The magnetic resonance imaging–estimated proton density fat fraction (MRI-PDFF) is a novel imaging-based biomarker that allows fat mapping of the entire liver, whereas the magnetic resonance spectroscopy–measured proton density fat fraction (MRS-PDFF) provides a biochemical measure of liver fat in small regions of interest. Cross-sectional studies have shown that MRI-PDFF correlates with MRS-PDFF. The aim of this study was to show the utility of MRI-PDFF in assessing quantitative changes in liver fat through a three-way comparison of MRI-PDFF and MRS-PDFF with the liver histology–determined steatosis grade at two time points in patients with nonalcoholic fatty liver disease (NAFLD). Fifty patients with biopsy-proven NAFLD who participated in a randomized trial underwent a paired evaluation with liver biopsy, MRI-PDFF, and MRS-PDFF at the baseline and 24 weeks. The mean age and body mass index were 47.8 ± 11.7 years and 30.7 ± 6.5 kg/m2, respectively. MRI-PDFF showed a robust correlation with MRS-PDFF both at week 0 and at week 24 (r = 0.98, P < 0.0001 for both). Cross-sectionally, MRI-PDFF and MRS-PDFF increased with increases in the histology-determined steatosis grade both at week 0 and at week 24 (P < 0.05 for all). Longitudinally, patients who had a decrease (≥1%) or increase (≥1%) in MRI-PDFF (confirmed by MRS-PDFF) showed a parallel decrease or increase in their body weight and serum alanine aminotransferase and aspartate aminotransferase levels at week 24 (P < 0.05). This small increase or decrease in liver fat could not be quantified with histology. Conclusion In this longitudinal study, MRI-PDFF correlated well with MRS-PDFF and was more sensitive than the histology-determined steatosis grade in quantifying increases or decreases in the liver fat content. Therefore, it could be used to quantify changes in liver fat in future clinical trials.

SUMMARY Background Conventional magnetic resonance imaging (MRI) techniques that measure hepatic steatosis are limited by T1 bias, T2* decay and multi-frequency signal-interference effects of protons in fat. Newer MR techniques such as the proton density-fat fraction (PDFF) that correct for these factors have not been specifically compared to liver biopsy in adult patients with non-alcoholic fatty liver disease (NAFLD). Aim To examine the association between MRI-determined PDFF and histology-determined steatosis grade, and their association with fibrosis. Methods A total of 51 adult patients with biopsy-confirmed NAFLD underwent meta-bolic-biochemical profiling, MRI-determined PDFF measurement of hepatic steatosis and liver biopsy assessment according to NASH-CRN histological scoring system. Results The average MRI-determined PDFF increased significantly with increasing histology-determined steatosis grade: 8.9% at grade-1, 16.3% at grade-2, and 25.0% at grade-3 with P ≤ 0.0001 (correlation: r2 = 0.56, P < 0.0001). Patients with stage-4 fibrosis, when compared with patients with stage 0–3 fibrosis, had significantly lower hepatic steatosis by both MRI-determined PDFF (7.6% vs. 17.8%, P < 0.005) and histology-determined steatosis grade (1.4 vs. 2.2, P < 0.05). NAFLD patients with grade 1 steatosis were more likely to have characteristics of advanced liver disease including higher average AST:ALT (0.87 vs. 0.60, P < 0.02), GGT (140 vs. 67, P < 0.01), and INR (1.06 vs. 0.99, P < 0.01), higher stage of fibrosis and hepatocellular ballooning. Conclusions MRI-determined proton density-fat fraction correlates with histology-determined steatosis grade in adults with NAFLD. Steatosis is non-linearly related to fibrosis progression. In patients with NAFLD, a low amount of hepatic steatosis on imaging does not necessarily indicate mild disease.

