MR quantification of total liver fat in patients with impaired glucose tolerance and healthy subjects

Specific metabolic impairments indicate loss of sustained liver improvements in metabolic dysfunction-associated steatotic liver disease treatment

Background

High liver fat content (LFC) induces increased risks of both hepatic and extrahepatic progression in metabolic dysfunction-associated steatotic liver disease (MASLD), while maintaining a significant decline in magnetic resonance imaging-based proton density fat fraction (MRI-PDFF) (≥30% decline relative to baseline) without worsening fibrosis results in improved histological severity and prognosis. However, the factors associated with the loss of sustained responses to treatment remain unclear, and we aim to identify them.

Methods

Consecutive treatment-naïve MASLD patients between January 2015 and February 2022, with follow-up until April 2023, were included in this prospective cohort study. LFC quantified by MRI-PDFF and liver stiffness measurements (LSM) determined by two-dimensional shear wave elastography (2D-SWE) were evaluated at weeks 0, 24 and 48. MRI-PDFF response was defined as a ≥30% relative decline in PDFF values, and LSM response was defined as a ≥1 stage decline from baseline.

Results

A total of 602 MASLD patients were enrolled. Of the 303 patients with a 24-week MRI-PDFF response and complete follow-up of 48 weeks, the rate of loss of MRI-PDFF response was 29.4%, and multivariable logistic regression analyses showed that 24-week insulin resistance (IR), still regular exercise and caloric restriction after 24 weeks, and the relative decline in LFC were risk factors for loss of MRI-PDFF response. Loss of LSM response at 48 weeks occurred in 15.9% of patients, and multivariable analysis confirmed 24-week serum total bile acid (TBA) levels and the relative decline in TBA from baseline as independent predictors. No significant association was found at 48 weeks between loss of MRI-PDFF response and loss of LSM response.

Conclusions

MASLD patients with IR and high TBA levels are at higher risks of subsequent diminished sustained improvements of steatosis and fibrosis, respectively.

CT Quantitation and Prediction of the Risk of Type 2 Diabetes Mellitus in Non-Obese Patients with Pancreatic Fatty Infiltration

Purpose

To examine the risk of type 2 diabetes mellitus in non-obese patients with pancreatic fatty infiltration through abdominal computed tomography (CT) quantitation.

Patients and Methods

We carried out a retrospective analysis of abdominal CT and inpatient medical records of 238 inpatients from July 2019 to April 2021. The patients were divided into a normal non-obese group (BMI < 25, n = 135) and diabetic non-obese group (BMI < 25, n = 103). Abdominal CT-related parameters included body width; mean CT values of the pancreas, liver, and spleen; difference between pancreas and spleen CT values (P-S); pancreas-to-spleen attenuation ratio (P/S); and liver-to-spleen attenuation ratio (L/S). Logistic regression was used to estimate the risk factors for comorbid diabetes in a non-obese population.

Results

The P-values of the pancreas CT value, P-S, P/S, body width, and L/S were all <0.05 and correlated to comorbid diabetes in non-obese patients. Worsening pancreatic fatty infiltration increased the risk of developing diabetes. Using a P/S of 1.0 as reference, every successive decrease in this ratio by 0.1 increases patient risk by 3.981, 4.452, 6.037, and 12.937 times.

Conclusion

The risk of developing type 2 diabetes mellitus in non-obese patients increases with the degree of pancreatic fatty infiltration as assessed by CT.

Phospholipid metabolism-related genotypes of PLA2R1 and CERS4 contribute to nonobese MASLD

BACKGROUND

Abnormal phospholipid metabolism is linked to metabolic dysfunction-associated steatotic liver disease (MASLD) development and progression. We aimed to clarify whether genetic variants of phospholipid metabolism modify these relationships.

METHODS

This case-control study consecutively recruited 600 patients who underwent MRI-based proton density fat fraction examination (240 participants with serum metabonomics analysis, 128 biopsy-proven cases) as 3 groups: healthy control, nonobese MASLD, and obese MASLD, (n = 200 cases each). Ten variants of phospholipid metabolism-related genes [phospholipase A2 Group VII rs1805018, rs76863441, rs1421378, and rs1051931; phospholipase A2 receptor 1 (PLA2R1) rs35771982, rs3828323, and rs3749117; paraoxonase-1 rs662 and rs854560; and ceramide synthase 4 (CERS4) rs17160348)] were genotyped using SNaPshot.

RESULTS

The T-allele of CERS4 rs17160348 was associated with a higher risk of both obese and nonobese MASLD (OR: 1.95, 95% CI: 1.20-3.15; OR: 1.76, 95% CI: 1.08-2.86, respectively). PLA2R1 rs35771982-allele is a risk factor for nonobese MASLD (OR: 1.66, 95% CI: 1.11-1.24), moderate-to-severe steatosis (OR: 3.24, 95% CI: 1.96-6.22), and steatohepatitis (OR: 2.61, 95% CI: 1.15-3.87), while the paraoxonase-1 rs854560 T-allele (OR: 0.50, 95% CI: 0.26-0.97) and PLA2R1 rs3749117 C-allele (OR: 1.70, 95% CI: 1.14-2.52) are closely related to obese MASLD. After adjusting for sphingomyelin level, the effect of the PLA2R1 rs35771982CC allele on MASLD was attenuated. Furthermore, similar effects on the association between the CERS4 rs17160348 C allele and MASLD were observed for phosphatidylcholine, phosphatidic acid, sphingomyelin, and phosphatidylinositol.

CONCLUSIONS

The mutations in PLA2R1 rs35771982 and CERS4 rs17160348 presented detrimental impact on the risk of occurrence and disease severity in nonobese MASLD through altered phospholipid metabolism.

Restoring skeletal muscle mass as an independent determinant of liver fat deposition improvement in MAFLD

AIMS

Cross-sectional studies have demonstrated the association of skeletal muscle mass with metabolic-associated fatty liver disease (MAFLD), while longitudinal data are scarce. We aimed to explore the impact of changes in relative skeletal muscle mass on the MAFLD treatment response.

METHODS

MAFLD patients undergoing magnetic resonance imaging-based proton density fat fraction for liver fat content (LFC) assessments and bioelectrical impedance analysis before and after treatment (orlistat, meal replacement, lifestyle modifications) were enrolled. Appendicular muscle mass (ASM) was adjusted by weight (ASM/W).

