Correlation between non-invasive markers of fibrosis with shear wave elastography and AFI among adult patients diagnosed with NAFLD biopsy

Background: Shear wave elastography (SWE) and acoustic radiation force impulse (ARFI) are novel non-invasive ultrasound-based imaging studies which have enabled clinicians to assess the degree of fibrosis among patients with chronic liver disease. Data on the use of these diagnostic studies among patients with non-alcoholic fatty liver disease (NAFLD) are few. This study aims to determine the sensitivity and specificity of SWE and ARFI elastography in determining fibrosis among patients with NAFLD.

Methods: Review of medical records was done among patients with biopsy-proven NAFLD at St. Luke’s Medical Center, Quezon City from January 2007 and October 2012. Imaging studies (SWE and ARFI) were compared to histopathologic results to compute for sensitivity and specificity. Analysis of receiver operating characteristics (ROC) were also done to calculate the area under the curve (AUC) for both imaging studies.

Results: A total of 106 patients with biopsy-proven NAFLD were included. Among these patients 56 had ARFI and 48 had SWE. ARFI had 70% sensitivity, 57% specificity, 41.4% positive predictive value and 85.2% negative predictive value, while SWE had 53.3% sensitivity, 90.9% specificity, 72.2% positive predictive value and 81.1% negative predictive value. The AUC of SWE was 0.845 and ARFI was 0.739. Subgroup analysis using Pearson’s correlation and regression analysis comparing SWE and ARFI with histologic grade (SWE 0.57, p<0.001; ARFI: 0.54, p<0.001), non-invasive clinical scoring (SWE 0.48, p<0.001; ARFI 0.38, p,0.001) and FIB-4 (SWE 0.65, p<0.001; ARFI 0.44, p<0.001) for fibrosis revealed positive correlation.

Conclusion: Non-invasive ultrasound-based SWE and ARFI are useful diagnostic tests in assessing fibrosis among NAFLD patients with ARFI showing more sensitivity and SWE showing more specificity. Both SWE and ARFI showed significant postiive correlation among biopsy-poven NAFLD patients.