Steatosis grading consistency between controlled attenuation parameter and MRI-PDFF in monitoring metabolic associated fatty liver disease

Application and research progress of magnetic resonance proton density fat fraction in metabolic dysfunction-associated steatotic liver disease: a comprehensive review

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD), formerly known as Non-Alcoholic Fatty Liver Disease (NAFLD), is a chronic liver disorder associated with disturbances in lipid metabolism. The disease is prevalent worldwide, particularly closely linked with metabolic syndromes such as obesity and diabetes. Magnetic Resonance Proton Density Fat Fraction (MRI-PDFF), serving as a non-invasive and highly quantitative imaging assessment tool, holds promising applications in the diagnosis and research of MASLD. This paper aims to comprehensively review and summarize the applications and research progress of MRI-PDFF technology in MASLD, analyze its strengths and challenges, and anticipate its future developments in clinical practice.

Association Between Ultraprocessed Food Consumption and Metabolic Disorders in Children and Adolescents with Obesity

BACKGROUND/OBJECTIVES

We investigated the effects of ultraprocessed food (UPF) consumption on metabolic disorders (e.g., adiposity, metabolic associated steatotic liver disease [MASLD], and insulin resistance) in children and adolescents with obesity to improve dietary guidelines and public health strategies.

METHODS

The dietary intake of 149 participants (aged 8-17 years) was assessed with food diaries. The NOVA classification system was used to classify food according to the degree of processing. Metabolic outcomes, including the fat mass index (FMI), hepatic fat percentage, and insulin resistance, were measured via dual-energy X-ray absorptiometry (DXA), magnetic resonance imaging proton density fat fraction (MRI-PDFF), and biochemical analysis, respectively.

RESULTS

Greater UPF consumption from baseline to the 6-month follow-up was significantly associated with increased insulin and decreased total cholesterol and LDL-cholesterol. UPF consumption was positively associated with the prevalence of MASLD (liver MRI-PDFF ≥ 5%; odds ratio T3 vs. T1 = 1.75; 95% confidence interval [CI] 1.03, 3.00), moderate-to-severe MASLD (liver MRI-PDFF ≥ 10%; OR T3 vs. T1 = 4.19; 95% CI 1.72, 10.22), and insulin resistance (OR T3 vs. T1 = 2.44; 95% CI 1.33, 4.48), after adjusting for covariates. A linear dose-response relationship was observed between UPF consumption and the odds of moderate-to-severe MASLD and insulin resistance.

CONCLUSIONS

Greater UPF consumption was strongly associated with MASLD and insulin resistance in children and adolescents with obesity, underscoring the importance of reducing UPF consumption through dietary guidelines and public health interventions to mitigate the risk of obesity-related metabolic conditions in young populations.

Impact of nomenclature as metabolic associated steatotic liver disease on steatotic liver disease prevalence and screening: a prospective population survey in Asians

BACKGROUND AND AIM

The introduction of the latest nomenclature, metabolic associated steatotic liver disease (MASLD), proposed by the multi-society without Asian society consensus statement, aims to redefine the diagnostic criteria for metabolic associated fatty liver disease (MAFLD). However, its effect on the epidemiology in Asia remains unclear.

METHOD

We conducted a population-based cross-sectional survey on fatty liver disease using multistage stratified random sampling of participants from Guangzhou, a representative area in China (ChiCTR2000033376). Demographic, socioeconomic, lifestyle, and laboratory data were collected. Hepatic steatosis and the severity of fibrosis were assessed using FibroScan.

RESULTS

A total of 7388 individuals were recruited, the proportion of which meeting the definitions for nonalcoholic fatty liver disease (NAFLD), MAFLD, and MASLD were 2359 (31.9%), 2666 (36.1%), and 2240 (30.3%), respectively. One hundred and twenty (1.6%) patients had cryptogenic SLD, and 537 (7.3%) patients were diagnosed with MetALD. MASLD did not significantly differ from NAFLD and MAFLD, except that MAFLD patients had a lower proportion of males, hypertension, and diabetes and were less likely to consume tea (P < 0.05). Both cryptogenic SLD and MASLD non-MAFLD patients exhibited milder hepatic steatosis and a lower frequency of liver injury than NAFLD, MAFLD, or MASLD patients (all P < 0.05). An increased HOMA-IR (adjusted OR: 1.33, 95% CI: 1.10-2.03) was associated with higher risk of moderate-to-severe steatosis for MASLD non-MAFLD patients, while consuming more cups of tea (P for trend = 0.015) showed inverse associations.

