Nonalcoholic fatty liver disease: rapid evaluation of liver fat content with in-phase and out-of-phase MR imaging

The impact of concomitant metabolic dysfunction-associated fatty liver disease on adverse outcomes in patients with hepatitis B cirrhosis: a propensity score matching study

BACKGROUND AND AIMS

In cirrhotic patients, the clinical relevance of metabolic dysfunction-associated fatty liver disease (MAFLD) is unclear. We aimed to research the relationship between MAFLD and adverse clinical outcomes in patients with hepatitis B cirrhosis.

METHODS

A total of 439 patients with hepatitis B cirrhosis were enrolled. Abdominal MRI and computed tomography were used to calculate liver fat content in order to evaluate steatosis. The Kaplan-Meier method was implemented to generate survival curves. The independent risk factors for prognosis were identified by multiple Cox regression. Propensity score matching (PSM) was used to reduce the influence of confounding factors. This study explored the relevance between MAFLD and mortality, first decompensation and further decompensation.

RESULTS

In our study, most patients were decompensated cirrhosis (n = 332, 75.6%) and the ratio of decompensated cirrhosis patients in non-MAFLD to MAFLD group was 199 : 133. Compared to the non-MAFLD group, patients with MAFLD had worse liver function which mainly reflected that there were more Child-Pugh C patients and higher model for end-stage liver disease score in the MAFLD group. A total of 207 adverse clinical events occurred in the total cohort during a median follow-up of 47 months, including 45 deaths, 28 hepatocellular carcinoma, 23 first decompensation and 111 further decompensation. Cox multivariate analysis showed that MAFLD was an independent risk factor for death [hazard ratio (HR) 1.931; 95% confidence interval (CI) 1.019-3.660; P = 0.044 HR 2.645; 95% CI, 1.145-6.115; P = 0.023] and further decompensation (HR 1.859; 95% CI, 1.261-2.741; P = 0.002 HR 1.953; 95% CI, 1.195-3.192; P = 0.008) before and after PSM. In decompensated group with MAFLD, diabetes had a more significant effect on adverse prognosis than overweight or obesity and other metabolic risk factors.

CONCLUSION

In patients with hepatitis B cirrhosis, concomitant MAFLD can predict a higher risk of further decompensation and death among decompensated individuals. According to patients among MAFLD, diabetes may be a major factor in the occurrence of adverse clinical events.

How to select the quantitative magnetic resonance technique for subjects with fatty liver: A systematic review

BACKGROUND

Early quantitative assessment of liver fat content is essential for patients with fatty liver disease. Mounting evidence has shown that magnetic resonance (MR) technique has high accuracy in the quantitative analysis of fatty liver, and is suitable for monitoring the therapeutic effect on fatty liver. However, many packaging methods and postprocessing functions have puzzled radiologists in clinical applications. Therefore, selecting a quantitative MR imaging technique for patients with fatty liver disease remains challenging.

AIM

To provide information for the proper selection of commonly used quantitative MR techniques to quantify fatty liver.

METHODS

We completed a systematic literature review of quantitative MR techniques for detecting fatty liver, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Studies were retrieved from PubMed, Embase, and Cochrane Library databases, and their quality was assessed using the Quality Assessment of Diagnostic Studies criteria. The Reference Citation Analysis database (https://www.referencecitationanalysis.com) was used to analyze citation of articles which were included in this review.

RESULTS

Forty studies were included for spectroscopy, two-point Dixon imaging, and multiple-point Dixon imaging comparing liver biopsy to other imaging methods. The advantages and disadvantages of each of the three techniques and their clinical diagnostic performances were analyzed.

CONCLUSION

The proton density fat fraction derived from multiple-point Dixon imaging is a noninvasive method for accurate quantitative measurement of hepatic fat content in the diagnosis and monitoring of fatty liver progression.

Non-alcoholic fatty liver disease (NAFLD): a review of pathophysiology, clinical management and effects of weight loss

Given the increasing prevalence of diabetes and obesity worldwide, the deleterious effects of non-alcoholic fatty liver disease (NAFLD) are becoming a growing challenge for public health. NAFLD is the most common chronic liver disease in the Western world. NAFLD is closely associated with metabolic disorders, including central obesity, dyslipidaemia, hypertension, hyperglycaemia and persistent abnormalities of liver function tests.In general NAFLD is a common denominer for a broad spectrum of damage to the liver, which can be due to hepatocyte injury, inflammatory processes and fibrosis. This is normally seen on liver biopsy and can range from milder forms (steatosis) to the more severe forms (non-alcoholic steatohepatitis (NASH), advanced fibrosis, cirrhosis and liver failure). In these patients, advanced fibrosis is the major predictor of morbidity and liver-related mortality, and an accurate diagnosis of NASH and NAFLD is mandatory. Histologic evaluation with liver biopsy remains the gold standard to diagnose NAFLD. Diagnosis of NAFLD is defined as presence of hepatic steatosis, ballooning and lobular inflammation with or without fibrosis. Weight loss, dietary modification, and the treatment of underlying metabolic syndrome remain the mainstays of therapy once the diagnosis is established. Dietary recommendations and lifestyle interventions, weight loss, and the treatment of underlying metabolic syndrome remain the mainstays of therapy once the diagnosis is established with promising results but are difficult to maintain. Pioglitazone and vitamin E are recommended by guidelines in selected patients. This review gives an overview of NAFLD and its treatment options.

Effect of exercise and diet intervention in NAFLD and NASH via GAB2 methylation

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a disorder that extends from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH), which is effectively alleviated by lifestyle intervention. Nevertheless, DNA methylation mechanism underling the effect of environmental factors on NAFLD and NASH is still obscure. The aim of this study was to investigate the effect of exercise and diet intervention in NAFLD and NASH via DNA methylation of GAB2.

METHODS

Methylation of genomic DNA in human NAFLD was quantified using Infinium Methylation EPIC BeadChip assay after exercise (Ex), low carbohydrate diet (LCD) and exercise plus low carbohydrate diet (ELCD) intervention. The output Idat files were processed using ChAMP package. False discovery rate on genome-wide analysis of DNA methylation (q < 0.05), and cytosine-guanine dinucleotides (CpGs) which are located in promoters were used for subsequent analysis (|Δβ|≥ 0.1). K-means clustering was used to cluster differentially methylated genes according to 3D genome information from Human embryonic stem cell. To quantify DNA methylation and mRNA expression of GRB2 associated binding protein 2 (GAB2) in NASH mice after Ex, low fat diet (LFD) and exercise plus low fat diet (ELFD), MassARRAY EpiTYPER and quantitative reverse transcription polymerase chain reaction were used.

RESULTS

Both LCD and ELCD intervention on human NAFLD can induce same DNA methylation alterations at critical genes in blood, e.g., GAB2, which was also validated in liver and adipose of NASH mice after LFD and ELFD intervention. Moreover, methylation of CpG units (i.e., CpG_10.11.12) inversely correlated with mRNA expression GAB2 in adipose tissue of NASH mice after ELFD intervention.

CONCLUSIONS

We highlighted the susceptibility of DNA methylation in GAB2 to ELFD intervention, through which exercise and diet can protect against the progression of NAFLD and NASH on the genome level, and demonstrated that the DNA methylation variation in blood could mirror epigenetic signatures in target tissues of important biological function, i.e., liver and adipose tissue. Trial registration International Standard Randomized Controlled Trial Number Register (ISRCTN 42622771).

Advanced Molecular Imaging (MRI/MRS/1H NMR) for Metabolic Information in Young Adults with Health Risk Obesity

BACKGROUND

Obesity or being overweight is a medical condition of abnormal body fat accumulation which is associated with a higher risk of developing metabolic syndrome. The distinct body fat depots on specific parts of the anatomy have unique metabolic properties and different types of regional excessive fat distribution can be a disease hazard. The aim of this study was to identify the metabolome and molecular imaging phenotypes among a young adult population.

METHODS

The amount and distribution of fat and lipid metabolites profile in the abdomen, liver, and calf muscles of 46 normal weight, 17 overweight, and 13 obese participants were acquired using MRI and MR spectroscopy (MRS), respectively. The serum metabolic profile was obtained using proton NMR spectroscopy. NMR spectra were integrated into seven integration regions, which reflect relative metabolites.

RESULTS

A significant metabolic disorder symptom appeared in the overweight and obese group, and increased lipid deposition occurred in the abdomen, hepatocytes, and muscles that were statistically significant. Overall, the visceral fat depots had a marked influence on dyslipidemia biomarkers, blood triglyceride (r = 0.592, p < 0.001), and high-density lipoprotein cholesterol (r = -0.484, p < 0.001). Intrahepatocellular lipid was associated with diabetes predictors for hemoglobin (HbA1c%; r = 0.379, p < 0.001) and for fasting blood sugar (r = 0.333, p < 0.05). The lipid signals in serum triglyceride and glucose signals gave similar correspondence to biochemical lipid profiles.

