Comparing acoustic radiation force impulse imaging to transient elastography to assess liver stiffness in healthy volunteers with and without valsalva manoeuvre.

PURPOSE Acoustic Radiation Force Impulse Imaging (ARFI) is a new ultrasound elastography technology (Siemens ACUSON S2000 Virtual Touch™ Tissue Quantification), which is integrated in conventional ultrasound equipment. In preliminary studies, ARFI sheer wave speed (SWS) in liver tissue correlated well with transient elastography (TE) values and liver fibrosis stages. MATERIALS AND METHODS Sixty-eight healthy male and female volunteers were measured with ARFI with two ultrasound tranducers, three measuring positions and during valsalva manoeuvre. A TE (FibroScan™, Echosens, France) was performed in 60 volunteers. RESULTS Volunteers had a mean age of 28 years and a mean BMI of 22.3. There was no significant difference of ARFI SWS between the 4C1 and 4V1 ultrasound probes in either intercostal or abdominal approach to liver segment 8 but a higher variance of ARFI SWS with the 4V1/abdominal compared to the intercostal approach (p = 0.0368). The 4C1/intercostal approach had the highest success rates (97.2%), comparable to those of TE (97.18%). Left liver lobe measurements obtained both significantly higher ARFI SWS and value variance (p = 0.0016 and p = 0.0198) compared to 4C1/intercostal approach. Mean ARFI SWS was 1.19 m/s (range 0.77-1.63). Mean TE was 5.39 kPa (range 3.3-9.0 kPa). Valsalva manoeuvre did not significantly alter ARFI SWS and variance. Skin-liver distance significantly influenced ARFI SWS (p < 0.05), while age and gender did not. CONCLUSION These results might constitute a first impression of the chances of ARFI SWS to assess liver stiffness, especially in patients with liver diseases due to increased venous pressure.