Hepatic MRI for fat quantitation: its relationship to fat morphology, diagnosis, and ultrasound

Short bowel syndrome: influence of nutritional therapy and incretin GLP1 on bone marrow adipose tissue

Energy deprivation leads to a decrease in white adipose tissue and bone mineral density (BMD), while simultaneously inducing the expansion of marrow adipose tissue (MAT). In short bowel syndrome (SBS), parenteral nutrition mitigates the deterioration of nutritional status, including decreases in MAT. Osteoporosis is, however, a frequent complication of SBS. The objective of our study here was to evaluate the association of fat deposit sites (subcutaneous and visceral adipose tissues: intrahepatic lipid (IHL) and MAT) and the incretin glucagon-like peptide 1 (GLP1) with BMD in individuals with SBS. MAT was negatively correlated with lumbar spine BMD in normal individuals, but not in those in the SBS group, who otherwise showed a positive correlation between MAT and GLP1. In addition, in individuals with SBS, IHL was negatively associated with lumbar spine BMD and positively associated with C-terminal telopeptide of type 1 collagen (a serum biomarker of bone turnover). Caloric maintenance in individuals with SBS, therefore, seems to positively affect the relationship between MAT and BMD, which may be modulated, at least in part, by GLP1.

Circulating levels of miR-122 and nonalcoholic fatty liver disease in pre-pubertal obese children

OBJECTIVES

The liver-specific miR-122 was proposed as biomarker for NAFLD in adults. Here, we investigated the relationship between miR-122 levels, parameters of liver metabolism and NAFLD in pre-pubertal obese children.

METHODS

Parameters of liver metabolism (ALT, AST and GGT) of three European cohorts were included (German cohort [n = 71; age: 11.53 ± 1.29 years; BMI z-score: 2.96 ± 0.64], Italian cohort [n = 45; age: 9.60 ± 2.11 years; BMI z-score: 3.57 ± 1.16], Slovenian cohort [n = 31; age: 7.53 ± 1.47 years; BMI z-score: 3.66 ± 0.88]). MiR-122 levels and CK18 concentrations were measured in fasting blood samples. In the German and Italian cohort, the diagnosis of NAFLD and grading of NAFLD was assessed by ultrasound.

RESULTS

NAFLD was diagnosed in n = 50 patients of the German cohort (29.6%) and in n = 29 patients (72.5%) of the Italian cohort. In all three cohorts, miR-122 was positively correlated with ALT and AST as well as with CK18 concentrations. MiR-122 levels were higher in children with NAFLD compared with healthy controls.

CONCLUSIONS

MiR-122 levels in pre-pubertal obese children could be a potential biomarker for paediatric NAFLD.

Alcohol consumption, but not smoking is associated with higher MR-derived liver fat in an asymptomatic study population

Background

The aim of our study was to determine the relation of alcohol consumption and cigarette smoking on continuous-measured hepatic fat fraction (HFF) in a population free of cardiovascular disease. We suggested a direct correlation of alcohol consumption with HFF and increased HFF in former smokers compared to current smokers.

Methods

Data from 384 subjects (mean age: 56 years, 58% men) of a population-based cohort study (KORA) were included in a cross-sectional design. Liver fat was assessed by 3 Tesla magnetic resonance imaging (MRI) using a multi-echo Dixon sequence and T2-corrected single voxel multi-echo spectroscopy (¹H-MRS). Smoking status was classified as never, former or current smoker and alcohol consumption as non-, moderate (0.1–39.9 g/day for men and 0.1–19.9 g/day for women), or heavy drinker (≥ 40 g/day for men and ≥ 20 g/day for women). Fatty liver disease was defined as HFF≥5.56%.

Results

Average HFF was 8.8% by ¹H-MRS and 8.5% by MRI. Former smokers showed a higher HFF (MRI: β = 2.64; p = 0.006) and a higher FLD prevalence (MRI: OR = 1.91; p = 0.006) compared to never smokers. Current smokers showed decreased odds for FLD measured by ¹H-MRS after multivariable adjustment (OR = 0.37; p = 0.007) with never smoker as reference. Heavy drinking was positively associated with HFF (¹H-MRS: β = 2.99; p = 0.003) and showed highest odds for FLD (¹H-MRS: OR = 3.05; p = 0.008) with non-drinker as reference. Moderate drinking showed a positive association with HFF (¹H-MRS: β = 1.54; p = 0.061 and MRI: β = 1.75; p = 0.050).

Conclusions

Our data revealed lowest odds for FLD in current smokers, moderate drinkers showing higher HFF than non-drinkers and heavy drinkers showing highest HFF and odds for FLD. These findings partly conflict with former literature and underline the importance of further studies to investigate the complex effects on liver metabolism.

Role of imaging-based biomarkers in NAFLD: Recent advances in clinical application and future research directions

Non-alcoholic fatty liver disease (NAFLD) is a major public health problem afflicting approximately one billion individuals worldwide. Liver biopsy is considered the gold standard for assessment of liver disease severity in patients with NAFLD. However, it is invasive, has high inter-observer variability, and is associated with adverse effects, including pain, infection and, albeit rarely, death. It is also impractical because of the large number of individuals who have NAFLD. Therefore, tools to non-invasively assess disease severity in NAFLD are urgently needed. Over the last two decades, tremendous advances have been made in the assessment of NAFLD by non-invasive imaging. In this review, we will discuss the different non-invasive imaging modalities available to quantify liver fat and liver fibrosis. We will also discuss the limitations of current modalities to detect the progressive form for NAFLD, termed non-alcoholic steatohepatitis. Finally, we will discuss the comparative efficacy of various imaging-based elastographic modalities for detection of advanced fibrosis or cirrhosis, as well as their diagnostic characteristics.

The Use of Liver Biopsy in Nonalcoholic Fatty Liver Disease: When to Biopsy and in Whom

Nonalcoholic fatty liver disease (NAFLD) is a common liver disorder that can be divided into benign steatosis or nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). Elastography and scoring systems based on clinical features and routine biochemical testing can be used to assess fibrosis in patients with NAFLD. Patients with fibrosis are thought to have NASH. However, only a liver biopsy can reliably diagnose NAFLD and differentiate NAFL from NASH. Because medical therapy for NASH is not available, it is not necessary to perform a liver biopsy in all patients. Patients suspected of having NASH should undergo liver biopsy.

NAFL screening score: A basic score identifying ultrasound-diagnosed non-alcoholic fatty liver

BACKGROUND

Several non-invasive diagnostic scores for non-alcoholic fatty liver (NAFL) have been developed, but the clinical application is limited because of their complexity.

AIM

To develop and validate an easy-to-calculate scoring system to identify ultrasound-diagnosed NAFL.

METHODS

48,489 patients from 2 centers were included in this study. Multivariable logistic regression models were employed for model development. Ultrasonography was applied to diagnose NAFL. The selected variables were assigned an integer score proportional to the estimated coefficient from the logistic regression analysis, namely NAFL Screening Score (NSS). The ability of the NSS to identify NAFL was assessed by analyzing the area under the receiver operating characteristic curve (AUROC) and was tested in an independent validation cohort. Additionally, the performance of NSS was compared with existing models.

RESULTS

NSS was developed as a basic score comprising of age, body mass index (BMI), triglyceride (TG), ALT/AST, fasting plasma glucose (FPG) and uric acid (UA) in both sexes. NSS showed a relatively good discriminative power (AUROC=0.825 for males, 0.861 for females in the validation cohort) in comparison with other models. The optimal cut-off point was 32 for males and 29 for females.

CONCLUSION

We developed and validated NSS, an easy-to-use score sheet identify ultrasound-diagnosed NAFL. NSS may be clinically useful for initial diagnosing NAFL.

A prospective comparative assessment of the accuracy of the FibroScan in evaluating liver steatosis

Background/aims

Recent studies have demonstrated the utility of the FibroScan^® device in diagnosing liver steatosis, but its usefulness has not been thoroughly appraised. We investigated the usefulness of the controlled attenuation parameter (CAP) in detecting and quantifying liver steatosis.

Methods

A prospective analysis was applied to 79 chronic liver disease patients who underwent a liver biopsy, a FibroScan investigation, ultrasonography, and hepatic steatosis index (HSI). The presence and degree of steatosis as measured by the FibroScan device, ultrasonography and HSI were compared with the results for the liver biopsy tissue.

