Quantification Of Liver Fat Content Research Articles

Test-Retest Reliability of the Assessment of Fatty Liver Disease Using Low-Dose Computed Tomography in Cardiac Patients.

Non-alcoholic fatty liver disease (NAFLD) is a common disorder that is associated with the risk of cardiovascular diseases. Therefore, its prevalence is high in patients with coronary artery disease. In myocardial perfusion imaging (MPI), low-dose computed tomography (CT) scans are used for attenuation correction in separate stress and rest studies. Here, the test–retest reliability of CT-based quantification of NAFLD was evaluated using these two CT scans. The study population consisted of 261 patients (156 men and 105 women, age 66 ± 10 years). Quantification of liver fat content was based on the radiodensity of the liver in Hounsfield units as well as in relation to corresponding values of the spleen. NAFLD was observed in 47 subjects (18%). CT quantification has good test–retest reliability in assessing NAFLD, with concordance correlation coefficient (CCC) ranging from 0.512 to 0.923, intraclass correlation coefficient (ICC) ranging from 0.513 to 0.923, and coefficient of variation ranging from 3.1 to 7.0%. Regarding the liver to spleen ratio, CCC for non-NAFLD patients and NAFLD patients was 0.552 and 0.911, respectively. For non-NAFLD patients ICC was 0.553 and NAFLD patients it was 0.913. The coefficient of variation for non-NAFLD and NAFLD patients was 4.9% and 3.1%, respectively. Our results suggest that low-dose CT is a feasible and well repeatable method but amount of liver fat contributes to repeatability. In NAFLD patients CCC and ICC were high reflecting excellent reliability, whereas in non-NAFLD patients test-retest reliability was moderate. Assessment of liver fat content can be used as additional information in studies where a CT scan has been done for other medical reasons, such as for low-dose attenuation correction CT along with MPI.

Ultrasound Attenuation Estimation in Harmonic Imaging for Robust Fatty Liver Detection

Accurate detection of liver steatosis is important for liver disease management. Ultrasound attenuation coefficient estimation (ACE) has great potential in quantifying liver fat content. The commonly used ACE methods (e.g., spectral shift methods, reference phantom methods) assume linear tissue response to ultrasound and were developed in fundamental imaging. However, fundamental imaging may be vulnerable to reverberation clutters introduced by the body wall. The clutters superimposed on liver echoes may bias the attenuation estimation. Here we propose a new ACE technique, the reference frequency method (RFM), in harmonic imaging to mitigate the reverberation bias. The accuracy of harmonic RFM was validated through a phantom study. In a pilot patient study, harmonic RFM performed more robustly in vivo compared with fundamental RFM, illustrating the potential of ACE in harmonic imaging.

Quantification of liver fat content with ultrasonographic attenuation measurement function: Correlation with unenhanced multidimensional computerized tomography

PurposeTo evaluate the efficacy of attenuation measurement function (ATT), a newly developed quantitative ultrasonography(US) method based on measurement of the attenuation coefficient, using unenhanced computerized tomography(CT) attenuation values as a reference standard, for the detection and measurement of hepatosteatosis. Material and methodsA total of 98 patients were analyzed. The diagnostic ability of ATT was evaluated using receiver operating characteristic (ROC) curve analysis, and the correlation between liver attenuation index (LAI), the liver-to-spleen attenuation ratio (CTL/S), liver attenuation value (CTL), and ATT was determined. ResultsATT is negatively correlated with LAI (r = −0.571, p < 0.001), CTL/S (r = −0.532, p < 0.001), and mean CTL (r = −0.50, p < 0.001). A significant difference was found between ATT values of patients with different grades of hepatosteatosis (p < 0.001). A significant difference was found between ATT values of patients with LAI < −10 and LAI > −10, CTL < 40 and CTL > 40, and CTL/S < 1 and CTL/S > 1 (p < 0.001). An ATT ≥ 0.665 showed a sensitivity of 100% and a specificity of 90% in diagnosing moderate-severe steatosis. The corresponding area under the ROC curve(AUROC) was 0.935. The intraclass correlation coefficient for the interobserver variability of ATT was 0.907 (95% CI, 0.85–0.95). ConclusionIn conclusion, ATT values for evaluation of hepatosteatosis was closely correlated with the degree of hepatosteatosis and liver fat content. It can be used as a noninvasive method in the diagnosis and follow-up.