CONCLUSIONS

This study proves the association between alteration in metabolome in young adults, which is the key population for early prevention of obesity and metabolic syndrome. This study suggests that dyslipidemia prevalence is influenced mainly by the visceral fat depot, and liver fat depot is a key determinant for glucose metabolism and hyperglycemia. Moreover, noninvasive advanced molecular imaging completely elucidated the impact of fat distribution on the anthropometric and laboratory parameters, especially indices of the metabolic syndrome biomarkers in young adults.

Usefulness of Different Imaging Modalities in Evaluation of Patients with Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are becoming some of the major health problems in well-developed countries, together with the increasing prevalence of obesity, metabolic syndrome, and all of their systemic complications. As the future prognoses are even more disturbing and point toward further increase in population affected with NAFLD/NASH, there is an urgent need for widely available and reliable diagnostic methods. Consensus on a non-invasive, accurate diagnostic modality for the use in ongoing clinical trials is also required, particularly considering a current lack of any registered drug for the treatment of NAFLD/NASH. The aim of this narrative review was to present current information on methods used to assess liver steatosis and fibrosis. There are several imaging modalities for the assessment of hepatic steatosis ranging from simple density analysis by computed tomography or conventional B-mode ultrasound to magnetic resonance spectroscopy (MRS), magnetic resonance imaging proton density fat fraction (MRI-PDFF) or controlled attenuation parameter (CAP). Fibrosis stage can be assessed by magnetic resonance elastography (MRE) or different ultrasound-based techniques: transient elastography (TE), shear-wave elastography (SWE) and acoustic radiation force impulse (ARFI). Although all of these methods have been validated against liver biopsy as the reference standard and provided good accuracy, the MRS and MRI-PDFF currently outperform other methods in terms of diagnosis of steatosis, and MRE in terms of evaluation of fibrosis.

Adherence to a plant-based diet in relation to adipose tissue volumes and liver fat content

BACKGROUND

Better adherence to plant-based diets has been linked to lower risk of metabolic diseases but the effect on abdominal fat distribution and liver fat content is unclear.

OBJECTIVES

We aimed to examine the association between different plant-based diet indices and measures of abdominal fat distribution and liver fat content.

METHODS

In a population-based sample of 578 individuals from Northern Germany (57% male, median age 62 y), diet was assessed with a validated FFQ and an overall, a healthy, and an unhealthy plant-based diet index were derived. Participants underwent MRI to assess volumes of visceral and subcutaneous abdominal adipose tissue and liver signal intensity (LSI), a measure of liver fat content. Fatty liver disease (FLD) was defined as log LSI ≥3.0. Cross-sectional associations of the plant-based diet indices with visceral and subcutaneous abdominal fat volumes, LSI, and FLD were assessed in linear and logistic regression analyses. The most comprehensive model adjusted for age, sex, education, smoking, alcohol, physical activity, energy intake, diabetes, hyperlipidemia, and BMI.

RESULTS

Higher overall and healthy plant-based diet indices both revealed statistically significant associations with lower visceral and subcutaneous abdominal adipose tissue volumes and with lower odds of FLD in multivariable-adjusted models without BMI. Upon additional adjustment for BMI, only the association of the healthy plant-based diet with visceral adipose tissue remained statistically significant (per 10-point higher healthy plant-based diet index, percentage change in visceral adipose tissue: -4.9%, 95% CI: -8.6%, -2.0%). None of the plant-based diet indices was associated with LSI. The unhealthy plant-based diet index was unrelated to any of the abdominal or liver fat parameters.

CONCLUSIONS

Adherence to healthy plant-based diets was associated with lower visceral adipose tissue. None of the other examined associations remained statistically significant after adjustment for BMI.

Accuracy of a Semi-Quantitative Ultrasound Method to Determine Liver Fat Infiltration in Early Adulthood

An inexpensive and simple method to determine non-alcoholic fatty liver disease (NAFLD) is the abdominal ultrasound, but there are still doubts about its accuracy. We assessed the precision of a semi-quantitative ultrasound method to determine liver fat infiltration, using magnetic resonance spectroscopy (MRS) as the reference. The study was conducted in youths from an ongoing cohort study. Clinical validation was performed, using receiver operating characteristic analysis, in n = 60 participants (22.6y; 50% males). Abdominal ultrasound was carried out with liver brightness (score 0-3), diaphragm attenuation (0-2) and liver vessel blurring (0-1) scored by two observers. Liver fat was estimated using MRS. Then, analytical validation was conducted in the remaining participants (n = 555; 22.7y; 51% males) using effects size estimates. An ultrasound score ≥4.0 had the highest sensitivity (78%) and specificity (85%) for NAFLD diagnosis. An area under the curve of 86% denotes a good diagnostic performance of the test, whereas a Kappa of 0.63 suggests substantial agreement of ultrasound vs. MRS. The analytical validation showed that participants having NAFLD according to ultrasound had an unhealthier cardiometabolic profile than participants without the condition. Abdominal ultrasound, combined with a semi-quantitative score system, is a reliable method to determine liver fat infiltration in young adults and should be encouraged whenever MRS is unavailable.

Snacking on whole almonds for 6 weeks improves endothelial function and lowers LDL cholesterol but does not affect liver fat and other cardiometabolic risk factors in healthy adults: the ATTIS study, a randomized controlled trial

BACKGROUND

There is convincing evidence that daily whole almond consumption lowers blood LDL cholesterol concentrations, but effects on other cardiometabolic risk factors such as endothelial function and liver fat are still to be determined.

OBJECTIVES

We aimed to investigate whether isoenergetic substitution of whole almonds for control snacks with the macronutrient profile of average snack intakes, had any impact on markers of cardiometabolic health in adults aged 30-70 y at above-average risk of cardiovascular disease (CVD).

METHODS

The study was a 6-wk randomized controlled, parallel-arm trial. Following a 2-wk run-in period consuming control snacks (mini-muffins), participants consumed either whole roasted almonds (n = 51) or control snacks (n = 56), providing 20% of daily estimated energy requirements. Endothelial function (flow-mediated dilation), liver fat (MRI/magnetic resonance spectroscopy), and secondary outcomes as markers of cardiometabolic disease risk were assessed at baseline and end point.

RESULTS

Almonds, compared with control, increased endothelium-dependent vasodilation (mean difference 4.1%-units of measurement; 95% CI: 2.2, 5.9), but there were no differences in liver fat between groups. Plasma LDL cholesterol concentrations decreased in the almond group relative to control (mean difference -0.25 mmol/L; 95% CI: -0.45, -0.04), but there were no group differences in triglycerides, HDL cholesterol, glucose, insulin, insulin resistance, leptin, adiponectin, resistin, liver function enzymes, fetuin-A, body composition, pancreatic fat, intramyocellular lipids, fecal SCFAs, blood pressure, or 24-h heart rate variability. However, the long-phase heart rate variability parameter, very-low-frequency power, was increased during nighttime following the almond treatment compared with control (mean difference 337 ms2; 95% CI: 12, 661), indicating greater parasympathetic regulation.

CONCLUSIONS

Whole almonds consumed as snacks markedly improve endothelial function, in addition to lowering LDL cholesterol, in adults with above-average risk of CVD.This trial was registered at clinicaltrials.gov as NCT02907684.

Role of Magnetic Resonance Imaging in the Monitoring of Patients with Nonalcoholic Fatty Liver Disease: Comparison with Ultrasonography, Lipid Profile, and Body Mass Index

AIM

The aim of this study was to study the role of magnetic resonance imaging (MRI) in monitoring hepatic fat content in cases of nonalcoholic fatty liver disease (NAFLD).

MATERIALS AND METHODS

41 adults (mean age: 39 years, 22 males; 19 females) with NAFLD were included after obtaining approval from the institutional ethics committee. The baseline clinical (weight, body mass index [BMI]) and biochemical parameters, fatty liver grade on ultrasonography (USG), and hepatic fat signal fraction (FSF) using dual-echo chemical shift imaging and proton density fat fraction on magnetic resonance spectroscopy (MRS-PDFF) were assessed, before and after intervention (dietary and lifestyle changes and oral vitamin E for six months). They were categorized into Group A (good compliance to intervention) and Group B (poor compliance), and the clinical and imaging parameters were compared between them.