CONCLUSION

Irrespective of terminology used is that fatty liver disease is highly prevalent in the Han Chinese population. Differences in insulin resistance and lifestyle risk factors are associated with redefinition disparities.

Non-Invasive Diagnostic of NAFLD in Type 2 Diabetes Mellitus and Risk Stratification: Strengths and Limitations

The progressive potential of liver damage in type 2 diabetes mellitus (T2DM) towards advanced fibrosis, end-stage liver disease, and hepatocarcinoma has led to increased concern for quantifying liver injury and individual risk assessment. The combination of blood-based markers and imaging techniques is recommended for the initial evaluation in NAFLD and for regular monitoring to evaluate disease progression. Continued development of ultrasonographic and magnetic resonance imaging methods for accurate quantification of liver steatosis and fibrosis, as well as promising tools for the detection of high-risk NASH, have been noted. In this review, we aim to summarize available evidence regarding the usefulness of non-invasive methods for the assessment of NAFLD in T2DM. We focus on the power and limitations of various methods for diagnosis, risk stratification, and patient monitoring that support their implementation in clinical setting or in research field.

Impact of skeletal muscle mass evaluating methods on severity of metabolic associated fatty liver disease in non-elderly adults

The study aimed to explore the relationships of skeletal muscle mass with disease severity in metabolic-associated fatty liver disease (MAFLD) patients with different methods. Consecutive subjects undergoing bioelectrical impedance analysis were included. The steatosis grade and liver fibrosis were evaluated by MRI-derived proton density fat fraction and two-dimensional shear wave elastography. The appendicular skeletal muscle mass (ASM) was adjusted by height2 (ASM/H2), weight (ASM/W) and BMI (ASM/BMI). Overall, 2223 subjects (50·5 %, MAFLD; 46·9 %, male) were included, with the mean age 37·4 ± 10·6 years. In multivariate logistic regression analysis, the subjects with the lowest quartile (Q1) of ASM/W or ASM/BMI had higher risk ratios for MAFLD (OR (95 % CI) in male: 2·57 (1·35, 4·89), 2·11(1·22, 3·64); in female: 4·85 (2·33, 10·01), 4·81 (2·52, 9·16), all P < 0·05, all for Q1 v. Q4). The MAFLD patients with lower quartiles of ASM/W had the higher risk OR for insulin resistance (IR), both in male and female (2·14 (1·16, 3·97), 4·26 (1·29, 14·02) for Q4 v. Q1, both P < 0·05). While the significant OR were not observed when ASM/H2 and ASM/BMI were used. There were significant dose-dependent associations between decreased ASM/W as well as ASM/BMI and moderate-severe steatosis (2·85(1·54, 5·29), 1·90(1·09, 3·31), both P < 0·05) in male MAFLD patients. In conclusion, ASM/W is superior to ASM/H2 and ASM/BMI in predicting the degree of MAFLD. A lower ASM/W is associated with IR and moderate-severe steatosis in non-elderly male MAFLD.

Comparisons of Insulin Resistance- and Steatosis-Based Scores in Monitoring Metabolic Associated Fatty Liver Disease Treatment Response

BACKGROUND

Quantitative measurements of liver fat contents (LFCs) by magnetic resonance imaging derived-proton density fat fraction (MRI-PDFF) are accurate but limited by availability, convenience, and expense in the surveillance of metabolic associated fatty liver (MAFLD). Insulin resistance (IR) and steatosis-associated serum indices are useful in screening for MAFLD, but their value in monitoring MAFLD with or without chronic hepatitis B virus (CHB) infection remains unclear and we aimed to evaluate these scores in predicting changes in LFC.

