Application of 2D shearwave elastography for screening of NAFLD in people with class 3 obesity

Abstract

INTRODUCTION: Early and accurate detection of significant liver fibrosis allows timely management of cirrhosis and related comorbidities. Liver biopsy, the diagnostic gold standard, is invasive and risks complications. Non-invasive methods such as 2D Shear Wave Elastography (SWE) are increasingly being used, but the presence of severe obesity could lead to technical difficulties. This study aimed to assess the applicability of SWE in screening for non-alcoholic fatty liver disease (NAFLD) associated liver fibrosis in people with class 3 obesity. MATERIALS AND METHODS: This was a cross-sectional study conducted in a publicly funded, multidisciplinary weight management program in Sydney, Australia. All patients enrolled between February 2021 and February 2022, who had at least one physician appointment, were included. Participants were aged ≥ 18 years with body mass index (BMI) ≥ 40 kg/m2 and at least one weight-related medical comorbidity. A Fibrosis-4 (FIB-4) index score of 1.45 and AST to Platelet Ratio Index (APRI) score of 0.7 were considered as cut-off scores for significant fibrosis. SWE was performed by a single operator using Acoustic Radiation Force Impulse (ARFI) ultrasound system enabled with ElastPQ imaging (EQI) SWE. EQI liver stiffness values were calculated to estimate the likelihood of liver fibrosis, and 6.43 kPa was considered as cut-off score for significant fibrosis. RESULTS: The mean (SD) weight of participants (n = 50; age 47.9 (13.9) years; 59% females; 68% Caucasians; 56% Type 2 diabetes, 23% Hypertension, 6% known NAFLD) was 148.4 (29.7) kg with a BMI of 51.5 (8.7) kg/m2. A Liver EQI was obtained for all elastography scans in spite of their high BMI, with a reliability indicator (Liver EQI IQR/Med) below 30%, indicating that all tests were reliable for reporting. The mean Liver EQI Med value was 5.1 (1.2) kPa, mean FIB-4 score was 0.9 (0.5), and mean APRI score was 0.2 (0.1). Using SWE, 2/50 participants had a liver-stiffness value above cut-off score for significant fibrosis. There was a positive correlation between Liver EQI Med value and FIB-4 score (r = 0.451, p = 0.003) and APRI score (r = 0.337, p = 0.029). FIB-4 score had a statistically significant positive correlation with age (r = 0.671, p < 0.001) and APRI score (r = 0.618, p < 0.001). CONCLUSION: SWE is a feasible non-invasive technique for the assessment of liver fibrosis that can provide reliable results in the vast majority of people with class 3 obesity. SWE can be used to support the detection of significant fibrosis in addition to blood tests, thus limiting the need for liver biopsy only among those with suspected significant fibrosis