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

Alignment analysis between teacher-made tests with the learning objectives in a selected school of central regional state of Ethiopia

Alignment studies can offer valuable insights to educators about the effectiveness of the course objectives, assessments, and teaching. In this particular study, the aim was to determine the extent to which teacher-made tests aligned with the learning objectives of natural science subjects. The study included a total of 180 learning objectives (46 from Biology, 71 from Chemistry, and 63 from Physics) and 88 test items (30 from Biology, 30 from Chemistry, and 28 from Physics). Bloom's revised taxonomy was used to identify, organize, and code the objectives and test items. Porter's alignment index was used to analyze the data, allowing for determining the degree of alignment between tests and learning objectives. The results showed that the overall alignment between teacher-made tests with course objectives was 45 % for Biology, 46 % for Chemistry, and 62 % for Physics. The study also found that a dependable degree of alignment was not yet established between learning objectives and tests. Therefore, it was suggested that teachers should use assessment procedures and blueprints that consider higher-order cognitive levels and expected learning objectives. Further investigations are also required to determine whether students are meeting the expected learning objectives and moving to the next grade level.

Comparison of Ultrasound Attenuation Imaging Using a Linear versus a Conventional Convex Probe: A Volunteer Study

The study aimed to investigate the feasibility of attenuation imaging (ATI) measurements using a linear probe on healthy volunteers and compare measurements with the conventional convex probe. Attenuation imaging measurements of the liver tissue were taken using ultrasound with a convex and a linear probe in 33 volunteers by two examining doctors, and the measurements were repeated 4-5 weeks later by one of them. The ATI values for the linear probe were in the range of the values for the convex probe for both examiners. Measurements did not change significantly for 32 out of 33 volunteers after 4-5 weeks when using the linear probe. The size of the region of interest (ROI) only impacted the ATI values for the convex probe; it did not affect the values taken with the linear probe. Healthy volunteers were measured, and their attenuation values were compared to those from a convex probe, commonly used in steatosis evaluation. When both probes were positioned in the same liver area, they showed good agreement in attenuation values, though depth significantly affected the measurements, with both probes providing different values at different depths. The study's results aligned with previous research using the same system. Operator A and B's results were compared, demonstrating similar ranges of values for both probes. The linear probe has been demonstrated to allow for superficial measurements and attain ATI values in line with that of the convex probe in the liver.

WFUMB Guidelines/Guidance on Liver Multiparametric Ultrasound. Part 2: Guidance on Liver Fat Quantification

The World Federation for Ultrasound in Medicine and Biology (WFUMB) has promoted the development of this document on multiparametric ultrasound. Part 2 is a guidance on the use of the available tools for the quantification of liver fat content with ultrasound. These are attenuation coefficient, backscatter coefficient, and speed of sound. All of them use the raw data of the ultrasound beam to estimate liver fat content. This guidance has the aim of helping the reader in understanding how they work and interpret the results. Confounding factors are discussed and a standardized protocol for measurement acquisition is suggested to mitigate them. The recommendations were based on published studies and experts' opinion but were not formally graded because the body of evidence remained low at the time of drafting this document.

Ultrasound-based steatosis grading system using 2D-attenuation imaging: An individual patient data meta-analysis with external validation

BACKGROUND AND AIMS

Noninvasive tools assessing steatosis, such as ultrasonography-based 2D-attenuation imaging (ATI), are needed to tackle the worldwide burden of steatotic liver disease. This one-stage individual patient data (IPD) meta-analysis aimed to create an ATI-based steatosis grading system.

APPROACH AND RESULTS

A systematic review (EMBASE + MEDLINE, 2018-2022) identified studies, including patients with histologically or magnetic resonance imaging proton-density fat fraction (MRI-PDFF)-verified ATI for grading steatosis (S0 to S3). One-stage IPD meta-analyses were conducted using generalized mixed models with a random study-specific intercept. Created ATI-based steatosis grading system (aS0 to aS3) was externally validated on a prospective cohort of patients with type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (n=174, histologically and MRI-PDFF-verified steatosis). Eleven enrolled studies included 1374 patients, classified into S0, S1, S2, and S3 in 45.4%, 35.0%, 9.3%, and 10.3% of the cases. ATI was correlated with histological steatosis ( r = 0.60; 95% CI: 0.52, 0.67; p < 0.001) and MRI-PDFF ( r = 0.70; 95% CI: 0.66, 0.73; p < 0.001) but not with liver stiffness ( r = 0.03; 95% CI: -0.04, 0.11, p = 0.343). Steatosis grade was an independent factor associated with ATI (coefficient: 0.24; 95% CI: [0.22, 0.26]; p < 0.001). ATI marginal means within S0, S1, S2, and S3 subpopulations were 0.59 (95% CI: [0.58, 0.61]), 0.69 (95% CI [0.67, 0.71]), 0.78 (95% CI: [0.76, 0.81]), and 0.85 (95% CI: [0.83, 0.88]) dB/cm/MHz; all contrasts between grades were significant ( p < 0.0001). Three ATI thresholds were calibrated to create a new ATI-based steatosis grading system (aS0 to aS3, cutoffs: 0.66, 0.73, and 0.81 dB/cm/MHz). Its external validation showed Obuchowski measures of 0.84 ± 0.02 and 0.82 ± 0.02 with histologically based and MRI-PDFF-based references.

CONCLUSIONS

ATI is a reliable, noninvasive marker of steatosis. This validated ATI-based steatosis grading system could be valuable in assessing patients with metabolic dysfunction-associated steatotic liver disease.

Quantitative ultrasound (QUS) in the evaluation of liver steatosis: data reliability in different respiratory phases and body positions

Liver steatosis is the most common chronic liver disease and affects 10-24% of the general population. As the grade of disease can range from fat infiltration to steatohepatitis and cirrhosis, an early diagnosis is needed to set the most appropriate therapy. Innovative noninvasive radiological techniques have been developed through MRI and US. MRI-PDFF is the reference standard, but it is not so widely diffused due to its cost. For this reason, ultrasound tools have been validated to study liver parenchyma. The qualitative assessment of the brightness of liver parenchyma has now been supported by quantitative values of attenuation and scattering to make the analysis objective and reproducible. We aim to demonstrate the reliability of quantitative ultrasound in assessing liver fat and to confirm the inter-operator reliability in different respiratory phases. We enrolled 45 patients examined during normal breathing at rest, peak inspiration, peak expiration, and semi-sitting position. The highest inter-operator agreement in both attenuation and scattering parameters was achieved at peak inspiration and peak expiration, followed by semi-sitting position. In conclusion, this technology also allows to monitor uncompliant patients, as it grants high reliability and reproducibility in different body position and respiratory phases.

Correlation between magnetic resonance imaging proton density fat fraction (MRI-PDFF) and liver biopsy to assess hepatic steatosis in obesity

Obesity is highly associated with Non-alcoholic fatty liver disease (NAFLD) and increased risk of liver cirrhosis and liver cancer-related death. We determined the diagnostic performance of the complex-based chemical shift technique MRI-PDFF for quantifying liver fat and its correlation with histopathologic findings in an obese population within 24 h before bariatric surgery. This was a prospective, cross-sectional, Institutional Review Board-approved study of PDFF-MRI of the liver and MRI-DIXON image volume before bariatric surgery. Liver tissues were obtained during bariatric surgery. The prevalence of NAFLD in the investigated cohort was as high as 94%. Histologic hepatic steatosis grades 0, 1, 2, and 3 were observed in 3 (6%), 25 (50%), 14 (28%), and 8 (16%) of 50 obese patients, respectively. The mean percentages of MRI-PDFF from the anterior and posterior right hepatic lobe and left lobe vs. isolate left hepatic lobe were 15.6% (standard deviation [SD], 9.28%) vs. 16.29% (SD, 9.25%). There was a strong correlation between the percentage of steatotic hepatocytes and MRI-PDFF in the left hepatic lobe (r = 0.82, p < 0.001) and the mean value (r = 0.78, p < 0.001). There was a strong correlation between MRI-derived subcutaneous adipose tissue volume and total body fat mass by dual-energy X-ray absorptiometry, especially at the L2-3 and L4 level (r = 0.85, p < 0.001). MRI-PDFF showed good performance in assessing hepatic steatosis and was an excellent noninvasive technique for monitoring hepatic steatosis in an obese population.

Interoperator reproducibility of quantitative ultrasound analysis of hepatic steatosis in participants with suspected MASLD: A prospective study

OBJECTIVES

To evaluate the reproducibility of tissue attenuation imaging (TAI) and tissue scatter distribution imaging (TSI) measurements in adults with suspected metabolic dysfunction-associated steatotic liver disease (MASLD) between radiologists with varying experience.

MATERIALS AND METHODS

Participants with suspected MASLD were prospectively recruited. TAI and TSI were performed for each participant by two radiologists with different levels of experience. Interoperability reliability was assessed on the basis of Bland-Altman analysis and intraclass correlation coefficients (ICCs). The study determined and compared the diagnostic performance of TAI and TSI with clinical prediction models using proton magnetic resonance spectroscopy (1H-MRS) as a reference.

RESULTS

A total of 180 participants (women, n = 56; men, n = 124, mean age, 46.98 ± 14.92 years; mean BMI, 25.81 ± 4.47) were enrolled from August 2022 to September 2022. Bland-Altman plots showed only slight deviation in the TAI and TSI results of the two radiologists; there was good interoperator reproducibility for TAI (ICC = 0.92) and TSI (ICC = 0.86). Senior and junior radiologists performed examinations labeled as TAI-1 and TSI-1, and TAI-2 and TSI-2, respectively. The areas under the curves (AUCs) of TAI-1, TAI-2, TSI-1, and TAI-2 for the detection of ≥5 % hepatic steatosis were 0.90, 0.96, 0.91 and 0.96, respectively. According to ROC analysis, the diagnostic performance of both radiologists for TAI and TSI was statistically similar and superior to that of the clinical prediction model.

CONCLUSIONS

TAI and TSI have good reproducibility between radiologists with different levels of experience. Meanwhile, both TAI and TSI demonstrated good diagnostic performance for hepatic steatosis (≥5%), surpassing that of clinical prediction models.

Altered probe pressure and body position increase diagnostic accuracy for men and women in detecting hepatic steatosis using quantitative ultrasound

OBJECTIVES

To evaluate the diagnostic performance of ultrasound guided attenuation parameter (UGAP) for evaluating liver fat content with different probe forces and body positions, in relation to sex, and compared with proton density fat fraction (PDFF).