RESULTS

After intervention, Group A (n = 30) showed significant reduction in BMI (28.35 ± 3.25 to 27.14 ± 3.24 kg/m²; P < 0.001), hepatic FSF (19.30 ± 9.09% to 11.18 ± 7.61%; P < 0.05), and MRS-PDFF (18.79 ± 8.53% to 10.64 ± 6.66%). In Group B (n = 11), there was significant increase in BMI (28.85 ± 2.41 to 29.31 ± 2.57 kg/m²; P < 0.001), hepatic FSF (18.96 ± 9.79% to 21.48 ± 11.80%; P < 0.05), and reduction in high-density lipoproteins (P < 0.05). Although there was good correlation between USG and MRS in quantifying liver fat (r = 0.84-0.87; P < 0.001), USG was unable to detect <5.3% change in hepatic fat. There was poor correlation between lipid profile and MRS-PDFF. Change in body weight significantly correlated with change in hepatic fat content (r = 0.76; P < 0.001).

CONCLUSION

MRI is useful in accurately quantifying and in monitoring hepatic fat content and is better than clinical and biochemical parameters and USG.

Relationship between Muscle Mass/Strength and Hepatic Fat Content in Post-Menopausal Women

Background and Objectives: Recent studies have shown that low skeletal muscle mass can contribute to non-alcoholic fatty liver disease through insulin resistance. However, the association between muscle mass/strength and hepatic fat content remains unclear in postmenopausal women. Methods: In this study, we assessed the associations between muscle mass/strength and various severities of non-alcoholic fatty liver disease. Using single-voxel proton magnetic resonance spectroscopy, 96 postmenopausal women between the ages of 50 and 65 were divided into four groups (G0–G3) by hepatic fat content: G0 (hepatic fat content <5%, n = 20), G1 (5% ≤ hepatic fat content < 10%, n = 27), G2 (10% ≤ hepatic fat content < 25%, n = 31), and G3 (hepatic fat content ≥25%, n = 18). Muscle mass indexes were estimated as skeletal muscle index (SMI)% (total lean mass/weight × 100) and appendicular skeletal muscular mass index (ASM)% (appendicular lean mass/weight × 100) by dual energy X-ray absorptiometry. Maximal isometric voluntary contraction of the handgrip, elbow flexors, and knee extensors was measured using an adjustable dynamometer chair. Fasting plasma glucose, insulin, and follicle-stimulating hormones were assessed in venous blood samples. Results: The results showed negative correlations between hepatic fat content and SMI% (r = −0.42, p < 0.001), ASM% (r = −0.29, p = 0.005), maximal voluntary force of grip (r = −0.22, p = 0.037), and knee extensors (r = −0.22, p = 0.032). Conclusions: These significant correlations almost remained unchanged even after controlling for insulin resistance. In conclusion, negative correlations exist between muscle mass/strength and the progressed severity of non-alcoholic fatty liver disease among post-menopausal women, and the correlations are independent of insulin resistance.

Alcoholic Hepatitis: A Review

Alcoholic liver disease (ALD) represents a spectrum of injury, ranging from simple steatosis to alcoholic hepatitis to cirrhosis. Regular alcohol use results in fatty changes in the liver which can develop into inflammation, fibrosis and ultimately cirrhosis with continued, excessive drinking. Alcoholic hepatitis (AH) is an acute hepatic inflammation associated with significant morbidity and mortality that can occur in patients with steatosis or underlying cirrhosis. The pathogenesis of ALD is multifactorial and in addition to genetic factors, alcohol-induced hepatocyte damage, reactive oxygen species, gut-derived microbial components result in steatosis and inflammatory cell (macrophage and neutrophil leukocyte) recruitment and activation in the liver. Continued alcohol and pro-inflammatory cytokines induce stellate cell activation and result in progressive fibrosis. Other than cessation of alcohol use, medical therapy of AH is limited to prednisolone in a subset of patients. Given the high mortality of AH and the progressive nature of ALD, there is a major need for new therapeutic intervention for this underserved patient population.

Physical Activity Associates with Muscle Insulin Sensitivity Postbariatric Surgery

PURPOSE

Bariatric surgery is considered as an effective therapeutic strategy for weight loss in severe obesity. Remission of type 2 diabetes is often achieved after the surgery. We investigated whether increase in self-reported habitual physical activity associates with improved skeletal muscle insulin sensitivity and reduction of fat depots after bariatric surgery.

METHODS

We assessed self-reported habitual physical activity using Baecke questionnaire in 18 diabetic and 28 nondiabetic patients with morbid obesity (median age, 46 yr; body mass index, 42.0 kg·m) before and 6 months after bariatric surgery operation. Insulin-stimulated femoral muscle glucose uptake was measured using fluorodeoxyglucose positron emission tomography method during hyperinsulinemia. In addition, abdominal subcutaneous and visceral fat masses were quantified using magnetic resonance imaging and liver fat content using magnetic resonance spectroscopy. Also, serum proinflammatory cytokines were measured.

RESULTS

Patients lost on average 22.9% of weight during the follow-up period of 6 months (P < 0.001). Self-reported habitual physical activity level increased (P = 0.017). Improvement in skeletal muscle insulin sensitivity was observed only in those patients who reported increase in their physical activity postoperatively (P = 0.018). The increase in self-reported physical activity associated with the loss of visceral fat mass (P = 0.029). Postoperative self-reported physical activity correlated also positively with postoperative hepatic insulin clearance (P = 0.02) and tended to correlate negatively with liver fat content (P = 0.076). Postoperative self-reported physical activity also correlated negatively with serum TNFα, methyl-accepting chemotaxis protein and interleukin 6 levels.

CONCLUSIONS

Self-reported physical activity is associated with reversal of skeletal muscle insulin resistance after bariatric surgery as well as with the loss of visceral fat content and improved postoperative metabolism in bariatric surgery patients.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT00793143 (SLEEVEPASS), NCT01373892 (SLEEVEPET2).

Focal hypersteatosis: a pseudolesion in patients with liver steatosis

PURPOSE

We aimed to describe ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) findings of focal hypersteatosis (FHS).

METHODS

We retrospectively reviewed our database for patients with hypersteatosis. Over a 5-year period (February 2005 to September 2010) a total of 17 321 patients underwent abdominal CT scan and 28 patients were determined to have FHS. All patients had US, CT, and MRI studies. Size, area, and density measurements were performed on CT images. Fat signal percentage (FSP) was measured on T1-weighted in- and out-of-phase gradient-echo images. FHS was defined based on MRI findings, as an area of greater signal drop on out-of phase images compared with the rest of the fatty liver.

RESULTS

The period prevelance of focal hypersteatosis was measured as 0.16% over the 5-year period. Cancer was the most common diagnosis (22 of 28 patients, 78.5%), with the breast (32.1%) and colorectal (25%) cancers predominating. FHS was seen in segment 4 (n=26, 92.8%), segment 8 (n=1, 3.6%), and segment 3 (n=1, 3.6%). Shape was nodular in 21 patients (75%), while triangular or amorphous in the remaining 7 patients (25%). FHS was hyperechoic and isoechoic in 5 (17.9%) and 23 (82.1%) patients, respectively. FHS was hypodense on CT of all patients relative to fatty liver. On MRI, the FHS was hyperintense on T1-weighted in-phase images in 17 patients (60.7%). Median liver parenchymal FSP was 21.5% (range, 10%-41.4%) and median FSP of hypersteatotic area was 32.5% (range, 19%-45%).

CONCLUSION

Focal hypersteatosis is a pseudolesion that can be observed in patients with liver steatosis. It appears hypodense on CT and mostly isoechoic on US relative to fatty liver. It may mimic metastasis in cancer patients with steatosis, due to nodular shape and atypical location. MRI should be used for correct diagnosis in patients with equivocal findings on CT to avoid biopsy.

Non-invasive quantification of hepatic fat content in healthy dogs by using proton magnetic resonance spectroscopy and dual gradient echo magnetic resonance imaging

The objective of the present study was to describe two non-invasive methods for fat quantification in normal canine liver by using magnetic resonance imaging (MRI) and spectroscopy. Eleven adult beagle dogs were anesthetized and underwent magnetic resonance examination of the cranial abdomen by performing morphologic, modified Dixon (mDixon) dual gradient echo sequence, and proton magnetic resonance spectroscopy (¹H MRS) imaging. In addition, ultrasonographic liver examination was performed, fine-needle liver aspirates and liver biopsies were obtained, and hepatic triglyceride content was assayed. Ultrasonographic, cytologic, and histologic examination results were unremarkable in all cases. The median hepatic fat fraction calculated was 2.1% (range, 1.3%-5.5%) using mDixon, 0.3% (range, 0.1%-1.0%) using ¹H MRS, and 1.6% (range 1.0%-2.5%) based on triglyceride content. The hepatic fat fractions calculated using mDixon and ¹H MRS imaging were highly correlated to that based on triglyceride content. A weak correlation between mDixon and ¹H MRS imaging was detected. The results show that hepatic fat content can be estimated using non-invasive techniques (mDixon or ¹H MRS) in healthy dogs. Further studies are warranted to evaluate the use of these techniques in dogs with varying hepatic fat content and different hepatic disorders.

