Hepatic lipid profiling in chronic hepatitis C: an in vitro and in vivo proton magnetic resonance spectroscopy study

Near infrared spectroscopy (NIRS) and machine learning as a promising tandem for fast viral detection in serum microsamples: A preclinical proof of concept

Fast detection of viral infections is a key factor in the strategy for the prevention of epidemics expansion and follow-up. Hepatitis C is paradigmatic within viral infectious diseases and major challenges to elimination still remain. Near infrared spectroscopy (NIRS) is an inexpensive, clean, safe method for quickly detecting viral infection in transmission vectors, aiding epidemic prevention. Our objective is to evaluate the combined potential of machine learning and NIRS global molecular fingerprint (GMF) from biobank sera as an efficient method for HCV activity discrimination in serum. GMF of 151 serum biobank microsamples from hepatitis C patients were obtained with a FT-NIR spectrophotometer in reflectance mode. Multiple scatter correction, smoothing and Saviztsky-Golay second derivative were applied. Spectral analysis included Principal Component Analysis (PCA), Bootstrap and L1-penalized classification. Microsamples of 70 µl were sufficient for GMF acquisition. Bootstrap evidenced significant difference between HCV PCR positive and negative sera. PCA renders a neat discrimination between HCV PCR-positive and negative samples. PCA loadings together with L1-penalized classification allow the identification of discriminative bands. Active virus positive sera are associated to free molecular water, whereas water in solvation shells is associated to HCV negative samples. Divergences in the water matrix structure and the lipidome between HCV negative and positive sera, as well as the relevance of prooxidants and glucose metabolism are reported as potential biomarkers of viral activity. Our proof of concept demonstrates that NIRS GMF of hepatitis C patients' sera aided by machine learning allows for efficient discrimination of viral presence and simultaneous potential biomarker identification.

Role of Advanced MRI Techniques in the Quantitative Assessment of Liver Fat—A Multimodality-Based Comparative Study of Diagnostic Performance in a Tertiary Care Institute

Objective To evaluate the accuracy of noninvasive imaging methods including gray-scale ultrasound, ultrasound shear wave elastography, unenhanced computed tomography (CT), and proton density fat fraction (PDFF) on magnetic resonance imaging (MRI) using three-dimensional (3D) multiecho multipoint chemical shift–encoded spoiled gradient echo (q-DIXON) sequence in the quantification of hepatic steatosis, with proton MR spectroscopy (H1-MRS) as the reference standard in Indian population.

Methods Our study included 100 consecutive adult patients referred to the department of radiology in our hospital for imaging of liver. Fat content of liver was recorded using MRI (H1-MRS and q-DIXON), unenhanced CT (average liver attenuation [ALI] and liver attenuation index [LAI]) and ultrasonography (USG) (gray-scale grading and shear wave elastography [SWE]). Data were analyzed by linear regression and Bland–Altman analysis for each technique compared with H1-MRS. The diagnostic performances of all the methods were compared using DeLong test, for detection of mild and moderate-to-severe hepatic steatosis, separately.

Results MRI q-DIXON PDFF showed excellent correlation (r = 0.917, r2 = 0.840) and strong agreement (1.48 ±3.01) with H1-MRS-derived PDFF measurements. Unenhanced CT-based methods showed moderate correlation with modest agreement (r = −0.826, r2 = 0.681, −40.18 ± 16.05 for ALI and r = −0.858, r2 = 0.735, 13.4 ± 15.3 for LAI) whereas USG gray-scale assessment showed low correlation (weighted Kappa value 0.366) with H1-MRS PDFF. No correlation was found between USG-SWE results and PDFF measured with H1-MRS. Comparison of areas under curve (AUCs) using DeLong test revealed that MRI q-DIXON method performed the best for diagnosis of hepatic steatosis compared with rest. For moderate to severe steatosis, MRI q-DIXON and unenhanced CT-based methods had comparable diagnostic performance with AUCs not showing statistically significant differences.

