Ultrasound in the detection of chronic liver disease (the "bright liver")

Utility of ultrasonography in a mouse model of non-alcoholic steatohepatitis induced by a choline-deficient, high-fat diet and dextran sulfate sodium

Background

Nonalcoholic steatohepatitis (NASH) is a chronic progressive liver disease that can progress to cirrhosis and hepatocellular carcinoma. The prevalence of NASH is increasing year by year. However, the etiology and progression of NASH, along with the processes leading to carcinogenesis, remain poorly understood. A range of animal models are used in research, but investigators have been unable to establish a model that results in tumorigenesis from a stable disease state. The present study aimed to create a stable, low-mortality model of NASH using abdominal ultrasonography (US) to assess NASH stage and diagnose liver tumors.

Methods

Thirty-four 19-week-old male C57BL/6J mice were fed a choline-deficient, high-fat (CDHF) diet. Twenty animals were given seven courses of 0.8 % dextran sulfate sodium (DSS) for 7 days followed by 10 days of MilliQ water (CDHF+DSS group). The remaining 14 animals drank only MilliQ water (CDHF group). All animals were weighed weekly and US was performed on Days 35 and 120. After necropsy, samples were taken for biochemical analysis and histopathological evaluation.

Results

The CDHF+DSS group had significantly lower body weight on Days 35 and 120, and significantly higher liver/body weight (%) on Day 35 compared to the CDHF group. US on Days 35 and 120 revealed significantly shorter long intestine and higher colonic histological score in the CDHF+DSS group compared to the CDHF group. IL-1β and IL-6 levels in the large intestinal tissue were significantly higher in the CDHF+DSS group.

Conclusions

A stable, low-mortality model of NASH was created with a CDHF diet and intermittent 0.8 % DSS. Abdominal US can assess the degree of fatty degeneration and evaluate liver tumorigenesis without necropsy. This assessment procedure will reduce the number of mice killed unnecessarily during experiments, thereby contributing to animal welfare.

Novel multi-parametric diagnosis of non-alcoholic fatty liver disease using ultrasonography, body mass index, and Fib-4 index

BACKGROUND

Shear wave speed (SWS), shear wave dispersion (SWD), and attenuation imaging (ATI) are new diagnostic parameters for non-alcoholic fatty liver disease. To differentiate between non-alcoholic steatohepatitis (NASH) and non-alcoholic fatty liver (NAFL), we developed a clinical index we refer to as the “NASH pentagon” consisting of the 3 abovementioned parameters, body mass index (BMI), and Fib-4 index.

AIM

To investigate whether the area of the NASH pentagon we propose is useful in discriminating between NASH and NAFL.

METHODS

This non-invasive, prospective, observational study included patients diagnosed with fatty liver by abdominal ultrasound between September 2021 and August 2022 in whom shear wave elastography, SWD, and ATI were measured. Histological diagnosis based on liver biopsy was performed in 31 patients. The large pentagon group (LP group) and the small pentagon group (SP group), using an area of 100 as the cutoff, were compared; the NASH diagnosis rate was also investigated. In patients with a histologically confirmed diagnosis, receiver-operating characteristic (ROC) curve analyses were performed.

RESULTS

One hundred-seven patients (61 men, 46 women; mean age 55.1 years; mean BMI 26.8 kg/m²) were assessed. The LP group was significantly older (mean age: 60.8 ± 15.2 years vs 46.4 ± 13.2 years; P < 0.0001). Twenty-five patients who underwent liver biopsies were diagnosed with NASH, and 6 were diagnosed with NAFL. On ROC curve analyses, the areas under the ROC curves for SWS, dispersion slope, ATI value, BMI, Fib-4 index, and the area of the NASH pentagon were 0.88000, 0.82000, 0.58730, 0.63000, 0.59333, and 0.93651, respectively; the largest was that for the area of the NASH pentagon.

CONCLUSION

The NASH pentagon area appears useful for discriminating between patients with NASH and those with NAFL.

Non-invasive imaging biomarkers for liver steatosis in non-alcoholic fatty liver disease: present and future

Non-alcoholic fatty liver disease is currently the most common chronic liver disease, affecting up to 25% of the global population. Simple fatty liver, in which fat is deposited in the liver without fibrosis, has been regarded as a benign disease in the past, but it is now known to be prognostic. In the future, more emphasis should be placed on the quantification of liver fat. Traditionally, fatty liver has been assessed by histological evaluation, which requires an invasive examination; however, technological innovations have made it possible to evaluate fatty liver by non-invasive imaging methods, such as ultrasonography, computed tomography, and magnetic resonance imaging. In addition, quantitative as well as qualitative measurements for the detection of fatty liver have become available. In this review, we summarize the currently used qualitative evaluations of fatty liver and discuss quantitative evaluations that are expected to further develop in the future.

Increased brain-derived neurotrophic factor in the serum of persons with nonalcoholic fatty liver disease

The increasing prevalence of nonalcoholic fatty liver disease (NAFLD) is a global health problem. In recent years, the inhibitory effect of brain-derived neurotrophic factor (BDNF) on diabetes mellitus and fatty liver has been clarified. The purpose of this study was to analyze the relationship between serum BDNF and NAFLD which caused by abnormal metabolism of glucose and lipids. This cross-sectional study involved 429 participants (mean age, 63.5 years: men, 38.5%) with low alcohol intake. Of the participants, those who had an increase in echogenicity of the liver parenchyma and hepato-renal contrast on ultrasonography were classified as the NAFLD group (n = 88), and the others were classified as the normal (n = 341) group. The NAFLD group was further classified into a mild group (n = 60) and a severe group (n = 28) based on the intensity of echogenicity and visualization of the hepatic vessels and diaphragm. Median BDNF levels were higher in the NAFLD group than the normal group (35.5 vs. 42.3 ng/mL, p < 0.01). Furthermore, BDNF levels tended to be associated with the severity of NAFLD (p < 0.01). In addition to the univariate analysis, in the sex- and age-adjusted model, there was a significant association between the BDNF levels and NAFLD severity (p < 0.01). The fully adjusted regression analysis also showed a positive association between the serum BDNF level and NAFLD (p < 0.01). These results suggest that NAFLD patients have a compensatory increase in circulating BDNF levels.

Quantitative Assessment of Fatty Liver using Ultrasound with Normalized Local Variance Technique

PURPOSE

 To assess the diagnostic performance of the normalized local variance (NLV) ultrasound technique in the detection of the fatty liver using histopathology as a reference standard.

MATERIALS AND METHODS

 We prospectively enrolled 194 consecutive patients with clinical suspicion of diffuse liver disease or history of liver transplantation. Conventional grayscale ultrasound and NLV examinations were performed and immediately followed by liver biopsies. The degrees of fatty liver, necroinflammatory activity, and fibrosis stage were evaluated by histopathological assessment. The diagnostic performance of the NLV values in detecting each grade of fatty liver was determined using receiver operating characteristics analyses, and multivariate linear regression analyses were performed to identify variables significantly associated with the NLV values.

RESULTS

 The number of patients in each degree of fatty liver and hepatic fibrosis was 118/37/26/13 and 81/68/24/6/14 for none/mild/moderate/severe steatosis and F0 / F1/F2 / F3/F4 fibrosis on histopathological examinations, respectively. The area under the receiver operating characteristics curve and optimal cut-off NLV value for detecting fatty liver of varying degrees were 0.911 and 1.095 for ≥ S1, 0.974 and 1.055 for ≥ S2, and 0.954 and 1.025 for ≥ S3, respectively. Multivariate analyses revealed that not fibrosis or inflammation but rather the degree of steatosis was associated with the NLV value.