Fat accumulates preferentially in the right rather than the left liver lobe in non-diabetic subjects

AIMS

To examine the distribution of liver fat (LFAT) in non-diabetic subjects and test whether the fat in the right as compared to the left lobe correlates better with components of the metabolic syndrome or not.

METHODS

In this cross sectional study, we determined LFAT by ¹H-MRS in the right lobe (LFAT%^MRS), and by MRI (LFAT%^MRI) in four regions of interest (ROIs 1-4, two in the right and two in the left lobe) in 97 non-diabetic subjects (age range 22-74 years, BMI 18-41kg/m²) and compared the accuracy of LFAT^MRI in the different ROIs in diagnosing non-alcoholic fatty liver disease (NAFLD) using areas under the receiver operator characteristic (AUROC) curves.

RESULTS

38% of the subjects had NAFLD (LFAT%^MRS). LFAT%^MRI was significantly higher in the right (5.7±0.5%) than the left (5.1±0.4%) lobe (p<0.02). The AUROC for LFAT%^MRI in the right lobe for diagnosing NAFLD was significantly better than that in the left lobe. The relationships between several metabolic parameters and LFAT%^MRI in the left lobe were significantly worse than those for LFAT%^MRS while there was no difference between LFAT%^MRS and right lobe ROIs.

CONCLUSIONS

Liver right lobe contains more fat and correlates better with components of the metabolic syndrome than the left in non-diabetic subjects.

Noninvasive Quantification of Liver Fat Content by Different Gradient Echo Magnetic Resonance Imaging Sequences in Patients with Nonalcoholic Fatty Liver Disease

Background

Noninvasive quantification of liver fat by gradient echo (GRE) technique is an interesting issue in quantitative magnetic resonance imaging. In this study, the fat content in patients with nonalcoholic fatty liver disease (NAFLD) was quantified with GRE sequences with different T ₁ and T ₂* weighting.

Methods

This prospective, cross-sectional study was performed on thirty NAFLD patients. Sixteen GRE sequences with different T ₁ weighting were performed with four echo times. In each sequence, repetition time (TR) or flip angle was changed and other parameters were fixed. Forty-eight fat indexes (FIs) from 16 sequences were calculated based on three methods. To determine the relationship between FIs and histological findings, Pearson's correlation coefficient was used at the level of 1% significance.

Results

Mean FIs which obtained from Eq. 3 have the maximum values in comparison to other FIs. The maximum FI was 23.58%, which related to heavily T ₁ weighted sequence obtained with method 3. The minimum FI was -2.49%, which related to the minimal T ₁ weighted obtained with method 2. FIs increase with a flip angle, especially at low flip angles. Increase the TR parameter decrease the FIs gradually. Calculated FIs with methods 1 and 3 stronger correlated with histological findings relative to calculated FIs with method 2.

Conclusion

For fat quantification, T ₁ relaxation effects probably more critical than T ₂*. Flip angle parameter could be a major factor causing the overestimation of liver fat content. Sequences with low flip angle are more suitable for fat quantification with methods 1 and 3. In fat quantification with GRE techniques, it is possible that the third and fourth echoes are unnecessary.

Effect of aerobic exercise and diet on liver fat in pre-diabetic patients with non-alcoholic-fatty-liver-disease: A randomized controlled trial

The study aimed to assess whether aerobic exercise (AEx) training and a fibre-enriched diet can reduce hepatic fat content (HFC) and increase glycaemic control in pre-diabetic patients with non-alcoholic fatty liver disease (NAFLD). Six-hundred-and-three patients from seven clinics in Yangpu district, Shanghai, China were recruited. Of them 115 individuals aged 50–65-year fulfilled the inclusion criteria (NAFLD with impaired fasting glucose or impaired glucose tolerance) and were randomly assigned into exercise (AEx n = 29), diet (Diet n = 28), exercise plus diet (AED n = 29), or no-intervention (NI n = 29) groups. Progressive supervised AEx training (60–75% VO2max intensity) was given 2-3 times/week in 30–60 min/sessions, and the diet intervention was provided as lunch with 38% carbohydrate and diet fibre of 12 g/day for 8.6-month. HFC was assessed by ¹H MRS. We found that HFC was significantly reduced in the AEx (−24.4%), diet (−23.2%), and AED (−47.9%) groups by contrast to the 20.9% increase in the NI group (p = 0.001 for all) after intervention. However, only AED group significantly decreased HbA_1c (−4.4%, p = 0.01) compared with the NI group (−0.6%). Aerobic exercise training combined with fibre-enriched diet can reduce HFC more effectively than either exercise or increased fibre-intake alone in pre-diabetic patients with NAFLD.

Epidemiology and Risk Factors of Nonalcoholic Fatty Liver Disease Among Patients with Inflammatory Bowel Disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has been increasingly identified in patients with inflammatory bowel disease (IBD). We aimed to determine risk factors of NAFLD in patients with IBD.

METHODS

We examined 3 groups of patients: IBD + NAFLD, IBD only, and NAFLD only. Data on demographics, body mass index, duration of IBD, type of medication use, laboratory data, and metabolic risk factors were collected.

RESULTS

A total of 168 patients between the ages 19 and 82 were evaluated, 56 patients in each group. Patients with IBD + NAFLD were significantly older than IBD only patients 45.0 (±14.1) versus 35.0 (±13), P = 0.007, and their mean body mass index was higher 30.4 (±10.2) versus 25.6 (±6.4); P = 0.002. IBD + NAFLD patients in comparison with IBD only patients had significantly longer duration of IBD (20 [±12.2] versus 10 [±7.7], P = 0.004), had an increased risk of diabetes (16% versus 2%, P = 0.01), and obesity (40% versus 20%, P = 0.02). There were no differences in the mean age or the mean body mass index (32.6 versus 30.4, P = 0.07) between patients with IBD + NAFLD and NAFLD only. More patients were obese in the NAFLD only group compared with the IBD + NAFLD group (59% versus 40%, P = 0.03), had hypertension (55% versus 33%, P = 0.02), hyperlipidemia (53% versus 17.5%, P = 0.0001), and diabetes (40% versus 16%, P = 0.0001).

CONCLUSIONS

IBD patients with NAFLD had longer disease duration of IBD and developed NAFLD with fewer metabolic risk factors than patients with NAFLD only. These findings suggest that there may be other factors that contribute to the development of NAFLD in the IBD population.

Fibrosis Assessment in Nonalcoholic Fatty Liver Disease (NAFLD) in 2016

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of liver pathologies characterized by hepatic steatosis with a history of little to no alcohol consumption or secondary causes of hepatic steatosis. The prevalence of NAFLD is 20-25 % of the general population in the Western countries and is associated with metabolic risk factors such as obesity, diabetes mellitus, and dyslipidemia. The spectrum of disease ranges from simple steatosis to nonalcoholic steatohepatitis, fibrosis, and cirrhosis. Advanced fibrosis is the most significant predictor of mortality in NAFLD. It is crucial to assess for the presence and degree of hepatic fibrosis in order to make therapeutic decisions and predict clinical outcomes. Liver biopsy, the current gold standard to assess the liver fibrosis, has a number of drawbacks such as invasiveness, sampling error, cost, and inter-/intra-observer variability. There are currently available a number of noninvasive tests as an alternative to liver biopsy for fibrosis staging. These noninvasive fibrosis tests are increasingly used to rule out advanced fibrosis and help guide disease management. While these noninvasive tests perform relatively well for ruling out advanced fibrosis, they also have limitations. Understanding the strengths and limitations of liver biopsy and the noninvasive tests is necessary for deciding when to use the appropriate tests in the evaluation of patients with NAFLD.

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.

Insulin resistance is associated with altered amino acid metabolism and adipose tissue dysfunction in normoglycemic women

Insulin resistance is associated adiposity, but the mechanisms are not fully understood. In this study, we aimed to identify early metabolic alterations associated with insulin resistance in normoglycemic women with varying degree of adiposity. One-hundred and ten young and middle-aged women were divided into low and high IR groups based on their median HOMA-IR (0.9 ± 0.4 vs. 2.8 ± 1.2). Body composition was assessed using DXA, skeletal muscle and liver fat by proton magnetic resonance spectroscopy, serum metabolites by nuclear magnetic resonance spectroscopy and adipose tissue and skeletal muscle gene expression by microarrays. High HOMA-IR subjects had higher serum branched-chain amino acid concentrations (BCAA) (p < 0.05 for both). Gene expression analysis of subcutaneous adipose tissue revealed significant down-regulation of genes related to BCAA catabolism and mitochondrial energy metabolism and up-regulation of several inflammation-related pathways in high HOMA-IR subjects (p < 0.05 for all), but no differentially expressed genes in skeletal muscle were found. In conclusion, in normoglycemic women insulin resistance was associated with increased serum BCAA concentrations, down-regulation of mitochondrial energy metabolism and increased expression of inflammation-related genes in the adipose tissue.

