Objectives: Ultrasound shear wave elastography (SWE) is an imaging technique that quantifies liver stiffness. However, comparison data across newest ultrasound systems are sparse. The purpose of this study was to assess repeatability and agreement of shear wave speeds (SWSs) across 6 ultrasound 2-dimensional (2D) SWE systems.
Materials and methods: This cross-sectional, Health Insurance Portability and Accountability Act-compliant study received institutional review board approval. Written informed consent was obtained. Serial 2D SWE examinations were performed with 6 ultrasound systems (Aplio i800, Canon Medical Systems; LOGIQ E10, GE Healthcare; Resona 7, Mindray North America; EPIQ Elite, Philips Healthcare; ACUSON Sequoia, Siemens Medical Solutions; and Aixplorer MACH 30, SuperSonic Imagine) on 4 elastic phantoms (SWS range, 0.82-3.51 m/s) and on livers of 24 adults (healthy volunteers and patients with known liver stiffening). Participants were imaged 2 times per ultrasound system, with 90 to 120 minutes between examinations. Median SWS was calculated from separately acquired SWS measurements per examination (40 phantom measurements and 10 liver measurements per examination).
Results: Overall intraclass correlation coefficient (ICC) for intersystem agreement of median SWS across systems was 0.99 (95% confidence interval, 0.96-1.0) in phantoms and 0.66 to 0.69 (95% confidence interval, 0.47-0.84) in humans across systems. Means of median SWS measurements in humans ranged from 1.24 to 1.56 m/s. Average individual subject-level variance (interquartile range/median SWS) across all examinations was 0.07, with an average coefficient of variation of 6.0%. Pairwise ICCs for intersystem agreement in subjects across systems ranged from 0.41 to 0.91; test-retest repeatability in subjects was excellent for all systems, with ICCs ranging from 0.87 to 0.97.
Conclusions: There is good to excellent intersystem agreement of measured SWS in elastic phantoms and in vivo livers across 6 ultrasound 2D SWE systems. Test-retest repeatability was excellent for all systems.