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The Role of Three-Dimensional Magnetic Resonance Elastography in the Diagnosis of Nonalcoholic Steatohepatitis in Obese Patients Undergoing Bariatric Surgery.

ABSTRACT: The lack of reliable, noninvasive methods to diagnose early nonalcoholic steatohepatitis (NASH) is a major unmet need. We aimed to determine the diagnostic accuracy of three-dimensional magnetic resonance elastography (3D-MRE), with shear stiffness measured at 60 Hz, damping ratio at 40 Hz, and magnetic resonance imaging proton density fat fraction (MRI-PDFF) in the detection of NASH in individuals undergoing bariatric surgery. Obese adults at risk for NASH were enrolled between 2015 and 2017 (prospective cohort, n = 88) and 2010 and 2013 (retrospective cohort, n = 87). The imaging protocol consisted of multifrequency 3D-MRE (mf3D-MRE) with shear waves delivered at different frequencies to explore parameters that best correlated with histologic NASH, and MRI-PDFF to estimate steatosis. The prospective cohort was used to establish the optimal mf3D-MRE technical parameters for NASH detection. The two cohorts were then combined to derive predictive models of NASH and disease activity by nonalcoholic fatty liver disease activity score (NAS) using the three imaging parameters that correlated with NASH. A total of 175 patients (median age 45, 81% women, and 81 [46%] with histologic NASH) were used for model derivation. From the complex shear modulus output generated by mf3D-MRE, the damping ratio at 40 Hz and shear stiffness at 60 Hz best correlated with NASH. The fat fraction obtained from MRI-PDFF correlated with steatosis (P < 0.05 for all). These three parameters were fit into a logistic regression model that predicted NASH with cross-validated area under the receiver operating characteristic curve (AUROC) = 0.73, sensitivity = 0.67, specificity = 0.80, positive predictive value = 0.73 and negative predictive value = 0.74, and disease activity by NAS with cross-validated AUROC = 0.82. Conclusion: The mf3D-MRE allows identification of imaging parameters that predict early NASH and disease activity. This imaging biomarker represents a promising alternative to liver biopsy for NASH diagnosis and monitoring. The results provide motivation for further studies in nonbariatric cohorts.

SUBMITTER: Allen AM

PROVIDER: S-EPMC6591099 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Project description:Background & aimsBariatric surgery is associated with improved outcomes in subjects with severe obesity. We investigated the prognostic relevance of nonalcoholic steatohepatitis (NASH) and liver gene expression patterns in patients undergoing bariatric surgery.MethodsWe performed a retrospective analysis of 492 subjects who underwent gastric bypass bariatric surgery at a single center in Switzerland from January 1997 through December 2004; routine perioperative liver biopsies were collected, analyzed histologically, and RNA was isolated. We collected data on overall survival and clinical and biochemical parameters and compared these with data from propensity score-matched subjects participating in the third National Health and Nutrition Examination Survey (NHANES III). We used liver biopsies to identify bariatric surgery patients with NASH; NHANES III participants with NASH were identified based on a hyperechogenic liver at ultrasound and increased alanine transaminase levels. We analyzed a 32-gene signature associated with NAFLD severity in the liver tissues collected from 47 bariatric surgery patients with NASH, and assessed its prognostic features using nearest template prediction and survival analysis.ResultsAt baseline, the median body mass index of patients who underwent bariatric surgery was 43.6 kg/m2; based on histologic findings, 12% had NASH and 16% had fibrosis. During a median follow-up of 10.2 years after the surgery, 4.2% of the subjects died. In multivariable Cox regression, the presence of NASH (hazard ratio [HR], 2.9; P = .02) and arterial hypertension (HR, 3.9; P = .02) were associated with overall mortality. When bariatric surgery patients were matched with NHANES III participants, bariatric surgery reduced the risk of death during the follow-up period (HR, 0.54; P = .04). However, bariatric surgery patients with NASH did not have a reduced risk of death compared with NHANES III participants with NASH (HR, 0.90; P = .85). We identified an expression pattern of 32 genes in liver tissues from patients with NASH that was associated with increased risk of death in multivariable analysis (HR, 7.7; P = .045).ConclusionsHistologically proven NASH is associated with increased risk of death within a median follow-up of 10.2 years after bariatric surgery, compared with patients who undergo bariatric surgery without NASH. The survival benefit of bariatric surgery in subjects with NASH may be reduced. A 32-gene expression pattern identified patients with NASH who underwent bariatric surgery and had shorter survival times.