Conclusion MRI q-DIXON shows strongest correlation with MRS and should be preferred for estimation of hepatic fat, especially when MRS is not available. Unenhanced CT shows limited diagnostic performance in detecting mild steatosis; however, it certainly has a role in diagnosing moderate-to-severe hepatic steatosis, such as evaluating donor candidates for living donor liver transplantation. USG, using both the traditional four-grade visual assessment and elastography in the present form, appears to have limited role in liver fat quantification.

1H NMR-Based Metabolic Signatures in the Liver and Brain in a Rat Model of Hepatic Encephalopathy

Hepatic encephalopathy (HE) is a debilitating neuropsychiatric complication associated with acute and chronic liver failure. It is characterized by diverse symptoms with variable severity that includes cognitive and motor deficits. The aim of the study is to assess metabolic alterations in the brain and liver using nuclear magnetic resonance (NMR) spectroscopy and subsequent multivariate analyses to characterize metabolic signatures associated with HE. HE was developed by bile duct ligation (BDL) that resulted in hepatic dysfunctions and cirrhosis as shown by liver function tests. Metabolic profiles from control and BDL rats indicated increased levels of lactate, branched-chain amino acids (BCAAs), glutamate, and choline in the liver, whereas levels of glucose, phenylalanine, and pyridoxine were decreased. In brain, the levels of lactate, acetate, succinate, citrate, and malate were increased, while glucose, creatine, isoleucine, leucine, and proline levels were decreased. Furthermore, neurotransmitters such as glutamate and GABA were increased, whereas choline and myo-inositol were decreased. The alterations in neurotransmitter levels resulted in cognitive and motor defects in BDL rats. A significant correlation was found among alterations in NAA/choline, choline/creatine, and NAA/creatine with behavioral deficits. Thus, the data suggests impairment in metabolic pathways such as the tricarboxylic acid (TCA) cycle, glycolysis, and ketogenesis in the liver and brain of animals with HE. The study highlights that metabolic signatures could be potential markers to monitor HE progression and to assess therapeutic interventions.

Improved quantitative fatty acid values with correction of T2 relaxation time in terminal methyl group: In vivo proton magnetic resonance spectroscopy at ultra high field in hepatic steatosis

Proton magnetic resonance spectroscopy (MRS) with optimized relaxation time is an effective method to quantify hepatic fatty acid values and characterize steatosis. The aim of this study is to quantify the difference in hepatic lipid content with metabolic changes during the progression of steatosis by using localized MRS sequence with T₂ relaxation time determination. Fatty liver disease was induced in C57BL/6N mice through a high-fat diet (HFD) of pellets containing 60% fat, 20% protein, and 20% carbohydrates. We used stimulated echo acquisition mode (repetition time: 3500 ms; mixing time: 10 ms; echo time: 20 ms) sequence. Using enhanced and mono exponential curve-fitting methods, the lipid relaxation time in mice was estimated at a fixed repetition time of 5000 ms and echo time ranging from 20 to 70 ms. The calculated lipid contents with incorrect and correct relaxation times were as follows: total saturated fatty acid (4.00 ± 2.90 vs 6.74 ± 2.25, p < 0.05 at week 0; 15.23 ± 9.94 vs 25.53 ± 10.49, p < 0.05 at week 4); total unsaturated fatty acid (0.40 ± 0.49 vs 0.56 ± 0.47, p < 0.05 at week 4; 0.33 ± 0.26 vs 0.60 ± 0.21, p < 0.01 at week 7); total unsaturated bond (0.48 ± 0.52 vs 1.05 ± 0.58, p < 0.05 at week 10). Furthermore, we determined that the correct relaxation times of triglycerides between 0 and 10 weeks were significantly altered in the resonances (∼2.03 ppm: 31.07 ± 1.00 vs 27.62 ± 1.20, p < 0.01; ∼2.25 ppm: 29.10 ± 1.52 vs 26.39 ± 1.08, p < 0.05; ∼2.78 ppm: 37.67 ± 2.92 vs 29.37 ± 2.64, p < 0.001). The work presented focused on the significance of the J-coupling effect. The selection of an appropriate relaxation time considering the J-coupling effect provides an effective method for quantifying lipid contents and characterizing hepatic steatosis.

