Purpose: Shear wave elastography (SWE) has been validated in chronic hepatitis C and B; however, limited data are available in non-alcoholic fatty liver disease (NAFLD). This study aimed to evaluate the accuracy of SWE and FIB4 index for the diagnosis of fibrosis in a cohort of consecutive patients with biopsy-proven NAFLD, and to evaluate the effects of other histologic parameters on SWE measurement.
Methods: Written informed consent was obtained from all patients, and this study was approved by our internal review board and ethics committee. Seventy-one patients with histologically proven NAFLD (mean age 50.8 years ± 15.7) were examined. All patients underwent SWE (Aixplorer™; SuperSonic Imagine) and FIB4 index (based on age, aspartate aminotransferase and alanine aminotransferase levels, and platelet counts) measurements. SWE measurements were compared with the histologic features based on the NAFLD activity score and FIB4 index.
Results: The area under the ROC curve for the diagnosis of hepatic fibrosis stage 3 or higher was 0.821 (optimal cut-off value 13.1 kPa, sensitivity 62.5%, specificity 57.4%) for SWE and 0.822 (optimal cut-off value 1.41, sensitivity 71.9%, specificity 53.9%) for FIB4 index. The median liver stiffness values measured using SWE showed a stepwise increase with increasing hepatic fibrosis stage (P < 0.001), inflammation score (P = 0.018), and ballooning score (P < 0.001), and showed a stepwise decrease with increasing hepatic steatosis stage (P = 0.046).
Conclusions: SWE and FIB4 index are useful noninvasive tools for estimating the severity of fibrosis in NAFLD patients. However, the presence of severe steatosis may affect the liver stiffness measurement, resulting in underestimations of liver fibrosis.
Keywords: FIb4 index; NAFLD; Shear wave elastography; Ultrasound.