Ultrasound elastography: is there a shear wave speed cutoff for pediatric liver fibrosis and inflammation?

Mechanical rheological model on the assessment of elasticity and viscosity in tissue inflammation: A systematic review

Understanding the extent of inflammation is crucial for early disease detection, monitoring disease progression, and evaluating treatment responses. Over the past decade, researchers have demonstrated the need to understand the extent of inflammation through qualitative or quantitative characterization of tissue viscoelasticity using different techniques. In this scientific review, an examination of research on the association between elasticity and Viscosity in diseases, particularly as tissue inflammation progresses, is conducted. A review of utilizing mechanical rheological models to characterize quantitative viscoelastic parameters of normal and inflamed tissues is also undertaken. Based on inclusion and exclusion criteria, we identified 14 full-text studies suitable for review out of 290 articles published from January 2000 to January 2024. We used PRISMA guidelines for the systematic review. In the review, three studies demonstrated the criterion used by the researchers in identifying the best rheological model. Eleven studies showed the clinical application of the rheological model in quantifying the viscoelastic properties of normal and pathological tissue. The review quantified viscoelastic parameters for normal and pathological tissue across various soft tissues. It evaluated the effectiveness of each viscoelastic property in distinguishing between normal and pathological tissue stiffness. Furthermore, the review outlined additional viscoelastic-related parameters for researchers to consider in future stiffness classification studies.

Dual elastography to discriminate adjacent stages of fibrosis and inflammation in chronic hepatitis B: A prospective multicenter study

BACKGROUND AND AIMS

To evaluate the diagnostic performance of dual elastography (dual-elasto) in continuous differentiation of liver fibrosis and inflammation in a large prospective cohort of patients with chronic HBV.

APPROACH AND RESULTS

Adults with positive HBsAg for at least 6 months were recruited from 12 medical centers. Participants underwent dual-elasto evaluations. Biopsy was performed 3 days after dual-elasto examination. Four logistic regression models were trained and strung together into series models. Decision trees based on the series models were performed to achieve continuous differentiation of liver fibrosis and inflammation. The influence of inflammation on the fibrosis stage was also evaluated. A total of 560 patients were included in the training set and 240 in the validation set. Areas under the receiver operating characteristic curve of the series model were 0.82, 0.86, 0.93, and 0.96 to predict ≥F1, ≥F2, ≥F3, and F4 in the validation set, which were significantly higher than those of serum markers and shear wave elastography (all p < 0.05), except for the ≥ F1 levels ( p = 0.09). The AUCs of the series model were 0.93, 0.86, 0.95, and 0.84 to predict inflammation stages ≥G1, ≥G2, ≥G3, and G4, respectively. Decision trees realized 5 continuous classifications of fibrosis and inflammation. Inflammation could enhance the mild fibrosis stage classification while showing limited influences on severe fibrosis or cirrhosis diagnosis.

CONCLUSIONS

Dual-elasto demonstrated high performance in the continuous discrimination of fibrosis and inflammation in patients with HBV and could be used to diagnose mild fibrosis without the influence of inflammation.

Shear Wave Elastography in the Differentiation of Nonfibrotic Versus Fibrotic Liver Disease in Children: A Prospective Study With Histological Correlation

To evaluate the diagnostic accuracy of ultrasound shear wave elastography (SWE) prospectively and to determine cutoff value for nonfibrotic liver tissue in children with suspected or established liver disease.

Methods

In 90 consecutive pediatric patients, standardized 2D-SWE was performed during general anesthesia and free breathing. Liver stiffness was estimated with SWE followed by a percutaneous biopsy from the corresponding area. SWE values were compared with histology with fibrosis scored according to Batts & Ludwig classification (grade 0-4 = F0-F4) and to hepatic biomarkers.

