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

Comparing ultrasound-derived fat fraction and MRI-PDFF for quantifying hepatic steatosis: a real-world prospective study

OBJECTIVE

To compare the agreement between ultrasound-derived fat fraction (UDFF) with magnetic resonance proton density fat fraction (MRI-PDFF) for quantification of hepatic steatosis and verify its reliability and diagnostic performance by comparing with MRI-PDFF as the reference standard.

METHODS

This prospective study included a primary analysis of 191 patients who underwent MRI-PDFF and UDFF from February 2023 to February 2024. MRI-PDFF were derived from three liver segment measurements with calculation of an overall median PDFF. UDFF was performed by two different sonographers for each of the six measurements, and the median was taken. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were used to assess agreement. Receiver operating characteristics (ROC) curves were used to evaluate the diagnostic performance of UDFF in detecting different degrees of hepatic steatosis.

RESULTS

A total of 176 participants were enrolled in the final cohort of this study (median age, 36.0 years; 82 men, 94 women). The median MRI-PDFF value was 11.3% (interquartile range (IQR) 7.5-18.9); 84.7% patients had a median MRI-PDFF value ≥ 6.4%. The median UDFF measured by different sonographers were 9.5% (IQR: 5.0-18.0) and 9.0% (IQR: 5.0-18.0), respectively. The interobserver agreement of UDFF measurement was excellent agreement (ICC = 0.951 [95% CI: 0.934-0.964], p < 0.001). UDFF was positively strongly correlated with MRI-PDFF with ICC of 0.899 (95% CI: 0.852-0.930). The Bland-Altman analysis showed high agreement between UDFF and MRI-PDFF measurements, with a mean bias of 1.7% (95% LOA, -8.7 to 12.2%). The optimal UDFF cutoff values were 5.5%, 15.5% and 17.5% for detecting MRI-PDFF at historic thresholds of 6.4%, 17.4%, and 22.1%, with AUC of 0.851, 0.952, and 0.948, respectively. The sensitivity was 79.2%, 87.5%, 88.9%, and specificity was 81.5%, 90.6%, 90.0%, respectively.

CONCLUSIONS

UDFF is a reliable and accurate method for quantification and classification of hepatic steatosis, with strong agreement to MRI-PDFF. The UDFF cutoff values of 5.5%, 15.5%, and 17.5% provide high sensitivity and specificity for the detection of mild, moderate, and severe hepatic steatosis, respectively.

KEY POINTS

Question Is ultrasound-derived fat fraction (UDFF) reliable for the quantitative detection of hepatic steatosis compared to MRI proton density fat fraction (MRI-PDFF)? Findings UDFF cutoff values of 5.5%, 15.5%, and 17.5% provided high sensitivity and specificity for the detection of mild, moderate, and severe hepatic steatosis, respectively. Clinical relevance UDFF is a reliable and accurate method for quantification and classification of hepatic steatosis, with strong agreement to MRI-PDFF and high reproducibility of liver fat content by different sonographers.

Attenuation Coefficient for Hepatic Steatosis Using a Single Ultrasound System: Associations of Measurement Parameters With Interoperator Agreement and Diagnostic Performance

