Histopathologic variability between the right and left lobes of the liver in morbidly obese patients undergoing Roux-en-Y bypass

Multiparametric magnetic resonance for the non-invasive diagnosis of liver disease

BACKGROUND & AIMS

With the increasing prevalence of liver disease worldwide, there is an urgent clinical need for reliable methods to diagnose and stage liver pathology. Liver biopsy, the current gold standard, is invasive and limited by sampling and observer dependent variability. In this study, we aimed to assess the diagnostic accuracy of a novel magnetic resonance protocol for liver tissue characterisation.

METHODS

We conducted a prospective study comparing our magnetic resonance technique against liver biopsy. The individual components of the scanning protocol were T1 mapping, proton spectroscopy and T2* mapping, which quantified liver fibrosis, steatosis and haemosiderosis, respectively. Unselected adult patients referred for liver biopsy as part of their routine care were recruited. Scans performed prior to liver biopsy were analysed by physicians blinded to the histology results. The associations between magnetic resonance and histology variables were assessed. Receiver-operating characteristic analyses were also carried out.

RESULTS

Paired magnetic resonance and biopsy data were obtained in 79 patients. Magnetic resonance measures correlated strongly with histology (r(s)=0.68 p<0.0001 for fibrosis; r(s)=0.89 p<0.001 for steatosis; r(s)=-0.69 p<0.0001 for haemosiderosis). The area under the receiver operating characteristic curve was 0.94, 0.93, and 0.94 for the diagnosis of any degree of fibrosis, steatosis and haemosiderosis respectively.

CONCLUSION

The novel scanning method described here provides high diagnostic accuracy for the assessment of liver fibrosis, steatosis and haemosiderosis and could potentially replace liver biopsy for many indications. This is the first demonstration of a non-invasive test to differentiate early stages of fibrosis from normal liver.

Wedge and needle liver biopsies show discordant histopathology in morbidly obese patients undergoing Roux-en-Y gastric bypass surgery

Background: Controversy exists over whether or not single-needle liver biopsies are sufficient to compare histological parameters in patients with non-alcoholic fatty liver disease.

Aims: To identify sampling variability, we biopsied four liver specimens per patient, based on biopsy size (needle vs wedge) and location (left vs right lobe), immediately prior to bariatric Roux-en-Y gastric bypass surgery.

Methods: Ten prospectively enrolled, morbidly obese patients underwent 40 laparoscopy-guided biopsies; two needle and two wedge from each of 16 left and 16 right liver lobes. The Kappa coefficient for concordance compared histological parameters from left and right lobe needle- and wedge biopsies. Wedge biopsies were considered our ‘Gold Standard’.

Results: Each patient had two wedge- and two needle liver biopsies. Kappa concordance between all needle and wedge biopsies from right and left lobes showed variability. Wedge- and needle liver biopsies from contralateral lobes had higher concordance with each other, compared to ipsilateral needle/wedge biopsy pairs. Contralateral wedge pairs had higher concordance than contralateral needle/needle pairs. There were no biopsy complications.

Conclusions: Wedge biopsy pairs had the best Kappa concordance but contralateral needle/needle biopsy pairs had good Kappa concordance. There were no complications from the 40 needle- and wedge liver biopsies, confirming the safety of laporoscopic multi-biopsy in both liver lobes.

Gd-EOB-DTPA-enhanced MRI for the assessment of liver function and volume in liver cirrhosis

OBJECTIVE

The aims of this study were to use dynamic hepatocyte-specific contrast-enhanced MRI to evaluate liver volume and function in liver cirrhosis, correlate the results with standard scoring models and explore the inhomogeneous distribution of liver function in cirrhotic livers.

METHODS

10 patients with liver cirrhosis and 20 healthy volunteers, serving as controls, were included. Hepatic extraction fraction (HEF), input relative blood flow and mean transit time were calculated on a voxel-by-voxel basis using deconvolutional analysis. Segmental and total liver volumes as well as segmental and total hepatic extraction capacity, expressed in HEFml, were calculated. An incongruence score (IS) was constructed to reflect the uneven distribution of liver function. The Mann-Whitney U-test was used for group comparison of the quantitative liver function parameters, liver volumes and ISs. Correlations between liver function parameters and clinical scores were assessed using Spearman rank correlation.

