Evaluation of Inter-System Variability in Liver Stiffness Measurements

• Published in: Ultraschall in der Medizin Vol. 40; no. 1; p. 64
• Main Authors: Ferraioli, Giovanna, De Silvestri, Annalisa, Lissandrin, Raffaella, Maiocchi, Laura, Tinelli, Carmine, Filice, Carlo, Barr, Richard G
• Format: Journal Article
• Language: English
• Published: Germany 01-02-2019
• Subjects: Case-Control Studies; Elasticity Imaging Techniques; Hepatitis C, Chronic - diagnostic imaging; Humans; Liver; Observer Variation; Reproducibility of Results
• ISSN: 1438-8782
• DOI: 10.1055/s-0043-124184

The primary aim of this study was to determine the inter-system variability of liver stiffness measurements (LSMs) in patients with varying degrees of liver stiffness. The secondary aim was to determine the inter-observer variability of measurements.
 21 individuals affected by chronic hepatitis C and 5 healthy individuals were prospectively enrolled. The assessment of LSMs was performed using six ultrasound (US) systems, four of which with point shear wave elastography (p-SWE) and two with 2 D shear wave elastography (2D-SWE) systems. The Fibroscan (Echosens, France) was used as the reference standard. Four observers performed the measurements in pairs (A-B, C-D). The agreement between different observers or methods was calculated using Lin's concordance correlation coefficient. The Bland-Altman limits of agreement (LOA) were calculated as well.
 There was agreement above 0.80 for all pairs of systems. The mean difference between the values of the systems with 2D-SWE technique was 1.54 kPa, whereas the maximum mean difference between the values of three out of four systems with the pSWE technique was 0.79 kPa. The intra-patient concordance for all systems was 0.89 (95 % CI: 0.83 - 0.94). Inter-observer agreement was 0.96 (95 % CI: 0.94 - 0.98) for the pair of observers A-B and 0.93 (95 % CI: 0.89 - 0.96) for the pair of observers C-D.
 The results of this study show that the agreement between LSMs performed with different US systems is good to excellent and the overall inter-observer agreement in "ideal conditions" is above 0.90 in expert hands.