Noninvasive in vivo liver fibrosis evaluation using supersonic shear imaging: a clinical study on 113 hepatitis C virus patients

Supersonic shear imaging (SSI) has recently been demonstrated to be a repeatable and reproducible transient bidimensional elastography technique. We report a prospective clinical evaluation of the performances of SSI for liver fibrosis evaluation in 113 patients with hepatitis C virus (HCV) and a comparison with FibroScan (FS). Liver elasticity values using SSI and FS ranged from 4.50 kPa to 33.96 kPa and from 2.60 kPa to 46.50 kPa, respectively. Analysis of variance (ANOVA) shows a good agreement between fibrosis staging and elasticity assessment using SSI and FS (p < 10⁻⁵). The areas under receiver operating characteristic (ROC) curves for elasticity values assessed from SSI were 0.948, 0.962 and 0.968 for patients with predicted fibrosis levels F ≥ 2, F ≥ 3 and F = 4, respectively. These values are compared with FS area under the receiver operating characteristic curve (AUROC) of 0.846, 0.857 and 0.940, respectively. This comparison between ROC curves is particularly significant for mild and intermediate fibrosis levels. SSI appears to be a fast, simple and reliable method for noninvasive liver fibrosis evaluation.     

In vivo Quantification of Liver Stiffness in a Rat Model of Hepatic Fibrosis with Acoustic Radiation Force

Liver fibrosis is currently staged using needle biopsy, a highly invasive procedure with a number of disadvantages. Measurement of liver stiffness changes that accompany progression of the disease may provide a quantitative and noninvasive method to assess the health of the liver. The purpose of this study is to investigate the correlation between liver stiffness measured by radiation force induced shear waves and disease related changes in the liver. An additional aim is to present initial findings on the effects of liver viscosity on radiation force induced shear wave morphology. Liver fibrosis was induced in 10 rats using carbon tetrachloride (CCl₄), while five rats acted as controls. Liver stiffness was measured in vivo in all rats after a treatment period of 8 weeks using a modified Siemens SONOLINE Antares scanner (Siemens Medical Solutions USA, Ultrasound Division, Issaquah, WA, USA). The spatial coherence of radiation force induced shear waves propagating in the viscoelastic rat liver decreased significantly with propagation distance, compared with shear waves in an elastic phantom and a finite element model of a purely elastic medium. Animals were sacrificed after imaging and liver samples were taken for histopathologic analysis and collagen quantification using picrosirius red staining and hydroxyproline assay. At the end of the treatment period, five rats had healthy livers (stage F0), while six had severe fibrosis (F3) and the rest had light to moderate fibrosis (F1 and F2). The measured liver stiffness for the F0 group was 1.5 ± 0.1 kPa (mean ± 95% confidence interval) and for F3 livers was 1.8 ± 0.2kPa. In this study, liver stiffness was found to be linearly correlated with the amount of collagen in the liver measured by picrosirius red staining (r² = 0.43, p = 0.008). In addition, stiffness spatial heterogeneity was also linearly correlated with liver collagen content (r² = 0.58, p = 0.001) by picrosirius red staining. These results are consistent with those obtained by Salameh et al. (2007) and Yin et al. (2007b) using animal models of liver fibrosis and MR elastography. This suggests that stiffness measurement using acoustic radiation force can provide a quantitative assessment of the extent of fibrosis in the liver and can be potentially used for the diagnosis, management and study of liver fibrosis. (E-mail: michael.h.wang@duke.edu)     

Shear Wave Elastography for Assessment of Steatohepatitis and Hepatic Fibrosis in Rat Models of Non-Alcoholic Fatty Liver Disease

The purpose of this study was to evaluate shear wave elastography (SWE) as a method for determining the severity of non-alcoholic fatty liver disease (NAFLD) and the stage of hepatic fibrosis, as well as the major determinants of liver elasticity among the various histologic and biomolecular changes associated with NAFLD. Rat NAFLD models with various degrees of NAFLD severity were created and imaged using SWE. The explanted livers were subjected to histopathologic evaluation and RNA expression analysis. Among the histologic and biomolecular findings, the fibrosis stage and the collagen RNA level were significant independent factors associated with liver elasticity (p < 0.001). Liver elasticity was effective in detecting non-alcoholic steatohepatitis (NASH) and in determining fibrosis stage, and the corresponding areas under the receiver operating characteristic curves were 0.963 and 0.927–0.997, respectively. In conclusion, SWE is a potential non-invasive method for the detection of NASH and staging of hepatic fibrosis in patients with NAFLD.     