METHODS

We prospectively enrolled a metabolic dysfunction-associated steatotic liver disease (MASLD) cohort that underwent UGAP and PDFF in the autumn of 2022. Mean UGAP values were obtained in supine and 30° left decubitus body position with normal 4 N and increased 30 N probe force. The diagnostic performance was evaluated by the area under the receiver operating characteristic curve (AUC).

RESULTS

Among 60 individuals (mean age 52.9 years, SD 12.9; 30 men), we found the best diagnostic performance with increased probe force in 30° left decubitus position (AUC 0.90; 95% CI 0.82-0.98) with a cut-off of 0.58 dB/cm/MHz. For men, the best performance was in supine (AUC 0.91; 95% CI 0.81-1.00) with a cut-off of 0.60 dB/cm/MHz, and for women, 30° left decubitus position (AUC 0.93; 95% CI 0.83-1.00), with a cut-off 0.56 dB/cm/MHz, and increased 30 N probe force for both genders. No difference was in the mean UGAP value when altering body position. UGAP showed good to excellent intra-reproducibility (Intra-class correlation 0.872; 95% CI 0.794-0.921).

CONCLUSION

UGAP provides excellent diagnostic performance to detect liver fat content in metabolic dysfunction-associated steatotic liver diseases, with good to excellent intra-reproducibility. Regardless of sex, the highest diagnostic accuracy is achieved with increased probe force with men in supine and women in 30° left decubitus position, yielding different cut-offs.

CLINICAL RELEVANCE STATEMENT

The ultrasound method ultrasound-guided attenuation parameter shows excellent diagnostic accuracy and performs with good to excellent reproducibility. There is a possibility to alter body position and increase probe pressure, and different performances for men and women should be considered for the highest accuracy.

KEY POINTS

• There is a possibility to alter body position when performing the ultrasound method ultrasound-guided attenuation parameter. • Increase probe pressure for the highest accuracy. • Different performances for men and women should be considered.

Multiparametric US for Identifying Metabolic Dysfunction-associated Steatohepatitis: A Prospective Multicenter Study

Background Noninvasive evaluation of metabolic dysfunction-associated fatty liver disease (MAFLD) with multiparametric US is essential, but multicenter studies are lacking. Purpose To evaluate the ability of multiparametric US with attenuation imaging (ATI) and two-dimensional (2D) shear-wave elastography (SWE) for predicting metabolic dysfunction-associated steatohepatitis (MASH) in participants with MAFLD, regardless of hepatitis B virus infection status. Materials and Methods This prospective cross-sectional multicenter study of consecutive adults with MAFLD who underwent multiparametric US with ATI and 2D SWE, as well as liver biopsy, from September 2020 to June 2022 was conducted in 12 tertiary hospitals in China. Multivariable logistic regression was performed to assess risk factors associated with MASH. Area under the receiver operating characteristic curve (AUC) analysis was used to evaluate diagnostic performance in predicting MASH in training and validation groups (6:4 ratio of participants), and for a post hoc subgroup analysis of hepatitis B virus infection and diabetes. Results A total of 424 participants (median age, 47 years; IQR, 34-59 years; 244 male) were evaluated, including 332 participants (78%) with MASH and 92 (22%) without. Attenuation coefficient (AC) (odds ratio [OR], 3.32 [95% CI: 1.94, 5.71]; P < .001), alanine aminotransferase (ALT) level (OR, 4.42 [95% CI: 1.78, 10.94]; P = .001), and international normalized ratio (INR) (OR, 0.59 [95% CI: 0.37, 0.95]; P = .03) were independently associated with MASH. A combined model (AC, ALT, and INR) had AUCs of 0.85 (95% CI: 0.79, 0.91) and 0.77 (95% CI: 0.69, 0.85) for predicting MASH in the training and validation groups, respectively. AUC values for the subgroups with and without diabetes were 0.83 (95% CI: 0.72, 0.94) and 0.81 (95% CI: 0.75, 0.87) and for the subgroups with and without hepatitis B were 0.82 (95% CI: 0.74, 0.90) and 0.79 (95% CI: 0.71, 0.87), respectively. Conclusion A model combining AC, ALT level, and INR showed good discrimination ability for predicting MASH in participants with MAFLD. Clinical trial registration no. NCT04551716 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Reuter in this issue.

Inter-platform reproducibility of ultrasound-based fat fraction for evaluating hepatic steatosis in nonalcoholic fatty liver disease

OBJECTIVES

To evaluate the inter-platform reproducibility of ultrasound-based fat fraction examination in nonalcoholic fatty liver disease (NAFLD).

METHODS

Patients suspected of having NAFLD were prospectively enrolled from January 2023. Ultrasound-based fat fraction examinations were performed using two different platforms (ultrasound-derived fat fraction [UDFF] and quantitative ultrasound-derived estimated fat fraction [USFF]) on the same day. The correlation between UDFF and USFF was assessed using Pearson correlation coefficient. Intraclass correlation coefficient (ICC), Bland-Altman analysis with 95% limits of agreement (LOAs), and the coefficient of variation (CV) were used to assess inter-platform reproducibility.

RESULTS

A total of 41 patients (21 men and 20 women; mean age, 53.9 ± 12.6 years) were analyzed. Moderate correlation was observed between UDFF and USFF (Pearson's r = 0.748; 95% confidence interval [CI]: 0.572-0.858). On Bland-Altman analysis, the mean difference between UDFF and USFF values was 1.3% with 95% LOAs ranging from -8.0 to 10.6%. The ICC between UDFF and USFF was 0.842 (95% CI: 0.703-0.916), with a CV of 29.9%.

CONCLUSION

Substantial inter-platform variability was observed among different ultrasound-based fat fraction examinations. Therefore, it is not appropriate to use ultrasound-based fat fraction values obtained from different vendors interchangeably.

CRITICAL RELEVANCE STATEMENT

Considering the substantial inter-platform variability in ultrasound-based fat fraction assessments, caution is imperative when interpreting and comparing fat fraction values obtained from different ultrasound platforms in clinical practice.

KEY POINTS

• Inter-platform reproducibility of ultrasound-based fat fraction examinations is important for its clinical application. • Significant variability across different ultrasound-based fat fraction examinations was observed. • Using ultrasound-based fat fraction values from different vendors interchangeably is not advisable.

Confounders of Ultrasound Attenuation Imaging in a Linear Probe Using the Canon Aplio i800 System: A Phantom Study

There have been studies showing attenuation imaging (ATI) with ultrasound as an approach to diagnose liver diseases such as steatosis or cirrhosis. So far, this technique has only been used on a convex probe. The goal of the study was to investigate the feasibility of ATI measurements using the linear array on a canon Aplio i800 scanner on certified phantoms. Three certified liver tissue attenuation phantoms were measured in five different positions using a linear probe. The effects of positioning and depth were explored and compared. The values were compared to the certified expected value for each phantom as well as the different measurement values for each measurement position. The ATI measurements on phantoms showed significant effect for the different probe positions and region of interest (ROI) depths. Values taken in the center with the probe perpendicular to the phantom were closest to certified values. Median values at 2.5-4.5 cm depth for phantoms 1 and 2 and 0.5-2.5 cm for phantom 3 were comparable with certified values. Measurements taken at a depth greater than 6 cm in any position were the least representative of the certified values (p-value < 0.01) and had the widest range throughout the different sessions. ATI measurements can be performed with the linear probe in phantoms; however, careful consideration should be given to depth dependency, as it can significantly affect measurement values. Remaining measurements at various depths within the 0.5-6.0 cm range showed deviation from the certified values of approximately 25%.

A prospective comparison of three ultrasound-based techniques in quantitative diagnosis of hepatic steatosis in NAFLD

PURPOSE

To investigate the correlation between different ultrasound attenuation-based techniques and to compare their diagnostic performances using proton magnetic resonance spectroscopy (1H-MRS) as a reference standard.

METHODS

Participants who had clinical suspicion of nonalcoholic fatty liver disease (NAFLD) were prospectively recruited. Each subject had ultrasound with attenuation imaging (ATI) or quantitative ultrasound including tissue attenuation imaging (TAI) and tissue scatter-distribution imaging (TSI), and controlled-attenuation parameter (CAP) and 1H-MRS if available. The technical success rates, intra-observer repeatabilities of attenuation and backscattering coefficient were evaluated. ATI, TAI and CAP were three attenuation-based techniques. Spearman coefficient was used to test correlations among them and 1H-MRS. In addition, the diagnostic performances of these parameters for detecting ≥ 5% or 10% hepatic steatosis were evaluated.

RESULTS

130 participants had ultrasound scanning. Among them, 67 had CAP and 48 had 1H-MRS. The technical success rates were all 100%. The intra-observer repeatabilities of them were also excellent (ICCs > 0.90) and AC-ATI correlated well with AC-TAI (r = 0.752). AC-ATI, AC-TAI showed moderate correlation with CAP, (rATI = 0.623, 95% CI 0.446-0.752, P < 0.001; rTAI = 0.573, 95% CI 0.377-0.720, P < 0.001). For correlation with 1H-MRS, ATI and TAI performed better than CAP(rATI = 0.587; rTAI = 0.712; r CAP = 0.485). The AUCs of ATI, TAI, TSI and CAP for detecting ≥ 5% hepatic steatosis were 0.883, 0.862, 0.870 and 0.868, respectively. The AUC improved to 0.907 when TAI and TSI were combined (P < 0.05). When detecting ≥ 10% hepatic steatosis, the AUCs were 0.855, 0.702, 0.822 and 0.838, respectively.

CONCLUSION

Different ultrasound attenuation-based techniques were well correlated and exhibited good diagnostic performances in quantitative diagnosis of hepatic steatosis, however, the threshold values were different. Combinations of multiple parameters may improve the diagnostic performance in detecting hepatic steatosis.

TRIAL REGISTRATION

The study has been registered online ( https://www.chictr.org.cn ; unique identifier: ChiCTR2300069459).

Prospective Comparison of Attenuation Imaging and Controlled Attenuation Parameter for Liver Steatosis Diagnosis in Patients With Nonalcoholic Fatty Liver Disease and Type 2 Diabetes

BACKGROUND & AIMS

Similarly to the controlled attenuation parameter (CAP), the ultrasound-based attenuation imaging (ATI) can quantify hepatic steatosis. We prospectively compared the performance of ATI and CAP for the diagnosis of hepatic steatosis in patients with type 2 diabetes and nonalcoholic fatty liver disease using histology and magnetic resonance imaging-proton density fat fraction (MRI-PDFF) as references.

