Non-invasive evaluation of liver steatosis with imaging modalities: New techniques and applications

Abstract

In the world, nonalcoholic fatty liver disease (NAFLD) accounts for majority of diffuse hepatic diseases. Notably, substantial liver fat accumulation can trigger and accelerate hepatic fibrosis, thus contributing to disease progression. Moreover, the presence of NAFLD not only puts adverse influences for liver but is also associated with an increased risk of type 2 diabetes and cardiovascular diseases. Therefore, early detection and quantified measurement of hepatic fat content are of great importance. Liver biopsy is currently the most accurate method for the evaluation of hepatic steatosis. However, liver biopsy has several limitations, namely, its invasiveness, sampling error, high cost and moderate intraobserver and interobserver reproducibility. Recently, various quantitative imaging techniques have been developed for the diagnosis and quantified measurement of hepatic fat content, including ultrasound- or magnetic resonance-based methods. These quantitative imaging techniques can provide objective continuous metrics associated with liver fat content and be recorded for comparison when patients receive check-ups to evaluate changes in liver fat content, which is useful for longitudinal follow-up. In this review, we introduce several imaging techniques and describe their diagnostic performance for the diagnosis and quantified measurement of hepatic fat content.

Keywords: Non-alcoholic fatty liver disease; Hepatic steatosis; Imaging techniques; Quantitative evaluation; Ultrasound; Quantitative ultrasound

Core Tip: Accurate evaluation of the hepatic steatosis is important. The conventional gray scale ultrasound has the limitation of low diagnostic accuracy for mild hepatic steatosis and inability to make quantification evaluations. Quantification imaging techniques including ultrasound-based techniques and magnetic resonance imaging-based techniques can provide objective continuous numbers associated with liver fat content and past records can be found when patients receiving check-ups to evaluate change of liver fat content, which is useful for the longitudinal follow-up to monitor the impact of clinical interventions.