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.

Resistance training enhances insulin suppression of endogenous glucose production in elderly women

An altered prenatal environment during maternal obesity predisposes offspring to insulin resistance, obesity, and their consequent comorbidities, type 2 diabetes and cardiovascular disease. Telomere shortening and frailty are additional risk factors for these conditions. The aim of this study was to evaluate the effects of resistance training on hepatic metabolism and ectopic fat accumulation. Thirty-five frail elderly women, whose mothers' body mass index (BMI) was known, participated in a 4-mo resistance training program. Endogenous glucose production (EGP) and hepatic and visceral fat glucose uptake were measured during euglycemic hyperinsulinemia with [(18)F]fluorodeoxyglucose and positron emission tomography. Ectopic fat was measured using magnetic resonance spectroscopy and imaging. We found that the training intervention reduced EGP during insulin stimulation [from 5.4 (interquartile range 3.0, 7.0) to 3.9 (-0.4, 6.1) μmol·kg body wt(-1)·min(-1), P = 0.042] in the whole study group. Importantly, the reduction was higher among those whose EGP was more insulin resistant at baseline (higher than the median) [-5.6 (7.1) vs. 0.1 (5.4) μmol·kg body wt(-1)·min(-1), P = 0.015]. Furthermore, the decrease in EGP was associated with telomere elongation (r = -0.620, P = 0.001). The resistance training intervention did not change either hepatic or visceral fat glucose uptake or the amounts of ectopic fat. Maternal obesity did not influence the studied measures. In conclusion, resistance training improves suppression of EGP in elderly women. The finding of improved insulin sensitivity of EGP with associated telomere lengthening implies that elderly women can reduce their risk for type 2 diabetes and cardiovascular disease with resistance training.

Quantification of fat deposition in bone marrow in the lumbar vertebra by proton MRS and in-phase and out-of-phase MRI for the diagnosis of osteoporosis

The goal for this study was to investigate if proton MRS (1H-MRS) and out-of-phase and in-phase MRI can quantify the fat deposition in bone marrow within the lumbar vertebra that can be used to distinguish well between osteoporosis patients and healthy control subjects. Sixty-eight subjects participated in this study. The diagnostic results from dual-energy x-ray absorptiometry served as the gold standard, which was able to separate the subjects into osteoporosis (38 subjects) and non-osteoporosis group (30 subjects). Then the 68 subjects were further scanned by 1H-MRS and in-phase and out-of-phase MRI and the findings from the imaging methods were also compared and analyzed. It was found that the measured signal intensity ratio (SIR), lipid-water ratio (LWR) and fat fraction (FF) in L2 vertebra from the two imaging methods were able to identify the fat deposition in bone marrow, which could be used to diagnose osteoporosis. Diagnostic accuracy for osteoporosis based on identified SIR, LRW and FF was analyzed by using ROC curves. Our findings suggested that statistically significant differences were identified between osteoporosis patients and healthy subjects. The sensitivity and specificity equal to 78.9% and 75.9% for SIR, 79.2% and 66.7% for LRW, 71.4% and 72.4% for FF, can be achieved when fat deposition-related parameters in bone marrow from the lumbar vertebra are used as classifiers. Our results showed that fat deposition-related parameters including fat content in bone marrow and water content in the lumbar vertebra are clearly different between the osteoporosis and non-osteoporosis group, suggesting that both 1H-MRS and in-phase and out-of-phase MRI can be used for diagnosing osteoporosis and monitoring its progression.

Total liver fat quantification using three-dimensional respiratory self-navigated MRI sequence

PURPOSE

MRI can produce quantitative liver fat fraction (FF) maps noninvasively, which can help to improve diagnoses of fatty liver diseases. However, most sequences acquire several two-dimensional (2D) slices during one or more breath-holds, which may be difficult for patients with limited breath-holding capacity. A whole-liver 3D FF map could also be obtained in a single acquisition by applying a reliable breathing-motion correction method. Several correction techniques are available for 3D imaging, but they use external devices, interrupt acquisition, or jeopardize the spatial resolution. To overcome these issues, a proof-of-concept study introducing a self-navigated 3D three-point Dixon sequence is presented here.

METHODS

A respiratory self-gating strategy acquiring a center k-space profile was integrated into a three-point Dixon sequence. We obtained 3D FF maps from a water-fat emulsions phantom and fifteen volunteers. This sequence was compared with multi-2D breath-hold and 3D free-breathing approaches.

RESULTS

Our 3D three-point Dixon self-navigated sequence could correct for respiratory-motion artifacts and provided more precise FF measurements than breath-hold multi-2D and 3D free-breathing techniques.

CONCLUSION

Our 3D respiratory self-gating fat quantification sequence could correct for respiratory motion artifacts and yield more-precise FF measurements. Magn Reson Med 76:1400-1409, 2016. © 2015 International Society for Magnetic Resonance in Medicine.

Age- and Gender Dependent Liver Fat Content in a Healthy Normal BMI Population as Quantified by Fat-Water Separating DIXON MR Imaging

OBJECTIVES

To establish age- and sex-dependent values of magnetic resonance (MR) liver fat-signal fraction (FSF) in healthy volunteers with normal body-mass index (BMI).

METHODS

2-point mDIXON sequences (repetition time/echo time, 4.2msec/1.2msec, 3.1msec) at 3.0 Tesla MR were acquired in 80 healthy volunteers with normal BMI (18.2 to 25.7 kg/m2) between 20 and 62 years (10 men/10 women per decade). FSF was measured in 5 liver segments (segment II, III, VI, VII, VIII) based on mean signal intensities in regions of interest placed on mDIXON-based water and fat images. Multivariate general linear models were used to test for significant differences between BMI-corrected FSF among age subgroups. Pearson and Spearman correlations between FSF and several body measures were calculated.

RESULTS

Mean FSF (%) ± standard deviations significantly differed between women (3.91 ± 1.10) and men (4.69 ± 1.38) and varied with age for women/men (p-value: 0.002/0.027): 3.05 ± 0.49/3.74 ± 0.60 (age group 20-29), 3.75 ± 0.66/4.99 ± 1.30 (30-39), 4.76 ± 1.16/5.25 ± 1.97 (40-49) and 4.09 ± 1.26/4.79 ± 0.93 (50-62). FSF differences among age subgroups were significant for women only (p = 0.003).

CONCLUSIONS

MR-based liver fat content is higher in men and peaks in the fifth decade for both genders.

Adipose Tissue Dysfunction and Altered Systemic Amino Acid Metabolism Are Associated with Non-Alcoholic Fatty Liver Disease

Background

Fatty liver is a major cause of obesity-related morbidity and mortality. The aim of this study was to identify early metabolic alterations associated with liver fat accumulation in 50- to 55-year-old men (n = 49) and women (n = 52) with and without NAFLD.

Methods

Hepatic fat content was measured using proton magnetic resonance spectroscopy (¹H MRS). Serum samples were analyzed using a nuclear magnetic resonance (NMR) metabolomics platform. Global gene expression profiles of adipose tissues and skeletal muscle were analyzed using Affymetrix microarrays and quantitative PCR. Muscle protein expression was analyzed by Western blot.

Results

Increased branched-chain amino acid (BCAA), aromatic amino acid (AAA) and orosomucoid were associated with liver fat accumulation already in its early stage, independent of sex, obesity or insulin resistance (p<0.05 for all). Significant down-regulation of BCAA catabolism and fatty acid and energy metabolism was observed in the adipose tissue of the NAFLD group (p<0.001for all), whereas no aberrant gene expression in the skeletal muscle was found. Reduced BCAA catabolic activity was inversely associated with serum BCAA and liver fat content (p<0.05 for all).

Conclusions

Liver fat accumulation, already in its early stage, is associated with increased serum branched-chain and aromatic amino acids. The observed associations of decreased BCAA catabolism activity, mitochondrial energy metabolism and serum BCAA concentration with liver fat content suggest that adipose tissue dysfunction may have a key role in the systemic nature of NAFLD pathogenesis.

Magnetic resonance imaging reveals altered distribution of hepatic fat in children with type 1 diabetes compared to controls

INTRODUCTION

Children with type 1 diabetes have been identified as a risk group for non-alcoholic fatty liver disease (NAFLD). The aim was to compare total hepatic fat fraction and fat distribution across Couinaud segments in children with type 1 diabetes and controls and the relation of hepatic fat to plasma and anthropometric parameters.

METHODS

Hepatic fat fraction and fat distribution across Couinaud segments were measured with magnetic resonance imaging (MRI) in 22 children with type 1 diabetes and 32 controls. Blood tests and anthropometric data were collected.