Results

There was substantial concordance between the liver biopsy results and the CAP as evaluated by the kappa (κ) index test for detecting liver steatosis (κ_CAP = 0.77, P<0.001; κ_{ultrasonography} = 0.60, P<0.001; κ_HSI = 0.47, P<0.001). The areas under the receiver operating characteristic curve (AUROCs) of the CAP, ultrasonography, and HSI were 0.899 [95% confidence interval (CI) = 0.826–0.972)], 0.859 (95% CI = 0.779–0.939), and 0.766 (95% CI = 0.655–0.877), respectively. The optimal CAP cutoff value for differentiating between normal and hepatic steatosis was 247 dB/m, which produced sensitivity and specificity values of 91.9% and 85.7%, respectively, as well as a positive predictive value of 85.0% and a negative predictive value of 92.3%.

Conclusion

The CAP produces results that are highly concordant with those of a liver biopsy in detecting steatosis. Therefore, the CAP is a noninvasive and reliable tool for evaluating liver steatosis, even in the early stages.

Imaging of hepatic toxicity of systemic therapy in a tertiary cancer centre: chemotherapy, haematopoietic stem cell transplantation, molecular targeted therapies, and immune checkpoint inhibitors

The purpose of this review is to familiarise radiologists with the spectrum of hepatic toxicity seen in the oncology setting, in view of the different systemic therapies used in cancer patients. Drug-induced liver injury can manifest in various forms, and anti-neoplastic agents are associated with different types of hepatotoxicity. Although chemotherapy-induced liver injury can present as hepatitis, steatosis, sinusoidal obstruction syndrome, and chronic parenchymal damages, molecular targeted therapy-associated liver toxicity ranges from mild liver function test elevation to fulminant life-threatening acute liver failure. The recent arrival of immune checkpoint inhibitors in oncology has introduced a new range of immune-related adverse events, with differing mechanisms of liver toxicity and varied imaging presentation of liver injury. High-dose chemotherapy regimens for haematopoietic stem cell transplantation are associated with sinusoidal obstruction syndrome. Management of hepatic toxicity depends on the clinical scenario, the drug in use, and the severity of the findings. In this article, we will (1) present the most common types of oncological drugs associated with hepatic toxicity and associated liver injuries; (2) illustrate imaging findings of hepatic toxicities and the possible differential diagnosis; and (3) provide a guide for management of these conditions.

Imaging patterns and focal lesions in fatty liver: a pictorial review

Non-alcoholic fatty liver disease is the most common cause of chronic liver disease and affects nearly one-third of US population. With the increasing trend of obesity in the population, associated fatty change in the liver will be a common feature observed in imaging studies. Fatty liver causes changes in liver parenchyma appearance on imaging modalities including ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) and may affect the imaging characteristics of focal liver lesions (FLLs). The imaging characteristics of FLLs were classically described in a non-fatty liver. In addition, focal fatty change and focal fat sparing may also simulate FLLs. Knowledge of characteristic patterns of fatty change in the liver (diffuse, geographical, focal, subcapsular, and perivascular) and their impact on the detection and characterization of FLL is therefore important. In general, fatty change may improve detection of FLLs on MRI using fat suppression sequences, but may reduce sensitivity on a single-phase (portal venous) CT and conventional ultrasound. In patients with fatty liver, MRI is generally superior to ultrasound and CT for detection and characterization of FLL. In this pictorial essay, we describe the imaging patterns of fatty change in the liver and its effect on detection and characterization of FLLs on ultrasound, CT, MRI, and PET.

Randomised clinical trial: the efficacy and safety of oltipraz, a liver X receptor alpha-inhibitory dithiolethione in patients with non-alcoholic fatty liver disease

BACKGROUND

Oltipraz is a synthetic dithiolethione with an antisteatotic effect by inhibiting the activity of liver X receptor alpha (LXR-α). Recent studies demonstrated the disruptive role of oltipraz on LXR-α-dependent lipogenesis in hepatocytes and a high-fat diet mouse model.

AIM

To evaluate the efficacy and safety of oltipraz for reducing liver fat in subjects with non-alcoholic fatty liver disease (NAFLD).

METHODS

We performed a multicentre, double-blind, placebo-controlled, phase II study. Subjects with a liver fat >20% and hypertransaminasemia were randomised to the three groups: placebo (n = 22), 30 mg of oltipraz (n = 22) or 60 mg of oltipraz (n = 24) twice daily for 24 weeks. Changes in the liver fat from baseline to 24 weeks quantified using magnetic resonance spectroscopy were the primary outcome.

RESULTS

Compared with the placebo group (-3.2 ± 11.1%), absolute changes in the liver fat content increased in a dose-dependent manner: -7.7 ± 7.0% and -13.9 ± 10.7% for the low-dose and high-dose groups (P = 0.13 and P < 0.01). Per cent reduction in the liver fat content was also significantly greater in the high-dose group than in the placebo group (-34.6 ± 29.4% vs. -0.6 ± 62.9%, P = 0.046). Body mass indices (-1.0 ± 0.9% vs. -0.5 ± 1.4%, P = 0.04) significantly decreased in the high-dose group compared to the placebo group. However, absolute changes in insulin resistance, liver enzymes, lipids and cytokines were not significantly different among groups. The incidence of adverse events was comparable among groups.

CONCLUSIONS

Twenty-four-week oltipraz treatment significantly reduced the liver fat content in patients with NAFLD. Clinicaltrials.gov (NCT01373554).

Race/ethnic and sex disparities in the non-alcoholic fatty liver disease-abdominal aortic calcification association: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND AIMS

This study investigated the associations of non-alcoholic fatty liver disease (NAFLD) and abdominal aortic calcification (AAC) volume and density, and whether these relationships vary by race/ethnicity and/or sex, information that are limited in current literature.

METHODS

We studied 1004 adults from the Multi-Ethnic Study of Atherosclerosis to assess the relationship between NAFLD (liver-to-spleen ratio <1) and the following measures of AAC: presence (volume score >0, using Poisson regression); change in volume score (increasing vs. no change, using Poisson regression); and morphology (volume and density score, where volume score >0, using linear regression); and interaction by race/ethnicity and sex.

RESULTS

Among Blacks, those with NAFLD had greater prevalence for AAC compared to Whites regardless of sex (Prevalence Ratio [PR] = 1.41, CI = 1.15-1.74, p-interaction = 0.02). Concurrent interaction by race/ethnicity and sex was found comparing Chinese and Blacks to Whites (p-interaction = 0.017 and 0.042, respectively) in the association between NAFLD and the prevalence of increasing AAC. Among women, this relationship was inverse among Chinese (PR = 0.59, CI = 0.28-1.27), and positive among Whites (PR = 1.34, CI = 1.02-1.76). This finding was reversed evaluating the men counterpart. Black men also had a positive association (PR = 1.86, CI = 1.29-2.70), which differed from the inverse relationship among White men, and was greater compared to Black women (PR = 1.45, CI = 1.09-1.94). NAFLD was unrelated to AAC morphology.

CONCLUSIONS

NAFLD was related to the presence of AAC, however, limited to Blacks. Significant concurrent interaction by race/ethnicity (Chinese and Blacks vs. Whites) and sex was found in the relationship between NAFLD and increasing AAC. These findings suggest disparities in the pathophysiologic pathways in which atherosclerosis develops.

The triglyceride and glucose index (TyG) is an effective biomarker to identify nonalcoholic fatty liver disease

Background

The triglyceride and glucose index (TyG) has been proposed as a marker of insulin resistance. We aimed to investigate the ability of TyG, through comparing with the predictive value of alanine aminotransferase (ALT), to identify individuals at risk for nonalcoholic fatty liver disease (NAFLD).

Methods

A cross-sectional study was conducted in a Chinese health examination cohort of 10 761 people aged above 20 years. NAFLD was diagnosed by ultrasonography.

Results

Compared with the participants in the lowest quartile of TyG, the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for NAFLD were 1.8 (1.5–2.1), 3.0 (2.5–3.5), and 6.3 (5.3–7.5) for those in the second, the third, and the fourth quartile of TyG, whereas the corresponding ORs (95% CI) for NAFLD were 1.5 (1.3–1.7), 1.9 (1.6–2.2), and 3.1 (2.6–3.7) for the upper three quartiles of ALT. These results suggested that TyG was superior to ALT in association with NAFLD risk. According to the ROC analysis, the optimal cut-off point of TyG for NAFLD was 8.5 and the area under the ROC curve (AUC) was 0.782 (95% CI 0.773–0.790), with 72.2 and 70.5% sensitivity and specificity, respectively. The AUC of TyG was larger than that of ALT (0.715 (95% CI 0.705–0.725), P for difference <0.0001), whereas the largest AUC was obtained when adding TyG to ALT (0.804 (95% CI 0.795–0.812), P for difference <0.0001).

