Noninvasive Assessment of Liver Fibrosis with Acoustic Radiation Force Impulse Imaging: Increased Liver and Splenic Stiffness in Patients with Liver Fibrosis and Cirrhosis

Purpose: To evaluate acoustic radiation force impulse imaging (ARFI) of the liver and spleen as a new method for the noninvasive assessment of liver fibrosis (LF). Materials and Methods: Three groups of 58 examinees were studied: (A) 20 healthy volunteers; (B) 18 patients with chronic viral hepatitis (CVH) B or C having liver fibrosis stages F1 -4 (assessed by liver biopsy; Ishak classification); and (C) 20 patients with liver cirrhosis (LC). All participants were examined using the Siemens ACUSON S2000 Ultrasound Virtual Touch Tissue Quantification (TM) system. Ten measurements were performed on both liver lobes and three measurements on the spleen, and the obtained mean values (shear wave velocities [SWV] expressed in m/s) were compared between the groups. In 20 patients the splenic artery pulsatility index (SAPI) was also measured and correlated to the liver and splenic ARFI and histological stage of LF. Results: Hepatic ARFI measurements demonstrated a significant correlation to LB results (Spearman's p = 0.766; p<0.001) and SWV cut-off values of 1.3 (AUC 0.96) and 1.86 (AUC 0.99) could reliably differentiate between healthy (A) and non-cirrhotic CVH (B), as well as between non-cirrhotic CVH (B) and LC (C). Splenic SWV cut-off value of 2.73 (AUC 0.82) could differentiate between the patients with LC and non-cirrhotic CVH. A significant correlation was also observed between the SAPI and liver ARFI results (p = 0.56; p= 0.013). Conclusion: The hepatic and splenic SWV measured by ARFI increase with the LF stage, and the hepatic SWV correlate well with SAPI. This new technology enables simultaneous morphological, Doppler and elastometric examinations and might improve the accuracy of noninvasive liver fibrosis assessment.