METHODS

Patients underwent ATI and CAP measurement, MRI, and biopsy on the same day. Steatosis was classified as S0, S1, S2, and S3 on histology (<5%, 5%-33%, 33%-66%, and >66%, respectively) while the thresholds of 6.4%, 17.4%, and 22.1%, respectively, were used for MRI-PDFF. The area under the curve (AUC) of ATI and CAP was compared using a DeLong test.

RESULTS

Steatosis could be evaluated in 191 and 187 patients with MRI-PDFF and liver biopsy, respectively. For MRI-PDFF steatosis, the AUC of ATI and CAP were 0.86 (95% confidence interval [CI], 0.81-0.91) vs 0.69 (95% CI, 0.62-0.75) for S0 vs S1-S3 (P = .02) and 0.71 (95% CI, 0.64-0.77) vs 0.69 (95% CI, 0.61-0.75) for S0-S1 vs S2-S3 (P = .60), respectively. For histological steatosis, the AUC of ATI and CAP were 0.92 (95% CI, 0.87-0.95) vs 0.95 (95% CI, 0.91-0.98) for S0 vs S1-S3 (P = .64) and 0.79 (95% CI, 0.72-0.84) vs 0.76 (95% CI, 0.69-0.82) for S0-S1 vs S2-S3 (P = .61), respectively.

CONCLUSION

ATI may be used as an alternative to CAP for the diagnosis and quantification of steatosis, in patients with type 2 diabetes and nonalcoholic fatty liver disease.

CT-based methods for assessment of metabolic dysfunction associated with fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD), previously called metabolic nonalcoholic fatty liver disease, is the most prevalent chronic liver disease worldwide. The multi-factorial nature of MAFLD severity is delineated through an intricate composite analysis of the grade of activity in concert with the stage of fibrosis. Despite the preeminence of liver biopsy as the diagnostic and staging reference standard, its invasive nature, pronounced interobserver variability, and potential for deleterious effects (encompassing pain, infection, and even fatality) underscore the need for viable alternatives. We reviewed computed tomography (CT)-based methods for hepatic steatosis quantification (liver-to-spleen ratio; single-energy "quantitative" CT; dual-energy CT; deep learning-based methods; photon-counting CT) and hepatic fibrosis staging (morphology-based CT methods; contrast-enhanced CT biomarkers; dedicated postprocessing methods including liver surface nodularity, liver segmental volume ratio, texture analysis, deep learning methods, and radiomics). For dual-energy and photon-counting CT, the role of virtual non-contrast images and material decomposition is illustrated. For contrast-enhanced CT, normalized iodine concentration and extracellular volume fraction are explained. The applicability and salience of these approaches for clinical diagnosis and quantification of MAFLD are discussed.Relevance statementCT offers a variety of methods for the assessment of metabolic dysfunction-associated fatty liver disease by quantifying steatosis and staging fibrosis.Key points• MAFLD is the most prevalent chronic liver disease worldwide and is rapidly increasing.• Both hardware and software CT advances with high potential for MAFLD assessment have been observed in the last two decades.• Effective estimate of liver steatosis and staging of liver fibrosis can be possible through CT.

Noninvasive assessment of paediatric hepatic steatosis by using attenuation imaging

OBJECTIVES

To evaluate the diagnostic performance of attenuation imaging (ATI) with an ultrasound scanner (US) in the detection of paediatric hepatic steatosis.

METHODS

Ninety-four prospectively enrolled children were classified into normal weight and overweight/obese (OW/OB) groups according to body mass index (BMI). US findings, including hepatic steatosis grade and ATI value, were examined by two radiologists. Anthropometric and biochemical parameters were obtained, and nonalcoholic fatty liver disease (NAFLD) scores, including the Framingham steatosis index (FSI) and hepatic steatosis index (HSI), were calculated.

RESULTS

After screening, 49 OW/OB and 40 normal weight children aged 10-18 years old (55 males and 34 females) participated in this study. The ATI value was significantly higher in the OW/OB group than in the normal weight group and showed a significant positive correlation with BMI, serum alanine transferase (ALT), uric acid, and NAFLD scores (p < 0.05). In the multiple linear regression adjusted for age, sex, BMI, ALT, uric acid, and HSI, ATI showed a significant positive association with BMI and ALT (p < 0.05). The receiver operating characteristic analysis showed a very good ability of ATI to predict hepatic steatosis. The intraclass correlation coefficient (ICC) of interobserver variability was 0.92, and the ICCs of intraobserver variability were 0.96 and 0.93 (p < 0.05). According to the two-level Bayesian latent class model analysis, the diagnostic performance of ATI showed the best performance for predicting hepatic steatosis among other known noninvasive NAFLD predictors.

CONCLUSIONS

This study suggests that ATI is an objective and possible surrogate screening test for detecting hepatic steatosis in paediatric patients with obesity.

CLINICAL RELEVANCE STATEMENT

Using ATI as a quantitative tool in hepatic steatosis allows clinicians to estimate the extent of the condition and track changes over time. This is helpful for monitoring disease progression and guiding treatment decisions, especially in paediatric practice.

KEY POINTS

• Attenuation imaging is a noninvasive US-based method for the quantification of hepatic steatosis. • Attenuation imaging values were significantly higher in the OW/OB and steatosis groups than in the normal weight and no steatosis groups, respectively, with a meaningful correlation with known clinical indicators of nonalcoholic fatty liver disease. • Attenuation imaging performs better than other noninvasive predictive models used to diagnose hepatic steatosis.

Steatosis Quantification on Ultrasound Images by a Deep Learning Algorithm on Patients Undergoing Weight Changes

INTRODUCTION

A deep learning algorithm to quantify steatosis from ultrasound images may change a subjective diagnosis to objective quantification. We evaluate this algorithm in patients with weight changes.

MATERIALS AND METHODS

Patients (N = 101) who experienced weight changes ≥ 5% were selected for the study, using serial ultrasound studies retrospectively collected from 2013 to 2021. After applying our exclusion criteria, 74 patients from 239 studies were included. We classified images into four scanning views and applied the algorithm. Mean values from 3-5 images in each group were used for the results and correlated against weight changes.

RESULTS

Images from the left lobe (G1) in 45 patients, right intercostal view (G2) in 67 patients, and subcostal view (G4) in 46 patients were collected. In a head-to-head comparison, G1 versus G2 or G2 versus G4 views showed identical steatosis scores (R2 > 0.86, p < 0.001). The body weight and steatosis scores were significantly correlated (R2 = 0.62, p < 0.001). Significant differences in steatosis scores between the highest and lowest body weight timepoints were found (p < 0.001). Men showed a higher liver steatosis/BMI ratio than women (p = 0.026).

CONCLUSIONS

The best scanning conditions are 3-5 images from the right intercostal view. The algorithm objectively quantified liver steatosis, which correlated with body weight changes and gender.

Accuracy of attenuation coefficient measurement (ACM) for real-time ultrasound hepatic steatometry: Comparison of simulator/phantom data with magnetic resonance imaging proton density fat fraction (MRI-PDFF)

Objectives

To evaluate the accuracy and reproducibility of real time ultrasound (US) steatometry with the Attenuation Coefficient (AC) measurement in comparison with magnetic resonance imaging with proton density software module (MRI-PDFF).

Methods

This study was conducted between January 2021 and October 2021. The comparison of instrumental methods for assessing and grading hepatic steatosis using a multimodal phantom simulator of different fat and water ratios was performed. The study involved 3 radiological centers. The steatophantom was simultaneously investigated using three methods: magnetic resonance imaging with proton density software module (MRI-PDFF) and 128-slice multidetector computed tomography, and then by 2 different US scanner for steatosis assessment via Measurement Attenuation Imaging (ATI) ant Attenuation Coefficient Measurement (ACM).

Results

Modeling of hepatic steatosis using a series of phantom simulators allows evidence-based medicine to determine the diagnostic accuracy of the latest US techniques for steatosis. The ACM and ATI of both US systems on phantoms correlated well with each other and with MRI-PDFF and, thus, can provide good diagnostic value in the assessment of hepatic steatosis. MDCT was less sensitive to mild steatosis than AC and MRI-PDFF.

Conclusion

Measurement of ACs in US studies by devices from different vendors compared to other modalities of radiological imaging (MDCT and MRI-PDFF) by special phantoms is an accurate and promising method for noninvasive quantification of hepatic steatosis.

Development and validation of multivariable quantitative ultrasound for diagnosing hepatic steatosis

This study developed and validated multivariable quantitative ultrasound (QUS) model for diagnosing hepatic steatosis. Retrospective secondary analysis of prospectively collected QUS data was performed. Participants underwent QUS examinations and magnetic resonance imaging proton density fat fraction (MRI-PDFF; reference standard). A multivariable regression model for estimating hepatic fat fraction was determined using two QUS parameters from one tertiary hospital (development set). Correlation between QUS-derived estimated fat fraction(USFF) and MRI-PDFF and diagnostic performance of USFF for hepatic steatosis (MRI-PDFF ≥ 5%) were assessed, and validated in an independent data set from the other health screening center(validation set). Development set included 173 participants with suspected NAFLD with 126 (72.8%) having hepatic steatosis; and validation set included 452 health screening participants with 237 (52.4%) having hepatic steatosis. USFF was correlated with MRI-PDFF (Pearson r = 0.799 and 0.824; development and validation set). The model demonstrated high diagnostic performance, with areas under the receiver operating characteristic curves of 0.943 and 0.924 for development and validation set, respectively. Using cutoff of 6.0% from development set, USFF showed sensitivity, specificity, positive predictive value, and negative predictive value of 87.8%, 78.6%, 81.9%, and 85.4% for diagnosing hepatic steatosis in validation set. In conclusion, multivariable QUS parameters-derived estimated fat fraction showed high diagnostic performance for detecting hepatic steatosis.

Application of attenuation imaging for the detection of fatty liver in potential liver donors

PURPOSE

In living donor liver transplantation (LDLT), fatty liver adversely affects the outcome in donors or in recipients. The attenuation imaging (ATI) may be valuable for detecting fatty liver in potential liver donors. We aimed to investigate the role of ATI in screening liver donors.

METHOD

In this prospective study, potential liver donors undergoing MR examination, including proton MR spectroscopy (1H-MRS), were enrolled between January 2020 and December 2021 (study identifier: KCT0004486). All participants underwent ATI examinations to assess fatty liver disease. The reference standard for fatty liver was the hepatic fat fraction (HFF) on 1H-MRS, with 8% defined as the threshold for significant fatty liver. The correlation between attenuation coefficient (AC) and HFF was evaluated using Spearman's correlation coefficient. The diagnostic performance of AC for the detection of fatty liver disease was evaluated using receiver operating characteristic curve analysis.

