Noninvasive in vivo quantitative assessment of fat content in human liver

Colorectal cancer: texture analysis of portal phase hepatic CT images as a potential marker of survival

PURPOSE

To assess the utility of texture analysis of liver computed tomographic (CT) images by determining the effect of acquisition parameters on texture and by comparing the abilities of texture analysis and hepatic perfusion CT to help predict survival for patients with colorectal cancer.

MATERIALS AND METHODS

The study comprised a phantom test and a clinical evaluation of 48 patients with colorectal cancer who had consented to retrospective analysis of hepatic perfusion CT data acquired during a research study approved by the institutional review board. Both components involved texture analysis to quantify the relative contribution of CT features between 2 and 12 pixels wide to overall image brightness and uniformity. The effect of acquisition factors on texture was assessed on CT images of a cylindric phantom filled with water obtained by using tube currents between 100 and 250 mAs and voltages between 80 and 140 kVp. Texture on apparently normal portal phase CT images of the liver and hepatic perfusion parameters were related to patient survival by using Kaplan-Meier survival analysis.

RESULTS

A texture parameter that compared the uniformity of distribution of CT image features 10 and 12 pixels wide exhibited the least variability with CT acquisition parameters (maximum coefficient of variation, 2.6%) and was the best predictor of patient survival (P < .005). There was no significant association between survival and hepatic perfusion parameters.

CONCLUSION

The study provides preliminary evidence that analysis of liver texture on portal phase CT images is potentially a superior predictor of survival for patients with colorectal cancer than CT perfusion imaging.

SUPPLEMENTAL MATERIAL

http://radiology.rsnajnls.org/cgi/content/full/2502071879/DC1.

Quantification of liver fat content: comparison of triple-echo chemical shift gradient-echo imaging and in vivo proton MR spectroscopy

PURPOSE

To validate a triple-echo gradient-echo sequence for measuring the fat content of the liver, by using hydrogen 1((1)H) magnetic resonance (MR) spectroscopy as the reference standard.

MATERIALS AND METHODS

This prospective study was approved by the appropriate ethics committee, and written informed consent was obtained from all patients. In 37 patients with type 2 diabetes (31 men, six women; mean age, 56 years), 3.0-T single-voxel point-resolved (1)H MR spectroscopy of the liver (Couinaud segment VII) was performed to calculate the liver fat fraction from the water (4.7 ppm) and methylene (1.3 ppm) peaks, corrected for T1 and T2 decay. Liver fat fraction was also computed from triple-echo (consecutive in-phase, opposed-phase, and in-phase echo times) breath-hold spoiled gradient-echo sequence (flip angle, 20 degrees), by estimating T2* and relative signal intensity loss between in- and opposed-phase values, corrected for T2* decay. Pearson correlation coefficient, Bland-Altman 95% limit of agreement, and Lin concordance coefficient were calculated.

RESULTS

Mean fat fractions calculated from the triple-echo sequence and (1)H MR spectroscopy were 10% (range, 0.7%-35.6%) and 9.7% (range, 0.2%-34.1%), respectively. Mean T2* time was 14.7 msec (range, 5.4-25.4 msec). Pearson correlation coefficient was 0.989 (P < .0001) and Lin concordance coefficient was 0.988 (P < .0001). With the Bland-Altman method, all data points were within the limits of agreement.

CONCLUSION

A breath-hold triple-echo gradient-echo sequence with a low flip angle and correction for T2* decay is accurate for quantifying fat in segment VII of the liver. Given its excellent correlation and concordance with (1)H MR spectroscopy, this triple-echo sequence could replace (1)H MR spectroscopy in longitudinal studies.

Liver fat, visceral adiposity, and sleep disturbances contribute to the development of insulin resistance and glucose intolerance in nondiabetic dialysis patients

Hemodialysis patients exhibit insulin resistance (IR) in target organs such as liver, muscles, and adipose tissue. The aim of this study was to identify contributors to IR and to develop a model for predicting glucose intolerance in nondiabetic hemodialysis patients. After a 2-h, 75-g oral glucose tolerance test (OGTT), 34 hemodialysis patients were divided into groups with normal (NGT) and impaired glucose tolerance (IGT). Indices of insulin sensitivity were derived from OGTT data. Measurements included liver and muscle fat infiltration and central adiposity by computed tomography scans, body composition by dual energy X-ray absorptiometer, sleep quality by full polysomnography, and functional capacity and quality of life (QoL) by a battery of exercise tests and questionnaires. Cut-off points, as well as sensitivity and specificity calculations were based on IR (insulin sensitivity index by Matsuda) using a receiver operator characteristics (ROC) curve analysis. Fifteen patients were assigned to the IGT, and 19 subjects to the NGT group. Intrahepatic fat content and visceral adiposity were significantly higher in the IGT group. IR indices strongly correlated with sleep disturbances, visceral adiposity, functional capacity, and QoL. Visceral adiposity, O2 desaturation during sleep, intrahepatic fat content, and QoL score fitted into the model for predicting glucose intolerance. A ROC curve analysis identified an intrahepatic fat content of >3.97% (sensitivity, 100; specificity, 35.7) as the best cutoff point for predicting IR. Visceral and intrahepatic fat content, as well as QoL and sleep seemed to be involved at some point in the development of glucose intolerance in hemodialysis patients. Means of reducing fat depots in the liver and splachnic area might prove promising in combating IR and cardiovascular risk in hemodialysis patients.

Efficacy of atorvastatin for the treatment of nonalcoholic steatohepatitis with dyslipidemia

Nonalcoholic steatohepatitis (NASH) is the hepatic manifestation of the metabolic syndrome. Currently, there is no established therapy for NASH. The aim of the present study was to evaluate the efficacy of atorvastatin in the treatment of NASH associated with hyperlipidemia. This prospective study included 31 patients with biopsy-proven NASH with hyperlipidemia. Body mass index, serum lipids, liver function tests, fibrosis markers, and adipocytokines (adiponectin, leptin, tumor necrosis factor-alpha) were measured periodically during an open-label study of atorvastatin (10 mg daily) for 24 months. Standard weight-loss counseling was continued during the treatment period. Oral glucose tolerance test and liver density assessed by computerized tomography were performed before and after treatment. Follow-up liver biopsy was performed in 17 patients. All 31 patients had high cholesterol levels at baseline, and 20 also presented high triglyceride levels. The body mass index and serum glucose levels did not change during the treatment. After treatment, 23 patients (74.2%) presented normal transaminase levels. Adiponectin levels were significantly increased, and the levels of tumor necrosis factor-alpha were significantly decreased. However, leptin levels were not changed significantly. The concentration of long-chain fatty acids was decreased; and significant decreases were observed in C18:2,n-6 (linoleic acid, -21%) and C20:4,n-6 (arachidonic acid, -22%). Liver steatosis and nonalcoholic fatty liver disease activity score were significantly improved, whereas 4 patients had increased fibrosis stage. The NASH-related metabolic parameters improved with therapy, including fibrosis in some patients. However, 4 of 17 patients had progression of fibrosis over the 2-year period, with 3 of them progressing to stage 3. It is unclear whether this divergent response represents sampling error, heterogeneity in the population, or untreated postprandial hyperglyceridemia. Controlled trials are needed to further investigate and resolve this.

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

PURPOSE

To evaluate in-phase and out-of-phase magnetic resonance (MR) imaging in the estimation of liver fat content (LFC) in patients with nonalcoholic fatty liver disease (NAFLD), with hydrogen ((1)H) MR spectroscopy as the reference standard.

MATERIALS AND METHODS

Written informed consent was obtained from all subjects, and the local ethics committee approved this prospective study protocol. A total of 33 patients with type 2 diabetes mellitus who were at high risk for NAFLD (23 men, 10 women; overall mean age, 62.8 years +/- 8.3 [standard deviation]; age range, 48-77 years) underwent 1.5-T MR imaging with (1)H MR spectroscopy and in-phase and out-of-phase imaging of the liver. Three fat indexes were calculated from the signal intensity (SI) measured on the images. Two radiologists independently graded SI changes between in-phase and out-of-phase images by means of visual inspection. The Pearson correlation coefficient was used to study the relationship between the obtained parameters of SI change and LFC measured with (1)H MR spectroscopy.

RESULTS

Fat indexes calculated from in-phase and out-of-phase images correlated linearly with LFC measured with (1)H MR spectroscopy (P < .001, r = 0.94-0.96) and were superior (P = .004) to visual estimates (P < .001, r = 0.88). The simple difference in SI between in-phase and out-of-phase images was used to calculate the fat index. An intercept of the regression line with the x-axis was observed at 5.1%, discriminating between normal and elevated LFC with high sensitivity (95%) and specificity (98%).

