In vitro chronic hepatic disease characterization with a multiparametric ultrasonic approach

Prevalence and characteristics of MAFLD in Chinese adults aged 40 years or older: A community-based study

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) was recently proposed to be renamed metabolic dysfunction-associated fatty liver disease (MAFLD) with the diagnostic criteria revised. We investigated the similarities and differences in the prevalence and clinical characteristics of MAFLD and NAFLD in Chinese adults.

METHODS

A cross-sectional study of 9980 Chinese individuals aged 40 years or older was performed between 2011 and 2012 using randomized, stratified cluster sampling in Shanghai, China. A detailed questionnaire and the results of abdominal ultrasonography, a standardized 2-h 75-g oral glucose tolerance test and blood biochemical examinations were collected.

RESULTS

A total of 9927 subjects were included in this study. The prevalence of MAFLD (40.3%) was significantly higher than that of NAFLD (36.9%) (P < 0.05). MAFLD was highly prevalent in type 2 diabetes mellitus (T2DM) (53.8%), impaired fasting glucose (35.7%) and impaired glucose tolerance (40.9%). High risk of advanced fibrosis based on fibrosis-4 was highly prevalent (14.7%) in lean MAFLD with T2DM. Among 9927 subjects, 3481 (35.1%) fulfilled the diagnostic criteria for MAFLD and NAFLD (MAFLD+NAFLD+), 521 (5.2%) MAFLD+NAFLD-, and 181 (1.8%) MAFLD-NAFLD+. The MAFLD+NAFLD- group had more significant metabolic disorders than those in the MAFLD+NAFLD+ group (all P < 0.05). Among MAFLD-NAFLD+ subjects, 82.9% had metabolic disorders.

CONCLUSIONS

The new definition of MAFLD may better reflect the pathogenesis related to metabolism. Future research should focus on studying the natural history, pathogenesis and treatment effectivity of the overlap and non-overlap of NAFLD and MAFLD subjects.

Association between Chinese visceral adiposity index and metabolic-associated fatty liver disease in Chinese adults with type 2 diabetes mellitus

OBJECTIVE

The purpose of the study was to determine the correlation of the Chinese visceral adiposity index (CVAI) with metabolic-associated fatty liver disease (MAFLD) in Chinese adults with type 2 diabetes mellitus (T2DM).

MATERIALS/METHODS

In this cross-sectional study, data on sociodemographic characteristics, laboratory test results, coexisting diseases, and medical therapy were collected and analyzed. Multivariate logistic regression analyses were used to examine the correlation between CVAI and MAFLD. In order to investigate the correlation between CVAI on a continuous scale and MAFLD, a restricted cubic spline (RCS) was used.

RESULTS

A total of 679 participants were included in this study. There were 251 female participants and 428 male participants, with a median age of 55 years. In the multivariate logistic regression model, diastolic blood pressure, duration of diabetes, glycated hemoglobin, hemoglobin, alanine transaminase, aspartate aminotransferase, gamma -glutamyl transferase, albumin, blood urea nitrogen, total cholesterol, low-density lipoprotein cholesterol, statin use and metformin use were adjusted, and an evident increase in the odds ratios of MAFLD from the lowest to the highest CVAI quartile was found (P value for trend < 0.001). Moreover, the RCS curves revealed a positive correlation between CVAI and MAFLD.

CONCLUSIONS

The CVAI is positively correlated with MAFLD and may be an indicator with diagnostic value for MAFLD in clinical practice in type 2 diabetic patients.

Proteomic Analysis of Human Serum for Patients at Different Pathological Stages of Hepatic Fibrosis

Background

Hepatic fibrosis is a severe liver disease that has threatened human health for a long time. In order to undergo timely and adequate therapy, it is important for patients to obtain an accurate diagnosis of fibrosis. Laboratory inspection methods have been efficient in distinguishing between advanced hepatic fibrosis stages (F3, F4), but the identification of early stages of fibrosis has not been achieved. The development of proteomics may provide us with a new direction to identify the stages of fibrosis.

Methods

We established serum proteomic maps for patients with hepatic fibrosis at different stages and identified differential expression of proteins between fibrosis stages through ultra-high-performance liquid chromatography tandem mass spectrometry proteomic analysis.

Results

From the proteomic profiles of the serum of patients with different stages of liver fibrosis, a total of 1,338 proteins were identified. Among three early fibrosis stages (control, F1, and F2), 55 differential proteins were identified, but no proteins simultaneously exhibited differential expression between control, F1, and F2. Differential proteins were detected in the comparison between different fibrosis stages. Significant differences were found between advanced fibrosis stages (F2-vs.-F3 and F3-vs.-F4) through a series of statistical analysis, including hierarchical clustering, Gene Ontology (GO) functional annotation, Kyoto Encyclopedia of Genes and Genomes pathway, and protein-protein interaction network analysis. The differential proteins identified by GO annotation were associated with biological processes (mainly platelet degranulation and cell adhesion), molecular functions, and cellular components.

