Background: There is an increased risk of metabolic-associated fatty liver disease (MAFLD) in individuals with class 3 obesity. There are no ideal non-invasive tests to assess liver fibrosis severity in this population where body habitus often makes imaging technically challenging. This study aimed to explore applicability and diagnostic performance of two-dimensional shear wave elastography (2D-SWE) in individuals with class 3 obesity.
Methods: This was a cross-sectional study conducted in a publicly funded multidisciplinary weight management program in Sydney, and included patients ≥18 years, BMI ≥40 kg/m2 and ≥1 weight-related medical comorbidity. 2D-SWE was performed using the ElastQ Imaging (EQI) procedure with the Phillips EPIQ Elite series, and an EQI Median value ≥6.43 kPa was considered significant fibrosis. Fibrosis-4 (FIB-4) index score, AST to Platelet Ratio Index (APRI) score, NAFLD fibrosis score (NFS), and circulating Fibroblast Activation Protein (cFAP) score were calculated from fasting blood samples.
Results: Participants (n=116; 67% female; 68% Caucasians) were aged 47.2±12.9 years, mean weight 153.6±33.4 kg and BMI 54.5±11.0 kg/m2. EQI Median values were obtained for 97% of the 2D-SWE scans. EQI Median had a moderate positive correlation with FIB-4 index score (r=0.438; p<0.001) and APRI (r=0.388; p<0.001), and a low positive correlation with NFS (r=0.210; p=0.036) and cFAP score (r=0.226; p=0.020). All the liver fibrosis scores had a low to moderate positive correlation with each other. Half (11/22 referred) of the participants underwent liver biopsy, and 2D-SWE had 72.7% accuracy (sensitivity:71.4%; specificity:75%).
Conclusions: 2D-SWE is a feasible non-invasive test to assess liver fibrosis among people with class 3 obesity. Further research is needed to assess whether 2D-SWE can be used to reliably detect significant fibrosis, likely in addition to risk scores calculated using blood tests, potentially limiting the need for an invasive liver biopsy.