Metagenome of Gut Microbiota of Children With Nonalcoholic Fatty Liver Disease.

Aim: To investigate the intestinal flora of nonalcoholic fatty liver disease (NAFLD) in Chinese children and adolescents using metagenomic approach.Methods: All participants underwent magnetic resonance spectroscopy (MRS) to quantify liver fat content. Hepatic steatosis was defined as MRS proton density fat fraction (MRS-PDFF) >5%. A total of 58 children and adolescents were enrolled in this study, including 25 obese NAFLD patients, 18 obese non-NAFLD children, and 15 healthy children. Stool samples were collected and analyzed with metagenomics. We used Shannon index to reflect the alpha diversities of gut microbiota. Wilcoxon rank sum test and Kruskal-Wallis test were performed to evaluate alpha diversities between groups. At last, the differences of gut microbiota composition and functional annotations between obese with and without NAFLD and healthy children were assessed by Kruskal-Wallis test.Results: Significant differences in gut microbiota composition and functional annotations among three groups of children and adolescents have been observed. Deep sequencing of gut microbiota revealed high abundance of phylum Proteobacteria (Gammaproteobacteria) in obese NAFLD patients, comparing with the control group. Overall, obese children without NAFLD had less abundant Helicobacter and Helicobacter pylori. Compared to the control group, in obese children with NAFLD, the abundance of Bacteroidetes (Alistipes) were significantly reduced. Faecalibacterium prausnitzii was the only species representing a difference between obese children with and without NAFLD. There were not significant differences in terms of alpha diversity among three groups. Functional annotations demonstrated that several pathways were differentially enriched between groups, including metabolism of other amino acids, replication and repair, folding, sorting, degradation, and glycan biosynthesis and metabolism.Conclusion: Significantly differences are observed in gut microbiota composition and functional annotations between obese children with and without NAFLD in comparison to the healthy children group. The characteristic of gut microbiota in this study may contribute to a further understanding the gut-liver axis of pediatric NAFLD in China.

Accuracy of multi-echo Dixon sequence in quantification of hepatic steatosis in Chinese children and adolescents.

BACKGROUNDNonalcoholic fatty liver disease (NAFLD) is currently the outstanding cause of chronic liver disease in children and adolescents, especially in overweight and obese groups. Liver biopsy is the reference standard to diagnose NAFLD but invasive, thus it is not the best choice in clinical diagnosis and follow-up. Magnetic resonance (MR) is widely used in clinical trials to noninvasively quantify liver fat content in adults and children in foreign countries. While currently, it is rarely used in Chinese children and adolescents. We postulated that quantifying hepatic steatosis by MR could be extended to children and adolescents in China.AIMTo investigate the accuracy of MR imaging (MRI) in quantifying liver fat with MR spectroscopy (MRS) as a reference. A secondary goal was to assess the prevalence of NAFLD in overweight and obese Chinese children and adolescents.METHODSThere were 86 children and adolescents enrolled in this study, including 65 overweight and obese children and 21 healthy children. The participants underwent MRI and MRS. MRI and MRS were performed using multi-echo Dixon and HISTO sequences, respectively, to calculate hepatic proton density fat fraction (PDFF). Hepatic steatosis was diagnosed using MRS-PDFF > 5% as the threshold. Spearman’s analysis was used to evaluate the correlation between MRI and MRS. The agreement between these two methods was assessed by Bland-Altman analysis.RESULTSThe MRI-PDFF in the MRS region of interest and the entire liver was 9.9% ± 10.3% with a range of 0.3%-39.9%, and 10.6% ± 9.4% with a range of 1.9%-38.9%, respectively. The MRS-PDFF was 9.1% ± 10.0%, with a range of 0.5%-37.8%. The incidence of hepatic steatosis detected by MRS-PDFF was 46.5% (40/86) of all participants, all of whom belonged to the overweight and obese group. Spearman’s analysis indicated an excellent correlation between multi-echo Dixon and MRS (r > 0.9, P < 0.01). Bland-Altman analysis also demonstrated a good agreement between these two methods.CONCLUSIONMulti-echo Dixon shows an excellent correlation and agreement with MRS in quantifying liver fat content and could be a potential tool to detect hepatic steatosis in Chinese children and adolescents.

