Acoustic radiation force impulse accuracy and the impact of hepatic steatosis on liver fibrosis staging

Introduction: The accuracy of Acoustic Radiation Force Impulse (ARFI) imaging has been validated in the setting of hepatitis C, however, the accuracy in the setting of fatty liver disease (FLD) has been less well-established. The aim of this study was to assess the accuracy of ARFI in the setting of hepatic steatosis. Methods: Patients with biopsy proven or sonographically diagnosed liver steatosis were assessed for ARFI trends including: inter-operator concordance, interquartile range, ARFI failure rate, relationship between ARFI velocity and steatosis severity, and concordance between biopsy and ARFI fibrosis scores. Results: Three hundred and forty-nine patients were assessed (53 ‘biopsy’ cohort and 296 ‘ultrasound’ cohort), with 28 patients having biopsy on the same day as ARFI. Low stages of fibrosis (F0/1) were over-estimated by ARFI in 62% of cases with biopsy correlation (n = 16, P < 0.001), with ARFI offering increased accuracy in regard to higher-stage fibrosis (14/15 cases, 93%). In both the biopsy and ultrasound cohorts the failure rate and median inter-quartile range increased with increasing steatosis, and the inter-operator concordance remained good across all liver steatosis severities. Conclusion: In the setting of steatosis, ARFI is very sensitive in detecting, and accurate in diagnosing, higher stages of fibrosis regardless of steatosis severity. It tends to overestimate the fibrosis category in lower stages of fibrosis. The present study does not show conclusively if the presence of steatosis or its severity independently alters ARFI measurements.