Determination of normal hepatic elasticity by using real-time shear-wave elastography

What we need to know when performing and interpreting US elastography

According to the increasing need for accurate staging of hepatic fibrosis, the ultrasound (US) elastography techniques have evolved significantly over the past two decades. Currently, US elastography is increasingly used in clinical practice. Previously published studies have demonstrated the excellent diagnostic performance of US elastography for the detection and staging of liver fibrosis. Although US elastography may seem easy to perform and interpret, there are many technical and clinical factors which can affect the results of US elastography. Therefore, clinicians who are involved with US elastography should be aware of these factors. The purpose of this article is to present a brief overview of US techniques with the relevant technology, the clinical indications, diagnostic performance, and technical and biological factors which should be considered in order to avoid misinterpretation of US elastography results.

Ultrasound shear wave elastography and liver fibrosis: A Prospective Multicenter Study

AIM

To assess the accuracy of shear wave elastography (SWE) alone and in combination with aminotransferase platelet ratio index (APRI) score in the staging of liver fibrosis.

METHODS

A multicenter prospective study was conducted to assess the accuracy of SWE (medians) and APRI to predict biopsy results. The analysis focused on distinguishing the different stages of liver disease, namely, F0 from F1-4, F0-1 from F2-4, F0-2 from F3-4 and F0-3 from F4; F0-F1 from F2-F4 being of primary interest. The area under the receiver operating characteristic (AUROC) curve was computed using logistic regression model. The role of age, gender and steatosis was also assessed.

RESULTS

SWE alone accurately distinguished F0-1 from F2-4 with a high probability. The AUROC using SWE alone was 0.91 compared to 0.78 for using the APRI score alone. The APRI score, when used in conjunction with SWE, did not make a significant contribution to the AUROC. SWE and steatosis were the only significant predictors that differentiated F0-1 from F2-4 with an AUROC of 0.944.

CONCLUSION

Our study validates the use of SWE in the diagnosis and staging of liver fibrosis. Furthermore, the probability of a correct diagnosis is significantly enhanced with the addition of steatosis as a prognostic factor.

Shear Wave Elastography of Focal Liver Lesion: Intraobserver Reproducibility and Elasticity Characterization

PURPOSE

The aim of the study was to evaluate the intraobserver reproducibility and to determine the elasticity characteristics of focal liver lesions (FLLs) by shear wave elastography (SWE).

METHODS

One hundred thirty-six FLLs in 118 patients were examined with SWE for quantitative and qualitative assessment of stiffness. Three SWE images were obtained for each lesion and liver parenchyma by 1 radiologist. Intraobserver reproducibility was assessed by intraclass correlation coefficients (ICCs). Patient and lesion factors that can affect the reproducibility were evaluated. For characterization of the lesion elasticity, the difference in stiffness between the groups of lesions was evaluated.

RESULTS

The mean (SD) diameter and depth of the lesions were 3.98 (2.07) and 4.4 (1.59) cm, respectively. The ICC of intraobserver reproducibility was 0.763. Deep-seated lesions (≥6 cm; ICC, 0.621) showed significantly lower intraobserver reproducibility compared with superficial lesions (ICC, 0.793; P = 0.047). Stiffness values of malignant lesions (n = 85, 60.41 [47.81] kPa) were significantly higher than those of benign lesions (n = 51, 22.05 [17.24] kPa, P < 0.0001). Mean (SD) stiffness of hepatocellular carcinoma (45.72 [35.65] kPa) was significantly lower than that of metastasis (67.43 [43.39] kPa) and was significantly higher than benign FLLs (22.05 [17.24] kPa). However, mean (SD) lesion-parenchyma ratio of hepatocellular carcinoma (3.76 [4]) was not significantly different from that of benign FLLs (3.7 [3.77]).

CONCLUSIONS

Overall, intraobserver reproducibility of SWE in evaluation of FLLs was excellent, but it can be affected by lesion depth. In addition, SWE is helpful in elasticity characterization of FLLs.

Primary biliary cirrhosis degree assessment by acoustic radiation force impulse imaging and hepatic fibrosis indicators

AIM: To evaluate the assessment of primary biliary cirrhosis degree by acoustic radiation force impulse imaging (ARFI) and hepatic fibrosis indicators.