基于压痕松弛实验的黏弹性参数评价大鼠肝纤维化的实验研究

目的探讨基于压痕松弛实验的黏弹性参数评价肝纤维化的可行性,以期为弹性成像诊断肝纤维化提供有价值的参数和方法。 方法选取雄性SD大鼠50只,平均体质量（180±20）g,将其分为2组,肝纤维化组（40只）和对照组（10只）。最终纳入43只,其中肝纤维化组36只,对照组7只。实验组大鼠采用四氯化碳-橄榄油溶液建立肝纤维化模型,对照组大鼠采用单纯橄榄油溶液灌胃。分离大鼠肝脏后进行压痕松弛实验,测算肝脏黏弹性参数。对离体肝脏病理标本进行肝组织纤维化分期（S1~S4期）。对不同肝纤维化分期的各组大鼠黏弹性参数进行比较,并进行黏弹性参数与大鼠肝纤维化程度的相关性分析。 结果对照组与肝纤维化S1~S4期各组的黏弹性参数应力下降开始时的变化程度（g₁）、应力降低到平衡时的变化程度（g₂）、黏弹性材料的总松弛程度（g₁＋g₂）、应力下降开始时间（τ₁）、应力降低到平衡时的时间（τ₂）进行比较,τ₁、τ₂、g₁组间差异有统计学意义（F=23.598、2.836、2.506,P均<0.05）,进一步两两比较,黏弹性参数τ₁在正常肝脏组与S1、S2、S3、S4期肝纤维化组之间的差异均有统计学意义（t=2.367、1.689、2.887、3.195,P均<0.05）;黏弹性参数τ₂在S1期和S3期肝纤维化组之间差异有统计学意义（t=2.048,P<0.05）;黏弹性参数g₁在S2期和S3期肝纤维化组之间差异有统计学意义（t=3.211,P<0.05）。Spearman相关性分析显示,黏弹性参数g₁、g₁＋g₂与肝纤维化程度呈正相关（r=0.513、0.439,P均<0.001）,τ₁与肝纤维化程度呈负相关（r=-0.509,P<0.001）。 结论黏弹性参数与肝纤维化分期具有相关性,将黏弹性参数应用于大鼠肝脏纤维化分期的评估具有可行性,这也为黏弹性参数运用于剪切波弹性成像评价肝纤维化提供了可靠的实验论据。     

Shear Wave Elastography for Evaluation of Liver Fibrosis

The prognosis and management of chronic viral hepatitis mainly depend on the extent of liver fibrosis, particularly in chronic hepatitis C. Liver histologic analysis is still considered the reference standard in the assessment of liver fibrosis despite the interobserver and interobserver variability in staging and some morbidity and mortality risks. Thus, noninvasive methods for assessing liver fibrosis are of great clinical interest. In the last decade, ultrasound‐based techniques to estimate the stage of liver fibrosis have become commercially available. They all have the capability to noninvasively evaluate differences in the elastic properties of soft tissues by measuring tissue behavior when a mechanical stress is applied. Shear wave elastography relies on the generation of shear waves determined by the displacement of tissues induced by the force of a focused ultrasound beam or by an external push. This article reviews the results that have been obtained with shear wave elastography for assessment of liver fibrosis.     

超声定量评估肝纤维化程度研究进展

肝纤维化程度的判断对于监测肝脏疾病的进展和监控药物疗效具有重要意义。作为肝纤维化分期金标准的肝活检因为有创操作,临床上不能广泛开展。而超声作为一种无创性的影像学技术,越来越多地被用于评价肝纤维化程度。本文对瞬时弹性成像技术、实时组织弹性成像技术、声脉冲辐射力弹性成像技术、实时剪切波弹性成像、组织结构声学定量技术,用于无创定量评估肝纤维化程度的研究进展进行综述。     

Factors Which Influence the Accuracy of Acoustic Radiation Force Impulse (ARFI) Elastography for the Diagnosis of Liver Fibrosis in Patients with Chronic Hepatitis C