CONCLUSION

 The NLV value demonstrated excellent diagnostic performance for detecting varying degrees of fatty liver, and the degree of steatosis on histopathological examinations was the only significant factor affecting the NLV value.

Pathological findings of liver steatosis that is difficult to evaluate with ultrasound

Although new ultrasound (US) methods able to quantitatively assess liver fat content have been recently developed, B-mode US is still the major method for detecting liver steatosis during medical checkups. However, some pathological cases yield false-positive or false-negative liver steatosis results using B-mode US. In addition, histologically, the degree of fat deposits and the size of fat droplets in the liver can affect the sensitivity and specificity of the diagnosis of liver steatosis using B-mode US. As B-mode US evaluation of fatty liver relies on operator expertise, the operator should be aware that there are some cases of liver steatosis that are difficult to evaluate with B-mode US. Here, we describe the pathological findings of liver steatosis that is difficult to evaluate with US.

The ultrasound-guided attenuation parameter is useful in quantification of hepatic steatosis in non-alcoholic fatty liver disease

Aim

To determine the utility of the ultrasound‐guided attenuation parameter (UGAP) for quantifying hepatic steatosis in non‐alcoholic fatty liver disease (NAFLD).

Methods

Subjects were 84 patients with NAFLD (53 men, 31 women; mean age 54 [20–81] years) who underwent liver biopsy and ultrasonography using a GE LOGIQ E9 system and C1‐6 probe at our hospital between 2017 and 2020. B‐Mode imaging of segment V in the liver was acquired and echo attenuation was assessed using UGAP. Steatosis score (S0: <5%; S1: 5%–33%; S2: 34%–66%; S3: ≥67%) from liver specimens was compared with the attenuation coefficient (AC; dB/cm/MHz) using UGAP.

Results

Steatosis score was S0 for 9 patients, S1 for 40, S2 for 21, and S3 for 14. AC by steatosis score was 0.52 ± 0.07, 0.63 ± 0.07, 0.74 ± 0.06, and 0.78 ± 0.06 dB/cm/MHz for S0, S1, S2, and S3, respectively. AC by UGAP differed significantly between S0 and S1, S0 and S2, S0 and S3, S1 and S2, and S1 and S3 (all P < 0.01), demonstrating a significant increase with steatosis score. Receiver operating characteristic analysis showed good diagnostic performance of UGAP for patients with steatosis score ≥1, ≥2, and ≥3 (AUROC = 0.94, 0.95, and 0.88, respectively). Liver fat content (%) from liver specimens and AC (r = 0.81, P < 0.01) showed a significant positive correlation.

Conclusion

UGAP is useful for quantifying hepatic steatosis in patients with NAFLD.

Effect of skin-capsular distance on controlled attenuation parameter for diagnosing liver steatosis in patients with nonalcoholic fatty liver disease

The effect of the skin-capsular distance (SCD) on the controlled attenuation parameter (CAP) for diagnosis of liver steatosis in patients with nonalcoholic fatty liver disease (NAFLD) remains unclear. The SCD was measured using B-mode ultrasound, and the CAP was measured using the M probe of FibroScan®. According to the indications of the M probe, 113 patients with an SCD of ≤ 25 mm were included in the present study. The association between the SCD and CAP was investigated, and the diagnostic performance of the SCD-adjusted CAP was tested. The SCD showed the most significant positive correlation with the CAP (ρ = 0.329, p < 0.001). In the multiple regression analysis, the SCD and serum albumin concentration were associated with the CAP, independent of pathological liver steatosis. According to the multivariate analysis, two different formulas were developed to obtain the adjusted CAP using the SCD and serum albumin concentration as follows: adjusted CAP (dB/m) = CAP - (5.26 × SCD) and adjusted CAP (dB/m) = CAP - (5.35 × SCD) - (25.77 × serum albumin concentration). The area under the receiver operating characteristic curve for diagnosis of a steatosis score ≥ 2 of adjusted CAP was 0.678 and 0.684 respectively, which were significantly greater than the original CAP (0.621: p = 0.030 and p = 0.024). The SCD is associated with the CAP independent of liver steatosis. Adjustment of the CAP using the SCD improves the diagnostic performance of the CAP in NAFLD.

Ultrasonographic grayscale findings related to fibrosis in patients with non-alcoholic fatty liver disease: comparison with transient elastography and Fib-4 index

PURPOSE

Fibrosis is a predictor of mortality in patients with non-alcoholic fatty liver disease (NAFLD). In our institution, abdominal ultrasonography has been performed based on a unified method consisting of 25 images. We investigated ultrasonographic grayscale findings related to fibrosis in patients with NAFLD.

METHODS

This retrospective study comprised 41 cases of pathologically proven fatty liver between January 2015 and September 2020. A total of 26 ultrasonographic findings were subjectively evaluated. These findings, transient elastography (TE) with M probe, and FIB-4 index were compared with fibrosis stage.

RESULTS

The frequency of roughness of the dorsal side of the surface (p < 0.001), heterogenicity of the parenchyma (p = 0.003), narrowing of the hepatic vein (p = 0.004), and splenomegaly (p < 0.001) were strongly correlated with the fibrosis stage. Logistic regression analysis for stage ≥ 3 showed narrowing of the hepatic vein (odds ratio [OR] 5.860, p = 0.031) and splenomegaly (OR 6.290, p = 0.028). Logistic regression analysis for stage 4 showed roughness of the ventral side of the surface (OR 42.0, p = 0.019). The AUROC for stage 3 and stage 4 with the number of positive ultrasonographic findings was 0.856, and 0.940, respectively. The AUROC for F3 and F4 with TE was 0.831 and 0.861, respectively. The AUROC for stage 3 and stage 4 with FIB-4 index was 0.815 and 0.806, respectively.

CONCLUSIONS

Narrowing of the hepatic vein, roughness of the dorsal side of the surface, heterogenicity of the parenchyma, and splenomegaly and their combination could predict fibrosis in patients with NAFLD.

Quantitative Evaluation of Hepatic Steatosis Using Normalized Local Variance in a Rat Model: Comparison with Histopathology as the Reference Standard

Objective

To evaluate the diagnostic performance of the normalized local variance (NLV) ultrasound technique in the assessment of hepatic steatosis, and to identify the factors that influence the NLV value using histopathological examination as the reference standard.

Materials and Methods

Forty male Sprague-Dawley rats were fed a methionine-choline-deficient diet for variable periods (0, 2, 4, 6, 8, 10, or 12 days or 2, 3, or 4 weeks; four rats per group). At the end of each diet duration, magnetic resonance spectroscopy (MRS) and NLV examination were performed. Thereafter, the rats were sacrificed and their livers were histopathologically evaluated. Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic capability of the NLV value in the detection of varying degrees of hepatic steatosis. Univariate and multivariate linear regressions were used to determine the factors associated with the NLV value.

Results

The areas under the ROC curve for the detection of mild, moderate, and severe hepatic steatosis were 0.953, 0.896, and 0.735, respectively. The NLV value showed comparable diagnostic performance to that of MRS in the detection of ≥ mild or ≥ moderate hepatic steatosis. Multivariate linear regression analysis revealed that the degree of hepatic steatosis was the only significant factor affecting the NLV value (p < 0.001).

Conclusion

The NLV value of ultrasound demonstrated satisfactory diagnostic performance in the assessment of varying degrees of hepatic steatosis. The degree of hepatic steatosis was the only significant factor that affected the NLV value.