Nuclear magnetic resonance metabolomics and human liver diseases: The principles and evidence associated with protein and carbohydrate metabolism

During the last decade, metabolomics has become widely used in the field of human diseases. Numerous studies have demonstrated that this is a powerful technique for improving the understanding, diagnosis and management of various types of liver disease, such as acute and chronic liver diseases, and liver transplantation. Nuclear magnetic resonance (NMR) spectroscopy is one of the two most commonly applied methods for metabolomics. The aim of the present review was to investigate the results from recent key publications focusing on aspects of protein and carbohydrate metabolism. The review includes existing procedures, which are currently used for NMR data acquisition and statistical analysis. In addition, notable results obtained by these studies on protein and carbohydrate metabolism concerning human liver diseases are presented.

Longitudinal metabolic imaging of hepatocellular carcinoma in transgenic mouse models identifies acylcarnitine as a potential biomarker for early detection

The cumulative effects of hepatic injury due to hepatitis B virus (HBV) infections and aflatoxin-B₁ (AFB₁) exposure are the major risk factors of HCC. Understanding early metabolic changes involving these risk factors in an animal model closely resembling human hepatocellular carcinoma (HCC) is critical for biomarker discovery and disease therapeutics. We have used the hepatitis B surface antigen (HBsAg) transgenic mouse model that mimics HBV carriers with and without AFB1 treatment. We investigated early metabolic changes from preneoplastic state to HCC by non-invasive longitudinal imaging in three HCC groups of mice: HBsAg + AFB₁(Gp-I), AFB₁ alone (Gp-II), HBsAg alone (Gp-III) and a control group (wild-type untreated; Gp-IV). For the first time, we have identified acylcarnitine signals in vivo in the liver prior to the histological manifestation of the tumors in all three groups. Acylcarnitine concentration increased with increase in tumor growth in all HCC mouse models, indicating elevated metabolic activity and increased cell turnover. This was confirmed in a pilot study using human serum from HCC patients, which revealed a higher concentration of acylcarnitine compared with normal subjects. Translational clinical studies can be designed to detect acylcarnitine in patients with high risk factors for HCC.

Characterization of hepatic fatty acids in mice with reduced liver fat by ultra-short echo time (1)H-MRS at 14.1 T in vivo

Alterations in the hepatic lipid content (HLC) and fatty acid composition are associated with disruptions in whole body metabolism, both in humans and in rodent models, and can be non-invasively assessed by (1)H-MRS in vivo. We used (1)H-MRS to characterize the hepatic fatty-acyl chains of healthy mice and to follow changes caused by streptozotocin (STZ) injection. Using STEAM at 14.1 T with an ultra-short TE of 2.8 ms, confounding effects from T2 relaxation and J-coupling were avoided, allowing for accurate estimations of the contribution of unsaturated (UFA), saturated (SFA), mono-unsaturated (MUFA) and poly-unsaturated (PUFA) fatty-acyl chains, number of double bonds, PU bonds and mean chain length. Compared with in vivo (1) H-MRS, high resolution NMR performed in vitro in hepatic lipid extracts reported longer fatty-acyl chains (18 versus 15 carbons) with a lower contribution from UFA (61 ± 1% versus 80 ± 5%) but a higher number of PU bonds per UFA (1.39 ± 0.03 versus 0.58 ± 0.08), driven by the presence of membrane species in the extracts. STZ injection caused a decrease of HLC (from 1.7 ± 0.3% to 0.7 ± 0.1%), an increase in the contribution of SFA (from 21 ± 2% to 45 ± 6%) and a reduction of the mean length (from 15 to 13 carbons) of cytosolic fatty-acyl chains. In addition, SFAs were also likely to have increased in membrane lipids of STZ-induced diabetic mice, along with a decrease of the mean chain length. These studies show the applicability of (1)H-MRS in vivo to monitor changes in the composition of the hepatic fatty-acyl chains in mice even when they exhibit reduced HLC, pointing to the value of this methodology to evaluate lipid-lowering interventions in the scope of metabolic disorders.