RESULTS

Patients had larger parenchymal liver volume, lower hepatocyte function and more inhomogeneous distribution of function compared with healthy controls.

CONCLUSION

The study demonstrates the non-homogeneous nature of liver cirrhosis and underlines the necessity of a liver function test able to compensate for the heterogeneous distribution of liver function in patients with diseased liver parenchyma.

ADVANCES IN KNOWLEDGE

The study describes a new way to quantitatively assess the hepatic uptake of gadoxetate or gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid in the liver as a whole as well as on a segmental level.

Real-time elastography for diagnosis of liver fibrosis in chronic hepatitis B

OBJECTIVES

The purpose of this study was to prospectively investigate the value of real-time ultrasound elastography for diagnosis of liver fibrosis in patients with chronic hepatitis B and to correlate the elastographic findings with histologic stages of liver fibrosis and blood parameters.

METHODS

Liver biopsies, blood testing, and real-time elastography were performed in 71 patients with chronic viral hepatitis B and liver cirrhosis. The ratio of the elastic strain of liver tissue to that of muscle tissue was determined and correlated with the histologic fibrosis stages and laboratory examination results.

RESULTS

There was a highly negative correlation between the elastic strain ratio and the histologic fibrosis stage (Spearman r = -0.702; P < .001). There was a high correlation observed between a decreasing elastic strain ratio and an increasing fibrosis stage. With substantial liver fibrosis (Scheuer score ≥ S2) and cirrhosis (S4) as diagnostic criteria, the areas under the receiver operating characteristic curves (AUCs) of the elastic strain ratios were 0.863 and 0.797, respectively. The AUC for substantial fibrosis was higher than the AUC for the blood parameters used to diagnose substantial liver fibrosis. Elastic strain ratio cutoff values of 1.10 and 0.60 were identified as diagnostic of substantial fibrosis and cirrhosis, respectively, with sensitivities of 77.8% and 50.0%, respectively, and specificities of 80.0% and 96.7%.

CONCLUSIONS

Real-time elastography is a new clinically promising and noninvasive method for quantitative assessment of liver fibrosis.

Hydrogen-1 MR spectroscopy for measurement and diagnosis of hepatic steatosis

OBJECTIVE

Hydrogen-1 MR spectroscopy ((1)H-MRS) is gaining acceptance as a noninvasive technique for assessment of hepatic steatosis, and the findings have been found to correlate closely with histopathologic grade. The aims of this study were to validate (1)H-MRS performed with a 3-T MRI system for quantifying hepatic steatosis and to determine threshold values of (1)H-MRS proton density fat fraction corresponding to standard histopathologic grade in patients undergoing diagnostic liver biopsy.

SUBJECTS AND METHODS

We conducted a prospective cross-sectional liver MRS study with 52 subjects undergoing diagnostic liver biopsy. The diagnostic accuracy of (1)H-MRS was evaluated with receiver operating characteristic curves.

RESULTS

The diagnostic accuracy of (1)H-MRS for hepatic steatosis was high with an area under the receiver operating characteristic curve of 0.94 (95% CI, 0.88-1.0). Results were similar for three (1)H-MRS measurements obtained at different locations in the liver, for two independent pathologists, and whether fibrosis was present or absent. One third of participants had elevated transaminase concentrations of unknown cause, and (1)H-MRS estimates of steatosis had perfect agreement with histopathologic grade in this group. Calculated (1)H-MRS proton density fat fraction thresholds for histologic grades were less than 17% for grade 0 or trace steatosis, 17-38.6% for grade 1, and greater than 38.6% for grade 2 or higher.

CONCLUSION

Hydrogen-1 MR spectroscopy is an effective, noninvasive technique that can be used to diagnose and quantify hepatic steatosis. Hydrogen-1 MR spectroscopy thresholds corresponded with histopathologic grades and may be useful in the workup of patients with elevated transaminase concentrations.