Background: Clinical adoption of ultrasound attenuation coefficient (AC) measurements has been hindered by lack of uniform measurement protocol and a range of factors that may cause variability. Objective: To evaluate associations of ROI depth, ROI size, and confidence map threshold with interobserver agreement and diagnostic performance of ultrasound AC measurements in detecting and grading hepatic steatosis using MRI proton-density fat fraction (PDFF) as the reference standard. Methods: This prospective study enrolled adults with known steatosis or at risk for steatosis from October 2023 to August 2024. One of two operators obtained videos of AC acquisitions using a single ultrasound unit. Both operators independently reviewed all videos and placed circular ROIs to obtain AC measurements for all 24 possible combinations of four ROI depths (2.0, 2.5, 3.0, and 4.0 cm from liver capsule to ROI outer edge), three ROI sizes (3.0, 3.5, and 4.0 cm), and two confidence map thresholds (20% and 40%). Participants underwent MRI PDFF measurement as reference. Results: The analysis included 101 participants (mean age, 54.5±12.1 years; 62 female, 39 male). Interoperator agreement was excellent for all combinations (intraclass correlation coefficient: 0.92-0.98). AC measurements showed strongest correlations (Spearman rho, 0.81 and 0.80 for operators 1 and 2, respectively) with MRI PDFF at a ROI depth of 4.0 cm. The optimal combination considering correlations with MRI PDFF and AUC across steatosis grades included a depth of 4.0 cm, size of 4.0 cm, and threshold of 40%. This combination had AUC for detecting steatosis with grade >0, >1, and >2 for operator 1 of 0.93, 0.88, and 0.81, respectively, and operator 2 of 0.92, 0.86, and 0.81, respectively. However, accuracy for detecting steatosis (grade >0) was highest for the combination of depth of 3.0 cm, size of 4.0 cm, and threshold of 40% (operator 1, 90.1%; operator 2, 82.2%). Conclusion: AC measurements showed excellent interoperator agreement across parameter combinations. Correlations with MRI PDFF were strongest at a depth of 4.0 cm. Combinations yielding highest diagnostic performance were identified. Clinical Impact: These results will help determine a standardized optimal protocol for ultrasound AC measurements, facilitating clinical adoption for liver fat quantification.

Diagnostic Performance of Ultrasound-Based Liver Fat Quantification With Reference to Magnetic Resonance Imaging Proton Density Fat Fraction and Histology

PURPOSE

To investigate the diagnostic performance of ultrasound attenuation imaging technology (USAT) in the evaluation of hepatic steatosis using magnetic resonance imaging proton density fat fraction (MRI PDFF) and histology as reference standards.

METHODS

In this single-center, prospective study, the liver fat content of 117 potential liver donor candidates was assessed by USAT and MRI PDFF between April and August 2024. Intraoperative liver biopsy was performed in 47 liver donors. Cut-off values of 6%, 17%, 22%, and 5%, 33%, 66% were used for mild, moderate, and severe steatosis in MRI PDFF and histology, respectively. The correlation between USAT and MRI PDFF was evaluated using Spearman's rho technique. Receiver operating characteristic (ROC) analysis was performed for the diagnostic performance of USAT, and optimal USAT cut-off values for different grades of hepatosteatosis were obtained.

RESULTS

There was a very strong correlation between USAT and MRI PDFF (rho = 0.933, p < 0.001). For MRI PDFF values greater than 6%, the area under the curve (AUC) was 0.97 [95% confidence interval (CI): 0.93-0.99] (p < 0.001). USAT cut-off values for differentiating between different grades of liver steatosis were 0.57, 0.68, and 0.76 dB/cm/MHz for mild, moderate, and severe steatosis, with sensitivities of 88.9%, 90.0%, and 86.7%, respectively. For histologically confirmed steatosis greater than 5%, the AUC was 0.94 (95% CI: 0.83-0.99) (p < 0.001), with a cut-off of 0.56 dB/cm/MHz for 84.6% sensitivity.

CONCLUSION

USAT demonstrates excellent diagnostic accuracy in both the quantification and grading of hepatic steatosis.