Our study tried to identify the factors associated with discordance between liver stiffness values assessed by acoustic radiation force impulse (ARFI) elastography and histologic fibrosis in 106 chronic hepatitis C patients. Liver biopsy (LB) and ARFI measurements were performed in the same session. A discordance of at least two stages of fibrosis in the Metavir scoring system between ARFI results and LB was defined as significant. The performance of ARFI elastography was assessed using the following cut-offs: F1-1.19 m/s, F2-1.34 m/s, F3-1.55 m/s and F4-1.80 m/s. Discordance of at least two stages of fibrosis between ARFI results and histologic assessment were observed in 31.7% of the patients. In an univariate analysis, female sex (p = 0.004), interquartile range interval (IQR) ≥30% (p = 0.04), high alanine aminotransferases (p = 0.008) and high aspartate aminotransferases levels (p = 0.003) were associated with discordances. In a multivariate analysis, the female sex (p = 0.006) and IQR ≥30% (p = 0.004) were associated with discordances. Therefore, IQR parameter should be used for ARFI measurements.     

实时双幅联合弹性成像在慢性肝病肝纤维化与炎症分层诊断中的价值

目的评估联合弹性成像技术的纤维化相关F指数和炎症活动度相关A指数在分层诊断肝纤维化和炎症程度中的应用价值。 方法收集2019年9月至2021年4月在复旦大学附属华山医院就诊并接受经皮肝穿刺活检或肝部分切除术并获得病理结果的202例慢性肝病患者,其中49例因肝占位性病变而行肝部分切除术,153例因弥漫性肝病行肝穿刺活检。所有患者在术前进行联合弹性成像检查,获得肝纤维化相关F指数和炎症活动度相关A指数;以病理诊断肝纤维化分期（S0~S4期）和炎症活动分级（G0~G4级）为金标准,使用Kruskal-Wallis秩和检验和Bonferroni校正比较不同纤维化分期的F指数以及不同炎症活动分级的A指数的差异,绘制受试者操作特征曲线,使用DeLong检验比较F指数与剪切波速度、实时组织弹性成像的肝纤维化指数（LFI）、天冬氨酸转氨酶与血小板的比率指数（APRI）在肝纤维化无创诊断中的效能。 结果肝纤维化分期S0（40例）、S1（42例）、S2（41例）、S3（34例）和S4期（45例）患者的F指数中位数分别为0.89、1.17、1.45、1.75和2.30,相邻纤维化分期之间的F指数中位数比较,差异均具有统计学意义（P＜0.05）。F指数在诊断纤维化分期≥S1、≥S2、≥S3和≥S4的临界值分别为1.14、1.45、1.50和1.63,受试者操作特征曲线下面积（AUC）分别为0.91、0.89、0.90和0.91,均高于LFI（AUC=0.66、0.68、0.69、0.69）与APRI（AUC=0.71、0.68、0.72、0.77）,差异均具有统计学意义（P均＜0.05）;F指数诊断纤维化分期≥S1、≥S2期的AUC高于剪切波速度（AUC=0.84、0.85）,差异具有统计学意义（P均＜0.05）。炎症活动度分级G0（26例）、G1（86例）、G2（68例）和G3-4（22例）级患者的A指数中位数分别为0.83、0.99、1.29和1.69。相邻等级间的A指数中位数比较,差异均具有统计学意义（P均＜0.05）。A指数区分≥G1、≥G2和≥G3-4的临界值分别为0.87、1.15和1.41,AUC分别为0.86、0.87和0.92。 结论联合弹性成像技术获得的A指数能很好地评估肝炎症活动度;F指数则校正了肝细胞炎症活动对肝组织硬度测量的影响,能更准确地诊断肝纤维化分期。     

Comparison of 2-D Shear Wave Elastography and Transient Elastography for Assessing Liver Fibrosis in Chronic Hepatitis B