Non-invasive quantification of liver fat content by different Gradient Echo MRI sequences in patients with Non-Alcoholic Fatty Liver Disease (NAFLD)

Introduction: Non-invasive quantification of liver fat by Gradient echo (GRE) Technique is an interesting issue in quantitative MRI. Despite the numerous advantages of this technique, fat measurement maybe biased by confounding and effects. The aim of this study was to evaluate the GRE pulse sequences with different and weighting for liver fat quantification in patients with Non-Alcoholic Fatty Liver Disease (NAFLD). Materials and Methods: This prospective, cross-sectional study was performed on 30 NAFLD-patients. Sixteen GRE protocols with different weighting contrast were performed with Siemens 1.5 Tesla with four Echo Times ( . For each sequence, TR or flip angle was changed and other scan parameters were fixed.To assessment of signal intensity changes, Regions of Interest (ROIs) which placed on images were copied into other images. 48 fat indexes were calculated based on three equations (Equ 1-3). ( ) (1) (2) ( (3); = ln ( Where is the time difference between and .Correlation between biopsy findings and MRI were performed using Pearson coefficient at the significant level of 1%. Results:Mean fat indexes which obtained from equation 3 have the maximum values in comparison to the other fat indexes. The maximum fat index was 23.58% which related to heavily weighted contrast pulse sequence (sequence 4 TR=50msec, α= defined by equation 3. The minimum fat index was -2.49% which correspond to the minimal weighted pulse sequence (sequence 13TR=200msec, α= defined by equation 2.Relationship between calculated fat indexes and flip angle reveals that, these indexes increased with flip angle especially at low angles. Increasing TR parameter decline fat indexes gradually.Correlational analysis between measured fat indexes and biopsy findings indicate that fat indexes calculated by equation 1 and 3 have slightly stronger correlatecpmpared to resulted data from equation 2. Conclusion:In general, the relaxation effects more critical than in fat quantification. Diagnostic accuracy of First dual GRE and Triple GRE techniques are better than Second dual GRE. There was no significant difference between First dual GRE and Triple GRE technique. In fat quantification with GRE techniques maybe the third and fourth echoes are unnecessary. Findings suggest that flip angle could be a major factor, if not the only one, causing the overestimation of measured fat content. Consequently, GRE techniques for fat quantification are more desirable with lower flip angle.

Quantification of Liver Fat Content With Unenhanced MDCT: Phantom and Clinical Correlation With MRI Proton Density Fat Fraction.

The purpose of this study was to evaluate the relation between unenhanced CT liver attenuation values and MRI-derived proton density fat fraction (PDFF) for estimation of liver fat content at CT. A CT-MRI phantom was constructed and imaged containing 12 vials with lipid fractions ranging from 0% to 100%. For the retrospective clinical arm, 221 patients (120 men, 101 women; mean age, 54 years) underwent both unenhanced CT and chemical shift-encoded MRI of the liver between 2007 and 2017. Among these patients, 92 had more than one 120-kV CT scan for comparison. CT attenuation and MRI PDFF were derived with coregistered ROI measurements in the right hepatic lobe. The 120-kV subgroup of CT examinations performed within 1 month of MRI PDFF examinations (n = 72) served as the primary cohort for linear correlation. The effects of different tube voltage settings, time intervals between CT and MRI, and iron overload were assessed. Linear least squares regression analysis was performed. Phantom results showed excellent linear fit between CT attenuation and MRI PDFF (r2 = 0.986). In patients, 120-kV CT performed within 1 month of MRI PDFF exhibited strong linear correlation (r2 = 0.828) that closely matched the phantom data, yielding the following clinical CT-MRI conversion formula: MRI PDFF (%) = -0.58 × CT attenuation (HU) + 38.2. Correlation worsened for CT-to-MRI intervals longer than 1 month (r2 = 0.565), and this specific relationship did not apply as well to non-120-kV settings (r2 = 0.554). For patients with multiple scans, correlation progressively worsened over time. CT-based liver fat content was underestimated in several patients with iron overload. The linear correlation between unenhanced CT attenuation and MRI PDFF allows quantification of liver fat content by means of unenhanced CT in clinical practice. As expected, correlation worsened with increasing CT-MRI time interval, variable tube voltage settings, and iron overload.