Ultrasound evaluation of chronic liver disease

Chronic liver disease is a world-wide epidemic. Any etiology that causes inflammation in the liver will lead to chronic liver disease. Presently, the most common inciting factor worldwide is steatotic liver disease. Recent advances in ultrasound imaging provide a multiparametric ultrasound methodology of diagnosing, staging, and monitoring treatment of chronic liver disease. Elastography has become a standard of care technique for the evaluation of liver fibrosis. Quantitative ultrasound allows for determination of the degree of fatty infiltration of the liver. Portal hypertension is the most important factor in determination of liver decompensation. B-mode findings combined with Doppler, and elastography techniques provide qualitative and quantitative methods of determining clinically significant portal hypertension. A newer method using contrast enhanced ultrasound may allow for a non-invasive quantitative estimation of the portal pressures. This paper reviews the use of multiparametric ultrasound in the evaluation of chronic liver disease including conventional B-mode ultrasound, Doppler, elastography and quantitative ultrasound for estimation of liver fat. The recent guidelines are presented and advised protocols reviewed.

Ultrasound-guided attenuation parameter for identifying metabolic dysfunction-associated steatotic liver disease: a prospective study

PURPOSE

This study assessed the performance of the ultrasound-guided attenuation parameter (UGAP) in diagnosing and grading hepatic steatosis in patients with metabolic dysfunctionassociated steatotic liver disease (MASLD). Magnetic resonance imaging proton density fat fraction (MRI-PDFF) served as the reference standard.

METHODS

Patients with hepatic steatosis were enrolled in this prospective study and underwent UGAP measurements. MRI-PDFF values of ≥5%, ≥15%, and ≥25% were used as references for the diagnosis of steatosis grades ≥S1, ≥S2, and S3, respectively. Spearman correlation coefficients and area under the receiver operating characteristic curves (AUCs) were calculated.

RESULTS

Between July 2023 and June 2024, the study included 88 patients (median age, 40 years; interquartile range [IQR], 36 to 46 years), of whom 54.5% (48/88) were men and 45.5% (40/88) were women. Steatosis grades exhibited the following distribution: 22.7% (20/88) had S0, 50.0% (44/88) had S1, 21.6% (19/88) had S2, and 5.7% (5/88) had S3. The success rate for UGAP measurements was 100%. The median UGAP value was 0.74 dB/cm/MHz (IQR, 0.65 to 0.82 dB/ cm/MHz), and UGAP values were positively correlated with MRI-PDFF (r=0.77, P<0.001). The AUCs of UGAP for the diagnoses of ≥S1, ≥S2, and S3 steatosis were 0.91, 0.90, and 0.88, respectively. In the subgroup analysis, 98.4% (60/61) of patients had valid controlled attenuation parameter (CAP) values. UGAP measurements were positively correlated with CAP values (r=0.65, P<0.001).

CONCLUSION

Using MRI-PDFF as the reference standard, UGAP demonstrates good diagnostic performance in the detection and grading of hepatic steatosis in patients with MASLD.

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.

Multiparametric Ultrasound for Chronic Liver Disease

Diffuse liver disease is a substantial world-wide problem. With the combination of conventional ultrasound of the abdomen, fat quantification and elastography, appropriate staging of the patient can be assessed. This information allows for the diagnosis of steatosis and detection of fibrosis as well as prognosis, surveillance, and prioritization for treatment. With the potential for reversibility with appropriate treatment accurate assessment for the stage of chronic liver disease is critical.

Intersystem and Interoperator Agreement of US Attenuation Coefficient for Quantifying Liver Steatosis