METHODS

We conducted a prospective study between January 2015 and December 2021 with 620 consecutive participants with MAFLD (212 participants with CHB) who received a 24-week lifestyle intervention. The homeostasis model assessment of IR (HOMA-IR), HOMA2 index, glucose-insulin ratio, quantitative insulin sensitivity check index, fasting insulin resistance index, fatty liver index (FLI), hepatic steatosis index (HSI), liver fat score (LFS), visceral adiposity index, and triglycerides * glucose were calculated.

RESULTS

When using endpoints such as LFS improvements of ≥5% or 10% or escalations of ≥5%, LFS had the highest area under the curve (AUC) values at all endpoints for MAFLD alone (0.756, 95% CI: 0.707-0.805; 0.761, 95% CI: 0.705-0.818; 0.807, 95% CI: 0.713-0.901, all p < 0.05, respectively). With CHB, the FLI (AUC = 0.750) and HIS (AUC = 0.770) exhibited the highest AUCs between the former two outcomes, respectively, but no score could predict LFC escalation of ≥5%.

CONCLUSION

Among IR and steatosis scores, changes in LFC through lifestyle interventions can be captured with LFS possessing moderate precision but not in those with CHB.

Which obesity index is the most useful marker for predicting hepatic steatosis in children and adolescents with obesity? A cross-sectional study using quantitative magnetic resonance imaging

INTRODUCTION

We aimed to evaluate the relationships between hepatic steatosis and various indices of obesity, and to identify the most useful index for the prediction of hepatic steatosis in children and adolescents with obesity.

METHODS

A total of 226 children and adolescents with a mean body mass index (BMI) z-score of 2.65 and a mean age of 11.4 years were subjected to anthropometric and body composition measurements, laboratory testing, abdominal fat mass assessment, and hepatic fat accumulation by magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF). The participants were divided into quartiles according to the severity of their hepatic steatosis, and the presence of hepatic steatosis was defined using an MRI-PDFF ≥ 5%.

RESULTS

The multivariate ordinal regression analysis showed that the severity of hepatic steatosis was positively associated with BMI, waist circumference, waist-to-hip ratio, waist-to-height ratio, fat mass, fat-free mass, visceral adiposity, and abdominal subcutaneous adiposity. Higher activities of liver enzymes and higher concentrations of triglyceride, C-reactive protein, fasting insulin, and leptin were associated with more severe hepatic steatosis, whereas high-density lipoprotein-cholesterol and adiponectin were negatively associated with hepatic steatosis. The indices of obesity with areas under the receiver operating characteristic curves (AUCs) > 0.8 for the prediction of hepatic steatosis were liver enzymes, visceral adipose tissue area, waist-to-hip ratio, and waist-to-height ratio.

CONCLUSION

The severity of hepatic steatosis significantly correlated with various indices of obesity and cardiometabolic markers in children and adolescents with obesity. The indices of abdominal obesity would be the most useful for the prediction of hepatic steatosis.

The evaluation of liver abnormalities in inflammatory bowel disease patients

PURPOSE OF REVIEW

Develop a clinical presentation-based approach for common liver abnormalities encountered by providers caring for patients with inflammatory bowel disease (IBD). Develop a treatment pathway for those with nonalcoholic fatty liver disease (NAFLD) arising in IBD. Discuss recent studies of prevalence, incidence, risk factors, and prognosis NAFLD in the IBD population.

RECENT FINDINGS

The work-up for liver abnormalities should be approached systematically in IBD patients, similar to the general population, while still appreciating the differing prevalence of underlying liver diagnoses. Although immune mediated liver diseases occur commonly in patients with IBD, NAFLD is still the most common liver disease in patients with IBD paralleling its expanding prevalence in the general population. IBD is also an independent risk factor for NAFLD, developing in many patients with lower degrees of adiposity. Furthermore, the more severe histologic subtype, nonalcoholic steatohepatitis, is both more common and difficult to treat considering the lower effectiveness of weight loss interventions.

SUMMARY

Having a standard approach to the most common liver disease presentations and care pathway for NAFLD will improve the quality of care provided and ease the medical decision making complexity for IBD patients. The early identification of these patients should prevent the development of irreversible complications like cirrhosis or hepatocellular carcinoma.