This study compared 2-D shear wave elastography (SWE) and transient elastography (TE) for liver fibrosis staging in patients with chronic hepatitis B (CHB) infection using liver biopsy as the reference standard. Patients with CHB infection who underwent liver biopsy were consecutively included. After exclusions, 257 patients were analyzed. Two-dimensional SWE resulted in a significantly higher rate of reliable measurements (98.1%, 252/257) than TE (93.0%, 239/257) (p = 0.011). Liver stiffness measurements of the two examinations exhibited a strong correlation (r = 0.835, p < 0.001). In patients given a confirmed histologic diagnosis, Spearman's rank coefficients were 0.520 in stage F0 (p < 0.001), 0.684 in stage F1 (p < 0.001), 0.777 in stage F2 (p < 0.001), 0.672 in stage F3 (p < 0.001) and 0.755 in stage F4 (p < 0.001). There were no significant differences between the areas under the receiver operating characteristic (ROC) curves of 2-D SWE and TE for liver fibrosis staging (all p values > 0.05). Two-dimensional SWE had diagnostic accuracy comparable to that of TE for liver fibrosis staging. The measurements that the two techniques provide are not interchangeable.     

Hepatic Elastometry and Glissonian Line in the Assessment of Liver Fibrosis

The aim of this study was to identify a method for staging hepatic fibrosis using a non-invasive, rapid and inexpensive technique based on ultrasound morphologic hepatic features. A total of 215 patients with different liver diseases underwent B-mode (2-D brightness mode) ultrasonography, vibration-controlled transient elastography, 2-D shear wave elastography and measurement of the controlled attenuation parameter with transient elastography. B-Mode images of the anterior margin of the left lobe were obtained and processed with automatic Genoa Line Quantification (GLQ) software based on a neural network for staging liver fibrosis. The accuracy of GLQ was 90.6% during model training and 78.9% in 38 different patients with concordant elastometric measures. Receiver operating characteristic curve analysis of GLQ performance using vibration-controlled transient elastography as a reference yielded areas under the curves of 0.851 for F ≥ F1, 0.793 for F ≥ F2, 0.784 for F ≥ F3 and 0.789 for F ≥ F4. GLQ has the potential to be a rapid, easy-to-perform and tolerable method in the staging of liver fibrosis.     

Transient elastography: a new noninvasive method for assessment of hepatic fibrosis

Chronic hepatitis is accompanied by progressive deposit of hepatic fibrosis, which may lead to cirrhosis. Evaluation of liver fibrosis is, thus, of great clinical interest and, up to now, has been assessed with liver biopsy. This work aims to evaluate a new noninvasive device to quantify liver fibrosis: the shear elasticity probe or fibroscan®. This device is based on one-dimensional (1-D) transient elastography, a technique that uses both ultrasound (US) (5 MHz) and low-frequency (50 Hz) elastic waves, whose propagation velocity is directly related to elasticity. The intra- and interoperator reproducibility of the technique, as well as its ability to quantify liver fibrosis, were evaluated in 106 patients with chronic hepatitis C. Liver elasticity measurements were reproducible (standardized coefficient of variation: 3%), operator-independent and well correlated (partial correlation COEFFICIENT = 0.71, p < < 0.0001) to fibrosis grade (METAVIR). The areas under the receiver operating characteristic (ROC) curves were 0.88 and 0.99 for the diagnosis of patients with significant fibrosis (≥ F2) and with cirrhosis ( = F4), respectively. The Fibroscan® is a noninvasive, painless, rapid and objective method to quantify liver fibrosis. (E-mail: laurent.sandrin@echosens.com)     

The Role of Viscosity Estimation for Oil-in-gelatin Phantom in Shear Wave Based Ultrasound Elastography