Conclusions

All potential biomarkers identified between the stages of fibrosis could be key points in determining the fibrosis staging. The differences between early stages may provide a useful reference in addressing the challenge of early fibrosis staging.

Diagnosis of liver fibrosis in patients with hepatitis B-related liver disease using ultrasound with wave-number domain attenuation coefficient

BACKGROUND/AIMS

The importance of identifying the stage of liver fibrosis has motivated the development of non-invasive methods. This study aimed to evaluate the applicability of ultrasound analysis involving the wave-number domain attenuation coefficient (W-Ac) in the non-invasive quantitative differentiation of liver fibrosis.

MATERIALS AND METHODS

This was a prospective study of inpatients with hepatitis B-related liver disease treated between October 2016 and January 2018. In ultrasound, the echo from the near-field liver tissue was selected as the reference signal. The W-Ac of liver tissues was based on the fast Fourier transform of the acquired post-beamforming radio frequency signals. These values were compared with fibrosis from biopsy METAVIR score results. A receiver operating characteristic (ROC) curve tested the W-Ac method.

RESULTS

A total of 46 patients were enrolled, including 27 males and 19 females. Fibrosis was stage F0 in 12 patients, F1 in 13 patients, F2 in 10 patients, F3 in 7 patients, and F4 in 4 patients. W-Ac increased with the progression of liver fibrosis up to stage F3. There were differences between F0 and F4 stages (p<0.001) and between any 2 stages of fibrosis (p<0.05), except for stages F3 and F4. There was a significant correlation between W-Ac and METAVIR score (r=0.795, p<0.001). W-Ac differed between non-fibrosis (F0) and fibrosis (F1-F4) groups (p<0.001) and in the normal (F0), early fibrosis (F1-2), and late fibrosis groups (F3-4) (p<0.001). ROC area under the curve was 0.890, and at a cut-off of 0.12153, sensitivity was 0.706 and specificity was 0.830.

CONCLUSIONS

W-Ac allowed assessment of liver fibrosis in clinical practice.

Prevalence, clinical characteristics, risk factors, and indicators for lean Chinese adults with nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic diseases in the world. Nowadays, the percentage of non-obese or lean patients with NAFLD is increasing. NAFLD in non-obese populations, especially the lean subgroup with a normal waist circumference (WC), might lead to more problems than obese individuals, as these individuals may not visit clinics for NAFLD diagnosis or ignore the diagnosis of NAFLD. If the precise characteristics of these populations, especially the lean subgroup, are identified, the clinicians would be able to provide more appropriate advice and treatment to these populations.

AIM

To investigate the prevalence, clinical characteristics, risk factors, and possible indicators for NAFLD in lean Chinese adults with a normal WC.

METHODS

People without diabetes mellitus or significant alcohol consumption who underwent routine health examinations were included. Their fatty liver index (FLI), abdominal ultrasonography results, and controlled attenuation parameter were all assessed. Genotyping for single-nucleotide polymorphisms associated with NAFLD was performed in another small group consisting of biopsy-proven NAFLD subjects and healthy controls.

RESULTS

A total of 2715 subjects who underwent routine health examinations were included in the study. Among 810 lean participants with a normal WC, 142 (17.5%) fulfilled the diagnostic criteria for NAFLD. Waist-height ratio, hemoglobin, platelets, and triglycerides were significant factors associated with the presence of NAFLD in these participants. The appropriate cut-off value of the FLI score in screening for NAFLD in the lean subjects with a normal WC was 25.15, which had a 77.8% sensitivity and 75.9% specificity. There was no significant difference in the single-nucleotide polymorphisms in the SIRT1, APOC3, PNPLA3, AGTR1, and PPARGC1A genes between lean subjects with and without NAFLD (P < 0.05).

CONCLUSION

NAFLD is not uncommon in lean Chinese adults even with a normal WC. Metabolic factors, rather than genetic factors, may play important roles in the development of NAFLD in this population. A lower cut-off value of the FLI score in screening for NAFLD should be used for lean Chinese adults with a normal WC.

Ultrasound Backscatter Envelope Statistics Parametric Imaging for Liver Fibrosis Characterization: A Review

Early detection and diagnosis of liver fibrosis is of critical importance. Currently the gold standard for diagnosing liver fibrosis is biopsy. However, liver biopsy is invasive and associated with sampling errors and can lead to complications such as bleeding. Therefore, developing noninvasive imaging techniques for assessing liver fibrosis is of clinical value. Ultrasound has become the first-line tool for the management of chronic liver diseases. However, the commonly used B-mode ultrasound is qualitative and can cause interobserver or intraobserver difference. Ultrasound backscatter envelope statistics parametric imaging is an important group of quantitative ultrasound techniques that have been applied to characterizing different kinds of tissue. However, a state-of-the-art review of ultrasound backscatter envelope statistics parametric imaging for liver fibrosis characterization has not been conducted. In this paper, we focused on the development of ultrasound backscatter envelope statistics parametric imaging techniques for assessing liver fibrosis from 1998 to September 2019. We classified these techniques into six categories: constant false alarm rate, fiber structure extraction technique, acoustic structure quantification, quantile-quantile probability plot, the multi-Rayleigh model, and the Nakagami model. We presented the theoretical background and algorithms for liver fibrosis assessment by ultrasound backscatter envelope statistics parametric imaging. Then, the specific applications of ultrasound backscatter envelope statistics parametric imaging techniques to liver fibrosis evaluation were reviewed and analyzed. Finally, the pros and cons of each technique were discussed, and the future development was suggested.