METHODS: One hundred and twenty patients who developed liver cirrhosis secondary to primary biliary cirrhosis were selected as the observation group, with the degree of patient liver cirrhosis graded by Child-Pugh (CP) score. Sixty healthy individuals were selected as the control group. The four indicators of hepatic fibrosis were detected in all research objects, including hyaluronic acid (HA), laminin (LN), type III collagen (PC III), and type IV collagen (IV-C). The liver parenchyma hardness value (LS) was then measured by ARFI technique. LS and the four indicators of liver fibrosis (HA, LN, PC III, and IV-C) were observed in different grade CP scores. The diagnostic value of LS and the four indicators of liver fibrosis in determining liver cirrhosis degree with PBC, whether used alone or in combination, were analyzed by receiver operating characteristic (ROC) curve.

RESULTS: LS and the four indicators of liver fibrosis within the three classes (A, B, and C) of CP scores in the observation group were higher than in the control group, with C class > B class > A class; the differences were statistically significant (P < 0.01). Although AUC values of LS within the three classes of CP scores were higher than in the four indicators of liver fibrosis, sensitivity and specificity were unstable. The ROC curves of LS combined with the four indicators of liver fibrosis revealed that: AUC and sensitivity in all indicators combined in the A class of CP score were higher than in LS alone, albeit with slightly decreased specificity; AUC and specificity in all indicators combined in the B class of CP score were higher than in LS alone, with unchanged sensitivity; AUC values (0.967), sensitivity (97.4%), and specificity (90%) of all indicators combined in the C class of CP score were higher than in LS alone (0.936, 92.1%, 83.3%).

CONCLUSION: The diagnostic value of PBC cirrhosis degree in liver cirrhosis degree assessment by ARFI combined with the four indicators of serum liver fibrosis is of satisfactory effectiveness and has important clinical application value.

Diagnostic Accuracy of 2D-Shear Wave Elastography for Liver Fibrosis Severity: A Meta-Analysis

Purpose

To evaluate the accuracy of shear wave elastography (SWE) in the quantitative diagnosis of liver fibrosis severity.

Methods

The published literatures were systematically retrieved from PubMed, Embase, Web of science and Scopus up to May 13^th, 2016. Included studies reported the pooled sensitivity, specificity, positive and negative predictive values, as well as the diagnostic odds ratio of SWE in populations with liver fibrosis. A bivariate mixed-effects regression model was used, which was estimated by the I² statistics. The quality of articles was evaluated by quality assessment of diagnostic accuracy studies (QUADAS).

Results

Thirteen articles including 2303 patients were qualified for the study. The pooled sensitivity and specificity of SWE for the diagnosis of liver fibrosis are as follows: ≥F1 0.76 (p<0.001, 95% CI, 0.71–0.81, I² = 75.33%), 0.92 (p<0.001, 95% CI, 0.80–0.97, I² = 79.36%); ≥F2 0.84 (p = 0.35, 95% CI, 0.81–0.86, I² = 9.55%), 0.83 (p<0.001, 95% CI, 0.77–0.88, I² = 86.56%); ≥F3 0.89 (p = 0.56, 95% CI, 0.86–0.92, I² = 0%), 0.86 (p<0.001, 95% CI, 0.82–0.90, I² = 75.73%); F4 0.89 (p = 0.24, 95% CI, 0.84–0.92, I² = 20.56%), 0.88 (p<0.001, 95% CI, 0.84–0.92, I² = 82.75%), respectively. Sensitivity analysis showed no significant changes if any one of the studies was excluded. Publication bias was not detected in this meta-analysis.

Conclusions

Our study suggests that SWE is a helpful method to appraise liver fibrosis severity. Future studies that validate these findings would be appropriate.

Influence of Food Intake on 2-D Shear Wave Elastography Assessment of Liver Stiffness in Healthy Subjects

Transient elastography and Acoustic Radiation Force Impulse imaging are useful non-invasive methods for liver stiffness estimation, although both are influenced by food intake. The aim of the work described here was to identify liver stiffness variation after a standardized meal using 2-D shear wave elastography. Liver stiffness was estimated in 31 apparently healthy subjects, under fasting conditions and after a standardized meal (20, 40, 60, 80, 100 and 120 min after food intake). In most of the cases, liver stiffness values increased between 20 and 40 min after the meal (p < 0.05) and then significantly decreased between 60 and 80 min (p < 0.05). At 120 min after food intake, liver stiffness values were significantly lower compared with liver stiffness values under fasting conditions (p < 0.05). Gender, but not body mass index, had an important role in liver stiffness variation after food intake (p < 0.01). In conclusion, to avoid the influence of food intake on liver stiffness estimation, 2-D shear wave elastography should be performed only under fasting conditions.