Liver fat accumulation may be dissociated from adiposity gain in ovariectomized rats

OBJECTIVE

The purpose of the present study was to establish a model of rats prone and resistant to intra-abdominal fat accumulation in response to ovariectomy (Ovx-P and Ovx-R) and to determine its relationship with molecular biomarkers.

DESIGN

Two experiments were conducted in which female rats were either sham-operated (Sham) or ovariectomized (Ovx). In the first experiment, ovariectomized rats were stratified into three tertiles based on intra-abdominal adipose tissue mass. To strengthen the Ovx-P/Ovx-R model, we conducted a second experiment in which the numbers of rats in each group were extended and in which different molecular markers were measured. At the end of a 6-8-week period, ovariectomized rats that displayed the lower abdominal fat accumulation (lower tertile) were labelled as Ovx-R and those in the upper tertile as Ovx-P.

RESULTS

Ovx-R rats displayed similar abdominal fat gain to Sham rats whereas Ovx-P rats depicted abdominal fat mass twice as high as that of Sham and Ovx-R rats. Despite the difference in abdominal adiposity, liver fat content was ~50% higher (p < 0.01) in both Ovx-R and Ovx-P rats compared to Sham rats. In addition, both Ovx-R and Ovx-P rats depicted higher HOMA-IR scores (p < 0.05) and lower (p < 0.01) hepatic gene expression of leptin receptor-b and -e, microsomal transfer protein (MTP), and diacylglycerol acyltransferase-2 (DGAT-2) compared to Sham rats.

CONCLUSION

The present findings indicate that estrogen withdrawal-induced hepatic steatosis and associated insulin resistance may be dissociated from abdominal fat accumulation and suggest that a decrease in leptin action through a down-regulation of leptin receptors and a decrease in very low density lipoprotein production through a down-regulation of MTP and DGAT-2 may be factors responsible for this observation in the absence of peripheral fat gain.

Lifestyle interventions for the treatment of non-alcoholic fatty liver disease in adults: a systematic review

Non-alcoholic fatty liver disease is a serious and growing clinical problem. Despite lifestyle modification, i.e. diet and physical activity, being the recommended therapy, there are currently no systematic evaluations of its efficacy. This review applies a systematic approach to evaluating lifestyle modifications studied to date. Medline (Pubmed), Scopus, and the Cochrane Controlled Trials Register were searched for studies and study groups assessing the effect of diet, physical activity, and/or exercise modification in adult populations with non-alcoholic fatty liver disease. The outcome markers of interest were indicators of steatosis, histological evidence of inflammation and fibrosis, and glucose control/insulin sensitivity. We identified 23 studies for inclusion; seven had control groups, but only six were randomised. Eleven groups received diet-only interventions, two exercise-only, and 19 diet and physical activity/exercise. Studies consistently showed reductions in liver fat and/or liver aminotransferase concentration, with the strongest correlation being with weight reduction. Of the 5 studies reporting changes in histopathology, all showed a trend towards reduction in inflammation, in 2 this was statistically significant. Changes in fibrosis were less consistent with only one study showing a significant reduction. The majority of studies also reported improvements in glucose control/insulin sensitivity following intervention. However, study design, definition of disease, assessment methods, and interventions varied considerably across studies. Lifestyle modifications leading to weight reduction and/or increased physical activity consistently reduced liver fat and improved glucose control/insulin sensitivity. Limited data also suggest that lifestyle interventions may hold benefits for histopathology.

Endpoints and clinical trial design for nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease is a common cause of chronic liver disease in the general population. Nonalcoholic steatohepatitis (NASH), the aggressive form of nonalcoholic fatty liver disease, is associated with an increased risk of liver-related mortality and cardiovascular disease. At present, a liver biopsy is the only generally acceptable method for the diagnosis of NASH and assessment of its progression toward cirrhosis. Although several treatments have shown evidence of efficacy in clinical trials of varying design, there are no approved treatments for NASH, and published trials are often too divergent to allow meaningful comparisons. There is thus a lack of established noninvasive, point-of-care diagnostics and approved treatment on one hand and a substantial population burden of disease on the other. These provide the rationale for developing consensus on key endpoints and clinical trial design for NASH.

