Evaluation of acoustic radiation force impulse elastography for fibrosis staging of chronic liver disease: a pilot study

Background Acoustic radiation force impulse (ARFI) is a new technology integrated into conventional B-mode ultrasonography. ARFI is used to evaluate tissue stiffness in several organs, but this method has not been applied for liver fibrosis. Aim The aim of this study was to determine whether ARFI elastography is useful for the evaluation of liver fibrosis. Methods This study enrolled 55 consecutive patients with chronic liver disease who underwent a liver biopsy for histological assessment of liver fibrosis by the Metavir scoring system. Liver stiffness of the 55 patients and 25 healthy volunteers was evaluated by ARFI elastography and was expressed as the shear wave velocity. Cut-off values were determined using receiver-operating characteristic (ROC) curves. Results Histological liver fibrosis was evaluated by Metavir scoring; F0: six cases, F1: 14 cases, F2: nine cases, F3: nine cases and F4: 17 cases. Liver stiffness determined by ARFI elastography was correlated with histological liver fibrosis (P < 0.0001). The areas under the ROC curves were 0.94 (95% confidence intervals, 0.87-0.99) for F2-F4, 0.94 (0.88-0.99) for F3-F4 and 0.96 (0.91-1.01) for F4. The cut-off values of the shear wave velocity were as follows: > 1.34 m/s for F2-F4 (sensitivity 91.4%, specificity 80%); > 1.44 m/s for F3-F4 (sensitivity 96.2%, specificity 79.3%); and > 1.80 m/s for F4 (sensitivity 94.1%, specificity 86.8%). Conclusions Ultrasonic ARFI elastography is a novel, non-invasive and reliable method for the assessment of liver fibrosis in patients with chronic liver disease.