Project description:UNLABELLED:Ezetimibe inhibits intestinal cholesterol absorption and lowers low-density lipoprotein cholesterol. Uncontrolled studies have suggested that it reduces liver fat as estimated by ultrasound in nonalcoholic steatohepatitis (NASH). Therefore, we aimed to examine the efficacy of ezetimibe versus placebo in reducing liver fat by the magnetic resonance imaging-derived proton density-fat fraction (MRI-PDFF) and liver histology in patients with biopsy-proven NASH. In this randomized, double-blind, placebo-controlled trial, 50 patients with biopsy-proven NASH were randomized to either ezetimibe 10 mg orally daily or placebo for 24 weeks. The primary outcome was a change in liver fat as measured by MRI-PDFF in colocalized regions of interest within each of the nine liver segments. Novel assessment by two-dimensional and three-dimensional magnetic resonance elastography was also performed. Ezetimibe was not significantly better than placebo at reducing liver fat as measured by MRI-PDFF (mean difference between the ezetimibe and placebo arms -1.3%, P = 0.4). Compared to baseline, however, end-of-treatment MRI-PDFF was significantly lower in the ezetimibe arm (15%-11.6%, P < 0.016) but not in the placebo arm (18.5%-16.4%, P = 0.15). There were no significant differences in histologic response rates, serum alanine aminotransferase and aspartate aminotransferase levels, or longitudinal changes in two-dimensional and three-dimensional magnetic resonance elastography-derived liver stiffness between the ezetimibe and placebo arms. Compared to histologic nonresponders (25/35), histologic responders (10/35) had a significantly greater reduction in MRI-PDFF (-4.35 ± 4.9% versus -0.30 ± 4.1%, P < 0.019). CONCLUSIONS:Ezetimibe did not significantly reduce liver fat in NASH. This trial demonstrates the application of colocalization of MRI-PDFF-derived fat maps and magnetic resonance elastography-derived stiffness maps of the liver before and after treatment to noninvasively assess treatment response in NASH.

Project description:BackgroundNonalcoholic steatohepatitis (NASH) is the advanced stage of nonalcoholic fatty liver disease (NAFLD), one of the most prevalent chronic liver diseases. The effectiveness of bariatric surgery in treating NASH and preventing or even reversing liver fibrosis has been demonstrated in numerous clinical studies, but the underlying mechanisms and crucial variables remain unknown.MethodsUsing the GSE135251 dataset, we examined the gene expression levels of NASH and healthy livers. Then, the differentially expressed genes (DEGs) of patients with NASH, at baseline and one year after bariatric surgery, were identified in GSE83452. We overlapped the hub genes performed by protein-protein interaction (PPI) networks and DEGs with different expression trends in both datasets to obtain key genes. Genomic enrichment analysis (GSEA) and genomic variation analysis (GSVA) were performed to search for signaling pathways of key genes. Meanwhile, key molecules that regulate the key genes are found through the construction of the ceRNA network. NASH mice were induced by a high-fat diet (HFD) and underwent sleeve gastrectomy (SG). We then cross-linked the DEGs in clinical and animal samples using quantitative polymerase chain reaction (qPCR) and validated the key genes.ResultsSeven key genes (FASN, SCD, CD68, HMGCS1, SQLE, CXCL10, IGF1) with different expression trends in GSE135251 and GSE83452 were obtained with the top 30 hub genes selected by PPI. The expression of seven key genes in mice after SG was validated by qPCR. Combined with the qPCR results from NASH mice, the four genes FASN, SCD, HMGCS1, and CXCL10 are consistent with the biological analysis. The GSEA results showed that the 'cholesterol homeostasis' pathway was enriched in the FASN, SCD, HMGCS1, and SQLE high-expression groups. The high-expression groups of CD68 and CXCL10 were extremely enriched in inflammation-related pathways. The construction of the ceRNA network obtained microRNAs and ceRNAs that can regulate seven key genes expression.ConclusionIn summary, this study contributes to our understanding of the mechanisms by which bariatric surgery improves NASH, and to the development of potential biomarkers for the treatment of NASH.

