments, ultrasound, and SWE evaluations, at baseline (V0) and after a 12-months of follow-up (V12). Diet and physical activity programs have been prescribed to all patients according to European Society of Endocrinology and Pediatric Endocrine Society recommendations. Adherence to the prescribed diet and physical activity program was checked every 3 months during the 12-month of follow-up. Variation of all parameters was evaluated in intragroup and intergroup comparison analysis in children, who had not lost weight (Group A) and those who had lost weight (Group B) at V12. Study population was also analyzed dividing it into two groups with respect to 2D-SWE liver elasticity value ≤10.6 kPa or >10.6 kPa.

RESULTS

A significant reduction of mean 2D-SWE value was demonstrated both in the entire cohort (p = 0.002) and in Group B children (p = 0.004). Intragroup comparison analysis, between V0 and V12, documented a significant decrease of 2D-SWE and BMI SDS and a significant improvement of metabolic profile (decrease of HOMA-IR, HbA1c, oral glucose tolerance test 120-min glucose and insulin, triglycerides, triglycerides/HDL-ratio, transaminases, uric acid, and increase of Matsuda-index and HDL) in children of Group B but not in those of Group A. Intergroup comparison analysis showed significant differences for BMI, BMI SDS, transaminases and several parameters of glucose and lipid metabolism, between Group A and Group B children after 12-months of follow-up. No significant differences were documented with regard to clinical and biochemical variables by dividing the population in accordance with the 2D-SWE cut-off of 10.6 kPa.

CONCLUSIONS

These results suggested a relation between weight loss, metabolic profile improvement and 2D-SWE value reduction. SWE could play a significant role in the non-invasive assessment of NAFLD in children and adolescents with obesity.

Magnetic resonance elastography of the liver: everything you need to know to get started

Magnetic resonance elastography (MRE) of the liver has emerged as the non-invasive standard for the evaluation of liver fibrosis in chronic liver diseases (CLDs). The utility of MRE in the evaluation of different CLD in both adults and children has been demonstrated in several studies, and MRE has been recommended by several clinical societies. Consequently, the clinical indications for evaluation of CLD with MRE have increased, and MRE is currently used as an add-on test during routine liver MRI studies or as a standalone test. To meet the increasing clinical demand, MRE is being installed in many academic and private practice imaging centers. There is a need for a comprehensive practical guide to help these practices to deliver high-quality liver MRE studies as well as troubleshoot the common issues with MRE to ensure smooth running of the service. This comprehensive clinical practice review summarizes the indications and provides an overview on why to use MRE, technical requirements, system set-up, patient preparation, acquiring the data, and interpretation.

Subclinical steatohepatitis and advanced liver fibrosis in health examinees with nonalcoholic fatty liver disease (NAFLD) in 10 South Korean cities: A retrospective cross-sectional study

Background

Nonalcoholic steatohepatitis (NASH) has a risk of progressing to cirrhosis. The prevalence of NASH and its associated risk factors in community populations are relatively unknown. This study aimed to determine the prevalence of NASH and advanced liver fibrosis using magnetic resonance elastography (MRE), and determine those risk factors in health examinees with asymptomatic fatty liver.

Methods

This study consecutively selected subjects who underwent health checkups at 13 health-promotion centers in 10 Korean cities between 2018 and 2020. Hepatic steatosis and stiffness were assessed using ultrasonography and MRE, respectively. Stages of liver stiffness were estimated using MRE with cutoff values for NASH and advanced liver fibrosis of 2.91 and 3.60 kPa, respectively.

Results

The overall prevalence of NASH and advanced liver fibrosis in the subjects with fatty liver were 8.35% and 2.04%, respectively. Multivariate logistic regression analysis indicated that central obesity (OR = 5.12, 95% CI = 2.70–9.71), increased triglyceride (OR = 3.29, 95% CI = 1.72–6.29), abnormal liver function test (OR = 3.09, 95% CI = 1.66–5.76) (all P<0.001), and decreased high-density lipoprotein cholesterol (OR = 5.18, 95% CI = 1.78–15.05) (P = 0.003) were associated with NASH. The main risk factor for advanced liver fibrosis was diabetes (OR = 4.46, 95% CI = 1.14–17.48) (P = 0.032).