The Role of Multiparametric US of the Liver for the Evaluation of Nonalcoholic Steatohepatitis

Background Nonalcoholic steatohepatitis (NASH) is diagnosed with histopathologic testing, but noninvasive surrogate markers are desirable for screening patients who are at high risk of NASH. Purpose To investigate the diagnostic performance of dispersion slope, attenuation coefficient, and shear-wave speed measurements obtained using two-dimensional (2D) shear-wave elastography (SWE) in assessing inflammation, steatosis, and fibrosis and in the noninvasive diagnosis of NASH in patients suspected of having nonalcoholic fatty liver disease (NAFLD). Materials and Methods This prospective study collected data from 120 consecutive adults who underwent liver biopsy for suspected NAFLD and were enrolled between April 2017 and March 2019. Three US parameters (dispersion slope [(m/sec)/kHz], attenuation coefficient [dB/cm/MHz], and shear-wave speed [in meters per second]) were measured using a 2D SWE system immediately before biopsy. The biopsy specimens were scored by one expert pathologist according to the Nonalcoholic Steatohepatitis Clinical Research Network criteria (119 participants underwent a histologic examination). Diagnostic performance was assessed using the area under the receiver operating characteristic curve (AUC) for the categories of inflammation, steatosis, and fibrosis. Results One hundred eleven adults (mean age, 53 years ± 18 [standard deviation]; 57 men) underwent a US examination. Dispersion slope enabled the identification of lobular inflammation, with an AUC of 0.95 (95% confidence interval [CI]: 0.91, 0.10) for an inflammation grade greater than or equal to A1 (mild), 0.81 (95% CI: 0.72, 0.89) for an inflammation grade greater than or equal to A2 (moderate), and 0.85 (95% CI: 0.74, 0.97) for an inflammation grade equal to A3 (marked). Attenuation coefficient enabled the identification of steatosis, with an AUC of 0.88 (95% CI: 0.80, 0.97) for steatosis grade greater than or equal to S1 (mild), 0.86 (95% CI: 0.79, 0.93) for steatosis grade greater than or equal to S2 (moderate), and 0.79 (95% CI: 0.68, 0.89) for steatosis grade equal to S3 (severe). Shear-wave speed enabled the identification of fibrosis, with an AUC of 0.79 (95% CI: 0.69, 0.88) for fibrosis stage greater than or equal to F1 (portal fibrosis), 0.88 (95% CI: 0.82, 0.94) for fibrosis stage greater than or equal to F2 (periportal fibrosis), 0.90 (95% CI: 0.84, 0.96) for fibrosis stage greater than or equal to F3 (septal fibrosis), and 0.95 (95% CI: 0.91, 0.99) for fibrosis stage equal to F4 (cirrhosis). The combination of dispersion slope, attenuation coefficient, and shear-wave speed showed an AUC of 0.81 (95% CI: 0.71, 0.91) for the diagnosis of NASH. Conclusion Dispersion slope, attenuation coefficient, and shear-wave speed were found to be useful for assessing lobular inflammation, steatosis, and fibrosis, respectively, in participants with biopsy-proven nonalcoholic fatty liver disease. © RSNA, 2020 Online supplemental material is available for this article.

Assessment of hepatic steatosis by using attenuation imaging: a quantitative, easy-to-perform ultrasound technique

OBJECTIVES

To evaluate the diagnostic performance of attenuation imaging (ATI) in the detection of hepatic steatosis compared with a histopathology gold standard.

METHODS

We prospectively enrolled 108 consecutive patients (35 males; median age, 54.0 years) who underwent percutaneous liver biopsy for evaluation of diffuse liver disease between January 2018 and November 2018 in a tertiary academic center. Grayscale ultrasound examination with ATI was performed just before biopsy, and an attenuation coefficient (AC) was obtained from each patient. The degree of hepatic steatosis, fibrosis stage, and necroinflammatory activity were assessed on histopathologic examination. The significant factor associated with the AC was found by a linear regression analysis, and the diagnostic performance of the AC for the classification into each hepatic steatosis stage was evaluated by receiver operating characteristic (ROC) analysis.

RESULTS

The distribution of hepatic steatosis grade on histopathology was 53/11/22/16/6 for none/mild (< 10%)/mild (≥ 10%)/moderate/severe steatosis, respectively. The area under the ROC curve, sensitivity, specificity, and optimal cutoff AC value for detection of hepatic steatosis ranged from 0.843-0.926, 74.5-100.0%, 77.4-82.8%, and 0.635-0.745, respectively. Multivariate analysis revealed that the degree of steatosis was the only significant determinant factor for the AC.

CONCLUSIONS

The AC from ATI provided good diagnostic performance in detecting the varying degrees of hepatic steatosis. The degree of steatosis was the only significant factor affecting the AC, whereas fibrosis and inflammation were not.

KEY POINTS

• Attenuation imaging (ATI) is based on two-dimensional grayscale ultrasound images that can incorporate into routine ultrasound examinations with less than 2 min of acquisition time. • ATI provided good diagnostic performance in detecting the varying degrees of hepatic steatosis with an area under the ROC curves ranging from 0.843 to 0.926, and there was no technical failure in this study indicating high applicability of this technique. • The degree of hepatic steatosis was the only significant factor affecting the result of ATI examination.

Quantitative Hepatic Fat Quantification in Non-alcoholic Fatty Liver Disease Using Ultrasound-Based Techniques: A Review of Literature and Their Diagnostic Performance

Non-alcoholic fatty liver disease is a condition that is characterized by the presence of >5% fat in the liver and affects more than one billion people worldwide. If adequate and early precautions are not taken, non-alcoholic fatty liver disease can progress to cirrhosis and death. The current reference standard for detecting hepatic steatosis is a liver biopsy. However, because of the potential morbidity associated with liver biopsies, non-invasive imaging biomarkers have been extensively investigated. Magnetic resonance imaging-based methods have proven accuracy in quantifying liver steatosis; however, these techniques are costly and have limited availability. Ultrasound-based quantitative imaging techniques are increasingly utilized because of their widespread availability, ease of use and relative cost-effectiveness. Several ultrasound-based liver fat quantification techniques have been investigated, including techniques that measure changes in the acoustic properties of the liver caused by the presence of fat. In this review, we focus on quantitative ultrasound approaches and their diagnostic performance in the realm of non-alcoholic fatty liver disease.

The B-Mode Image-Guided Ultrasound Attenuation Parameter Accurately Detects Hepatic Steatosis in Chronic Liver Disease

The purpose of our study was to evaluate the diagnostic accuracy of the ultrasound-guided attenuation parameter (UGAP) for the detection of hepatic steatosis in comparison with the controlled attenuation parameter (CAP), using histopathology as the reference standard. We prospectively analyzed 163 consecutive chronic liver disease patients who underwent UGAP, CAP, computed tomography and a liver biopsy on the same day between April 2016 and July 2017. Radiofrequency signals corresponding to the images were compensated by the reference signal previously measured from the uniform phantom with known attenuation (0.44 dB/cm/MHz). The attenuation coefficient was calculated from the signals' decay slope. The median attenuation coefficient values in patients with S0 (n = 62), S1 (n = 63), S2 (n = 23) and S3 grade (n = 15) were 0.485, 0.560, 0.660 and 0.720, respectively. Significant correlations were found between attenuation coefficient and percentage steatosis, CAP values and liver-to-spleen computed tomography attenuation ratio (p < 0.001). The areas under the receiver operating characteristic curve of UGAP for identifying ≥S1, ≥S2 and ≥S3 were 0.900, 0.953 and 0.959, respectively, which were significantly better than the results obtained with CAP for identifying ≥S2 and ≥S3. In conclusion, UGAP had high diagnostic accuracy for detecting hepatic steatosis in patients with chronic liver disease.