CONCLUSION

In-phase and out-of-phase imaging can be used to rapidly estimate the LFC in patients with NAFLD. The cutoff value of 5.1% enables objective rapid and reliable discrimination of normal LFC from elevated LFC.

Effect of endurance exercise on hepatic lipid content, enzymes, and adiposity in men and women

Obesity and physical inactivity are independent risk factors for the development of nonalcoholic fatty liver disease (NAFLD). We determined the effect of endurance exercise training on hepatic lipid content and hepatic enzyme concentration in men and women. Waist circumference (WC), percent body fat (BF), computed tomography (CT) scans for liver attenuation (inverse relationship with hepatic lipid), bilirubin, alanine aminotransferase (ALT), and gamma-glutamyltransferase (GGT) plasma concentrations were measured before and after 12 weeks of endurance training in 41 lean and obese men and women. Exercise training did not change liver attenuation, body weight, percent BF, bilirubin, or ALT concentration, but did lower WC (P < 0.0001), and decreased GGT in men only (P = 0.01). Obese subjects had a lower liver attenuation than lean subjects (P = 0.04). Obese women had lower ALT than obese men (P = 0.03). GGT was lower in women before and after training. WC was positively correlated with GGT (r = 0.32, P = 0.003) and ALT (r = 0.320, P = 0.004) and negatively correlated with liver attenuation (r = -0.340, P = 0.03). Percent BF was negatively correlated with bilirubin (r = -0.374, P = 0.005). Liver attenuation was negatively correlated with ALT (r = -0.405, P = 0.003). Short-term endurance training without weight loss does not alter hepatic lipid content. There was a strong relationship between GGT/ALT and body composition (percent BF) as well as between ALT and hepatic lipid content.

Liver steatosis: investigation of opposed-phase T1-weighted liver MR signal intensity loss and visceral fat measurement as biomarkers

PURPOSE

To investigate if opposed-phase T1-weighted and fat-suppressed T2-weighted liver signal intensity (SI) loss and visceral fat measurement at magnetic resonance (MR) imaging and body mass index (BMI) are correlated with grade of liver steatosis in patients with nonalcoholic fatty liver disease (NAFLD) or hepatitis C virus (HCV) and human immunodeficiency virus (HIV)-related liver disease.

MATERIALS AND METHODS

Committee on Human Research approval and patient consent were obtained for this HIPAA-compliant study. Fifty-two patients (15 men, 37 women) with NAFLD (n = 29) or HCV and HIV-related liver disease (n = 23) underwent prospective contemporaneous MR imaging and liver biopsy. Liver SI loss was measured on opposed-phase T1-weighted and fat-suppressed T2-weighted MR images. Visceral fat area was measured at three levels on water-suppressed T1-weighted MR images (n = 44). Spearman rank correlation coefficients and recursive partitioning were used to examine correlations.

RESULTS

Histopathologic liver steatosis correlated well with liver SI loss on opposed-phase T1-weighted MR images (rho = 0.78), fat-suppressed T2-weighted MR images (rho = 0.75), and average visceral fat area (rho = 0.77) (all P < .01) but poorly with BMI (rho = 0.53, P < .01). Liver SI losses on opposed-phase T1-weighted MR imaging of less than 3%, at least 3% but less than 35%, at least 35% but less than 49%, and at least 49% corresponded to histopathologic steatosis grades of 0 (n = 16 of 17), 1 (n = 11 of 16), 2 (n = 7 of 13), and 3 (n = 5 of 6), respectively. A visceral fat area of greater than or equal to 73.8 cm(2) was associated with the presence of histopathologic steatosis in 41 of 44 patients.

CONCLUSION

Liver SI loss on opposed-phase T1-weighted MR images and visceral fat area may be used as biomarkers for the presence of liver steatosis and appear to be superior to BMI.

Automated separation of visceral and subcutaneous adiposity in in vivo microcomputed tomographies of mice

Reflecting its high resolution and contrast capabilities, microcomputed tomography (microCT) can provide an in vivo assessment of adiposity with excellent spatial specificity in the mouse. Herein, an automated algorithm that separates the total abdominal adiposity into visceral and subcutaneous compartments is detailed. This algorithm relies on Canny edge detection and mathematical morphological operations to automate the manual contouring process that is otherwise required to spatially delineate the different adipose deposits. The algorithm was tested and verified with microCT scans from 74 C57BL/6J mice that had a broad range of body weights and adiposity. Despite the heterogeneity within this sample of mice, the algorithm demonstrated a high degree of stability and robustness that did not necessitate changing of any of the initially set input variables. Comparisons of data between the automated and manual methods were in complete agreement (R (2) = 0.99). Compared to manual contouring, the increase in precision and accuracy, while decreasing processing time by at least an order of magnitude, suggests that this algorithm can be used effectively to separately assess the development of total, visceral, and subcutaneous adiposity. As an application of this method, preliminary data from adult mice suggest that a relative increase in either subcutaneous, visceral, or total fat negatively influences skeletal quantity and that fat infiltration in the liver is greatly increased by a high-fat diet.

Imaging techniques for assessing hepatic fat content in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), an emerging clinical entity with worldwide recognition, is today the most common cause of abnormal liver function tests among adults in the United States. In Mexico City, its prevalence has been reported by our group to be around 14%, but its incidence is higher in the hispanic population in the United States (hispanic population 45%, white population 33%, black population 24%). The main issues in the diagnosis, follow-up, and management of NAFLD are our limited understanding of its pathophysiology and the difficulties involved in developing a noninvasive diagnostic method. Several imaging techniques can detect fatty infiltration of the liver, each with its own advantages and disadvantages. Ultrasound is still in the first option for diagnosis, but its accuracy depends on the operator and the patient's features. Computed tomography can detect hepatic fat content, but only at a threshold of 30%, and it involves ionizing radiation. Magnetic resonance (MR) spectroscopy is probably the most accurate and fastest method of detecting fat, but it is expensive and the necessary software is still not easily available in most MRI units. MR elastography, a new technique to detect liver stiffness, has not been demonstrated to detect NAFLD, and is still undergoing research in patients with hepatitis and cirrhosis. In conclusion, all these imaging tools are limited in their ability to detect coexisting inflammation and fibrosis. In this review, we discuss the radiological techniques currently used to detect hepatic fat content.

Effect of 6-month calorie restriction and exercise on serum and liver lipids and markers of liver function

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) and its association with insulin resistance are increasingly recognized as major health burdens. The main objectives of this study were to assess the relation between liver lipid content and serum lipids, markers of liver function and inflammation in healthy overweight subjects, and to determine whether caloric restriction (CR) (which improves insulin resistance) reduces liver lipids in association with these same measures.

METHODS AND PROCEDURES

Forty-six white and black overweight men and women (BMI = 24.7-31.3 kg/m(2)) were randomized to "control (CO)" = 100% energy requirements; "CR" = 25%; "caloric restriction and increased structured exercise (CR+EX)"= 12.5% CR + 12.5% increase in energy expenditure through exercise; or "low-calorie diet (LCD)" = 15% weight loss by liquid diet followed by weight-maintenance, for 6 months. Liver lipid content was assessed by magnetic resonance spectroscopy (MRS) and computed tomography (CT). Lipid concentrations, markers of liver function (alanine aminotransferase (ALT), alkaline phosphatase (ALK)), and whole-body inflammation (tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP)) were measured in fasting blood.

RESULTS

At baseline, increased liver lipid content (by MRS) correlated (P < 0.05) with elevated fasting triglyceride (r = 0.52), ALT (r = 0.42), and hsCRP (r = 0.33) concentrations after adjusting for sex, race, and alcohol consumption. With CR, liver lipid content was significantly lowered by CR, CR+EX, and LCD (detected by MRS only). The reduction in liver lipid content, however, was not significantly correlated with the reduction in triglycerides (r = 0.26; P = 0.11) or with the changes in ALT, high-density lipoprotein (HDL)-cholesterol, or markers of whole-body inflammation.

DISCUSSION

CR may be beneficial for reducing liver lipid and lowering triglycerides in overweight subjects without known NAFLD.