Bile acid sequestrants (BAS) lower plasma low density lipoprotein levels and improve glycemic control. Colestimide, a BAS, has been claimed to reduce liver fat by computed tomography. Therefore, we examined the efficacy of colesevelam, a potent BAS, to decrease liver fat in patients with biopsy-proven nonalcoholic steatohepatitis (NASH). Liver fat was measured by a novel magnetic-resonance-imaging (MRI)-technique, the proton-density-fat-fraction (PDFF), as well as by conventional MR spectroscopy (MRS). Methods Fifty patients with biopsy-proven NASH were randomly assigned to either colesevelam 3.75 gram/day orally or placebo for 24 weeks. The primary outcome was change in liver fat as measured by MRI PDFF in co-localized regions of interest within each of the nine liver segments. Results Compared with placebo, colesevelam increased liver fat by MRI PDFF in all nine segments of the liver with a mean difference of 5.6% (p=0.002). We cross-validated the MRI-PDFF determined fat content with that assessed by co-localized MRS; the latter showed a mean difference of 4.9% (p=0.014) in liver fat between the colesevelam and the placebo-arms. MRI PDFF correlated strongly with MRS determined hepatic fat content (r2=0.96, P<0.0001). Liver biopsy assessment of steatosis, cellular injury and lobular inflammation did not detect any effect of treatment. Conclusion Colesevelam increases liver fat in patients with NASH as assessed by MRI as well as MRS without significant changes seen on histology. Thus, MRI and MRS may be better than histology to detect longitudinal changes in hepatic fat in NASH. Underlying mechanisms and whether the small MR detected increase in liver fat has clinical consequences is not known.

BackgroundInterleukin-6 (IL-6) may have a protective role in acute liver disease but a detrimental effect in chronic liver disease. It is unknown whether IL-6 is associated with risk of liver-related mortality in humans.AimsTo determine if IL-6 is associated with an increased risk of all-cause, cardiovascular disease (CVD), cancer, and liver-related mortality.MethodsA prospective cohort study included 1843 participants who attended a research visit in 1984–87. Multiple covariates were ascertained including serum IL-6. Multivariable-adjusted Cox proportional hazards regression analyses were used to examine the association between serum IL-6 as a continuous (log transformed) variable with all-cause, CVD, cancer, and liver-related mortality. Patients with prevalent CVD, cancer and liver disease were excluded for cause-specific mortality.ResultsThe mean (± standard deviation) age and body-mass-index (BMI) of participants was 68 (±10.6) years and 25 (±3.7) Kg/m2, respectively. During the 25,802 person-years of follow-up, the cumulative all-cause, CVD, cancer, and liver-related mortality were 53.1% (N = 978), 25.5%, 11.3%, and 1.3%, respectively. The median (±IQR) length of follow-up was 15.3±10.6 years. In multivariable analyses, adjusted for age, sex, alcohol, BMI, diabetes, hypertension, total cholesterol, HDL, and smoking, one-SD increment in log-transformed serum IL-6 was associated with increased risk of all-cause, CVD, cancer, and liver-related mortality, with hazard ratios of 1.48 (95% CI, 1.33–1.64), 1.38 (95% CI, 1.16–1.65), 1.35 (95% CI, 1.02–1.79), and 1.88 (95% CI, 0.97–3.67), respectively. CRP adjustment attenuated the effects but the association between IL-6 and all-cause and CVD mortality remained statistically significant, independent of CRP levels.ConclusionsIn community-dwelling older adults, serum IL-6 is associated with all-cause, CVD, cancer, and liver-related mortality.

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of abnormal liver enzymes and chronic liver disease in the US with expected rise in incidence paralleling the epidemic of obesity. A subset of patients with NAFLD have the progressive form of NAFLD that is termed non-alcoholic steatohepatitis (NASH), which is characterized by specific features on liver histology including hepatocellular ballooning degeneration, lobular inflammation, and zone-3 steatosis with or without peri-sinusoidal fibrosis. Non-alcoholic steatohepatitis can progress to cirrhosis and result in liver-related death. Insulin resistance is commonly seen in patients with NASH and often co-exists with other features of the metabolic syndrome including hypertension, hyperlipidemia, and obesity. Although weight loss through lifestyle modifications including dietary changes and increased physical exercise remains the backbone of management of NASH, it has proved challenging for patients to achieve and maintain weight loss goals. Thus, it is often necessary to couple lifestyle changes with another pharmacologic treatment for NASH. Insulin sensitizers including the biguanides (metformin), thiazolidinediones (pioglitazone and rosiglitazone), and glucagon-like peptide-1 receptor agonists (exenatide) are large groups of medications that have been studied for the treatment of NASH. Other agents with anti-inflammatory, anti-apoptotic, or anti-fibrotic properties which have been studied in NASH include vitamin E, pentoxifylline, betaine, and ursodeoxycholic acid. This review will provide a detailed summary on the clinical data behind the full spectrum of treatments that exist for NASH and suggest management recommendations. (J CLIN EXP HEPATOL 2012;2:156-173)