Non-invasive evaluation of liver steatosis with imaging modalities: New techniques and applications

In the world, nonalcoholic fatty liver disease (NAFLD) accounts for majority of diffuse hepatic diseases. Notably, substantial liver fat accumulation can trigger and accelerate hepatic fibrosis, thus contributing to disease progression. Moreover, the presence of NAFLD not only puts adverse influences for liver but is also associated with an increased risk of type 2 diabetes and cardiovascular diseases. Therefore, early detection and quantified measurement of hepatic fat content are of great importance. Liver biopsy is currently the most accurate method for the evaluation of hepatic steatosis. However, liver biopsy has several limitations, namely, its invasiveness, sampling error, high cost and moderate intraobserver and interobserver reproducibility. Recently, various quantitative imaging techniques have been developed for the diagnosis and quantified measurement of hepatic fat content, including ultrasound- or magnetic resonance-based methods. These quantitative imaging techniques can provide objective continuous metrics associated with liver fat content and be recorded for comparison when patients receive check-ups to evaluate changes in liver fat content, which is useful for longitudinal follow-up. In this review, we introduce several imaging techniques and describe their diagnostic performance for the diagnosis and quantified measurement of hepatic fat content.

Treatment of obesity and metabolic-associated fatty liver disease with a diet or orlistat: A randomized controlled trial

BACKGROUND

Losing weight by lifestyle interventions is the first-line treatment for metabolic-associated fatty liver disease (MAFLD) but is limited by low compliance.

OBJECTIVES

This study aimed to compare the effects of orlistat or an experimental high-protein/lower-carbohydrate diet with a control diet in Asian patients with obesity and MAFLD.

METHODS

A total of 118 Asian patients with obesity and MAFLD confirmed with MRI-based proton density fat fraction with Dixon sequence were enrolled and allocated to the control group, the orlistat group, or the experimental diet group for 24 wk. The primary endpoint was the relative change in liver fat content (LFC) assessed by MRI-based proton density fat fraction.

RESULTS

A total of 118 subjects with obesity and MAFLD were randomly assigned to the control group (n = 39), the orlistat group (n = 40), or the experimental diet group (n = 39). All 3 groups demonstrated improvement in liver steatosis at wk 24. The absolute decrease in LFC in the orlistat group was 9.1% and 5.4% in the experimental diet group, both significantly higher than that in the control group (P < 0.05). The relative reduction in LFC was 30.2% in the experimental diet group, which was significantly higher than the 12.2% observed in the control group (P = 0.01).

CONCLUSIONS

Orlistat and the experimental diet group reduced liver steatosis compared to the control group. This trial was registered at Chinese Clinical Trial Registry (ChiCTR-1900027172). http://www.chictr.org.cn.

Prevalence and Risk Factors of Metabolic-Associated Fatty Liver Disease Among Hospital Staff

Background

The prevalence of metabolism-related fatty liver disease (MAFLD) has been rarely reported in hospital staffs. The aim of this study was to assess the prevalence and risk factors for MAFLD in hospital staffs aged ≥18 years.

Methods

Based on type B ultrasonic, hospital staffs who underwent medical examinations at the second Affiliated Hospital of Hainan Medical University from January 2022 to March 2022 were classified into health control group (661 subjects) and MAFLD group (223 subjects), demographic, biochemical and blood examination information were compared between 2 groups. Independent risk factors for MAFLD were determined by logistic regression. Predictive values of risk factors of MAFLD were evaluated by receiver operating characteristic (ROC) curves.

Results

The prevalence of MAFLD was 33.7%. Older age (OR=1.08, p<0.001), H. pylori infection (OR=0.234, p=0.02), triglyceride-glucose (TyG) (OR=7.001, p<0.001), low-density lipoprotein cholesterol (LDL-C) (OR=2.076, p=0.028), red blood cell (RBC) (OR=2.386, p=0.001), eating out (OR=0.048, p=0.001), regular exercise (OR=23.017, p<0.001), and overweight (OR=3.891, p=0.003) were independently associated factors for MAFLD. The AUC of model predicting MAFLD is 0.910 [95% CI (0.886, 0.934)], with 0.794 sensitivity, 0.908 specificity. The diagnostic value of model was higher in the female MAFLD group after stratified analysis according to gender. The model showed that TyG was the factor contributing more to MAFLD. The diagnostic value of TyG was higher in the female MAFLD group than male MAFLD group.