Results

Four patients with SWE interquartile range (IQR)/median ≥ 30% kPa were excluded. The remaining 86 children (59% males) had a mean age = 10.2 years (0.1-18). The distribution of individuals with median (min;max) SWE values (kPa) within each fibrosis grade were; F0[n = 10; 5.0(3.4;6.3)], F1[n = 24; 5.0(3.6;8.7)], F2[n = 32; 5.8(3.5;13.4)], F3[n = 12, 7.5(4.0;14.4)], and F4[n = 8; 12.5(6.6;21.0)]. There was a significant difference between fibrosis grades (0.03 > P < 0.002) except between F0 and F1 respectively between F1 and F2. The AuROC differentiating F0-1 from F2-4 was 0.77(95% CI: 0.67-0.87). A cutoff SWE value of ≤4.5 kPa yielded 90% sensitivity and 68% specificity to rule out significant fibrosis (F2-F4). Out of the 18 children (21%) with SWE value ≤4.5 kPa, 12 had grade F0-1 and 6 had F2, although including some confounders for increased SWE measurements as steatosis/hepatitis/cholestasis.

Conclusions

2D-SWE ultrasound can reliably distinguish no/mild (F0/F1) from moderate/severe (F2-F4) fibrosis in children with suspected/established liver disease with good sensitivity and acceptable specificity. Our results show that in pediatric patients, when the indication for biopsy is to rule out significant fibrosis, SWE can be considered an alternative.

Diagnostic accuracy of fibrosis tests in children with non-alcoholic fatty liver disease: A systematic review

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in children. Even at young age, it can progress to liver fibrosis. Given the drawbacks of liver biopsy, there is a need for non-invasive methods to accurately stage liver fibrosis in this age group. In this systematic review, we evaluate the diagnostic accuracy of non-invasive methods for staging liver fibrosis in children with NAFLD.

METHODS

We searched MEDLINE, Embase, Web of Science and the Cochrane Library, for studies that evaluated the performance of a blood-based biomarker, prediction score or imaging technique in staging liver fibrosis in children with NAFLD, using liver biopsy as the reference standard.

RESULTS

Twenty studies with a total of 1787 NAFLD subjects were included, which evaluated three prediction scores, five simple biomarkers, two combined biomarkers and six imaging techniques. Most studies lacked validation. Substantial heterogeneity of studies and limited available study data precluded a meta-analysis of the few fibrosis tests evaluated in more than one study. The most consistent accuracy data were found for transient elastography by FibroScan®, ELF test and ultrasound elastography, with an area under the receiver operating characteristics curve varying between 0.92 and 1.00 for detecting significant fibrosis.

CONCLUSION

Due to the lack of validation, the accuracy and clinical utility of non-invasive fibrosis tests in children with NAFLD remains uncertain. As studies have solely been performed in tertiary care settings, accuracy data cannot directly be translated to screening populations.

Elastography for Pediatric Chronic Liver Disease: A Review and Expert Opinion

In adults with chronic liver diseases, ultrasound and magnetic resonance shear wave elastography (SWE) can replace liver biopsy in several clinical scenarios. Several guidelines on the use of ultrasound SWE for the adult population have been published. However, the number of publications in the pediatric population is limited, and available guidelines on SWE do not specifically address pediatric chronic liver diseases. In this article, we review the literature on the use of SWE for pediatric chronic liver diseases and provide expert opinion on how to use SWE, both ultrasound and magnetic resonance techniques, in the pediatric population.

Liver and spleen elastography of dogs affected by brachycephalic obstructive airway syndrome and its correlation with clinical biomarkers