Ultrasonography and Computed Tomography in Diffuse Liver Disease with Cholestasis

Ultrasonography (US) and computed tomography (CT) were performed on respectively 67 and 42 (altogether 72) patients, for the assessment of intrahepatic cholestasis. The diagnostic ability to differentiate between malignant (17 patients) and benign (55 patients) liver disease was analyzed. Coarse echogenicity of the liver led to inconclusive results in differentiating between cirrhosis (2 out of 29 patients) and malignant infiltration (4 out of 15 patients) by US. Other benign liver diseases in 23 patients, including acute hepatitis, chronic active hepatitis, fatty liver, and liver congestion, were correctly interpreted as benign. CT correctly disclosed malignant liver disease in all cases. A false positive diagnosis of malignancy was encountered in 4 (out of 17) patients with decompensated hepatic cirrhosis because of non-homogeneous expansive areas on CT in 3 cases. The true cause was in 2 patients non-uniform fatty infiltration, and in one patient with acute hepatitis A, small hypodense lesions. Among cholestatic patients, decompensated cirrhosis and malignant liver infiltration could not always be differentiated on US or CT.

Ultrasonography and Scintigraphy of the Liver in Focal and Diffuse Disease

In a clinical series the accuracy of standard colloid scintigraphy and gray-scale ultrasonography in investigations for liver disease was evaluated. The results of 246 investigations in which both methods were utilized were reviewed and classified according to diagnosis and follow-up. In focal disease the sensitivity was 0.90 for scintigraphy, and 0.83 for ultrasonography; ultrasonography had the higher specificity, 0.94 compared with 0.77 for scintigraphy. In diffuse disease the sensitivity was found to be low for both methods, about 0.60, while specificity was high, 0.86 for scintigraphy and 0.92 for ultrasonography. Decreased liver function in diffuse liver disease as reflected by bone marrow uptake at scintigraphy was not found to have any influence on the degree of sensitivity of ultrasonography.

Definitions of Normal Liver Fat and the Association of Insulin Sensitivity with Acquired and Genetic NAFLD-A Systematic Review

Non-alcoholic fatty liver disease (NAFLD) covers a spectrum of disease ranging from simple steatosis (NAFL) to non-alcoholic steatohepatitis (NASH) and fibrosis. “Obese/Metabolic NAFLD” is closely associated with obesity and insulin resistance and therefore predisposes to type 2 diabetes and cardiovascular disease. NAFLD can also be caused by common genetic variants, the patatin-like phospholipase domain-containing 3 (PNPLA3) or the transmembrane 6 superfamily member 2 (TM6SF2). Since NAFL, irrespective of its cause, can progress to NASH and liver fibrosis, its definition is of interest. We reviewed the literature to identify data on definition of normal liver fat using liver histology and different imaging tools, and analyzed whether NAFLD caused by the gene variants is associated with insulin resistance. Histologically, normal liver fat content in liver biopsies is most commonly defined as macroscopic steatosis in less than 5% of hepatocytes. In the population-based Dallas Heart Study, the upper 95th percentile of liver fat measured by proton magnetic spectroscopy (¹H-MRS) in healthy subjects was 5.6%, which corresponds to approximately 15% histological liver fat. When measured by magnetic resonance imaging (MRI)-based techniques such as the proton density fat fraction (PDFF), 5% macroscopic steatosis corresponds to a PDFF of 6% to 6.4%. In contrast to “Obese/metabolic NAFLD”, NAFLD caused by genetic variants is not associated with insulin resistance. This implies that NAFLD is heterogeneous and that “Obese/Metabolic NAFLD” but not NAFLD due to the PNPLA3 or TM6SF2 genetic variants predisposes to type 2 diabetes and cardiovascular disease.

Quantitative Ultrasound for Staging of Hepatic Steatosis in Patients on Home Parenteral Nutrition Validated with Magnetic Resonance Spectroscopy: A Feasibility Study

Patients on home parenteral nutrition are at risk for developing liver dysfunction, which is due partly to the accumulation of lipids in the liver (steatosis) and may progress to end-stage liver disease with overt liver failure. Therefore, a timely diagnosis with easy access to repeated assessment of the degree of liver steatosis is of great importance. A pilot study was performed in 14 patients on long-term home parenteral nutrition using the computer-aided ultrasound method. Ultrasound radio frequency data were acquired using a phased array transducer and were converted into conventional B-mode images. All patients were subjected to proton magnetic resonance spectroscopy measurement of liver fat content for reference. Computer-aided ultrasound parameters similar to those in a previous validation study in cows revealed significant correlations with fat content measured by magnetic resonance spectroscopy. The most significant parameters were the residual attenuation coefficient (R = 0.95, p < 0.001) and the lateral speckle size (R = 0.77, p = 0.021). These findings indicate the potential usefulness of computer-aided ultrasound for staging of hepatic steatosis.

Quantification of Hepatorenal Index for Computer-Aided Fatty Liver Classification with Self-Organizing Map and Fuzzy Stretching from Ultrasonography

Accurate measures of liver fat content are essential for investigating hepatic steatosis. For a noninvasive inexpensive ultrasonographic analysis, it is necessary to validate the quantitative assessment of liver fat content so that fully automated reliable computer-aided software can assist medical practitioners without any operator subjectivity. In this study, we attempt to quantify the hepatorenal index difference between the liver and the kidney with respect to the multiple severity status of hepatic steatosis. In order to do this, a series of carefully designed image processing techniques, including fuzzy stretching and edge tracking, are applied to extract regions of interest. Then, an unsupervised neural learning algorithm, the self-organizing map, is designed to establish characteristic clusters from the image, and the distribution of the hepatorenal index values with respect to the different levels of the fatty liver status is experimentally verified to estimate the differences in the distribution of the hepatorenal index. Such findings will be useful in building reliable computer-aided diagnostic software if combined with a good set of other characteristic feature sets and powerful machine learning classifiers in the future.

The prevalence of bright liver echo pattern in patients with chronic hepatitis C: correlation with steatosis and fibrosis

PURPOSE

To evaluate the prevalence of bright liver echo pattern (BLP) on ultrasonography and its correlation with liver steatosis (LS), and fibrosis in patients with chronic hepatitis C. The usefulness of detecting skip areas for steatosis diagnosis has also been evaluated.

METHODS

The study included 88 patients with chronic hepatitis C (55 men, 33 women, average age 45.7 ± 11.2 years). Ultrasound examination was performed in all patients before liver biopsy. The presence of BLP was assessed and graded from 1 to 3. Hypoechogenic areas (skip areas) around the gallbladder or near the portal vein were also evaluated. Hepatic fibrosis was assessed using the Ishak fibrosis score. Steatosis was graded as follows: 1, 2, 3 (<30, 30-70, >70 % of hepatocytes affected, respectively).

RESULTS

Fifty-three of the 88 patients (60 %) showed BLP (40 grade 1, 13 grades 2 or 3). Skip areas were found in 14 patients (16 %). Histological steatosis was observed in 40 patients (45 %) and in 10 of them (25 %) was grades 2 and 3 (4 and 6 patients, respectively). As regards fibrosis, 2 patients showed F0, 34 F1, 28 F2, 20 F3, 4 F4, none of them F5 and F6. BLP of grades 2 or 3 and presence of skip areas were strongly correlated with LS (P = 0.00007 and P = 0.00003, respectively). No correlation was found between BLP and fibrosis. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of BLP for LS were 75, 50, 56, 68 and 61 %, respectively. When BLP of grades 2 and 3 and LS of 30 % or more were correlated, the sensitivity, specificity, PPV, NPV and accuracy of BLP were 72, 96, 61, 96 and 90 %, respectively. As regards skip areas the sensitivity, specificity, PPV, NPV and accuracy for LS were 35, 100, 100, 64 and 70 %, respectively.

CONCLUSIONS

In a well-defined group of patients with chronic hepatitis C, the detection of BLP grades 2 and 3 has a good sensitivity and high specificity for high grades of steatosis. A high specificity but low sensitivity for liver steatosis was also found for skip areas, whereas mild fibrosis does not seem to correlate with the hyperechogenicity of the liver.