RESULTS

Overall, 256 participants were recruited and divided into two groups: with an ASM/W increase (n=166) and without an ASM/W increase (n=90). There was a great reduction in LFC in the group with an ASM/W increase (16.9% versus 8.2%, P < 0.001). However, the change in LFC in the group without an ASM/W increase showed no significant difference (12.5% versus 15.0%, P > 0.05). △ASM/W Follow-up-Baseline [odds ratio (OR)=1.48, 95% confidence interval (CI) 1.05-2.07, P = 0.024] and △total fat mass (OR=1.45, 95% CI 1.12-1.87, P = 0.004) were independent predictors for steatosis improvement (relative reduction of LFC ≥ 30%). The subgroup analysis showed that, despite without weight loss, decrease in HOMA-IR (OR=6.21, 95% CI 1.28-30.13, P=0.023), △total fat mass Baseline -Follow-up (OR=3.48, 95% CI 1.95-6.21, P <0.001 and △ASM/W Follow-up-Baseline (OR=2.13, 95% CI 1.12-4.05, P=0.022) independently predicted steatosis improvement.

CONCLUSIONS

ASM/W increase and loss of total fat mass benefit the resolution of liver steatosis, independent of weight loss for MAFLD.

Assessment of correlation between conventional anthropometric and imaging-derived measures of body fat composition: a systematic literature review and meta-analysis of observational studies

BACKGROUND

In studies of the association of adiposity with disease risk, widely used anthropometric measures of adiposity (e.g. body-mass-index [BMI], waist circumference [WC], waist-hip ratio [WHR]) are simple and inexpensive to implement at scale. In contrast, imaging-based techniques (e.g. magnetic resonance imaging [MRI] and dual x-ray absorptiometry [DXA]) are expensive and labour intensive, but can provide more accurate quantification of body fat composition. There is, however, limited evidence about the relationship between conventional and imaging-derived measures of adiposity.

METHODS

We searched Scopus and Web of Science for published reports in English of conventional versus imaging-derived measurements of adiposity. We identified 42 articles (MRI = 22; DXA = 20) that met selection criteria, involving 42,556 (MRI = 15,130; DXA = 27,426) individuals recruited from community or hospital settings. Study-specific correlation coefficients (r) were transformed using Fisher's Z transformation, and meta-analysed to yield weighted average correlations, both overall and by ancestry, sex and age, where feasible. Publication bias was investigated using funnel plots and Egger's test.

RESULTS

Overall, 98% of participants were 18 + years old, 85% male and 95% White. BMI and WC were most strongly correlated with imaging-derived total abdominal (MRI-derived: r = 0.88-; DXA-derived: 0.50-0.86) and subcutaneous abdominal fat (MRI-derived: 0.83-0.85), but were less strongly correlated with visceral abdominal fat (MRI-derived: 0.76-0.79; DXA-derived: 0.80) and with DXA-derived %body fat (0.76). WHR was, at best, strongly correlated with imaging-derived total abdominal (MRI-derived: 0.60; DXA-derived: 0.13), and visceral abdominal fat (MRI-derived: 0.67; DXA-derived: 0.65), and moderately with subcutaneous abdominal (MRI-derived: 0.54), and with DXA-derived %body fat (0.58). All conventional adiposity measures were at best moderately correlated with hepatic fat (MRI-derived: 0.36-0.43). In general, correlations were stronger in women than in men, in Whites than in non-Whites, and in those aged 18 + years.

CONCLUSIONS

In this meta-analysis, BMI and WC, but not WHR, were very strongly correlated with imaging-derived total and subcutaneous abdominal fat. By comparison, all three measures were moderately or strongly correlated with imaging-based visceral abdominal fat, with WC showing the greatest correlation. No anthropometric measure was substantially correlated with hepatic fat. Further larger studies are needed to compare these measures within the same study population, and to assess their relevance for disease risks in diverse populations.

A Comparative Study of Ultrasound Attenuation Imaging, Controlled Attenuation Parameters, and Magnetic Resonance Spectroscopy for the Detection of Hepatic Steatosis

OBJECTIVES

To investigate the methodology and clinical application of ultrasound attenuation imaging (ATI) and comparative analyze the diagnostic performance of ATI and controlled attenuation parameters (CAP) for detecting and grading hepatic steatosis.

METHODS

A total of 159 patients with NAFLD were prospectively enrolled. CAP and ATI examinations were performed within a week before proton magnetic resonance spectroscopy (¹ H-MRS). Ten liver attenuation coefficient (AC) measurements by ATI were obtained in each patient. The interclass correlation coefficients (ICCs) of the intraobserver consistencies and the ICCs between the median of the first two through the first nine measurements and all 10 measurements were calculated. The correlations between ¹ H-MRS, CAP, biological data, and ATI were evaluated. The significant factors associated with ATI and the diagnostic performance of ATI and CAP for detecting hepatic steatosis was evaluated.

RESULTS

The median value of AC for detecting hepatic steatosis was 0.831 dB/cm/MHz. For the intraobserver consistency of ATI, the ICC was 0.931. Compared with 10 measurements, a minimum of four ATI measurements was required. The correlation of AC with hepatic fat fraction (HFF) was significantly higher than that of CAP (0.603 vs 0.326, P = .0015). The HFF and triglyceride (TG) were the significant factors for the ATI. The area under the receiver operating characteristics (ROC) curves of ATI and CAP were 0.939 and 0.788 for detecting ≥10% hepatic steatosis; 0.751 and 0.572 for detecting >33% hepatic steatosis. The cutoff values of ATI and CAP were 0.697 dB/cm/MHz and 310 dB/m for detecting ≥10% hepatic steatosis; 0.793 dB/cm/MHz and 328 dB/m for detecting >33% hepatic steatosis. The sensitivity of ATI and CAP were 85.92% and 52.11% for detecting ≥10% hepatic steatosis; 87.50% and 82.14% for detecting >33% hepatic steatosis. The specificity of ATI and CAP were 94.12% and 100% for detecting ≥10% hepatic steatosis; 54.37% and 43.69% for detecting >33% hepatic steatosis.

CONCLUSIONS

ATI technology showed excellent intraobserver consistency and the optimal minimum number of ATI measurements was 4. ATI is a promising noninvasive, quantitative and convenient tool for assessing hepatic steatosis.

Metabolomics to identify fingerprints of carotid atherosclerosis in nonobese metabolic dysfunction-associated fatty liver disease

BACKGROUND/AIMS

Nonobese metabolic dysfunction-associated fatty liver disease (MAFLD) is paradoxically associated with improved metabolic and pathological features at diagnosis but similar cardiovascular diseases (CVD) prognosis to obese MAFLD. We aimed to utilize the metabolomics to identify the potential metabolite profiles accounting for this phenomenon.

METHODS

This prospective multicenter cross-sectional study was conducted in China enrolling derivation and validation cohorts. Liquid chromatography coupled with mass spectrometry and gas chromatography-mass spectrometry were applied to perform a metabolomics measurement.