CONCLUSION

This article summarizes the consensus arrived at a meeting of the American Association for the Study of Liver Diseases on the key endpoints and specific trial design issues that are germane for development of diagnostic biomarkers and treatment trials for NASH.

Histopathology of nonalcoholic fatty liver disease

Histological analysis of liver biopsies remains a standard against which other methods of assessment for the presence and amount of hepatic injury due to nonalcoholic fatty liver disease (NAFLD) are measured. Histological evaluation remains the sole method of distinguishing steatosis from advanced forms of NAFLD, i.e. nonalcoholic steatohepatitis (NASH) and fibrosis. Included in the lesions of NAFLD are steatosis, lobular and portal inflammation, hepatocyte injury in the forms of ballooning and apoptosis, and fibrosis. However, patterns of these lesions are as distinguishing as the lesions themselves. Liver injury in adults and children due to NAFLD may have different histological patterns. In this review, the rationale for liver biopsy, as well as the histopathological lesions, the microscopically observable patterns of injury, and the differential diagnoses of NAFLD and NASH are discussed.

Nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) significantly contributes to the morbidity and mortality of large proportions of the population across all age ranges, which will continue for the foreseeable future. Since NAFLD and nonalcoholic steatohepatitis were originally described, understanding of pathogenesis, relationships to insulin resistance and the metabolic syndrome, and histopathologic lesions has progressed. However, no clinical or imaging parameters can yet accurately predict inflammatory activity or fibrosis stage across the spectrum of disease. Liver needle biopsy interpretation remains essential in this role; liver biopsy evaluation is also needed for recognition of concurrent (or alternate) liver disease processes. Thus, an understanding of the histologic spectrum of findings in NAFLD and the methods of semiquantitative evaluations used are required for pathologists who sign out liver biopsies. This article describes histologic findings, and provides insights into the pathologic processes and clinical implications across the spectrum of NAFLD.

Nonalcoholic fatty liver disease/nonalcoholic steatohepatitis: histological diagnostic criteria and scoring systems

Nonalcoholic fatty liver disease (NAFLD) is recognized as the most common cause of chronic liver disease in western countries. NAFLD is etiologically associated with systemic and hepatic insulin resistance and is considered by many as the hepatic manifestation of the metabolic syndrome. NAFLD has a wide histological spectrum ranging from 'simple' steatosis to nonalcoholic steatohepatitis (NASH), which may progress to cirrhosis. Hepatocellular carcinoma may occur in NASH-related cirrhosis. The diagnosis of NAFLD/NASH is based on clinico-pathological criteria. Currently available noninvasive tests for the diagnosis of NASH lack specificity and sensitivity, so liver biopsy, despite its limitations, still remains the 'golden standard' for confirming or excluding NASH in a patient with chronically-elevated liver enzymes and image-detected steatosis. This review examines the currently used criteria for the histopathological diagnosis of NAFLD/NASH in adults and children and the relevant histological scoring systems.

Pathology of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a significant complication of obesity and is recognized as the hepatic manifestation of the metabolic syndrome. The process occurs in adults and children and is characterized by the presence of increased amounts of fat in the liver (steatosis). With inflammation, cell death and scarring (fibrosis), the process may result in end-stage liver disease, or be a precursor for hepatocellular carcinoma. Excess hepatic fat is now recognized as an independent marker for increased cardiovascular risk. Even though imaging studies and laboratory-based tests are accurate at detecting significant steatosis and/or advanced fibrosis, respectively, the diagnosis and characterization of NAFLD ultimately depend on histopathologic evaluation, as the parenchymal alterations that comprise the spectrum of injury in NAFLD include patterns as well as specific lesions. Histologic findings in children may differ from those in adults. In this Review, the histologic features that are diagnostic and discriminatory between steatosis and steatohepatitis, the significance of the distinction between steatosis and steatohepatitis, the types and locations of fibrosis, and the histologic variances between adult and pediatric NAFLD are discussed. Clinical advantages as well as potential drawbacks of liver biopsy are presented. Current pathophysiologic concepts relevant to histologic findings are discussed.

