(1)H MRS assessment of hepatic steatosis in overweight children and adolescents: comparison between 3T and open 1T MR-systems. ACTA ACUST UNITED AC. 2013;38:315-319. [PMID: 22736224 DOI: 10.1007/s00261-012-9930-2]

Changes in Indices of Steatosis and Fibrosis in Liver Grafts of Living Donors After Weight Reduction

Background

A short-term weight reduction program for potential living donors was introduced to reduce the extent of hepatic steatosis prior to liver transplantation. We aimed to investigate changes in non-invasive hepatic steatosis and fibrosis indices among those who completed the program.

Methods

Among 1,950 potential living liver donors between January 2011 and May 2019, 160 living donors joined the weight reduction program. The prospectively collected clinical data of these potential liver donors were analyzed retrospectively. Hepatic steatosis and fibrosis scores were determined using the fatty liver index (FLI), hepatic steatosis index (HSI), and NAFLD fibrosis score (NFS) and compared to MR spectroscopy (MRS) fat fraction results before and after weight reduction.

Results

Thirty-nine potential living donors who had undergone MRS both before and after weight reduction were included in the analysis. Their body weight decreased from 78.02 ± 10.89 kg to 72.36 ± 10.38 kg over a mean of 71.74 ± 58.11 days. FLI, HSI, and MRS values decreased significantly from 41.52 ± 19.05 to 24.53 ± 15.93, 39.64 ± 3.74 to 35.06 ± 3.82, and 12.20 ± 4.05 to 6.24 ± 3.36, respectively. No significant decreases in NFS were observed. There was a significant correlation between the extent of HSI change and the extent of MRS change (R2 value = 0.69, P < 0.001), although there was no correlation between MRS and FLI.

Conclusion

The weight reduction program significantly improved non-invasive indices of hepatic steatosis over a short period. HSI may allow for prediction of simple decreases in hepatic steatosis.

Systematic Review and Meta-analysis of Circulating Fetuin-A Levels in Nonalcoholic Fatty Liver Disease

BACKGROUND AND AIMS

Accumulated studies have reported the key role of circulating fetuin-A in the development and progression of nonalcoholic fatty liver disease (NAFLD) but the results have not been consistent. In this study, we performed a systematic review and meta-analysis to explore the relationship between circulating fetuin-A level and the development and classification of NAFLD.

METHODS

The PubMed, EMBASE, and Cochrane Library databases were searched to obtain the potentially relevant studies up to May 2020. Standardized mean differences (SMD) and 95% confidence intervals of circulating fetuin-A levels were extracted and summarized. Sensitivity, subgroup analysis and meta-regression analysis were performed to investigate the potential heterogeneity. Association of circulating fetuin-A level with classification of NAFLD was also reviewed.

RESULTS

A total of 17 studies were included, composed of 1,755 NAFLD patients and 2,010 healthy controls. Meta-analysis results showed that NAFLD patients had higher circulating fetuin-A level (SMD=0.43, 95% confidence interval [CI]: 0.22-0.63, p<0.001) than controls. Subgroup analysis indicated that circulating fetuin-A level was markedly increased in adult NAFLD patients (SMD=0.48, 95% CI: 0.24-0.72, p<0.001) and not in pediatric/adolescent patients compared to controls. Circulating fetuin-A level was markedly increased in ultrasound-proven NAFLD pediatric/adolescent patients (SMD=0.42, 95% CI: 0.12-0.72, p=0.007), other than in the liver biopsy-proven NAFLD pediatric/adolescent patients. Body mass index might be the influencing factor to the heterogeneity in adult patients. Circulating fetuin-A level was not associated with the classification of NAFL vs. nonalcoholic steatohepatitis (NASH). Whether the circulating fetuin-A level was associated with the development of fibrosis remains controversial.

CONCLUSIONS

Circulating fetuin-A level was significantly higher in NAFLD patients and was not associated with the classification of NAFL vs. NASH. Whether the circulating fetuin-A level was associated with the development of fibrosis remains controversial.

