Two-dimensional Shear Wave Elastography with Propagation Maps for the Assessment of Liver Fibrosis and Clinically Significant Portal Hypertension in Patients with Chronic Liver Disease: A Prospective Study

Shear Wave Ultrasonographic Elastography in Pediatric Spleens and Its Role in Differential Diagnosis

Shear wave elastography (SWE) has become popular in clinical practice for many diseases. However, there is not adequate research on spleen-related diseases. This study aimed to investigate the potential of quantitative values obtained through SWE in evaluating spleen pathologies in the pediatric population and to demonstrate its performance to differentiate splenomegaly-related diseases. The research group retrospectively included children with pathological diagnoses related to the spleen from November 2016 to April 2021, and they were categorized into three groups, including portal hypertension (PH), benign lymphoid hyperplasia (BLH), and malignant infiltration (MI). Spleen sizes and parenchymal stiffness were also calculated for each group. Subsequently, mean spleen stiffness in each group was compared with normal values within the same age group. In total, 2781 children (1379 children for the study group; 1402 children for the control group) were enrolled in the study. The highest stiffness was observed in the PH group, which is statistically higher than others (p < 0.05). Although the mean spleen stiffness in the group with BLH was higher than the control and MI group, the difference was not statistically significant (p = 0.08). The mean stiffness in the group with MI was significantly lower than both the control group (p = 0.005) and PH (p = 0.01). In conclusion, using SWE in the differential diagnosis of etiologies causing splenomegaly could make an important contribution.

Ultrasound shear wave elastography for the evaluation of renal pathological changes in adult patients

OBJECTIVE

Many studies have conflicting findings in using shear wave elastography (SWE) to assess renal fibrosis. This study reviews the use of SWE to evaluate pathological changes in native kidneys and renal allografts. It also tries to elucidate the confounding factors and care taken to ensure the results are consistent and reliable.

METHODS

The review was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Literature search was conducted in Pubmed, Web of Science and Scopus database up to 23 October 2021. To evaluate risk and bias applicability, the Cochrane risk-of bias tool and GRADE was used. The review was registered under PROSPERO CRD42021265303.

RESULTS

A total of 2921 articles were identified. 104 full texts were examined and 26 studies included in systematic review. 11 studies performed on native kidneys and 15 studies on transplanted kidney. A wide range of impact factors was found that affect the accuracy of SWE of renal fibrosis in adult patients.

CONCLUSIONS

Compared to point SWE, two-dimensional SWE with elastogram could enable better selection of the region of interest in kidneys, leading to reproducible results. Tracking waves were attenuated as the depth from skin to region of interest increased, therefore, SWE is not recommended for overweight or obese patients. Variable transducer forces might also affect SWE reproducibility, thus, training of operators to ensure consistent operator-dependent transducer forces may be helpful.

ADVANCES IN KNOWLEDGE

This review provides a holistic insight on the efficiency of using SWE in evaluating pathological changes in native and transplanted kidneys, thereby contributing to the knowledge of its utilisation in clinical practice.

Network Meta-Analysis: Noninvasive Imaging Modalities for Identifying Clinically Significant Portal Hypertension

BACKGROUND

Although measurement of the hepatic venous pressure gradient (HVPG) is the current reference standard for obtaining portal venous pressures, several noninvasive imaging-based modalities have been proposed as alternatives.

AIMS

We performed a systematic review and meta-analysis to compare the diagnostic accuracy of noninvasive imaging approaches for identifying clinically significant portal hypertension (CSPH).

METHODS

Two independent reviewers conducted a literature search of PubMed, SCOPUS, and the Cochrane Library from inception until January 5, 2021. The following imaging modalities were compared to HVPG: computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance elastography, ultrasound, transient elastography (TE), shear wave elastography (SWE), acoustic radiation force impulse (ARFI) imaging, contrast-enhanced ultrasound (CEUS), and subharmonic-aided pressure estimation (SHAPE). Sensitivity, specificity, diagnostic odds ratio (DOR), and area under the curve (AUC) for summary receiver operating characteristic were calculated using both frequentist random effects and Bayesian network meta-analytic approaches.