Histopathology of non-alcoholic fatty liver disease

Current imaging methodologies can detect steatosis with increasing accuracy but cannot detect inflammation or pre-cirrhotic fibrosis or remodeling of the liver parenchyma. Imaging also cannot assess types or localization of hepatic steatosis. With the increased use of rodents to study NAFLD/NASH, careful analysis or reading highlights the fact that liver tissue evaluations reported in many of the popular animal models of NAFLD/NASH often do not imitate many of the significant aspects of the human disease, despite similar terminology applied by investigators. This review will focus on the findings in human disease.

Methods for assessing intrahepatic fat content and steatosis

PURPOSE OF REVIEW

Intrahepatic fat content is increasingly being recognized as an integral part of metabolic dysfunction. This article reviews available methods for the assessment of hepatic steatosis.

RECENT FINDINGS

Apart from liver biopsy, there are several noninvasive radiologic modalities for evaluating nonalcoholic fatty liver disease. Ultrasonography, computed tomography, and traditional MRI remain largely qualitative methods for detecting mild to severe degrees of steatosis rather than quantitative methods for measuring liver fat content, even though novel attempts to collect objective quantitative information have recently been developed. Still, their sensitivity at mild degrees of steatosis is poor. Undoubtedly, most methodological advances have occurred in the field of MRI and magnetic resonance spectroscopy, which currently enable the accurate quantification of intrahepatic fat even at normal or near normal levels. Xenon computed tomography was also recently shown to offer another objective tool for the quantitative assessment of steatosis, although more validation studies are required.

SUMMARY

Several modalities can be used for measuring intrahepatic fat and assessing steatosis; the choice will ultimately depend on the intended use and available resources.

Liver biopsy in alcoholic and non-alcoholic steatohepatitis patients

Alcoholic liver disease and non-alcoholic liver disease share a similar histological spectrum that starts with 'simple' steatosis, and may be accompanied by inflammation. Alcoholic steatohepatitis and non-alcoholic steatohepatitis (NASH) are progressive forms of alcoholic liver disease and non-alcoholic liver disease, respectively, and can evolve into cirrhosis. The currently accepted minimum diagnostic criteria for steatohepatitis include steatosis, lobular inflammation and hepatocellular injury, but not fibrosis. Steatosis involving more than 5% of hepatocytes is required for the diagnosis of non-alcoholic fatty liver disease, but is not necessary for the diagnosis of alcoholic liver disease. Lobular inflammation is usually mild and frequently consists of a mixed, acute and chronic, inflammatory cell infiltrate composed of neutrophils and mononuclear cells. The presence of large numbers of neutrophils favors an alcoholic etiology. Hepatocellular injury in fatty liver disease usually occurs in the form of ballooning, but it can also present as apoptotic (acidophilic) bodies and lytic necrosis. The characteristic pattern of fibrosis in non-cirrhotic steatohepatitis is pericellular/perisinusoidal and is the result of deposition of collagen in the space of Disse. In both alcoholic steatohepatitis and NASH, sinusoidal collagen formation is the result of hepatic stellate cell activation that, in NASH, has been correlated with the grade of steatosis and fibrosis.

Effects of liver biopsy sample length and number of readings on sampling variability in nonalcoholic Fatty liver disease

BACKGROUND & AIMS

Liver biopsy is required to diagnose nonalcoholic steatohepatitis (NASH) in patients with suspected non-alcoholic fatty liver disease (NAFLD); recent studies suggested significant sampling variability. Using percutaneous liver biopsy samples from patients with suspected NAFLD, we examined the relationship between histological yield and length of biopsies, number of cores and number of independent readings.