Quantitative assessment of media concentration using the Homodyned K distribution

The Homodyned K distribution has been used successfully as a tool in the ultrasound characterization of sparse media, where the scatterer clustering parameter α accurately discriminates between media with different numbers of scatterers per resolution cell. However, as the number of scatterers increases and the corresponding amplitude statistics become Rician, the reliability of the α estimates decreases rapidly. In the present study, we assess the usefulness of α for the characterization of both sparse and concentrated media, using simulated independent and identically distributed (i.i.d.) samples from Homodyned K distributions, ultrasound images of media with up to 68 scatterers per resolution cell and ultrasound signals acquired from particle phantoms with up to 101 scatterers per resolution cell. All parameter estimates are obtained using the XU estimator (Destrempes et al., 2013). Results suggest that the parameter α can be used to distinguish between media with up to 40 scatterers per resolution cell at 22 MHz, provided that parameter estimation can be performed on very large sample sizes (i.e., >10,000 i.i.d. samples).

Quantitative Ultrasound in Ex Vivo Fibrotic Rabbit Livers

Liver fibrosis is the common result of chronic liver disease. Diagnosis and grading liver fibrosis for patient management is mainly based on blood tests and hepatic puncture-biopsy, which is particularly invasive. Quantitative ultrasound (QUS) techniques provide insight into tissue microstructure and are based on the frequency-based analysis of the signals from biologic tissues. This study aims to quantify how spectral-based QUS parameters change with fibrosis grade. The changes in QUS parameters of healthy and fibrotic rabbit liver samples were investigated and were compared with the changes in liver stiffness, using shear wave elastography. Overall, the acoustic concentration was found to decrease with increasing fibrosis grade, and the effective scatterer size was found to be higher in fibrotic livers when compared with normal liver. The result of this study indicates that the combination of three QUS parameters (stiffness, effective scatterer size and acoustic concentration) provides the best classification performance, especially for classifying healthy and fibrotic livers.

Association between non-invasively diagnosed hepatic steatosis and chronic kidney disease in Chinese adults on their health check-up

OBJECTIVE

To explore the association between chronic kidney disease (CKD), graded by the estimated glomerular filtration rate (eGFR), and non-alcoholic fatty liver disease (NAFLD) using controlled attenuation parameter (CAP) and fatty liver index (FLI) values in Chinese adults undergoing routine health examinations.

METHODS

A total of 731 adult participants without diabetes mellitus or significant alcohol consumption who underwent routine health examinations were included. Their eGFR, CAP, FLI and abdominal ultrasonography results were assessed.

RESULTS

The prevalence of ultrasound-diagnosed NAFLD and CKD (eGFR <60 mL/min per 1.73 m² ) was 36.1% and 6.6%, respectively. CKD was more common in NAFLD patients than in those without (10.6% vs 4.3%, P < 0.001). The CAP and FLI values were significantly higher in the NAFLD group than in those without, but the change in the eGFR was negligible between the two groups. eGFR was negatively correlated with CAP (r = -0.189, P = 0.003) and FLI values (r = -0.130, P = 0.045). Moreover, eGFR was significantly lower in participants with CAP >292 dBm or FLI ≥60 than in those with CAP <238 dBm or FLI <30, respectively (both P < 0.05). The CAP value (odds ratio [OR] 1.099, 95% confidence interval [CI] 1.091-1.108, P = 0.021) was an independent risk factor for CKD.

CONCLUSIONS

A diagnosis of hepatic steatosis is related to an increased risk of CKD among non-alcoholic and non-diabetic Chinese adults regardless of whether the diagnosis was acquired via ultrasound, CAP or FLI. Increased hepatic lipid content may contribute to CKD development.

Can early hepatic fibrosis stages be discriminated by combining ultrasonic parameters?