Presence of the metabolic syndrome in obese adolescents predicts impaired glucose tolerance and nonalcoholic fatty liver disease

PURPOSE

To evaluate whether the presence of metabolic syndrome (MS) in obese adolescents is associated with other comorbidities of obesity

METHODS

A total of 85 obese teens (70% female and 30% male) with fasting insulin >25 microU/ml and family history of type 2 diabetes mellitus and/or acanthosis nigricans were studied. Mean age was 15.8 +/- 1.7 years and body mass index (BMI) was 39.3 +/- 6.6 kg/m(2). Of the subjects, 54% were Hispanic and 35% black, 5% white, 5% American Indian, and 1% Asian. Laboratory analysis included fasting lipids, glucose, gamma-glutamyl transpeptidase (GGT), and oral glucose tolerance testing. Additional liver transaminase levels were determined and liver ultrasound (US) was performed to evaluate the presence and severity of fatty liver.

RESULTS

All subjects met MS criteria for children for waist circumference, 49% for blood pressure, 54% for high-density lipoprotein, 54% for triglycerides, and 20% for impaired fasting glucose (IFG) or impaired glucose tolerance [IGT]). In all, 47 subjects had three or more MS criteria. BMI was no different between groups with and without MS. Subjects with three or more MS criteria were more likely to have IGT (p = .004), elevated alanine aminotransferase (p = .039), elevated GGT (p = .036), fatty liver on US (p < .001), and more severe fatty liver (p = .001).

CONCLUSIONS

Abnormal glucose regulation and evidence of nonalcoholic fatty liver disease (NAFLD) were more common in subjects meeting three criteria for MS than in those meeting fewer criteria. The identification of MS provides value to the primary care provider. Those patients meeting criteria for MS should be evaluated for glucose intolerance and NAFLD.

Nonalcoholic fatty liver disease in a district general hospital: clinical presentation and risk factors

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) affects one-fifth of the adult population and is currently the commonest liver problem in the western world. The prevalence of NAFLD is likely to rise over the coming decades in parallel to the obesity and diabetes epidemics. A retrospective study was undertaken in a UK. district general hospital (DGH) to determine the clinical and laboratory features of patients with NAFLD.

METHODS AND FINDINGS

A total of 48 patients with NAFLD were identified. Most (54%) were asymptomatic on presentation and 90% had an echogenic liver on ultrasonography (USS). Liver tests were elevated in the majority, but did not distinguish between simple steatosis and steatohepatitis. Having features of the metabolic syndrome and a low platelet count (P = 0.028) may help identify patients with advanced hepatic fibrosis.

CONCLUSIONS

NAFLD is common in the DGH and should be considered in all patients with metabolic risk factors. A liver biopsy should be considered in those with low platelets, type II diabetes mellitus, and the metabolic syndrome.

Hypoadiponectinemia plays a crucial role in the development of nonalcoholic fatty liver disease in patients with type 2 diabetes mellitus independent of visceral adipose tissue

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver injury. The spectrum of NAFLD is broad, extending from simple steatosis through nonalcoholic steatohepatitis (NASH). Insulin resistance has been found to increase the risk of NASH, and obesity, and decreased levels of adiponectin are important factors in determining the severity of insulin resistance. Recent evidence has indicated that hypoadiponectinemia is involved in hepatic steatosis and NASH.

METHODS

To investigate whether hypoadiponectinemia causes hepatic steatosis in type 2 diabetes mellitus (DM) patients independently of visceral adipose tissue, we measured the plasma adiponectin concentration, hepatic fat content based on the liver-to-spleen ratio (L/S ratio) according to computed tomography (CT) attenuation values, and the amount of visceral adipose tissue and subcutaneous adipose tissue by CT in 248 type 2 DM patients. We also investigated the relationship between the serum level of adiponectin and hepatic fibrosis.

RESULTS

Significant correlations were observed between the L/S ratios and aspartate aminotransferase, alanine aminotransferase, visceral adipose tissue, subcutaneous adipose tissue, and serum adiponectin values (r=0.300, p=0.0007), and there was a highly significant inverse correlation between the visceral adipose tissue values and the serum adiponectin levels (r=-0.327, p<0.0002). The subcutaneous adipose tissue values, however, were not correlated with the serum adiponectin levels. Multiple regression analysis was used to quantify the impact of measured variables on the L/S ratio. After adjustment for age, gender, and visceral adipose tissue, the serum adiponectin levels were still significantly correlated with the L/S ratios (p=0.0064). And there was a stepwise decrease in the serum adiponectin in parallel to the severity of hepatic fibrosis.

CONCLUSIONS

Hypoadiponectinemia is concluded to be involved in the etiology of hepatic steatosis independently of visceral adipose tissue content, and is considered to be an important factor in the progression of fibrosis; further studies will be necessary to elucidate the exact physiological role of adiponectin and its contribution to the progression of NASH.

Association between dietary fat intake, liver fat, and insulin sensitivity in sedentary, abdominally obese, older men

Whether dietary fat influences the interaction between liver fat, visceral adipose tissue (VAT), and metabolic risk is unclear. Thus, we sought to determine the independent associations between 1 and 10 d dietary fat intake, liver fat, and VAT on insulin sensitivity using a cross-sectional design. Liver fat score (LFS) was assessed by computed tomography and VAT by magnetic resonance imaging in 42 abdominally obese older men. Insulin sensitivity was measured by the hyperinsulinemic–euglycemic clamp technique. Diet composition was determined from self-recorded diet records for 1 and 10 d preceding the assessment of LFS. LFS was positively associated with the 10 d average fat and alcohol intake, but not with any 1 d average dietary variables. VAT (r = –0.36) and LFS (r = –0.32) were both negatively correlated with insulin sensitivity (p < 0.05). When LFS and VAT were entered in the same model, only VAT was an independent predictor of insulin sensitivity (p < 0.05). Control for the average 10 d alcohol consumption and fat intake improved the association between insulin sensitivity and LFS (from r = –0.32, p > 0.10 to r = –0.49, p < 0.05), but not VAT. In fact, after control for the 10 d dietary variables, both LFS and VAT were independent predictors of insulin sensitivity (p < 0.05). This was not true for any of the 1 d dietary intake variables. In conclusion, liver fat is associated with dietary fat intake and alcohol consumption over 10 d, but not 1 d. Furthermore, dietary habits may influence the relationship between liver fat and insulin sensitivity.

A case-control study of non-alcoholic fatty liver disease in breast cancer

BACKGROUND

Patients with breast cancer sometimes present with increased liver enzymes during follow-up period that may be consistent with hepatic steatosis. This effect known as non-alcoholic fatty liver disease may be associated with the malignancy itself, drugs or some other well-known risk factors that may induce steatosis. We studied the influences of primary disease and treatment on steatosis in patients with breast cancer.

MATERIALS AND METHODS

There were four groups of patients in our study. Group 1: 40 newly diagnosed, previously untreated breast cancer; Group 2: 45 cases of breast cancer treated with systemic therapy; Group 3: 40 cases of ovarian cancer; Group 4: 40 healthy women. Hepatic steatosis was evaluated by sonography by two radiologist, independently. We also evaluated major risk factors, biochemical findings, and influences of treatment on hepatic steatosis.

RESULTS

We detected steatosis in 63%, 72%, 77%, and 48% of patients in groups 1, 2, 3, and 4, respectively. There was a statistically significant difference only between groups 3 and 4 (P = 0.045). However, grade 2 and 3 steatosis were more frequent in breast cancer patients (group 1 and 2), compared with mild steatosis in ovarian cancer patients and healthy women. Although a good correlation was found between tamoxifen use and chemotherapy on development of non-alcoholic fatty liver disease, no association of hepatic steatosis with transaminase levels was found, which might be of help for earlier detection of steatosis. AST/ALT ratio was found to have no impact on the rate of hepatic steatosis, contrary to the literature.

CONCLUSION

Hepatic steatosis, excluding patients with grade 1 steatosis, which may be a normal variant, were more readily detected in patients with breast cancer. This effect was aggravated by use of tamoxifen, but not the chemotherapy. Non-alcoholic fatty liver disease in patients with breast cancer may be associated with the primary tumor itself or some well-known risk factors such as obesity, hyperlipidemia, and diabetes mellitus, which needs to be explored.

Development of hepatic steatosis after pancreatoduodenectomy

OBJECTIVE

To determine the effects of pancreatoduodenectomy on hepatic fat content, hepatic CT attenuation was evaluated after pancreatoduodenectomy.

CONCLUSION

Pancreatoduodenectomy had a significant influence on hepatic fat content and was associated with frequent occurrence of hepatic steatosis, which was easily recognized with CT.

Metabolic conditions of fatty liver in non-diabetic obese women

INTRODUCTION

Steatosis of the liver has a close association with metabolic conditions such as obesity, dyslipidemia and diabetes mellitus. We aimed to determine metabolic features of subjects with different degrees of ultrasonographic steatosis.