RESULTS

A total of 102 participants (median age, 37 [range, 20-61] years; 65 men) were enrolled. Nineteen participants (18.6%) had significant fatty liver on 1H-MRS. AC significantly correlated with HFF on 1H-MRS (ρ = 0.674, P < 0.001), and was significantly higher in patients with HFF on 1H-MRS ≥ 8% than in patients with HFF on 1H-MRS < 8% (0.76 vs. 0.59, P < 0.001). By using the cutoff value of 0.66, the area under the curve of AC for the detection of significant fatty liver on 1H-MRS was 0.923 (95% confidence interval [CI]: 0.853-0.967), with sensitivity, specificity, and negative predictive values of 89.5% (95% CI: 66.9-98.7%), 83.1% (95% CI: 73.3-90.5%), and 97.2% (95% CI: 90.3-99.2%), respectively.

CONCLUSIONS

ATI showed good diagnostic performance with a high negative predictive value for the detection of significant fatty liver among potential liver donors.

Diagnostic Performance Comparison Between Ultrasound Attenuation Measurements From Right and Left Hepatic Lobes for Steatosis Detection in Non-alcoholic Fatty Liver Disease

RATIONALE AND OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is currently diagnosed by liver biopsy or MRI proton density fat fraction (MRI-PDFF) from left hepatic lobe (LTHL) and/or right hepatic lobe (RTHL). The objective of this study was to compare the diagnostic value of ultrasound attenuation coefficients (ACs) from RTHL and LTHL in detecting hepatic steatosis using biopsy or MRI-PDFF as a reference standard.

MATERIALS AND METHODS

Sixty-six patients with suspected NAFLD were imaged with an Aplio i800 ultrasound scanner (Canon Medical Systems, Tustin, CA). Five AC measurements from RTHL and LTHL were averaged separately and together to be compared with the reference standard.

RESULTS

Forty-seven patients (71%) were diagnosed with NAFLD. Mean ACs were significantly higher in fatty livers than non-fatty livers (RTHL: 0.73 ± 0.10 vs. 0.63 ± 0.07 dB/cm/MHZ; p < 0.0001, LTHL: 0.78 ± 0.11 vs. 0.63 ± 0.06 dB/cm/MHz; p < 0.0001, RTHL & LTHL: 0.76 ± 0.09 vs. 0.63 ± 0.05 dB/cm/MHz; p < 0.0001). Biopsy steatosis grades (n =31) were better correlated with the mean ACs of RTHL & LTHL (r = 0.72) compared to LTHL (r = 0.67) or RTHL (r = 0.61). Correlation between MRI-PDFF (n = 35) and mean ACs was better for LTHL (r = 0.69) compared to the RTHL & LTHL (r = 0.66) or RTHL (r = 0.45). Higher diagnostic accuracy was shown for the mean ACs of RTHL & LTHL (AUC 0.89, specificity 94%, sensitivity 78%) compared to LTHL (AUC 0.89, specificity 88%, sensitivity 82%) or RTHL (AUC 0.81, specificity 89%, sensitivity 68%).

CONCLUSION

Ultrasound ACs from RTHL and LTHL showed comparable diagnostic values in detection of hepatic steatosis with the highest diagnostic accuracy when they were averaged together.

Quantitative Diagnosis of Nonalcoholic Fatty Liver Disease with Ultrasound Attenuation Imaging in a Biopsy-Proven Cohort

RATIONALE AND OBJECTIVES

To evaluate the performance of attenuation imaging (ATI) based on ultrasound for detection of hepatic steatosis in patients with nonalcoholic fatty liver disease (NAFLD).

MATERIALS AND METHODS

This prospective study was approved by our institutional review board (B2021-092R). Written informed consent was obtained from all patients. This study included 60 patients who had clinical suspicion of NAFLD and were referred for liver biopsy after ATI and controlled attenuation parameter (CAP) examinations between September 2020 and December 2021. The histologic hepatic steatosis was graded. The area under curve (AUC) analysis was performed.

RESULTS

The success rate of the ATI examination was 100%. The intraobserver reproducibility of ATI was 0.981. The AUCs of ATI for detecting ≥S1, ≥S2, and S3 were 0.968 (cut-off value of 0.671 dB/cm/MHz), 0.911 (cut-off value of 0.726 dB/cm/MHz), and 0.766 (cut-off value of 0.757 dB/cm/MHz), respectively. The AUCs of CAP for detecting ≥S1, ≥S2, and S3 were 0.916 (cut-off value of 258.5 dB/m), 0.872 (cut-off value of 300.0 dB/m), and 0.807 (cut-off value of 315.0 dB/m), respectively. The diagnostic values showed no significant difference between ATI and CAP in detecting ≥S1, ≥S2, and S3 (P = .281, P = .254, and P = .330, respectively). The ATI had significant correlations with high-density lipoprotein cholesterol (P < .001), and with triglycerides (P = .015).

CONCLUSION

ATI showed good feasibility and diagnostic performance in the detection of varying degrees of hepatic steatosis in NAFLD patients.

A Comparative Study of Ultrasound Attenuation Imaging, Controlled Attenuation Parameters, and Magnetic Resonance Spectroscopy for the Detection of Hepatic Steatosis

OBJECTIVES

To investigate the methodology and clinical application of ultrasound attenuation imaging (ATI) and comparative analyze the diagnostic performance of ATI and controlled attenuation parameters (CAP) for detecting and grading hepatic steatosis.

METHODS

A total of 159 patients with NAFLD were prospectively enrolled. CAP and ATI examinations were performed within a week before proton magnetic resonance spectroscopy (¹ H-MRS). Ten liver attenuation coefficient (AC) measurements by ATI were obtained in each patient. The interclass correlation coefficients (ICCs) of the intraobserver consistencies and the ICCs between the median of the first two through the first nine measurements and all 10 measurements were calculated. The correlations between ¹ H-MRS, CAP, biological data, and ATI were evaluated. The significant factors associated with ATI and the diagnostic performance of ATI and CAP for detecting hepatic steatosis was evaluated.

RESULTS

The median value of AC for detecting hepatic steatosis was 0.831 dB/cm/MHz. For the intraobserver consistency of ATI, the ICC was 0.931. Compared with 10 measurements, a minimum of four ATI measurements was required. The correlation of AC with hepatic fat fraction (HFF) was significantly higher than that of CAP (0.603 vs 0.326, P = .0015). The HFF and triglyceride (TG) were the significant factors for the ATI. The area under the receiver operating characteristics (ROC) curves of ATI and CAP were 0.939 and 0.788 for detecting ≥10% hepatic steatosis; 0.751 and 0.572 for detecting >33% hepatic steatosis. The cutoff values of ATI and CAP were 0.697 dB/cm/MHz and 310 dB/m for detecting ≥10% hepatic steatosis; 0.793 dB/cm/MHz and 328 dB/m for detecting >33% hepatic steatosis. The sensitivity of ATI and CAP were 85.92% and 52.11% for detecting ≥10% hepatic steatosis; 87.50% and 82.14% for detecting >33% hepatic steatosis. The specificity of ATI and CAP were 94.12% and 100% for detecting ≥10% hepatic steatosis; 54.37% and 43.69% for detecting >33% hepatic steatosis.

CONCLUSIONS

ATI technology showed excellent intraobserver consistency and the optimal minimum number of ATI measurements was 4. ATI is a promising noninvasive, quantitative and convenient tool for assessing hepatic steatosis.

Ultrasound attenuation imaging: a reproducible alternative for the noninvasive quantitative assessment of hepatic steatosis in children

BACKGROUND

Pediatric hepatic steatosis is a global public health concern, as an increasing number of children are affected by this condition. Liver biopsy is the gold standard diagnostic method; however, this procedure is invasive. Magnetic resonance imaging (MRI)-derived proton density fat fraction has been accepted as an alternative to biopsy. However, this method is limited by cost and availability. Ultrasound (US) attenuation imaging is an upcoming tool for noninvasive quantitative assessment of hepatic steatosis in children. A limited number of publications have focused on US attenuation imaging and the stages of hepatic steatosis in children.

OBJECTIVE

To analyze the usefulness of ultrasound attenuation imaging for the diagnosis and quantification of hepatic steatosis in children.

MATERIAL AND METHODS

Between July and November 2021, 174 patients were included and divided into two groups: group 1, patients with risk factors for steatosis (n = 147), and group 2, patients without risk factors for steatosis (n = 27). In all cases, age, sex, weight, body mass index (BMI), and BMI percentile were determined. B-mode US (two observers) and US attenuation imaging with attenuation coefficient acquisition (two independent sessions, two different observers) were performed in both groups. Steatosis was classified into four grades (0: absent, 1: mild, 2: moderate and 3: severe) using B-mode US. Attenuation coefficient acquisition was correlated with steatosis score according to Spearman's correlation. Attenuation coefficient acquisition measurements' interobserver agreement was assessed using intraclass correlation coefficients (ICC).

RESULTS

All attenuation coefficient acquisition measurements were satisfactory without technical failures. The median values for group 1 for the first session were 0.64 (0.57-0.69) dB/cm/MHz and 0.64 (0.60-0.70) dB/cm/MHz for the second session. The median values for group 2 for the first session were 0.54 (0.51-0.56) dB/cm/MHz and 0.54 (0.51-0.56) dB/cm/MHz for the second. The average attenuation coefficient acquisition was 0.65 (0.59-0.69) dB/cm/MHz for group 1 and 0.54 (0.52-0.56) dB/cm/MHz for group 2. There was excellent interobserver agreement at 0.94 (95% CI 0.92-0.96). There was substantial agreement between both observers (κ = 0.77, with a P < 0.001). There was a positive correlation between ultrasound attenuation imaging and B-mode scores for both observers (r = 0.87, P < 0.001 for observer 1; r = 0.86, P < 0.001 for observer 2). Attenuation coefficient acquisition median values were significantly different for each steatosis grade (P < 0.001). In the assessment of steatosis by B-mode US, the agreement between the two observers was moderate (κ = 0.49 and κ = 0.55, respectively, with a P < 0.001 in both cases).

CONCLUSION

US attenuation imaging is a promising tool for the diagnosis and follow-up of pediatric steatosis, which provides a more repeatable form of classification, especially at low levels of steatosis detectable in B-mode US.