In this study, we put forward a new approach to classify early stages of fibrosis based on a multiparametric characterization using backscatter ultrasonic signals. Ultrasonic parameters, such as backscatter coefficient (Bc), speed of sound (SoS), attenuation coefficient (Ac), mean scatterer spacing (MSS), and spectral slope (SS), have shown their potential to differentiate between healthy and pathologic samples in different organs (eye, breast, prostate, liver). Recently, our group looked into the characterization of stages of hepatic fibrosis using the parameters cited above. The results showed that none of them could individually distinguish between the different stages. Therefore, we explored a multiparametric approach by combining these parameters in two and three, to test their potential to discriminate between the stages of liver fibrosis: F0 (normal), F1, F3, and/without F4 (cirrhosis), according to METAVIR Score. Discriminant analysis showed that the most relevant individual parameter was Bc, followed by SoS, SS, MSS, and Ac. The combination of (Bc, SoS) along with the four stages was the best in differentiating between the stages of fibrosis and correctly classified 85% of the liver samples with a high level of significance (p<0.0001). Nevertheless, when taking into account only stages F0, F1, and F3, the discriminant analysis showed that the parameters (Bc, SoS) and (Bc, Ac) had a better classification (93%) with a high level of significance (p<0.0001). The combination of the three parameters (Bc, SoS, and Ac) led to a 100% correct classification. In conclusion, the current findings show that the multiparametric approach has great potential in differentiating between the stages of fibrosis, and thus could play an important role in the diagnosis and follow-up of hepatic fibrosis.

Speed of sound in diseased liver observed by scanning acoustic microscopy with 80 MHz and 250 MHz

In this study, the speed of sound (SOS) of two types of rat livers (eight normal livers, four cirrhotic livers) was measured with a scanning acoustic microscope using two transducers, one of which had an 80-MHz and the other a 250-MHz center frequency. The 250-MHz transducer had a better spatial resolution adapted to studying fiber or hepatic parenchymal cells. In normal livers, averages of the SOS values were from 1598 to 1677 m/s at 80-MHz and from 1568 to 1668 m/s at 250-MHz. In the fiber tissue of cirrhotic livers, averages of the SOS values were from 1645 to 1658 m/s at 80-MHz and from 1610 to 1695 m/s at 250-MHz, while the SOS values in the other tissue of cirrhotic livers ranged from 1644 to 1709 m/s at 80-MHz and from 1641 to 1715 m/s at 250-MHz. In one liver, SOS in fiber tissue was larger than that of tissues without fiber while in others it was lower. The resulting two-dimensional SOS maps provide a unique quantitative insight of liver acoustic microstructures in a healthy liver and in a cirrhotic ones. This study would be helpful to understand the complex relationship between acoustic properties and liver disease including fiber tissue.

Effect of Non-Alcoholic Fatty Liver Disease on Estimated Glomerular Filtration Rate Could Be Dependent on Age

There is a gap between the association of non-alcoholic fatty liver disease (NAFLD) and renal function in an apparently healthy population. This study aims to assess whether NAFLD is associated with estimated glomerular filtration rate (eGFR) levels and to understand early changes of eGFR in NAFLD. A cross-sectional study was performed among apparently healthy persons who underwent general health screening including laboratory assessments and hepatic ultrasonography from January 2013 to December 2013 at the First Affiliated Hospital of Zhejiang University, College of Medicine, China. This study included 1,193 subjects with a mean age of 48 years. Prevalence of NAFLD was 31.3%. Mean eGFR was significantly lower in NAFLD than in controls (107 ± 19 mL/min/1.73 m(2) vs. 113 ± 23 mL/min/1.73 m(2), P<0.001). Correlation analysis between eGFR and NAFLD related risk factors revealed an inverse correlation between eGFR levels and some NAFLD risk factors (all P<0.01). All subjects were classified into five phases according to age. Average eGFR levels of NAFLD were lower than controls in three phases for subjects with ≤ 50 years of age (all P<0.05), while there were no significant differences on average eGFR levels between NAFLD and controls in two phases for subjects with >50 years of age (Both P>0.05). The eGFR level is significantly associated with NAFLD and its risk factors in an apparently healthy population. Effects of NAFLD on eGFR could be dependent on age.

Ultrasound method applied to characterize healthy femoral diaphysis of Wistar rats in vivo

A simple experimental protocol applying a quantitative ultrasound (QUS) pulse-echo technique was used to measure the acoustic parameters of healthy femoral diaphyses of Wistar rats in vivo. Five quantitative parameters [apparent integrated backscatter (AIB), frequency slope of apparent backscatter (FSAB), time slope of apparent backscatter (TSAB), integrated reflection coefficient (IRC), and frequency slope of integrated reflection (FSIR)] were calculated using the echoes from cortical and trabecular bone in the femurs of 14 Wistar rats. Signal acquisition was performed three times in each rat, with the ultrasound signal acquired along the femur's central region from three positions 1 mm apart from each other. The parameters estimated for the three positions were averaged to represent the femur diaphysis. The results showed that AIB, FSAB, TSAB, and IRC values were statistically similar, but the FSIR values from Experiments 1 and 3 were different. Furthermore, Pearson's correlation coefficient showed, in general, strong correlations among the parameters. The proposed protocol and calculated parameters demonstrated the potential to characterize the femur diaphysis of rats in vivo. The results are relevant because rats have a bone structure very similar to humans, and thus are an important step toward preclinical trials and subsequent application of QUS in humans.