Conclusions

TyG is effective to identify individuals at risk for NAFLD. A TyG threshold of 8.5 was highly sensitive for detecting NAFLD subjects and may be suitable as a diagnostic criterion for NAFLD in Chinese adults.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-017-0409-6) contains supplementary material, which is available to authorized users.

Hepatic steatosis and fibrosis: Non-invasive assessment

Chronic liver disease is a major cause of morbidity and mortality worldwide and usually develops over many years, as a result of chronic inflammation and scarring, resulting in end-stage liver disease and its complications. The progression of disease is characterised by ongoing inflammation and consequent fibrosis, although hepatic steatosis is increasingly being recognised as an important pathological feature of disease, rather than being simply an innocent bystander. However, the current gold standard method of quantifying and staging liver disease, histological analysis by liver biopsy, has several limitations and can have associated morbidity and even mortality. Therefore, there is a clear need for safe and non-invasive assessment modalities to determine hepatic steatosis, inflammation and fibrosis. This review covers key mechanisms and the importance of fibrosis and steatosis in the progression of liver disease. We address non-invasive imaging and blood biomarker assessments that can be used as an alternative to information gained on liver biopsy.

Clinical significance of serum alanine aminotransferase and lifestyle intervention in children with nonalcoholic fatty liver disease

Purpose

This study aimed to investigate the clinical significance of serum alanine aminotransferase (ALT) levels in children with nonalcoholic fatty liver disease (NAFLD) and the effect of lifestyle intervention on NAFLD.

Methods

The clinical data of 86 children diagnosed with NAFLD were reviewed retrospectively. Forty-six patients belonged to the elevated ALT group and 40 to the normal ALT group. The clinical parameters of patients with NAFLD were also compared based on the status of ALT levels after lifestyle intervention.

Results

Patients with elevated ALT had significantly higher body mass index (BMI) scores than those with normal ALT (P<0.05). Of all the patients with elevated ALT, 89% exhibited moderate or severe degree of fatty change in the liver on ultrasonographic examination, whereas most patients with normal ALT exhibited mild or moderate degree changes. Liver biopsy was performed in 15 children with elevated ALT and all showed mild histological changes. Of all patients with elevated ALT, 49% achieved normal ALT levels after lifestyle intervention. Those with more severe histological changes tended to have continuously increasing ALT levels. There was no correlation between the normalization of posttreatment ALT level and BMI, as well as ultrasonographic findings at diagnosis.

Conclusion

ALT elevation in NAFLD is highly associated with higher BMI scores and more severe degree of fatty changes on ultrasonographic examination. Lifestyle intervention can significantly improve ALT in children with NAFLD. The degree of histologic changes appears to be a predictor of the treatment response to NAFLD.

Stereological Analysis of Liver Biopsy Histology Sections as a Reference Standard for Validating Non-Invasive Liver Fat Fraction Measurements by MRI

Background and Aims

Validation of non-invasive methods of liver fat quantification requires a reference standard. However, using standard histopathology assessment of liver biopsies is problematical because of poor repeatability. We aimed to assess a stereological method of measuring volumetric liver fat fraction (VLFF) in liver biopsies and to use the method to validate a magnetic resonance imaging method for measurement of VLFF.

Methods

VLFFs were measured in 59 subjects (1) by three independent analysts using a stereological point counting technique combined with the Delesse principle on liver biopsy histological sections and (2) by three independent analysts using the HepaFat-Scan^® technique on magnetic resonance images of the liver. Bland Altman statistics and intraclass correlation (IC) were used to assess the repeatability of each method and the bias between the methods of liver fat fraction measurement.

Results

Inter-analyst repeatability coefficients for the stereology and HepaFat-Scan^® methods were 8.2 (95% CI 7.7–8.8)% and 2.4 (95% CI 2.2–2.5)% VLFF respectively. IC coefficients were 0.86 (95% CI 0.69–0.93) and 0.990 (95% CI 0.985–0.994) respectively. Small biases (≤3.4%) were observable between two pairs of analysts using stereology while no significant biases were observable between any of the three pairs of analysts using HepaFat-Scan^®. A bias of 1.4±0.5% VLFF was observed between the HepaFat-Scan^® method and the stereological method.

Conclusions

Repeatability of the stereological method is superior to the previously reported performance of assessment of hepatic steatosis by histopathologists and is a suitable reference standard for validating non-invasive methods of measurement of VLFF.

Comparative accuracy of CT, dual-echo MRI and MR spectroscopy for preoperative liver fat quantification in living related liver donors

Background:

It is of significant importance to assess the extent of hepatic steatosis in living donor liver transplant (LDLT) surgery to ensure optimum graft regeneration as well as donor safety.

Aim:

To establish the accuracy of non-invasive imaging methods including computed tomography (CT), dual-echo in- and opposed-phase magnetic resonance imaging (MRI), and MR spectroscopy (MRS) for quantification of liver fat content (FC) in prospective LDLT donors with histopathology as reference standard.

Settings and Design:

This retrospective study was conducted at our institution on LDLT donors being assessed for biliary and vascular anatomy depiction by Magnetic Resonance Cholangiopancreatography (MRCP) and CT scan, respectively, between July 2013 and October 2014.

Materials and Methods:

Liver FC was measured in 73 donors by dual-echoT1 MRI and MRS. Of these, CT liver attenuation index (LAI) values were available in 62 patients.

Statistical Analysis:

CT and MRI FC were correlated with histopathological reference standard using Spearman correlation coefficient. Sensitivity, specificity, positive predictive value, negative predicative value, and positive and negative likelihood ratios with 95% confidence intervals were obtained.

Results:

CT LAI, dual-echo MRI, and MRS correlated well with the histopathology results (r = 0.713, 0.871, and 0.882, respectively). An accuracy of 95% and 96% was obtained for dual-echo MRI and MRS in FC estimation with their sensitivity being 97% and 94%, respectively. False-positive rate, positive predictive value (PPV), and negative predicative value (NPV) were 0.08, 0.92, and 0.97, respectively, for dual-echo MRI and 0.03, 0.97, and 0.95, respectively, for MRS. CT LAI method of fat estimation has a sensitivity, specificity, PPV, and NPV of 73%, 77.7%, 70.4%, and 80%, respectively.

Conclusion:

Dual-echo MRI, MRS, and CT LAI are accurate measures to quantify the degree of hepatic steatosis in LDLT donors, thus reducing the need for invasive liver biopsy and its associated complications. Dual-echo MRI and MRS results correlate better with histological results in the study, as compared to CT LAI method for fat quantification.

A "systems medicine" approach to the study of non-alcoholic fatty liver disease

The prevalence of fatty liver (steatosis) in the general population is rapidly increasing worldwide. The progress of knowledge in the physiopathology of fatty liver is based on the systems biology approach to studying the complex interactions among different physiological systems. Similarly, translational and clinical research should address the complex interplay between these systems impacting on fatty liver. The clinical needs drive the applications of systems medicine to re-define clinical phenotypes, assessing the multiple nature of disease susceptibility and progression (e.g. the definition of risk, prognosis, diagnosis criteria, and new endpoints of clinical trials). Based on this premise and in light of recent findings, the complex mechanisms involved in the pathology of fatty liver and their impact on the short- and long-term clinical outcomes of cardiovascular, metabolic liver diseases associated with steatosis are presented in this review using a new "systems medicine" approach. A new data set is proposed for studying the impairments of different physiological systems that have an impact on fatty liver in different subsets of subjects and patients.