Gender and age groups interactions in the quantification of bone marrow fat content in lumbar spine using 3T MR spectroscopy: a multivariate analysis of covariance (Mancova)

INTRODUCTION

There is an age-related conversion of red to yellow bone marrow in the axial skeleton, with a gender-related difference less well established. Our purpose was to clarify the variability of bone marrow fat fraction (FF) in the lumbar spine due to the interaction of gender and age groups.

METHODS

44 healthy volunteers (20 males, 30-65 years old and 24 females, 30-69 years old) underwent 3T magnetic resonance spectroscopy (MRS) and conventional MRI examination of the lumbar spine; single-voxel spectrum was acquired for each vertebral body (VB). After controlling body mass index (BMI), a two-way between-groups multivariate analysis of covariance (MANCOVA) assessed the gender and age group differences in FF quantification for each lumbar VB.

RESULTS

There was a significant interaction between gender and age group, p=.017, with a large effect size (partial η(2)=.330). However the interaction explained only 33% of the observed variance. Main effects were not statistically significant. BMI was non-significantly related to FF quantification.

CONCLUSIONS

Young males showed a high FF content, which declined in the 4th decade, then increased the next 3 decades to reach a FF content just below the initial FF means. Females' FF were low in the 3rd decade, depicted an accelerated increase in the 4th decade, then a gradual increase the next 3 decades to reach a FF content similar to males' values. Our findings suggest that quantification of bone marrow FF using MRS might be used as a surrogate biomarker of bone marrow activity in clinical settings.

In vivo hepatic lipid quantification using MRS at 7 Tesla in a mouse model of glycogen storage disease type 1a

The assessment of liver lipid content and composition is needed in preclinical research to investigate steatosis and steatosis-related disorders. The purpose of this study was to quantify in vivo hepatic fatty acid content and composition using a method based on short echo time proton magnetic resonance spectroscopy (MRS) at 7 Tesla. A mouse model of glycogen storage disease type 1a with inducible liver-specific deletion of the glucose-6-phosphatase gene (L-G6pc(-/-)) mice and control mice were fed a standard diet or a high-fat/high-sucrose (HF/HS) diet for 9 months. In control mice, hepatic lipid content was found significantly higher with the HF/HS diet than with the standard diet. As expected, hepatic lipid content was already elevated in L-G6pc(-/-) mice fed a standard diet compared with control mice. L-G6pc(-/-) mice rapidly developed steatosis which was not modified by the HF/HS diet. On the standard diet, estimated amplitudes from olefinic protons were found significantly higher in L-G6pc(-/-) mice compared with that in control mice. L-G6pc(-/-) mice showed no noticeable polyunsaturation from diallylic protons. Total unsaturated fatty acid indexes measured by gas chromatography were in agreement with MRS measurements. These results showed the great potential of high magnetic field MRS to follow the diet impact and lipid alterations in mouse liver.

Identification of serum proton NMR metabolomic fingerprints associated with hepatocellular carcinoma in patients with alcoholic cirrhosis

PURPOSE

Metabolomics depicts metabolic changes in biologic systems using a multiparametric analysis technique. This study assessed the metabolomic profiles of serum, obtained by proton nuclear magnetic resonance (NMR) spectroscopy, from cirrhotic patients with and without hepatocellular carcinoma (HCC).

EXPERIMENTAL DESIGN

The study included 154 consecutive patients with compensated biopsy-proven alcoholic cirrhosis. Among these, 93 had cirrhosis without HCC, 28 had biopsy-proven HCC within the Milan criteria and were eligible for curative treatment (small HCC), and 33 had HCC outside the Milan criteria (large HCC). Proton spectra were acquired at 500 MHz. An orthogonal partial latent structure [orthogonal projection to latent structure (OPLS)] analysis model was built to discriminate large HCC spectra from cirrhotic spectra. Small HCC spectra were secondarily projected using previously built OPLS discriminant components.