Ultrasonic integrated backscatter in assessing liver steatosis before and after liver transplantation

BACKGROUND

Liver steatosis affects 20%-30% of adults. Because of the increasing gap between graft supplies and demands, livers with steatosis are frequently used in liver transplantation. But severely steatotic liver grafts are associated with a high risk of intraoperative and postoperative complications. Accurate assessment of fat content of donor livers and monitoring of the extent of steatosis in recipients are required for liver transplantation. The present study aimed to determine the correlation between liver echogenicity and fat content, and to evaluate the use of an ultrasonic integrated backscatter system (IBS) in the assessment of changes in fat content after liver transplantation.

METHODS

Seventy-nine consecutive patients receiving liver grafts from living donors were evaluated in our center. Of these recipients, 67 survived for more than two years and were included in this study. Each liver graft was evaluated with IBS and ultrasound before operation and the fat content was estimated. The fat content of the grafts in the recipients was again assessed with ultrasound at 18 months after surgery.

RESULTS

A correlation was detected between each graft's IBS value and its fat content (P=0.001). The IBS value in fatty grafts with various degrees of steatosis was significantly decreased in 3 (P=0.02), 12, 15 and 18 (P=0.001) months after orthotopic liver transplantation. The IBS value returned to normal in all patients in 18 months after liver transplantation.

CONCLUSIONS

Decreased fat content in steatotic grafts can be observed in all recipients. Ultrasonic IBS is useful in determining the steatotic degree of grafts in donors as well as in monitoring the grafts after liver transplantation.

Relationship between serum osteocalcin levels and non-alcoholic fatty liver disease in adult males, South China

AIM

To determine serum osteocalcin levels in South Chinese males with non-alcoholic fatty liver disease (NAFLD) and to examine the relation between serum osteocalcin and NAFLD.

METHODS

Data were collected from 1683 men attending the Fangchenggang Area Male Healthy and Examination Survey (FAMHES) from September 2009 to December 2009. Serum osteocalcin was measured with electrochemiluminescence immunoassay. An abdominal ultrasonographic examination for all individuals was performed by two experienced ultrasonographers. The associations of serum osteocalcin with NAFLD were evaluated.

RESULTS

The levels of serum osteocalcin were lower in 364 NAFLD participants than in 1319 non-NAFLD participants (24.51 ± 1.38 ng/mL vs. 20.81 ± 1.33 ng/mL, p < 0.001). Serum osteocalin level was associated with the scale of NAFLD (r = -0.150, p < 0.01). Serum osteocalin level tended to decrease with the scale of NAFLD. Binary logistic regression analysis showed that decreased ORs for NAFLD were observed from the first to the fourth osteocalcin quartiles.

CONCLUSIONS

Our findings suggest that a lower serum osteocalcin level is associated with the presence of NAFLD.

Serum uric acid and non-alcoholic fatty liver disease in non-diabetic Chinese men

Increased serum uric acid (SUA) levels may be involved in the development of non-alcoholic fatty liver disease (NAFLD) in men presenting with metabolic syndrome (MetS) and/or insulin resistance. We aimed to determine the independent relationship between SUA and NAFLD in non-diabetic Chinese male population, and to explore the determinants of SUA levels among indexes of adiposity, lipid, and genotypes pertaining to triglycerides metabolism, inflammation, oxidative stress, and SUA concentrations. A total of 1440 men, classified depending on the presence of ultrasonographically detected NAFLD, underwent a complete healthy checkup program. Genotypes were extracted from our previously established genome-wide association study database. After adjusting for age, smoking, drinking, body mass index, homeostasis model assessment of insulin resistance, C-reactive protein, creatinine, alanine aminotransferase (ALT) and components of metabolic syndrome, the odds ratio for NAFLD, comparing the highest with the lowest SUA quartile, was 2.81 (95% confidence interval 1.66–4.76). A stepwise multivariate linear regression analysis (R² = 0.238, P<0.001) retained age, waist circumference, serum creatinine, triglycerides, the Q141K variant in ABCG2 (rs2231142) and NAFLD as significant predictors of SUA levels (all P<0.001). Besides, ALT and Met196Arg variant in TNFRSF1B (rs1061622) additionally associated with SUA among individuls with NAFLD. Our data suggest that in Chinese men, elevated SUA is significantly associated with NAFLD, independent of insulin resistance and other metabolic disorders, such as central obesity or hypertriglyceridemia. Meanwhile, among subjects with NAFLD, index of liver damage, such as elevated ALT combined with genetic susceptibility to inflammation associated with increased SUA levels.