RESULTS

We analyzed 45 studies of 5678 patients. A broad overlapping confidence interval (CI) of DOR was observed among different imaging modalities: ARFI (30.5; 95% CI 12.7-73.3), CEUS and SHAPE (21.1; 95% CI 6.4-69.8), TE of liver stiffness (21.1; 95% CI 13.3-33.5), CT and MRI (13.7; 95% CI 7.40-25.4), SWE of liver stiffness (10.5; 95% CI 5.2-21.1), and ultrasound (9.5; 95% CI 4.9-18.4). The AUC of all imaging methods exceeded 0.8, indicating very good performance. At a cutoff of 80% specificity, TE, CEUS, and SHAPE exceeded 80% sensitivity.

CONCLUSION

Overall, noninvasive imaging modalities perform well for identifying CSPH. Clinicians should consider these noninvasive and cost-efficient tests when diagnosing CSPH.

Staging Chronic Hepatitis B Related Liver Fibrosis with a Fractional Order Calculus Diffusion Model

RATIONALE AND OBJECTIVES

Accurately staging liver fibrosis is of great clinical significance. We aimed to evaluate the clinical potential of the non-Gaussian fractional order calculus (FROC) diffusion model in staging liver fibrosis.

MATERIALS AND METHODS

A total of 82 patients with chronic hepatitis B (CHB) were included in this prospective study. Diffusion weighted imaging (DWI)-derived parameters including the diffusion coefficient (D), fractional order parameter (β) and microstructural quantity (μ) sourced from FROC-DWI, and apparent diffusion coefficient (ADC) derived from mono-exponential DWI, as well as the aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis-4 (FIB-4) were calculated. Their correlations with fibrosis stages and the diagnostic efficacy in predicting liver fibrosis were assessed and compared.

RESULTS

D (r = -0.667), β (r = -0.671), μ (r = -0.481), and ADC (r = -0.665) displayed significant correlations with fibrosis stages (p < 0.001). D, β and ADC (p < 0.01) were independently associated with fibrosis; and compared to inflammatory activity, fibrosis was the independent factor significantly correlated with D, β and ADC (p < 0.001). There were no significant differences between the area under curves of D, β, μ or their combinations and ADC for predicting different fibrosis stages (p > 0.05). The diagnostic performance of the combined index with four diffusion metrics was better than D, β, μ or ADC used alone (p < 0.05) as well as APRI or FIB-4 (p < 0.01) in fibrosis staging.

CONCLUSION

FROC-DWI was valuable in staging liver fibrosis in patients with CHB, but there were no significant differences between the FROC-DWI parameters and the classical ADC. However, the combined DWI-derived index including D, β, μ and ADC offered the best diagnostic efficacy and may serve as a reliable tool for fibrosis evaluation, superior to APRI and FIB-4.

Detection of liver and spleen stiffness in rats with portal hypertension by two-dimensional shear wave elastography

BACKGROUND

The measurement of liver stiffness (LS) and spleen stiffness (SS) based on ultrasound elastography can be used for non-invasive assessment of portal hypertension (PH). However, there are few studies on the corresponding mechanism of increased spleen stiffness. Our aim was to use two-dimensional shear wave elastrography (2D-SWE) to evaluate the relationship between LS and SS and the severity of PH in rats. And explore the mechanism of the increase of LS and SS in PH.

METHODS

Sixty male Sprague-Dawley rats were randomly divided into portal hypertension (PH group, n = 45) and normal control (NC group, n = 15). At 12 weeks, LS and SS was detected by 2D-SWE in vivo. Related hemodynamic parameters and portal vein pressure (PVP) was measured. Spleen and liver 2D-SWE detection was performed again after sacrifice. Pathological changes were observed.