Conclusion

NASH or advanced liver fibrosis is found in one-tenth of health examinees with asymptomatic fatty liver. This suggests that early detection of NASH should be considered to allow early interventions such as lifestyle changes to prevent the adverse effects of NASH and its progression in health examinees with asymptomatic fatty liver.

A Step Closer to the "Fourth 90": A Practical Narrative Review of Diagnosis and Management of Nutritional Issues of People Living with HIV

The quality of life of people living with HIV (PLWH) has remarkably increased thanks to the introduction of combined antiretroviral therapy. Still, PLWH are exposed to an increased risk of cardiovascular diseases, diabetes, chronic kidney disease, and liver disease. Hence, the purpose of this review is to summarize the current knowledge about diagnosis and nutritional management with specific indication of macro and micronutrients intake for the main comorbidities of PLWH. In fact, a prompt diagnosis and management of lifestyle behaviors are fundamental steps to reach the “fourth 90”. To achieve an early diagnosis of these comorbidities, clinicians have at their disposal algorithms such as the Framingham Score to assess cardiovascular risk; transient elastography and liver biopsy to detect NAFLD and NASH; and markers such as the oral glucose tolerance test and GFR to identify glucose impairment and renal failure, respectively. Furthermore, maintenance of ideal body weight is the goal for reducing cardiovascular risk and to improve diabetes, steatosis and fibrosis; while Mediterranean and low-carbohydrate diets are the dietetic approaches proposed for cardioprotective effects and for glycemic control, respectively. Conversely, diet management of chronic kidney disease requires different nutritional assessment, especially regarding protein intake, according to disease stage and eventually concomitant diabetes.

Clinical and Molecular Biomarkers for Diagnosis and Staging of NAFLD

Non-alcoholic fatty liver disease (NAFLD) is the most common hepatic pathology in industrialized countries, affecting about 25% of the general population. NAFLD is a benign condition, however, it could evolve toward more serious diseases, including non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and finally, hepatocellular carcinoma (HCC). Liver biopsy is still the gold standard for NAFLD diagnosis. Due to the risks associated with liver biopsy and the impossibility to apply it on a large scale, it is now necessary to identify non-invasive biomarkers, which may reliably identify patients at higher risk of progression. Therefore, several lines of research have tried to address this issue by identifying novel biomarkers using omics approaches, including lipidomics, metabolomics and RNA molecules' profiling. Thus, in this review, we firstly report the conventional biomarkers used in clinical practice for NAFL and NASH diagnosis as well as fibrosis staging, and secondly, we pay attention to novel biomarkers discovered through omics approaches with a particular focus on RNA biomarkers (microRNAs, long-noncoding RNAs), showing promising diagnostic performance for NAFL/NASH diagnosis and fibrosis staging.

Magnetic resonance elastography biomarkers for detection of histologic alterations in nonalcoholic fatty liver disease in the absence of fibrosis

OBJECTIVES

To investigate associations between histology and hepatic mechanical properties measured using multiparametric magnetic resonance elastography (MRE) in adults with known or suspected nonalcoholic fatty liver disease (NAFLD) without histologic fibrosis.

METHODS

This was a retrospective analysis of 88 adults who underwent 3T MR exams including hepatic MRE and MR imaging to estimate proton density fat fraction (MRI-PDFF) within 180 days of liver biopsy. Associations between MRE mechanical properties (mean shear stiffness (|G*|) by 2D and 3D MRE, and storage modulus (G'), loss modulus (G″), wave attenuation (α), and damping ratio (ζ) by 3D MRE) and histologic, demographic and anthropometric data were assessed.

RESULTS

In univariate analyses, patients with lobular inflammation grade ≥ 2 had higher 2D |G*| and 3D G″ than those with grade ≤ 1 (p = 0.04). |G*| (both 2D and 3D), G', and G″ increased with age (rho = 0.25 to 0.31; p ≤ 0.03). In multivariable regression analyses, the association between inflammation grade ≥ 2 remained significant for 2D |G*| (p = 0.01) but not for 3D G″ (p = 0.06); age, sex, or BMI did not affect the MRE-inflammation relationship (p > 0.20).