Classification and staging of chronic liver disease from multimodal data

Chronic liver disease (CLD) is most of the time an asymptomatic, progressive, and ultimately potentially fatal disease. In this study, an automatic hierarchical procedure to stage CLD using ultrasound images, laboratory tests, and clinical records are described. The first stage of the proposed method, called clinical based classifier (CBC), discriminates healthy from pathologic conditions. When nonhealthy conditions are detected, the method refines the results in three exclusive pathologies in a hierarchical basis: 1) chronic hepatitis; 2) compensated cirrhosis; and 3) decompensated cirrhosis. The features used as well as the classifiers (Bayes, Parzen, support vector machine, and k -nearest neighbor) are optimally selected for each stage. A large multimodal feature database was specifically built for this study containing 30 chronic hepatitis cases, 34 compensated cirrhosis cases, and 36 decompensated cirrhosis cases, all validated after histopathologic analysis by liver biopsy. The CBC classification scheme outperformed the nonhierachical one against all scheme, achieving an overall accuracy of 98.67% for the normal detector, 87.45% for the chronic hepatitis detector, and 95.71% for the cirrhosis detector.

Oestradiol is a protective factor for non-alcoholic fatty liver disease in healthy men

Visceral fat is a risk factor for non-alcoholic fatty liver disease (NAFLD). A reduction in sex hormones is associated with increased abdominal fat. Thus, we investigated whether reduced testosterone (T) or oestradiol (E2) levels in men are associated with NAFLD and central obesity. The study involved a survey of 1,882 men between 20 and 60 years of age. We detected hepatic fat infiltration by ultrasound. Early morning serum was analyzed for total testosterone (TT), E2, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Free testosterone (FT) was calculated using the Vermeulen method. In the studied population, the prevalence of NAFLD, FSH, LH and SHBG increased with age, TT and FT declined with age, and E2 remained stable. However, in the NAFLD group, TT remained stable, FT and E2 declined, and hepatic fat infiltration increased (P < 0.001 for both). Using multivariate analysis, a correlation was found between E2 and NAFLD, with an odds ratio of 0.954 (95% confidence interval: 0.946-0.967). E2 is one of the protective factors against NAFLD in healthy men. T has no significant correlation with NAFLD. Further investigation would be required to assess the clinical consequences of reduced E2 in men with NAFLD, particularly for men whose TT remained stable.

Using ultrasound Nakagami imaging to assess liver fibrosis in rats

This study explored the feasibility of using the ultrasound Nakagami image to assess the degree of liver fibrosis in rats. The rat has been widely used as a model in investigations of liver fibrosis. Ultrasound grayscale imaging makes it possible to observe fibrotic rat livers in real time. Statistical analysis of the envelopes of signals backscattered from rat livers may provide useful clues about the degree of liver fibrosis. The Nakagami-model-based image has been shown to be useful for characterizing scatterers in tissues by reflecting the echo statistics, and hence the Nakagami image may serve as a functional imaging tool for quantifying rat liver fibrosis. To validate this idea, fibrosis was induced in each rat liver (n=21) by an intraperitoneal injection of 0.5% dimethylnitrosamine. Livers were excised from rats for in vitro ultrasound scanning using a single-element transducer. The backscattered-signal envelopes of the acquired raw ultrasound signals were used for Nakagami imaging. The Metavir score determined by a pathologist was used to histologically quantify the degree of liver fibrosis. It was found that the Nakagami image could be used to distinguish different degrees of liver fibrosis in rats, since the average Nakagami parameter increased from 0.55 to 0.83 as the fibrosis score increased from 0 (i.e., normal) to 4. This correlation may be due to liver fibrosis in rats involving an increase in the concentration of local scatterers and the appearance of the periodic structures or clustering of scatterers that would change the backscattering statistics. The current findings indicate that the ultrasound Nakagami image has great potential as a functional imaging tool to complement the use of the conventional B-scan in animal studies of liver fibrosis.

Characterization of pseudarthrosis with ultrasound backscattered signals in rats

PURPOSE

To propose a novel model of pseudarthrosis in a small animal and to investigate the ability of backscatter parameters from ultrasound signals in differentiating normal bone from those ones with pseudarthrosis.

METHODS

Twelve Rattus norvegicus albinus free from pathogenic species (SPF) were randomly divided in two groups, with six animals each. In the Control group a surgical approach to the femur was made, followed by the synthesis of the muscle and skin layers. The Experimental group was submitted to an osteotomy of the femur and a vascularized flap of the fascia lata was interposed in the line of the fractured bone. Then the alignment and bone stabilization were accomplished, by using nylon stitch in U shape introduced in holes made in the proximal and distal fractured bone. Bone samples were scanned with ultrasound and signals were collected for each one to analyze the parameter Apparent Integrated Backscatter - AIB.

RESULTS

Radiological and anatomopathologic studies revealed the absence of bone consolidation with persistence of fiber-osteoid tissue. Values of the ultrasound parameter AIB from normal bones were statistically different from those with pseudarthrosis.

CONCLUSION

The experimental model was suitable for pseudarthrosis development in rats and the ultrasound backscatter parameters were able to identify such a bone disease in vitro.

