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Objectives: The primary aim was to estimate the influence of various depths on ultrasound attenuation coefficient (AC) of multiple vendors in the liver. The secondary aim was to evaluate the impact of region of interest (ROI) size on AC measurements in a subset of participants. Methods: This Institutional Review Board (IRB)‐approved Health Insurance Portability and Accountability Act (HIPAA)‐compliant retrospective study was carried out in two centers using AC‐Canon and AC‐Philips algorithms and extracting AC‐Siemens values from ultrasound‐derived fat fraction algorithm. Measurements were performed positioning ROI upper edge (3 cm size) at 2, 3, 4, 5 cm from the liver capsule with AC‐Canon and AC‐Philips and at 1.5, 2, 3 cm with Siemens algorithm. In a subset of participants, measurements were obtained with 1 and 3 cm ROI size. Univariate and multivariate linear regression models and Lin's concordance correlation coefficient (CCC) were used for statistical analysis as appropriate. Results: Three different cohorts were studied. Sixty‐three participants (34 females; mean age: 51 ± 14 years) were studied with AC‐Canon, 60 (46 females; mean age: 57 ± 11 years) with AC‐Philips, and 50 (25 females; 61 ± 13 years) with AC‐Siemens. There was a decrease in AC values per 1 cm increase in depth in all. In multivariable analysis, the coefficient was −0.049 (−0.060; −0.038 P <.001) with AC‐Canon, −0.058 (−0.066; −0.049 P <.001) with AC‐Philips and −0.081 (−0.112; −0.050 P <.001) with AC‐Siemens. AC values with 1 cm ROI were significantly higher than those obtained with 3 cm ROI at all depths (P <.001) but the agreement between AC values obtained with different ROI size was excellent (CCC 0.82 [0.77–0.88]). Conclusions: There is depth dependence in AC measurement that affects results. A standardized protocol with fixed ROI's depth and size is needed. [ABSTRACT FROM AUTHOR]

Background & Aims Ultrasound is the imaging modality most widely utilized in the general population for diagnostic purposes. Controlled attenuation parameter is a novel noninvasive method for assessing steatosis. Our aim was to investigate whether the clinical value of controlled attenuation parameter in patients referred for abdominal ultrasound examinations is affected by liver fibrosis. Methods Consecutive patients referred for abdominal ultrasound examinations were enrolled. Controlled attenuation parameter and liver stiffness were assessed with the FibroScan (Echosens, France). Liver fibrosis was staged according to published cutoffs of liver stiffness measurements. Pearson's or Spearman's rank correlation coefficient was used to test the association between two study variables. Optimal cutoff of controlled attenuation parameter for diagnosing liver steatosis (S≥2) was 256 dB/m. The diagnostic performance and accuracy of dichotomized controlled attenuation parameter, ultrasound and body mass index were analysed using the imperfect gold standard methodology. Results A total of 726 subjects (464 males and 262 females) were studied. Five hundred and eight-nine (81.1%) patients were affected by chronic viral hepatitis. Correlation of controlled attenuation parameter with ultrasound score was 0.48 and 0.57 in patients with and without chronic viral hepatitis respectively. In patients with chronic viral hepatitis, ultrasound, dichotomized controlled attenuation parameter and body mass index showed performance of 58.2%, 82.3% and 46.7%, respectively, whereas in patients without chronic viral hepatitis, the performance was 86.4%, 68.6% and 48.6% respectively. Conclusions In patients with chronic viral hepatitis and advanced liver fibrosis, controlled attenuation parameter performs better than ultrasound for assessing liver steatosis, whereas in patients without viral hepatitis and with nonsignificant liver disease ultrasound shows the best performance. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To evaluate the reproducibility of real-time shear wave elastography in assessing liver elasticity in healthy volunteers. Methods: Forty-two volunteers were studied in day 1. Shear wave elastography studies were performed by using the ultrasound system Aixplorer™ (SuperSonic Imagine S.A., Aix-en-Provence, France) with a convex broadband probe. Measurements were carried by two operators, an expert (operator 1) and a novice (operator 2). Examinations were performed on the right lobe of the liver. Each operator performed 10 consecutive measurements in each volunteer. In a subset of volunteers (n =18) measurements were performed twice on two different days (day 1 and day 2). Intraobserver and interobserver agreement were assessed by intraclass correlation coefficient. Results: Intraobserver agreement between measurements performed in the same subject in the same day (day 1 or day 2) showed intraclass correlation coefficient values of 0.95 (95% confidence interval, 0.93–0.98) and 0.93 (95% confidence interval, 0.90–0.96) for operator 1 and operator 2, respectively. Intraobserver agreement between measurements performed in the same subject in different days showed intraclass correlation coefficient values of 0.84 (95% confidence interval, 0.69–0.98) and 0.65 (95% confidence interval, 0.39–0.91) for operator 1 and operator 2, respectively. Interobserver agreement was 0.88 (95% confidence interval, 0.82–0.94). Conclusions: The results of this study show that shear wave elastography is a reliable and reproducible noninvasive method for the assessment of liver elasticity. Expert operator had higher reproducibility of measurements over time than novice operator. [Copyright &y& Elsevier]