Diagnostic Accuracy of SuperSonic Shear Imaging for Staging of Liver Fibrosis: A Meta-analysis

OBJECTIVES

The purpose of this study was to assess the performance of SuperSonic shear imaging (SuperSonic Imagine SA, Aix-en-Provence, France) for diagnosis of liver fibrosis.

METHODS

Literature databases were searched to identify relevant studies from inception to February 28, 2015. Sensitivity, specificity, and other information were extracted from the studies. Pooled data were calculated by a bivariate mixed-effects binary regression model. Subgroup and sensitivity analyses were performed. Publication bias was tested by funnel plots.

RESULTS

Twelve studies were included in this meta-analysis and reported on 1635 patients. The pooled sensitivity and specificity were 0.78 (95% confidence interval [CI], 0.69-0.85) and 0.95 (95% CI, 0.75-0.99), respectively, for fibrosis stages F≥1, 0.84 (95% CI, 0.81-0.86) and 0.81 (95% CI, 0.74-0.87) for F≥2, 0.89 (95% CI, 0.85-0.93) and 0.84 (95% CI, 0.77-0.89) for F≥3, and 0.88 (95% CI, 0.82-0.91) and 0.86 (95% CI, 0.81-0.90) for F=4. The areas under the summary receiver operating characteristic curves were 0.87 (95% CI, 0.84-0.90) for F≥1, 0.85 (95% CI, 0.81-0.88) for F≥2, 0.93 (95% CI, 0.91-0.95) for F≥3, and 0.93 (95% CI, 0.90-0.95) for F=4. No significant publication bias was found.

CONCLUSIONS

SuperSonic shear imaging could be used for staging of liver fibrosis. Especially, it has high diagnostic accuracy for severe fibrosis and cirrhosis.

Sonoelastography of Plantar Fascia: Reproducibility and Pattern Description in Healthy Subjects and Symptomatic Subjects

The purpose of the work reported here was to describe the sonoelastographic appearance of the plantar fascia of healthy volunteers and patients with fasciitis. Twenty-three healthy subjects and 21 patients with plantar fasciitis were examined using B-mode and real-time sonoelastography (RTSR) scanning. B-Mode examination included fascia thickness and echotexture. Echogenicity and echovariation of the color histogram were analyzed. Fasciae were classified into type 1, blue (more elastic); type 2, blue/green (intermediate); or type 3, green (less elastic). RTSE revealed 72.7% of fasciae as type 2, with no significant association with fasciitis (χ(2) = 3.6, df = 2, p = 0.17). Quantitative analysis of the color histogram revealed a significantly greater intensity of green (mean = 77.8, 95% confidence interval [CI] = 71.9-83.6) and blue (mean = 74.2, 95% CI = 69.7-78.8) in healthy subjects. Echovariation of the color red was 33.4% higher in the fasciitis group than in the healthy group (95% CI = 16.7-50.1). Sonoelastography with quantitative analysis of echovariation can be a useful tool for evaluation of plantar fascia pathology.

Comparison of the Reliability of Acoustic Radiation Force Impulse Imaging and Supersonic Shear Imaging in Measurement of Liver Stiffness

PURPOSE

To compare the reliability of acoustic radiation force impulse (ARFI) imaging and supersonic shear imaging (SSI) in measurement of liver stiffness.

MATERIALS AND METHODS

This study was approved by the institutional review board, and written informed consent was obtained for all patients. Seventy-nine patients (25 healthy patients, 26 with Child-Pugh class A, and 28 with Child-Pugh class B or C) were enrolled and analyzed from April 2012 to April 2013. In each patient, three abdominal radiologists performed nine measurements of hepatic shear-wave speed with both ARFI imaging and SSI on the same day. Four weeks later, a second session was performed with the same protocol. Interobserver and intraobserver agreements were calculated by using intraclass correlation coefficients. Technical failures and measurement time were evaluated.

RESULTS

There were four technical failures in the SSI group and one in the ARFI group (P = .375). The overall interobserver agreement of ARFI imaging was significantly higher than that of SSI (0.941 vs 0.828, P < .001). The overall intraobserver agreement of ARFI imaging was significantly higher than that of SSI (0.915 vs 0.829, P < .001). The overall shear-wave speed measured with SSI was higher than that measured with ARFI imaging (2.04 m/sec ± 0.88 vs 1.80 m/sec ± 0.81, P < .001). The measurement time of SSI was longer than that of ARFI imaging (310.8 seconds ± 88.5 vs 84.5 seconds ± 15.4, P < .001).

