Background/aims: Acoustic radiation force impulse (ARFI) imaging is a new technology for performing liver elastography. However, use of this technique to estimate the degree of fibrosis in chronic liver disease (CLD) related to hepatitis C virus (HCV) infection has not yet been established. We evaluated the validity, accuracy and flexibility of the ARFI method in CLD.
Methodology: Subjects comprised 30 patients with chronic hepatitis (CH), 30 patients with liver cirrhosis (LC) and 10 healthy subjects (controls). All patients had HCV infection. Elastography of the liver was performed at different sites using the ARFI method. Relationships between shear wave velocity (SWV) obtained by ARFI, clinical diagnosis, serum parameters of liver function and fibrosis in the liver were evaluated. Moreover, cut-off values for differential diagnosis between CH and LC were estimated using area under the receiver operating characteristics (AUROC).
Results: Mean SWV (+/- standard deviation) was 2.67 +/- 1.18 m/s, 1.33 +/- 0.54 m/s and 0.99 +/- 0.21 m/s in the LC, CH and control groups, respectively. SWV was significantly higher in the LC group than in the CH and control groups (p < 0.0001), and in the CH group than in the control group (p = 0.0023). SWV in each stage of fibrosis was 1.09 +/- 0.22 m/s in F0-1, 1.24 +/- 0.52 m/s in F2, 1.61 +/- 0.79 m/s in F3, and 2.35 +/- 1.11 m/s in F4. SWV correlated significantly with serum total bilirubin, alanine aminotransferase, cholesterol, albumin, platelet counts, prothrombin time, fibrosis markers, hyaluronic acid and type IV collagen. A steady stepwise increase in elasticity correlated significantly with severity of hepatic fibrosis (p = 0.9772; p = 0.002). Diagnostic ability for LC was superior in ARFI (AUROC, 0.930 in ARFI; 0.846 in aspartate aminotransferase to platelet ratio index; 0.829 in Forns' index; and 0.785 in platelet count).
Conclusions: ARFI is extremely useful for distinguishing between CH and LC, and SWV might correlate significantly with degree of progression in CLD with HCV infection.