RESULTS

No children had NAFLD. Children with type 1 diabetes had a slightly lower hepatic fat fraction (median 1.3%) than controls (median 1.8%), and their fat had a different segmental distribution. The fat fraction of segment V was the most representative of the liver as a whole. An incidental finding was that diabetes patients treated with multiple daily injections of insulin (MDI) had a fat distribution more similar to controls than patients with continuous subcutaneous insulin infusion (CSII).

CONCLUSIONS

In children with type 1 diabetes, NAFLD may be less common than recent studies have suggested. Children with type 1 diabetes may have a lower fat fraction and a different fat distribution in the liver than controls. Diabetes treatment with MDI or CSII may affect liver fat, but this needs to be confirmed in a larger sample of patients. The heterogeneity of hepatic fat infiltration may affect results when liver biopsy is used for diagnosing fatty liver.

MR Quantification of the Fatty Fraction from T2*-corrected Dixon Fat/Water Separation Volume-interpolated Breathhold Examination (VIBE) in the Assessment of Muscle Atrophy in Rotator Cuff Tears

RATIONALE AND OBJECTIVES

To assess the usefulness of T2*-corrected fat fraction (FF) map from volume-interpolated breathhold examination (VIBE) magnetic resonance (MR) sequence in patients with the rotator cuff pathology.

MATERIALS AND METHODS

The phantom study was performed to validate the FF maps. Eighty-nine shoulder MR arthrographies were analyzed: (1) divided into three groups namely tendinopathy/normal tendons, partial-thickness tears, and full-thickness tears, and (2) occupation ratio (OR) was measured for muscular atrophy. Uncorrected and T2*-corrected FF maps were reconstructed from the VIBE images. The Pearson correlation test was used to correlate the FFs with ORs. The FF and the OR were compared between groups using the Student t test.

RESULTS

T2*-corrected FF maps could provide a higher correlation than uncorrected FF maps. There were significantly negative correlations between the ORs and the FFs (P < .01). In the normal and the partial-thickness tear group, the OR did not show a significant difference, although the FF maps showed a significant difference (P < .01).

CONCLUSIONS

This quantitative assessment of the T2*-corrected FF in the rotator cuff muscles was found to be reliable and correlated well with the ORs. The T2*-corrected FF maps could be used for more sophisticated assessments of the fat even in the partial-thickness tear.

Liver enzyme levels and hepatic iron content in Fatty liver: a noninvasive assessment in general population by T2* mapping

RATIONALE AND OBJECTIVES

Existing evidence suggests potential contribution of iron in pathogenesis of nonalcoholic fatty liver disease (NAFLD). We aimed to investigate whether hepatic iron content correlates with liver enzyme levels in NAFLD using a noninvasive magnetic resonance imaging (MRI) technique.

MATERIALS AND METHODS

Subjects from Golestan Cohort Study were randomly selected. Diagnosis of NAFLD was made by combination of ultrasound and MRI. Subjects with NAFLD were divided into two groups with high (H-NAFLD) and low (L-NAFLD) enzyme level according to 95th percentile of alanine aminotransferase (ALT) value in normal population. Quantitative T2* maps of entire cross-sectional area of liver were calculated on pixel-by-pixel basis using a semiautomated software.

RESULTS

A total of 207 subjects were enrolled. Mean T2* values were significantly lower in NAFLD group than controls (P < .001) indicating higher iron content. Male subjects with H-NAFLD had statistically lower T2* values than those with L-NAFLD in multivariate analysis (odds ratio, 0.74; 95% confidence interval [CI], 0.58-0.95), whereas this was not observed in women. Unlike women, there was significant negative correlation between ALT levels and T2* values in men with H-NAFLD (r = -0.66, P = .01). Every 1-millisecond decrement in T2* value was associated with 6.37 IU/L increase in ALT level (95% CI, 1.8-10.9, P = .01) in men with H-NAFLD.

CONCLUSIONS

Higher hepatic iron in men with H-NAFLD, estimated by T2* mapping, may support the role of iron in possible progression of simple steatosis to nonalcoholic steatohepatitis. Lack of such correlation in women could be attributed to relatively lower iron storage or other mechanisms rather than iron.

The Global Nonalcoholic Fatty Liver Disease Epidemic: What a Radiologist Needs to Know

Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of disorders from a benign steatosis to hepatocellular carcinoma (HCC). Metabolic syndrome, mainly obesity, plays an important role, both as an independent risk factor and in the pathogenesis of NAFLD. With the progressive epidemics of obesity and diabetes mellitus, the prevalence of NAFLD and its associated complications is expected to increase dramatically. Therapeutic strategies for treating NAFLD and metabolic syndrome, particularly obesity, are continuously being refined. Their goal is the prevention of NAFLD by the management of risk factors, prevention of progression of the disease, as well as management of complications, ultimately preventing morbidity and mortality. Optimal management of NAFLD and metabolic syndrome requires a multidisciplinary collaboration between the government as well as the health system including the nutritionist, primary care physician, radiologist, hepatologist, oncologist, and transplant surgeon. An awareness of the clinical presentation, risk factors, pathogenesis, diagnosis, and management is of paramount importance to a radiologist, both from the clinical perspective as well as from the imaging standpoint. With expertise in imaging modalities as well as minimally invasive percutaneous endovascular therapies, radiologists play an essential role in the comprehensive management, which is highlighted in this article, with cases from our practice. We also briefly discuss transarterial embolization of the left gastric artery (LGA), a novel method that promises to have an enormous potential in the minimally invasive management of obesity, with details of a case from our practice.

Association of a lifestyle index with MRI-determined liver fat content in a general population study

BACKGROUND

In prior studies, lifestyle indices were associated with numerous disease end points, but the association with fatty liver disease (FLD), a key correlate of cardiometabolic risk, is unknown. The aim was to investigate associations between a lifestyle index with liver fat content.

METHODS

Liver fat was quantified by MRI as liver signal intensity (LSI) in 354 individuals selected from a population-based cohort from Germany. Exposure to favourable lifestyle factors was quantified using an additive score with each factor modelled as a dichotomous trait. Favourable lifestyle factors were defined as waist circumference below 102 (men) or 88 cm (women), physical activity ≥3.5 h/week, never-smoking and a favourable dietary pattern, which was derived to explain liver fat variation. In a cross-sectional study, multivariable adjusted linear and logistic regression was applied to investigate the association between the lifestyle index (range 0-4, exposure) and LSI (modelled as a continuous trait or dichotomised as a FLD indicator variable, respectively).

RESULTS

Individuals with four favourable lifestyle factors (n=9%) had lower LSI values (ß -0.40; 95% CI -0.61 to -0.19) and a lower OR (0.09; 95% CI 0.03 to 0.30) for FLD compared with individuals with zero favourable lifestyle factors (n=10%).

CONCLUSIONS

A healthy lifestyle pattern was associated with less liver fat. Prospective studies are warranted.

Diagnosis of alcoholic liver disease

Alcohol is a hepatotoxin that is commonly consumed worldwide and is associated with a spectrum of liver injury including simple steatosis or fatty liver, alcoholic hepatitis, fibrosis, and cirrhosis. Alcoholic liver disease (ALD) is a general term used to refer to this spectrum of alcohol-related liver injuries. Excessive or harmful alcohol use is ranked as one of the top five risk factors for death and disability globally and results in 2.5 million deaths and 69.4 million annual disability adjusted life years. All patients who present with clinical features of hepatitis or chronic liver disease or who have elevated serum elevated transaminase levels should be screened for an alcohol use disorder. The diagnosis of ALD can generally be made based on history, clinical and laboratory findings. However, the diagnosis of ALD can be clinically challenging as there is no single diagnostic test that confirms the diagnosis and patients may not be forthcoming about their degree of alcohol consumption. In addition, clinical findings may be absent or minimal in early ALD characterized by hepatic steatosis. Typical laboratory findings in ALD include transaminase levels with aspartate aminotransferase greater than alanine aminotransferase as well as increased mean corpuscular volume, gamma-glutamyltranspeptidase, and IgA to IgG ratio. In unclear cases, the diagnosis can be supported by imaging and liver biopsy. The histological features of ALD can ultimately define the diagnosis according to the typical presence and distribution of hepatic steatosis, inflammation, and Mallory-Denk bodies. Because of the potential reversible nature of ALD with sobriety, regular screening of the general population and early diagnosis are essential.

Gut-adipose tissue axis in hepatic fat accumulation in humans

BACKGROUND & AIMS

Recent evidence suggests that in animals gut microbiota composition (GMC) affects the onset and progression of hepatic fat accumulation. The aim of this study was to investigate in humans whether subjects with high hepatic fat content (HHFC) differ in their GMC from those with low hepatic fat content (LHFC), and whether these differences are associated with body composition, biomarkers and abdominal adipose tissue inflammation.