CONCLUSIONS

2D |G*| and 3D G″ were weakly associated with moderate or severe lobular inflammation in patients with known or suspected NAFLD without fibrosis. With further validation and refinement, these properties might become useful biomarkers of inflammation. Age adjustment may help MRE interpretation, at least in patients with early-stage disease.

KEY POINTS

• Moderate to severe lobular inflammation was associated with hepatic elevated shear stiffness and elevated loss modulus (p =0.04) in patients with known or suspected NAFLD without liver fibrosis; this suggests that with further technical refinement these MRE-assessed mechanical properties may permit detection of inflammation before the onset of fibrosis in NAFLD. • Increasing age is associated with higher hepatic shear stiffness, and storage and loss moduli (rho = 0.25 to 0.31; p ≤ 0.03); this suggests that age adjustment may help interpret MRE results, at least in patients with early-stage NAFLD.

Insights into Nonalcoholic Fatty-Liver Disease Heterogeneity

The acronym nonalcoholic fatty-liver disease (NAFLD) groups a heterogeneous patient population. Although in many patients the primary driver is metabolic dysfunction, a complex and dynamic interaction of different factors (i.e., sex, presence of one or more genetic variants, coexistence of different comorbidities, diverse microbiota composition, and various degrees of alcohol consumption among others) takes place to determine disease subphenotypes with distinct natural history and prognosis and, eventually, different response to therapy. This review aims to address this topic through the analysis of existing data on the differential contribution of known factors to the pathogenesis and clinical expression of NAFLD, thus determining the different clinical subphenotypes observed in practice. To improve our understanding of NAFLD heterogeneity and the dominant drivers of disease in patient subgroups would predictably impact on the development of more precision-targeted therapies for NAFLD.

MRE combined with FIB-4 (MEFIB) index in detection of candidates for pharmacological treatment of NASH-related fibrosis

OBJECTIVE

Patients with non-alcoholic fatty liver disease (NAFLD) with ≥stage 2 fibrosis are at increased risk for liver-related mortality and are candidates for pharmacological therapies for treatment of NAFLD. The aim of this prospective cohort study is to examine the diagnostic accuracy of MR elastography (MRE) combined with fibrosis-4 (FIB-4) in diagnosing ≥stage 2 fibrosis (candidates for pharmacological therapies).

DESIGN

This is a cross-sectional analysis of a prospective cohort (University of California at San Diego (UCSD)-NAFLD) including 238 consecutive patients with contemporaneous MRE and biopsy-proven NAFLD. Non-alcoholic steatohepatitis-Clinical Research Network-Histologic Scoring System was used to assess histology. The radiologist and pathologist were blinded to clinical, pathological and imaging data, respectively. Receiver operating characteristics (ROCs) were determined to examine the diagnostic accuracy of MRE and FIB-4 for diagnosis of ≥stage 2 fibrosis in NAFLD. We then validated these findings in an independent validation cohort derived from Yokohama City University in Japan (Japan-NAFLD Cohort; N=222 patients).

RESULTS

In the UCSD-NAFLD (training) Cohort, MRE demonstrated a clinically significant diagnostic accuracy for the detection of ≥stage 2 fibrosis with an area under the ROC curve (AUROC) of 0.93 (95% CI 0.90 to 0.97) vs FIB-4 with an AUROC of 0.78 (95% CI 0.71 to 0.85), which was both clinically and statistically significant (p<0.0001). We then combined MRE with FIB-4 (MRE ≥3.3 kPa and FIB-4 ≥1.6) to develop a clinical prediction rule to rule in ≥stage 2 fibrosis patients which had positive predictive value (PPV) of 97.1% (p<0.02) in the UCSD-NAFLD cohort (AUROC of 0.90 (95% CI 0.85 to 0.95)) which remained significant at PPV of 91.0% (p<0.003) in the Japan-NAFLD Cohort (AUROC of 0.84 (95% CI 0.78 to 0.89)).

CONCLUSION

MRE combined with FIB-4 (MEFIB) index may be used for non-invasive identification of candidates for (≥stage 2 fibrosis) pharmacological therapy among patients with NAFLD with a high PPV.