MATERIALS AND METHODS

One hundred and thirty non-diabetic obese women were investigated (average age 43.47+/-12.55 yr, range 18-77 yr). They were negative for hepatitis virus and had no history of alcohol usage and diabetes mellitus. All subjects had a complete work-up including clinical examination, anthropometric measurements, laboratory tests, and a routine liver ultrasonographic scanning. Steatosis was graded as absent, mild, moderate, and severe.

RESULTS

A progressive increase was observed in the body mass index (p<0.05), waist circumference (p<0.01), body fat percentage (p<0.05), fasting plasma glucose (p<0.01), triglyceride (p<0.05), alanine aminotransferase (p<0.01), and aspartate aminotransferase (p<0.05) levels as the severity of ultrasonographic fatty liver increased. Also, insulin resistance, which was calculated via homeostasis model assessment, metabolic syndrome, and the prevalence of high alanine aminotransferase levels increased significantly with the degree of the steatosis. On the other hand, hypertriglyceridemia was found to be the independent risk factor for the severity of the steatosis.

CONCLUSION

The present study suggests that liver steatosis may be considered with some metabolic risk factors and particularly in the presence of insulin resistance and metabolic syndrome.

In search of biologic correlates for liver texture on portal-phase CT

RATIONALE AND OBJECTIVES

The acceptance of computer-assisted diagnosis (CAD) in clinical practice has been constrained by the scarcity of identifiable biologic correlates for CAD-based image parameters. This study aims to identify biologic correlates for computed tomography (CT) liver texture in a series of patients with colorectal cancer.

MATERIALS AND METHODS

In 28 patients with colorectal cancer, total hepatic perfusion (THP), hepatic arterial perfusion, and hepatic portal perfusion (HPP) were measured using perfusion CT. Hepatic glucose use was also determined from positron emission tomography (PET) and expressed as standardized uptake value (SUV). A hepatic phosphorylation fraction index (HPFI) was determined from both SUV and THP. These physiologic parameters were correlated with CAD parameters namely hepatic densitometry, selective-scale, and relative-scale texture features in apparently normal areas of portal-phase hepatic CT.

RESULTS

For patients without liver metastases, a relative-scale texture parameter correlated inversely with SUV (r = -0.587, P = .007) and, positively with THP (r = 0.512, P = .021) and HPP (r = 0.451, P = .046). However, this relative texture parameter correlated most significantly with HPFI (r = -0.590, P = .006). For patients with liver metastases, although not significant an opposite trend was observed between these physiologic parameters and relative texture features (THP: r < -0.4, HPFI: r > 0.35).

CONCLUSION

Total hepatic blood flow and glucose metabolism are two distinct but related biologic correlates for liver texture on portal phase CT, providing a rationale for the use of hepatic texture analysis as a indicator for patients with colorectal cancer.

Adipose tissue distribution in relation to insulin resistance in type 2 diabetes mellitus

Insulin resistance (IR) is typically more severe in obese individuals with type 2 diabetes (T2DM) than in similarly obese non-diabetics but whether there are group differences in body composition and whether such differences contribute to the more severe IR of T2DM is uncertain. DEXA and regional CT imaging were conducted to assess adipose tissue (AT) distribution and fat content in liver and muscle in 67 participants with T2DM (F39/M28, age 60 +/- 7 yr, BMI 34 +/- 3 kg/m(2)) and in 35 similarly obese, non-DM volunteers (F20/M15, age 55 +/- 8 yr, BMI 33 +/- 2 kg/m(2)). A biopsy of subcutaneous abdominal AT was done to measure adipocyte size. A glucose clamp was performed at an insulin infusion of 80 mU x min(-1) x m(-2). There was more severe IR in T2DM (6.1 +/- 2.3 vs. 9.9 +/- 3.3 mg x min(-1) x kg FFM(-1); P < 0.01). Group comparisons of body composition parameters was performed after adjusting for the effect of age, gender, race, height and total fat mass (FM). T2DM was associated with less leg FM (-1.2 +/- 0.4 kg, P < 0.01), more trunk FM (+1.1 +/- 0.4 kg, P < 0.05), greater hepatic fat (P < 0.05), and more subfascial adipose tissue around skeletal muscle (P < 0.05). There was a significant group x sex interaction for VAT (P < 0.01), with greater VAT in women with T2DM (P < 0.01). Mean adipocyte size (AS) did not significantly differ across groups, and smaller AS was associated with increased leg FM, whereas larger AS was related to more trunk FM (both P < 0.05). Group differences in IR were less after adjusting for group differences in leg FM, trunk FM, and hepatic fat, but these adjustments only partially accounted for the greater severity of IR in T2DM. In summary, T2DM, compared with similarly obese nondiabetic men and women, is associated with less leg FM and greater trunk FM and hepatic fat.

Elevated levels of serum advanced glycation end products in patients with non-alcoholic steatohepatitis

BACKGROUND AND AIM

Advanced glycation end products (AGE), senescent macroprotein derivatives formed at an accelerated rate in diabetes, play important roles in the pathogenesis of diabetic vascular complications. Recently, AGE have also been found to be involved in insulin resistance. Although non-alcoholic steatohepatitis (NASH) is generally considered a hepatic manifestation of insulin resistance, there are no reports showing the link of AGE to NASH. The aim of this study was to evaluate the clinical significance of AGE in patients with NASH.

METHODS

Glyceraldehyde-derived AGE levels were assayed from serum obtained from 106 patients: 66 with NASH, 10 with simple steatosis, and 30 controls.

RESULTS

Serum glyceraldehyde-derived AGE levels (U/mL) were significantly elevated in NASH patients (9.78 +/- 3.73) compared with simple steatosis (7.17 +/- 2.28, P = 0.018) or healthy controls (6.96 +/- 2.36, P = 0.003). Moreover, these were inversely correlated with adiponectin, an adipocytokine with insulin-sensitizing and anti-inflammatory properties. In addition, immunohistochemistry of glyceraldehyde-derived AGE showed intense staining in the livers of NASH patients.

CONCLUSION

The present data suggest that the sustained increase of glyceraldehyde-derived AGE could at least in part contribute to the pathogenesis of NASH. The serum glyceraldehyde-derived AGE level may be a useful biomarker for discriminating NASH from simple steatosis.

Independent associations between liver fat, visceral adipose tissue, and metabolic risk factors in men

The independent associations between liver fat, visceral adipose tissue (AT), and metabolic risk factors are unclear. Although it has been reported that visceral AT is the strongest predictor of metabolic risk, liver fat has also been reported as a strong independent associate of a deleterious metabolic profile. We examined the independent associations between liver fat, visceral AT, and metabolic risk factors in a sample of 293 men varying widely in adiposity. Liver fat and abdominal AT were measured by computed tomography (CT). Univariate analysis revealed that liver fat was associated (p < 0.05) with triglycerides (TG), systolic blood pressure (SBP), and total cholesterol (TC), but not with glucose or high-density lipoprotein cholesterol (HDLC). Liver fat remained a significant correlate (p < 0.05) of TG and TC after control for age and subcutaneous AT or cardiorespiratory fitness (CRF), but not after adjustment for visceral AT alone. Conversely, visceral AT remained significantly associated with TG, SBP, glucose, HDLC (p < 0.01), and TC (p = 0.05) independent of liver fat, subcutaneous AT, CRF, and age. Both liver fat and visceral AT were associated with metabolic risk in men. However, when controlled for each other, visceral AT was the only independent associate of metabolic risk.

The expression of NAD(P)H:quinone oxidoreductase 1 is high in human adipose tissue, reduced by weight loss, and correlates with adiposity, insulin sensitivity, and markers of liver dysfunction

CONTEXT

We have previously identified nicotinamide adenine dinucleotide phosphate:quinone oxidoreductase 1 (NQO1), an enzyme involved in the protection against oxidative stress, as a gene predominantly expressed in human adipocytes. Studies in mice deficient in NQO1 activity suggest that NQO1 may also play an important role in metabolism.

OBJECTIVE

The aim of this study was to explore the expression and regulation of NQO1 in human adipose tissue (AT) and isolated adipocytes.

PATIENTS AND RESULTS

The high expression of NQO1 in adipocytes was verified in human adipocytes and AT by real-time PCR. DNA microarray analysis showed that NQO1 was expressed at higher levels in large compared with small adipocytes, isolated from the same fat biopsy. Furthermore, NQO1 mRNA levels were positively correlated with adipocyte size (n = 7; P < 0.002). During an 18-wk diet regime (n = 24; mean weight loss 27 kg), the NQO1 expression in human sc AT was down-regulated (P < 0.0001), and mRNA levels correlated with body mass index (P = 0.0005), sc, and total abdominal AT areas, as determined by computerized tomography (P < 0.0001, both) and metabolic parameters. NQO1 mRNA levels were also positively correlated with aspartate aminotransferase (P = 0.0028) and alanine aminotransferase (P = 0.0219), markers known to be associated with severity of hepatic steatosis.