METHODS

Hepatic fat content (HFC) was measured using proton magnetic resonance spectroscopy ((1)H MRS). Fecal GMC was profiled by 16S rRNA fluorescence in situ hybridization and flow cytometry. Adipose tissue gene expression was analyzed using Affymetrix microarrays and quantitative PCR.

RESULTS

The HHFC group had unfavorable GMC described by lower amount of Faecalibacterium prausnitzii (FPrau) (p<0.05) and relatively higher Enterobacteria than the LHFC group. Metabolically dysbiotic GMC associated with HOMA-IR and triglycerides (p<0.05 for both). Several inflammation-related adipose tissue genes were differentially expressed and correlated with HFC (p<0.05). In addition, the expression of certain genes correlated with GMC dysbiosis, i.e., low FPrau-to-Bacteroides ratio.

CONCLUSIONS

HHFC subjects differ unfavorably in their GMC from LHFC subjects. Adipose tissue inflammation may be an important link between GMC, metabolic disturbances, and hepatic fat accumulation.

Radiologic evaluation of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a frequent cause of chronic liver diseases, ranging from simple steatosis to nonalcoholic steatohepatitis (NASH)-related liver cirrhosis. Although liver biopsy is still the gold standard for the diagnosis of NAFLD, especially for the diagnosis of NASH, imaging methods have been increasingly accepted as noninvasive alternatives to liver biopsy. Ultrasonography is a well-established and cost-effective imaging technique for the diagnosis of hepatic steatosis, especially for screening a large population at risk of NAFLD. Ultrasonography has a reasonable accuracy in detecting moderate-to-severe hepatic steatosis although it is less accurate for detecting mild hepatic steatosis, operator-dependent, and rather qualitative. Computed tomography is not appropriate for general population assessment of hepatic steatosis given its inaccuracy in detecting mild hepatic steatosis and potential radiation hazard. However, computed tomography may be effective in specific clinical situations, such as evaluation of donor candidates for hepatic transplantation. Magnetic resonance spectroscopy and magnetic resonance imaging are now regarded as the most accurate practical methods of measuring liver fat in clinical practice, especially for longitudinal follow-up of patients with NAFLD. Ultrasound elastography and magnetic resonance elastography are increasingly used to evaluate the degree of liver fibrosis in patients with NAFLD and to differentiate NASH from simple steatosis. This article will review current imaging methods used to evaluate hepatic steatosis, including the diagnostic accuracy, limitations, and practical applicability of each method. It will also briefly describe the potential role of elastography techniques in the evaluation of patients with NAFLD.

Vertebral bone marrow glucose uptake is inversely associated with bone marrow fat in diabetic and healthy pigs: [(18)F]FDG-PET and MRI study

OBJECTIVES

Diabetes induces osteoporosis and during osteoporosis, vertebral bone marrow (VBM) adipose tissue amount increases. The association between this adiposity and bone marrow metabolism is unclear. Here, we compared VBM glucose metabolism and fat content in healthy and diabetic pigs, in vivo, using positron emission tomography (PET), in-phase and out-of-phase magnetic resonance imaging and magnetic resonance proton spectroscopy ((1)H MR spectroscopy).

MATERIALS/METHODS

Eleven pigs (n=11) were used. The intervention group had five diabetic and the control group had six healthy pigs. To measure metabolism, PET-imaging with [(18)F]fluoro-deoxy-glucose ([(18)F]FDG) intravenous tracer was used. 1.5-T MRI with (1)H spectroscopy, in-phase and out-of-phase imaging and chemical TAG analysis of the VBM were performed.

RESULTS

We found a significant inverse correlation between VBM glucose uptake (GU) and VBM fat content (R=-0.800, p<0.01) and TAG concentration assay (R=-0.846, p<0.05). There was a trend, although non-significant, of a linear correlation between VBM (1)H MR spectroscopy and TAG concentration (R=0.661) and (1)H MR spectroscopy and in-phase and out-of-phase MR imaging (R=0.635).

CONCLUSIONS

VBM glucose metabolism coupled with VBM fat content may impact diabetic induced osteoporosis.

Quantification of hepatic steatosis: a comparison of the accuracy among multiple magnetic resonance techniques

BACKGROUND AND AIM

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are important diagnostic tools for the non-invasive assessment of hepatic steatosis (HS). This study was conducted to compare different magnetic resonance (MR) techniques and correlate the MR findings with histological and intracellular lipid density findings.

METHODS

In this institutional review board-approved, Health Insurance Portability and Accountability Act-compliant prospective study, 60 patients scheduled for liver resection were included in this study. Fat fraction in the non-tumorous liver parenchyma was estimated using double-echo MRI, triple-echo MRI (TE-MRI), and MRS. HS was defined by the histologic steatosis percentage (HSP), and intrahepatocellular triglyceride density (IHTGD) of the surgical specimen used as the reference standard. Imaging quantification results were evaluated using Pearson's correlation. Lin's concordance coefficient and Bland-Altman 95% limits of agreement were used to evaluate the concordance of IHTGDs estimated by the three MR techniques. The diagnostic performance was compared using receiver operating characteristic curve analysis.

RESULTS

HS assessed by TE-MRI and MRS had a stronger relationship with HS assessed by HSP and IHTGD. The TE-MRI method had the highest concordance correlation coefficients (ρ = 0.881) and percentage (95%, 57/60) within the Bland-Altman 95% limits of agreement. Receiver operating characteristic curve analysis for diagnosing > 5% HSP showed significantly larger area under the curve (0.9783) for TE-MRI than for double-echo MRI (0.8773, P = 0.0121).

CONCLUSIONS

Among the three MR techniques, TE-MRI and MRS may be the preferred techniques for non-invasive assessment of HS.

Effect of bariatric surgery on liver glucose metabolism in morbidly obese diabetic and non-diabetic patients

BACKGROUND & AIMS

Bariatric surgery reduces weight and improves glucose metabolism in obese patients. We investigated the effects of bariatric surgery on hepatic insulin sensitivity.

METHODS

Twenty-three morbidly obese (nine diabetic and fourteen non-diabetic) patients and ten healthy, lean control subjects were studied using positron emission tomography to assess hepatic glucose uptake in the fasting state and during euglycemic hyperinsulinemia. Magnetic resonance spectroscopy was performed to measure liver fat content and magnetic resonance imaging to obtain liver volume. Obese patients were studied before bariatric surgery (either sleeve gastrectomy or Roux-en-Y gastric bypass) and six months after surgery.

RESULTS

Insulin-induced hepatic glucose uptake was increased by 33% in non-diabetic and by 36% in diabetic patients at follow-up compared with baseline, but not totally normalized. The liver fat content was reduced by 76%, liver volume by 26% and endogenous glucose production by 19% in non-diabetic patients. The respective changes in diabetic patients were 73%, 24%, and 25%. Postoperatively, liver fat content and endogenous glucose production were almost normalized to lean controls, but liver volume remained greater than in control subjects.

CONCLUSIONS

This study shows that bariatric surgery leads to a significant improvement in hepatic insulin sensitivity: insulin-stimulated hepatic glucose uptake was improved and endogenous glucose production reduced when measured, six-months, after surgery. These metabolic effects were accompanied by a marked reduction in hepatic volume and fat content. Overall, the gain in hepatic insulin sensitivity in diabetic patients was quite similar to non-diabetic patients for the same weight reduction.

Comparison of vertebral bone marrow fat assessed by 1H MRS and inphase and out-of-phase MRI among family members

Inphase and out-of-phase magnetic resonance imaging is a robust and fast method which can provide similar vertebral bone marrow fat estimation as (1)H proton magnetic resonance spectroscopy, indicating that this technique is a potentially useful tool in both research and clinical practice.

INTRODUCTION

The importance of evaluating bone marrow fat lies in the fact that osteoporosis and obesity, two disorders of body composition, are growing in prevalence. Bone fat mass can be reliably assessed using proton magnetic resonance spectroscopy ((1)H MRS), but this method is technically demanding and needs advanced post-processing unlike inphase and out-of-phase magnetic resonance imaging (MRI), which is a robust and fast method.

METHODS

We compared vertebral bone marrow fat (BMF) content assessed by inphase and out-of-phase MRI and (1)H MRS using a 1.5-T MRI scanner in mothers (n = 34, aged 49.4 years), fathers (n = 31, aged 53.1 years) and their daughters (n = 40, aged 20.3 years) who participated in the CALEX family study. Signal intensity on the inphase and out-of-phase MRI was analyzed from the same location and size of the single-voxel (1)H MRS measurement.