Quantification of liver fat: A comprehensive review

Fat accumulation in the liver causes metabolic diseases such as obesity, hypertension, diabetes or dyslipidemia by affecting insulin resistance, and increasing the risk of cardiac complications and cardiovascular disease mortality. Fatty liver diseases are often reversible in their early stage; therefore, there is a recognized need to detect their presence and to assess its severity to recognize fat-related functional abnormalities in the liver. This is crucial in evaluating living liver donors prior to transplantation because fat content in the liver can change liver regeneration in the recipient and donor. There are several methods to diagnose fatty liver, measure the amount of fat, and to classify and stage liver diseases (e.g. hepatic steatosis, steatohepatitis, fibrosis and cirrhosis): biopsy (the gold-standard procedure), clinical (medical physics based) and image analysis (semi or fully automated approaches). Liver biopsy has many drawbacks: it is invasive, inappropriate for monitoring (i.e., repeated evaluation), and assessment of steatosis is somewhat subjective. Qualitative biomarkers are mostly insufficient for accurate detection since fat has to be quantified by a varying threshold to measure disease severity. Therefore, a quantitative biomarker is required for detection of steatosis, accurate measurement of severity of diseases, clinical decision-making, prognosis and longitudinal monitoring of therapy. This study presents a comprehensive review of both clinical and automated image analysis based approaches to quantify liver fat and evaluate fatty liver diseases from different medical imaging modalities.

[Techniques for quantification of liver fat in risk stratification of diabetics]

CLINICAL/METHODICAL ISSUE

Fatty liver disease plays an important role in the development of type 2 diabetes. Accurate techniques for detection and quantification of liver fat are essential for clinical diagnostics.

STANDARD RADIOLOGICAL METHODS

Chemical shift-encoded magnetic resonance imaging (MRI) is a simple approach to quantify liver fat content.

METHODICAL INNOVATIONS

Liver fat quantification using chemical shift-encoded MRI is influenced by several bias factors, such as T2* decay, T1 recovery and the multispectral complexity of fat.

PERFORMANCE

The confounder corrected proton density fat fraction is a simple approach to quantify liver fat with comparable results independent of the software and hardware used.

ACHIEVEMENTS

The proton density fat fraction is an accurate biomarker for assessment of liver fat.

PRACTICAL RECOMMENDATIONS

An accurate and reproducible quantification of liver fat using chemical shift-encoded MRI requires a calculation of the proton density fat fraction.

Caring for children with NAFLD and navigating their care into adulthood

NAFLD is the most common chronic liver disease in children and adults, with its prevalence closely associated with obesity and other features of the metabolic syndrome. As young adults with NAFLD transition from the paediatric care environment to adult services, establishing a coordinated model of transition to ensure ongoing and appropriate care is critical. Enabling a smooth transfer begins with an understanding of the key differences between paediatric and adult NAFLD as well as the psychosocial factors that affect older adolescents. This Review summarizes the literature on paediatric NAFLD from the past two decades with a focus on the differences in epidemiology, pathology, pathophysiology and treatment that are relevant to clinicians who transition paediatric patients to adult care. An integrated model, which employs a team of adult and paediatric providers who can address the psychosocial, cognitive and logistical challenges of transition, provides the best opportunity for a seamless and coordinated transfer to adult care.

The severity of steatosis influences liver stiffness measurement in patients with nonalcoholic fatty liver disease

In nonalcoholic fatty liver disease, the influence of severity of steatosis on liver stiffness measurement (LSM) is poorly studied and still debated. We assessed the impact of steatosis severity and its ultrasonographic (US) sign, severe bright liver echo pattern, on LSM values and on transient elastography accuracy for the diagnosis of liver fibrosis in a cohort of consecutive patients with nonalcoholic fatty liver disease. Patients (n = 253) were assessed by clinical, US, and histological (Kleiner score) features. Transient elastography was performed using the M probe. Among patients with low amounts of fibrosis (F0-F1 and F0-F2), median LSM values, expressed in kilopascals, were significantly higher in subjects with severe steatosis (≥66% at liver biopsy) compared to those without (F0-F1 6.9 versus 5.8, P = 0.04; F0-F2 7.4 versus 6.0, P = 0.001) as well as in patients with severe bright liver echo pattern on US compared to their counterparts (F0-F1 7.3 versus 5.6, P = 0.001; F0-F2 7.6 versus 6.0, P < 0.001). In subjects without significant fibrosis (F0-F1) and without severe fibrosis (F0-F2), a higher rate of false-positive LSM results was observed in patients with steatosis ≥66% compared to those without (F0-F1 23.6% versus 14.9%, F0-F2 33.3% versus 13.2%) and in patients with severe bright liver echo pattern on US (F0-F1 22.2% versus 15.4%, F0-F2 28.8% versus 15.6%) compared to their counterparts.

CONCLUSIONS

In patients with nonalcoholic fatty liver disease, the presence of severe steatosis, detected by histology or by US, should always be taken into account in order to avoid overestimations of liver fibrosis assessed by transient elastography.

Imaging methods for analyzing body composition in human obesity and cardiometabolic disease

Advances in the technological qualities of imaging modalities for assessing human body composition have been stimulated by accumulating evidence that individual components of body composition have significant influences on chronic disease onset, disease progression, treatment response, and health outcomes. Importantly, imaging modalities have provided a systematic method for differentiating phenotypes of body composition that diverge from what is considered normal, that is, having low bone mass (osteopenia/osteoporosis), low muscle mass (sarcopenia), high fat mass (obesity), or high fat with low muscle mass (sarcopenic obesity). Moreover, advances over the past three decades in the sensitivity and quality of imaging not just to discern the amount and distribution of adipose and lean tissue but also to differentiate layers or depots within tissues and cells is enhancing our understanding of distinct mechanistic, metabolic, and functional roles of body composition within human phenotypes. In this review, we focus on advances in imaging technologies that show great promise for future investigation of human body composition and how they are being used to address the pandemic of obesity, metabolic syndrome, and diabetes.

Sonographically measured suprailiac adipose tissue is a useful predictor of non-alcoholic fatty liver disease in obese children and adolescents

OBJECTIVE

The objective of the present study was to identify ultrasonographic and anthropometric parameters that are highly associated with the presence of non-alcoholic fatty liver disease (NAFLD) in overweight children and adolescents.

METHODS

A total of 447 overweight children and adolescents (body mass index, 32.4 ± 5.2 kg m(-2) ; mean age, 14.2 ± 1.9 years; range 10.1-20.3 years) were analysed. Subjects underwent ultrasound examination of the liver as well as ultrasonographic measurement of the amount of adipose tissue overlying the biceps brachii and triceps brachii muscles, and of subscapular, suprailiac and abdominal subcutaneous adipose tissue and intra-abdominal depth. Anthropometric parameters such as body mass index, waist and hip circumference were documented.

RESULTS

The prevalence of NAFLD was 27.1%; it was significantly associated with the above-cited anthropometric parameters (P < 0.001). Ultrasonographic findings identified a significant association between NAFLD and the amount of subscapular, suprailiac and abdominal subcutaneous adipose tissue (P < 0.001) as well as between NAFLD and intra-abdominal depth (P < 0.001). Stepwise logistic regression analysis showed only intra-abdominal depth for both gender and the deposit of subcutaneous suprailiac adipose tissue in females to be independent predictors of NAFLD.

CONCLUSIONS

In overweight children and adolescents, we identified intra-abdominal depth for both gender and the ultrasonographically easily determined subcutaneous suprailiac adipose tissue in females as independent predictor of NAFLD.

The Relationship of Fat Distribution and Insulin Resistance with Lumbar Spine Bone Mass in Women

Bone marrow harbors a significant amount of body adipose tissue (BMAT). While BMAT might be a source of energy for bone modeling and remodeling, its increment can also represent impairment of osteoblast differentiation. The relationship between BMAT, bone mass and insulin sensitivity is only partially understood and seems to depend on the circumstances. The present study was designed to assess the association of BMAT with bone mineral density in the lumbar spine as well as with visceral adipose tissue, intrahepatic lipids, HOMA-IR, and serum levels of insulin and glucose. This cross-sectional clinical investigation included 31 non-diabetic women, but 11 had a pre-diabetes status. Dual X-ray energy absorptiometry was used to measure bone mineral density and magnetic resonance imaging was used to assess fat deposition in BMAT, visceral adipose tissue and liver. Our results suggest that in non-diabetic, there is an inverse relationship between bone mineral density in lumbar spine and BMAT and a trend persists after adjustment for weight, age, BMI and height. While there is a positive association between visceral adipose tissue and intrahepatic lipids with serum insulin levels, there is no association between BMAT and serum levels of insulin. Conversely, a positive relationship was observed between BMAT and serum glucose levels, whereas this association was not observed with other fat deposits. These relationships did not apply after adjustment for body weight, BMI, height and age. The present study shows that in a group of predominantly non-obese women the association between insulin resistance and BMAT is not an early event, as occurs with visceral adipose tissue and intrahepatic lipids. On the other hand, BMAT has a negative relationship with bone mineral density. Taken together, the results support the view that bone has a complex and non-linear relationship with energy metabolism.