Steatosis and steatohepatitis: complex disorders

Non-alcoholic fatty liver disease (NAFLD) which includes steatosis and steatohepatitis, in particular non-alcoholic steatohepatitis (NASH), is a rising health problem world-wide and should be separated from alcoholic steatohepatitis (ASH). NAFLD is regarded as hepatic manifestation of the metabolic syndrome (MetSy), being tightly linked to obesity and type 2 diabetes mellitus (T2DM). Development of steatosis, liver fibrosis and cirrhosis often progresses towards hepatocellular carcinogenesis and frequently results in the indication for liver transplantation, underlining the clinical significance of this disease complex. Work on different murine models and several human patients studies led to the identification of different molecular key players as well as epigenetic factors like miRNAs and SNPs, which have a promoting or protecting function in AFLD/ASH or NAFLD/NASH. To which extent they might be translated into human biology and pathogenesis is still questionable and needs further investigation regarding diagnostic parameters, drug development and a better understanding of the genetic impact. In this review we give an overview about the currently available knowledge and recent findings regarding the development and progression of this disease.

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

BACKGROUND & AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Nonalcoholic fatty liver disease: an emerging threat to obese and diabetic individuals

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in the Western world and its incidence is increasing rapidly. NAFLD is a spectrum ranging from simple steatosis, which is relatively benign hepatically, to nonalcoholic steatohepatitis (NASH), which can progress to cirrhosis. Obesity, insulin resistance, type 2 diabetes mellitus, and dyslipidemia are the most important risk factors for NAFLD. Due to heavy enrichment with metabolic risk factors, individuals with NAFLD are at significantly higher risk for cardiovascular disease. Individuals with NAFLD have higher incidence of type 2 diabetes. The diagnosis of NAFLD requires imaging evidence of hepatic steatosis in the absence of competing etiologies including significant alcohol consumption. Liver biopsy remains the gold standard for diagnosing NASH and for determining prognosis. Weight loss remains a cornerstone of treatment. Weight loss of ∼5% is believed to improve steatosis, whereas ∼10% weight loss is necessary to improve steatohepatitis. A number of pharmacologic therapies have been investigated to treat NASH, and agents such as vitamin E and thiazolidinediones have shown promise in select patient subgroups.

Accuracy of routine clinical ultrasound for staging of liver fibrosis

Objective:

To determine the diagnostic accuracy of routine clinical ultrasound in the staging of liver fibrosis in chronic viral hepatitis.

Materials and Methods:

A retrospective evaluation of the ultrasound images of 156 patients with chronic viral hepatitis who underwent liver biopsy was performed. Two radiologists in consensus, blind to the biopsy results and clinical details, evaluated the ultrasound images for liver fibrosis. The readers specifically assessed three features — surface nodularity, liver edge, and parenchymal echotexture — with scores of 0 to 3 (0 = normal, 1 = mild, 2 = moderate, 3 = severe). Accuracies of each sonographic feature for the detection of mild fibrosis and above (≥F1), significant fibrosis (≥F2), severe fibrosis (≥F3), and cirrhosis (F4) were determined with histopathology as the reference standard.

Results:

Fibrosis was present in 99 patients (F1=34, F2=20, F3=22, and F4=23) and absent in 57 patients. The sensitivities for the detection of significant fibrosis with surface nodularity, liver edge, and parenchymal echotexture were 57%, 15%, and 41%, respectively. The accuracies for the detection of ≥F1, ≥F2, ≥F3, and F4 stages were 50.5%, 59%, 59%, and 65% for liver surface, 51%, 53%, 54%, and 55% for liver edge, and 58%, 59%, 63%, and 63% for parenchyma echotexture, respectively. The combined scores from all three features had accuracies of 56%, 59%, 62%, and 66% for the detection of ≥F1, ≥F2, ≥F3, and F4, respectively.

Conclusion:

Routine clinical ultrasound is a not a sensitive predictor of early fibrosis in chronic viral hepatitis. Surface nodularity is the most sensitive sonographic feature for the detection of significant fibrosis and routine clinical ultrasound is the most useful for the detection of cirrhosis.

Non-invasive determination of hepatic steatosis by acoustic structure quantification from ultrasound echo amplitude

AIM: To use leptin-deficient (ob/ob) mice with demonstrated differences in steatosis levels to test a new diagnostic method using the acoustical structure quantification (ASQ) mode and the associated analytical parameter, “focal disturbance ratio” (FD-ratio).

METHODS: Nine ob/ob mice, at 5, 8, and 12 wk of age (n = 3 in each age group), were used as models for hepatic steatosis. Echo signals obtained from ultrasonography in the mice were analyzed by ASQ, which uses a statistical analysis of echo amplitude to estimate inhomogeneity in the diagnostic region. FD-ratio, as calculated from this analysis, was the focus of the present study. FD-ratio and fat droplet areas and sizes were compared between age groups.

RESULTS: No fibrosis or inflammation was observed in any of the groups. The fat droplet area significantly (P < 0.01) increased with age from 1.25% ± 0.28% at 5 wk to 31.07% ± 0.48% at 8 wk to 51.69% ± 3.19% at 12 wk. The median fat droplet size also significantly (P < 0.01) increased with age, from 1.33 (0.55-10.52) μm at 5 wk, 2.82 (0.61-44.13) μm at 8 wk and 6.34 (0.66-81.83) μm at 12 wk. The mean FD-ratio was 0.42 ± 0.11 at 5 wk, 0.11 ± 0.05 at 8 wk, and 0.03 ± 0.02 at 12 wk. The FD-ratio was significantly lower at 12 wk than at 5 wk and 8 wk (P < 0.01). A significant negative correlation was observed between the FD-ratio and either the fat droplet area (r = -0.7211, P = 0.0017) or fat droplet size (r = -0.9811, P = 0.0052).

CONCLUSION: This tool for statistical analysis of signals from ultrasonography using the FD-ratio can be used to accurately quantify fat in vivo in an animal model of hepatic steatosis, and may serve as a quantitative biomarker of hepatic steatosis.

Transcutaneous vs. intraoperative quantitative ultrasound for staging bovine hepatic steatosis

The aim of this study was to test the hypothesis that quantitative analysis of transcutaneous (Transc) ultrasound (US) images can predict the liver fat content with similar accuracy and precision as using intraoperative (Intraop) US. The second goal was to investigate if a tissue mimicking phantom (TMP) might be used as reference for automatic gain compensation (AGC) vs. depth instead of using the data of a set of cows without hepatic alterations. A study was performed in post partum dairy cows (N = 151), as an animal model of human nonalcoholic fatty liver disease (NAFLD), to test these hypotheses. Five Transc and five Intraop US liver images were acquired in each animal and a liver biopsy was taken. In liver tissue samples, triacylglycerol (TAG) content was measured by biochemical analysis and hepatic alterations, other than hepatic steatosis, were excluded by clinical examination. Several preprocessing steps were performed before the ultrasound tissue characteristics (UTC) parameters of B-mode images were derived. Stepwise multiple linear regression analysis was performed on a training set (N = 76) and the results were used on the test group (N = 75) to predict the TAG content in the liver. In all cases, the residual attenuation coefficient (ResAtt) was the only selected parameter. Receiver operating characteristics (ROC) analysis was applied to assess the performance and area under the curve (AUC) of predicting TAG and to compare the sensitivity and specificity of the methods used. High ROC values for AUC (95%), sensitivity (87%) and specificity (83%) for both Intraop and Transc applications with control group as well as with phantom-based AGC were obtained. Consequently, it can be concluded that Transc results are equivalent to Intraop results. Furthermore, equivalent ROC values, when using TMP AGC, indicates the potential use of TMP-based corrections instead of normal group-based corrections. The high predictive values indicate that noninvasive quantitative US has a great potential for staging and screening on hepatic steatosis in cows.