The purpose of this study is to determine whether the brachycephalic obstructive airway syndrome (BOAS) is correlated to alterations in liver and spleen elasticity. Forty-eight brachycephalic and 22 mesocephalic dogs were submitted to a BOAS functional assessment, laboratory tests, abdominal ultrasound and liver and spleen Acoustic Radiation Force Impulse (ARFI) elastography. Dogs clinically affected by BOAS had higher values of liver stiffness (p < 0.001) than healthy dogs: medial lobes (1.57 ± 0.37 m/s), left and right lateral lobes (1.54 ± 0.50 m/s, 1.23 ± 0.28 m/s, respectively) and caudate lobe (1.28 ± 0.42 m/s). Compared to the mesocephalic group, the brachycephalic group (BOAS clinically affected and unaffected dogs) had higher spleen (2.51 ± 0.45 m/s; p < 0.001) and liver stiffness (p < 0.001): medial lobes (1.53 ± 0.37 m/s), left and right lateral lobes (1.47 ± 0.47 m/s, 1.20 ± 0.30 m/s, respectively) and caudate lobe (1.23 ± 0.40 m/s). Principal component analysis explained 70% of the variances composed by liver stiffness increase, erythrocytes and alanine aminotransferase reduction. Brachycephalic dogs had higher spleen and liver stiffness and a subacute inflammatory state, which represent another BOAS systemic effect. Consequently, these dogs can be at higher risk of hepatic disorders compared with mesocephalic dogs, similarly to humans affected by sleep apnea syndrome.

Diagnosis of Acute Rejection of Liver Grafts in Young Children Using Acoustic Radiation Force Impulse Imaging

OBJECTIVE. Frequency of acute rejection (AR) after pediatric liver transplant remains high despite progress in immunosuppression. Liver biopsy (LB) is the reference standard for the diagnosis of AR despite its potential for morbidity. The purpose of our study was to evaluate the ability of acoustic radiation force impulse (ARFI) imaging to distinguish AR from other causes of short- and medium-term liver dysfunction and to identify liver transplant cases with normal liver function. MATERIALS AND METHODS. ARFI imaging was used to evaluate shear wave velocity (SWV) after liver transplant in young children. All pediatric liver grafts that had LB and ARFI examination between January 2014 and December 2017 were included in this retrospective study. Results of LB were compared with those of SWV. Collected data included age at biopsy and transplant, sex, weight, height, body mass index, interval between liver transplant and shear wave elastography and LB, kind of graft, type of donor, and diagnosis at transplant. ROC curve analysis was performed to assess the diagnostic performance of SWV. Optimal cutoff of SWV using ARFI imaging in predicting AR was identified using the Youden index. RESULTS. Statistical analysis was performed on 54 children; six of the original 60 were excluded because of confounding alterations or changes in outcome. Median SWV was higher in patients with AR (2.03 m/s; interquartile range [IQR], 1.80-2.45 m/s) compared with those with idiopathic hepatitis (1.33 m/s; IQR, 1.12-1.53 m/s), portal hypertension (1.42 m/s; IQR, 1.32-1.72 m/s), cholangitis (1.56 m/s; IQR, 1.07-1.62 m/s) or normal liver function (1.23 m/s; IQR 1.12-1.29 m/s) at protocol biopsies (all comparisons, p < 0.01). SWV higher than 1.73 m/s was predictive for AR (AUC, 0.966). SWV also showed good diagnostic accuracy in normal liver function (AUC, 0.791). ARFI imaging was not predictive for hepatitis (AUC, 0.402), portal hypertension (AUC, 0.556), or cholangitis (AUC, 0.420). CONCLUSION. ARFI imaging could be routinely used in place of LB in pediatric patients with liver dysfunction after liver transplant, restricting indication and risks of biopsy to selected cases.

Two-dimensional ultrasound shear wave elastography for identifying and staging liver fibrosis in pediatric patients with known or suspected liver disease: a clinical effectiveness study

BACKGROUND

Ultrasound shear wave elastography (SWE) measures liver stiffness noninvasively, but few studies have defined cutoff values for detecting liver fibrosis in pediatric patients using 2-D ultrasound SWE.

OBJECTIVE

To evaluate the diagnostic performance of 2-D ultrasound SWE and define cutoff values for liver fibrosis in pediatric patients, using Canon (Toshiba) Aplio ultrasound systems.

MATERIALS AND METHODS

This was an institutional review board-approved retrospective study of patients (≤18 years old) who had undergone both liver 2-D ultrasound SWE and percutaneous liver biopsy within 6 months. Liver biopsies were staged using the METAVIR (fibrosis) scoring system. Continuous data were compared using the Mann-Whitney U test. Receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic performance.