Development of non-alcoholic fatty liver disease scoring system among adult medical check-up patients: a large cross-sectional and prospective validation study

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the community. However, NAFLD remains undiagnosed in most people with limited access to imaging facilities in most developing countries.

OBJECTIVE

To examine the prevalence of NAFLD and to develop the risk scoring model for predicting the presence of NAFLD among adult medical check-up patients.

METHOD

A large prospective cross-sectional study was conducted among medical check-up patients who underwent transabdominal ultrasound examination between January and December 2013 in Medistra Hospital, Jakarta. Data were obtained from the patients' medical records. Logistic regression analyses were undertaken to identify the best combination of risk factors for predicting fatty liver using the backward (likelihood ratio) approach. The adjusted odds ratio and 95% confidence interval were estimated using the logistic regression coefficient. The prediction model was assessed using the receiver operating characteristic curve and the Hosmer-Lemeshow goodness-of-fit test and was validated on a new, prospective cohort. Statistical analysis was done using SPSS version 17.

RESULTS

A total of 1,054 cases was included in this study. Fatty liver was present in 538 (51.0%) patients. Bivariate analyses found associations among fatty liver and several risk factors. Six risk factors were incorporated to build the final prediction model. All scores were summed up to obtain the total score. A probability equation was developed by applying linear regression analysis on the total score. The prediction model had good diagnostic performance with an area under the receiver operating characteristic curve =0.833 (95% confidence interval =0.809-0.857). The Hosmer-Lemeshow goodness-of-fit P-value was 0.232, which indicated the appropriateness of the logistic regression model to predict fatty liver. On the validation set, the scoring system proved to be moderately accurate and can potentially be applied to larger population setting.

CONCLUSION

The presence of fatty liver in NAFLD patients can be predicted using our proposed fatty liver scoring system.

Non-invasive methods for the diagnosis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the commonest chronic liver disease and includes simple steatosis and nonalcoholic steatohepatitis (NASH). Since NASH progresses to cirrhosis more frequently and increases liver-related and cardiovascular disease risk substantially more than simple steatosis, there is a great need to differentiate the two entities. Liver biopsy is the gold standard for the diagnosis of NAFLD but its disadvantages, including the risk of complications and sampling bias, stress the need for developing alternative diagnostic methods. Accordingly, several non-invasive markers have been evaluated for the diagnosis of simple steatosis and NASH, including both serological indices and imaging methods. The present review summarizes the current knowledge on the role of these markers in the diagnosis of NAFLD. Current data suggest that ultrasound and the fibrosis-4 score are probably the most appealing methods for detecting steatosis and for distinguishing NASH from simple steatosis, respectively, because of their low cost and relatively high accuracy. However, currently available methods, both serologic and imaging, cannot obviate the need for liver biopsy for diagnosing NASH due to their substantial false positive and false negative rates. Therefore, the current role of these methods is probably limited in patients who are unwilling or have contraindications for undergoing biopsy.

Docosahexaenoic acid and non-alcoholic fatty liver disease in obese children: a novel approach?

Non-alcoholic fatty liver disease represents the most common chronic liver disease in obese children of industrialized countries. Nowadays the first line of treatment of pediatric non-alcoholic fatty liver disease is based on dietary and lifestyle intervention; however compliance to these interventions is very difficult to maintain in long term period. This editorial discusses about docosahexaenoic acid treatment as possible novel approach for non-alcoholic fatty liver disease in obese children. Docosahexaenoic acid may modulate the inflammatory response, improve insulin sensitivity and could be effective in enhancing intestinal barrier integrity, essential to protect a healthy gut-liver axis. Indeed alteration of gut microbiota composition and increased intestinal permeability may rise the exposure of liver to gut-derived bacterial products, causing activation of signalling pathways implicated in liver inflammation and fibrogenesis. This mechanism has been observed in vitro and animal models of non-alcoholic fatty liver disease but also in a clinical study in adults. While evidence suggests that n-3 long-chain polyunsaturated fatty acids supplementation may decrease liver fat in adults, in pediatric population only a study examined this topic. In obese children with non-alcoholic fatty liver disease well designed randomized controlled trials are needed to better clarify the possible efficacy of docosahexaenoic acid treatment, and underlying mechanisms, to identify the optimal required dose and to evaluate if the docosahexaenoic acid effect is limited to the duration of the treatment or it may continue after the end of treatment.

Normal range of hepatic fat fraction on dual- and triple-echo fat quantification MR in children

Objectives

To evaluate hepatic fat fraction on dual- and triple-echo gradient-recalled echo MRI sequences in healthy children.

Materials and Methods

We retrospectively reviewed the records of children in a medical check-up clinic from May 2012 to November 2013. We excluded children with abnormal laboratory findings or those who were overweight. Hepatic fat fraction was measured on dual- and triple-echo sequences using 3T MRI. We compared fat fractions using the Wilcoxon signed rank test and the Bland-Altman 95% limits of agreement. The correlation between fat fractions and clinical and laboratory findings was evaluated using Spearman’s correlation test, and the cut-off values of fat fractions for diagnosing fatty liver were obtained from reference intervals.

Results

In 54 children (M:F = 26:28; 5–15 years; mean 9 years), the dual fat fraction (0.1–8.0%; median 1.6%) was not different from the triple fat fraction (0.4–6.5%; median 2.7%) (p = 0.010). The dual- and triple-echo fat fractions showed good agreement using a Bland-Altman plot (-0.6 ± 2.8%). Eight children (14.8%) on dual-echo sequences and six (11.1%) on triple-echo sequences had greater than 5% fat fraction. From these children, six out of eight children on dual-echo sequences and four out of six children on triple-echo sequences had a 5–6% hepatic fat fraction. When using a cut-off value of a 6% fat fraction derived from a reference interval, only 3.7% of children were diagnosed with fatty liver. There was no significant correlation between clinical and laboratory findings with dual and triple-echo fat fractions.

Conclusions

Dual fat fraction was not different from triple fat fraction. We suggest a cut-off value of a 6% fat fraction is more appropriate for diagnosing fatty liver on both dual- and triple-echo sequences in children.

Self-reported eating speed in relation to non-alcoholic fatty liver disease in adults

PURPOSE

Non-alcoholic fatty liver disease (NAFLD), known to be related to insulin resistance, has been the focus of intensive research efforts due to its increasing prevalence and clinical significance. Rapid eating behavior is another emerging health issue associated with insulin resistance. We aimed to clarify the correlation between self-reported eating speed and NAFLD, both known to be related to insulin resistance.

METHODS

A cross-sectional study was conducted during routine medical checkups on 7,917 consecutively enrolled participants. Anthropometric, biochemical, nutritional, and social parameters were checked. The self-reported eating speed per their usual meal (<5, 5-10, 10-15, and more than 15 min) was recorded by a registered dietitian.

RESULTS

The faster eating groups had a higher proportion of NAFLD, and the grade of NAFLD was advanced. After controlling for anthropometric, cardiometabolic, social, and nutritional parameters, the fastest eating group (<5 min) showed an increased risk of NAFLD compared with the lowest eating speed group (≥15 min) both in total [odds ratio (OR) 1.81, 95% confidence interval (CI) 1.24-2.63] and the participants with BMI < 25 kg/m(2) (OR 1.79, 95% CI 1.22-2.61). As the self-reported eating speed increased, the risk of NAFLD also increased in total and those with BMI < 25 kg/m(2) (P for trend <0.001).

CONCLUSIONS

Fast eating is associated with an increased risk of the presence and grade of NAFLD in Korean adults, especially those with BMI < 25 kg/m(2), since presence of overweight or obesity may be overwhelming the effect on NAFLD.

Republished: Non-alcoholic fatty liver disease: non-invasive investigation and risk stratification

Non-alcoholic fatty liver disease (NAFLD) encompasses a histological spectrum of liver disease, from simple steatosis through to cirrhosis. As the worldwide rates of obesity have increased, NAFLD has become the commonest cause of liver disease in many developed countries, affecting up to a third of the population. The majority of patients have simple steatosis that carries a relatively benign prognosis. However, a significant minority have non-alcoholic steatohepatitis, and have increased liver related and cardiovascular mortality. Identifying those at risk of progressive disease is crucial. Liver biopsy remains the gold standard investigation for assessing stage of disease but its invasive nature makes it impractical for widespread use as a prognostic tool. Non-invasive tools for diagnosis and disease staging are required, reserving liver biopsy for those patients where it offers clinically relevant additional information. This review discusses the non-invasive modalities available for assessing steatosis, steatohepatitis and fibrosis. We propose a pragmatic approach for the assessment of patients with NAFLD to identify those at high risk of progressive disease who require referral to specialist services.