Background The extent of liver steatosis can be assessed using US attenuation coefficient (AC) algorithms currently implemented in several US systems. However, little is known about intersystem and interoperator variability in measurements. Purpose To assess intersystem and interoperator agreement in US AC measurements for fat quantification in individuals with varying degrees of liver steatosis and to assess the correlation of each manufacturer's AC algorithm results with MRI proton density fat fraction (PDFF). Materials and Methods This prospective study was conducted at Southwoods Imaging, Youngstown, Ohio, September 30-October 1, 2023. Two operators independently obtained AC measurements using eight US systems equipped with an AC algorithm from different manufacturers. On the same day, MRI PDFF measurement was performed by a different operator. Correlation between US AC and MRI PDFF was assessed using a mixed-effects model. Agreement between systems and operators was evaluated using the intraclass correlation coefficient (ICC). Results Twenty-six individuals (mean age, 55.4 years ± 10.7 [SD]; 16 female participants) were evaluated. The correlation of US AC with MRI PDFF was high for five AC algorithms (r range, 0.70-0.86), moderate for two (r = 0.62 for both), and poor for one (r = 0.47). In pairwise comparisons, none of the pairs of systems achieved excellent agreement (overall ICC = 0.33 [95% CI: 0.15, 0.52]). One pair showed good agreement (ICC = 0.79 [95% CI: 0.66, 0.87]), eight pairs showed moderate agreement (ICC range, 0.50 [95% CI: 0.22, 0.69] to 0.73 [95% CI: 0.49, 0.85]), and 19 pairs showed poor agreement (ICC range, 0.11 [95% CI: -0.06, 0.37] to 0.48 [95% CI: 0.20, 0.67]). Interoperator agreement on AC value was excellent for the Samsung Medison algorithm (ICC = 0.90 [95% CI: 0.80, 0.96]), good for the Siemens Healthineers (ICC = 0.76 [95% CI: 0.54, 0.89]) and Canon Medical Systems (ICC = 0.76 [95% CI: 0.16, 0.92]) algorithms, and moderate for the remaining algorithms (ICC range, 0.50 [95% CI: 0.16, 0.73] to 0.74 [95% CI: 0.51, 0.88]). The mean AC value obtained by the two operators did not differ for any system except the system from Canon Medical Systems. Conclusion There was substantial variability in AC values obtained with different US systems, precluding interchangeability between systems for liver steatosis diagnosis and follow-up imaging. Interoperator agreement ranged from moderate to excellent. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Han in this issue.

Effects of Silybum marianum, Pueraria lobate, combined with Salvia miltiorrhiza tablets on non-alcoholic fatty liver disease in adults: A triple-blind, randomized, placebo-controlled clinical trial

BACKGROUND & AIMS

Several medicinal plant extracts have demonstrated hepatoprotective effects. However, data are scarce regarding their combined effects on non-alcoholic fatty liver disease (NAFLD). This study aimed to investigate the effects of tablets containing Silybum marianum, Pueraria lobata, and Salvia miltiorrhiza (SPS) on NAFLD progression in Chinese adults.

METHODS

In this randomized, triple-blind, placebo-controlled clinical trial, 121 NAFLD patients (60 female and 61 male), diagnosed via magnetic resonance imaging (MRI) and aged 18-65 years, were enrolled. Participants were randomly allocated to receive SPS tablets (n = 60; three tablets per dose, twice daily) or placebo (n = 61) for 24 weeks. Each SPS tablet contained approximately 23.0 mg of silybin, 11.4 mg of puerarin, and 10.9 mg of salvianolic acid. There were no differences in appearance, taste and odour between the SPS tablets and placebo manufactured by BYHEALTH Co., LTD (Guangzhou, China). The primary endpoints were changes in the liver fat content (LFC) and steatosis grade from baseline to 24 weeks. Secondary outcomes included changes in biomarkers/scores of liver fibrosis and steatosis, oxidative stress, inflammatory cytokines, alcohol metabolism, and glucose metabolism.

RESULTS

A total of 112 participants completed the research. The intention-to-treat results showed a trend toward reduction in both absolute LFC (-0.52%) and percentage of LFC (-4.57%) in the SPS group compared to the placebo group after 24 weeks, but these changes didn't reach statistical significance (p > 0.05). The SPS intervention (vs. placebo) significantly decreased hypersensitive C-reactive protein level (-6.76%) and increased aldehyde dehydrogenase activity (+18.1%) at 24 weeks post-intervention (all p < 0.05). Per-protocol analysis further supported these effects. This trial is registered at Clinical Trials.gov (NCT05076058).

CONCLUSION

SPS supplementation may have potential benefits in improving NAFLD, but further larger-scale trials are necessary to confirm these findings.