Validation of a motion-robust 2D sequential technique for quantification of hepatic proton density fat fraction during free breathing.

Current chemical-shift-encoded (CSE) MRI techniques for measuring hepatic proton density fat fraction (PDFF) are sensitive to motion artifacts. Initial validation of a motion-robust 2D-sequential CSE-MRI technique for quantification of hepatic PDFF. Phantom study and prospective in vivo cohort. Fifty adult patients (27 women, 23 men, mean age 57.2 years). 3D, 2D-interleaved, and 2D-sequential CSE-MRI acquisitions at 1.5T. Three CSE-MRI techniques (3D, 2D-interleaved, 2D-sequential) were performed in a PDFF phantom and in vivo. Reference standards were 3D CSE-MRI PDFF measurements for the phantom study and single-voxel MR spectroscopy hepatic PDFF measurements (MRS-PDFF) in vivo. In vivo hepatic MRI-PDFF measurements were performed during a single breath-hold (BH) and free breathing (FB), and were repeated by a second reader for the FB 2D-sequential sequence to assess interreader variability. Correlation plots to validate the 2D-sequential CSE-MRI against the phantom and in vivo reference standards. Bland-Altman analysis of FB versus BH CSE-MRI acquisitions to evaluate robustness to motion. Bland-Altman analysis to assess interreader variability. Phantom 2D-sequential CSE-MRI PDFF measurements demonstrated excellent agreement and correlation (R2 > 0.99) with 3D CSE-MRI. In vivo, the mean (±SD) hepatic PDFF was 8.8 ± 8.7% (range 0.6-28.5%). Compared with BH acquisitions, FB hepatic PDFF measurements demonstrated bias of +0.15% for 2D-sequential compared with + 0.53% for 3D and +0.94% for 2D-interleaved. 95% limits of agreement (LOA) were narrower for 2D-sequential (±0.99%), compared with 3D (±3.72%) and 2D-interleaved (±3.10%). All CSE-MRI techniques had excellent correlation with MRS (R2 > 0.97). The FB 2D-sequential acquisition demonstrated little interreader variability, with mean bias of +0.07% and 95% LOA of ± 1.53%. This motion-robust 2D-sequential CSE-MRI can accurately measure hepatic PDFF during free breathing in a patient population with a range of PDFF values of 0.6-28.5%, permitting accurate quantification of liver fat content without the need for suspended respiration. 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1578-1585.

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 T1 and T2* weighting.Methods:This prospective, cross-sectional study was performed on thirty NAFLD patients. Sixteen GRE sequences with different T1 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 T1 weighted sequence obtained with method 3. The minimum FI was −2.49%, which related to the minimal T1 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, T1 relaxation effects probably more critical than T2*. 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.

Multimaterial Decomposition Algorithm for the Quantification of Liver Fat Content by Using Fast-Kilovolt-Peak Switching Dual-Energy CT: Clinical Evaluation.

Purpose To assess the clinical accuracy and reproducibility of liver fat quantification with the multimaterial decomposition (MMD) algorithm, comparing the performance of MMD with that of magnetic resonance (MR) spectroscopy by using liver biopsy as the reference standard. Materials and Methods This prospective study was approved by the institutional ethics committee, and patients provided written informed consent. Thirty-three patients suspected of having hepatic steatosis underwent non-contrast material-enhanced and triple-phase dynamic contrast-enhanced dual-energy computed tomography (CT) (80 and 140 kVp) and single-voxel proton MR spectroscopy within 30 days before liver biopsy. Percentage fat volume fraction (FVF) images were generated by using the MMD algorithm on dual-energy CT data to measure hepatic fat content. FVFs determined by using dual-energy CT and percentage fat fractions (FFs) determined by using MR spectroscopy were compared with histologic steatosis grade (0-3, as defined by the nonalcoholic fatty liver disease activity score system) by using Jonckheere-Terpstra trend tests and were compared with each other by using Bland-Altman analysis. Real non-contrast-enhanced FVFs were compared with triple-phase contrast-enhanced FVFs to determine the reproducibility of MMD by using Bland-Altman analyses. Results Both dual-energy CT FVF and MR spectroscopy FF increased with increasing histologic steatosis grade (trend test, P < .001 for each). The Bland-Altman plot of dual-energy CT FVF and MR spectroscopy FF revealed a proportional bias, as indicated by the significant positive slope of the line regressing the difference on the average (P < .001). The 95% limits of agreement for the differences between real non-contrast-enhanced and contrast-enhanced FVFs were not greater than about 2%. Conclusion The MMD algorithm quantifying hepatic fat in dual-energy CT images is accurate and reproducible across imaging phases. © RSNA, 2017 Online supplemental material is available for this article.