Conclusion

The prevalence of MAFLD among hospital staffs was 33.7%. TyG can be used to predict MAFLD especially for female hospital staffs for early intervention.

The Impact of an SGLT2 Inhibitor versus Ursodeoxycholic Acid on Liver Steatosis in Diabetic Patients

Non-alcoholic fatty liver disease (NAFLD) is related to metabolic syndrome via insulin resistance, where preventing disease progression is crucial in the management process. The study included 240 NAFLD patients with type 2 diabetes who were randomly allocated into empagliflozin 25 mg (EMPA group), ursodeoxycholic acid 250 mg (UDCA group), or the control group (placebo). The study outcomes included: changes in liver fat content (LFC; %) (utilizing the Dixon-based MRI-PDFF approach), liver enzymes, lipid and glycemic profiles, FIB-4 index, and non-alcoholic fatty liver score (NFS). All endpoints were assessed at baseline and after 6 months. EMPA outperformed UDCA and placebo in decreasing LFC (−8.73% vs. −5.71% vs. −1.99%; p < 0.0001). In post-treatment ultrasound images and MRI-PDFF calculations, more patients had normal fatty liver grade (no steatosis or LFC < 6.5%) with EMPA compared to UDCA. EMPA and UDCA showed significant regression in the FIB-4 index (−0.34 vs. −0.55; p = 0.011) and NFS scores (−1.00 vs. −1.11; p = 0.392), respectively. UDCA achieved higher reductions in insulin resistance than EMPA (p = 0.03); however, only EMPA significantly increased beta-cell function (54.20; p = 0.03). When exploring the differences between the two drugs, EMPA was better in decreasing LFC (%), while UDCA achieved higher reductions in liver fibrosis scores. Both showed a similar safety profile in managing liver steatosis.

Quantification of Hepatic Steatosis by Ultrasound: Prospective Comparison With MRI Proton Density Fat Fraction as Reference Standard

BACKGROUND. Multiple ultrasound platforms now provide quantitative measures of hepatic steatosis. One such measure is the ultrasound-derived fat fraction (UDFF), which combines attenuation and backscatter quantification. OBJECTIVE. The purpose of this study was to characterize agreement between UDFF and MRI proton-density fat fraction (PDFF) measurements. METHODS. This prospective cross-sectional study enrolled 56 overweight and obese adolescents and adults (age ≥ 16 years) who underwent investigational ultrasound (deep abdominal transducer) and MRI examinations of the liver during a single visit from August 2020 to October 2020. Ultrasound examinations included three UDFF acquisitions of five measurements each (15 measurements total), and an overall median of medians was computed (UDFFoverall). MRI examinations included three PDFF acquisitions with calculation of an overall median PDFF. Spearman rank-order correlation was computed between UDFF and MRI PDFF measurements. Intraclass correlation coefficients and Bland-Altman difference plots were used to assess agreement. ROC curves were used to assess diagnostic performance of UDFF for detecting MRI PDFF of 5.5% or more. RESULTS. Median participant age was 32.5 years (IQR, 24.0-39.0 years); 40 participants were female, and 16 were male. A total of 34 (60.7%) participants had an MRI PDFF of 5.5% or more. UDFFoverall was 10.5% (IQR, 5.0-20.0%); median MRI PDFF was 6.1% (IQR, 3.4-13.7%). UDFFoverall was positively associated with MRI PDFF (ρ, 0.82; p < .001; intraclass correlation coefficient, 0.84 [95% CI, 0.59-0.93]). Mean bias between UDFF and PDFF was 4.0% (95% limits of agreement, -7.9% to 15.9%), with similar bias if summarizing UDFF by the first five measurements (4.4%), first three measurements (4.4%), or first measurement (4.6%). UDFFoverall AUC was 0.90 (95% CI, 0.79-0.96) for MRI PDFF of 5.5% or more; AUC was not significantly different when it was based on the number of UDFF measurements (p = .11-.97 for all pairwise AUC comparisons). UDFFoverall cutoff of more than 5% had sensitivity of 94.1% and specificity of 63.6% for diagnosing MRI PDFF of 5.5% or more. CONCLUSION. Measurements of hepatic steatosis using UDFF show strong agreement with measurements by MRI PDFF. A UDFFoverall cutoff of more than 5% provides high AUC and sensitivity, albeit low specificity, for detection of MRI PDFF of 5.5% or more. CLINICAL IMPACT. UDFF may have a clinical role in detection of hepatic steatosis. A reduced number of individual measurements is likely sufficient for determining an overall UDFF value. TRIAL REGISTRATION. ClinicalTrials.gov: NCT04523584.