RESULTS

The OPLS model showed discrimination between cirrhotic and large HCC spectra. Metabolites that significantly increased with large HCC were glutamate, acetate, and N-acetyl glycoproteins, whereas metabolites that correlated with cirrhosis were lipids and glutamine. Projection of small HCC samples into the OPLS model showed a heterogeneous distribution between large HCC and cirrhotic samples. Small HCC patients with metabolomic profile similar to those of large HCC group had higher incidences of recurrence or death during follow-up.

CONCLUSIONS

Serum NMR-based metabolomics identified metabolic fingerprints that could be specific to large HCC in cirrhotic livers. From a metabolomic standpoint, some patients with small HCC, who are eligible for curative treatments, seem to behave as patients with advanced cancerous disease. It would be useful to further prospectively investigate these patients to define a subgroup with a worse prognosis.

In vivo (1)H-MRS hepatic lipid profiling in nonalcoholic fatty liver disease: an animal study at 9.4 T

The applicability of the in vivo proton magnetic resonance spectroscopy hepatic lipid profiling (MR-HLP) technique in nonalcoholic fatty liver disease was investigated. Using magnetic resonance spectroscopy, the relative fractions of diunsaturated (fdi), monounsaturated (fmono), and saturated (fsat) fatty acids as well as total hepatic lipid content were estimated in the livers of 8 control and 23 CCl4-treated rats at 9.4 T. The mean steatosis, necrosis, inflammation, and fibrosis scores of the treated group were all significantly higher than those of the control group (P < 0.01). There was a strong correlation between the histopathologic parameters and the MR-HLP parameters (r = 0.775, P < 0.01) where both steatosis and fibrosis are positively correlated with fmono and negatively correlated with fdi. Both necrosis and inflammation, however, were not correlated with any of the MR-HLP parameters. Hepatic lipid composition appears to be changed in association with the severity of steatosis and fibrosis in nonalcoholic fatty liver disease, and these changes can be depicted in vivo by using the MR-HLP method at 9.4 T. Thus, while it may not likely be that MR-HLP helps differentiate between steatohepatitis in its early stages and simple steatosis, these findings altogether are in support of potential applicability of in vivo MR-HLP at high field in nonalcoholic fatty liver disease.

Evaluation of single and combination therapies with tenofovir disoproxil fumarate and emtricitabine in vitro and in a robust mouse model supporting high levels of hepatitis B virus replication

Next-generation therapies for chronic hepatitis B virus (HBV) infection will involve combinations of established and/or experimental drugs. The current study investigated the in vitro and in vivo efficacy of tenofovir disoproxil fumarate (TDF) and/or emtricitabine [(-)-FTC] alone and in combination therapy for HBV infection utilizing the HepAD38 system (human hepatoblastoma cells transfected with HBV). Cellular pharmacology studies demonstrated increased levels of (-)-FTC triphosphate with coincubation of increasing concentrations of TDF, while (-)-FTC had no effect on intracellular tenofovir (TFV) diphosphate levels. Quantification of extracellular HBV by real-time PCR from hepatocytes demonstrated the anti-HBV activity with TDF, (-)-FTC, and their combination. Combination of (-)-FTC with TDF or TFV (ratio, 1:1) had a weighted average combination index of 0.7 for both combination sets, indicating synergistic antiviral effects. No cytotoxic effects were observed with any regimens. Using an in vivo murine model which develops robust HBV viremia in nude mice subcutaneously injected with HepAD38 cells, TDF (33 to 300 mg/kg of body weight/day) suppressed virus replication for up to 10 days posttreatment. At 300 mg/kg/day, (-)-FTC strongly suppressed virus titers to up to 14 days posttreatment. Combination therapy (33 mg/kg/day each drug) sustained suppression of virus titer/ml serum (<1 log(10) unit from pretreatment levels) at 14 days posttreatment, while single-drug treatments yielded virus titers 1.5 to 2 log units above the initial virus titers. There was no difference in mean alanine aminotransferase values or mean wet tumor weights for any of the groups, suggesting a lack of drug toxicity. TDF-(-)-FTC combination therapy provides more effective HBV suppression than therapy with each drug alone.