Multimaterial Decomposition Algorithm for the Quantification of Liver Fat Content by Using Fast-Kilovolt-Peak Switching Dual-Energy CT: Experimental Validation.

Purpose To assess the ability of fast-kilovolt-peak switching dual-energy computed tomography (CT) by using the multimaterial decomposition (MMD) algorithm to quantify liver fat. Materials and Methods Fifteen syringes that contained various proportions of swine liver obtained from an abattoir, lard in food products, and iron (saccharated ferric oxide) were prepared. Approval of this study by the animal care and use committee was not required. Solid cylindrical phantoms that consisted of a polyurethane epoxy resin 20 and 30 cm in diameter that held the syringes were scanned with dual- and single-energy 64-section multidetector CT. CT attenuation on single-energy CT images (in Hounsfield units) and MMD-derived fat volume fraction (FVF; dual-energy CT FVF) were obtained for each syringe, as were magnetic resonance (MR) spectroscopy measurements by using a 1.5-T imager (fat fraction [FF] of MR spectroscopy). Reference values of FVF (FVFref) were determined by using the Soxhlet method. Iron concentrations were determined by inductively coupled plasma optical emission spectroscopy and divided into three ranges (0 mg per 100 g, 48.1-55.9 mg per 100 g, and 92.6-103.0 mg per 100 g). Statistical analysis included Spearman rank correlation and analysis of covariance. Results Both dual-energy CT FVF (ρ = 0.97; P < .001) and CT attenuation on single-energy CT images (ρ = -0.97; P < .001) correlated significantly with FVFref for phantoms without iron. Phantom size had a significant effect on dual-energy CT FVF after controlling for FVFref (P < .001). The regression slopes for CT attenuation on single-energy CT images in 20- and 30-cm-diameter phantoms differed significantly (P = .015). In sections with higher iron concentrations, the linear coefficients of dual-energy CT FVF decreased and those of MR spectroscopy FF increased (P < .001). Conclusion Dual-energy CT FVF allows for direct quantification of fat content in units of volume percent. Dual-energy CT FVF was larger in 30-cm than in 20-cm phantoms, though the effect of object size on fat estimation was less than that of CT attenuation on single-energy CT images. In the presence of iron, dual-energy CT FVF led to underestimateion of FVFref to a lesser degree than FF of MR spectroscopy led to overestimation of FVFref. © RSNA, 2016 Online supplemental material is available for this article.

FRI-325 - Quantification of Liver Fat Content: Diagnostic Evaluation of Proton Magnetic Resonance Spectroscopy Compared with Histological Methods

FRI-325 - Quantification of Liver Fat Content: Diagnostic Evaluation of Proton Magnetic Resonance Spectroscopy Compared with Histological Methods

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.

Covering the Cover

Covering the Cover

Techniques for quantification of liver fat in risk stratification of diabetics

Fatty liver disease plays an important role in the development of type 2 diabetes. Accurate techniques for detection and quantification of liver fat are essential for clinical diagnostics. Chemical shift-encoded magnetic resonance imaging (MRI) is a simple approach to quantify liver fat content. Liver fat quantification using chemical shift-encoded MRI is influenced by several bias factors, such as T2* decay, T1 recovery and the multispectral complexity of fat. The confounder corrected proton density fat fraction is a simple approach to quantify liver fat with comparable results independent of the software and hardware used. The proton density fat fraction is an accurate biomarker for assessment of liver fat. An accurate and reproducible quantification of liver fat using chemical shift-encoded MRI requires a calculation of the proton density fat fraction.

Ultrasound hepatic/renal ratio and hepatic attenuation rate for quantifying liver fat content.

