Acoustic radiation force impulse: a new ultrasonographic technology for the widespread noninvasive diagnosis of liver fibrosis

Background/aims As a module of a standard ultrasound imaging device, acoustic radiation force impulse (ARFI) is a new technology for liver stiffness evaluation (LSE). We aimed to evaluate accuracy, feasibility, reproducibility, and training effect of ARFI for liver fibrosis evaluation. Methods One hundred and one patients with chronic liver disease had LSE by Fibroscan and ARFI. LSE by ARFI was performed in the two liver lobes by two operators: an expert and a novice. Correlation and agreement were evaluated by the Pearson (Rp) and intraclass (Ric) correlation coefficients. The independent reference for liver fibrosis was fibrosis blood tests. Results ARFI results, ranging from 0.7 to 4.6 m/s, were well correlated with Fibroscan results (Rp = 0.76). Fibroscan had a significantly higher area under the receiver operating characteristic curve (AUROC) than ARFI for the perprotocol diagnosis of significant fibrosis: 0.890 +/- 0.034 versus 0.795 +/- 0.047 (P=0.04). However, LSE failure occurred in zero patients using ARFI versus six patients using Fibroscan (P=0.03). Thus, on an intention-to-diagnose basis, Fibroscan and ARFI AUROCs for the diagnosis of significant fibrosis were not different: 0.791 +/- 0.049 versus 0.793 +/- 0.046 (P=0.98). Interobserver agreement was very good (Ric=0.84) and excellent for ARFI interquartile range (IQR) <= 0.30 (Ric = 0.91). Indeed, agreement was independently predicted only by ARFI IQR, but not by LSE result as earlier observed for Fibroscan. ARFI AUROC was 0.876 +/- 0.057 in patients with ARFI IQR ratio <= 0.30, and Fibroscan AUROC was 0.912 +/- 0.034 in patients with Fibroscan IQR ratio less than 0.21 (P=0.59). Intersite ARFI agreement between the two liver lobes was fair (Ric=0.60). There was no training effect for LSE by ARFI. Conclusion ARFI is highly feasible and reproducible, and provides diagnostic accuracy similar to Fibroscan. This new device seems noteworthy for the widespread noninvasive diagnosis of liver fibrosis. Eur J Gastroenterol Hepatol 22: 1074-1084 (C) 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.