Assessing Quality of Ultrasound Attenuation Coefficient Results for Liver Fat Quantification

BACKGROUND/OBJECTIVES

Algorithms for quantifying liver fat content based on the ultrasound attenuation coefficient (AC) are currently available; however, little is known about whether their accuracy increases by applying quality criteria such as the interquartile range-to-median ratio (IQR/M) or whether the median or average AC value should be used.

METHODS

AC measurements were performed with the Aplio i800 ultrasound system using the attenuation imaging (ATI) algorithm (Canon Medical Systems, Otawara, Tochigi, Japan). Magnetic resonance imaging proton density fat fraction (MRI-PDFF) was the reference standard. The diagnostic performance of the AC median value of 5 measurements (AC-M) was compared to that of AC average value (AC-A) of 5 or 3 acquisitions and different levels of IQR/M for median values or standard deviation/average (SD/A) for average values were also analyzed. Concordance between AC-5M, AC-5A, and AC3A was evaluated with concordance correlation coefficient (CCC).

RESULTS

A total of 182 individuals (94 females; mean age, 51.2y [SD: 15]) were evaluated. A total of 77 (42.3%) individuals had S0 steatosis (MRI-PDFF < 6%), 75 (41.2%) S1 (MRI-PDFF 6-17%), 10 (5.5%) S2 (MRI-PDFF 17.1-22%), and 20 (11%) S3 (MRI-PDFF ≥ 22.1%). Concordance of AC-5A and AC-3A with AC-5M was excellent (CCC: 0.99 and 0.96, respectively). The correlation with MRI-PDFF was almost perfect. Diagnostic accuracy of AC-5M, AC-5A, and AC3A was not significantly affected by different levels of IQR/M or SD/A.

CONCLUSIONS

The accuracy of AC in quantifying liver fat content was not affected by reducing the number of acquisitions (from five to three), by using the mean instead of the median, or by reducing the IQR/M or SD/A to ≤5%.

Quantitative Ultrasound and Ultrasound-Based Elastography for Chronic Liver Disease: Practical Guidance, From the AJR Special Series on Quantitative Imaging

Quantitative ultrasound (QUS) and ultrasound-based elastography techniques are emerging as non-invasive effective methods for assessing chronic liver disease. They are more accurate than B-mode imaging alone and more accessible than MRI as alternatives to liver biopsy. Early detection and monitoring of diffuse liver processes such as steatosis, inflammation, and fibrosis play an important role in guiding patient management. The most widely available and validated techniques are attenuation-based QUS techniques and shear-wave elastography techniques that measure shear-wave speed. Other techniques are supported by a growing body of evidence and are increasingly commercialized. This review explains general physical concepts of QUS and ultrasound-based elastography techniques for evaluating chronic liver disease. The first section describes QUS techniques relying on attenuation, backscatter, and speed of sound. The second section discusses ultrasound-based elastography techniques analyzing shear-wave speed, shear-wave dispersion, and shear-wave attenuation. With an emphasis on clinical implementation, each technique's diagnostic performance along with thresholds for various clinical applications are summarized, to provide guidance on analysis and reporting for radiologists. Measurement methods, advantages, and limitations are also discussed. The third section explores developments in quantitative contrast-enhanced and vascular ultrasound that are relevant to chronic liver disease evaluation.

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.

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.

Quantitative US fat fraction for noninvasive assessment of hepatic steatosis in suspected metabolic-associated fatty liver disease

OBJECTIVES

To evaluate the agreement between quantitative ultrasound system fat fraction (USFF) and proton magnetic resonance spectroscopy (1H-MRS) and the diagnostic value of USFF in assessing metabolic-associated fatty liver disease (MAFLD).