RESULTS

The SS and LS were increased in PH group (P < 0.05). The SS decreased after sacrifice, and what's more the magnitude of SS decline significantly higher in PH group than in NC group (P < 0.05). The correlation between SS and PVP is stronger than LS (r = 0.624, P < 0.001). SS has positive correlation with indexes of hyperdynamic circulation, but LS was weakly. The correlation between SS and the pathological grade (r = 0.633, P < 0.001) was lower than that in LS (r = 0.905, P < 0.001). Multiple linear regression analysis revealed that SS, portal vein inner diameter (PVD) and splenic vein blood flow velocity (SVV) were significantly associated with PH.

CONCLUSIONS

Spleen and liver measurement by 2D-SWE may be helpful in evaluating PVP. The correlation between SS and PVP is stronger than LS in rats measured by 2D-SWE. Hemodynamic circulation are important in the elevation of SS with portal hypertension. Pathological changes also have a degree of influence, but have more significance for the elevation of LS. SS may be a more effective noninvasive predictor of PH than LS.

Quantitative Assessment of Portal Hypertension by Two-Dimensional Shear Wave Elastography in Rat Models of Nonalcoholic Fatty Liver Disease: Comparison With Four Composite Scores

Background

Measurement of hepatic venous pressure gradients is the gold standard for assessing portal hypertension (PH) but is invasive with potential complications. We aimed to assess the performance in liver and spleen stiffness measurement (LSM and SSM, respectively) by two-dimensional shear wave elastography (2D-SWE) and composite scores including liver stiffness-spleen diameter to platelet ratio score (LSPS), platelet (PLT) count/spleen diameter ratio (PSR), aspartate aminotransferase (AST)/alanine aminotransferase ratio (AAR), and AST-to-PLT ratio index (APRI) for diagnosing PH in nonalcoholic fatty liver disease (NAFLD) rat models.

Methods

Animal models with PH in NAFLD were established in 65 rats, which then underwent 2D-SWE measurements. Morphological and biological parameters were collected for calculation of four composite scores. Correlations of noninvasive methods with portal venous pressure were evaluated by Spearman correlation analysis. The area under the receiver operating characteristic curve (AUC) was used to assess the performance of noninvasive methods in predicting PH.

Results

LSM and SSM were significantly associated with portal venous pressure (r = 0.636 and 0.602, respectively; all P < 0.001). The AUCs of LSM and SSM in the diagnosis of PH were 0.906 (95% confidence interval [CI]:0.841–0.97) and 0.87 (95% CI:0.776–0.964), respectively, and were significantly higher than those in composite scores. The AUCs for LSPS, PSR, AAR, and APRI were 0.793, 0.52, 0.668, and 0.533, respectively, for diagnosing PH. The AUCs of the combined models of LSM and SSM, LSM and PLT, SSM and PLT, and LSM, SSM and PLT were 0.923, 0.913, 0.872, and 0.923, respectively. The four combined models showed no statistical differences compared to LSM and SSM in evaluating PH (all P > 0.05).

Conclusions

LSM and SSM by 2D-SWE can be used as promising noninvasive parameters for diagnosing PH in NAFLD and have higher accuracy than composite scores. The combined models, compared to LSM and SSM, did not significantly improve the performance in diagnosing PH.

Evaluation of liver fibrosis in chronic hepatitis B patients with 2D shear wave elastography with propagation map guidance: a single-centre study

Background

The aims of this study were to evaluate liver fibrosis with two-dimensional (2D) shear wave elastography (SWE) in patients with chronic hepatitis B (CHB), to compare 2D-SWE with histopathology and to determine the change in liver stiffness values after antiviral therapy.

Material and methods

A total of 253 patients with CHB were included in this prospective study. 2D-SWE with propagation map guidance to measure liver stiffness, fibrosis-4 index (FIB-4) and aspartate aminotransferase to platelet ratio index (APRI) scoring and additional liver biopsy were performed in patients with CHB. Liver stiffness was measured again at 24 and 48 weeks in all patients. The Spearman rank correlation test was used to analyse the correlation between variables, and receiver operating curve analysis was used to evaluate the diagnostic performance in terms of fibrosis.

