Liver Stiffness Measurement Using Acoustic Radiation Force Impulse (ARFI) Elastography and Effect of Necroinflammation

Acoustic radiation force impulse (ARFI) elastography can be used to assess the degree of liver fibrosis. We evaluated the performance of ARFI elastography in assessment of liver fibrosis and compared it with the performance of aspartate aminotransferase-to-platelet ratio index (APRI) and transient elastography with Fibroscan (FS). We prospectively analyzed 250 consecutive patients who underwent liver biopsy and ARFI from June 2010 to May 2011. Reliable FS values were obtained for 97 (38.8%) patients. The mean age of patients (147 male and 103 female) was 46.6 years. Liver stiffness values obtained by use of ARFI elastography significantly correlated with histological fibrosis stage (R = 0.575, P < 0.001). Area under the receiver operating characteristics curves (AUROCs) of ARFI elastography for predicting significant fibrosis (a parts per thousand yenF2) and cirrhosis (F4) was 0.74 (95% confidence interval [CI], 0.64-0.86, P = 0.001) and 0.79 (95% CI, 0.67-0.91, P = 0.001), respectively, and those for APRI were 0.69 (95% CI, 0.58-0.79, P = 0.001) and 0.76 (95% CI, 0.64-0.85, P < 0.001), respectively. The optimum cutoff values for ARFI elastography were 1.13 m/s for a parts per thousand yenF2 and 1.98 m/s for F4; these decreased to 1.09 m/s for a parts per thousand yenF2 and 1.81 m/s for F4 when 131 patients with normal alanine aminotransferase (ALT) were selected. In the sub-group of 97 patients with reliable FS values, the performance in predicting a parts per thousand yenF2 or F4 was equivalent between ARFI elastography and FS. ARFI elastography is a reliable surrogate marker of liver fibrosis, if its relationship with biochemical markers, for example ALT level, is taken into account.