RESULTS

Positive correlations were found between (1)H MRS and inphase and out-of-phase MRI in the axial plane (r = 0.746, p < 0.001) and sagittal plane (r = 0.804, p < 0.001). The mean differences between (1)H MRS and inphase and out-of-phase MRI in the axial and sagittal planes were relatively small, at 4.13 and 2.67 %, and the agreement between techniques was 89.4 and 93.2 %, respectively. Girls had a significantly lower vertebral BMF than mothers and fathers with both methods (for all, p < 0.001).

CONCLUSIONS

We conclude that inphase and out-of-phase MRI can provide similar vertebral BMF estimation as (1)H MRS, indicating that this technique is a potentially useful tool in both research and clinical practice.

Dietary patterns associated with magnetic resonance imaging-determined liver fat content in a general population study

BACKGROUND

The association between diet and fatty liver disease (FLD) has predominantly been analyzed for single nutrients or foods, and findings have been inconsistent.

OBJECTIVE

We aimed to compare associations of hypothesis-driven and exploratory dietary pattern scores with liver fat content.

DESIGN

Liver fat was measured by using magnetic resonance imaging as liver signal intensity (LSI) in a population-based, cross-sectional study that included 354 individuals. We applied partial least-squares regression to derive an exploratory dietary pattern score that explained variation in both the intake of 38 food groups, which were assessed by using a food-frequency questionnaire, and LSI. The hypothesis-driven score was calculated on the basis of published studies. Multivariable linear or logistic regression was used to investigate associations between dietary pattern scores and LSI or FLD.

RESULTS

A higher percentage of LSI variation was explained by the exploratory (12.6%) compared with the hypothesis-driven (2.2%) dietary pattern. Of the 13 most important food groups of the exploratory dietary pattern, intakes of green and black tea, soups, and beer were also individually associated with LSI values. A 1-unit increase in the exploratory dietary pattern score was positively associated with FLD (OR: 1.56; 95% CI: 1.29, 1.88). Furthermore, a 1-unit increase in the hypothesis-driven dietary pattern score, which consisted of alcohol, soft drinks, meat, coffee, and tea, was positively associated with FLD (OR: 1.25; 95% CI: 1.10, 1.43).

CONCLUSION

We defined a hypothesis-driven dietary pattern and derived an exploratory dietary pattern, both of which included alcohol, meat (poultry), and tea, associated with liver fat content independent from confounders, which should be explored in prospective studies.

Effect of aerobic exercise and low carbohydrate diet on pre-diabetic non-alcoholic fatty liver disease in postmenopausal women and middle aged men--the role of gut microbiota composition: study protocol for the AELC randomized controlled trial

Background

Pre-diabetes and non-alcoholic fatty liver disease (NAFLD) are associated with an unhealthy lifestyle and pose extremely high costs to the healthcare system. In this study, we aim to explore whether individualized aerobic exercise (AEx) and low carbohydrate diet (LCh) intervention affect hepatic fat content (HFC) in pre-diabetes via modification of gut microbiota composition and other post-interventional effects.

Methods/design

A 6-month randomized intervention with 6-month follow-up is conducted from January 2013 to December 2015. The target sample size for intervention is 200 postmenopausal women and middle-aged men aged 50–65 year-old with pre-diabetes and NAFLD. The qualified subjects are randomized into 4 groups with 50 subjects in each group: 1 = AEx, 2 = LCh, 3 = AEx + LCh, and 4 = control. In addition, two age-matched reference groups (5 = pre-diabetes without NAFLD (n = 50) and 6 = Healthy without pre-diabetes or NAFLD (n = 50)) are included. The exercise program consists of progressive and variable aerobic exercise (intensity of 60 to 75% of initial fitness level, 3–5 times/week and 30–60 min/time). The diet program includes dietary consultation plus supplementation with a special lunch meal (40% of total energy intake/day) which aims to reduce the amount of carbohydrate consumption (30%). The control and reference groups are advised to maintain their habitual habits during the intervention. The primary outcome measures are HFC, serum metabolomics and gut microbiota composition. The secondary outcome measures include body composition and cytokines. In addition, socio-psychological aspects, social support, physical activity and diet will be performed by means of questionnaire and interview.

Discussion

Specific individualized exercise and diet intervention in this study offers a more efficient approach for liver fat reduction and diabetes prevention via modification of gut microbiota composition. Besides, the study explores the importance of incorporating fitness assessment and exercise in the management of patients with pre-diabetes and fatty liver disorders. If our program is shown to be effective, it will open new strategies to combat these chronic diseases.

Trial registration

Current Controlled Trials: ISRCTN42622771.

MR quantitative biomarkers of non-alcoholic fatty liver disease: technical evolutions and future trends

Non-alcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis as the earliest manifestation and hallmark, and ranges from benign fatty liver to non-alcoholic steatohepatitis (NASH). Liver biopsy (LB) is considered the reference standard for NAFLD diagnosis, grading and characterization, but it is limited by its invasiveness and observer-dependence. Among imaging surrogates for the assessment of hepatic steatosis, MR is the most accurate. (1)H MR spectroscopy (MRS) provides a quantitative biomarker of liver fat content (LFC) called proton density fat fraction (PDFF), but it is time-consuming, not widely available and limited in sample size. Several MR imaging (MRI) techniques, in particular fat suppression and in-opposed phase techniques, have been used to quantify hepatic steatosis, mainly estimating LFC from water and fat signal intensities rather than proton densities. Several technical measures have been introduced to minimize the effect of confounding factors, in particular a low flip angle, a multiecho acquisition and a spectral modeling of fat with multipeak reconstruction to address respectively T1 effect, T2* effect, and the multifrequency interference effects of fat protons, allowing to use MRI to estimate LFC based on PDFF. Tang et al. evaluated MRI-estimated PDFF, obtained by applying the above-mentioned technical improvements, in the assessment of hepatic steatosis, using histopathology as the reference standard. The identification of PDFF thresholds, even though to be further explored and validated in larger and more diverse cohorts, is useful to identify steatosis categories based on MRI-based steatosis percentages. MRI, with the new refined techniques which provide a robust quantitative biomarker of hepatic steatosis (PDFF) evaluated on the whole liver parenchyma, is a promising non-invasive alternative to LB as the gold standard for steatosis diagnosis and quantification.

Liver abnormalities in drug and substance abusers

Drug and substance abuse remains a major medical problem. Alcohol use, abuse and dependence are highly prevalent conditions. Alcohol related liver disease can present as simple steatosis, steatohepatitis, alcoholic hepatitis or liver cirrhosis. Paracetamol hepatotoxicity secondary to accidental or deliberate overdose is another common problem. While the adverse cardiovascular, neurological, renal and psychiatric consequences of various illicit substance abuses are widely studied and publicized, less attention has been directed towards possible hepatotoxic effects. Illicit drug abuse can cause a range of liver abnormalities ranging from asymptomatic derangement of liver function tests to fulminant hepatic failure. This article reviews the epidemiology, risk factors, clinical manifestations, pathogenesis, investigations, management and prognostic factors of alcohol related liver disease and paracetamol hepatotoxicity as well as the current knowledge pertaining to hepatotoxicity of the more commonly used illicit substances including cannabis, amphetamine type stimulants, cocaine, khat chewing and complementary and alternate medicine.

Liver fat volume fraction quantification with fat and water T1 and T 2* estimation and accounting for NMR multiple components in patients with chronic liver disease at 1.5 and 3.0 T

OBJECTIVE

To validate a magnitude-based method for fat volume fraction (FVF) quantification in the liver without any dominant component ambiguity problems and with the aim of transferring this method to any imaging system (clinical fields of 1.5 and 3.0 T).

METHODS

MR imaging was performed at 1.5 and 3.0 T using a multiple-angle multiple-gradient echo sequence. A quantification algorithm correcting for relaxation time effects using a disjointed estimation of T1 and T2* of fat and water and accounting for the NMR spectrum of fat was developed. Validations were performed on fat-water emulsion at 1.5 and 3.0 T and compared with (1)H-MRS. This was followed by a prospective in-vivo comparative study on 28 patients with chronic liver disease and included histology.

RESULTS

Phantom study showed good agreement between MRI and MRS. MR-estimated FVF and histological results correlated strongly and FVF allowed the diagnosis of mild (cutoff = 5.5 %) and moderate steatosis (cutoff = 15.2 %) with a sensitivity/specificity of 100 %.

CONCLUSION

FVF calculation worked independently of the field strength. FVF may be a relevant biomarker for the clinical follow-up of patients (1) with or at risk of NAFLD (2) of steatosis in patients with other chronic liver diseases.

KEY POINTS

• Non-invasive techniques to diagnose non-alcoholic fatty liver diseases (NAFLD) are important. • Liver fat volume fraction quantified using MRI correlates well with histology. • Fat volume fraction could be a relevant marker for NAFLD clinical follow-up. • Disjointed relaxation time estimation could potentially identify factors contributing to NAFLD.