METHODS

The participants with or suspected of MAFLD were prospectively recruited and underwent 1H-MRS, USFF, and controlled attenuation parameter (CAP) measurements. The correlation between USFF and 1H-MRS was assessed using Pearson correlation coefficients. The USFF diagnostic performance for different grades of steatosis was evaluated using receiver operating characteristic curve analysis (ROC) and was compared with CAP, visual hepatic steatosis grade (VHSG).

RESULTS

A total of 113 participants (mean age 44.79 years ± 13.56 (SD); 71 males) were enrolled, of whom 98 (86.73%) had hepatic steatosis (1H-MRS ≥ 5.56%). USFF showed a good correlation (Pearson r = 0.76) with 1H-MRS and showed a linear relationship, which was superior to the correlation between CAP and 1H-MRS (Pearson r = 0.61). The USFF provided high diagnostic performance for different grades of hepatic steatosis, with ROC from 0.84 to 0.98, and the diagnostic performance was better than that of the CAP and the VHSG. The cut-off values of the USFF were different for various grades of steatosis, and the cut-off values for S1, S2, and S3 were 12.01%, 19.98%, and 22.22%, respectively.

CONCLUSIONS

There was a good correlation between USFF and 1H-MRS. Meanwhile, USFF had good diagnostic performance for hepatic steatosis and was superior to CAP and VHSG. USFF represents a superior method for noninvasive quantitative assessment of MAFLD.

CRITICAL RELEVANCE STATEMENT

Quantitative ultrasound system fat fraction (USFF) accurately assesses liver fat content and has a good correlation with magnetic resonance spectroscopy (1H-MRS) for the assessment of metabolic-associated fatty liver disease (MAFLD), as well as for providing an accurate quantitative assessment of hepatic steatosis.

KEY POINTS

Current diagnostic and monitoring modalities for metabolic-associated fatty liver disease have limitations. USFF correlated well with 1H-MRS and was superior to the CAP. USFF has good diagnostic performance for steatosis, superior to CAP and VHSG.

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.

Liver Fat Quantification With Ultrasound: Depth Dependence of Attenuation Coefficient

OBJECTIVES

The primary aim was to estimate the influence of various depths on ultrasound attenuation coefficient (AC) of multiple vendors in the liver. The secondary aim was to evaluate the impact of region of interest (ROI) size on AC measurements in a subset of participants.

METHODS

This Institutional Review Board (IRB)-approved Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study was carried out in two centers using AC-Canon and AC-Philips algorithms and extracting AC-Siemens values from ultrasound-derived fat fraction algorithm. Measurements were performed positioning ROI upper edge (3 cm size) at 2, 3, 4, 5 cm from the liver capsule with AC-Canon and AC-Philips and at 1.5, 2, 3 cm with Siemens algorithm. In a subset of participants, measurements were obtained with 1 and 3 cm ROI size. Univariate and multivariate linear regression models and Lin's concordance correlation coefficient (CCC) were used for statistical analysis as appropriate.

RESULTS

Three different cohorts were studied. Sixty-three participants (34 females; mean age: 51 ± 14 years) were studied with AC-Canon, 60 (46 females; mean age: 57 ± 11 years) with AC-Philips, and 50 (25 females; 61 ± 13 years) with AC-Siemens. There was a decrease in AC values per 1 cm increase in depth in all. In multivariable analysis, the coefficient was -0.049 (-0.060; -0.038 P < .001) with AC-Canon, -0.058 (-0.066; -0.049 P < .001) with AC-Philips and -0.081 (-0.112; -0.050 P < .001) with AC-Siemens. AC values with 1 cm ROI were significantly higher than those obtained with 3 cm ROI at all depths (P < .001) but the agreement between AC values obtained with different ROI size was excellent (CCC 0.82 [0.77-0.88]).

CONCLUSIONS

There is depth dependence in AC measurement that affects results. A standardized protocol with fixed ROI's depth and size is needed.