Shear wave based ultrasound elastography utilizes mechanical excitation or acoustic radiation force to induce shear waves in deep tissue. The tissue response is monitored to obtain elasticity information about the tissue. During the past two decades, tissue elasticity has been extensively studied and has been used in clinical disease diagnosis. However, biological soft tissues are viscoelastic in nature. Therefore, they should be simultaneously characterized in terms of elasticity and viscosity. In this study, two shear wave-based elasticity imaging methods, shear wave dispersion ultrasound vibrometry (SDUV) and acoustic radiation force impulsive (ARFI) imaging, were compared. The discrepancy between the measurements obtained by the two methods was analyzed, and the role of viscosity was investigated. To this end, four types of gelatin phantoms containing 0%, 20%, 30% and 40% castor oil were fabricated to mimic different viscosities of soft tissue. For the SDUV method, the shear elasticity μ₁ was 3.90 ± 0.27 kPa, 4.49 ± 0.16 kPa, 2.41 ± 0.33 kPa and 1.31 ± 0.09 kPa; and the shear viscosity μ₂ was 1.82 ± 0.31 Pa•s, 2.41 ± 0.35 Pa•s, 2.65 ± 0.13 Pa•s and 2.89 ± 0.14 Pa•s for 0%, 20%, 30% and 40% oil, respectively in both cases. For the ARFI measurements, the shear elasticity μ was 7.30 ± 0.20 kPa, 8.20 ± 0.31 kPa, 7.42 ± 0.21 kPa and 5.90 ± 0.36 kPa for 0%, 20%, 30% and 40% oil, respectively. The SDUV results demonstrated that the elasticity first increased from 0% to 20% oil and then decreased for the 30% and 40% oil. The viscosity decreased consistently as the concentration of castor oil increased from 0% to 40%. The elasticity measured by ARFI showed the same trend as that of the SDUV but exceeded the results measured by SDUV. To clearly validate the impact of viscosity on the elasticity estimation, an independent measurement of the elasticity and viscosity by dynamic mechanical analysis (DMA) was conducted on these four types of gelatin phantoms and then compared with SDUV and ARFI results. The shear elasticities obtained by DMA (3.44 ± 0.31 kPa, 4.29 ± 0.13 kPa, 2.05 ± 0.29 kPa and 1.06 ± 0.18 kPa for 0%, 20%, 30% and 40% oil, respectively) were lower than those by SDUV, whereas the shear viscosities obtained by DMA (2.52 ± 0.32 Pa·s, 3.18 ± 0.12 Pa·s, 3.98 ± 0.19 Pa·s and 4.90 ± 0.20 Pa·s for 0%, 20%, 30% and 40% oil, respectively) were greater than those obtained by SDUV. However, the DMA results showed that the trend in the elasticity and viscosity data was the same as that obtained from the SDUV and ARFI. The SDUV results demonstrated that adding castor oil changed the viscoelastic properties of the phantoms and resulted in increased dispersion of the shear waves. Viscosity can provide important and independent information about the inner state of the phantoms, in addition to the elasticity. Because the ARFI method ignores the dispersion of the shear waves, namely viscosity, it may bias the estimation of the true elasticity. This study sheds further light on the significance of the viscosity measurements in shear wave based elasticity imaging methods.     

实时超声弹性成像半定量分析大鼠肝纤维化

目的探讨超声弹性成像评估大鼠肝纤维化的应用价值。方法以52只Wistar大鼠建立肝纤维化模型,对动物模型进行超声弹性成像,通过弹性图像评分来评估肝纤维化程度,并与病理结果对照。结果 52只大鼠模型中,Scheuer病理分期S1期16只,S2期14只,S3期12只,S4期10只。实时超声弹性成像判断S1、S2、S3及S4期肝纤维化的敏感度分别为87.50%(14/16)、78.57%(11/14)、83.33%(10/12)和90.00%(9/10),特异度分别为83.33%(5/6)、71.43%(10/14)、77.78%(7/9)和85.71%(6/7)。结论实时超声弹性成像评分方法可作为半定量分析大鼠肝纤维化的有效手段。     

Comparison of interobserver agreement of magnetic resonance elastography with histopathological staging of liver fibrosis

Purpose

MR elastography (MRE) can serve as an accurate surrogate marker of liver fibrosis. For any diagnostic test that is to replace the current reference standard, interobserver agreement should be at least as good and preferably better. The objective of this study was to perform a head-to-head comparison of the interobserver agreements of MRE and liver fibrosis staging on biopsy in a single cohort of hepatitis patients.

Methods

One hundred and three patients with viral hepatitis B or C who had a liver biopsy underwent MRE. Two readers independently selected a region-of-interest (ROI) in the liver to derive elasticity values. Two pathologists first independently staged fibrosis on biopsies using the METAVIR classification and subsequently held a consensus meeting. Interobserver agreements of elasticity values and fibrosis stages were assessed with intraclass correlation coefficients (ICC).

Results

MRE and biopsy data were available for 85/103 patients. ICC of pathologists staging fibrosis was almost perfect at 0.91 (95% CI 0.86–0.94). ICC for MRE readers was significantly (P < 0.0001) higher at 0.99 (95% CI 0.98–1.00).