Effect of Sodium Glucose Co-Transporter 2 Inhibitors on Liver Fat Mass and Body Composition in Patients with Nonalcoholic Fatty Liver Disease and Type 2 Diabetes Mellitus

BACKGROUND AND OBJECTIVE

Sodium glucose co-transporter 2 inhibitors increase urinary glucose excretion and reduce visceral adiposity and body weight, but their efficacy on patients with nonalcoholic fatty liver disease has not been sufficiently investigated. The aim of this study was to assess the effect of sodium glucose co-transporter 2 inhibitors on liver fat mass and body composition in patients with nonalcoholic fatty liver disease and type 2 diabetes mellitus.

METHODS

We retrospectively analyzed 17 patients with nonalcoholic fatty liver disease and type 2 diabetes who received sodium glucose co-transporter 2 inhibitors between November 2016 and July 2017. Changes in liver fat, subcutaneous and visceral fat, body composition, and liver function-related parameters were assessed after 24 weeks of sodium glucose co-transporter 2 inhibitor treatment and compared to baseline values.

RESULTS

Ten patients received dapagliflozin at 5 mg/day and seven patients received canagliflozin at 100 mg/day for 24 weeks. All patients completed the study without any serious adverse effects and achieved body weight loss and improved glycated hemoglobin levels. Liver fat mass evaluated by proton magnetic resonance spectroscopy was significantly reduced (19.1% vs. 9.2%, p < 0.01), and so were both subcutaneous and visceral fat mass. The body fat/body weight ratio decreased, whereas the skeletal muscle mass/body weight ratio increased. Liver function (aspartate aminotransferase, alanine aminotransferase, and γ-glutamyl transpeptidase) improved significantly.

CONCLUSIONS

Sodium glucose co-transporter 2 inhibitor treatment not only improved glycemic control but also reduced liver fat mass in patients with nonalcoholic fatty liver disease and type 2 diabetes. Body weight loss was primarily attributable to a reduction in fat mass, especially visceral fat. Thus, sodium glucose co-transporter 2 inhibitors could potentially serve as a therapeutic agent for patients with nonalcoholic fatty liver disease and type 2 diabetes.

Patients with Obesity Caused by Melanocortin-4 Receptor Mutations Can Be Treated with a Glucagon-like Peptide-1 Receptor Agonist

Pathogenic mutations in the appetite-regulating melanocortin-4 receptor (MC4R) represent the most common cause of monogenic obesity with limited treatment options. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) cause weight loss by reducing appetite. We assessed the effect of the GLP-1 RA liraglutide 3.0 mg for 16 weeks in 14 obese individuals with pathogenic MC4R mutations (BMI 37.5 ± 6.8) and 28 matched control participants without MC4R mutation (BMI 36.8 ± 4.8). Liraglutide decreased body weight by 6.8 kg ± 1.8 kg in individuals with pathogenic MC4R mutations and by 6.1 kg ± 1.2 kg in control participants. Total body fat, waist circumference, and fasting and postprandial glucose concentrations similarly decreased in both groups. Thus, liraglutide induced an equal, clinically significant weight loss of 6% in both groups, indicating that the appetite-reducing effect of liraglutide is preserved in MC4R causal obesity and that liraglutide acts independently of the MC4R pathway. Thus, liraglutide could be an effective treatment of the most common form of monogenic obesity.