CONCLUSION

ARFI imaging was more reliable than SSI in measurement of liver stiffness. The hepatic shear-wave speed measured with SSI was higher than that measured with ARFI imaging, which means that the shear-wave speeds measured with ARFI imaging and SSI cannot be used interchangeably.

Real-time shear-wave elastography: applicability, reliability and accuracy for clinically significant portal hypertension

BACKGROUND & AIMS

Real-time shear wave elastography (RT-SWE) might be useful to assess the severity of portal hypertension; reliability criteria for measurement are needed.

METHODS

We prospectively included 88 consecutive patients undergoing hepatic venous pressure gradient measurement (HVPG, reference standard) for portal hypertension. Liver stiffness (LS) was measured by RT-SWE and by transient elastography (TE). Spleen stiffness (SS) was measured by RT-SWE. Reliability criteria for RT-SWE were searched, and the accuracy of these techniques to identify HVPG ⩾10mmHg (clinically significant portal hypertension, CSPH) was tested and internally validated by bootstrapping analysis.

RESULTS

LS and SS by RT-SWE were feasible respectively in 87 (99%) and 58 (66%) patients. Both correlated with HVPG (LS: R=0.611, p<0.0001 and SS: R=0.514, p<0.0001). LS performed well for diagnosing CSPH (optimism corrected AUROC=0.858). Reliability of measurements was influenced by standard deviation (SD)/median ratio and depth. SD/median ⩽0.10 and depth of measurement <5.6cm were associated to 96.3% well classified for CSPH, while when one or none of the criteria were fulfilled the rates were 76.4% and 44.4%, respectively. Measurements fulfilling at least one criterion were considered acceptable; in these patients, RT-SWE performance to detect CSPH was excellent (AUROC=0.939; 95% CI: 0.865-1.000; p<0.0001; best cut-off: 15.4kPa). LS by RT-SWE and by TE were strongly correlated (R=0.795, p<0.0001) and performed similarly both in "per protocol" and in "intention-to-diagnose" analysis after applying reliability criteria.

CONCLUSIONS

LS by RT-SWE is an accurate method to diagnose CSPH if reliability criteria (SD/median ⩽0.10 and/or depth <5.6cm) are fulfilled.

Assessment of liver fibrosis: the relationship between point shear wave elastography and quantitative histological analysis

BACKGROUND AND AIM

Traditional pathological scoring systems for liver fibrosis progression are predominantly based on the description of architectural changes with no consideration of the amount of collagen fiber deposition. Our purpose was to explore a true histological standard in accordance with the liver stiffness measured by point shear wave elastography (PSWE) in patients with chronic hepatitis B.

METHODS

A total of 78 patients with liver neoplasms underwent liver stiffness measurements with PSWE as well as biochemical investigations within 3 days before partial hepatectomy. One tissue section of the liver specimens was stained with HE trichrome and evaluated traditionally with the Scheuer scoring system. The other tissue section was stained with picroSirius red and was evaluated according to the semiquantitative Chevallier et al. scoring system. In addition, this second tissue section was evaluated for the collagen proportionate area (CPA) with computer-assisted digital image analysis. The reproducibility of PSWE technology was explored through the intra-class correlation coefficient of a reliability analysis.

RESULTS

The PSWE technology revealed good reproducibility in liver stiffness measurements, and the PSWE values increased with the pathological severity of liver fibrosis on both the Scheuer scoring system and the semiquantitative Chevallier et al. scoring system. PSWE values exhibited more reasonable relationships with CPA (r = 0.628, P = 0.00 < 0.05) than with the Scheuer scoring system (r = 0.473, P = 0.00 < 0.05) or the Chevallier et al. semiquantitative scoring system (r = 0.487, P = 0.00 < 0.05).

CONCLUSION

CPA is a better pathological parameter than traditional semiquantitative scoring systems in accordance with liver stiffness measured by PSWE technology.

Strain US Elastography for the Characterization of Thyroid Nodules: Advantages and Limitation

Thyroid nodules, with their high prevalence in the general population, represent a diagnostic challenge for clinicians. Ultrasound (US), although absolutely reliable in detecting thyroid nodules, is still not accurate enough to differentiate them into benign and malignant. A promising novel modality, US elastography, has been introduced in order to further increase US accuracy. The purpose of this review article is to assess the thyroid application of US strain elastography, also known as real-time elastography or quasistatic elastography. We provide a presentation of the technique, and of up-to-date literature, analyzing the most prominent results reported for thyroid nodules differentiation. The practical advantages and limitations of strain elastography are extensively discussed herein.