Three-dimensional ultrasonic Nakagami imaging for tissue characterization

The two-dimensional (2D) Nakagami image complements the ultrasound B-scan image when attempting to visualize the scatterer properties of tissues. The resolution of the Nakagami image is lower than that of the B-scan image, since the former is produced by processing the raw envelope data using a 2D sliding window with side lengths typically corresponding to three times the pulse length of the incident ultrasound. This paper proposes using three-dimensional (3D) Nakagami imaging for improving the resolution of the obtained Nakagami image and providing more complete information of scatterers for a better tissue characterization. The 3D Nakagami image is based on a voxel array composed of the Nakagami parameters constructed using a 3D sliding cube to process the 3D backscattered raw data. Experiments on phantoms with different scatterer concentrations were carried out to determine the optimal size of the sliding cube for a stable estimation of the Nakagami parameter. Tissue measurements on rat livers without and with fibrosis formation were further used to explore the practical feasibility of 3D Nakagami imaging. The results indicated that the side length of the cube used to construct the 3D Nakagami image must be at least two times the pulse length, which improved the resolution for each Nakagami image frame in the 3D Nakagami image. The results further demonstrated that the 3D Nakagami image is better than the conventional 2D Nakagami image for complementing the B-scan in detecting spatial variations in the scatterer concentration and classifying normal and fibrotic livers. This study suggests that 3D Nakagami imaging has the potential to become a new 3D quantitative imaging approach.

A novel power spectrum calculation method using phase-compensation and weighted averaging for the estimation of ultrasound attenuation

An estimation of ultrasound attenuation in soft tissues is critical in the quantitative ultrasound analysis since it is not only related to the estimations of other ultrasound parameters, such as speed of sound, integrated scatterers, or scatterer size, but also provides pathological information of the scanned tissue. However, estimation performances of ultrasound attenuation are intimately tied to the accurate extraction of spectral information from the backscattered radiofrequency (RF) signals. In this paper, we propose two novel techniques for calculating a block power spectrum from the backscattered ultrasound signals. These are based on the phase-compensation of each RF segment using the normalized cross-correlation to minimize estimation errors due to phase variations, and the weighted averaging technique to maximize the signal-to-noise ratio (SNR). The simulation results with uniform numerical phantoms demonstrate that the proposed method estimates local attenuation coefficients within 1.57% of the actual values while the conventional methods estimate those within 2.96%. The proposed method is especially effective when we deal with the signal reflected from the deeper depth where the SNR level is lower or when the gated window contains a small number of signal samples. Experimental results, performed at 5MHz, were obtained with a one-dimensional 128 elements array, using the tissue-mimicking phantoms also show that the proposed method provides better estimation results (within 3.04% of the actual value) with smaller estimation variances compared to the conventional methods (within 5.93%) for all cases considered.

Use of nakagami statistics and empirical mode decomposition for ultrasound tissue characterization by a nonfocused transducer

The Nakagami parameter associated with the Nakagami distribution estimated from ultrasonic backscattered signals reflects the scatterer concentration in a tissue. A nonfocused transducer does not allow tissue characterization based on the Nakagami parameter. This paper proposes a new method called the noise-assisted Nakagami parameter based on empirical mode decomposition of noisy backscattered echoes to allow quantification of the scatterer concentration based on data obtained using a nonfocused transducer. To explore the practical feasibility of the proposed method, the current study performed experiments on phantoms and measurements on rat livers in vitro with and without fibrosis induction. The results show that using a nonfocused transducer makes it possible to use the noise-assisted Nakagami parameter to classify phantoms with different scatterer concentrations and different stages of liver fibrosis in rats more accurately than when using techniques based on the echo intensity and the conventional Nakagami parameter. However, the conventional Nakagami parameter and the noise-assisted Nakagami parameter have different meanings: the former represents the statistics of signals backscattered from unresolvable scatterers, whereas the latter is associated with stronger resolvable scatterers or local inhomogeneity caused by scatterer aggregation.

Simulation of elastic wave scattering in cells and tissues at the microscopic level

The scattering of longitudinal and shear waves from spherical, nucleated cells and three-dimensional tissues with simple and hierarchical microstructures was numerically modeled at the microscopic level using an iterative multipole approach. The cells were modeled with a concentric core-shell (nucleus-cytoplasm) structure embedded in an extracellular matrix. Using vector multipole expansions and boundary conditions, scattering solutions were derived for single cells with either solid or fluid properties for each of the cell components. Tissues were modeled as structured packings of cells. Multiple scattering between cells was simulated using addition theorems to translate the multipole fields from cell to cell in an iterative process. Backscattering simulations of single cells indicated that changes in the shear properties and nuclear diameter had the greatest effect on the frequency spectra. Simulated wave field images and high-frequency spectra (15-75 MHz) from tissues containing 1211-2137 cells exhibited up to 20% enhancement of the field amplitudes at the plasma membrane, significant changes in spectral features due to neoplastic and other microstructural alterations, and a detection threshold of approximately 8.5% infiltration of tumor cells into normal tissue. These findings suggest that histology-based simulations may provide insight into fundamental ultrasound-tissue interactions and help in the development of new medical technologies.