Novel metabolic classification for extrahepatic complication of metabolic associated fatty liver disease: A data-driven cluster analysis with international validation

BACKGROUND

Traditional classification systems of metabolic-associated fatty liver disease (MAFLD) do not account for the high rate of extrahepatic complications. To create a new classification of MAFLD using metabolic parameters to identify risks of complications more accurately.

METHODS

The retrospective study included MAFLD patients from the First Affiliated Hospital of Sun Yat-sen University for model development, and the model was validated respectively using Chinese cohort and UK Biobank database. Cluster analysis with k-means cluster was built using age, body mass index (BMI), glycosylated hemoglobin (HbA1c), total cholesterol/high density lipoprotein cholesterol (HDL-C) ratio, triglyceride, and lipoprotein(a) [Lp(a)] levels. Cox regression models were used to compare the risk of type 2 diabetes (T2DM), chronic heart disease (CHD), stroke and mortality between the clusters.

RESULTS

1038 MAFLD patients from cross-sectional population were recruited for the model derivation, with 10,451 cases (33.4 % of MAFLD) from Chinese cohort and 304,141 cases (34.9 % of MAFLD, 1010 cases with magnetic resonance imaging proton density fat fraction measurement [MRI-PDFF]) from the international cohort validated. Five replicable clusters of MAFLD patients were identified: Cluster 1(mild obesity and dyslipidemia-related), Cluster 2 (age related), Cluster 3 (severe insulin resistance-related), Cluster 4[high Lp(a)-related], and Cluster 5 (severe mixed hyperlipidemia-related). Patients in different clusters exhibited differences in the development of T2DM, CHD, stroke and all-causes mortality. Patients in Cluster 3 had significantly worst survival outcomes and higher risks of T2DM and CVD than those in other clusters.

CONCLUSION

The novel classification offers improved discrimination of new-onset MAFLD patients with different metabolic complications.

Magnetic resonance imaging improves stratification of fibrosis and steatosis in patients with chronic liver disease

PURPOSE

We aimed to compare the diagnostic accuracy of magnetic resonance imaging (MRI) and transient elastography (TE) in assessing liver fibrosis and steatosis in patients with chronic liver disease (CLD).

METHODS

Patients who underwent liver biopsy or liver surgery at two academic hospitals between 2017 and 2021 were retrospectively recruited. The stages of liver fibrosis and steatosis were evaluated using histologic examination. Liver stiffness (LS) was assessed using MR elastography (LS_MRE) and TE (LS_TE). Liver steatosis was assessed using proton density fat fraction (PDFF) and controlled attenuation parameter (CAP).

RESULTS

The mean age of the study population (n = 280) was 53.6 years and male sex predominated (n = 199, 71.1%). Nonalcoholic fatty liver disease was the most prevalent (n = 127, 45.5%), followed by hepatitis B virus (n = 112, 40.0%). Hepatocellular carcinoma was identified in 130 patients (46.4%). The proportions of F0, F1, F2, F3, and F4 fibrosis were 13.2%, 31.1%, 9.6%, 16.4%, and 29.7%, respectively. LS_MRE had a significantly greater AUROC value than LS_TE for detecting F2-F4 (0.846 vs. 0.781, P = 0.046), whereas LS_MRE and LS_TE similarly predicted F1-4, F3-4, and F4 (all P > 0.05). The proportions of S0, S1, S2, and S3 steatosis were 34.7%, 49.6%, 12.5%, and 3.2%, respectively. PDFF had significantly greater AUROC values than CAP in predicting S1-3 (0.922 vs. 0.806, P < 0.001) and S2-3 (0.924 vs. 0.795, P = 0.005); however, PDFF and CAP similarly predicted S3 (P = 0.086).