Assessment of inflammation and fibrosis in non-alcoholic fatty liver disease by imaging-based techniques

Non-alcoholic fatty liver disease (NALFD) is a burgeoning global health problem, and the assessment of disease severity remains a clinical challenge. Conventional imaging and clinical blood tests are frequently unable to determine disease activity (the degree of inflammatory change) and fibrotic severity, while the applicability of histological examination of liver biopsy is limited. Imaging platforms provide liver-specific structural information, while newer applications of these technologies non-invasively exploit the physical and chemical characteristics of liver tissue in health and disease. In this review, conventional and newer imaging-based techniques for the assessment of inflammation and fibrosis in NAFLD are discussed in terms of diagnostic accuracy, radio-pathological correlations, and practical considerations. In particular, recent clinical studies of ultrasound (US)-based and magnetic resonance elastography techniques are evaluated, while the potential of contrast-enhanced US and magnetic resonance spectroscopy techniques is discussed. The development and application of these techniques is starting to reduce the clinical need for liver biopsy, to produce surrogate end-points for interventional and observational clinical studies, and through this, to provide new insights into the natural history of NAFLD.

Lipid profiling of pre-treatment liver biopsy tissue predicts sustained virological response in patients with chronic hepatitis C

AIM

  Hepatic lipid is important in the pathogenesis and progression of hepatitis C-related liver disease. Polyunsaturated fatty acids have been shown to reduce viral replication in cell culture. Proton magic angle spinning magnetic resonance spectroscopy ((1) H MAS MRS) enables metabolic analysis of intact tissue. The aim was to examine the relationship between hepatic lipid composition by metabolic profiling of liver tissue at baseline and treatment response to pegylated-Interferon alfa2 and Ribavirin.

METHODS

  Baseline liver biopsy samples from 31 patients with chronic hepatitis C were analyzed histologically and by (1) H MAS MRS. Indices of lipid composition were derived and partial least squares discriminant analysis with cross-validation was used to predict treatment outcome.

RESULTS

  Of 31 patients, 14 achieved sustained virological response (SVR). Lipid polyunsaturation (median (IQR)) was higher in SVR (3.41% (2.31)) than in treatment failure (TF) (2.15% (1.51)), P = 0.02. Lipid saturation was lower in SVR (85.9% (3.39)) than TF (86.7% (2.17)), P = 0.04. The total lipid content was lower in SVR (1.54% (0.81)) than TF (2.72% (3.47)), P = 0.004. Total choline to lipid ratio was higher in SVR (11.51% (9.99)) than TF (7.5% (6.82)), P = 0.007. Cross-validation correctly predicted the SVR group in 13 of 14 samples with 1 sample misclassified, and the TF group in all 17 samples.

CONCLUSIONS

  Lipid polyunsaturation was greater and total lipid lower in those with SVR, compared with TF. Metabolic profiling of intact liver biopsy samples predicted SVR with high accuracy. Hepatic lipid composition may impact on treatment success.

Serum metabolomics reveals the deregulation of fatty acids metabolism in hepatocellular carcinoma and chronic liver diseases

Patients with chronic liver diseases (CLD) including chronic hepatitis B and hepatic cirrhosis (CIR) are the major high-risk population of hepatocellular carcinoma (HCC). The differential diagnosis between CLD and HCC is a challenge. This work aims to study the related metabolic deregulations in HCC and CLD to promote the discovery of the differential metabolites for distinguishing the different liver diseases. Serum metabolic profiling analysis from patients with CLD and HCC was performed using a liquid chromatography-mass spectrometry system. The acquired large amount of metabolic information was processed with the random forest-recursive feature elimination method to discover important metabolic changes. It was found that long-chain acylcarnitines accumulated, whereas free carnitine, medium and short-chain acylcarnitines decreased with the severity of the non-malignant liver diseases, accompanied with corresponding alterations of enzyme activities. However, the general changing extent was smaller in HCC than in CIR, possibly due to the special energy-consumption mechanism of tumor cells. These observations may help to understand the mechanism of HCC occurrence and progression on the metabolic level and provide information for the identification of early and differential metabolic markers for HCC.