Hybrid spectral domain method for attenuation slope estimation

Attenuation estimation methods for medical ultrasound are important because attenuation properties of soft tissue can be used to distinguish between benign and malignant tumors and to detect diffuse disease. The classical spectral shift method and the spectral difference method are the most commonly used methods for the estimation of the attenuation; however, they both have specific limitations. Classical spectral shift approaches for estimating ultrasonic attenuation are more sensitive to local spectral noise artifacts and have difficulty in compensating for diffraction effects because of beam focusing. Spectral difference approaches, on the other hand, fail to accurately estimate attenuation coefficient values at tissue boundaries that also possess variations in the backscatter. In this paper, we propose a hybrid attenuation estimation method that combines the advantages of the spectral difference and spectral shift methods to overcome their specific limitations. The proposed hybrid method initially uses the spectral difference approach to reduce the impact of system-dependent parameters including diffraction effects. The normalized power spectrum that includes variations because of backscatter changes is then filtered using a Gaussian filter centered at the transmit center frequency of the system. A spectral shift method, namely the spectral cross-correlation algorithm is then used to compute spectral shifts from these filtered power spectra to estimate the attenuation coefficient. Ultrasound simulation results demonstrate that the estimation accuracy of the hybrid method is better than the centroid downshift method (spectral shift method), in uniformly attenuating regions. In addition, this method is also stable at boundaries with variations in the backscatter when compared with the reference phantom method (spectral difference method). Experimental results using tissue-mimicking phantom also illustrate that the hybrid method is more robust and provides accurate attenuation estimates in both uniformly attenuating regions and across boundaries with backscatter variations. The proposed hybrid method preserves the advantages of both the spectral shift and spectral difference approaches while eliminating the disadvantages associated with each of these methods, thereby improving the accuracy and robustness of the attenuation estimation.

Statistical relevance of ultrasonographic criteria in the assessment of diffuse liver disease in dogs and cats

OBJECTIVE

To determine whether objectively applied ultrasonographic interpretive criteria are statistically useful in differentiating among 7 defined categories of diffuse liver disease in dogs and cats.

SAMPLE POPULATION

Ultrasonographic images of 229 dogs and 104 cats.

PROCEDURES

Liver parenchymal or related sonographic criteria established by the authors were retrospectively and independently applied by 3 radiologists who were not aware of patient status or patient laboratory data. Seven histologic or cytologic categories of diffuse (infiltrative but not nodular) liver diseases were jointly established by the authors and included normal liver; inflammation; round-cell neoplasia; non-round-cell infiltrative, prenodular (early) metastatic neoplasia; lipidosis; vacuolar hepatopathy; and other. Liver parenchymal sonographic criteria included parenchymal sound attenuation with increasing depth, comparative organ echogenicity (liver, spleen, and kidneys), diffuse or patchy hyperechoic or hypoechoic echotexture, uniform or coarse echotexture, portal venous clarity, and liver lobe geometry. Related extrahepatic criteria included gallbladder wall thickness, bile duct diameter, amount and character of gallbladder precipitate, nondependent shadowing in the gallbladder, hepatic vein diameter versus caudal vena cava diameter, peritoneal fluid, spleen echotexture (normal vs abnormal [characterized]), and kidney echotexture. Ultrasonographic criteria were statistically compared to the 7 categories of diffuse liver disease in search of clinically exploitable relationships.

RESULTS

Statistical evaluation of the applied ultrasonographic criteria did not yield clinically acceptable accuracy for discrimination among the 7 categories of diffuse liver diseases (including normal liver) in either species.

CONCLUSIONS AND CLINICAL RELEVANCE

Criterion-based ultrasonographic appearance was insufficient to discriminate among canine and feline diffuse infiltrative liver diseases.

Quantitative ultrasonic tissue characterization as a new tool for continuous monitoring of chronic liver remodelling in mice

BACKGROUND/AIM

Recognition of the limitations of liver biopsies has led to the need for non-invasive tests to assess liver fibrosis from intensity and kinetic point of views. The aim of the present study was to evaluate non-invasive ultrasonic tissue characterization for the continuous monitoring of this process in mice.

METHODS

Twelve-week-old male and female C57Bl6/J mice were submitted to repetitive carbon-tetrachloride (CCl4) intraperitoneal injections during 8 weeks or analysed 28 days after common bile duct ligation (BDL). The extent and kinetic of the disease progression were followed by the measurement of ultrasound backscatter intensity. This was compared with histological and blood parameter analysis.

RESULTS

CCl4 induced a progressive increase in in vivo liver tissue backscatter intensity in both males and females. This increase was mainly correlated with interstitial fibrosis and, to a lower extent, with nuclear surface of the hepatocytes. A similar result was found after BDL.

CONCLUSIONS

These data demonstrate for the first time in a systematic study that ultrasound tissue characterization can be used as a reliable tool to follow liver remodelling in mice continuously.