Results

Liver stiffness measurements made with 2D-SWE demonstrated a significant positive correlation with the fibrosis stage and FIB-4 score (r_s = 0.774 and 0.337, respectively, p < 0.001 for both). The area under the curve value for kPa for the prediction of significant fibrosis was 0.956 (95% CI_s) (0.920–0.991), and the optimal cut-off value was 8.2 kPa (sensitivity: 92.7% and specificity: 78.9%); these values were 0.978 (95% CI_s, 0.945–1.000) and 10.1 kPa (sensitivity: 92.9% and specificity: 96.4%) for the prediction of severe fibrosis. After antiviral treatment, a decrease in liver stiffness values measured by 2D-SWE was detected (mean kPa values at 0 and 48 weeks; 9.24 and 7.36, respectively, p < 0.001).

Conclusion

In conclusion, the measurement of liver stiffness with 2D-SWE has high diagnostic performance in the determination of hepatic fibrosis and can be used to evaluate the response to treatment in patients receiving antiviral therapy.

Quality Control of Magnetic Resonance Elastography Using Percent Measurable Liver Volume Estimation

BACKGROUND

Although studies have described factors associated with failed magnetic resonance elastography (MRE), little is known about what factors influence usable elastography data.

PURPOSE

To identify factors that have a negative impact on percent measurable liver volume (pMLV), defined as the proportion of usable liver elastography data relative to the volume of imaged liver in patients undergoing MRE.

STUDY TYPE

Retrospective.

SUBJECTS

A total of 264 patients (n = 132 males, n = 132 females; mean age = 57 years) with suspected or known chronic liver disease underwent MRE paired with a liver protocol MRI.

FIELD STRENGTH/SEQUENCE

MRE was performed on a single 1.5 T scanner using a two-dimensional gradient-recalled echo phase-contrast sequence with a passive acoustic driver overlying the right hemiliver.

ASSESSMENT

Stiffness maps (usable data at 95% confidence) and liver contours on magnitude images of the MRE acquisition were manually traced and used to assess mean stiffness and pMLV. Hepatic fat fraction and R² * values were also calculated. The distance from the acoustic wave generator on the skin surface to the liver edge was measured. Two radiologists performed the MR analyses with 50 overlapping cases for inter-reader analysis.

STATISTICAL TESTS

Linear regression was performed to identify factors significantly associated with pMLV. Intraclass correlation was performed for inter-reader reliability.

RESULTS

pMLV was 31% ± 20% (range 0%-86%). Complete MRE failure (i.e. pMLV = 0%) occurred in 10 patients (4%). Multivariate linear regression identified higher hepatic fat fraction, R² *, BMI, and driver-to-liver surface distance; male sex; and lower mean liver stiffness was significantly independently associated with lower pMLV. Intraclass correlation for pMLV was 0.96, suggestive of excellent reliability.

DATA CONCLUSION

Higher fat fraction, R² *, BMI, driver-to-liver surface distance, male sex, and lower mean liver stiffness were associated with lower pMLV. Optimization of image acquisition parameters and driver placement may improve MRE quality, and pMLV likely serves as a diagnostic utility quality control metric.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 2.

Diagnostic Performance of 2-D Shear-Wave Elastography with Propagation Maps and Attenuation Imaging in Patients with Non-Alcoholic Fatty Liver Disease