METHODS

Three cores of liver tissue were collected, by percutaneous liver biopsy, from each of 50 patients suspected to have NAFLD. The diagnostic yield (percent with definite NASH) and other histological findings from 2 independent, blinded examinations of 2 cores and from all 3 cores combined were assessed.

RESULTS

Steatosis, lobular inflammation and fibrosis scores were significantly higher when 3 samples were analyzed, compared with 2. However, between groups, there were no significant differences in hepatocyte ballooning, proportion with an NAFLD activity score > or =4 or proportion with definite NASH (57% vs 61%, P = .3). The length of the biopsy sample correlated with percentage of patients found to have definite NASH (29%, 46%, 56%, and 65% in biopsies measuring <10 mm, 10-14 mm, 15-24 mm, and > or =25 mm, respectively; P < .0001). When biopsy specimens were read twice by the same pathologist, the composite of the 2 independent readings yielded a significantly higher yield for several histological features, compared with the first reading.

CONCLUSIONS

There is a significant relationship between histological yield and sample length and number of independent readings of liver biopsy samples. More studies are needed to optimize the strategy for liver biopsy, to more effectively assess histology in patients with suspected NAFLD.

Review article: diagnosis and treatment of non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is an increasingly prevalent condition affecting adults and children, leading to significant morbidity. It is often associated with the metabolic syndrome, although multiple pathogenetic mechanisms have been suggested. In the coming decades, it promises to be the leading cause of liver disease in industrial countries.

AIM

To provide a comprehensive, updated review of diagnosis and management of NAFLD and to appraise the evolution of new modalities in these areas.

METHODS

An Ovid MEDLINE search was performed to identify pertinent original research and review articles. Selected references in these articles were also evaluated.

RESULTS

The diagnosis of hepatic steatosis and steatohepatitis or non-alcoholic steatohepatitis (NASH) is not yet possible without liver biopsy. This is impractical given the large numbers affected by the condition. Current therapy has focused on improving insulin resistance and mediators of inflammation, factors probably associated with disease progression.

CONCLUSIONS

There are no proven non-invasive diagnostic modalities to distinguish NAFLD and NASH, but new biomarker panels are approximating the liver biopsy in accuracy. Therapeutic targets of drug development are in early stages, but a multifaceted approach will probably yield several treatment options in the years to come.

High prevalence of small intestinal bacterial overgrowth in patients with morbid obesity: a contributor to severe hepatic steatosis

BACKGROUND

With the increasing prevalence of obesity, non-alcoholic fatty liver disease (NAFLD) has become a major cause of liver diseases. Small intestinal bacterial overgrowth (SIBO) could be related to NAFLD. Our aim was to determine the prevalence of SIBO and its relationship with liver lesions in morbidly obese patients.

METHODS

A glucose hydrogen (H(2)) breath test (positive if fasting breath H(2) concentration > 20 ppm and/or an increase of > 10 ppm over baseline within the first 2 h) was performed in obese patients referred for bariatric surgery (body mass index [BMI] > 40 kg/m(2) or > 35 in association with comorbidities) and in healthy non-obese subjects. In obese patients, a surgical liver biopsy was performed.

RESULTS

One hundred and forty-six patients (129 women, age [mean+/-SE]: 40.7 +/- 11.4 years) were prospectively included in the study. The mean BMI was 46.1+/-6.4 kg/m(2). A liver biopsy was available in 137 patients and a breath test in 136. The frequency of positive breath tests was higher in obese patients (24/136, 17.1%) than in healthy subjects (1/40, 2.5%; P=0.031). In the univariate analysis, SIBO was not associated with clinical variables, but tended to be associated with more frequent severe hepatic steatosis (26.3 vs. 10.3%, P=0.127), whereas the frequency of sinusoidal or portal fibrosis, lobular necrosis and non-alcoholic steatohepatitis (NASH) were not different. In the multivariate analysis, SIBO (P=0.005) and the presence of a metabolic syndrome (P=0.006) were independent factors of severe hepatic steatosis.

CONCLUSION

In morbidly obese patients, bacterial overgrowth prevalence is higher than in healthy subjects and is associated with severe hepatic steatosis.