Noninvasive Quantitative Detection Methods of Liver Fat Content in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) ranges from simple steatosis to NAFLD-related liver cirrhosis and is a main cause of chronic liver diseases. Patients with nonalcoholic steatohepatitis and fibrosis are at a great risk of the progression to cirrhosis or hepatocellular carcinoma, both of which are tightly associated with liver-related mortality. Liver biopsy is still the gold standard for the diagnosis of NAFLD, but some defects, such as serious complications, sampling error and variability in histologic evaluation among pathologists, remain problematic. Therefore, noninvasive, repeatable and accurate diagnostic methods are urgently needed. Ultrasonography is a well-established and lower-cost imaging technique for the diagnosis of hepatic steatosis, especially suitable for population census, but limited by its low sensitivity to diagnose mild steatosis and being highly operator-dependent. Computed tomography also lacks the sensitivity to detect mild steatosis and small changes in fat content, and presents a potential radiation hazard. Controlled attenuation parameter based on the FibroScan^® technology is a promising tool for noninvasive semiquantitative assessment of liver fat content, but the accuracy rate depends on the operator's expertise and is affected by age, width of the intercostal space, skin capsular distance and body mass index. Magnetic resonance imaging and magnetic resonance spectroscopy are regarded as the most accurate quantitative methods for measuring liver fat content in clinical practice, especially for longitudinal follow up of NAFLD patients. In this review, we mainly introduce the current imaging methods that are in use for evaluation of liver fat content and we discuss the advantages and disadvantages of each method.

Higher chlorzoxazone clearance in obese children compared with nonobese peers

AIMS

To test the in vivo activity of Cytochrome P450 (CYP) 2E1 in obese children vs. nonobese children, aged 11-18 years. Secondly, whether the activity of CYP2E1 in these patients is associated with NALFD, diabetes or hyperlipidaemia.

METHODS

Seventy children were divided into groups by body mass index (BMI) standard deviation score (SDS). All children received 250 mg oral chlorzoxazone (CLZ) as probe for CYP2E1 activity. Thirteen blood samples and 20-h urine samples were collected per participant.

RESULTS

Obese children had an increased oral clearance and distribution of CLZ, indicating increased CYP2E1 activity, similar to obese adults. The mean AUC_0-∞ value of CLZ was decreased by 46% in obese children compared to nonobese children. The F was was increased twofold in obese children compared to nonobese children, P < 0.0001. Diabetic biomarkers were significantly increased in obese children, while fasting blood glucose and Hba1c levels were nonsignificant between groups. Liver fat content was not associated with CLZ Cl.

CONCLUSION

Oral clearance of CLZ was increased two-fold in obese children vs. nonobese children aged 11-18 years. This indicates an increased CYP2E1 activity of clinical importance, and dose adjustment should be considered for CLZ.

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

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

Imaging Features of Non-Alcoholic Fatty Liver Disease in Children and Adolescents

Non-invasive diagnosis and quantification of liver steatosis is important to overcome limits of liver biopsy, in order to follow up patients during their therapy and to establish a reference standard that can be used in clinical trials and longitudinal studies. Imaging offers several methods in this setting: ultrasound, which is the cheapest technique and easy to perform; magnetic resonance spectroscopy (MRS), which reflects the real content of triglycerides in a specific volume; and proton density fat fraction (PDFF) magnetic resonance, which is a simple method that reflects the distribution of the fat in the whole liver. Other techniques include ultrasound elastography (EUS) and magnetic resonance elastrography (MRE), which can evaluate the progression of non-alcoholic fatty liver disease (NAFLD) into non-alcoholic steato-hepatitis (NASH) and cirrhosis, by quantifying liver fibrosis.

Comparison of magnetic resonance spectroscopy, proton density fat fraction and histological analysis in the quantification of liver steatosis in children and adolescents

AIM

To establish a threshold value for liver fat content between healthy children and those with non-alcoholic fatty liver disease (NAFLD) by using magnetic resonance imaging (MRI), with liver biopsy serving as a reference standard.

METHODS

The study was approved by the local ethics committee, and written informed consent was obtained from all participants and their legal guardians before the study began. Twenty-seven children with NAFLD underwent liver biopsy to assess the presence of nonalcoholic steatohepatitis. The assessment of liver fat fraction was performed using MRI, with a high field magnet and 2D gradient-echo and multiple-echo T1-weighted sequence with low flip angle and single-voxel point-resolved ¹H MR-Spectroscopy (¹H-MRS), corrected for T1 and T2* decays. Receiver operating characteristic curve analysis was used to determine the best cut-off value. Lin coefficient test was used to evaluate the correlation between histology, MRS and MRI-PDFF. A Mann-Whitney U-test and multivariate analysis were performed to analyze the continuous variables.