Effect of disease progression on liver apparent diffusion coefficient values in a murine model of NASH at 11.7 Tesla MRI

PURPOSE

To evaluate the apparent diffusion coefficient (ADC) values of liver in a murine model of non-alcoholic steatohepatitis using 11.7 Tesla (T) MRI.

MATERIALS AND METHODS

This animal study was IACUC approved. Seventeen male C57BL/6 mice were divided into control (n = 3) and experimental groups (n = 14) fed a methionine-deficient choline-deficient (MCD) diet to induce steatohepatitis. Livers underwent ex vivo diffusion-weighted MR imaging and ADC maps were calculated. A pathologist determined subjective scores of steatosis, classified from 0 to 3. Digital image analysis was used to determine percentage areas of steatosis. Graphs comparing ADC to subjective and digital image analysis (DIA) determinations of steatosis were plotted.

RESULTS

Subjective assessments of steatosis ranged up to values of 3 and DIA determined areas of steatosis to range up to approximately 16%. ADC values approximated 800 × 10(-6) mm(2) /s (range, 749-811 × 10(-6) mm(2) /s, mean 786 × 10(-6) mm(2) /s) in controls and 500 × 10(-6) mm(2) /s (range, 478-733 × 10(-6) mm(2) /s, mean 625 × 10(-6) mm(2) /s) in experimental mice. Moderate correlation between ADC and subjective scores of steatosis (R = -0.56) was observed. Strong correlation between ADC values and percentage areas of steatosis was between ADC values and percentage areas of steatosis was observed greater (R = -0.81) and very strong correlation was observed with the exclusion of a single outlying data point (R = -0.91).

CONCLUSION

Based on the comparison of ADC values and steatosis determinations by DIA, increasing degrees of steatosis are seen to result in decreased hepatic ADC values.

Metabolomic approach by 1H NMR spectroscopy of serum for the assessment of chronic liver failure in patients with cirrhosis

Assessment of chronic liver failure (CLF) in cirrhotic patients is needed to make therapeutic decisions. A biological score is usually performed, using the Model for End-Stage Liver Disease (MELD), to evaluate CLF. Nevertheless, MELD does not take into account metabolic perturbations produced by liver-function impairment. In contrast, metabolomics can investigate many metabolic perturbations within biological systems. The purpose of this study was to assess whether metabolomic profiles of serum, obtained by proton NMR spectroscopy from cirrhotic patients, are affected by the severity of CLF. An orthogonal projection to latent-structure analysis was performed to compare MELD scores and NMR spectra of 124 patients with cirrhosis. The statistical model obtained showed a good explained variance (R(2)X = 0.87 and R(2)Y = 0.86) and a good predictability (Q(2)Y = 0.64). Metabolomic profiles showed significant differences regarding various metabolites depending of severity of CLF: levels of high-density lipoprotein and phosphocholine resonances were significantly higher in patients with mild CLF compared to severe CLF. Other metabolites such as lactate, pyruvate, glucose, amino acids, and creatinine were significantly higher in patients with severe CLF than mild CLF. Our conclusion is that metabolomic NMR analysis provides new insights into metabolic processes related to the severity of hepatic function impairment in cirrhosis.

