Influence of Measurement Depth on the Stiffness Assessment of Healthy Liver with Real-Time Shear Wave Elastography

Abstract

The purpose of this study was to determine the measurement depth range within which liver stiffness can be reliably assessed using real-time shear wave elastography (SWE) technology. Measurements were performed on phantoms and healthy volunteers. In the first group of patients, measurements were performed at depths of 2–8 cm from the probe surface. In the second group of patients, measurements were conducted 0–7 cm below the liver capsule. Success rate of measurements (SRoM), success rate of patients (SRoS) and coefficients of variation (CVs) of repeated measurements were compared. The SRoMs at 3–7 cm and the CVs at 2–5 cm from the probe surface were significantly higher and lower than those at other depths (p < 0.001), respectively. SRoS was zero 0–1 cm below the liver capsule. Furthermore, the features of 2-D stiffness mapping images were also found to change with depth. According to our results, the depth range for the most reliable liver stiffness assessment using SWE should be 3–5 cm from the probe surface and simultaneously 1–2 cm below the liver capsule.