RESULTS

According to MRS, the threshold value between healthy children and those with NAFLD is 6%; using MRI-PDFF, a cut-off value of 3.5% is suggested. The Lin analysis revealed a good fit between the histology and MRS as well as MRI-PDFF.

CONCLUSION

MRS is an accurate and precise method for detecting NAFLD in children.

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.

Effect of J coupling on 1.3-ppm lipid methylene signal acquired with localised proton MRS at 3 T

The purpose of this work was to investigate the effect of J-coupling interactions on the quantification and T2 determination of 1.3-ppm lipid methylene protons at 3 T. The response of the 1.3-ppm protons of hexanoic, heptanoic, octanoic, linoleic and oleic acid was measured as a function of point-resolved spectroscopy (PRESS) and stimulated echo acquisition mode (STEAM) TE. In addition, a narrow-bandwidth refocusing PRESS sequence designed to rewind J-coupling evolution of the 1.3-ppm protons was applied to the five fatty acids, to corn oil and to tibial bone marrow of six healthy volunteers. Peak areas were plotted as a function of TE, and data were fitted to monoexponentially decaying functions to determine Mo (the extrapolated area for TE = 0 ms) and T2 values. In phantoms, rewinding J-coupling evolution resulted in 198%, 64%, 44%, 20% and 15% higher T2 values for heptanoic, octanoic, linoleic and oleic acid, and corn oil, respectively, compared with those obtained with standard PRESS. The narrow-bandwidth PRESS sequence also resulted in significant changes in Mo , namely -77%, -22%, 28%, 23% and 28% for heptanoic, octanoic, linoleic and oleic acid, and corn oil, respectively. T2 values obtained with STEAM were closer to the values measured with narrow-bandwidth PRESS. On average, in tibial bone marrow (six volunteers) rewinding J-coupling evolution resulted in 21% ± 3% and 9 % ± 1% higher Mo and T2 values, respectively. This work demonstrates that the consequence of neglecting to consider scalar coupling effects on the quantification of 1.3-ppm lipid methylene protons and their T2 values is not negligible. The linoleic and oleic acid T2 results indicate that T2 measures of lipids with standard MRS techniques are dependent on lipid composition.

1H-MRS Measured Ectopic Fat in Liver and Muscle in Danish Lean and Obese Children and Adolescents

Objectives

This cross sectional study aims to investigate the associations between ectopic lipid accumulation in liver and skeletal muscle and biochemical measures, estimates of insulin resistance, anthropometry, and blood pressure in lean and overweight/obese children.

Methods

Fasting plasma glucose, serum lipids, serum insulin, and expressions of insulin resistance, anthropometry, blood pressure, and magnetic resonance spectroscopy of liver and muscle fat were obtained in 327 Danish children and adolescents aged 8–18 years.

Results

In 287 overweight/obese children, the prevalences of hepatic and muscular steatosis were 31% and 68%, respectively, whereas the prevalences in 40 lean children were 3% and 10%, respectively. A multiple regression analysis adjusted for age, sex, body mass index z-score (BMI SDS), and pubertal development showed that the OR of exhibiting dyslipidemia was 4.2 (95%CI: [1.8; 10.2], p = 0.0009) when hepatic steatosis was present. Comparing the simultaneous presence of hepatic and muscular steatosis with no presence of steatosis, the OR of exhibiting dyslipidemia was 5.8 (95%CI: [2.0; 18.6], p = 0.002). No significant associations between muscle fat and dyslipidemia, impaired fasting glucose, or blood pressure were observed.

Liver and muscle fat, adjusted for age, sex, BMI SDS, and pubertal development, associated to BMI SDS and glycosylated hemoglobin, while only liver fat associated to visceral and subcutaneous adipose tissue and intramyocellular lipid associated inversely to high density lipoprotein cholesterol.