RESULTS

The study involved 120 MAFLD patients and 60 non-MAFLD controls in the derivation cohort. Controls were divided into two groups according to the presence of carotid atherosclerosis (CAS). The MAFLD group was further divided into nonobese MAFLD with/without CAS groups and obese MAFLD with/without CAS groups. Fifty-six metabolites were statistically significant for discriminating the six groups. Among the top 10 metabolites related to CAS in nonobese MAFLD, only phosphatidylethanolamine (PE 20:2/16:0), phosphatidylglycerol (PG 18:0/20:4) and de novo lipogenesis (16:0/18:2n-6) achieved significant areas under the ROC curve (AUCs, 0.67, p = 0.03; 0.79, p = 0.02; 0.63, p = 0.03, respectively). The combination of these three metabolites and liver stiffness achieved a significantly higher AUC (0.92, p < 0.01). In obese MAFLD patients, cystine was found to be significant with an AUC of 0.69 (p = 0.015), followed by sphingomyelin (SM 16:1/18:1) (0.71, p = 0.004) and de novo lipogenesis (16:0/18:2n-6) (0.73, p = 0.004). The combination of these three metabolites, liver fat content and age attained a significantly higher AUC of 0.91 (p < 0.001). The AUCs of these metabolites remained highly significant in the independent validation cohorts involving 200 MAFLD patients and 90 controls.

CONCLUSIONS

Diagnostic models combining different metabolites according to BMI categories could raise the accuracy of identifying subclinical CAS. Trial registration The study protocol was approved by the local ethics committee and all the participants have provided written informed consent (Approval number: [2014] No. 112, registered at the Chinese Clinical Trial Registry, ChiCTR-ChiCTR2000034197).

The Correlation between Type 2 Diabetes and Fat Fraction in Liver and Pancreas: A Study using MR Dixon Technique

Objective

The increased obesity results in ectopic fat deposits in liver and pancreas, which will affect insulin resistance and elevated plasma glucose with type 2 diabetes. To assess the relationship between obesity and ectopic fat deposits and diabetes, this study used the MR Dixon method for the quantification of liver and pancreas fat fraction (FF) in type 2 diabetes mellitus (T2DM) patients and healthy controls.

Methods

The FF of whole liver (FFWL) and pancreas (FFWP), the maximum diameters of the pancreas, the abdominal subcutaneous adipose area (SAT), the visceral adipose tissue area (VAT), and the total abdominal adipose tissue area (TAT) were measured for 157 subjects using the MR Dixon data. Four groups were established on the basis of BMI value. For statistics, intra- and intergroup comparisons were made by employing independent sample t-test.

Results

FFWL, FFWP, and VAT varied significantly between T2DM (BMI < 25) and control group (BMI < 25), T2DM (BMI ≥ 25) and control group (BMI ≥ 25), T2DM (BMI < 25) and T2DM (BMI ≥ 25) (all P < 0.05). The FF of pancreas tail, SAT, and TAT varied significantly between control group (BMI < 25) and control group (BMI ≥ 25) (P < 0.05). FFWP and the FF of pancreas tail varied significantly between T2DM and normal volunteers (P < 0.05), with normal or mild liver fat content.

Conclusion

The tissue FF, which has a close relationship with T2DM, can be assessed by the MR Dixon technique. T2DM patients should pay attention to tissue fat content regardless of BMI values.

Discrepancies between Nonalcoholic and Metabolic-associated Fatty Liver Disease by Multiple Steatosis Assessment

BACKGROUND AND AIMS

The redefinition of metabolic-associated fatty liver disease (MAFLD) from nonalcoholic fatty liver disease (NAFLD) has caused a revolution in clinical practice, and the characteristics of patients with steatosis but not MAFLD remain unclear. The aims were to compare the diagnosis rate of MAFLD in NAFLD using different steatosis methods and explore the features of non-MAFLD-NAFLD and MAFLD-non-NAFLD.

METHODS

A cross-sectional study enrolling consecutive individuals was conducted at three medical centers in southern China from January 2015 to September 2020. Steatosis was evaluated by liver biopsy or magnetic resonance imaging-based proton density fat fraction (MRI-PDFF), ultrasound, controlled attenuation parameter (CAP), and fatty liver index (FLI). Fibrosis was assessed by the NAFLD fibrosis score, transient elastography, or shear wave elastography.

RESULTS

The study enrolled 14,985 Chinese adults. The agreement of MAFLD and NAFLD diagnoses were 83% for FLI, 95% for ultrasound, 94% for both CAP and MRI-PDFF, and 95% for liver biopsy. The body mass index, blood pressure and lipid levels among non-MAFLD-NAFLD patients were similar metabolic parameters (p>0.05 for all), but not the alanine aminotransferase and the proportion of patients with insulin resistance, which were significantly higher in non-MAFLD-NAFLD with significant fibrosis.

CONCLUSIONS

The new MAFLD definition ruled out 5-17% of NAFLD cases. NAFLD and MAFLD-NAFLD involved more severe metabolic abnormalities than MAFLD and MAFLD-non-NAFLD. Non-MAFLD-NAFLD patients with significant fibrosis had more severe liver injury and increased glycemic dysregulation within the normal range. Attention should be paid to its progression.

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.

The Ability of Lipoprotein (a) Level to Predict Early Carotid Atherosclerosis Is Impaired in Patients With Advanced Liver Fibrosis Related to Metabolic-Associated Fatty Liver Disease

INTRODUCTION

Hepatic fibrosis reduces the serum level of lipoprotein (a) (Lp(a)) and may affect its accuracy in cardiovascular disease prediction of metabolic-associated fatty liver disease (MAFLD). We aimed to estimate the association between Lp(a) levels and the risk of carotid atherosclerosis in MAFLD patients with advanced fibrosis.

METHODS

This was a cross-sectional study enrolling 4,348 consecutive individuals (1,346 patients with MAFLD and 3,002 non-MAFLD patients) who were admitted to the First Affiliated Hospital, Sun Yat-sen University, and underwent abdominal and carotid ultrasonography from 2015 to 2021. Lp(a) levels, liver biochemical markers, metabolic indices, and anthropometric parameters were measured. Liver fat content and fibrosis severity were assessed by MRI-PDFF, using the NAFLD fibrosis score (NFS) and liver stiffness measurement (LSM) of two-dimensional shear wave elastography, respectively.