CONCLUSIONS

NQO1 is highly expressed in human AT, particularly in large adipocytes. AT NQO1 expression is reduced during diet-induced weight loss, and the expression levels positively correlate with adiposity, glucose tolerance, and markers of liver dysfunction. Together, these findings indicate a role for NQO1 in the metabolic complications of human obesity.

NASH and the risk of cirrhosis and hepatocellular carcinoma in type 2 diabetes

The risk of chronic liver disease and liver-related mortality is increased in patients with type 2 diabetes mellitus. Several cohort studies have suggested a metabolic pathway from nonalcoholic fatty liver, nonalcoholic steatohepatitis, cryptogenic cirrhosis, and eventually hepatocellular carcinoma. Although cardiovascular risk remains the major cause for excess mortality in type 2 diabetes mellitus, the risk of progressive liver disease should no longer be underscored.

Diagnosis of hepatic steatosis and fibrosis by transient elastography in asymptomatic healthy individuals: a prospective study of living related potential liver donors

BACKGROUND

This prospective study aimed to assess the ability of transient elastography to identify histologic parameters, including steatosis, in asymptomatic healthy individuals such as potential liver donors, and to compare these findings with results in liver disease patients.

METHODS

Forty-seven patients with abnormal liver function and/or hepatitis symptoms and 80 living related potential liver donors were consecutively enrolled, and liver biopsy and a Fibroscan test were performed in each subject. Histologic parameters were evaluated according to METAVIR scale by a single pathologist.

RESULTS

In liver disease patients, stiffness was significantly correlated with fibrosis stage (Spearman correlation coefficient, 0.700; P < 0.001), and the optimal stiffness cutoff values for F >or= 2, F >or= 3, and F = 4 were 7.35, 8.85, and 15.1 kPa respectively. In potential liver donors, however, stiffness was not correlated with fibrosis (0.023; P = 0.851). In the latter group, the area under the receiver-operating characteristics curve was 0.70 (95% confidence interval, 0.58-0.81), and the optimal stiffness cutoff value was 4.00 for F >or= 2, which was lower than that in liver disease patients. Steatosis was not correlated with stiffness (0.088; P = 0.463) in potential liver donors.

CONCLUSIONS

Transient elastography has limited value for detecting steatosis in asymptomatic healthy individuals, and the cutoff value for fibrosis should be reevaluated in these subjects.

Comparison of CT methods for determining the fat content of the liver

OBJECTIVE

The purpose of this study was to assess which of a number of methods of measuring attenuation on CT scans is best for prediction of hepatic fat content.

MATERIALS AND METHODS

This retrospective study was approved by our institutional review board. Consecutively registered patients who underwent liver resection for metastatic disease formed the study group. Attenuation measurements were obtained from 12 regions of interest in the liver and three in the spleen on both unenhanced and portal phase contrast-enhanced preoperative hepatic CT images. Hepatic attenuation measurements were analyzed both with and without normalization with the spleen. Normalization included both differences and ratios between hepatic and splenic attenuation values. Pathologic fat content was graded semiquantitatively as a percentage of the nonneoplastic liver parenchyma of the resected specimen. Average attenuation values of the liver were compared with pathologic fat content, as were the differences and ratios between hepatic and splenic attenuation values. Linear regression analysis was conducted on a log-log scale.

RESULTS

Data on 88 patients were analyzed. On unenhanced and contrast-enhanced CT images, all associations between pathologic fat content and attenuation measurements were significant (p < 0.0001). All series of R2 values for unenhanced CT scans were much higher than those for contrast-enhanced CT scans. The R2 values of liver-only measurement were higher than those of hepatic values normalized with splenic values on both unenhanced (0.646-0.649 > 0.523, 0.565) and contrast-enhanced (0.516 > 0.242, 0.344) CT.

CONCLUSION

Measurement of attenuation of liver only on unenhanced CT scans is best for prediction of pathologic fat content.

Technology Insight: advances in liver imaging

The role of diagnostic imaging in the assessment of liver disease continues to gain in importance. The classic techniques used for liver imaging are ultrasonography, CT and MRI. In the past decade, there have been significant advances in all three techniques. In this article, we discuss the advances in ultrasonography, CT and MRI that have improved assessment of focal and diffuse liver disease, including the development of hardware, software, processing algorithms and procedural innovations.

Role of radiologic modalities in the management of non-alcoholic steatohepatitis

During the last decade, the role of radiologic modalities in management of patients who have fatty liver disease has expanded. Ultrasonography has been used as a noninvasive alternative to biopsy for monitoring patients who have hepatic steatosis, but MRI is more appealing than ultrasonography to denote minor changes in hepatic fat content. Distinguishing patients who have non-alcoholic steatohepatitis from steatosis alone has become of clinical importance; however, the differences are not apparent with any radiologic modalities. Several modalities have been developed to noninvasively and accurately quantify hepatic fat content and diagnose steatohepatitis. In the future, radiologic modalities might be used to monitor the natural history of the disease or evaluate therapeutic interventions in patients who have non-alcoholic fatty liver disease.

Serum butyrylcholinesterase is strongly associated with adiposity, the serum lipid profile and insulin resistance

OBJECTIVE

We investigated the association between the serum butyrylcholinesterase (BChE) activity and parameters of adiposity, insulin resistance and the serum lipid profile, including the serum levels of triglyceride (TG), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C) in Japanese patients with type 2 diabetes and non-diabetic subjects.

PATIENTS AND METHODS

A total of 259 Japanese subjects [171 patients with type 2 diabetes (age 60.4+/-11.9 years, BMI 25.0+/-4.4) and 88 non-diabetic subjects (age 54.2+/-15.0 years, BMI 25.8+/-4.7)] were enrolled in the study. To assess the hepatic fat content, the ratio of the CT attenuation value of the liver to that of the spleen (L/S ratio) was calculated.

RESULTS

Serum BChE activity was significantly correlated with various indices of adiposity, including the waist circumference, L/S ratio, visceral fat area (VFA), subcutaneous fat area (SFA) and BMI, and also with the TG, HDL-C, LDL-C and HOMA-R, in the entire subject population. Even after adjustment for five variables, namely, age, gender, HbA1c, CRP and serum ferritin (the serum levels of ferritin and CRP have been reported to be associated with adiposity and insulin resistance), the serum BChE activity was still correlated with the waist circumference, L/S ratio, VFA, SFA, BMI, TG, HDL-C, LDL-C and HOMA-R. Furthermore, changes in the serum BChE activity were associated with changes in the L/S ratio, VFA and SFA at 1 year after the baseline.

CONCLUSIONS

These results indicate that the serum BChE activity is associated with parameters of adiposity, the serum lipid profile and the degree of insulin resistance.

Imaging of hepatic steatosis and fatty sparing

Radiology has gained importance in the non-invasive diagnosis of hepatic steatosis. Ultrasonography is usually the first imaging modality for the evaluation of hepatic steatosis. Unenhanced CT with or without dual kVp measurement and MRI with in and out of phase sequence can allow objective evaluation of hepatic steatosis. However, none of the imaging modalities can differentiate non-alcoholic steatohepatitis/fatty liver disease from simple steatosis. Evaluation of hepatic steatosis is important in donor evaluation before orthotopic liver transplantation and hepatic surgery. Recently, one-stop shop evaluation of potential liver donors has become possible by CT and MRI integrating vascular, parenchymal, volume and steatosis evaluation. Moreover hepatic steatosis (diffuse, multinodular, focal, subcortical, perilesional, intralesional, periportal and perivenular), hypersteatosis and sparing (geographic, nodular and perilesional or peritumoral) can cause diagnostic problems as a pseudotumor particularly in the evaluation of oncology patients. Liver MRI is used as a problem-solving tool in these patients. In this review, we discuss the current role of radiology in diagnosing, quantifying hepatic steatosis and solutions for diagnostic problems associated with fatty infiltration and sparing.