Conclusion

Hepatic steatosis is associated with dyslipidemia and liver and muscle fat depositions are linked to obesity-related metabolic dysfunctions, especially glycosylated hemoglobin, in children and adolescents, which suggest an increased cardiovascular disease risk.

3.0T 1H magnetic resonance spectroscopy for assessment of steatosis in patients with chronic hepatitis C

AIM: To investigate the utility of ¹H magnetic resonance spectroscopy (¹H MRS) as a noninvasive test for steatosis in patients infected with hepatitis C virus.

METHODS: Ninety patients with chronic hepatitis C and pathology data underwent 3.0T ¹H MRS, and the results of MRS and pathological analysis were compared.

RESULTS: This group of patients included 26 people with mild fatty liver (28.89%), 16 people with moderate fatty liver (17.78%), 18 people with severe fatty liver (20.0%), and 30 people without fatty liver (33.33%). The water peak was near 4.7 parts per million (ppm), and the lipid peak was near 1.3 ppm. Analysis of variance revealed that differences in the lipid peak, the area under the lipid peak, ratio of the lipid peak to the water peak, and ratio of the area under the lipid peak to the area under the water peak were statistically significant among the groups. Specifically, as the severity of fatty liver increased, the value of each index increased correspondingly. In the pairwise comparisons, the mean lipid peak, area under the lipid peak, ratio of the lipid peak to the water peak, and ratio of the area under the lipid peak to the area under the water peak were significantly different between the no fatty liver and moderate fatty liver groups, whereas no differences were noted between the severe fatty liver group and the mild or moderate fatty liver group. Area under the ROC curve (AUC) of area ratio in lipid and water and ratio in lipid and water in the no fatty liver group to mild fatty liver group, mild fatty liver group to moderate fatty liver group, and moderate fatty liver disease group to severe fatty liver group, were 0.705, 0.900, and 0.975, respectively.

CONCLUSION: ¹H MRS is a noninvasive technique that can be used to provide information on the effect of liver steatosis on hepatic metabolic processes. This study indicates that the ¹H MRS can be used as an indicator of steatosis in patients with chronic hepatitis C.

Quantitative study of liver magnetic resonance spectroscopy quality at 3T using body and phased array coils with physical analysis and clinical evaluation

This study aims to investigate the quality difference of short echo time (TE) breathhold 1H magnetic resonance spectroscopy (MRS) of the liver at 3.0T using the body and phased array coils, respectively. In total, 20 pairs of single-voxel proton spectra of the liver were acquired at 3.0T using the phased array and body coils as receivers. Consecutive stacks of breathhold spectra were acquired using the point resolved spectroscopy (PRESS) technique at a short TE of 30 ms and a repetition time (TR) of 1500 ms. The first spectroscopy sequence was “copied” for the second acquisition to ensure identical voxel positioning. The MRS prescan adjustments of shimming and water suppression, signal-to noise ratio (SNR), and major liver quantitative information were compared between paired spectra. Theoretical calculation of the SNR and homogeneity of the region of interest (ROI, 2 cm×2 cm×2 cm) using different coils loaded with 3D liver electromagnetic model of real human body was implemented in the theoretical analysis. The theoretical analysis showed that, inside the ROI, the SNR of the phase array coil was 2.8387 times larger than that of body coil and the homogeneity of the phase array coil and body coil was 80.10% and 93.86%, respectively. The experimental results showed excellent correlations between the paired data (all r > 0.86). Compared with the body coil group, the phased array group had slightly worse shimming effect and better SNR (all P values < .01). The discrepancy of the line width because of the different coils was approximately 0.8 Hz (0.00625 ppm). No significant differences of the major liver quantitative information of Cho/Lip2 height, Cho/Lip2 area, and lipid content were observed (all P values >0.05). The theoretical analysis and clinical experiment showed that the phased array coil was superior to the body coil with respect to 3.0T breathhold hepatic proton MRS.

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.