RESULTS

Forty-six patients, with a median age of 11.5 years (interquartile range: 8.0-14.3 years), were included. Twenty-three patients were male (50%). Twenty-seven patients had a METAVIR fibrosis score of F0-1, and 19 patients had a score of F2-4. For differentiating METAVIR F0-1 from F2--4, the area under the ROC (AuROC) was 0.75 (95% confidence interval [CI]: 0.60-0.90). A cutoff of >1.89 m/s yielded sensitivity of 73.7% (95% CI: 51.2-88.2) and specificity of 77.8% (95% CI: 59.2-89.4). For the subset of patients without histological hepatic steatosis (n=35), the AuROC was 0.86 (95% CI: 0.71-1.0). The same cutoff of >1.89 m/s yielded a sensitivity of 80.0% (95% CI: 54.8-93.0) and specificity of 95.0% (95% CI 76.4-99.7).

CONCLUSION

Two-dimensional ultrasound SWE distinguishes patients with no/mild fibrosis from those with moderate/severe fibrosis with good sensitivity and specificity. Diagnostic performance is comparable to that published for magnetic resonance elastography and is likely adversely impacted by steatosis.

Shear wave elastography correlates with liver fibrosis scores in pediatric patients with liver disease

BACKGROUND

While liver biopsy remains the gold standard, given the procedure risks and sampling errors, there is a need for reliable noninvasive biomarkers of hepatic fibrosis.

OBJECTIVE

Determine the accuracy of two-dimensional shear wave elastography (2-D SWE) in predicting the histological severity of liver fibrosis in pediatric patients with known or suspected liver disease.

MATERIALS AND METHODS

Subjects 0-18 years old with known or suspected liver disease and liver biopsy within 30 days (n=70) were included. Comparisons by 2-D SWE were made to a control group (n=79). Two-dimensional SWE was performed using the GE LOGIQ E9 system. Liver biopsy specimens were scored according to METAVIR and Ishak scoring systems using Spearman's Rho correlation. Receiver operator characteristic (ROC) analysis, Kruskal-Wallis and Mann-Whitney U tests were conducted.

RESULTS

Control group median 2-D SWE measurements were lower than in subjects with any degree of liver fibrosis (P<0.001). Those with METAVIR F0 and Ishak 0 scores had significantly lower median 2-D SWE measurements (1.35 m/s; 1.36 m/s) than those with more advanced liver disease (F1-F3: 1.49-1.62 m/s; 1-4: 1.45-1.63 m/s) (P<0.05 for all), whereas the 2-D SWE in the higher scores were similar. Results did not differ between METAVIR and Ishak scores for any degree of fibrosis. Fibrosis scores moderately correlated with median 2-D SWE measurements (r_s=0.43). The area under the curve for F1 compared to combined control/F0 was 0.89 (95% confidence interval [CI] 0.83-0.95; P<0.001) with sensitivity of 94.6% and specificity of 78.6%. Results for Ishak score 1 were similar. The ideal cutoff value for identifying fibrosis was determined to be 1.29 m/s.

CONCLUSION

The liver 2-D SWE measurements correlated with the histological liver fibrosis scores, regardless of the histopathological scoring system, although 2-D SWE was better at identifying patients with early fibrosis, not at distinguishing among the individual fibrosis levels. Two-dimensional SWE using the GE LOGIQ US system is useful for identifying pediatric patients at risk for liver fibrosis.

Patchy echogenicity of the liver in patients with chronic hepatitis B does not indicate poorer elasticity

Purpose

This study was conducted to investigate whether the presence of patchy echogenicity in the liver of patients with chronic hepatitis B (CHB) is predictive of liver stiffness.

Methods

A total of 200 CHB patients with and without patchy echogenicity of the liver were assigned to two groups, with 100 patients in each group, and 32 of them underwent liver biopsy. Additionally, 80 healthy subjects, 100 inactive HBV carriers, and 100 patients with decompensated hepatic cirrhosis were assigned to the control groups. Laboratory tests and clinical data were collected, and shear wave velocity (SWV) of the liver was measured for all 480 subjects.