Nutrition, intestinal permeability, and blood ethanol levels are altered in patients with nonalcoholic fatty liver disease (NAFLD)

BACKGROUND

A role of an altered dietary pattern (e.g., a diet rich in sugar) but also alterations at the level of the intestinal barrier have repeatedly been discussed to be involved in the development and progression of nonalcoholic fatty liver disease (NAFLD).

AIMS

To determine if the nutritional intake, intestinal flora, and permeability and the development of NAFLD are related in humans.

METHODS

Ten controls and 20 patients with NAFLD ranging from simple steatosis to steatohepatitis were included in the study. Bacterial overgrowth, orocecal transit time, and intestinal permeability were assessed. Alcohol, endotoxin, and plasminogen activator inhibitor (PAI-) 1 concentration were determined in plasma. Nutritional intake was assessed using a dietary history.

RESULTS

Despite no differences in the prevalence of bacterial overgrowth and in the orocecal transit time, intestinal permeability, alcohol, and endotoxin levels in plasma were significantly higher in patients with NAFLD than in controls. Similar results were also found for PAI-1 plasma concentrations. Patients with NAFLD had a significantly higher intake of protein, total carbohydrates, and mono- as well as disaccharides than controls. PAI-1, endotoxin, and ALT plasma levels were positively related to total protein and carbohydrate intake.

CONCLUSIONS

Taken together, our results indicate that intestinal permeability, endogenous alcohol synthesis, and nutritional intake are markedly altered in patients with NAFLD.

Helicobacter Pylori DNA in Liver Tissues From Chronic Hepatitis C Egyptian Patients

Background

Hepatitis C virus (HCV) is considered the most common etiology of chronic liver disease in Egypt, which may progress to cirrhosis and hepatocellular carcinoma (HCC). Previous studies have documented an association between Helicobacter pylori (H. pylori) infection and liver cirrhosis with or without HCC. This study aimed to investigate the presence of H. pylori DNA in the liver tissue of Egyptian patients with chronic hepatitis C (CHC).

Methods

Fifty-two CHC Egyptian patients were enrolled in this study. Plasma anti-H. pylori IgG was assessed with ELISA. Liver biopsies were tested for presence of Helicobacter DNA using genus specific nested polymerase chain reaction (PCR) and species was identified by sequencing.

Results

Anti-H. pylori IgG was detected in 31/52 (59.6%) CHC patients while Helicobacter DNA was detected in 6 (11.5%) patients, all were H. Pylori by sequencing. Helicobacter DNA was more frequent in patients with high stage liver fibrosis (33.3%) than in those with low stage fibrosis (2.7%) (P = 0.006). There was no association between the presence of H. pylori DNA in the liver and age, gender of patients, liver function tests, AFP levels or viral load.

Conclusions

These data confirm the presence of H. pylori DNA in liver of some CHC Egyptian patients and suggest an association of this bacterium with progression of liver fibrosis.

Contribuição da ultrassonografia para o diagnóstico das alterações histopatológicas presentes na hepatite C crônica, com ênfase na esteatose hepática: Parte I

OBJETIVO: Avaliar a contribuição da ultrassonografia no estudo das alterações histopatológicas encontradas na hepatite crônica pelo vírus C, com ênfase para a esteatose hepática. MATERIAIS E MÉTODOS: Foram comparados os resultados dos exames ultrassonográficos do fígado de 192 pacientes portadores de hepatite crônica pelo vírus C, com os achados histopatológicos dos fragmentos obtidos por biópsia hepática. Todos os exames ultrassonográficos obedeceram a um mesmo protocolo, sendo analisados os seguintes critérios: ecogenicidade, ecotextura e atenuação. Os pacientes foram agrupados considerando-se os com alterações ultrassonográficas e os sem alterações ultrassonográficas, sendo comparados com as alterações histopatológicas presentes. RESULTADOS: Entre as alterações histopatológicas presentes, apenas os graus 0 e 3 de alteração arquitetural e a esteatose hepática apresentaram diferença estatística significante entre os dois grupos. Dentre os critérios ultrassonográficos avaliados, a atenuação foi o que apresentou melhor correlação com a esteatose hepática. CONCLUSÃO: Os resultados do trabalho demonstraram que, em pacientes com hepatite crônica pelo vírus C, a ultrassonografia apresentou limitações à caracterização das alterações histopatológicas, apresentando concordância regular com o diagnóstico de esteatose hepática. Destaca-se a capacidade do método em mostrar a probabilidade de inexistência de esteatose hepática, tendo em vista a especificidade de 77,9% e o valor preditivo negativo de 95,5%.

Crucial role of impaired Kupffer cell phagocytosis on the decreased Sonazoid-enhanced echogenicity in a liver of a nonalchoholic steatohepatitis rat model

AIMS

To evaluate the dynamics of Kupffer cell (KC) phagocytosis by performing both in vivo and in vitro studies using Sonazoid (GE Healthcare, Oslo) in a rat nonalcoholic steatohepatitis (NASH) model.

METHODS

Contrast enhanced ultrasonography (CEUS) was performed on a rat NASH model induced by a methionine choline deficient diet (MCDD) and control rats, and Sonazoid was used to measure the signal intensity in the liver parenchyma. The uptake of Sonazoid by the KCs was observed by intravital microscopy. Their phagocytic capability was evaluated in vitro using isolated and cultured KCs. The uptake of fluorescein isothiocyanate (FITC)-labeled latex beads was observed and quantitatively analyzed by flow cytometry.

RESULTS

In the MCDD group, liver parenchymal enhancement was reduced 20 min after the Sonazoid injection. Microscopic observation of the isolated and cultured KCs revealed that the number of phagocytosed Sonazoid microbubbles was significantly decreased. Confocal laser scanning microscopic (CLSM) observation showed a decrease in the uptake of the latex beads. A decreased phagocytic capacity in the MCDD group was suggested by the quantitative analysis using flow cytometry, as well as by intravital microscopy.

CONCLUSIONS

CEUS with Sonazoid is a powerful evaluation tool to diagnose NASH from an early stage of the disease.

Interactive vs. automatic ultrasound image segmentation methods for staging hepatic lipidosis

The aim of this study was to test the hypothesis that automatic segmentation of vessels in ultrasound (US) images can produce similar or better results in grading fatty livers than interactive segmentation. A study was performed in postpartum dairy cows (N=151), as an animal model of human fatty liver disease, to test this hypothesis. Five transcutaneous and five intraoperative US liver images were acquired in each animal and a liverbiopsy was taken. In liver tissue samples, triacylglycerol (TAG) was measured by biochemical analysis and hepatic diseases other than hepatic lipidosis were excluded by histopathologic examination. Ultrasonic tissue characterization (UTC) parameters--Mean echo level, standard deviation (SD) of echo level, signal-to-noise ratio (SNR), residual attenuation coefficient (ResAtt) and axial and lateral speckle size--were derived using a computer-aided US (CAUS) protocol and software package. First, the liver tissue was interactively segmented by two observers. With increasing fat content, fewer hepatic vessels were visible in the ultrasound images and, therefore, a smaller proportion of the liver needed to be excluded from these images. Automatic-segmentation algorithms were implemented and it was investigated whether better results could be achieved than with the subjective and time-consuming interactive-segmentation procedure. The automatic-segmentation algorithms were based on both fixed and adaptive thresholding techniques in combination with a 'speckle'-shaped moving-window exclusion technique. All data were analyzed with and without postprocessing as contained in CAUS and with different automated-segmentation techniques. This enabled us to study the effect of the applied postprocessing steps on single and multiple linear regressions ofthe various UTC parameters with TAG. Improved correlations for all US parameters were found by using automatic-segmentation techniques. Stepwise multiple linear-regression formulas where derived and used to predict TAG level in the liver. Receiver-operating-characteristics (ROC) analysis was applied to assess the performance and area under the curve (AUC) of predicting TAG and to compare the sensitivity and specificity of the methods. Best speckle-size estimates and overall performance (R2 = 0.71, AUC = 0.94) were achieved by using an SNR-based adaptive automatic-segmentation method (used TAG threshold: 50 mg/g liver wet weight). Automatic segmentation is thus feasible and profitable.