Long-TE 1H MRS suggests that liver fat is more saturated than subcutaneous and visceral fat

Cross-talk between adipose tissue and liver is disturbed in the metabolic syndrome. Moreover, the relative fatty acid composition of adipose and liver fat is poorly characterized. Long-TE (1)H MRS can determine the unsaturation and polyunsaturation of adipose tissue. The aim of this study was to use long-TE (1)H MRS to determine the composition of liver fat and its relation to adipose tissue composition. Sixteen subjects with increased liver fat (>5%) were recruited for the study. Using TE = 200  ms, we were able to resolve the olefinic (=CH, 5.3  ppm) and water (H(2)O, 4.7  ppm) resonances in liver spectra and to obtain a repeatable estimate of liver fat unsaturation (coefficient of variation, 2.3%). With TE = 135  ms, the diallylic (=C-CH(2)-C=, 2.8  ppm) resonance was detectable in subjects with a liver fat content above 15%. Long-TE (1)H MRS was also used to determine the unsaturation in subcutaneous (n = 16) and visceral (n = 11) adipose tissue in the same subjects. Liver fat was more saturated (double bonds per fatty acid chain, 0.812 ± 0.022) than subcutaneous (double bonds per fatty acid chain, 0.862 ± 0.022, p < 0.0004) or visceral (double bonds per fatty acid chain, 0.865 ± 0.033, p < 0.0004) fat. Liver fat unsaturation correlated with subcutaneous unsaturation (R = 0.837, p < 0.0001) and visceral unsaturation (R = 0.879, p < 0.0004). The present study introduces a new noninvasive method for the assessment of the composition of liver fat. The results suggest that liver fat is more saturated than subcutaneous or visceral adipose tissue, which may be attributed to differences in de novo lipogenesis.

In vivo 3T spectroscopic quantification of liver fat content in nonalcoholic fatty liver disease: Correlation with biochemical method and morphometry

BACKGROUND & AIMS

The clinical application of liver fat quantification has increased in recent years, paralleling the epidemic increase in nonalcoholic fatty liver disease. The aim of this study was to perform a diagnostic evaluation of spectroscopy by comparing its measurement of total lipid content with that from liver biopsies and morphometry in normal subjects and patients with nonalcoholic fatty liver disease.

METHODS

Patients with symptomatic cholelithiasis underwent 3T MR cholangiography with spectroscopic quantification of TLC. A laparoscopic cholecystectomy was performed on the day of admission, with liver samples taken during surgery. Microcolorimetric assessment quantified lipid content in liver samples and morphometric evaluation in stained slides. Statistical analysis included bivariate correlation, regression, and ROC analysis.

RESULTS

The study was conducted in 18 patients, 5 men (mean age, 35.2+/-11.03 years; range, 27-54 years) and 13 women (mean age, 46.77+/-11.77 years; range, 21-61 years). Using a cut-off value >5% for fat content, 8 patients presented with steatosis and 10 patients presented with normal liver fat content. A significant correlation was observed between fat spectroscopy and lipid content (r=0.876, p<0.001). A lower and non-significant correlation was observed between lipid content and morphometry (r=0.190, p>0.05).

CONCLUSIONS

The accuracy of spectroscopy in assessing fat concentration with a cut-off level of 7.48% was 100%. Spectroscopy showed a strong and significant correlation with lipid content. It may reliably replace liver biopsy for the assessment of liver fat content.

The importance of fatty liver disease in clinical practice

The worldwide obesity epidemic over the last 20 years has led to a dramatic increase in the prevalence of non-alcoholic fatty liver disease, the hepatic manifestation of the metabolic syndrome. Estimates of prevalence vary depending on the population studied and the methods used to assess hepatic fat content, but are commonly quoted as between 10 and 30% of the adults in the Western hemisphere. Fatty liver develops when fatty acid uptake and synthesis in the liver exceeds fatty acid oxidation and export as TAG. Studies of pathogenesis point to insulin resistance, lipotoxicity, oxidative stress and chronic inflammation being central to the development and progression of the disease. A proportion of individuals with fatty liver develop progressive disease, though large prospective longitudinal studies are lacking. Nevertheless, fatty liver is associated with increased all-cause and liver-related mortality compared with the general population. Management of fatty liver centres around lifestyle and dietary measures to induce controlled and sustained weight loss. Management of cardiovascular risk factors aims to reduce mortality, while certain dietary interventions have been shown to reduce steatosis and inflammation. Specific pharmacological treatments also show promise, but their use is not widespread. A multi-system and multi-disciplinary approach to the management of this disorder is proposed.