RESULTS

There was an L-shaped relationship between Lp(a) levels and LSMs in patients with MAFLD, and Lp(a) levels had a different relationship with liver fat content in MAFLD patients with F1-2 versus those with F3-4. Non-MAFLD patients had higher levels of Lp(a) than MAFLD patients with or without advanced fibrosis (both P < 0.05). Lp(a) levels and degree of liver fibrosis were both positively correlated with carotid atherosclerosis in patients with MAFLD. Lp(a) levels performed well on carotid atherosclerosis risk prediction for non-MAFLD patients with an area under the curve (AUC) of 0.819, which was significantly better than the carotid atherosclerosis risk prediction for MAFLD patients with NFS ≤ -1.836 (AUC: 0.781), NFS > -1.836 (AUC: 0.692), and LSM ≥ 9.0 kPa (AUC: 0.635) (all P < 0.05).

DISCUSSION

Advanced liver fibrosis significantly reduces the predictive value of Lp(a) levels for the risk of carotid atherosclerosis in patients with MAFLD.

Vitamin D Status Presents Different Relationships with Severity in Metabolic-Associated Fatty Liver Disease Patients with or without Hepatitis B Infection

Whether the associations between serum vitamin D (VitD) and metabolic-associated fatty liver disease (MAFLD) vary with chronic hepatitis B (CHB) infection has not been well established. This study aims to investigate the relationships between serum VitD and metabolism, liver fat content (LFC) and fibrosis among MAFLD patients with and without CHB. Consecutive subjects (healthy controls: 360, CHB: 684, MAFLD: 521, CHB with MAFLD: 206) were prospectively enrolled between January 2015 and December 2021. Anthropometric, laboratory, imaging, and histological evaluations were conducted, with LFC measured via magnetic resonance imaging-based proton density fat fraction (MRI-PDFF). Serum VitD levels were lower in MAFLD patients than in healthy controls and patients with CHB alone or overlapping with MAFLD (24.4 ± 8.1 vs. 29.0 ± 9.5 vs. 27.4 ± 9.6 vs. 26.8 ± 8.4 ng/mL respectively; p < 0.001 in one-way ANOVA test). After adjusting for confounding factors, including season, hypersensitive C-reactive protein, insulin resistance, liver stiffness measurements, sun exposure, exercise and dietary intake, multivariate linear regression analysis revealed that VitD remained significantly negatively correlated with LFC in MAFLD patients (β = −0.38, p < 0.001), but not in CHB with MAFLD patients. Moreover, quantile regression models also demonstrated that lower VitD tertiles were inversely associated with the risk of insulin resistance and moderate−severe steatosis in the MAFLD group (p for trend <0.05) but not in the MAFLD with CHB group. VitD deficiency was associated with the severity of metabolic abnormalities and steatosis independent of lifestyle factors in MAFLD-alone subjects but not in MAFLD with CHB subjects.

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

Background

The consistency in steatosis grading between magnetic resonance imaging-based proton density fat fraction (MRI-PDFF) and controlled attenuation parameter (CAP) before and after treatment remains unclear. This study aimed to compare the diagnostic accuracy of steatosis grading between MRI-PDFF and CAP using liver biopsy as standard and to evaluate the value of monitoring changes in steatosis grading with CAP during follow-up utilizing MRI-PDFF as a reference.

Methods

Consecutive patients from a biopsy cohort and a randomized controlled trial were included in this study and classified into 3 groups (the biopsy, orlistat treatment, and routine treatment subgroups). Hepatic steatosis was measured via MRI-PDFF and CAP at baseline and at the 6th month; the accuracy and cutoffs were assessed in the liver biopsy cohort at baseline.

Results

A total of 209 consecutive patients were enrolled. MRI-PDFF and CAP showed comparable diagnostic accuracy for detecting pathological steatosis [⩾S1, area under the receiver operating characteristic curve (AUC) = 0.984 and 0.972, respectively]; in contrast, CAP presented significantly lower AUCs in grades S2-3 and S3 (0.820 and 0.815, respectively). The CAP values correlated well with the MRI-PDFF values at baseline and at the 6th month (r = 0.809 and 0.762, respectively, both p < 0.001), whereas a moderate correlation in their changes (r = 0.612 and 0.524 for moderate-severe and mild steatosis, respectively; both p < 0.001) was observed. The AUC of CAP change was obtained to predict MRI-PDFF changes of ⩾5% and ⩾10% (0.685 and 0.704, p < 0.001 and p = 0.001, respectively). The diagnostic agreement of steatosis grade changes between MRI-PDFF and CAP was weak (κ = 0.181, p = 0.001).

Conclusions

CAP has decreased value for the initial screening of moderate-severe steatosis and is limited in monitoring changes in steatosis during treatment. The confirmation of steatosis grading with MRI-PDFF remains necessary.

Distinct Dose-Dependent Association of Free Fatty Acids with Diabetes Development in Nonalcoholic Fatty Liver Disease Patients

BACKGROUND

Excessive delivery of free fatty acids (FFAs) to the liver promotes steatosis and insulin resistance (IR), with IR defined as reduced glucose uptake, glycogen synthesis and anti-lipolysis stimulated by normal insulin levels. Whether the associations between FFAs and diabetes development differ between patients with and without nonalcoholic fatty liver disease (NAFLD) remains unclear.

METHODS

Consecutive subjects (2,220 NAFLD subjects and 1,790 non-NAFLD subjects according to ultrasound imaging) were enrolled from the First Affiliated Hospital of Sun Yat-sen University between 2009 and 2019. The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated.

RESULTS

There was an approximate J-shaped relationship between FFA levels and HOMA-IR in the NAFLD group. Higher FFA concentration quartiles were associated with higher risks of IR (odds ratio [OR], 9.24; 95% confidence interval [CI], 6.43 to 13.36), prediabetes (OR, 10.48; 95% CI, 5.66 to 19.39), and type 2 diabetes mellitus (T2DM; OR, 19.43; 95% CI, 12.75 to 29.81) in the NAFLD group but not in the non-NAFLD group. The cut-off points for the FFA levels increased in a stepwise manner in discriminating IR, prediabetes and T2DM (573, 697, and 715 μmol/L) in the NAFLD group but not in non-NAFLD individuals.

CONCLUSION

A distinct dose-dependent relationship of FFA levels was found with IR, prediabetes and T2DM in NAFLD patients. Screening serum FFA levels in NAFLD patients would be valuable in preventing diabetes development.

Varied Relationship of Lipid and Lipoprotein Profiles to Liver Fat Content in Phenotypes of Metabolic Associated Fatty Liver Disease

BACKGROUND

Progressive overloads of intrahepatic triglycerides are related to metabolic dysregulation of multiple lipid and lipoprotein profiles, but whether similar dose effects are found in each subtype of metabolic associated fatty liver disease (MAFLD) remains unclear. We aimed to characterize the lipid profiles associated with liver fat content (LFC) in MAFLD patients who were overweight, lean/normal weight, or had diabetes.

