Objectives: Noninvasive tests for the evaluation of liver fibrosis are particularly helpful in children to avoid general anesthesia and potential complications of invasive tests. We aimed to establish reference values for 2 different elastography methods in a head-to-head comparison for children and adolescents 4 to 17 years, using transient elastography as common reference in a subset. Methods: A total of 243 healthy participants aged 4 to 17 years were examined by a single observer with a full liver B-mode scan before elastography, following a minimum of 3 hours fasting. Liver stiffness measurements (LSMs) using 2-dimensional shear wave elastography (2D-SWE, GE Logiq E9) and point shear wave elastography (pSWE, Samsung RS80A with Prestige) were performed in all participants, and compared to transient elastography (TE, FibroScan) in a subset (n = 87). Interobserver agreement was evaluated in 50 children aged 4 to 17 years. Results: Valid measurements were obtained in 242 of 243 (99.6%) subjects for 2D-SWE, 238 of 243 (97.9%) for pSWE, and in 83 of 87 (95.4%) for TE. Median liver stiffness overall was 3.3 (interquartile range [IQR] 2.7–4.3), 4.1 (IQR 3.6–4.7), and 4.1 kPa (IQR 3.5–4.6) for 2D-SWE, pSWE, and TE, respectively. Intraclass correlation coefficients between observers were 0.84 and 0.83 for 2D-SWE and pSWE, respectively. LSM values were significantly lower for 2D-SWE compared to pSWE and TE, and increased with advancing age. Higher LSM values in males were observed in adolescents. Conclusions: All methods showed excellent feasibility. 2D-SWE showed significantly lower LSM values than pSWE and TE, and lower failure rate compared to TE. Our results further indicate an age and sex effect on LSM values.

ObjectiveEstablishing normal liver stiffness (LS) values in healthy livers is a prerequisite to differentiate normal from pathological LS values. Our aim was to define normal LS using two novel elastography methods head-to-head and to assess the number of measurements, variability and reproducibility.Materials and methodsWe evaluated shear wave elastography (SWE) methods integrated in Samsung RS80A and GE S8 by obtaining LS measurements (LSM) in 100 healthy subjects (20–70 years). Transient Elastography (TE) was used as reference method. Data were analyzed according to age, sex, BMI and 5 vs. 10 measurements. All subjects underwent B-mode ultrasound examination and lab tests to exclude liver pathology. Interobserver variation was evaluated in a subset (n = 24).ResultsBoth methods showed excellent feasibility, measuring LS in all subjects. LSM-mean for GE S8 2D-SWE was higher compared to TE (4.5±0.8 kPa vs. 4.2±1.1, p<0.001) and Samsung RS80A (4.1±0.8 kPa, p<0.001). Both methods showed low intra- and interobserver variation. LSM-mean was significantly higher in males than females using 2D-SWE, while a similar trend for Samsung SWE did not reach significance. No method demonstrated statistical significant difference in LSM across age and BMI groups nor between LSM-mean based on 5 vs. 10 measurements.ConclusionLSM was performed with high reproducibility in healthy adult livers. LSM-mean was significantly higher for GE S8 2D-SWE compared to Samsung RS80A and TE in healthy livers. Males had higher LSM than females. No method demonstrated statistical significant difference in LSM-mean across age- and non-obese BMI groups. Our results indicate that five LSM may be sufficient for reliable results.

This study aimed to assess and validate the repeatability and agreement of quantitative elastography of novel shear wave methods on four individual tissue-mimicking liver fibrosis phantoms with different known Young’s modulus. We used GE Logiq E9 2D-SWE, Philips iU22 ARFI (pSWE), Samsung TS80A SWE (pSWE), Hitachi Ascendus (SWM) and Transient Elastography (TE). Two individual investigators performed all measurements non-continued and in parallel. The methods were evaluated for inter- and intraobserver variability by intraclass correlation, coefficient of variation and limits of agreement using the median elastography value. All systems used in this study provided high repeatability in quantitative measurements in a liver fibrosis phantom and excellent inter- and intraclass correlations. All four elastography platforms showed excellent intra-and interobserver agreement (interclass correlation 0.981–1.000 and intraclass correlation 0.987–1.000) and no significant difference in mean elasticity measurements for all systems, except for TE on phantom 4. All four liver fibrosis phantoms could be differentiated by quantitative elastography, by all platforms (p<0.001). In the Bland-Altman analysis the differences in measurements were larger for the phantoms with higher Young’s modulus. All platforms had a coefficient of variation in the range 0.00–0.21 for all four phantoms, equivalent to low variance and high repeatability.