Conclusions

Interobserver agreement for liver fibrosis staging was almost perfect for both histopathology and MRE, with a significant higher agreement for MRE. Its high interobserver agreement and reliable accuracy support the use of MRE as a non-invasive screening tool for liver fibrosis.     

Comparison of 2-D Shear Wave Elastography and Point Shear Wave Elastography for Assessing Liver Fibrosis

Progressive liver fibrosis may result in cirrhosis, portal hypertension and increased risk of hepatocellular carcinoma. We performed a meta-analysis to compare liver fibrosis staging in chronic liver disease patients using 2-D shear wave elastography (2-D SWE) and point shear wave elastography (pSWE). The PubMed, Web of Science and Cochrane Library databases were searched until May 31, 2020 for studies evaluating the diagnostic performance of 2-D SWE and pSWE in assessing liver fibrosis. Pooled sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratios and area under receiver operating characteristic curve were estimated using the bivariate random effects model. As a result, 71 studies with 11,345 patients were included in the analysis. The pooled sensitivities of 2-D SWE and pSWE significantly differed for the detection of significant fibrosis (F ≥ 2; 0.84 vs. 0.76, p < 0.001) and advanced fibrosis (F ≥ 3; 0.90 vs. 0.83, p = 0.003), but not for detection of cirrhosis (F = 4; 0.89 vs. 0.85, p = 0.090). The pooled specificities of 2-D SWE and pSWE did not significantly differ for detection of F ≥ 2 (0.81 vs. 0.79, p = 0.753), F ≥ 3 (0.87 vs. 0.83, p = 0.163) or F = 4 (0.87 vs. 0.84, p = 0.294). Both 2-D SWE and pSWE have high sensitivity and specificity for detecting each stage of liver fibrosis. Two-dimensional SWE has higher sensitivity than pSWE for detection of significant fibrosis and advanced fibrosis.     

Non-invasive Assessment of Liver Fibrosis in a Rat Model: Shear Wave Elasticity Imaging Versus Real-Time Elastography

The purpose of this study was to investigate the diagnostic value of shear wave elasticity imaging (SWEI) and real-time elastography (RTE) in liver fibrosis induced by dimethylnitrosamine (DMN) and to compare the accuracy of these methods. Seventy male Wistar rats given a single intra-peritoneal injection of DMN and 10 control rats given a saline injection underwent SWEI and RTE to determine their shear wave velocity (V_s) and liver fibrosis (LF) index, respectively. Correlations between V_s or the LF index and histologic stage of liver fibrosis (S0–S4) were analyzed, and the diagnostic values of the techniques were assessed using a receiver operating characteristic curve. A positive correlation was found between V_s and stage of liver fibrosis (r = 0.947, p < 0.001) and between LF index and stage (S) of liver fibrosis (r = 0.662, p < 0.001). For V_s, the areas under the receiver operating characteristic curve for the diagnosis of fibrosis, S ≥ S1, S ≥ S2, S ≥ S3 and S = S4, were 0.983, 0.995, 0.999 and 0.964, respectively; for the LF index, the values were 0.871, 0.887, 0.761 and 0.839, respectively (all p < 0.001). V_s and the LF index values in rats with severe inflammatory activity were significantly higher than those in controls (p < 0.001). In conclusion, positive correlations exist between V_s or the LF index and the severity of liver fibrosis in rats. V_s is more accurate than the LF index in predicting liver fibrosis in rats. However, severe inflammatory activity may reduce the accuracy of both techniques.     

Assessment by transient elastography of the viscoelastic properties of blood during clotting

Blood clotting is a natural process that can be both beneficial and life-threatening for the human body. It allows the maintenance of hemostasis after vascular injury, but it can also cause deep vein thrombosis and heart stroke. This study aimed better to understand the clotting process from a biomechanical point of view by using an acoustic method. The long-term objective is the staging of the age of clots in deep veins for therapy planning. The transient elastography method using a shear elasticity probe served to evaluate the shear wave velocity (V(S)) and shear wave attenuation (alpha(S)) of porcine whole blood during in vitro clot formation. By solving an inverse problem, it was then possible to provide images of the elasticity (mu(B)) and of the viscosity (eta(B)) from clotting blood. The time-varying elasticity and viscosity were very similar to what has been observed for the sol-gel transition of polymers. The mechanical properties of blood clot, which were modified by varying the hematocrit and by adding heparin or fibrinogen, were clearly assessed by the transient elastography technique. It is concluded that the shear elasticity probe is an appropriate tool to quantify and follow the sol-gel transition of blood during clotting.     