Project description:BackgroundTreatments for nonalcoholic steatohepatitis (NASH) are urgently needed. Hepatic fat fraction and shear stiffness quantified by magnetic resonance imaging (MRI-HFF) and magnetic resonance elastography (MRE-SS), respectively, are biomarkers for hepatic steatosis and fibrosis.PurposeThis study assessed the longitudinal effects of fibroblast growth factor 21 variant (polyethylene glycol [PEG]-FGF21v) on MRI-HFF and MRE-SS in a NASH mouse model.Study typePreclinical.Animal modelThis study included a choline-deficient, amino acid-defined, high-fat diet (CDAHFD) model and 6-week-old, male C57BL/6J mice (N = 78).Field strength/sequenceThis study was performed using: 3T: gradient-echo two-point Dixon and spin-echo (SE) echo-planar imaging elastography (200 Hz) and 7T: SE two-point Dixon and SE elastography (200 Hz).AssessmentMRI and MRE were performed before control diet (CD) or CDAHFD (BD), before PEG-FGF21v dosing (baseline), and after PEG-FGF21v treatment (WK4/8). Regions of interest for MRI-HFF and MRE-SS were delineated by J.L. and H.T. (>5 years of experience each). Fibrosis and steatosis were measured histologically after picrosirius red and H&E staining. Alkaline phosphatase, alanine transaminase, bile acids, and triglycerides (TGs) were measured.Statistical testsTwo-tailed Dunnett's tests were used for statistical analysis; untreated CDAHFD or baseline was used for comparisons. Imaging and histology/biochemistry data were determined using Spearman correlations. Bayesian posterior distributions for MRE-SS at WK8, posterior means, and 95% credible intervals were presented.ResultsCDAHFD significantly increased baseline MRI-HFF (3T: 21.97% ± 0.29%; 7T: 40.12% ± 0.35%) and MRE-SS (3T: 1.25 ± 0.02; 7T: 1.78 ± 0.06 kPa) vs. CD (3T: 3.45% ± 0.7%; 7T: 12.06% ± 1.4% and 3T: 1.01 ± 0.02; 7T: 0.89 ± 0.06 kPa). At 7T, PEG-FGF21v significantly decreased MRI-HFF (WK4: 28.97% ± 1.22%; WK8: 20.93% ± 1.15%) and MRE-SS (WK4: 1.57 ± 0.04; WK8: 1.36 ± 0.05 kPa) vs. untreated (WK4: 36.36% ± 0.62%; WK8: 30.58% ± 0.81% and WK4: 2.03 ± 0.06; WK8: 2.01 ± 0.04 kPa); 3T trends were similar. WK8 SS posterior mean percent attenuation ratios (RDI ) were -68% (-90%, -44%; 3T) and -64% (-78%, -52%; 7T). MRI-HFF was significantly correlated with H&E (3T, r = 0.93; 7T, r = 0.94) and TGs (both, r = 0.92).Data conclusionsMRI-HFF and MRE-SS showed PEG-FGF21v effects on hepatic steatosis and fibrosis across 3 and 7T, consistent with histological and biochemical data.Level of evidence1 TECHNICAL EFFICACY STAGE: 2.