CONCLUSION

MRI exhibited significantly higher diagnostic accuracy than TE for detecting significant fibrosis and mild or moderate steatosis in patients with CLD.

Ultrasound Methods for the Assessment of Liver Steatosis: A Critical Appraisal

The prevalence of the non-alcoholic fatty liver disease has reached major proportions, being estimated to affect one-quarter of the global population. The reference techniques, which include liver biopsy and the magnetic resonance imaging proton density fat fraction, have objective practical and financial limitations to their routine use in the detection and quantification of liver steatosis. Therefore, there has been a rising necessity for the development of new inexpensive, widely applicable and reliable non-invasive diagnostic tools. The controlled attenuation parameter has been considered the point-of-care technique for the assessment of liver steatosis for a long period of time. Recently, many ultrasound (US) system manufacturers have developed proprietary software solutions for the quantification of liver steatosis. Some of these methods have already been extensively tested with very good performance results reported, while others are still under evaluation. This manuscript reviews the currently available US-based methods for diagnosing and grading liver steatosis, including their classification and performance results, with an appraisal of the importance of this armamentarium in daily clinical practice.

Accuracy of controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) for assessing steatosis and fibrosis in non-alcoholic fatty liver disease: A systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common chronic liver disease, and among the non-invasive tests, controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) have shown better diagnostic performance in NAFLD. This meta-analysis aimed to evaluate the performance of CAP and LSM for assessing steatosis and fibrosis in NAFLD.

METHODS

We searched the PubMed, Web of Science, Cochrane Library, and Embase databases for relevant articles published up to February 13^th, 2022, and selected studies that met the inclusion and exclusion criteria, and evaluated the quality of evidence. Then we pooled sensitivity (SE), specificity (SP), and area under receiver operating characteristic (AUROC) curves. A random effect model was applied regardless of heterogeneity. Meta-regression analysis and subgroup analysis were performed to explore heterogeneity, and Fagan plot analysis was used to evaluate clinical utility. This meta-analysis was completed in Nanjing, Jiangsu and registered on PROSPERO (CRD42022309965).

FINDINGS

A total of 10537 patients from 61 studies were included in our meta-analysis. The AUROC of CAP were 0·924, 0·794 and 0·778 for steatosis grades ≥ S1, ≥ S2 and = S3, respectively, and the AUROC of LSM for detecting fibrosis stages ≥ F1, ≥ F2, ≥ F3, and = F4 were 0·851, 0·830, 0·897 and 0·925, respectively. Subgroup analysis revealed that BMI ≥ 30 kg/m² had lower accuracy for diagnosing S ≥ S1, ≥ S2 than BMI<30 kg/m². For the mean cut-off values, significant differences were found in CAP values among different body mass index (BMI) populations and LSM values among different regions. For diagnosing S ≥ S1, ≥ S2 and = S3, the mean CAP cut-off values for BMI ≥ 30 kg/m² were 30·7, 28·2, and 27·9 dB/m higher than for BMI < 30 kg/m² (P = 0·001, 0·001 and 0·018, respectively). For diagnosing F ≥ F2 and = F4, the mean cut-off values of Europe and America were 0·96 and 2·03 kPa higher than Asia (P = 0·027, P = 0·034), respectively. In addition, the results did not change significantly after sensitivity analysis and the trim and fill method to correct for publication bias, proving that the conclusions are robust.