We aimed to investigate the diagnostic performance of new 2-D shear-wave elastography (SWE) with propagation maps and attenuation imaging (ATI) for quantification of fibrosis and steatosis in non-alcoholic fatty liver disease (NAFLD). Consecutive patients with NAFLD and healthy volunteers underwent liver stiffness measurement and steatosis quantification by means of vibration-controlled transient elastography coupled with the controlled attenuation parameter as the reference and by 2-D shear-wave elastography (2-D-SWE) with propagation maps and ATI as the investigational methods. We included 232 participants (164 in the NAFLD group and 68 in the healthy control group): 51.7%/49.3% women/men; mean age, 54.2 ± 15.2 y; mean body mass index, 29.4 ± 6.5 kg/m². Significant correlations were found between 2-D-SWE and vibration-controlled transient elastography (r = 0.71, p < 0.0001) and between ATI and the controlled attenuation parameter (r = 0.72, p < 0.0001). NAFLD-specific 2-D-SWE liver stiffness measurement cutoffs were as follows-F ≥ 2: 7.9 kPa (area under the curve [AUC] = 0.91); F ≥ 3: 10 kPa (AUC = 0.92); and F = 4: 11.4 kPa (AUC = 0.95). For steatosis, the best cutoffs by ATI were as follows-S1 = 0.73 dB/cm/MHz (AUC = 0.86); S2 = 0.76 dB/cm/MHz (AUC = 0.86); and S3 = 0.80 dB/cm/MHz (AUC = 0.83). According to Baveno VI criteria, the optimal 2-D-SWE liver stiffness measurement for diagnosing liver cirrhosis is 15.5 kPa (AUC = 0.94), and for ruling out compensated advanced chronic liver disease it is 9.2 kPa (AUC = 0.92). To conclude, 2-D-SWE with propagation maps and ATI is reliable for quantification of liver fibrosis and steatosis in patients with NAFLD.

Intra-System Reliability Assessment of 2-Dimensional Shear Wave Elastography

The availability of 2-Dimensional Shear Wave Elastography (2D-SWE) technology on modern medical ultrasound systems is becoming increasingly common. The technology is now being used to investigate a range of soft tissues and related pathological conditions. This work investigated the reliability of a single commercial 2D-SWE system using a tissue-mimicking elastography phantom to understand the major causes of intra-system variability. Sources of shear wave velocity (SWV) measurement variability relates to imaging depth, target stiffness, sampling technique and the operator. Higher SWV measurement variability was evident with increasing depth and stiffness of the phantom targets. The influence of the operator was minimal, and variations in sampling technique had little impact on the SWV.

Advances in Magnetic Resonance Elastography of Liver

Magnetic resonance elastography (MRE) is the most accurate noninvasive technique in diagnosing fibrosis and cirrhosis in patients with chronic liver disease (CLD). The accuracy of hepatic MRE in distinguishing the severity of disease has been validated in studies of patients with various CLDs. Advanced hepatic MRE is a reliable, comfortable, and inexpensive alternative to liver biopsy for disease diagnosing, progression monitoring, and clinical decision making in patients with CLDs. This article summarizes current knowledge of the technical advances and innovations in hepatic MRE, and the clinical applications in various hepatic diseases.

Added value of 2D shear wave imaging of the gallbladder bed of the liver for acute cholecystitis

Purpose

The purpose of this study was to evaluate whether shear wave elastography (SWE) and the shear wave dispersion slope (SWD) obtained from 2-dimensional shear wave imaging (2D-SWI) of the gallbladder (GB) bed of the liver could be helpful in the diagnosis of acute cholecystitis.

Methods

We included 44 patients referred for abdominal ultrasonography (US) under the impression of acute cholecystitis from April 2018 to March 2019. Patients with chronic liver disease were excluded from this study. In addition to routine upper abdominal US, we performed 2D-SWI including liver stiffness measurements by SWE and SWD, which reflects tissue viscosity. 2D-SWI was performed at the GB bed of the liver through the right intercostal approach at least 3 times with different frames. We assessed typical US findings and the added value of 2D-SWI in diagnosing acute cholecystitis. Histopathologic results of surgical specimens were used as the standard of reference. If a surgical specimen was unavailable, a bile fluid test or clinical follow-up for more than 3 months served as the reference standard.

Results

The optimal cutoff values for SWE and SWD were 8 kPa and 10.9 (m/sec)/kHz, respectively. In the univariate analysis, SWE, GB distension, and sludge were predictive factors of acute cholecystitis. In the multivariate analysis, categorized SWE was the only significant predictor (P<0.01). By using 2D-SWI, the diagnostic performance of two readers did not significantly increase, although the inter-reader agreement improved (k=0.654-0.778).

Conclusion

2D-SWI of the GB bed of the liver could be helpful for diagnosing acute cholecystitis.