Project description:ImportanceObesity is the most common risk factor for nonalcoholic steatohepatitis (NASH), the progressive form of nonalcoholic fatty liver disease that can lead to cirrhosis and hepatocellular carcinoma. Weight loss can be an effective treatment for obesity and may slow the progression of advanced liver disease.ObjectiveTo assess the cost-effectiveness of bariatric surgery in patients with NASH and compensated cirrhosis.Design, setting, and participantsThis economic evaluation study used a Markov-based state-transition model to simulate the benefits and risks of laparoscopic sleeve gastrectomy (SG), laparoscopic Roux-en-Y gastric bypass (GB), and intensive lifestyle intervention (ILI) compared with usual care in patients with NASH and compensated cirrhosis and varying baseline weight (overweight, mild obesity, moderate obesity, and severe obesity). Patients faced varied risks of perioperative mortality and complications depending on the type of surgery they underwent. Data were collected on March 22, 2017.Main outcomes and measuresLife-years, quality-adjusted life-years (QALYs), costs (in 2017 $US), and incremental cost-effectiveness ratios (ICERs) were calculated.ResultsDemographic characteristics of the patient population were based on a previously published prospective study (n = 161). Patients in the model were 41.0% female, and the base case age was 54 years. Compared with usual care, SG was associated with an increase in QALYs of 0.263 to 1.180 (bounds of ranges represent overweight to severe obesity); GB, 0.263 to 1.207; and ILI, 0.004 to 0.216. Sleeve gastrectomy was also associated with an increase in life-years of 0.693 to 1.930; GB, 0.694 to 1.947; and ILI, 0.012 to 0.114. With usual care, expected life-years in overweight, mild obesity, moderate obesity, and severe obesity were 12.939, 11.949, 10.976, and 10.095, respectively. With usual care, QALY in overweight was 6.418; mild obesity, 5.790; moderate obesity, 5.186; and severe obesity, 4.577. Sleeve gastrectomy was the most cost-effective option for patients across all weight classes assessed: ICER for SG in patients with overweight was $66 119 per QALY; mild obesity, $18 716 per QALY; moderate obesity, $10 274 per QALY; and severe obesity, $6563 per QALY. A threshold analysis on the procedure cost of GB found that for GB to be cost-effective, the cost of the surgery must be decreased from its baseline value of $28 734 by $4889 for mild obesity, by $3189 for moderate obesity, and by $2289 for severe obesity. In overweight patients, GB involved fewer QALYs than SG, and thus decreasing the cost of surgery would not result in cost-effectiveness.Conclusions and relevanceBariatric surgery could be highly cost-effective in patients with NASH compensated cirrhosis and obesity or overweight. The findings from this analysis suggest that it can inform clinical trials evaluating the effect of bariatric procedures in patients with NASH cirrhosis, including those with a lower body mass index.

Project description:Background & aimsLittle is known about the prevalence of nonalcoholic fatty liver disease (NAFLD) among severely obese adolescents or factors that determine its development. We investigated the prevalence of NAFLD in a multicenter cohort of adolescents undergoing bariatric surgery and the factors associated with it.MethodsWe enrolled 242 adolescents undergoing bariatric surgery between March 2007 and February 2012 at 5 tertiary care centers into a multicenter, prospective observational cohort study. Intraoperative core liver biopsies were collected from 165 subjects; 17 were excluded because of insufficient liver tissue or use of hepatotoxic medications, so 148 remained in the study (mean age, 16.8 ± 1.6 years; median body mass index = 52 kg/m(2)). Liver tissues were analyzed by histology using validated criteria. Hepatic gene expression was analyzed in 67 samples.ResultsNAFLD was present in 59% of this predominantly female (72%), white (68%), non-Hispanic (91%) cohort. Of subjects with NAFLD, 24% had borderline and 10% had definite nonalcoholic steatohepatitis (NASH). Mild fibrosis (stage 2 or lower) was observed in 18% of liver biopsies and stage 3 was observed in 0.7%, but cirrhosis was not detected. Dyslipidemia was present in 78% of subjects, hypertension in 44%, and diabetes in 14%. More severe NAFLD was associated with increasing levels of alanine aminotransferase, fasting glucose level, hypertension (each P < .01), and white blood cell count (P = .04). Only diabetes was associated with detection of fibrosis (odds ratio = 3.56; 95% confidence interval: 1.93-6.56). Microarray analysis associated presence of NASH with altered expression of genes that regulate macrophage chemotaxis, cholesterol absorption, and fatty acid binding.ConclusionsMore than half of adolescents undergoing bariatric surgery in this cohort had NAFLD, yet the prevalence of severe or fibrotic NASH was low. Increasing severity of NAFLD was associated with level of alanine aminotransferase and cardiometabolic risk factors, but not body mass index. Based on gene expression analysis, borderline and definite NASH were associated with abnormal immune function, intestinal cholesterol absorption, and lipid metabolism.

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The Role of Three-Dimensional Magnetic Resonance Elastography in the Diagnosis of Nonalcoholic Steatohepatitis in Obese Patients Undergoing Bariatric Surgery.

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