Non-Invasive Imaging Methods to Evaluate Non-Alcoholic Fatty Liver Disease with Fat Quantification: A Review

Hepatic steatosis without specific causes (e.g., viral infection, alcohol abuse, etc.) is called non-alcoholic fatty liver disease (NAFLD), which ranges from non-alcoholic fatty liver (NAFL) to non-alcoholic steatohepatitis (NASH), fibrosis, and NASH-related cirrhosis. Despite the usefulness of the standard grading system, liver biopsy has several limitations. In addition, patient acceptability and intra- and inter-observer reproducibility are also concerns. Due to the prevalence of NAFLD and limitations of liver biopsies, non-invasive imaging methods such as ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) that can reliably diagnose hepatic steatosis have developed rapidly. US is widely available and radiation-free but cannot examine the entire liver. CT is readily available and helpful for detection and risk classification, significantly when analyzed using artificial intelligence; however, it exposes users to radiation. Although expensive and time-consuming, MRI can measure liver fat percentage with magnetic resonance imaging proton density fat fraction (MRI-PDFF). Specifically, chemical shift-encoded (CSE)-MRI is the best imaging indicator for early liver fat detection. The purpose of this review is to provide an overview of each imaging modality with an emphasis on the recent progress and current status of liver fat quantification.

Non-invasive evaluation of liver steatosis with imaging modalities: New techniques and applications

In the world, nonalcoholic fatty liver disease (NAFLD) accounts for majority of diffuse hepatic diseases. Notably, substantial liver fat accumulation can trigger and accelerate hepatic fibrosis, thus contributing to disease progression. Moreover, the presence of NAFLD not only puts adverse influences for liver but is also associated with an increased risk of type 2 diabetes and cardiovascular diseases. Therefore, early detection and quantified measurement of hepatic fat content are of great importance. Liver biopsy is currently the most accurate method for the evaluation of hepatic steatosis. However, liver biopsy has several limitations, namely, its invasiveness, sampling error, high cost and moderate intraobserver and interobserver reproducibility. Recently, various quantitative imaging techniques have been developed for the diagnosis and quantified measurement of hepatic fat content, including ultrasound- or magnetic resonance-based methods. These quantitative imaging techniques can provide objective continuous metrics associated with liver fat content and be recorded for comparison when patients receive check-ups to evaluate changes in liver fat content, which is useful for longitudinal follow-up. In this review, we introduce several imaging techniques and describe their diagnostic performance for the diagnosis and quantified measurement of hepatic fat content.

Technical Acoustic Measurements Combined with Clinical Parameters for the Differential Diagnosis of Nonalcoholic Steatohepatitis

Background and aim: Diagnosing nonalcoholic steatohepatitis (NASH) is challenging. This study intended to explore the diagnostic value of multiple technical acoustic measurements in the diagnosis of NASH, and to establish a diagnostic model combining technical acoustic measurements with clinical parameters to improve the diagnostic efficacy of NASH. Methods: We consecutively enrolled 75 patients with clinically suspected nonalcoholic fatty liver disease (NAFLD) who underwent percutaneous liver biopsy in our hospital from June 2020 to December 2021. All cases underwent multiple advanced acoustic measurements for liver such as shear wave dispersion (SWD), shear wave speed (SWS), attenuation imaging (ATI), normalized local variance (NLV), and liver-kidney intensity ratio (Ratio) examination before liver biopsies. A nomogram prediction model combining the technical acoustic measurements and clinical parameters was established and the model is proposed to improve the diagnostic performance of NASH. Results: A total of 75 cases were included in this study. The classification of pathological grade for NASH was as follows: normal liver, (n = 15, 20%), nonalcoholic fatty liver (NAFL), (n = 44, 58.7%), and NASH, (n = 16, 21.3%). There were statistically significant differences in SWS (p = 0.002), acoustic coefficient (AC) (p = 0.018), NLV (p = 0.033), age (p = 0.013) and fasting blood glucose (Glu) (p = 0.049) between NASH and non-NASH. A nomogram model which includes SWS, AC, NLV, age and Glu was built to predict NASH, and the calibration curves showed good calibrations in both training and validation sets. The AUCs of the combined nomogram model for the training set and validation set were 0.8597 and 0.7794, respectively. Conclusion: There were statistically significant differences in SWS, AC, NLV, age and Glu between NASH and non-NASH. A nomogram model which includes SWS, AC, NLV, age and Glu was built to predict NASH. The predictive model has a higher diagnostic performance than a single factor model in the diagnosis of NASH and has good clinical application prospects.

Different Ultrasound Shear Wave Elastography Techniques as Novel Imaging-Based Approaches for Quantitative Evaluation of Hepatic Steatosis-Preliminary Findings

BACKGROUND

Modern ultrasound (US) shear-wave dispersion (SWD) and attenuation imaging (ATI) can be used to quantify changes in the viscosity and signal attenuation of the liver parenchyma, which are altered in hepatic steatosis. We aimed to evaluate modern shear-wave elastography (SWE), SWD and ATI for the assessment of hepatic steatosis.

METHODS

We retrospectively analyzed the US data of 15 patients who underwent liver USs and MRIs for the evaluation of parenchymal disease/liver lesions. The USs were performed using a multifrequency convex probe (1-8 MHz). The quantitative US measurements for the SWE (m/s/kPa), the SWD (kPa-m/s/kHz) and the ATI (dB/cm/MHz) were acquired after the mean value of five regions of interest (ROIs) was calculated. The liver MRI (3T) quantification of hepatic steatosis was performed by acquiring proton density fat fraction (PDFF) mapping sequences and placing five ROIs in artifact-free areas of the PDFF scan, measuring the fat-signal fraction. We correlated the SWE, SWD and ATI measurements to the PDFF results.

RESULTS

Three patients showed mild steatosis, one showed moderate steatosis and eleven showed no steatosis in the PDFF sequences. The calculated SWE cut-off (2.5 m/s, 20.4 kPa) value identified 3/4 of patients correctly (AUC = 0.73, p > 0.05). The SWD cut-off of 18.5 m/s/kHz, which had a significant correlation (r = 0.55, p = 0.034) with the PDFF results (AUC = 0.73), identified four patients correctly (p < 0.001). The ideal ATI (AUC = 0.53 (p < 0.05)) cut-off was 0.59 dB/cm/MHz, which showed a significantly good correlation with the PDFF results (p = 0.024).

CONCLUSION

Hepatic steatosis can be accurately detected using all the US-elastography techniques applied in this study, although the SWD and the SWE showed to be more sensitive than the PDFF.

Ultrasound-based hepatic fat quantification: current status and future directions

Non-alcoholic fatty liver disease (NAFLD) is a spectrum of disease from fatty accumulation (steatosis), necro-inflammation though to fibrosis. It is of increasing global prevalence as a hepatic manifestation of the metabolic syndrome. Although accurate histopathology and magnetic resonance imaging techniques for hepatic fat quantification exist, these are limited by invasiveness and availability, respectively. Ultrasonography is potentially ideal for assessing and monitoring hepatic steatosis given the examination is rapid and readily available. Traditional ultrasound methods include qualitative B-mode for imaging markers, such as increased hepatic parenchymal echogenicity compared to adjacent renal cortex are commonplace; however, there is acknowledged significant interobserver variability and they are suboptimal for detecting mild steatosis. Recently quantitative ultrasound metrics have been investigated as biomarkers for hepatic steatosis. These methods rely on changes in backscatter, attenuation, and speed of sound differences encountered in a steatotic liver. Prospective studies using quantitative ultrasound parameters show good diagnostic performance even at low steatosis grades and in NAFLD. This review aims to define the clinical need for ultrasound-based assessments of liver steatosis, to describe briefly the physics that underpins the various techniques available, and to assess the evidence base for the effectiveness of the techniques that are available commercially from various ultrasound vendors.

How to Identify Advanced Fibrosis in Adult Patients with Non-Alcoholic Fatty Liver Disease (NAFLD) and Non-Alcoholic Steatohepatitis (NASH) Using Ultrasound Elastography-A Review of the Literature and Proposed Multistep Approach

Non-alcoholic fatty liver disease (NAFLD), and its progressive form, non-alcoholic steatohepatitis (NASH), represent, nowadays, real challenges for the healthcare system. Liver fibrosis is the most important prognostic factor for NAFLD, and advanced fibrosis is associated with higher liver-related mortality rates. Therefore, the key issues in NAFLD are the differentiation of NASH from simple steatosis and identification of advanced hepatic fibrosis. We critically reviewed the ultrasound (US) elastography techniques for the quantitative characterization of fibrosis, steatosis, and inflammation in NAFLD and NASH, with a specific focus on how to differentiate advanced fibrosis in adult patients. Vibration-controlled transient elastography (VCTE) is still the most utilized and validated elastography method for liver fibrosis assessment. The recently developed point shear wave elastography (pSWE) and two-dimensional shear wave elastography (2D-SWE) techniques that use multiparametric approaches could bring essential improvements to diagnosis and risk stratification.

Quantitative Ultrasound Biomarkers to Assess Nonalcoholic Fatty Liver Disease

PURPOSE

To assess diagnostic performance of quantitative ultrasound (QUS) biomarkers in assessing hepatic steatosis.

METHODS

We prospectively recruited 125 participants (mean age 54 years) who underwent liver QUS, magnetic resonance imaging (MRI), and laboratory tests within 30 days in this IRB approved study. Based on MRI-proton density fat fraction (MRI-PDFF) and MRE, we divided 125 participants into normal liver, nonalcoholic fatty liver (NAFL) and liver fibrosis (≥F1) groups. We examined diagnostic performance of ultrasound attenuation coefficient (AC), normalized local variance (NLV), superb microvascular imaging-based vascularity index (SMI-VI), and shear wave velocity (SWV) for determining hepatic steatosis and fibrosis using area under receiver operating characteristic curve (AUC). We also analyzed correlations of QUS biomarkers to MRI using Spearman correlation coefficient.

RESULTS

We observed significant differences in AC, NLV, and SMI-VI among the three groups (22 participants with normal liver, 78 with NAFL, and 25 with liver fibrosis). AUC of AC, NLV, and SMI-VI for determining ≥ mild steatotic livers (MRI-PDFF ≥5%) was 0.95, 0.90, and 0.92, respectively. AUC of SWV for determining ≥ F1 liver fibrosis was 0.93. The correlation of MRI-PDFF was positive to AC (r = 0.91) and negative to NLV (r = -0.74), SMI-VI (r = -0.8) in NAFL group. There was a significant difference in regression slope of AC to MRI-PDFF in livers with and without ≥F1 (0.84 vs 0.91, P = .02).

CONCLUSIONS

QUS biomarkers have high sensitivity and specificity to determine and grade hepatic steatosis and detect liver fibrosis. The effect of liver fibrosis on the performance of QUS biomarkers in quantifying liver fat content warrants further investigation.