METHODS

We conducted a cross-sectional study enrolling 1,182 consecutive participants (144 non-MAFLD and 1,038 MAFLD) who underwent MRI proton density fat fraction measurement (MRI-PDFF) from 2011 to 2020. Lipid and apolipoprotein profiles, free fatty acid (FFA), liver and metabolism parameters, and anthropometric measurements were also assessed.

RESULTS

MAFLD patients with type 2 diabetes or overweight/obesity had a higher proportion of abnormal lipid and lipoprotein profiles than those who were lean/normal weight. The degree of LFC had a positive correlation with total cholesterol, triglyceride, ApoB, and ApoE in patients with overweight/obesity and type 2 diabetes. In those with overweight/obesity, there were dose-response relationships between moderate-to-severe steatosis and total cholesterol, triglyceride, HDL-c, LDL-c, ApoB, ApoE, and Lp(a). A similar trend was observed for triglyceride in those with type 2 diabetes and for HDL-c in patients who were lean/normal weight (all p for trend <0.05). The combined model of relative lipid-related markers performed well in the prediction of moderate-to-severe steatosis (AUC: 0.762 for overweight/obesity; 0.742 for lean/normal weight).

CONCLUSION

LFC was associated with lipid profiles, including triglyceride, LDL-c, ApoB, ApoE, and FFA. These relationships were varied by the phenotype of MAFLD according to its diagnostic flow.

Visceral adiposity and liver fat as mediators of the association between cardiorespiratory fitness and plasma glucose-insulin homeostasis

Cardiorespiratory fitness (CRF) is positively associated with insulin sensitivity, whereas excessive levels of visceral adipose tissue (AT) and liver fat (LF) are both associated with insulin resistance and impaired plasma glucose-insulin homeostasis. To what extent levels of visceral AT and LF content contribute to the relationship between CRF and indices of plasma glucose-insulin homeostasis is uncertain. Our objective was to explore the interactions among CRF, visceral AT, and LF with glucose tolerance/insulin levels in asymptomatic and apparently healthy individuals. CRF was measured in 135 women and 177 men with a maximal treadmill graded exercise test. Indices of plasma glucose-insulin homeostasis were derived from a 3-h oral glucose tolerance test (OGTT) performed in the morning after a 12-h fast. Visceral AT levels and LF content were measured using magnetic resonance imaging and spectroscopy. For any given CRF level, women presented significantly lower visceral AT and LF than men as well as lower homeostasis model assessment of insulin resistance (HOMA-IR) and plasma glucose-insulin levels during the OGTT compared with men. In both sexes, there were significant negative correlations between CRF and HOMA-IR as well as glucose and insulin levels measured during the OGTT. Both glucose and insulin levels during the OGTT correlated positively with visceral AT and LF. In women and men, being in the top CRF tertile was associated with low levels of visceral AT and LF. Multivariable linear regression analyses suggested that visceral AT and LF were plausible mediators of the association between CRF and indices of plasma glucose-insulin homeostasis.

Early Predictors of Cardiovascular Disease Risk in Nonalcoholic Fatty Liver Disease: Non-obese Versus Obese Patients

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is regarded as a risk factor of cardiovascular disease (CVD). However, the association between non-obese NAFLD and CVD has not been well established.

AIM

We aimed to compare the CVD risk between non-obese and obese NAFLD patients, and explored the factors associated with subclinical atherosclerosis.

METHOD

Consecutive NAFLD patients estimated by magnetic resonance imaging-based proton density fat fraction (MRI-PDFF) were recruited. Liver fat content (LFC) and liver stiffness were measured with MRI-PDFF and shear wave elastography, respectively. CVD risk was estimated by atherosclerosis index (AI), carotid intima-media thickness, carotid plaque, and Framingham risk score (FRS).

RESULTS

This study included 543 NAFLD patients. The presence of carotid intima-media thickening and carotid plaque, FRS, and AI were comparable between non-obese and obese patients. Age increased per 10 years (OR 9.68; P < 0.001) and liver fibrosis (liver stiffness > 6.1 kPa, OR 4.42; P = 0.004) were significant factors associated with carotid intima-media thickening in non-obese patients, while age increased per 10 years (OR 2.02; P < 0.001), liver fibrosis (OR 2.18; P = 0.039), and LFC > 10% (OR 2.29; P = 0.021) were independent predictors in obese patients. Only elevated triglyceride was significantly associated with carotid plaque in non-obese patients (OR 2.42; P = 0.033), while age increased per 10 years (OR 1.77; P = 0.002) and LFC > 10% (OR 2.83; P = 0.019) were significant predictors in obese patients.

CONCLUSIONS

Liver stiffness and age were strongly predictive of subclinical atherosclerosis in all NAFLD, while LFC was an additional predictor in obese NAFLD patients. Our findings highlight that early CVD screening strategy should be established for NAFLD patients according to different BMIs.

Precise fibrosis staging with shear wave elastography in chronic hepatitis B depends on liver inflammation and steatosis

BACKGROUND

Two-dimensional shear wave elastography (2D-SWE) is the latest generation of ultrasound elastography for the non-invasive assessment of liver fibrosis in chronic hepatitis B (CHB). We aimed to identify confounders of 2D-SWE in fibrosis grading.

METHODS

A prospective cohort of 440 CHB patients (286 with liver biopsy and 154 with clinical decompensated cirrhosis) was consecutively enrolled from a clinical trial (registration number: ChiCTR-DCD-15006000) aimed at optimizing 2D-SWE assessments from 2015 to 2018. All patients underwent 2D-SWE examination, anthropometric measurement, and serum biomarker assessment. Steatosis was graded by the magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF).

RESULTS

Overall, the prevalence of incorrect fibrosis staging by 2D-SWE was 26.1% (n = 115), with 43.5% of patients under-staged and 56.5% over-staged. In multivariate analysis, the steatosis degree was an independent predictor of 2D-SWE discordance in the overall cohort, with moderate-severe steatosis for underestimation (odds ratio, [OR] = 4.3, 95% confidence interval [CI] 1.2-18.2, p = 0.049) and overestimation (OR = 8.2, 95% CI 2.9-23.5, p < 0.001), and mild steatosis for overestimation (OR = 3.7, 95% CI 1.5-9.0, p = 0.004). In patients with liver biopsy, both histological inflammation activity over 2 (OR = 5.0, 95% CI 2.0-25.3, p = 0.048) and moderate-severe steatosis (OR = 5.2, 95% CI 2.1-13.4, p < 0.001) were independent factors associated with discordance. For the risk of 2D-SWE mis-staging, a nomogram that integrated these confounders was established and the area under the receiver operating characteristic curve of the model was 0.861.