Alanine aminotransferase as a marker of non-alcoholic fatty liver disease in relation to type 2 diabetes mellitus and cardiovascular disease

For a long time, hepatic steatosis was believed to be a benign condition. Only recently, liver steatosis, also termed non-alcoholic fatty liver disease (NAFLD), has gained much interest. In most cases of NAFLD, a condition regarded as the hepatic component of the metabolic syndrome, the enzyme alanine aminotransferase (ALT) is elevated and consequently has been used as a marker for NAFLD. More recently, several cross-sectional and prospective studies have demonstrated associations of this liver enzyme with features of the metabolic syndrome and type 2 diabetes mellitus. This review discusses the biochemical and metabolic properties of ALT, its applicability as a marker of NAFLD and describes its possible role in the pathogenesis of the metabolic syndrome and type 2 diabetes mellitus and subsequent cardiovascular disease. In addition, treatment strategies to ameliorate NAFLD and the associated risks are discussed.

Fatty Liver: Imaging Patterns and Pitfalls

Fat accumulation is one of the most common abnormalities of the liver depicted on cross-sectional images. Common patterns include diffuse fat accumulation, diffuse fat accumulation with focal sparing, and focal fat accumulation in an otherwise normal liver. Unusual patterns that may cause diagnostic confusion by mimicking neoplastic, inflammatory, or vascular conditions include multinodular and perivascular accumulation. All of these patterns involve the heterogeneous or nonuniform distribution of fat. To help prevent diagnostic errors and guide appropriate work-up and management, radiologists should be aware of the different patterns of fat accumulation in the liver, especially as they are depicted at ultrasonography, computed tomography, and magnetic resonance imaging. In addition, knowledge of the risk factors and the pathophysiologic, histologic, and epidemiologic features of fat accumulation may be useful for avoiding diagnostic pitfalls and planning an appropriate work-up in difficult cases.

Influence of hepatic steatosis (fatty liver) on severity and composition of dyslipidemia in type 2 diabetes

OBJECTIVE

The objective of this study was to examine the associations between the severity of hepatic steatosis and dyslipidemia in type 2 diabetes, including circulating apolipoprotein B100 (apoB) concentrations and lipoprotein particle size and numbers.

RESEARCH DESIGN AND METHODS

Computed tomography imaging was used to assess hepatic fat content and adipose tissue distribution in 67 men and women with type 2 diabetes, withdrawn from antidiabetic medications preceding the study. Fasting serum lipoprotein number and size was determined by nuclear magnetic resonance. Insulin sensitivity was measured with a glucose clamp and a [6,6-(2)H(2)]glucose isotope infusion.

RESULTS

Two-thirds of the cohort had fatty liver. Hepatic steatosis correlated with serum triglycerides (r = 0.40, P < 0.01) and lower HDL cholesterol (r = -0.31, P < 0.05). ApoB and LDL cholesterol did not, being virtually identical in those with or without steatosis. The association between serum triglycerides and hepatic steatosis was largely accounted for by greater triglyceride enrichment in VLDL particles, which were larger. Severe steatosis was also associated with 70% higher small, dense LDL concentrations. Visceral obesity did not fully explain these associations, and hepatic steatosis was better correlated with triglycerides than with hyperglycemia or hepatic insulin resistance (P > 0.05).

CONCLUSIONS

The presence of hepatic steatosis in type 2 diabetes does not appear to affect apoB levels, but potentially increases atherogenesis by increasing triglycerides, reducing HDL levels, and increasing small, dense LDL.

Relationship between the serum concentrations of C-reactive protein and parameters of adiposity and insulin resistance in patients with type 2 diabetes mellitus

Serum C-reactive protein (CRP) concentrations have been reported to be associated with body fat, especially visceral fat accumulation, but most studies up to now have been conducted on non-diabetic subjects. In this study, we investigated the association between the serum CRP concentrations and parameters of adiposity and insulin resistance in both Japanese type 2 diabetes patients and non-diabetic subjects. A total of 248 Japanese subjects (140 type 2 diabetes patients and 108 non-diabetic subjects) were enrolled for the study. The degree of insulin resistance was estimated by the homeostasis model assessment (HOMA-R) method. Fat accumulation was evaluated by measuring visceral and subcutaneous fat areas at the level of the umbilicus in abdominal CT scans. To assess hepatic fat content, the ratio of CT attenuation value of the liver to that of the spleen (L/S ratio) was calculated. Serum CRP was found to be significantly correlated with various indices of adiposity, including L/S ratio, visceral fat area (VFA), subcutaneous fat area (SFA), and HOMA-R, in both the diabetic patients and the non-diabetic subjects. After adjustment for five variables (age, gender, serum CRP, HbA1c, and smoking), serum CRP was still significantly correlated with L/S ratio, VFA, SFA, and HOMA-R in the diabetic patients. We also found that changes in serum CRP concentrations were correlated with changes in the VFA and SFA at 1 year after the baseline in 24 diabetic patients. We conclude that serum CRP may be closely related to the degree of liver steatosis and visceral fat accumulation in Japanese type 2 diabetes mellitus patients.

Association of cardiorespiratory fitness, body mass index, and waist circumference to nonalcoholic fatty liver disease

BACKGROUND & AIMS

There is a need for more work examining the potential of physical activity and/or weight control as a preventive and/or therapeutic option in the treatment of fatty liver diseases. The purpose of this study was to examine the association between cardiorespiratory fitness, body mass index (BMI), and waist circumference with markers of nonalcoholic fatty liver disease (NAFLD).

METHODS

Participants consisted of 218 apparently healthy nonsmoking, nonalcoholic men aged 33-73 years. Cardiorespiratory fitness was assessed by a maximal treadmill test. Liver and spleen density were measured using a computed tomography scan. We defined the presence of NAFLD as the following 3 conditions being met: (1) liver to spleen density of 1.0 or less, (2) serum alanine transaminase level greater than 30 U/L, and (3) serum aspartate transaminase/alanine transaminase level less than 1.0.

RESULTS

Twenty-four (11%) of the participants met the NAFLD definition. There was an inverse association between fitness categories, and a positive association for BMI categories (and waist circumference categories) with the prevalence of NAFLD (P for trend <.001 for all). Fitness and BMI were independent of each other in their associations with the prevalence of NAFLD. The addition of waist circumference to the regression model attenuated the association with prevalence of NAFLD for both fitness (P value changed from <.0001 to .06) and BMI (P value changed from <.001 to .22).

CONCLUSIONS

Fitness (inversely) and BMI (directly) were associated with the prevalence of NAFLD. However, these associations were attenuated when abdominal obesity was included in the statistical model.

Evaluation of Living Liver Donors with an All-inclusive 3D Multi–Detector Row CT Protocol

PURPOSE

To prospectively assess parenchymal, vascular, and biliary anatomy of potential living liver donors with an all-inclusive multi-detector row computed tomographic (CT) approach.

MATERIALS AND METHODS

A total of 250 potential living liver donors (112 women, 138 men; mean age, 37 years) underwent three-phase, dual-enhancement multi-detector row CT to delineate biliary, vascular, and parenchymal morphology according to an institutional review board-approved protocol. Informed consent was obtained from all subjects. For display of the biliary system, the first CT image set was collected after the infusion of a biliary contrast agent. CT angiography was subsequently performed, after automated injection of a conventional iodinated contrast agent, to display the arterial and portal-hepatic venous systems. All data sets were reconstructed in 1-mm sections. Data analysis was based on source images, multiplanar reconstructions, and three-dimensional postprocessing images; was performed in consensus by two radiologists; and was focused on the detection of biliary and vascular variants, exclusion of focal liver lesions, and determination of hepatic volumes. Preoperative findings were correlated with intraoperative findings (available in 62 subjects).

RESULTS

Technical failures were experienced in 10 of 250 examinations. Twenty-seven subjects had moderate adverse reactions related to the biliary contrast agent. Benign hepatic lesions were detected in 61 candidates; one candidate had a renal cell carcinoma. Underlying biliary and vascular anatomy was displayed at least to the second intrahepatic branch in all but seven patients. Detected anatomic variants involved the biliary (38.8%), arterial (40.0%), portal venous (21.4%), and hepatic venous (43.5%) systems. Correlation with intraoperative findings was excellent. Some biliary (n = 4), arterial (n = 5), portal venous (n = 1), and hepatic venous (n = 6) variants were missed or misinterpreted at initial reading of preoperative data; however, variants could be retrospectively depicted in all but one biliary case and one hepatic venous case.

CONCLUSION

The outlined three-phase, dual-enhancement multi-detector row CT protocol represents an all-inclusive approach to evaluate potential living liver donors in a single diagnostic step.