Real-world assessment of SmartExam, a novel FibroScan computational method: A retrospective single-center cohort study

BACKGROUND AND AIM

SmartExam is a novel computational method compatible with FibroScan that uses a software called SmartDepth and continuous controlled attenuation parameter measurements to evaluate liver fibrosis and steatosis. This retrospective study compared the diagnostic accuracy of conventional and SmartExam-equipped FibroScan for liver stiffness measurement (LSM).

METHODS

The liver stiffness and the associated controlled attenuation parameters of 167 patients were measured using conventional and SmartExam-Equipped FibroScan as well as reference methods like magnetic resonance elastography (MRE) and magnetic resonance imaging-based proton density fat fraction (MRI-PDFF) measurements to assess its diagnostic performance. M or XL probes were selected based on the probe-to-liver capsule distance for all FibroScan examinations.

RESULTS

The liver stiffness and controlled attenuation parameter (CAP) correlation coefficients calculated from conventional and SmartExam-equipped FibroScan were 0.97 and 0.82, respectively. Using MRE/MRI-PDFF as a reference and the DeLong test for analysis, LSM and the area under the receiver operating characteristic curve for CAP measured by conventional and SmartExam-equipped FibroScan showed no significant difference. However, the SmartExam-equipped FibroScan measurement (33.6 s) took 1.4 times longer than conventional FibroScan (23.2 s).

CONCLUSIONS

SmartExam has a high diagnostic performance comparable with that of conventional FibroScan. Because the results of the conventional and SmartExam-equipped FibroScan were strongly correlated, it can be considered useful for assessing the fibrosis stage and steatosis grade of the liver in clinical practice, with less variability but little longer measurement time compared with the conventional FibroScan.

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

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

Hepatic steatosis: Ultrasound assessment using attenuation imaging (ATI) with liver biopsy correlation

INTRODUCTION

Hepatic steatosis duration and severity are risk factors for liver fibrosis and cardiometabolic disease. We assessed the diagnostic accuracy of attenuation imaging (ATI), compared with histologic hepatosteatosis grading in adults with varied suspected liver pathologies.

METHODS

Liver biopsy was performed on 76 patients (51 women, 25 men) with non-malignant diffuse parenchymal liver disease, within 4 weeks of multiparametric liver ultrasound including attenuation imaging (ATI). Skin-liver capsule distance (SCD) and body mass index (BMI) were measured. Histologic steatosis was graded none (S0), mild (S1), moderate (S2) or severe (S3). We compared histology and sonographic parameters.

RESULTS

The median patient age was 50.5 (range 18-83) years and BMI 28.9 kg/m² (interquartile range 24.0-33.3). The distribution of histologic steatosis grade was S0 (44%), S1(17%), S2(30%) and S3(9%). Median ATI value for each biopsy steatosis grade was 0.60 (IQR: 0.52-0.65), 0.65 (IQR: 0.6-0.71), 0.83 (IQR: 0.74-0.90) and 0.90 (IQR: 0.82-1.01) dB/cm/MHz for S0, S1, S2 and S3, respectively. The AUC of ATI for detection of any steatosis (S1-S3) and moderate to severe steatosis (S2-S3) was 0.85 (95% CI: 0.75-0.91) and 0.91 (95% CI: 0.83-0.99) with cut-offs of 0.55 and 0.62 dB/cm/MHz. ATI threshold of 0.74 dB/cm/MHz was able to discriminate between S0-S1 and S2-3 with accuracy, CI and kappa statistic of 0.8889, 0.65-0.98 and 0.7534.

CONCLUSION

We found a good correlation between ATI and steatosis grade. The most accurate discrimination was between none to mild (S0-1) and moderate to severe (S2-3) steatosis.

Detection and quantification of a focal fat deposition in a liver undergoing multiple operations for neuroendocrine tumor disease using attenuation imaging: a case report

BACKGROUND

In patients with history of malignancy, new-onset liver lesions often present diagnostic challenges. We present the case of a patient with history of neuroendocrine tumor and new-onset echo-rich hepatic lesion, in whom attenuation imaging helped to make the diagnosis. Attenuation imaging is an ultrasound-based technique that allows for the quantification of hepatic fat content on the basis of a measurement of sound attenuation.

CASE PRESENTATION

We present the case of a 62-year-old Caucasian female patient who underwent pylorus-preserving pancreaticoduodenectomy Whipple surgery in 2004 for histologically well-differentiated neuroendocrine tumor with a proliferation rate of 3% of the pancreatic head. During the course, single liver metastases were resected in 2009, 2010, and 2013. In 2019, hemihepatectomy was performed when two liver metastases recurred. The liver metastases each showed a proliferation rate of 10% with vigorous expression of chromogranin A, synaptophysin, and somatostatin. The most recent follow-up examinations showed a normal chromogranin A value and the patient reported a good general condition. However, sonography revealed a blurred, echoic lesion in the liver. On contrast-enhanced sonography, the lesion showed identical behavior to the surrounding liver parenchyma. In the asymptomatic patient, liver biopsy did not seem to be indicated at the current time. Measurement of the attenuation coefficient by attenuation imaging showed a significantly higher measurement in the area of the echo-rich lesion than in the rest of the liver. The overall findings are consistent with focal fat deposition.

CONCLUSIONS

Attenuation imaging appears to be useful in the evaluation of unclear echo-rich liver lesions. In particular, primary non-malignant-appearing liver lesions that are unremarkable on abdominal contrast-enhanced ultrasound can be more accurately assessed.

Quantification of Hepatic Steatosis by Ultrasound: Prospective Comparison With MRI Proton Density Fat Fraction as Reference Standard

BACKGROUND. Multiple ultrasound platforms now provide quantitative measures of hepatic steatosis. One such measure is the ultrasound-derived fat fraction (UDFF), which combines attenuation and backscatter quantification. OBJECTIVE. The purpose of this study was to characterize agreement between UDFF and MRI proton-density fat fraction (PDFF) measurements. METHODS. This prospective cross-sectional study enrolled 56 overweight and obese adolescents and adults (age ≥ 16 years) who underwent investigational ultrasound (deep abdominal transducer) and MRI examinations of the liver during a single visit from August 2020 to October 2020. Ultrasound examinations included three UDFF acquisitions of five measurements each (15 measurements total), and an overall median of medians was computed (UDFF_overall). MRI examinations included three PDFF acquisitions with calculation of an overall median PDFF. Spearman rank-order correlation was computed between UDFF and MRI PDFF measurements. Intraclass correlation coefficients and Bland-Altman difference plots were used to assess agreement. ROC curves were used to assess diagnostic performance of UDFF for detecting MRI PDFF of 5.5% or more. RESULTS. Median participant age was 32.5 years (IQR, 24.0-39.0 years); 40 participants were female, and 16 were male. A total of 34 (60.7%) participants had an MRI PDFF of 5.5% or more. UDFF_overall was 10.5% (IQR, 5.0-20.0%); median MRI PDFF was 6.1% (IQR, 3.4-13.7%). UDFF_overall was positively associated with MRI PDFF (ρ, 0.82; p < .001; intraclass correlation coefficient, 0.84 [95% CI, 0.59-0.93]). Mean bias between UDFF and PDFF was 4.0% (95% limits of agreement, -7.9% to 15.9%), with similar bias if summarizing UDFF by the first five measurements (4.4%), first three measurements (4.4%), or first measurement (4.6%). UDFF_overall AUC was 0.90 (95% CI, 0.79-0.96) for MRI PDFF of 5.5% or more; AUC was not significantly different when it was based on the number of UDFF measurements (p = .11-.97 for all pairwise AUC comparisons). UDFF_overall cutoff of more than 5% had sensitivity of 94.1% and specificity of 63.6% for diagnosing MRI PDFF of 5.5% or more. CONCLUSION. Measurements of hepatic steatosis using UDFF show strong agreement with measurements by MRI PDFF. A UDFF_overall cutoff of more than 5% provides high AUC and sensitivity, albeit low specificity, for detection of MRI PDFF of 5.5% or more. CLINICAL IMPACT. UDFF may have a clinical role in detection of hepatic steatosis. A reduced number of individual measurements is likely sufficient for determining an overall UDFF value. TRIAL REGISTRATION. ClinicalTrials.gov: NCT04523584.

Ultrasound Methods for the Assessment of Liver Steatosis: A Critical Appraisal

The prevalence of the non-alcoholic fatty liver disease has reached major proportions, being estimated to affect one-quarter of the global population. The reference techniques, which include liver biopsy and the magnetic resonance imaging proton density fat fraction, have objective practical and financial limitations to their routine use in the detection and quantification of liver steatosis. Therefore, there has been a rising necessity for the development of new inexpensive, widely applicable and reliable non-invasive diagnostic tools. The controlled attenuation parameter has been considered the point-of-care technique for the assessment of liver steatosis for a long period of time. Recently, many ultrasound (US) system manufacturers have developed proprietary software solutions for the quantification of liver steatosis. Some of these methods have already been extensively tested with very good performance results reported, while others are still under evaluation. This manuscript reviews the currently available US-based methods for diagnosing and grading liver steatosis, including their classification and performance results, with an appraisal of the importance of this armamentarium in daily clinical practice.

Correlation between hepatorenal index and attenuation imaging for assessing hepatic steatosis

INTRODUCTION

Hepatic steatosis screening is required to assess high-risk populations, identify those for intervention, monitor response and prevent disease progression and complications. Liver biopsy and magnetic resonance imaging proton density fat fraction are current gold standards, but are limited by biopsy risk factors, patient tolerance and cost. Non-invasive, cost-effective, semi-quantitative and quantitative ultrasound assessment exists. The aim of this study was to assess the correlation between the semi-quantitative hepatorenal index (HRI) to assess hepatic steatosis using the quantitative attenuation imaging (ATI) as a reference standard, in adults with varied suspected liver pathologies.

METHODS

Data were collected prospectively between April 2019 and March 2020 at a tertiary institution on any patient >18 years referred to US assessment of suspected liver pathology. The only exclusion criteria were absent or invalid HRI or ATI measurements. Three hundred fifty eight patients were included.

RESULTS

There was a significant weak positive correlation between HRI and ATI (r = 0.351, P < 0.001) and between HRI steatosis grade (SG) and ATI SG (r = 0.329, P < 0.001), using previously established cut-off values. With ATI as the reference standard, there was no significant correlation between HRI and hepatic steatosis within steatosis grades, nor for no (SG = 0) or any (SG > 0) hepatic steatosis.

CONCLUSIONS

Our study in a typical heterogeneous clinical population suggests the semi-quantitative HRI is of limited use in hepatic steatosis imaging. As HRI is the objective measure of the subjective brightness (B)-mode assessment, this imaging feature may not be as reliable as previously thought. Quantitative ATI may be the preferred non-invasive technique for hepatic steatosis assessment.

