Diagnostic of hepatic fibrosis with the XL probe of the Fibroscan versus biopsies in patients candidates to bariatric surgery.

BACKGROUND AND AIMS: The risks of the histological evaluation for metabolic liver disease in severe obese subjects led to the development of the Fibroscan® device. The main objective of our study is to evaluate the diagnostic performance of XL probe for the measurement of hepatic fibrosis compared to histological examination, in obese subjects operated from bariatric surgery. METHODS: We included patients free from chronic liver diseases. Liver measurement and controlled attenuation parameter (CAP) were carried out using the Fibroscan®. Liver biopsies were performed during bariatric surgery and evaluated by two pathologists. Correlation between vibration-controlled transient elastography (VCTE) and fibrosis stage was assessed using the Kendall correlation coefficient. Diagnosis performance was assessed using receiver-operating-characteristic curve analysis together with its 95% confidence interval. Cut-off value maximizing the Youden index was computed together with specificity, sensitivity, positive and negative predictive values. RESULTS: The average age and body mass index were 41 years and 43 kg/m2, respectively (n = 108). Forty-one percent of patients presented fibrosis on the histological results. The Kendall correlation coefficient between fibrosis stage and liver stiffness measurement (LSM) was κ = 0.33, p<10-5. ROC analysis for the detection of fibrosis indicated the following values: 0.70 [0.60-0.79] for F≥1, 0.83 [0.72-0.92] for F≥2, 0.90 [0.83-0.97] for F≥3. Optimal cut-offs maximizing the Youden index were 7.0 kPa for F≥1, 8.1 kPa for F≥2 and 8.7 kPa for F≥3. CONCLUSION: Fibroscan® appears to be reliable for detection of significant and severe fibrosis in severe obese patients such as candidates for bariatric surgery. CLINICAL TRIAL NUMBER: NCT03548597.

Novel controlled attenuation parameter for noninvasive assessment of steatosis using Fibroscan(®): validation in chronic hepatitis C.

A novel controlled attenuation parameter (CAP) has been developed for Fibroscan(®) to assess liver steatosis, simultaneously with liver stiffness measurement (LSM). We assessed CAP diagnostic accuracy in a large cohort of patients with chronic hepatitis C (CHC) virus. A total of 615 patients with CHC, who underwent both Fibroscan(®) and liver biopsy, were analysed. Fibrosis was graded using METAVIR score. Steatosis was categorized by visual assessment as S(0) : steatosis in <10% of hepatocytes, S(1) : 11-33%, S(2) : 34-66% and S(3) : 67-100%. Performances of CAP and liver stiffness were determined using receiver operating characteristic (ROC) curve analysis and cross-validated using the bootstrap method. The Obuchowski measure was used to assess overall accuracy of CAP and to differentiate between steatosis grades. In multivariate analysis, CAP was related to steatosis (P < 10(-15) ) independently of fibrosis stage (which was related to LSM). The areas under ROC curves using CAP to detect steatosis were 0.80 (95% CI, 0.75-0.84) for S ≥ S(1) , 0.86 (0.81-0.92) for S ≥ S(2) and 0.88 (0.73-1) S = S(3) . CAP exhibited a good ability to differentiate steatosis grades (Obuchowski measure = 0.92). Performance of LSM for fibrosis assessment confirmed results from previous studies. CAP is a novel tool to assess the degree of steatosis and both fibrosis and steatosis can be evaluated noninvasively during the same procedure using Fibroscan(®) , in patients with CHC.

The controlled attenuation parameter (CAP): a novel tool for the non-invasive evaluation of steatosis using Fibroscan.

Steatosis is a reversible and benign condition. However, in a few cases, steatosis is associated with inflammation and hepatocyte changes, and is then defined as steato-hepatitis. Steatosis can also be a co-factor in many chronic liver diseases that can lead to fibrosis and cirrhosis. Although an important parameter, until now, evaluation of steatosis by non-invasive methods has remained challenging. In this paper, we report on the use of a novel non-invasive methodology called a controlled attenuation parameter (CAP). This is based on signals acquired by the Fibroscan, which was developed to specifically assess liver steatosis concomitant to liver stiffness measurements (LSM). CAP's performance from published articles and communications is also reported.

Copolymer-in-oil phantom materials for elastography.

Phantoms that mimic mechanical and acoustic properties of soft biological tissues are essential to elasticity imaging investigation and to elastography device characterization. Several materials including agar/gelatin, polyvinyl alcohol and polyacrylamide gels have been used successfully in the past to produce tissue phantoms, as reported in the literature. However, it is difficult to find a phantom material with a wide range of stiffness, good stability over time and high resistance to rupture. We aim at developing and testing a new copolymer-in-oil phantom material for elastography. The phantom is composed of a mixture of copolymer, mineral oil and additives for acoustic scattering. The mechanical properties of phantoms were evaluated with a mechanical test instrument and an ultrasound-based elastography technique. The acoustic properties were investigated using a through-transmission water-substituting method. We showed that copolymer-in-oil phantoms are stable over time. Their mechanical and acoustic properties mimic those of most soft tissues: the Young's modulus ranges from 2.2-150 kPa, the attenuation coefficient from 0.4-4.0 dB.cm(-1) and the ultrasound speed from 1420-1464 m/s. Their density is equal to 0.90 +/- 0.04 g/cm3. The results suggest that copolymer-in-oil phantoms are attractive materials for elastography.