Macrovesicular hepatic steatosis in living liver donors: use of CT for quantitative and qualitative assessment

PURPOSE

To determine prospectively the diagnostic performance of unenhanced computed tomography (CT) in the assessment of macrovesicular steatosis in potential donors for living donor liver transplantation by using same-day biopsy as a reference standard.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. A total of 154 candidates, including 104 men (mean age, 30.2 years +/- 10.3 [standard deviation]) and 50 women (mean age, 31.8 years +/- 11.2), underwent same-day unenhanced CT and ultrasonography-guided liver biopsy. Histologic degree of macrovesicular steatosis was determined. Three liver attenuation indices were derived: liver-to-spleen attenuation ratio (CT(L)(/S)), difference between hepatic and splenic attenuation (CT(L)(-S)), and blood-free hepatic parenchymal attenuation (CT(LP)). Regression equations were used to quantitatively estimate the degree of macrovesicular steatosis. Limits of agreement between estimated macrovesicular steatosis and the reference standard were calculated. Receiver operating characteristic analyses were used to determine the performance of each index for qualitative diagnosis of macrovesicular steatosis of 30% or greater. The cutoff value that provided a balance between sensitivity and specificity and the highest cutoff value that yielded 100% specificity were determined.

RESULTS

Limits of agreement were -14% to 14% for CT(L)(/S) and CT(L)(-S) and -13% to 13% for CT(LP). Performance in diagnosing macrovesicular steatosis of 30% or greater was not significantly different among indices (P > .05). Cutoff values of 0.9, -7, and 58 were determined for CT(L)(/S), CT(L)(-S), and CT(LP), respectively, and provided a balance between sensitivity and specificity. Cutoff values of 0.8, -9, and 42 were determined for CT(L)(/S), CT(L)(-S), and CT(LP), respectively, and yielded 100% specificity for all indices, with corresponding sensitivities of 82%, 82%, and 73% for CT(L)(/S), CT(L)(-S), and CT(LP), respectively.

CONCLUSION

Diagnostic performance of unenhanced CT for quantitative assessment of macrovesicular steatosis is not clinically acceptable. Unenhanced CT, however, provides high performance in qualitative diagnosis of macrovesicular steatosis of 30% or greater.

Visceral fat is an independent predictor of all-cause mortality in men

OBJECTIVE

To examine the independent associations of abdominal fat (visceral and subcutaneous) and liver fat with all-cause mortality.

RESEARCH METHODS AND PROCEDURES

Participants included 291 men [97 decedents and 194 controls; mean age, 56.4 +/- 12.0 (SD) years] who received a computed tomography (CT) examination at the preventive medicine clinic in Dallas, TX, between 1995 and 1999, with a mean mortality follow-up of 2.2 +/- 1.3 years. Abdominal fat was determined using contiguous CT images from the L3-L4 to L4-L5 intervertebral space. Liver fat was assessed using the CT-determined liver attenuation value, which is inversely related to liver fat. Logistic regression was used to determine the independent association between the fat depots and all-cause mortality.

RESULTS

During the study, there were 97 deaths. Visceral fat [odds ratio (OR) per SD: 1.83; 95% CI: 1.23 to 2.73], abdominal subcutaneous fat (1.44; 1.02 to 2.03), liver fat (0.64; 0.46 to 0.87), and waist circumference (1.41; 1.01 to 1.98) were significant individual predictors of mortality after controlling for age and length of follow-up. In a model including all three fat measures (subcutaneous, visceral, and liver fat), age, and length of follow-up, only visceral fat (1.93; 1.15 to 3.23) was a significant predictor of mortality.

DISCUSSION

Visceral fat is a strong, independent predictor of all-cause mortality in men.

Computed Tomography Features of Nonalcoholic Steatohepatitis With Histopathologic Correlation

OBJECTIVE

This study was conducted to describe the computed tomography (CT) features of nonalcoholic steatohepatitis (NASH) and to evaluate if the CT features could be used to diagnose and stage NASH.

METHODS

From 1994 until 2004, pathology records revealed 68 patients with NASH. Of these, 12 patients underwent CT scans before (n=6), on the same day as (n=3), or after (n=3) a liver biopsy. Using the same database, 9 patients with steatosis alone evaluated with a CT scan before (n=2), on the same day as (n=3), or after (n=4) the liver biopsy were selected as a control group. Two radiologists measured liver attenuation (compared with spleen) and assessed the pattern of steatosis, craniocaudal liver span, caudate-to-right lobe ratio, preportal space distance, and presence of porta hepatis lymph nodes and ascites. Biopsy specimens were assessed by a pathologist, and the degree of necroinflammatory activity, steatosis, and fibrosis was determined. Histopathologic and CT findings were compared between patients with NASH and patients with steatosis alone using the Mann-Whitney U test and Fisher exact test.

RESULTS

In patients with NASH, the mean liver-to-spleen attenuation ratio was 0.66 (range: 0.1-1.1). Steatosis was diffuse (n=9), geographic or nonlobar (n=2), or diffuse with an area of focal sparing (n=1). The liver craniocaudal span varied from 17.5 to 25.5 cm (mean=21.4 cm), and hepatomegaly was present in 11 (91.7%) patients. The caudate-to-right-lobe ratio (mean=0.43) and preportal space (mean=4.5 mm) were normal in all cases. Porta hepatis lymph nodes were present in 7 (58.3%) patients; their mean dimensions were 16 mmx11 mm. Ascites was absent in all patients. On histopathology, the degree of necroinflammatory activity was mild (n=9), moderate (n=1), or severe (n=2). The degree of steatosis was 33% to 66% (n=5) or >67% (n=7). All but 3 patients had fibrosis; 6 had focal nonbridging fibrosis, 1 had multifocal nonbridging fibrosis, and 2 had bridging fibrosis. There was a significant correlation between the degree of steatosis on pathologic examination and the liver-to-spleen attenuation ratio on CT (P=0.048). The severity of inflammation and stage of fibrosis on pathologic examination did not correlate with the CT features. Among patients with steatosis alone, the mean liver-to-spleen attenuation ratio was 0.80 (range: 0.3-1.2); the craniocaudal liver span varied from 12 to 20 cm (mean=16 cm); hepatomegaly was present in 2 (22.2%) patients; the caudate-to-right lobe ratio was normal in all patients, with a mean of 0.36 (range: 0.22-0.47); the preportal space distance was enlarged in 2 cases (mean=7.5 mm, range: 1-16 mm); porta hepatis lymph nodes were present in 7 (77.8%) patients, and their mean dimensions were 11 mmx8 mm (large axis range: 6-19 mm, short axis range: 4-14 mm); and no patient had ascites. There was a significant difference in the craniocaudal liver span between patients with NASH (mean=21 cm) and patients with steatosis (mean=16 cm) (P<0.05). The caudate-to-right-lobe ratio was also significantly different between patients with NASH (mean=0.43) and patients with steatosis (mean=0.36) (P<0.05). There were no significant differences in liver-to-spleen attenuation ratios, measurements of preportal space, or the presence of porta hepatic lymph nodes.

CONCLUSION

The CT features of NASH include steatosis, hepatomegaly, and porta hepatis lymph nodes, and the liver-to-spleen attenuation ratio correlated with the degree of steatosis on histopathology. Patients with NASH had a greater liver span and increased caudate-to-right-lobe-ratio compared with patients with steatosis alone.

Accuracy of liver fat quantification at MR imaging: comparison of out-of-phase gradient-echo and fat-saturated fast spin-echo techniques--initial experience

PURPOSE

To retrospectively determine the relative accuracy of liver fat quantification with out-of-phase gradient-echo magnetic resonance (MR) imaging and fat-saturated fast spin-echo MR imaging in patients with and without cirrhosis, with histologic analysis as the reference standard.

MATERIALS AND METHODS

Committee on Human Research approval was obtained. Patient consent was not required. Data collection ended before HIPAA regulations were implemented, but patient anonymity was maintained. Twenty-seven patients, 16 with cirrhosis, were retrospectively identified who underwent MR imaging before histopathologic evaluation of liver fat at biopsy or surgery. The patient population consisted of 15 male and 12 female patients (mean age, 55 years; range, 16-75 years). One radiologist blinded to the histopathologic results recorded mean signal intensity derived from three regions of interest placed in the right and left lobes of the liver on three sections and signal intensity of the spleen from one region of interest within the same section. Liver fat was quantified with the relative loss of signal intensity on out-of-phase images compared with that on in-phase T1-weighted gradient-echo images and with relative loss of signal intensity on T2-weighted fast spin-echo MR images obtained with fat saturation compared with those obtained without fat saturation. Hotelling t test was used to compare correlation coefficients between relative signal intensity differences and histopathologically determined percentage of fat.