Abdominal circumference should not be a required criterion for the diagnosis of metabolic syndrome

BACKGROUND

Metabolic syndrome (MetS) is an established concept. However, it is characterized by a number of different definitions as well as different cut-off points (COPs) for waist circumference (WC) and different modes for incorporating WC into the diagnostic criteria.

METHODS

Abdominal ultrasonography was performed in 2,333 subjects who also underwent comprehensive medical examinations between April and July 2006. The odds ratios for the number of MetS components were calculated by taking central obesity status into account and considering concurrent fatty liver as an independent variable. We compared the areas under the receiver operating characteristic (ROC) curves for fatty liver and MetS using several MetS criteria.

RESULTS

Regardless of the WC criterion selected, we observed a strong linear trend for an association (trend P < 0.0001) between MetS and the number of components. The odds ratio (OR) of subjects without central obesity but with all three MetS components was 9.69 (95% confidence interval 3.11-30.2) in men and 55.3 (6.34-483) in women. The COP for the largest area under the curve in men and women was ≥82 cm (OR 0.701) and ≥77 cm (OR 0.699), respectively, when WC was considered as a component. When WC distribution is taken into consideration, practical and appropriate COPs should be ≥85 cm for men and ≥80 cm for women.

CONCLUSION

We suggest that a WC of ≥85 cm for men and ≥80 cm for women would be optimal COPs for the central obesity criteria in the Japanese population. In addition, central obesity should be incorporated as a component of MetS rather than an essential requirement for the diagnosis of MetS.

Methods for assessing intrahepatic fat content and steatosis

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Treatment of non-alcoholic fatty liver disease with metformin versus lifestyle intervention in insulin-resistant adolescents

The presence of fatty liver per ultrasound and liver-associated enzymes were measured in a select cohort of youth with both obesity and insulin resistance, and the effect of metformin on these parameters evaluated. Fifty obese, multiethnic, insulin-resistant adolescents (mean age 15.1 yr, mean body mass index 39.8 kg/m2) were randomized to receive lifestyle recommendations plus either twice per day doses of 850 mg of metformin or placebo. Fasting and post-glucose challenge biochemistries and liver ultrasounds were compared at baseline and 6 months. The prevalence of fatty liver was 74%, elevated alanine aminotransferase (ALT) 14%, aspartate aminotransferase (AST) 14%, and gamma-glutamyl transferase (GGT) 17%. Fatty liver was mild in 23%, moderate in 31%, and severe in 46%. Fatty liver was more common in male and Hispanic subjects and elevated ALT more common in Hispanic subjects. Subjects with fatty liver appeared more insulin resistant (higher fasting insulin and triglycerides, lower high-density lipoprotein cholesterol) and had higher ALT and AST. At 6 months, mean ALT, GGT, and fasting insulin improved significantly in all subjects. Fatty liver prevalence (p < 0.04), severity (p < 0.04), and fasting insulin (p < 0.025) improved significantly with metformin compared to placebo. Non-alcoholic fatty liver disease (NAFLD) occurs with a high prevalence and severity in obese, insulin-resistant adolescents. While metformin plus lifestyle intervention appears promising, defining NAFLD therapies capable of preventing fibrosis and cirrhosis requires further study.

Non-invasive means of measuring hepatic fat content

Hepatic steatosis affects 20% to 30% of the general adult population in the western world. Currently, the technique of choice for determining hepatic fat deposition and the stage of fibrosis is liver biopsy. However, it is an invasive procedure and its use is limited, particularly in children. It may also be subject to sampling error. Non-invasive techniques such as ultrasound, Computerized tomography (CT), magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (¹H MRS) can detect hepatic steatosis, but currently cannot distinguish between simple steatosis and steatohepatitis, or stage the degree of fibrosis accurately. Ultrasound is widely used to detect hepatic steatosis, but its sensitivity is reduced in the morbidly obese and also in those with small amounts of fatty infiltration. It has been used to grade hepatic fat content, but this is subjective. CT can detect hepatic steatosis, but exposes subjects to ionizing radiation, thus limiting its use in longitudinal studies and in children. Recently, magnetic resonance (MR) techniques using chemical shift imaging have provided a quantitative assessment of the degree of hepatic fatty infiltration, which correlates well with liver biopsy results in the same patients. Similarly, in vivo¹H MRS is a fast, safe, non-invasive method for the quantification of intrahepatocellular lipid (IHCL) levels. Both techniques will be useful tools in future longitudinal clinical studies, either in examining the natural history of conditions causing hepatic steatosis (e.g. non-alcoholic fatty liver disease), or in testing new treatments for these conditions.

The accuracy of sonography in predicting steatosis and fibrosis in chronic hepatitis C

The accuracy and clinical significance of sonography (US) in demonstrating fatty liver and hepatic fibrosis in chronic hepatitis C (CHC) are rarely reported. US had sensitivity 71.1%, specificity 72.9%, 58.7% positive predictive value (PPV), and 82.3% negative predictive value (NPV) in demonstrating histological steatosis > or =5%. US had sensitivity 85.7%, specificity 60.4%, 13% PPV, and 98.4% NPV in demonstrating histological steatosis > or =30% with clinical significance in predicting prognosis and therapeutic response in CHC. Subjects with fatty liver on US had a greater prevalence of body mass index (BMI) > or =25 kg/m2, inflammation-necrosis grade >2, and total bilirubin <1.2 mg/dl in multivariate analyses. US had sensitivity 27.4%, specificity 62.5%, 71.9% PPV, and 19.7% NPV in demonstrating histological fibrosis of stage II or above, and sensitivity 13.6%, specificity 66.3%, 9.4% PPV, and 75.0% NPV in demonstrating fibrosis of stage III or above. There was no correlation between fibrotic sonographic patterns and histological stage of fibrosis (r = -0.167, P = 0.083). Besides hepatic steatosis, clinicians should be alert to the possibility of advanced necrosis-inflammation grade in interpreting a report of bright liver on gray-scale US. Gray-scale US cannot replace liver biopsy as the optimal diagnostic procedure for the prediction of hepatic steatosis and fibrosis prior to initiating therapy for CHC.