CONCLUSIONS

Steatosis and inflammation activities were confounders for 2D-SWE. The combination of these confounders could predict mis-staging risks of CHB-related fibrosis with 2D-SWE and may be valuable to decision-making on liver biopsy for fibrosis staging.

Different predictors of steatosis and fibrosis severity among lean, overweight and obese patients with nonalcoholic fatty liver disease

BACKGROUNDS

Non-obese nonalcoholic fatty liver disease (NAFLD) is paradoxically associated with improved metabolic and pathological features at diagnosis but worse prognosis relative to obese NAFLD.

AIM

To compare predictors of disease severity in NAFLD with different body mass index (BMI) categories.

METHODS

All 1509 consecutive NAFLD patients were classified as lean (20.2%), overweight (23.1%) and obese (56.7%). Liver fat content (LFC) and fibrosis were estimated with magnetic resonance imaging-based proton density fat fraction and shear wave elastography respectively.

RESULTS

Lipid profiles and uric acid (UA) were significantly increased in parallel with BMI categories (pairwise comparison P < 0.001), but insulin resistance (IR) was significantly different between the non-obese and obese groups. For LFC ≥ 10%, increased waist circumference (WC) was an independent predictor in all groups, while UA elevation (P = 0.02) was predictive in the overweight patients, but BMI ≥ 28 kg/m² (P = 0.029) and IR (P = 0.026) were significant in the obese patients. For fibrosis, alanine aminotransferase (ALT) > 40 U/L (P = 0.031), increased WC (P = 0.012) and BMI ≥ 28 kg/m² (P < 0.001) plus ALT > 40 U/L (P = 0.007) were predictors in the lean, overweight and obese patients, respectively.

CONCLUSIONS

WC was strongly predictive of disease severity in all NAFLD, while UA and BMI plus IR were additional predictors in the overweight and obese NAFLD respectively. Individualized screening strategies should be established for NAFLD according to different BMIs.

Effect of orlistat on liver fat content in patients with nonalcoholic fatty liver disease with obesity: assessment using magnetic resonance imaging-derived proton density fat fraction

BACKGROUND

The liver effect of orlistat as a weight control treatment in patients with nonalcoholic fatty liver disease (NAFLD) with obesity remains undetermined. This study quantified liver fat improvement by orlistat in a Chinese cohort with NAFLD accompanied by obesity, diagnosed by a lower body mass index threshold than that for White patients.

MATERIALS AND METHODS

We conducted a parallel-group, open-label, 24-week, randomized clinical trial registered at the Chinese Clinical Trial Registry (ChiCTR-IPR-17012258). Obese participants with NAFLD were randomized 1:1.5 to the intervention group with orlistat or conventional care. Liver fat quantification was assessed by magnetic resonance imaging-based proton density fat fraction with Dixon sequence.

RESULTS

Overall, 170 (n = 68, orlistat 120 mg three times/day and n = 102, conventional therapy) and 130 patients with NAFLD (n = 56, orlistat and n = 74, conventional therapy) were included for intention-to-treat (ITT) and per-protocol (PP) analysis, respectively. Orlistat reduced liver fat content to a greater degree than conventional care [-5.45% versus -1.96%, p < 0.001 (ITT analysis) and -6.66% versus -2.68%, p < 0.001 (PP analysis)]. The 6-month rate of decrease in steatosis grades was higher in the orlistat group [45.6% versus 22.5% (ITT analysis), 57.4% versus 30.3% (PP analysis), both p < 0.001]. Multivariate logistic regression analysis identified orlistat treatment [odds ratio (OR) = 2.4; 95% confidence interval (CI) 1.1-5.6, p = 0.036] as an independent predictor of steatosis improvement. Among patients with orlistat therapy, weight loss (OR = 1.2, 95% CI 1.1-1.4, p = 0.040) and severe steatosis (OR = 6.7, 95% CI: 1.1-40.3, p = 0.03) remained predictive of steatosis improvement.

CONCLUSIONS

Orlistat can effectively promote steatosis improvement and may serve as a treatment option for controlling NAFLD.

CHINESE CLINICAL TRIAL REGISTRY IDENTIFIER

ChiCTR-IPR-17012258.

Quantitative magnetic resonance imaging evaluation of hepatic fat content with iron deposition: will it be disturbed?

Objective

To explore noninvasive assessment of liver fat content with iron deposition using magnetic resonance (MR) quantitative technology.

Methods

A water–fat phantom with iron deposition containing 63 vials with predetermined fat percentages and iron concentrations was constructed. Thirty-three patients underwent fat quantitative MR examinations. The fat fraction (FF) was determined by three Dixon techniques. Pathological evaluation findings and the steatosis area rate (SAR) were used as the gold standards.

Results

FF_IOP and FF_LAVA-Flex significantly differed from FF_TEST for iron concentrations of 1 to 30 µg/mL and fat components of 10% to 80%. Using the three Dixon techniques, FF_IOP was 15.76% ± 6.98%, FF_LAVA-Flex was 16.71% ± 6.77%, and FF_{IDEAL IQ} was 13.18% ± 6.42% in patients without liver cirrhosis; these values in patients with liver cirrhosis were 20.35% ± 6.11%, 20.89% ± 8.49%, and 12.86% ± 4.00%, respectively. The SAR in patients without and with liver cirrhosis was 11.31% ± 5.89% and 9.84% ± 4.17%, respectively. There were significant positive correlations between FF_{IDEAL IQ} and SAR with or without liver cirrhosis.

Conclusion

Iron deposition must be considered when using quantitative MR techniques to evaluate the hepatic fat content. Compared with the IOP and LAVA-Flex techniques, the IDEAL IQ technique has more stability and accuracy in measurement of the hepatic fat content, free from iron deposition.

Insulin resistance exhibits varied metabolic abnormalities in nonalcoholic fatty liver disease, chronic hepatitis B and the combination of the two: a cross-sectional study

BACKGROUND

Insulin resistance (IR) related metabolic disorders are associated with a worse prognosis of chronic hepatitis B virus (CHB) infection or nonalcoholic fatty liver disease (NAFLD). However, the relationships among CHB, steatosis, IR and metabolic factors remain controversial. The study aims to evaluate the impact of insulin resistance severity on metabolic profiles in patients with CHB, NAFLD and the coincidence of the two.

METHODS

We conducted a cross-sectional study between January 2011 and December 2018 that included 2768 consecutive Chinese subjects (healthy controls: 667, CHB: 970, NAFLD: 878, CHB with NAFLD: 253). IR was determined with the homeostasis model assessment for insulin resistance (HOMA-IR). Metabolic measures included fasting serum insulin, glucose, lipid profiles and uric acid.