RESULTS

In patients without cirrhosis, liver fat quantification with fat-saturated fast spin-echo MR imaging was significantly better than it was with out-of-phase gradient-echo MR imaging (r = 0.92 vs 0.69, P < .01). In patients with cirrhosis, liver fat quantification was correlated only with fat-saturated fast spin-echo MR imaging (r = 0.76, P < .01); the relative signal intensity loss on out-of-phase gradient-echo MR images was not correlated with histopathologically determined percentage of fat (r = 0.25, P = .36).

CONCLUSION

Preliminary results suggest liver fat may be more accurately quantified with fat-saturated fast spin-echo MR imaging than with out-of-phase gradient-echo MR imaging, especially in patients with cirrhosis.

Protocol for measurement of liver fat by computed tomography

To develop a protocol for measurement of liver fat using computed tomography (CT), we conducted a preliminary study with 118 men and 76 women to determine a readily identifiable vertebral landmark at which the CT image displayed both liver and spleen. Analysis of five landmarks revealed that the CT image obtained at the T12-L1 level simultaneously displayed the liver and spleen in 90% of the men and women. The T12-L1 protocol was cross-validated on a sample of 130 men and 113 women. In this sample, we also assessed the regional characteristics of liver and spleen tissue attenuation at the T12-L1 level by subdividing each image into quartiles from anterior to posterior, each of which were further divided into medial and lateral regions. A similar analysis was performed on images located 12 mm above and below T12-L1. The T12-L1 image displayed both liver and spleen in 92% (403 of 437) of the combined study sample. There was a significant (P<0.005) stepwise increase in attenuation values [Hounsfield units (HU)] from the inferior to superior image. Although some significant (P<0.05) differences were observed between the eight regions by comparison to the whole liver or spleen, the average magnitude of the difference was <2.0 HU for liver and <3.5 HU for spleen. Acquisition of a single CT image at the T12-L1 level is a practical and reliable method for routine measurement of liver fat in research and clinical settings.

Is adiponectin level a predictor of nonalcoholic fatty liver disease in nondiabetic male patients?

AIM

Adiponectin is a hepatic insulin sensitizer and also an inhibitor of tumor necrosis factor. We studied its levels in nondiabetic patients with nonalcoholic fatty liver disease (NAFLD) and compared with control group.

METHODS

Thirty-five patients who had elevated serum aminotransferase levels with bright liver and 34 healthy volunteers without liver disease were evaluated. Age, gender and body mass index (BMI) were recorded. Fasting plasma glucose, insulin, adiponectin, proinsulin and lipid profile were measured. A standard oral glucose tolerance test (OGTT) with insulin response was performed and the index of insulin resistance was calculated according to the homeostasis model assessment (HOMA) method.

RESULTS

According to the OGTT results, none of the participants had diabetes. Serum adiponectin levels were statistically significantly lower in patients with NAFLD than in control group (8.14+/-3.4 microg/mL vs 12.4+/-9.4 microg/mL, respectively, P<0.01). A statistically significant correlation was found between adiponectin and BMI (r : -0.33, P<0.01), HOMA (r : -0.26, P<0.05), proinsulin (r : -0.32, P<0.01), AST (r : -0.25, P<0.05), ALT (r : -0.26, P<0.05) or GGT (r : -0.22, P<0.05). In multiple regression analysis models, adiponectin levels were the only predictor of NAFLD in males, whereas in female group it was the BMI.

CONCLUSION

Low adiponectin level might be a predictor of NAFLD especially in male nondiabetics.

Imaging Features of Perivascular Fatty Infiltration of the Liver: Initial Observations

PURPOSE

To retrospectively identify and describe the imaging features that represent perivascular fatty infiltration of the liver.

MATERIALS AND METHODS

The institutional review board approved the study and waived informed consent. The study complied with the Health Insurance Portability and Accountability Act. Ten patients (seven women, three men; mean age, 78 years; range, 31-78 years) with fatty infiltration surrounding hepatic veins and/or portal tracts were retrospectively identified by searching the abdominal imaging teaching file of an academic hospital. The patients' medical records were reviewed by one author. Computed tomographic (CT), magnetic resonance (MR), and ultrasonographic (US) imaging studies were reviewed by three radiologists in consensus. Fatty infiltration of the liver on CT images was defined as absolute attenuation less than 40 HU without mass effect and, if unenhanced images were available, as relative attenuation at least 10 HU less than that of the spleen; on gradient-echo MR images, it was defined as signal loss on opposed-phase images compared with in-phase images; and on US images, it was defined as hyperechogenicity of liver relative to kidney, ultrasound beam attenuation, and poor visualization of intrahepatic structures. Perivascular fatty infiltration of the liver was defined as a clear predisposition to fat accumulation around hepatic veins and/or portal tracts. For multiphase CT images, the contrast-to-noise ratio was calculated for comparison of spared liver with fatty liver in each imaging phase.

RESULTS

Fatty infiltration surrounded hepatic veins in three, portal tracts in five, and both hepatic veins and portal tracts in two patients. Six of the 10 patients had alcoholic cirrhosis, two reported regular alcohol consumption (one of whom had acquired immunodeficiency syndrome and hepatitis B), one was positive for human immunodeficiency virus, and one had no risk factors for fatty infiltration of the liver. In three of the 10 patients, fatty infiltration was misdiagnosed as vascular or neoplastic disease on initial CT images but was correctly diagnosed on MR images.

CONCLUSION

Perivascular fatty infiltration of the liver has imaging features that allow its recognition.

Serum ferritin is associated with visceral fat area and subcutaneous fat area

OBJECTIVE

Until now, few clinical studies have reported on the association between the indexes of body fat distribution and serum ferritin, an indicator of body iron stores and a putative risk factor for insulin resistance. We investigated the association between serum ferritin concentrations and the indexes of distribution of adipose tissues in the body, such as the visceral fat area (VFA), the subcutaneous fat area (SFA), and the hepatic fat content in Japanese subjects.

RESEARCH DESIGN AND METHODS

A total of 248 Japanese subjects (127 men and 121 postmenopausal women aged 57.8 +/- 13.9 years, BMI 25.7 +/- 4.6 kg/m2; 140 subjects with type 2 diabetes and 108 nondiabetic subjects) were evaluated. Subjects with a history of alcohol intake were excluded from the study. We measured body height, body weight, and serum ferritin, as well as fasting plasma glucose and plasma insulin concentrations. We estimated insulin resistance by homeostasis model assessment. The fat distribution was evaluated by measuring the VFA and SFA by abdominal computed tomography at the umbilical level. To assess the hepatic fat content, the ratio of the computed tomography attenuation value of the liver to that of the spleen was calculated.

RESULTS

Serum ferritin was significantly correlated with the various indexes of adiposity examined, such as the hepatic fat content (r = -0.280, P < 0.0001), VFA (r = 0.254, P < 0.0001), SFA (r = 0.231, P = 0.0005), and homeostasis model assessment (r = 0.286, P = 0.0008).

CONCLUSIONS

This is the first report to directly demonstrate an association between serum ferritin and VFA and SFA. The results of this study suggest that the serum ferritin concentration may be a useful indicator of systemic fat content and degree of insulin resistance.

Severity of ultrasonographic liver steatosis and metabolic syndrome in Korean men and women

AIM: To evaluate the association between the severity of liver steatosis and metabolic syndrome in apparently healthy Korean adults.

METHODS: We examined 1 022 men and women, aged 30-79 years, who participated in a health screening test. A standard interview, anthropometrics, biochemical studies, and abdominal ultrasonography were conducted for each participant. Metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel III, with a modification for the waist circumference cut-off level. The severity of liver steatosis was evaluated using liver ultrasonography, and serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and γ-glutamyl transferase (γ-GT) levels were determined.

RESULTS: Ultrasonographic liver steatosis was strongly associated with metabolic syndrome and common metabolic abnormalities. Compared with people without steatosis, people with mild, moderate, and severe steatosis had adjusted odds ratios for metabolic syndrome of 1.72 (95%CI, 1.01-2.94), 2.89 (1.75-4.76) and 3.53 (1.25-9.98) in men, and 2.86 (1.64-5.01), 3.19 (1.80-5.65) and 3.70 (0.82-16.73) in women, respectively. The serum AST level was not associated with metabolic syndrome. The serum ALT and γ-GT levels were significantly associated with metabolic syndrome in men but not in women.

CONCLUSION: The occurrence of metabolic syndrome shows a stronger association with the severity of ultrasonographic steatosis than with the serum liver enzyme levels. The degree of fatty infiltration detected on ultrasonography can be used as an indicator of liver dysfunction attributable to metabolic abnormalities.