Toward acquisition protocol standardization for estimating liver fat content using ultrasound attenuation coefficient imaging

PURPOSE

This study's primary aim was to assess factors affecting ultrasound attenuation coefficient (AC) measurement repeatability using the Canon ultrasound (US) system. The secondary aim was to evaluate whether similar results were obtained with other vendors' AC algorithms.

METHODS

This prospective study was performed at two centers from February to November 2022. AC was obtained using two US systems (Aplio i800 of Canon Medical Systems and Arietta 850 of Fujifilm). An algorithm combining AC and the backscatter coefficient was also used (Sequoia US System, Siemens Healthineers). To evaluate inter-observer concordance, AC was obtained by two expert operators using different transducer positions with regions of interest (ROIs) varying in terms of depth and size. Intra-observer concordance was evaluated on measurements performed intercostally, subcostally, and in the left liver lobe. Lin's concordance correlation coefficient was used.

RESULTS

Thirty-four participants (mean age, 49.4±15.1 years; 18 females) were studied. AC values progressively decreased with depth. The measurements in intercostal spaces on bestquality US images using a 3-cm ROI with its upper edge 2 cm below the liver capsule during breath-hold showed the highest intra-observer and inter-observer concordance (0.92 [95% confidence interval, 0.88 to 0.95] and 0.89 [0.82 to 0.96], respectively). Measurements in the left lobe showed the lowest intra-observer and inter-observer concordance (0.67 [0.43 to 0.90] and 0.58 [0.12 to 1.00], respectively). Intercostal space measurements also had the highest repeatability for the other two ultrasound systems.

CONCLUSION

AC values obtained in intercostal spaces on best-quality images using a 3-cm ROI placed with its top 2 cm below the liver capsule were highly repeatable.

Prospective study comparing hepatic steatosis assessment by magnetic resonance imaging and four ultrasound methods in 105 successive patients

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is becoming a major health problem, resulting in hepatic, metabolic and cardio-vascular morbidity.

AIM

To evaluate new ultrasonographic tools to detect and measure hepatic steatosis.

METHODS

We prospectively included 105 patients referred to our liver unit for NAFLD suspicion or follow-up. They underwent ultrasonographic measurement of liver sound speed estimation (SSE) and attenuation coefficient (AC) using Aixplorer MACH 30 (Supersonic Imagine, France), continuous controlled attenuation parameter (cCAP) using Fibroscan (Echosens, France) and standard liver ultrasound with hepato-renal index (HRI) calculation. Hepatic steatosis was then classified according to magnetic resonance imaging proton density fat fraction (PDFF). Receiver operating curve (ROC) analysis was performed to evaluate the diagnostic performance in the diagnosis of steatosis.

RESULTS

Most patients were overweight or obese (90%) and had metabolic syndrome (70%). One third suffered from diabetes. Steatosis was identified in 85 patients (81%) according to PDFF. Twenty-one patients (20%) had advanced liver disease. SSE, AC, cCAP and HRI correlated with PDFF, with respective Spearman correlation coefficient of -0.39, 0.42, 0.54 and 0.59 (P < 0.01). Area under the receiver operating characteristic curve (AUROC) for detection of steatosis with HRI was 0.91 (0.83-0.99), with the best cut-off value being 1.3 (Se = 83%, Sp = 98%). The optimal cCAP threshold of 275 dB/m, corresponding to the recent EASL-suggested threshold, had a sensitivity of 72% and a specificity of 80%. Corresponding AUROC was 0.79 (0.66-0.92). The diagnostic accuracy of cCAP was more reliable when standard deviation was < 15 dB/m with an AUC of 0.91 (0.83-0.98). An AC threshold of 0.42 dB/cm/MHz had an AUROC was 0.82 (0.70-0.93). SSE performed moderately with an AUROC of 0.73 (0.62-0.84).

CONCLUSION

Among all ultrasonographic tools evaluated in this study, including new-generation tools such as cCAP and SSE, HRI had the best performance. It is also the simplest and most available method as most ultrasound scans are equipped with this module.