Value of Acoustic Radiation Force Impulse Imaging Elastography for Non-invasive Evaluation of Patients with Nonalcoholic Fatty Liver Disease

The goals of the work described here were to evaluate the clinical utility of acoustic radiation force impulse (ARFI) elastography in differentiating non-alcoholic fatty liver disease (NAFLD) histologic subtypes and to determine if ARFI elastography measurements correlate with the severity of liver fibrosis. We compared ARFI elastography measurements with clinical, biologic and histologic features (simple steatosis or steatohepatitis) in 64 patients with histologically proven NAFLD. ARFI elastography is suitable for distinguishing patients with non-alcoholic steatohepatitis from those with simple steatosis, with an area under the receiver operating characteristic curve (AUROC) of 0.867 (95% confidence interval = 0.782–0.953). There was a highly significant correlation (r = 0.843) between ARFI elastography measurements and fibrosis (p < 0.001). In patients with non-alcoholic steatohepatitis, the diagnostic performance of ARFI elastography in predicting significant fibrosis (F ≥ 2) had an AUROC of 0.944. ARFI elastography better predicted F = 4 fibrosis (AUROC = 0.984). In conclusion, ARFI elastography is a promising method for differentiating patients with non-alcoholic steatohepatitis from patients with simple steatosis and can also predict significant fibrosis in these patients.     

Validation of Shear Wave Elastography Cutoff Values on the Supersonic Aixplorer for Practical Clinical Use in Liver Fibrosis Staging

The purpose of this study was to determine the validity of previously established ultrasound shear wave elastography (SWE) cut-off values (≥F2 fibrosis) on an independent cohort of patients with chronic liver disease. In this cross-sectional study, approved by the institutional review board and compliant with the Health Insurance Portability and Accountability Act, 338 patients undergoing liver biopsy underwent SWE using an Aixplorer ultrasound machine (SuperSonic Imagine, Aix-en-Provence, France). Median SWE values were calculated from sets of 10 elastograms. A single blinded pathologist evaluated METAVIR fibrosis staging as the gold standard. The study analyzed 277 patients with a mean age of 48 y. On pathologic examination, 212 patients (76.5%) had F0–F1 fibrosis, whereas 65 (23.5%) had ≥F2 fibrosis. Spearman's correlation of fibrosis with SWE was 0.456 (p < 0.001). A cut-off value of 7.29 kPa yielded sensitivity of 95.4% and specificity of 50.5% for the diagnosis of METAVIR stage ≥F2 liver fibrosis in patients with liver disease using the SuperSonic Imagine Aixplorer SWE system.     

Comparative Study Between the Diagnostic Performance of Point and 2-D Shear-Wave Elastography for the Non-invasive Assessment of Liver Fibrosis in Patients With Chronic Hepatitis C Using Transient Elastography as Reference

The study compared the diagnostic performance of two shear-wave elastography techniques, elastography point quantification (ElastPQ) and 2-D shear-wave elastography by General Electric (2-D-SWE.GE), for the non-invasive assessment of liver fibrosis in a cohort of patients with chronic hepatitis C virus (HCV) infection, using transient elastography (TE) as the reference method. There was no significant difference between the feasibility rates of TE, ElastPQ and 2-D-SWE.GE (p = 0.507). A good correlation was found between the liver stiffness (LS) values obtained using the two elastographic methods (r = 0.78). The mean LS values obtained using the ElastPQ technique were significantly higher than those obtained using 2-D-SWE.GE (12.1 ± 7.3 kPa vs. 10.4 ± 4.0 kPa, p < 0.0001). Pairwise comparisons of receiver operator characteristics curves between 2-D-SWE.GE and ElastPQ have shown that there are no significant differences in their performance for staging F ≥ 2 fibrosis (p = 0.89), F ≥ 3 fibrosis (p = 0.76) and F = 4 fibrosis (p = 0.86) in patients with chronic HCV infection.