Changing clinical management of NAFLD in Asia

Non-alcoholic fatty liver disease (NAFLD) has become the leading cause of chronic liver disease, affecting approximately 25% of the world's population. Recently, because of the sedentary lifestyle and overnutrition resulting from urbanisation, the burden of NAFLD has rapidly increased in many Asian countries. Currently, the prevalence of NAFLD in Asia is approximately 30%, as is the case in many Western countries. In Asia, the prevalence and presentation of NAFLD vary widely across regions because of the substantial diversity in race, socioeconomic status and living environment. Furthermore, the dual aetiology of fatty liver, particularly with viral hepatitis in Asia, makes it complex and challenging to manage. Because Asians are likely to have central adiposity and insulin resistance, approximately 7%-20% of non-obese Asians with body mass indexes of less than 25 kg/m² are estimated to have NAFLD. Accumulating evidence indicates that NAFLD is associated with various extrahepatic comorbidities such as cardiovascular disease, chronic kidney disease, malignancy, in addition to liver-specific complications. Therefore, NAFLD should be managed as a multisystem disease in conjunction with metabolic syndrome. Lifestyle modification remains the basis of NAFLD management, but few patients can achieve adequate weight loss and maintain it long term. While various pharmacological agents are in phase 3 trials for steatohepatitis, Asian patients are underrepresented in most trials. This article reviews the epidemiological trends, clinical features, optimal assessment and current management practices for NAFLD in Asia.

Feasibility of Ultrasound Attenuation Imaging for Assessing Pediatric Hepatic Steatosis

We investigated the feasibility of ultrasound attenuation imaging (ATI) for assessing pediatric hepatic steatosis. A total of 111 children and adolescents who underwent liver ultrasonography with ATI for suspected hepatic steatosis were included. Participants were classified into the normal, mild, or moderate−severe fatty liver group according to grayscale US findings. Associations between clinical factors, magnetic resonance imaging proton density fat fraction, steatosis stage and ATI values were evaluated. To determine the cutoff values of ATI for staging hepatic steatosis, areas under the curve (AUCs) were analyzed. Factors that could cause measurement failure with ATI were assessed. Of 111 participants, 88 had successful measurement results. Median ATI values were significantly increased according to steatosis stage (p < 0.001). Body mass index (BMI) was a significant factor for increased ATI values (p = 0.047). To differentiate fatty liver from normal liver, a cutoff value of 0.59 dB/cm/MHz could be used with an AUC value of 0.853. To differentiate moderate to severe fatty liver from mild fatty liver, a cutoff value of 0.69 dB/cm/MHz could be used with an AUC value up to 0.91. ATI can be used in children as an effective ultrasonography technique for quantifying and staging pediatric hepatic steatosis.

Diagnostic Performance of Attenuation to Stage Liver Steatosis with MRI Proton Density Fat Fraction as Reference: A Prospective Comparison of Three US Machines

Background US tools to quantify liver fat content have recently been made clinically available by different vendors, but comparative data on their accuracy are lacking. Purpose To compare the diagnostic performances of the attenuation parameters of US machines from three different manufacturers (vendors 1, 2, and 3) in participants who underwent liver fat quantification with the MRI-derived proton density fat fraction (PDFF). Materials and Methods From July 2020 to June 2021, consecutive participants with chronic liver disease were enrolled in this prospective single-center study and underwent MRI PDFF quantification (reference standard) and US on the same day. US was performed with two different machines from among three vendors assessed. Areas under the receiver operating characteristic curve (AUCs) for the staging of liver steatosis (MRI PDFF: ≥5.5% for grade ≥S1 and ≥15.5% for grade ≥S2) were calculated in test and validation samples and then compared between vendors in the study sample. Results A total of 534 participants (mean age, 60 years ± 13 [SD]; 320 men) were evaluated. Failure of measurements occurred in less than 1% of participants for all vendors. Correlation coefficients with the MRI PDFF were 0.71, 0.73, and 0.54 for the attenuation coefficients of vendors 1, 2, and 3, respectively. In the test sample, AUCs for diagnosis of steatosis grade S1 and higher and grade S2 and higher were 0.89 and 0.93 for vendor 1 attenuation, 0.88 and 0.92 for vendor 2 attenuation, and 0.79 and 0.79 for vendor 3 attenuation, respectively. In the validation sample, a threshold value of 0.65 for vendor 1 and 0.66 for vendor 2 yielded sensitivity of 77% and 84% and specificity of 78% and 85%, respectively, for diagnosis of grade S1 and higher. Vendor 2 attenuation had greater AUCs than vendor 3 attenuation (P = .001 and P = .003) for diagnosis of grade S1 and higher and grade S2 and higher, respectively, and vender 2 had greater AUCs for attenuation than vendor 1 for diagnosis of grade S2 and higher (P = .04). For all vendors, attenuation was not associated with liver stiffness (correlation coefficients <0.05). Conclusion To stage liver steatosis, attenuation coefficient accuracy varied among US devices across vendors when using MRI proton density fat fraction quantification as the reference standard, with some demonstrating excellent diagnostic performance and similar cutoff values. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Dubinsky in this issue.

Two-dimensional Shear-Wave Elastography and US Attenuation Imaging for Nonalcoholic Steatohepatitis Diagnosis: A Cross-sectional, Multicenter Study

Background Multiparametric US examination may have potential in the comprehensive evaluation of nonalcoholic fatty liver disease (NAFLD), but multicenter studies are lacking. Purpose To evaluate the diagnostic performance of multiparametric US with the attenuation coefficient (AC) from attenuation imaging (ATI) and liver stiffness (LS) and dispersion slope (DS) from two-dimensional (2D) shear-wave elastography (SWE) in a multicenter study of patients with NAFLD. Materials and Methods This prospective study enrolled consecutive participants between December 2019 and June 2021 with suspected nonalcoholic steatohepatitis (NASH) who were scheduled to undergo liver biopsy in five tertiary hospitals. Before the procedure, all participants underwent US with ATI and 2D SWE according to the study protocol. Multivariable linear regression analyses were performed to determine the significant determinant factors for AC, LS, and DS. Diagnostic performance was decided based on the areas under the receiver operating characteristic curve (AUCs). Results A total of 132 participants (median age, 38 years; IQR, 27-54 years; 69 women) were evaluated. Among the participant characteristics, including pathologic findings, demographic characteristics, body mass index, and serum markers, hepatic steatosis for AC (P < .001), lobular inflammatory activity for DS (P = .007), and both fibrosis (P = .01) and lobular inflammatory activity (P = .04) for LS were significant determinant factors. At histopathologic examination, 53 of the 132 participants (40.2%) had NASH. The risk score system obtained using unweighted sum of scores from AC and DS showed the best diagnostic performance in the detection of NASH (AUC = 0.94; 95% CI: 0.89, 0.98; P < .05 for all), as compared with serum markers or other US parameters alone (AUC ≤ 0.88). Conclusion US attenuation imaging and two-dimensional shear-wave elastography were useful for assessing hepatic steatosis, lobular inflammation, and fibrosis. The risk score system obtained using the attenuation coefficient and dispersion slope showed the best diagnostic performance fo r nonalcoholic steatohepatitis. cris.nih.go.kr no. KCT0004326 © RSNA, 2022 Online supplemental material is available for this article.

Ultrasound Shear Wave Elastography, Shear Wave Dispersion and Attenuation Imaging of Pediatric Liver Disease with Histological Correlation

Aim: To evaluate the feasibility of multiple ultrasound markers for the non-invasive characterization of fibrosis, inflammation and steatosis in the liver in pediatric patients. Materials and methods: The quantitative ultrasound measures shear wave elastography (SWE), shear wave dispersion (SWD) and attenuation imaging (ATI) were compared and correlated with percutaneous liver biopsies and corresponding measures in a control cohort. Results: The median age of the 32 patients was 12.1 years (range 0.1−17.9), and that of the 15 controls was 11.8 years (range: 2.6−16.6). Results: There was a significant difference in SWE values between histologic grades of fibrosis (p = 0.003), with a positive correlation according to the grade (r = 0.7; p < 0.0001). Overall, a difference in SWD values between grades of inflammation was found (p = 0.009) but with a lack of correlation (r = 0.1; p = 0.67). Comparing inflammation grades 0−1 (median:13.6 m/s kHz [min; max; 8.4; 17.5]) versus grades 2−3 (16.3 m/s kHz [14.6; 24.2]) showed significant differences between the groups (p = 0.003). In the 30 individuals with a steatosis score of 0, ATI was measured in 23 cases with a median value of 0.56 dB/cm/MHz. Conclusion: Comprehensive ultrasound analysis was feasible to apply in children and has the potential to reflect the various components of liver affection non-invasively. Larger studies are necessary to conclude to what extent these image-based markers can classify the grade of fibrosis, inflammation and steatosis.

Clinical evaluation of grayscale and linear scale hepatorenal indices for fatty liver quantification: a prospective study of a native Chinese population

BACKGROUND AND AIMS

Hepato-renal index (HRI) has been investigated extensively in various clinical studies. New linear scale HRI (LS-HRI) is proposed as an alternative to conventional grayscale HRI (GS-HRI) that suffers from lack of a widely accepted cut-off value for differentiation of fatty from normal livers. To investigate the diagnostic performance of conventional GS-HRI and new LS-HRI for a relatively large Chinese population with NAFLD using a well-established ultrasonographic fatty liver indicator (US-FLI) as the reference standard for steatosis grades.

MATERIALS AND METHODS

A total of 106 patients with various stages of NAFLD were prospectively enrolled. All ultrasound images for these patients were first acquired by a highly experienced ultrasound doctor and their US-FLI scores then obtained by the same doctor. Both GS-HRI and LS-HRI values were measured off-line by two additional ultrasound doctors. Four steatosis grades were determined from US-FLI scores for steatosis detection and staging.

RESULTS

Inter-observer agreements for both GS-HRI and LS-HRI were excellent with the respective concordance correlation coefficient (CCC) of 0.900 for GS-HRI and 0.822 for LS-HRI. A linear correlation to US-FLI for LS-HRI (R = 0.74) was substantially superior to that for GS-HRI (R = 0.46). LS-HRI had a sensitivity of 85.9% and a specificity of 96.3% to differentiate steatosis from the normal liver (AUROC: 95.5%) while GS-HRI had a sensitivity of 85.9% and a specificity of 92.6% to distinguish steatosis from the normal liver (AUROC: 94.7%).