INTERPRETATION

The good performance of CAP and LSM for the diagnosis of mild steatosis (S ≥ S1), advanced liver fibrosis (F ≥ F3), and cirrhosis (F = F4) can be used to screen for NAFLD in high-risk populations. Of note, the accuracy of CAP for the detection of steatosis in patients with obesity is reduced and requires specific diagnostic values. For LSM, the same diagnostic values can be used when the appropriate probes are selected based on BMI and the automated probe selection tool. The performance of CAP and LSM in assessing steatosis in patients with obesity, moderate to severe steatosis, and low-grade fibrosis should be further validated and improved in the future.

FUNDING

The study was funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).

Tissue attenuation imaging and tissue scatter imaging for quantitative ultrasound evaluation of hepatic steatosis

We aimed to assess the feasibility of ultrasound-based tissue attenuation imaging (TAI) and tissue scatter distribution imaging (TSI) for quantification of liver steatosis in patients with nonalcoholic fatty liver disease (NAFLD). We prospectively enrolled 101 participants with suspected NAFLD. The TAI and TSI measurements of the liver were performed with a Samsung RS85 Prestige ultrasound system. Based on the magnetic resonance imaging proton density fat fraction (MRI-PDFF), patients were divided into ≤5%, 5-10%, and ≥10% of MRI-PDFF groups. We determined the correlation between TAI, TSI, and MRI-PDFF and used multiple linear regression analysis to identify any association with clinical variables. The diagnostic performance of TAI, TSI was determined based on the area under the receiver operating characteristic curve (AUC). The intraclass correlation coefficient (ICC) was calculated to assess interobserver reliability. Both TAI (rs = 0.78, P < .001) and TSI (rs = 0.68, P < .001) showed significant correlation with MRI-PDFF. TAI overperformed TSI in the detection of both ≥5% MRI-PDFF (AUC = 0.89 vs 0.87) and ≥10% (AUC = 0.93 vs 0.86). MRI-PDFF proved to be an independent predictor of TAI (β = 1.03; P < .001), while both MRI-PDFF (β = 50.9; P < .001) and liver stiffness (β = -0.86; P < .001) were independent predictors of TSI. Interobserver analysis showed excellent reproducibility of TAI (ICC = 0.95) and moderate reproducibility of TSI (ICC = 0.73). TAI and TSI could be used successfully to diagnose and estimate the severity of hepatic steatosis in routine clinical practice.

Global Prevalence and Clinical Characteristics of Metabolic-associated Fatty Liver Disease: A Meta-Analysis and Systematic Review of 10 739 607 Individuals

BACKGROUND AND AIMS

Metabolic-associated fatty liver disease (MAFLD) was proposed as a better definition of nonalcoholic fatty liver disease (NAFLD) to encompass the metabolic dysregulation associated with NAFLD. This redefinition challenges our understanding of the disease. Hence, this study sought to conduct an updated analysis of the prevalence, clinical characteristics, and associated factors of MAFLD, with a further sensitivity analysis done based on lean and nonobese MAFLD individuals.

METHODS

Medline and Embase databases were searched to include articles on MAFLD. Meta-analysis of proportions was conducted using the generalized linear mix model. Associating factors were evaluated in conventional pairwise meta-analysis with sensitivity analysis on lean and nonobese MAFLD.

RESULTS

From pooled analysis involving 3 320 108 individuals, the overall prevalence of MAFLD was 38.77% (95% CI 32.94% to 44.95%); 5.37% (95% CI 4.36% to 6.59%) and 29.78% (95% CI 26.06% to 33.79%) of lean and nonobese individuals, respectively, had MAFLD. Metabolic complications such as hypertension [odds ratio (OR) 2.63, 95% CI 1.85 to 3.74, P < 0.0001 and OR 2.03; 95% CI 1.74 to 2.38, P < 0.0001, respectively] and diabetes (OR 3.80, 95% CI 2.65 to 5.43, P < 0.0001 and OR 3.46, 95% CI 2.81 to 4.27, P < 0.0001, respectively) were found as significant associating factors associated with lean and nonobese MAFLD.

CONCLUSIONS

This meta-analysis supports previous studies in reporting MAFLD to affect more than a third of the global population. While exploration of the pathogenic basis of fatty liver disease without metabolic dysregulation is required, the emphasis on management of concomitant metabolic disease in MAFLD can improve multidisciplinary efforts in managing the complex disease.