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

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.