State-of-the-art cross-sectional liver imaging: beyond lesion detection and characterization

Cross-sectional imaging with computed tomography or magnetic resonance imaging is routinely used to detect and diagnose liver lesions; however, these examinations can provide additional important information. The improvement of equipment and techniques has allowed outstanding evaluation of the vascular and biliary anatomy, which is practicable in most routine examinations. Anatomical variants may exclude patients from certain therapeutic options and may be the cause of morbidity or mortality after surgery or interventional procedures. Diffuse liver disease, such as steatosis, hemochromatosis, or fibrosis, must be diagnosed and quantified. Usually these conditions are silent until the late stages, and imaging plays an important role in detecting them early. Additionally, a background of diffuse disease may interfere in a focal lesion systematic reasoning. The diagnostic probability of a particular nodule varies according to the background liver disease. Nowadays, most diffuse liver diseases can be easily and accurately quantified by imaging, which has allowed better understanding of these diseases and improved patient management. Finally, cross-sectional imaging can calculate total and partial liver volumes and estimate the future liver remnant after hepatectomy. This information helps to select patients for portal vein embolization and reduces postoperative complications. Use of a specific hepatic contrast agent on magnetic resonance imaging, in addition to improving detection and characterization of focal lesions, provides functional global and segmental information about the liver parenchyma.

Nonalcoholic fatty liver disease: Noninvasive methods of diagnosing hepatic steatosis

Hepatic steatosis is the buildup of lipids within hepatocytes. It is the simplest stage in nonalcoholic fatty liver disease (NAFLD). It occurs in approximately 30% of the general population and as much as 90% of the obese population in the United States. It may progress to nonalcoholic steatohepatitis, which is a state of hepatocellular inflammation and damage in response to the accumulated fat. Liver biopsy remains the gold standard tool to diagnose and stage NAFLD. However, it comes with the risk of complications ranging from simple pain to life-threatening bleeding. It is also associated with sampling error. For these reasons, a variety of noninvasive radiological markers, including ultrasound, computed tomography, magnetic resonance spectroscopy, and the controlled attenuation parameter using transient elastography and Xenon-133 scan have been proposed to increase our ability to diagnose NAFLD, hence avoiding liver biopsy. The aim of this review is to discuss the utility and accuracy of using available noninvasive diagnostic modalities for fatty liver in NAFLD.

Quantitative MRI for hepatic fat fraction and T2* measurement in pediatric patients with non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in children. The gold standard for diagnosis is liver biopsy. MRI is a non-invasive imaging method to provide quantitative measurement of hepatic fat content. The methodology is particularly appealing for the pediatric population because of its rapidity and radiation-free imaging techniques.

OBJECTIVE

To develop a multi-point Dixon MRI method with multi-interference models (multi-fat-peak modeling and bi-exponential T2* correction) for accurate hepatic fat fraction (FF) and T2* measurements in pediatric patients with NAFLD.

MATERIALS AND METHODS

A phantom study was first performed to validate the accuracy of the MRI fat fraction measurement by comparing it with the chemical fat composition of the ex-vivo pork liver-fat homogenate. The most accurate model determined from the phantom study was used for fat fraction and T2* measurements in 52 children and young adults referred from the pediatric hepatology clinic with suspected or identified NAFLD. Separate T2* values of water (T2*W) and fat (T2*F) components derived from the bi-exponential fitting were evaluated and plotted as a function of fat fraction. In ten patients undergoing liver biopsy, we compared histological analysis of liver fat fraction with MRI fat fraction.

RESULTS

In the phantom study the 6-point Dixon with 5-fat-peak, bi-exponential T2* modeling demonstrated the best precision and accuracy in fat fraction measurements compared with other methods. This model was further calibrated with chemical fat fraction and applied in patients, where similar patterns were observed as in the phantom study that conventional 2-point and 3-point Dixon methods underestimated fat fraction compared to the calibrated 6-point 5-fat-peak bi-exponential model (P < 0.0001). With increasing fat fraction, T2*W (27.9 ± 3.5 ms) decreased, whereas T2*F (20.3 ± 5.5 ms) increased; and T2*W and T2*F became increasingly more similar when fat fraction was higher than 15-20%. Histological fat fraction measurements in ten patients were highly correlated with calibrated MRI fat fraction measurements (Pearson correlation coefficient r = 0.90 with P = 0.0004).

CONCLUSION

Liver MRI using multi-point Dixon with multi-fat-peak and bi-exponential T2* modeling provided accurate fat quantification in children and young adults with non-alcoholic fatty liver disease and may be used to screen at-risk or affected individuals and to monitor disease progress noninvasively.

Non-alcoholic fatty liver disease: what the clinician needs to know

Non-alcoholic fatty liver disease (NAFLD) is the most frequent cause of liver disease in the Western world. Furthermore, it is increasing worldwide, paralleling the obesity pandemic. Though highly frequent, only about one fifth of affected subjects are at risk of developing the progressive form of the disease, non-alcoholic steatohepatitis with fibrosis. Even in the latter, liver disease is slowly progressive, though, since it is so prevalent, it is already the third cause of liver transplantation in the United States, and it is predicted to get to the top of the ranking in few years. Of relevance, fatty liver is also associated with increased overall mortality and particularly increased cardiovascular mortality. The literature and amount of published papers on NAFLD is increasing as fast as its prevalence, which makes it difficult to keep updated in this topic. This review aims to summarize the latest knowledge on NAFLD, in order to help clinicians understanding its pathogenesis and advances on diagnosis and treatment.

Steatosis affects the performance of liver stiffness measurement for fibrosis assessment in patients with genotype 1 chronic hepatitis C

BACKGROUND & AIMS

In Chronic Hepatitis C (CHC), the influence of steatosis on liver stiffness measurement (LSM) is still debated. We assessed the impact of steatosis and its ultrasonographical sign - bright liver echo pattern (BLEP) - on LSM values and on transient elastography (TE) accuracy for the diagnosis of liver fibrosis, in a cohort of consecutive patients with Genotype 1 (G1) CHC.

METHODS

Patients (n=618) were assessed by clinical, ultrasonographic and histological (Scheuer score) features. TE was performed using the M probe.

RESULTS

Male gender (p=0.04), steatosis as continuous variable (p<0.001), severity of necroinflammation (p=0.02) and stage of fibrosis (p<0.001) were associated with LSM by multivariate linear regression analysis. Among patients within the same fibrosis stages (F0-F2 and F3-F4; F0-F3 and F4), mean LSM values, expressed in kPa, were significantly higher in subjects with moderate-severe steatosis (⩾20% at liver biopsy) compared with those without, as well as in patients with BLEP on US compared with their counterpart. In subjects without severe fibrosis (F0-F2) and without cirrhosis (F0-F3), a higher rate of false-positive LSM results was observed in patients with steatosis ⩾20% compared with those without (F0-F2: 35.3% vs. 17.9%; F0-F3: 38.9% vs. 16.6%), and in patients with BLEP on US (F0-F2: 28.0% vs. 18.3%; F0-F3: 29.7% vs. 17.8%) compared with their counterpart.

CONCLUSIONS

In patients with G1 CHC, the presence of moderate-severe steatosis, detected by histology or by US, should always be taken into account in order to avoid overestimations of liver fibrosis assessed by TE.

CEUS and Fibroscan in non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

AIM: To determine intra-hepatic blood flow and liver stiffness in patients with non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) using contrast-enhanced ultrasound and fibroscan.

METHODS: This prospective study included 15 patients with NAFLD, 17 patients with NASH and 16 healthy controls. In each patient, real-time ultrasound was used to locate the portal vein (PV) and the right liver lobe, and 5 mL of SonoVue^® was then injected intravenous in a peripheral vein of the left arm over a 4-s span. Digital recording was performed for 3 min thereafter. The recording was subsequently retrieved to identify an area of interest in the PV area and in the right liver parenchyma (LP) to assess the blood flow by processing the data using dedicated software (Qontrast^®, Bracco, Italy). The following parameters were evaluated: percentage of maximal contrast activity (Peak%), time to peak (TTP, s), regional blood volume (RBV, cm³), regional blood flow (RBF, cm³/s) and mean transit time (MTT, s). At 24-48 h post-injection, liver stiffness was evaluated using Fibroscan and measured in kPa. The statistical evaluation was performed using Student’s t test.