To establish and validate a simple quantitative assessment method for nonalcoholic fatty liver disease (NAFLD) based on a combination of the ultrasound hepatic/renal ratio and hepatic attenuation rate. A total of 170 subjects were enrolled in this study. All subjects were examined by ultrasound and (1)H-magnetic resonance spectroscopy ((1)H-MRS) on the same day. The ultrasound hepatic/renal echo-intensity ratio and ultrasound hepatic echo-intensity attenuation rate were obtained from ordinary ultrasound images using the MATLAB program. Correlation analysis revealed that the ultrasound hepatic/renal ratio and hepatic echo-intensity attenuation rate were significantly correlated with (1)H-MRS liver fat content (ultrasound hepatic/renal ratio: r = 0.952, P = 0.000; hepatic echo-intensity attenuation r = 0.850, P = 0.000). The equation for predicting liver fat content by ultrasound (quantitative ultrasound model) is: liver fat content (%) = 61.519 × ultrasound hepatic/renal ratio + 167.701 × hepatic echo-intensity attenuation rate -26.736. Spearman correlation analysis revealed that the liver fat content ratio of the quantitative ultrasound model was positively correlated with serum alanine aminotransferase, aspartate aminotransferase, and triglyceride, but negatively correlated with high density lipoprotein cholesterol. Receiver operating characteristic curve analysis revealed that the optimal point for diagnosing fatty liver was 9.15% in the quantitative ultrasound model. Furthermore, in the quantitative ultrasound model, fatty liver diagnostic sensitivity and specificity were 94.7% and 100.0%, respectively, showing that the quantitative ultrasound model was better than conventional ultrasound methods or the combined ultrasound hepatic/renal ratio and hepatic echo-intensity attenuation rate. If the (1)H-MRS liver fat content had a value < 15%, the sensitivity and specificity of the ultrasound quantitative model would be 81.4% and 100%, which still shows that using the model is better than the other methods. The quantitative ultrasound model is a simple, low-cost, and sensitive tool that can accurately assess hepatic fat content in clinical practice. It provides an easy and effective parameter for the early diagnosis of mild hepatic steatosis and evaluation of the efficacy of NAFLD treatment.

Noninvasive Quantification of Hepatic Steatosis: Relationship Between Obesity Status and Liver Fat Content

The aim of this study was to assess and compare fat content within the liver for normal (body mass index (BMI) &lt; 25 kg/m2), overweight (25-30 kg/m2) and obese (≥ 30 kg/m2) subjects using a noninvasive, non-contrast computed tomography (CT) quantification method. Adult subjects aged 18-60 yrs scheduled to undergo CT examination of the abdominal region were recruited for this study, stratified across BMI categories. Liver volume, fat content, and lean liver volume were determined using CT methods. A total of 100 subjects were recruited, including 30 normal weight, 31 overweight, and 39 obese. Total liver volume increased with BMI, with mean values of 1138 ± 277, 1374 ± 331, and 1766 ± 389 cm3 for the normal, overweight, and obese, respectively (P &lt; 0.001), which was due to an increase in both liver fat content and lean liver volume with BMI. Some obese subjects had no or minimal hepatic fat content. The prevalence of mild fatty liver in this study of 100 subjects was overestimated for all BMI categories using a range of qualitative diagnostic measures, with predicted prevalence of fatty liver in obese subjects ranging from 76.9% for liver-to-spleen ratio ≤ 1.1 to 89.7% for liver attenuation index (liver HU - spleen HU) ≤ 40, compared to 66.7% by quantification of fat content. Results show that total liver volume increases with BMI, however, not all obese subjects display fatty infiltration of the liver. CT quantification of liver fat content may be suitable for accurate diagnosis of hepatic steatosis in clinical practice and assessment of donor livers for transplantation.

Assessment of hepatic fatty infiltration using dual-energy computed tomography: a phantom study

The purpose of this study was to examine the performance of dual-energy computed tomography (DECT) for the quantification of liver fat content (LFC). We prepared two phantoms: homogenized mixtures of porcine liver and fat and homogeneous mixtures of liver- and fat-equivalent solutions. Tubes containing mixtures with known fat concentrations were scanned on a dual-source CT scanner using two DE scanning protocols (80 kV/Sn140 kV and 100 kV/Sn140 kV). Attenuation curves obtained from DECT were used to describe attenuations of various degrees of LFC at different energies. LFC was calculated from DECT data and compared with the known LFC. The phantom made of liver/fat mixtures was not used for liver fat quantification because the increase of fat content did not show a decline of CT numbers. This may be due to inhomogeneity as observed in CT images. Attenuation curves obtained from two DE scanning protocols had the ability to discriminate small differences in fat concentrations. Our results also showed a strong correlation between DECT measurements and known LFC (R2 > 0.99, P < 0.005). DECT will be a reliable tool for liver fat quantification. Furthermore, attenuation curves obtained from DECT data can be used for discriminating various degrees of LFC.