CONCLUSIONS

Both GS-HRI and LS-HRI measurements are reproducible between two ultrasonographic clinicians and are evidently effective for steatosis detection.

Relationship Between Greyscale Ultrasound Grading of Hepatic Steatosis and Attenuation Imaging

Background

Non-alcoholic fatty liver disease (NAFLD) has been rising worldwide due to the rising public health threat of metabolic syndrome. Because non-alcoholic steatohepatitis can proceed to liver fibrosis and cirrhosis, early identification and monitoring are critical for management. For the examination of NAFLD, greyscale ultrasound has been frequently employed. A relatively new technique, attenuation imaging (ATI), can quantitatively evaluate and compute the attenuation coefficient (AC). Our goal was to evaluate the performance and cutoff values of attenuation imaging to identify hepatic steatosis. As a reference standard, greyscale ultrasound was employed.

Method

A total of 207 patients were assessed from June to November 2021 after getting informed consent. The association between ATI values and greyscale grading to diagnose hepatic steatosis was investigated, and the Statistical Package for the Social Sciences (SPSS) version 21 (IBM Corp., Armonk, NY, USA) was used to analyze the data. In the analysis, the Spearman correlation and area under the receiver operating characteristic curve (AUROC) tests were performed. Receiver operating characteristic curve analysis was also used to assess ATI’s diagnostic capability and cutoff values.

Result

The correlation between ATI values and hepatic steatosis grades on greyscale was statistically significant (p < 0.05). Greyscale grading and ATI levels have a correlation coefficient (r) of 0.85, indicating a strong association. Steatosis grades 1, 2, and 3 had threshold ATI values of 0.65, 0.73, and 0.96 dB/cm/MHz, respectively. According to greyscale, the diagnostic ability of ATI for steatosis grades 1, 2, and 3 were 0.948 (95% CI: 0.917-0.979), 0.978 (95% CI: 0.961-0.995), and 1.000 (95% CI: 1.000-1.000), respectively.

Conclusions

Attenuation imaging is a reliable method for identifying liver steatosis, with great performance and a strong association with the greyscale ultrasound.

Accuracy of attenuation imaging in the assessment of pediatric hepatic steatosis: correlation with the controlled attenuation parameter

PURPOSE

This study evaluated the accuracy of attenuation imaging (ATI) for the assessment of hepatic steatosis in pediatric patients, in comparison with the FibroScan vibration-controlled transient elastography controlled attenuation parameter (CAP).

METHODS

Consecutive pediatric patients referred for evaluation of obesity who underwent both ATI and FibroScan between February 2020 and September 2021 were included. The correlation between attenuation coefficient (AC) and CAP values was assessed using the Spearman test. The AC cutoff value for discriminating hepatic steatosis corresponding to a CAP value of 241 dB/m was calculated. Multivariable linear regression analysis was performed to estimate the strength of the association between AC and CAP. The diagnostic accuracy of AC cutoffs was estimated using the imperfect gold-standard methodology based on a two-level Bayesian latent class model.

RESULTS

Seventy patients (median age, 12.5 years; interquartile range, 11.0 to 14.0 years; male:female, 58:12) were included. AC and CAP showed a moderate-to-good correlation (ρ =0.646, P<0.001). Multivariable regression analysis affirmed the significant association between AC and CAP (P<0.001). The correlation was not evident in patients with a body mass index ≥30 kg/m2 (ρ=-0.202, P=0.551). Linear regression revealed that an AC cutoff of 0.66 dB/cm/MHz corresponded to a CAP of 241 dB/m (sensitivity, 0.93; 95% confidence interval [CI], 0.85 to 0.98 and specificity, 0.87; 95% CI, 0.56 to 1.00).

CONCLUSION

ATI showed an acceptable correlation with CAP values in a pediatric population, especially in patients with a body mass index <30 kg/m2. An AC cutoff of 0.66 dB/cm/MHz, corresponding to a CAP of 241 dB/m, can accurately diagnose hepatic steatosis.

Efficacy of B-mode ultrasound-based attenuation for the diagnosis of hepatic steatosis: a systematic review/meta-analysis

The accuracy of attenuation coefficients and B-mode ultrasound for distinguishing between S0 (healthy, < 5% fat) and S1-3 (steatosis ≥ 5%) livers compared to a controlled attenuation parameter is unclear. This meta-analysis aimed to comprehensively assess the diagnostic performance of B-mode ultrasound imaging for evaluating steatosis of ≥ 5%. We searched the PubMed, Embase, and Web of Science databases for studies on the accuracy of B-mode ultrasound for differentiating S0 from S1-3 in adults with chronic liver disease. A bivariate random-effects model was performed to estimate the pooled sensitivity, specificity, positive (PLR) and negative likelihood ratios (NLR), and diagnostic odds ratios (DORs). Subgroup analyses by attenuation coefficient, conventional B-mode ultrasound findings, and B-mode ultrasound findings without semi-quantification methods were performed. Liver steatosis was scored as follows: S0, < 5%; S1, 5-33%; S2, 33-66%; and S3, > 66%. Nineteen studies involving 3240 patients were analyzed. The pooled sensitivity and specificity of B-mode ultrasound for detecting S1 were 0.70 (95% confidence interval [CI], 0.63-0.77) and 0.86 (95% CI 0.82-0.89), respectively. The pooled PLR, NLR, and DOR were 4.90 (95% CI 3.69-6.51), 0.35 (95% CI 0.27- 0.44), and 14.1 (95% CI 8.7-23.0), respectively. The diagnostic accuracy was better in patients with attenuation coefficients (area under the curve [AUC], 0.89; sensitivity, 0.75; specificity, 0.86) than in those with conventional B-mode findings (AUC, 0.80; sensitivity, 0.59; specificity, 0.83). In particular, the diagnostic value was better when the attenuation coefficient guided by B-mode ultrasound was utilized. To screen patients with steatosis of ≥ 5%, attenuation coefficient should be used.

Shear wave elastography and shear wave dispersion imaging in primary biliary cholangitis-a pilot study

Background

Primary biliary cholangitis (PBC) is a chronic liver disease that can lead to liver fibrosis and cirrhosis. Two-dimensional shear wave elastography (2D-SWE) is a modern technique for fibrosis assessment. However, data regarding its performance in PBC is sparse. We aimed to characterize severity of liver disease in PBC patients using non-invasive 2D-SWE and the new methods of attenuation imaging (ATI) and shear wave dispersion imaging (SWD).

Methods

Twenty two PBC patients were examined with 2D-SWE, SWD and ATI, alongside established non-invasive fibrosis and steatosis assessment methods as well as liver function tests.

Results

Median 2D-SWE values were 1.48 m/s (range, 1.14-2.13 m/s) and 6.7 kPa (range, 3.8-14.7 kPa), respectively. Median SWD, ATI, transient elastography (TE) and controlled attenuation parameter (CAP) values were 13.9 m/s/kHz (range, 11.6-21 m/s/kHz), 0.57 dB/cm/MHz (range, 0.5-0.68 dB/cm/MHz), 7 kPa (range, 3.7-14.6 kPa), and 208 dB/m (range, 107-276 dB/m), respectively. 2D-SWE displayed a significant correlation with spleen length, platelet count, non-invasive fibrosis scores (FIB-4, APRI) and with TE. SWD correlated with alkaline phosphatase (ALP) levels, which is a prognostic marker in PBC.

Conclusions

Our findings add further evidence that 2D-SWE is a reliable method for fibrosis assessment in PBC. Even though the cohort size was small, the correlation of SWD with the prognostic marker ALP suggests a potentially valuable role of this new non-invasive method in evaluating liver disease activity in PBC.

Quantitative evaluation of hepatic steatosis using novel ultrasound technology normalized local variance (NLV) and its standard deviation with different ROIs in patients with metabolic-associated fatty liver disease: a pilot study

Purpose

The purpose of this study was to evaluate the diagnostic performance of novel ultrasound technology normalized local variance (NLV) and the standard deviation of NLV (NLV-SD) using different ROIs for hepatic steatosis in patients with metabolic-associated fatty liver disease (MAFLD) and to identify the factors that influence the NLV value and NLV-SD value, using pathology results as the gold standard.

Methods

We prospectively enrolled 34 consecutive patients with suspected MAFLD who underwent percutaneous liver biopsy for evaluation of hepatic steatosis from June 2020 to December 2020. All patients underwent ultrasound and NLV examinations. NLV values and NLV-SD values were measured using different ROIs just before the liver biopsy procedure.

Results

The distribution of hepatic steatosis grade on histopathology was 4/19/6/5 for none (< 5%)/ mild (5–33%)/ moderate (> 33–66%)/ and severe steatosis (> 66%), respectively. The NLV value with 50-mm-diameter ROI and NLV-SD value with 50-mm-diameter ROI showed a significant negative correlation with hepatic steatosis (spearman correlation coefficient: − 0.449, p = 0.008; − 0.471, p = 0.005). The AUROC of NLV (50 mm) for the detection of mild, moderate, and severe hepatic steatosis was 0.875, 0.735, and 0.583, respectively. The AUROC of NLV-SD (50 mm) for the detection of mild, moderate, and severe hepatic steatosis was 0.900, 0.745, and 0.603, respectively. NLV (50 mm) values and NLV-SD (50 mm) values between two readers showed excellent repeatability and the intraclass correlation coefficient (ICC) was 0.930 (p < 0.001) and 0.899 (p < 0.001). Hepatic steatosis was the only determinant factor for NLV value and NLV-SD value (p = 0.012, p = 0.038).

Conclusion

The NLV (50 mm) and NLV-SD (50 mm) provided good diagnostic performance in detecting the varying degrees of hepatic steatosis with great reproducibility. This study showed that the degree of steatosis was the only significant factor affecting the NLV value and NLV-SD value.

US Attenuation for Liver Fat Quantification: An AIUM-RSNA QIBA Pulse-Echo Quantitative Ultrasound Initiative

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, with an estimated prevalence of up to 30% in the general population and higher in people with type 2 diabetes. The assessment of liver fat content is essential to help identify patients with or who are at risk for NAFLD and to follow their disease over time. The American Institute of Ultrasound in Medicine-RSNA Quantitative Imaging Biomarkers Alliance Pulse-Echo Quantitative Ultrasound Initiative was formed to help develop and standardize acquisition protocols and to better understand confounding factors of US-based fat quantification. The three quantitative US parameters explored by the initiative are attenuation, backscatter coefficient, and speed of sound. The purpose of this review is to present the current state of attenuation imaging for fat quantification and to provide expert opinion on examination performance and interpretation. US attenuation methods that need further study are outlined.