RESULTS: In the PV, the Peak%, RBV and RBF were significantly reduced in the NAFLD and NASH patients compared with the controls (Peak%: NAFLD 26.3 ± 6.6, NASH 28.1 ± 7.3 vs controls 55.8 ± 9.9, P < 0.001; RBV: NAFLD 4202.3 ± 3519.7, NASH 3929.8 ± 1941.3 vs controls 7473 ± 3281, P < 0.01; RBF: NAFLD 32.5 ± 10.8, NASH 32.7 ± 12.1 vs controls 73.1 ± 13.9, P < 0.001). The TTP in the PV was longer in both patient groups but reached statistical significance only in the NASH patients compared with the controls (NASH 79.5 ± 37.8 vs controls 43.2 ± 30, P < 0.01). In the LP, the Peak%, RBV and RBF were significantly reduced in the NAFLD and NASH patients compared with the controls (Peak%: NAFLD 43.2 ± 7.3, NASH 41.7 ± 7.7 vs controls 56.6 ± 6.3, P < 0.001; RBV: NAFLD 4851.5 ± 2009, NASH 5069.4 ± 2292.5 vs controls 6922.9 ± 2461.5, P < 0.05; RBF: NAFLD 55.7 ± 10.1, NASH 54.5 ± 12.1 vs controls 75.9 ± 10.5, P < 0.001). The TTP was longer in both patient groups but did not reach statistical significance. The MTT in both the PV and LP in the NAFLD and NASH patients was not different from that in the controls. Liver stiffness was significantly increased relative to the controls only in the NASH patients (NASH: 6.4 ± 2.2 vs controls 4.6 ± 1.5, P < 0.05).

CONCLUSION: Blood flow derangement within the liver present not only in NASH but also in NAFLD suggests that a vascular flow alteration precedes liver fibrosis development.

Evidence and recommendations for imaging liver fat in children, based on systematic review

BACKGROUND & AIMS

Fatty liver is a common problem in children and increases their risk for cirrhosis, diabetes, and cardiovascular disease. Liver biopsy is the clinical standard for diagnosing and grading fatty liver. However, noninvasive imaging modalities are needed to assess liver fat in children. We performed a systematic review of studies that evaluated imaging liver fat in children.

METHODS

We searched PubMed for original research articles in peer-reviewed journals from January 1, 1982, through December 31, 2012, using the key words "imaging liver fat." Studies included those in English, and those performed in children from birth to 18 years of age. To be eligible for inclusion, studies were required to measure hepatic steatosis via an imaging modality and a quantitative comparator as the reference standard.

RESULTS

We analyzed 9 studies comprising 610 children; 4 studies assessed ultrasonography and 5 studies assessed magnetic resonance imaging (MRI). Ultrasonography was used in the diagnosis of fatty liver with positive predictive values of 47% to 62%. There was not a consistent relationship between ultrasound steatosis score and the reference measurement of hepatic steatosis. Liver fat as measurements by MRI or by spectroscopy varied with the methodologies used. Liver fat measurements by MRI correlated with results from histologic analyses, but sample size did not allow for an assessment of diagnostic accuracy.

CONCLUSIONS

Available evidence does not support the use of ultrasonography for the diagnosis or grading of fatty liver in children. Although MRI is a promising approach, the data are insufficient to make evidence-based recommendations regarding its use in children for the assessment of hepatic steatosis.

Lower fructose intake may help protect against development of nonalcoholic fatty liver in adolescents with obesity

OBJECTIVES

Although obesity is a major risk factor for nonalcoholic fatty liver (NAFL), not all individuals with obesity develop the condition, suggesting that other factors such as diet may also contribute to NAFL development. We evaluated associations between fructose and total sugar intake and subsequent diagnosis of NAFL in adolescents with obesity and without obesity in a population-based cohort.

METHODS

Adolescents participating in the Western Australian Pregnancy Cohort (Raine) Study completed 3-day food records and body mass index measurement at age 14 years. At age 17 years, participants underwent abdominal ultrasound to determine NAFL status. Multivariable logistic regression models were used to analyse associations between energy-adjusted fructose and total sugar intake and NAFL status. Food diaries and liver assessments were completed for 592 adolescents.

RESULTS

The prevalence of NAFL at age 17 was 12.8% for the total group and 50% for adolescents with obesity. Fructose intake did not significantly differ between adolescents with or without NAFL in our cohort as a whole. Among adolescents with obesity, those without NAFL had significantly lower energy-adjusted fructose intake at age 14 years compared with those with NAFL (mean ± standard deviation [SD] 38.8 ± 19.8 g/day, vs 55.7 ± 14.4 g/day, P = 0.02). Energy-adjusted fructose intake was independently associated with NAFL in adolescents with obesity (OR [odds ratio] 1.09, 95% CI 1.01-1.19, P = 0.03) after the adjustment for confounding factors. Energy-adjusted total sugar intake showed less significance (OR 1.03, 95% CI 0.999-1.07, P = 0.06). No significant associations were observed in other body mass index categories.

CONCLUSIONS

Lower fructose consumption in adolescents with obesity at 14 years is associated with a decreased risk of NAFL at 17 years. Fructose rather than overall sugar intake may be more physiologically relevant in this association.

Body mass index and liver stiffness affect accuracy of ultrasonography in detecting steatosis in patients with chronic hepatitis C virus genotype 1 infection

BACKGROUND & AIMS

Few studies have evaluated the accuracy of ultrasonography in detecting steatosis in patients with chronic hepatitis C. We assessed its accuracy in detecting steatosis and factors that affect its diagnostic performance in consecutive patients with chronic hepatitis C virus genotype 1 infection.

METHODS

We analyzed data from 515 patients with chronic hepatitis C, confirmed by liver biopsy, assessing anthropometric, biochemical, metabolic, virologic, and ultrasonography features. Transient elastography was performed to measure liver stiffness. Steatosis was identified with ultrasonography based on detection of a bright liver echo pattern.

RESULTS

Ultrasonography identified steatosis in 5% or more of parenchyma of the liver with 63.6% sensitivity, 90.4% specificity, an 87.5% positive predictive value (PPV), and a 70.3% negative predictive value (NPV). The higher the degree of steatosis (based on histology analysis), the higher the sensitivity values and NPVs (up to values of 75.3% and 93.8%, respectively, for steatosis in ≥30% of liver), and the lower the specificity values and PPVs (down to values of 69.8% and 31.7% for steatosis in ≥30% of liver, respectively). Body mass index of 30 kg/m(2) or greater (odds ratio, 2.761; 95% confidence interval, 1.156-6.595; P = .02) and liver stiffness measurements of 8.9 kPa or higher (odds ratio, 3.128; 95% confidence interval, 1.715-5.706; P < .001) were independent risk factors for false-negative results from ultrasonography when there was 5% or more steatosis, as well as when there was 10% or more, 20% or more, or 30% or more steatosis.

CONCLUSIONS

Ultrasonography detects steatosis with low levels of accuracy in patients with chronic hepatitis C virus genotype 1 infection; it has low NPVs for amounts of steatosis of 5% or more and low PPVs for livers with moderate-severe amounts. Higher body mass indexes and liver stiffness measurements are associated with false-negative results in steatosis detection by ultrasonography.

Non-alcoholic fatty liver disease: a diabetologist's perspective

In the recent years, non-alcoholic fatty liver disease (NAFLD) has emerged as the commonest cause of chronic liver disease in the developed world. The global epidemic of obesity secondary to physical inactivity and adverse food habits accounts for the alarming rise in NAFLD. Metabolic syndrome plays a major role in the pathogenesis of both NAFLD and type 2 diabetes mellitus (T2DM). Whilst most cases of NAFLD remain asymptomatic with only hepatic steatosis, about 30 % progress to non-alcoholic steatohepatitis with chronic liver inflammation that can lead on to fibrosis, cirrhosis, liver failure, and hepatocellular carcinoma. Because of the similar pathogenesis shared between T2DM and NAFLD, T2DM occurs as an important complication in many cases of NAFLD, and many cases of T2DM are further complicated by NAFLD. Rapid progression and increased complications of the individual diseases is the end result of this dual coexistence. Diagnosis of NAFLD relies upon hepatic imaging, serum biochemical markers, and liver biopsy. As in T2DM, the most important management option for patients with NAFLD is lifestyle changes targeted at weight reduction. Other treatment options include insulin sensitizers (metformin and pioglitazone), vitamin E, incretin mimetics, omega-3 fatty acids, cholesterol lowering agents, orlistat, and bariatric surgery. The clinical spectrum, patho-physiological features and therapeutic options of NAFLD share many things in common with T2DM and therefore, this review is to highlight the diabetologist's perspective of the disease.