Diagnostic accuracy of elastography and magnetic resonance imaging in patients with NAFLD: A systematic review and meta-analysis

BACKGROUND AND AIMS

Vibration-controlled transient elastography (VCTE), point shear wave elastography (pSWE), 2-dimensional shear wave elastography (2DSWE), magnetic resonance elastography (MRE), and magnetic resonance imaging (MRI) have been proposed as non-invasive tests for patients with non-alcoholic fatty liver disease (NAFLD). This study evaluated their diagnostic accuracy for liver fibrosis and non-alcoholic steatohepatitis (NASH).

METHODS

PubMED/MEDLINE, EMBASE and the Cochrane Library were searched for studies examining the diagnostic accuracy of these index tests, against histology as the reference standard, in adult patients with NAFLD. Two authors independently screened and assessed methodological quality of studies and extracted data. Summary estimates of sensitivity, specificity and area under the curve (sAUC) were calculated for fibrosis stages and NASH, using a random effects bivariate logit-normal model.

RESULTS

We included 82 studies (14,609 patients). Meta-analysis for diagnosing fibrosis stages was possible in 53 VCTE, 11 MRE, 12 pSWE and 4 2DSWE studies, and for diagnosing NASH in 4 MRE studies. sAUC for diagnosis of significant fibrosis were: 0.83 for VCTE, 0.91 for MRE, 0.86 for pSWE and 0.75 for 2DSWE. sAUC for diagnosis of advanced fibrosis were: 0.85 for VCTE, 0.92 for MRE, 0.89 for pSWE and 0.72 for 2DSWE. sAUC for diagnosis of cirrhosis were: 0.89 for VCTE, 0.90 for MRE, 0.90 for pSWE and 0.88 for 2DSWE. MRE had sAUC of 0.83 for diagnosis of NASH. Three (4%) studies reported intention-to-diagnose analyses and 15 (18%) studies reported diagnostic accuracy against pre-specified cut-offs.

CONCLUSIONS

When elastography index tests are acquired successfully, they have acceptable diagnostic accuracy for advanced fibrosis and cirrhosis. The potential clinical impact of these index tests cannot be assessed fully as intention-to-diagnose analyses and validation of pre-specified thresholds are lacking.

LAY SUMMARY

Non-invasive tests that measure liver stiffness or use magnetic resonance imaging (MRI) have been suggested as alternatives to liver biopsy for assessing the severity of liver scarring (fibrosis) and fatty inflammation (steatohepatitis) in patients with non-alcoholic fatty liver disease (NAFLD). In this study, we summarise the results of previously published studies on how accurately these non-invasive tests can diagnose liver fibrosis and inflammation, using liver biopsy as the reference. We found that some techniques that measure liver stiffness had a good performance for the diagnosis of severe liver scarring.

Necro-inflammatory activity grading in chronic viral hepatitis with three-dimensional multifrequency MR elastography

The purpose of this study was to assess the diagnostic value of multifrequency MR elastography for grading necro-inflammation in the liver. Fifty participants with chronic hepatitis B or C were recruited for this institutional review board-approved study. Their liver was examined with multifrequency MR elastography. The storage, shear and loss moduli, and the damping ratio were measured at 56 Hz. The multifrequency wave dispersion coefficient of the shear modulus was calculated. The measurements were compared to reference markers of necro-inflammation and fibrosis with Spearman correlations and multiple regression analysis. Diagnostic accuracy was assessed. At multiple regression analysis, necro-inflammation was the only determinant of the multifrequency dispersion coefficient, whereas fibrosis was the only determinant of the storage, loss and shear moduli. The multifrequency dispersion coefficient had the largest AUC for necro-inflammatory activity A ≥ 2 [0.84 (0.71–0.93) vs. storage modulus AUC: 0.65 (0.50–0.79), p = 0.03], whereas the storage modulus had the largest AUC for fibrosis F ≥ 2 [AUC (95% confidence intervals) 0.91 (0.79–0.98)] and cirrhosis F4 [0.97 (0.88–1.00)]. The measurement of the multifrequency dispersion coefficient at three-dimensional MR elastography has the potential to grade liver necro-inflammation in patients with chronic vial hepatitis.