RESULTS

The prevalence of IR was increased in CHB with NAFLD subjects compared with that in control subjects or subjects with CHB or NAFLD alone (41.5% vs 2.9%/11.9%/36.9%, respectively; P < 0.001). Within NAFLD and CHB with NAFLD group, the frequency of metabolic syndrome, hypertension and hyperuricemia increased as the HOMA-IR category increased (P for trend < 0.05). A higher risk for total cholesterol, low-density lipoprotein cholesterol and elevated alanine transaminase was observed with IR in the CHB with NAFLD group compared with that in the other groups, while no stepwise increase in hypertriglyceridemia was found in HOMA-IR in the CHB with NAFLD group.

CONCLUSION

Insulin resistance is highly prevalent in patients with CHB combined with NAFLD, and the increased metabolic risk, rather than hypertriglyceridemia, is driven by IR in CHB combined with NAFLD.

An Exercise Intervention to Unravel the Mechanisms Underlying Insulin Resistance in a Cohort of Black South African Women: Protocol for a Randomized Controlled Trial and Baseline Characteristics of Participants

Background

The pathogenesis of type 2 diabetes (T2D) in black African women is complex and differs from that in their white counterparts. However, earlier studies have been cross-sectional and provide little insight into the causal pathways. Exercise training is consistently used as a model to examine the mechanisms underlying insulin resistance and risk for T2D.

Objective

The objective of the study was to examine the mechanisms underlying the changes in insulin sensitivity and secretion in response to a 12-week exercise intervention in obese black South African (SA) women.

Methods

A total of 45 obese (body mass index, BMI: 30-40 kg/m²) black SA women were randomized into a control (n=22) or experimental (exercise; n=23) group. The exercise group completed 12 weeks of supervised combined aerobic and resistance training (40-60 min, 4 days/week), while the control group maintained their typical physical activity patterns, and both groups were requested not to change their dietary patterns. Before and following the 12-week intervention period, insulin sensitivity and secretion (frequently sampled intravenous glucose tolerance test) and its primary and secondary determinants were measured. Dietary intake, sleep quality and quantity, physical activity, and sedentary behaviors were measured every 4 weeks.

Results

The final sample included 20 exercise and 15 control participants. Baseline sociodemographics, cardiorespiratory fitness, anthropometry, cardiometabolic risk factors, physical activity, and diet did not differ between the groups (P>.05).

Conclusions

The study describes a research protocol for an exercise intervention to understand the mechanisms underlying insulin sensitivity and secretion in obese black SA women and aims to identify causal pathways underlying the high prevalence of insulin resistance and risk for T2D in black SA women, targeting specific areas for therapeutic intervention.

Trial Registration

Pan African Clinical Trial Registry PACTR201711002789113; http://www.pactr.org/ATMWeb/ appmanager/atm/atmregistry?_nfpb=true&_pageLabel=portals_app_atmregistry_portal_page_13 (Archived by WebCite at http://www.webcitation.org/6xLEFqKr0)

Non-Invasive Electrical Impedance Tomography for Multi-Scale Detection of Liver Fat Content

Introduction: Obesity is associated with an increased risk of nonalcoholic fatty liver disease (NAFLD). While Magnetic Resonance Imaging (MRI) is a non-invasive gold standard to detect fatty liver, we demonstrate a low-cost and portable electrical impedance tomography (EIT) approach with circumferential abdominal electrodes for liver conductivity measurements. Methods and Results: A finite element model (FEM) was established to simulate decremental liver conductivity in response to incremental liver lipid content. To validate the FEM simulation, we performed EIT imaging on an ex vivo porcine liver in a non-conductive tank with 32 circumferentially-embedded electrodes, demonstrating a high-resolution output given a priori information on location and geometry. To further examine EIT capacity in fatty liver detection, we performed EIT measurements in age- and gender-matched New Zealand White rabbits (3 on normal, 3 on high-fat diets). Liver conductivity values were significantly distinct following the high-fat diet (p = 0.003 vs. normal diet, n=3), accompanied by histopathological evidence of hepatic fat accumulation. We further assessed EIT imaging in human subjects with MRI quantification for fat volume fraction based on Dixon procedures, demonstrating average liver conductivity of 0.331 S/m for subjects with low Body-Mass Index (BMI < 25 kg/m²) and 0.286 S/m for high BMI (> 25 kg/m²). Conclusion: We provide both the theoretical and experimental framework for a multi-scale EIT strategy to detect liver lipid content. Our preliminary studies pave the way to enhance the spatial resolution of EIT as a marker for fatty liver disease and metabolic syndrome.

Angiopoietin-like protein 8/betatrophin correlates with hepatocellular lipid content independent of insulin resistance in non-alcoholic fatty liver disease patients

Aims/Introduction

To explore angiopoietin‐like protein 8 (ANGPTL‐8) levels, and its association with hepatocellular lipid content (HCL) and insulin resistance in patients with different extents of non‐alcoholic fatty liver disease (NAFLD).

Materials and Methods

In 48 adults were recruited, of which 12 had no NAFLD (HCL < 5.5%; group 1), 18 had mild NAFLD (5.5% ≤ HCL < 10.0%; group 2) and 18 had moderate‐to‐severe NAFLD (HCL ≥ 10.0%; group 3). The peripheral insulin sensitivity of all participants was monitored by a hyperinsulinemic‐euglycemic clamp (M value), as well as the magnetic resonance image of HCL. Serum ANGPTL‐8, blood glucose levels and lipid profiles were also recorded in the study.

Results

Group 3 had a worse metabolic profile, and had the highest ANGPTL‐8 level (1,129 ± 351 pg/mL vs 742 ± 252 pg/mL, 765 ± 301 pg/mL, P = 0.001) compared with those in group 1 and group 2. In all metabolic profiles, HCL positively correlated the strongest with ANGPTL‐8 (r = 0.436, P = 0.042). Multivariate stepwise linear regression analysis showed ANGPTL‐8 and alanine aminotransferase were independent determinants of HCL (P = 0.002, P < 0.001, respectively), and these two indexes explained 67.4% of the variation of HCL (P < 0.001).

Conclusions

ANGPTL‐8 was positively correlated with hepatocellular lipid content independent of obesity and insulin resistance, indicating that ANGPTL‐8 might be a new and important important predictor of the severity of NAFLD.