The prevalence of nonalcoholic fatty liver disease in the Americas

Nonalcoholic fatty liver disease (NAFLD) is an alarming public health problem. The disease is one of the main causes of chronic liver disease worldwide and is directly linked to the increased prevalence of obesity and type 2 diabetes mellitus (T2DM) in the general population. The worldwide prevalence of NAFLD has been estimated at 20-30%, but the prevalence is unknown in the Americas because of a lack of epidemiological studies. However, given the trends in the prevalence of diabetes and obesity, the prevalence of NAFLD and its consequences are expected to increase in the near future. The aim of the present study is to present the current data on the prevalence of NAFLD in the Americas. We performed an electronic search of the main databases from January 2000 to September 2013 and identified 356 reports that were reviewed. We focused on the epidemiology and prevalence of known NAFLD risk factors including obesity, T2DM, and the metabolic syndrome (MS). The prevalence of the MS was highest in the United States, Mexico, Costa Rica, Puerto Rico, Chile, and Venezuela. In addition, Puerto Rico, Guyana, and Mexico have the highest prevalence of T2DM in the Americas, while USA has the most people with T2DM. In conclusion, the prevalence rates of NAFLD and obesity were highest in the United States, Belize, Barbados, and Mexico.

Systematic review with meta-analysis: non-invasive assessment of non-alcoholic fatty liver disease--the role of transient elastography and plasma cytokeratin-18 fragments

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) affects 15-40% of the general population. Some patients have non-alcoholic steatohepatitis (NASH) and progressive fibrosis, and would be candidates for monitoring and treatment.

AIM

To review current literature on the use of non-invasive tests to assess the severity of NAFLD.

METHODS

Systematic literature searching identified studies evaluating non-invasive tests of NASH and fibrosis using liver biopsy as the reference standard. Meta-analysis was performed for areas with adequate number of publications.

RESULTS

Serum tests and physical measurements like transient elastography (TE) have high negative predictive value (NPV) in excluding advanced fibrosis in NAFLD patients. The NAFLD fibrosis score comprises of six routine clinical parameters and has been endorsed by current American guidelines as a screening test to exclude low-risk individuals. The pooled sensitivities and specificities for TE to diagnose F ≥ 2, F ≥ 3 and F4 disease were 79% and 75%, 85% and 85%, and 92% and 92% respectively. Liver stiffness measurement often fails in obese patients, but the success rate can be improved with the use of the XL probe. A number of biomarkers have been developed for the diagnosis of NASH, but few were independently validated. Serum/plasma cytokeratin-18 fragments have been most extensively evaluated and have a pooled sensitivity of 66% and specificity of 82% in diagnosing NASH.

CONCLUSIONS

Current non-invasive tests are accurate in excluding advanced fibrosis in NAFLD patients, and may be used for initial assessment. Further development and evaluation of NASH biomarkers are needed.

Liver steatosis (LS) evaluated through chemical-shift magnetic resonance imaging liver enzymes in morbid obesity; effect of weight loss obtained with intragastric balloon gastric banding

The aim of this study was to evaluate in morbid obesity clinical and metabolic effects related to weight loss on liver steatosis (LS), measured through chemical-shift magnetic resonance imaging (MRI) and liver enzymes. Forty obese subjects (8 M/32 W; BMI 42.8 ± 7.12 kg/m(2), mean ± SD) were evaluated for LS through ultrasound (US-LS), chemical-shift MRI (MRI-LS), liver enzymes [aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyltransferase (GGT), alkaline phosphatase (ALP)], anthropometric parameters [weight, BMI, waist circumference (WC)], lipids, insulin, insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c), oral glucose tolerance test, and body composition [fat mass (FM) and fat-free mass (FFM) at bio-impedance analysis (BIA)]. Anthropometric measures, MRI-LS, BIA, and biochemical parameters were reevaluated 6 months later in 18 subjects undergoing restrictive bariatric approach, i.e., intragastric balloon (BIB, n = 13) or gastric banding (LAGB, n = 5), and in 13 subjects receiving hypocaloric diet. At baseline, US-LS correlates only with MRI-LS, and the latter correlates with ALT, AST, and GGT. After 6 months, subjects undergoing BIB or LAGB had significant changes of BMI, weight, WC, ALT, AST, GGT, ALP, HbA1c, insulin, HOMA-IR, FM, FFM, and MRI-LS. Diet-treated obese subjects had no significant change of any parameter under study; change of BMI, fat mass, and fat-free mass was significantly greater in LAGB/BIB subjects than in diet-treated subjects. Change of MRI-LS showed a significant correlation with changes in weight, BMI, WC, GGT, ALP, and basal MRI-LS. Significant weight loss after BIB or LAGB is associated with decrease in chemical-shift MRI-LS and with reduction in liver enzymes; chemical-shift MRI and liver enzymes allow monitoring of LS in follow-up studies.

Changes of liver fat content and transaminases in obese children after 12-mo nutritional intervention

AIM

To assess a relationship between longitudinal changes in liver fat content and biochemical parameters in obese children after 1-year nutritional intervention.

METHODS

Forty-six obese children, 21 males and 25 females, aged 6-14 years, underwent metabolic measurements, liver ultrasonography (US) and chemical-shift magnetic resonance imaging (MRI) examinations at baseline and after 1-year nutritional intervention. A child was defined obese if her/his body mass index (BMI) was above the age- and sex-adjusted BMI Cole's curve passing through the cut-off of 30 kg/m(2) at 18 years. BMI Z scores were calculated and adjusted for age and gender by using the Cole's LMS-method and Italian reference data. Biochemistry included serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Abdominal US and chemical-shift MRI were performed according to a randomized sequence. The same radiologist performed US by a GE Logiq 9 (General Electric Healthcare Medical Systems, Milwaukee, WI, United States) using a 3.5-MHz convex array transducer. Liver echogenicity was evaluated independently on videotape by 3 radiologists unaware of the child and MRI outcomes, and a consensus was established. Another experienced radiologist, unaware of the child and US data, performed the abdominal chemical-shift MRI with a 1-t system NT-Intera (Philips Medical Systems, Best, The Netherlands) and a phased-array coil. Liver fat fraction (FF) on MRI was judged elevated when greater than 9%. A FF > 18% was considered expressing more severe cases of fatty liver according to Fishbein. A nutritional-behavioral intervention was recommended to promote a normocaloric balanced diet and active lifestyle based on the Italian guidelines for treatment of childhood obesity.

RESULTS

Compared to baseline, at the end of intervention children showed lower intakes of energy (mean ± SD: 2549 ± 1238 Kcal vs 1770 ± 622 Kcal, P < 0.0001), total fat (90 ± 47 g vs 52 ± 23 g, P < 0.0001), carbohydrates (356 ± 174 g vs 241 ± 111 g, P = 0.001), and protein (99 ± 48 g vs 75 ± 23 g, P = 0.006) intakes. Prevalence of FF ≥ 9% declined from 34.8% to 8.7% (P < 0.01), with a mean reduction of 7.8% (95%CI: 5.0-10.6). At baseline, FF was associated with liver biochemical parameters (maximum P < 0.001). At the end of the intervention association was found with AST (P = 0.017). Change of FF was associated with change in AST (P = 0.027) and ALT (P = 0.024). Rate of increased liver echogenicity declined from 45.6% to 21.7% (P < 0.0001). Liver echogenicity was associated with ALT at baseline only (P < 0.001). An age- and sex- adjusted multiple regression analysis showed that FF change was independently associated with change in serum AST (adjusted regression coefficient 0.348, P = 0.048).

CONCLUSION

The results suggest that in obese children longitudinal changes in liver fat content based on MRI may be associated with change in serum transaminases suggesting novelty in monitoring nonalcoholic fatty liver disease.