Tu1052 Prognostic Value of Contrast-Enhanced Ultrasonography in Patients With Small Hepatocellular Carcinoma

Introduction: Epidemiological studies have shown that nonalcoholic fatty liver disease (NAFLD) not only is a possible precursor of cirrhosis, but also has been associated with metabolic syndrome, diabetes and cardiovascular disease. There is a need to find a biomarker which proves to be reliable, non-invasive, and easy to perform in clinical practice. Our aim was to know whether serum alanine aminotransferase (ALT) value is a reliable biomarker of liver fat content in subjects with NAFLD in the general population, and to determine if the current threshold of normality for ALT is appropriate to assess the presence of liver fat in these subjects. Methods: This is a cross-sectional, randomized, prospective, populationbased study. We studied 120 healthy subjects attending health screening centers, alcohol consumption less than 50 g/week. Subjects underwent blood tests including aminotransferases. Viral hepatitis, autoimmune, drugs and others causes of liver disease were excluded. Measurements: quantification of liver fat content by spectroscopy 1H MR with magnetic field strength of 3 tesla. We used a cut off value .5% of liver fat content as the upper limit of normal for the diagnosis of hepatic steatosis (1). Serum ALT levels by commercially available kits. Results: There was an excellent positive correlation between liver fat content and serum levels of ALT (r = 0.73, p ,0.0001). All subjects with ALT values .37 U/L had hepatic steatosis (PPV: 100%) and none of the subjects with ALT ,20 U/L had steatosis (NPV: 100%). ROC curves were created, obtaining that the cutoff value that represents the normal threshold for the diagnosis of NAFLD was ALT: 23 U / L (sensitivity: 94.67%, specificity 73.91%, PPV: 85.84%, NPV: 89.47%). Conclusion: This study shows that serum ALT levels could be a reliable biomarker of NAFLD if the upper limit of normal for ALT is set at 23 U/L.

Tu1051 Noninvasive Assessment of Liver Fibrosis by Measurement of Lf Index in Patients With Chronic Viral Hepatitis

Introduction: Epidemiological studies have shown that nonalcoholic fatty liver disease (NAFLD) not only is a possible precursor of cirrhosis, but also has been associated with metabolic syndrome, diabetes and cardiovascular disease. There is a need to find a biomarker which proves to be reliable, non-invasive, and easy to perform in clinical practice. Our aim was to know whether serum alanine aminotransferase (ALT) value is a reliable biomarker of liver fat content in subjects with NAFLD in the general population, and to determine if the current threshold of normality for ALT is appropriate to assess the presence of liver fat in these subjects. Methods: This is a cross-sectional, randomized, prospective, populationbased study. We studied 120 healthy subjects attending health screening centers, alcohol consumption less than 50 g/week. Subjects underwent blood tests including aminotransferases. Viral hepatitis, autoimmune, drugs and others causes of liver disease were excluded. Measurements: quantification of liver fat content by spectroscopy 1H MR with magnetic field strength of 3 tesla. We used a cut off value .5% of liver fat content as the upper limit of normal for the diagnosis of hepatic steatosis (1). Serum ALT levels by commercially available kits. Results: There was an excellent positive correlation between liver fat content and serum levels of ALT (r = 0.73, p ,0.0001). All subjects with ALT values .37 U/L had hepatic steatosis (PPV: 100%) and none of the subjects with ALT ,20 U/L had steatosis (NPV: 100%). ROC curves were created, obtaining that the cutoff value that represents the normal threshold for the diagnosis of NAFLD was ALT: 23 U / L (sensitivity: 94.67%, specificity 73.91%, PPV: 85.84%, NPV: 89.47%). Conclusion: This study shows that serum ALT levels could be a reliable biomarker of NAFLD if the upper limit of normal for ALT is set at 23 U/L.