Computer-aided B-mode ultrasound diagnosis of hepatic steatosis: a feasibility study

Fatty liver (steatosis) occurs in obese patients, among others, and is related to the development of diabetes type-2. Timely diagnosis of steatosis is therefore of great importance. Steatosis is also the most common liver disease of high-yielding dairy cattle during early lactation. This makes it a suitable animal model for studying liver steatosis. Furthermore, reference of derived ultrasound parameters against a "gold standard" is possible in cattle by taking a liver biopsy for the assessment of fat concentration. The authors undertook this pilot study to investigate the hypothesis that quantitative, computer-aided B-mode ultrasound enables the noninvasive detection of hepatic steatosis. Echographic images were obtained postpartum from dairy cows (n = 12) in transcutaneous and direct (intraoperative) applications using a convex array transducer at 4.2 MHz. During surgery, a biopsy was taken from the caudate lobe to assess the liver fat content (fat score). A custom-designed software package for computer-aided ultrasound diagnosis (CAUS) was developed. After linearizing the post-processing look-up-table (LUT), the image gray levels were transferred into echo levels in decibels relative to the mean echo level in a tissue-mimicking phantom. The quantitative comparison of transcutaneous and intraoperative images enabled the correction for the attenuation effect of skin and subcutaneous fat layer on the mean echo level in the liver, as well as for the effects of the beam formation and attenuation of liver tissue on the echo level vs. depth. The residual attenuation coefficient (dB/cm) in fatty liver vs. normal liver was estimated and compensated for. Finally, echo level was estimated relative to the phantom used for calibration, and echo texture was characterized by the mean axial and lateral speckle size within the regions of interest. In the no fat/low fat group (n = 5) skin plus fat layer attenuation was 3.4 dB/cm. A correlation of skin layer thickness vs. fat score of r = 0.48 was found. The mean transcutaneous liver tissue echo level correlated well with fat score: r = 0.80. A residual liver attenuation coefficient of 0.76 dB/cm and 1.19 dB/cm was found in medium and high fat liver, respectively. In transcutaneous images, correlation of residual attenuation coefficient with fat score was r = 0.69. Axial and lateral speckle sizes were on the order of 0.2 and 1.0 cm, respectively, and no correlation was found with liver fat content. Results for transcutaneous and intraoperative images were similar. The authors conclude that this pilot study shows the feasibility of calibrated, computer-aided ultrasound for noninvasively diagnosing, possibly even screening, steatosis of the liver.

Hepatic lipid accumulation in healthy subjects: a comparative study using spectral fat-selective MRI and volume-localized 1H-MR spectroscopy

Fat-selective MRI was applied to assess the amount and spatial distribution of hepatic lipids (HL) in healthy subjects. The results were compared with those obtained by localized 1H-MR spectroscopy (MRS). Ninety subjects (23-63 years old) underwent single-slice fat-selective MRI with spatial-spectral excitation and volume-localized spectroscopy at 1.5 T. HLs were analyzed in ventral and dorsal regions of interest (ROIs) of the liver in fat-selective images. Spectra were evaluated using the integral signal of methylene and methyl signals. The fat-selective images showed smooth and homogeneous distribution of HL over the entire cross section of the liver. There was, however, a marked interindividual variability in the amount of HL. MRS revealed a lipid signal fraction between 0.5% and 39.3%. The fat content in the ROIs in images correlated well with the spectroscopic results (r >or= 0.95). Both techniques provide sufficient sensitivity for a reliable and quantitative assessment of liver steatosis in subjects without liver disease. 1H-MRS has a higher sensitivity compared to MRI, especially for small amounts of HL, which may be of interest for metabolic interventions. Fat-selective images provide more spatial information about fat distribution, which makes this technique suitable for clinical imaging of patients with liver disease.

Correlation of ultrasound attenuation and histopathological parameters of the liver in chronic diffuse liver diseases

OBJECTIVE

In patients with chronic diffuse liver diseases two characteristic ultrasound patterns of bright liver, the low (DI) and the high (DII) attenuation types, are seen. Correlation was studied between liver attenuation and histopathological analysis of biopsy specimens of the same patients.

METHODS

Ultrasound attenuation of the liver was measured quantitatively using a homogeneous tissue-equivalent reference phantom. Semiquantitative scores were used for histopathological analysis of biopsy specimens.

RESULTS

One hundred and twenty-two patients were investigated; 40 of them showed a normal liver echopattern. The average attenuation was 0.68+/-0.03 dB/cm per MHz. Histopathological parameters were normal in most of the patients, except for four cases where a minimal amount of collagen and 14 cases where a subtle amount of lipid content could be detected, in three cases accompanied by some cells indicating inflammation. From 82 patients with bright liver, 47 showed the DI type. The average attenuation was 0.80+/-0.03 dB/cm per MHz. In all of these patients, significant increases of collagen content and inflammatory reaction were found. In 23 cases a negligible amount of lipid deposition could also be revealed. Thirty-five patients exhibited a DII-type bright liver. The average attenuation was 1.21+/-0.06 dB/cm per MHz. A significant amount of lipid deposition was detected in all cases. In 13 patients a minimal amount of collagen and in 14 patients some inflammatory cells were detected.

CONCLUSIONS

In livers with a normal echopattern, none or minimal pathological changes were seen. In DI-type bright liver, connective tissue dominance exists, in DII-type bright liver lipid deposition dominance. On this basis it is proved that the diagnosis of a fatty liver can be established without biopsy, if no other indication for biopsy exists.

Hepatobiliary manifestations of cystic fibrosis in children: correlation of CT and US findings

MATERIAL AND METHODS

Abdominal US and CT scans of 50 pediatric cystic fibrosis (CF) patients were evaluated to search for specific data that can be attributed to the involvement of the hepatobiliary system. The liver findings of the two patients who were HBs antigen carriers were excluded from the study.

RESULTS

30 out of 48 patients had at least one abnormal finding of liver on CT and/or US. Although increased echogenicity of the liver was detected in 24 of 48 patients (50%), only six of these (12%) were regarded as steatosis according to CT criteria of low attenuation values. CT and US scans both showed unique multilobular fatty pattern, described as "pseudomasses" in three patients. Increased periportal echogenicity was seen in 18 (37%) patients on US, while CT could not demonstrate any sign of increased periportal thickness. Findings of cirrhosis were present in five patients with either modalities. Lymph nodes of less than 10-15 mm in diameter were detected at the hepatico-duodenal ligament in 18 (37%) patients. Anomalies of the gallbladder (absence or microgallbladder or stone) were detected in 12 cases (24%).

CONCLUSION

Although US is the most widely used modality in CF patients, CT and US correlation will help to better delineate the abnormalities between steatosis and periportal fibrosis and increase the sensitivity of the imaging methods to achieve the most accurate diagnosis.

The effects of pantethine on fatty liver and fat distribution

Although the prognosis of fatty liver depends on its causes, we feel from our clinical experience that fatty liver with hypertriglyceridemia has a good prognosis and responds well to treatment. In this study, 600 mg/day of pantethine was administered to 16 outpatients with fatty liver and hypertriglyceridemia for six months or longer to examine whether the drug improved fatty liver using abdominal plain computed tomography (CT). Nine of the 16-pantethine patients were no longer diagnosed as having fatty liver after the study period. An chi2 test indicated the significant disappearance of fatty liver. At the same time, the visceral fat calculated from the CT image passing the umbilical region was also significantly reduced. On the contrary, the subcutaneous fat area tended to increase, so the ratio of the visceral-to-subcutaneous fat area was reduced significantly. This indicates triglycerides may be pooled in the body as hepato-visceral fat and subcutaneous fat, and that pantethine may transfer fat from the liver and viscera to the subcutaneous tissue. This suggests that visceral fat deposition and fatty liver occurring with hypertriglyceridemia may have a common basis, probably excessive matrixes, and that pantethine may simultaneously improve the two conditions.

Comparative evaluation of fatty infiltration of the liver in dairy cattle by using blood and serum analysis, ultrasonography, and digital analysis

Blood samples were collected from 158 Holstein-Friesian cows and analysed for aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transferase and ornithine carabamoyltransferase activities and glucose, total bilirubin, triglyceride, cholesterol-ester and non-esterified fatty acids concentrations. Ultrasonography of the liver was performed, and hepatic ultrasonograms were evaluated subjectively or analysed digitally, and liver samples were examined histopathologically. The diagnostic rates for the different tests were compared. Of the 158 animals, 117 had a normal liver and 41 had fatty infiltration of the liver. For diagnosis of fatty infiltration, digital analysis had the highest sensitivity, specificity, accuracy, and positive and negative predictive values, followed by ultrasonography.