Magnetic Resonance Elastography and Other Magnetic Resonance Imaging Techniques in Chronic Liver Disease: Current Status and Future Directions

Recent advances in the noninvasive imaging of chronic liver disease have led to improvements in diagnosis, particularly with magnetic resonance imaging (MRI). A comprehensive evaluation of the liver may be performed with the quantification of the degree of hepatic steatosis, liver iron concentration, and liver fibrosis. In addition, MRI of the liver may be used to identify complications of cirrhosis, including portal hypertension, ascites, and the development of hepatocellular carcinoma. In this review article, we discuss the state of the art techniques in liver MRI, namely, magnetic resonance elastography, hepatobiliary phase MRI, and liver fat and iron quantification MRI. The use of these advanced techniques in the management of chronic liver diseases, including non-alcoholic fatty liver disease, will be elaborated.

Intrahepatic fat, abdominal adipose tissues, and metabolic state: magnetic resonance imaging study

BACKGROUND

Intrahepatic fat (IHF) is best known to associate with waist circumference (WC) and visceral adipose tissue (VAT), but its relation to abdominal subcutaneous adipose tissue is controversial. While IHF ≥ 5% dichotomously defines fatty liver, %IHF is rarely considered as a continuous variable that includes the normal range. In this study, we aimed to evaluate %IHF association with abdominal fat subdepots, pancreatic, and renal-sinus fats.

METHODS

We evaluated %IHF, abdominal fat subdepots, %pancreatic, and renal-sinus fats, among individuals with moderate abdominal obesity, using 3-Tesla magnetic resonance imaging.

RESULTS

Among 275 participants, %IHF widely ranged (0.01%-50.4%) and was lower in women (1.6%) than men (7.3%; P < .001). In an age, sex, and WC-adjusted models, VAT area (P < .006) was directly associated with %IHF, while superficial-subcutaneous adipose tissue proportion was inversely associated with %IHF (P < .006). In these models, renal-sinus fat was positively associated with %IHF (P = .005). In an age, sex, WC, and VAT-adjusted models, elevated liver enzymes, glycemic, lipid, and inflammatory biomarkers were associated with increased %IHF (P < .003 for all). In these models, the associations remained robust even within the normal range strata of IHF < 5% for triglycerides and chemerin (P ≤ .004 for all). For the diagnosis of fatty liver, the joint area under the curve of WC, alanine-aminotransferase, triglycerides/high-density lipoprotein cholesterol, and homeostasis model assessment of insulin resistance was 0.84(95% CI, 0.79-0.89).

CONCLUSIONS

Intrahepatic fat is differentially associated with abdominal fat subdepots. Intrahepatic-fat as a continuous variable could be predicted by specific traditional parameters, even within the current normal range, and partially independent of VAT.

Noninvasive fat quantification of the liver and pancreas may provide potential biomarkers of impaired glucose tolerance and type 2 diabetes

The aim of the study is to investigate if the fat content of the liver and pancreas may indicate impaired glucose tolerance (IGT) or type 2 diabetes mellitus (T2DM). A total of 83 subjects (34 men; aged 46.5 ± 13.5 years) were characterized as T2DM, IGT, or normal glucose tolerant (NGT). NGT individuals were stratified as <40 or ≥40 years. Standard laboratory tests were conducted for insulin resistance and β-cell dysfunction. The magnetic resonance imaging Dixon technique was used to determine fat distribution in the liver and pancreas. Correlations among liver and pancreatic fat volume fractions (LFVFs and PFVFs, respectively) and laboratory parameters were analyzed. Among the groups, fat distribution was consistent throughout sections of the liver and pancreas, and LFVFs closely correlated with PFVFs. LFVFs correlated more closely than PFVFs with insulin resistance and β-cell function. Both the LFVFs and PFVFs were the highest in the T2DM patients, less in the IGT, and least in the NGT; all differences were significant. The PFVFs of the NGT subjects ≥40 years were significantly higher than that of those <40 years. The fat content of the liver and pancreas, particularly the liver, may be a biomarker for IGT and T2DM.

MR-based assessment of body fat distribution and characteristics

The assessment of body fat distribution and characteristics using magnetic resonance (MR) methods has recently gained significant attention as it further extends our pathophysiological understanding of diseases including obesity, metabolic syndrome, or type 2 diabetes mellitus, and allows more detailed insights into treatment response and effects of lifestyle interventions. Therefore, the purpose of this study was to review the current literature on MR-based assessment of body fat distribution and characteristics. PubMed search was performed to identify relevant studies on the assessment of body fat distribution and characteristics using MR methods. T1-, T2-weighted MR Imaging (MRI), Magnetic Resonance Spectroscopy (MRS), and chemical shift-encoding based water-fat MRI have been successfully used for the assessment of body fat distribution and characteristics. The relationship of insulin resistance and serum lipids with abdominal adipose tissue (i.e. subcutaneous and visceral adipose tissue), liver, muscle, and bone marrow fat content have been extensively investigated and may help to understand the underlying pathophysiological mechanisms and the multifaceted obese phenotype. MR methods have also been used to monitor changes of body fat distribution and characteristics after interventions (e.g. diet or physical activity) and revealed distinct, adipose tissue-specific properties. Lastly, chemical shift-encoding based water-fat MRI can detect brown adipose tissue which is currently the focus of intense research as a potential treatment target for obesity. In conclusion, MR methods reliably allow the assessment of body fat distribution and characteristics. Irrespective of the promising findings based on these MR methods the clinical usefulness remains to be established.

Ectopic Fat Deposition on Insulin Sensitivity: Correlation of Hepatocellular Lipid Content and M Value

Purpose. This study aimed to explore the relationship among insulin sensitivity and ectopic fat depots in participants with different glucose status. Methods. Fifty-nine men and women were enrolled in this study: 29 with normal glucose tolerance (NGT), 17 with impaired glucose tolerance (IGT), and 13 with type 2 diabetes mellitus (T2DM). All participants underwent a hyperinsulinemic-euglycemic clamp to assess the insulin sensitivity index (M value) and magnetic resonance imaging to measure the hepatocellular lipid content (HCL), skeletal muscle fat content including intramyocellular lipid (IMCL) and extramyocellular lipid (EMCL) of tibialis anterior (ta), and soleus muscle (sol). Results. The M value of NGT group was higher than those of IGT and T2DM groups (P = 0.001). Participants with T2DM had the highest HCL and IMCL (ta) compared with those in NGT and IGT groups (P = 0.001). The M value had an inverse relationship with HCL (r = -0.789, P = 0.001), IMCL (sol) (r = -0.427, P = 0.002), and IMCL (ta) (r = -0.419, P = 0.002). Stepwise linear regression analysis showed that HCL (standardized β = -0.416; P = 0.001) had an independent relationship with M value. Conclusions. Hepatocellular lipid content deposition happens earlier than skeletal muscle fat deposition. HCL is an independent risk factor for insulin resistance and may be used to evaluate the risk of developing T2DM as a noninvasive marker of insulin sensitivity index.