Results

The median SWV in patients with a normal liver, inactive hepatitis B virus carriers, CHB patients with and without patchy echogenicity, and decompensated hepatic cirrhosis were 1.07 m/sec, 1.08 m/sec, 1.16 m/sec, 1.16 m/sec, and 2.02 m/sec, respectively; there was no significant difference in SWV values between CHB patients with patchy echogenicity and those without patchy echogenicity. Furthermore, among CHB patients with and without patchy echogenicity, no significant difference in SWV was found according to fibrosis stage.

Conclusion

The presence of patchy echogenicity of the liver does not indicate a higher degree of liver stiffness.

Liver Ultrasound Elastography: An Update to the World Federation for Ultrasound in Medicine and Biology Guidelines and Recommendations

The World Federation for Ultrasound in Medicine and Biology has produced these guidelines for the use of elastography techniques in liver diseases. For each available technique, the reproducibility, results and limitations are analyzed, and recommendations are given. This set of guidelines updates the first version, published in 2015. Since the prior guidelines, there have been several advances in technology. The recommendations are based on the international published literature, and the strength of each recommendation is judged according to the Oxford Centre for Evidence-Based Medicine. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of liver diseases.

Quantitative Evaluation of Denervated Muscle Atrophy with Shear Wave Ultrasound Elastography and a Comparison with the Histopathologic Parameters in an Animal Model

This study explored the efficacy of shear wave ultrasound elastography (SWUE) for quantitative evaluation of denervated muscle atrophy in a rabbit model. The elastic modulus of the triceps surae muscle was measured with SWUE and compared with histopathologic parameters at baseline and at various post-denervation times (2, 4 and 8 wk) with 10 animals in each group. Our results revealed that the elastic modulus of denervated muscle was significantly lower at 2 wk but higher at 8 wk compared with that at the baseline (p <0.05), and no significant difference was found between the elastic modulus at 4 wk and that at the baseline (p > 0.05). The wet-weight ratio and the muscle fiber cross-sectional area of the denervated muscle decreased gradually during the 8 wk post-denervation together with a gradual increase of the collagen fiber area (p <0.05). In conclusion, SWUE was useful for quantitative evaluation of muscle denervation. The decreased elastic modulus might be an early sign of denervated muscle atrophy.

Role of Point Shear Wave Elastography in the Determination of the Severity of Fibrosis in Pediatric Liver Diseases With Pathologic Correlations

OBJECTIVES

Our aims in this study were as follows: (1) to determine the cutoff value that can distinguish between advanced liver fibrosis and normal liver tissue for two different elastographic techniques; (2) to determine the cutoff value that can distinguish mild liver fibrosis from normal liver tissue for the techniques; and (3) to assess tissue stiffness in nonalcoholic fatty liver disease (NAFLD).

METHODS

Seventy-five patients assessed for liver biopsy on the same day were evaluated by point shear wave elastography. Thirty-one healthy children and 11 children with NAFLD were also evaluated. A 9L4 transducer with Virtual Touch quantification (VTQ) and Virtual Touch imaging and quantification (VTIQ) modes (Siemens Medical Solutions, Mountain View, CA) was used for quantification.

RESULTS

The shear wave speed of the patients with NAFLD was higher than that of the control group. The only predictive factor for VTQ and VTIQ was the histologic fibrosis score (model-adjusted R²  = 0.56 for VTQ and 0.75 for VTIQ). Shear wave speed cutoffs were 1.67 m/s for VTQ and 1.56 m/s for VTIQ in detecting fibrosis or inflammation and 2.09 m/s for VTQ and 2.17 m/s for VTIQ in discriminating children with low and high histologic liver fibrosis scores.

CONCLUSIONS

The VTQ and VTIQ values reveal high-grade histopathologic fibrosis and have high success rates when distinguishing high- from low-grade fibrosis. However, they have limited success rates when differentiating low-grade fibrosis from normal liver tissue.