Nonalcoholic fatty liver disease (NAFLD) is currently the most common chronic liver disease worldwide. Although it has become one of the leading causes of cirrhosis and hepatocellular carcinoma in the Western world, the proportion of NAFLD patients developing these complications is rather small. Therefore, current guidelines recommend noninvasive tests for the initial assessment of NAFLD. Among the available non-invasive tests, transient elastography by FibroScan® (Echosens, Paris, France) is commonly used by hepatologists in Europe and Asia, and the machine has been introduced to the United States in 2013 with rapid adoption. Transient elastography measures liver stiffness and the controlled attenuation parameter simultaneously and can serve as a one-stop examination for both liver steatosis and fibrosis. Liver stiffness measurement also correlates with clinical outcomes and can be used to select patients for varices screening. Although obesity is a common reason for measurement failures, the development of the XL probe allows successful measurements in the majority of obese patients. This article reviews the performance and limitations of transient elastography in NAFLD and highlights its clinical applications. We also discuss the reliability criteria for transient elastography examination and factors associated with false-positive liver stiffness measurements.

Non-alcoholic fatty liver disease (NAFLD) affects around 30% of the global adult population and is an important cause of cirrhosis and hepatocellular carcinoma. Compared with other chronic liver diseases, NAFLD is mostly seen by primary care physicians and non-hepatologists. Though the absolute number is huge, only a small fraction of patients will eventually develop liver-related complications. Therefore, it is important to use noninvasive tests wisely and develop a care model that involves not only hepatologists but also other colleagues seeing patients with NAFLD. With this background, the American Gastroenterological Association commissioned a multidisciplinary group to provide guidance on a clinical care pathway for identifying patients with advanced liver fibrosis due to NAFLD. The 4 key steps of this pathway include ① identifying patients at risk at primary care or non-hepatology settings, ② initial assessment with history taking and physical examination, ③ screening for advanced fibrosis using simple fibrosis score, and ④ specific fibrosis test such as vibration controlled transient elastography in patients with indeterminate fibrosis scores. This article discusses the rationale of the recommendations and highlights areas needing further data and refinement.

Fatty Liver ; etiology ; therapy ; Humans

Inflammation is the key driver of liver fibrosis progression in non-alcoholic fatty liver disease (NAFLD). Unfortunately, it is often challenging to assess inflammation in NAFLD due to its dynamic nature and poor correlation with liver biochemical markers. Liver histology keeps its role as the standard tool, yet it is well-known for substantial sampling, intraobserver, and interobserver variability. Serum proinflammatory cytokines and apoptotic markers, namely cytokeratin-18, are well-studied with reasonable accuracy, whereas serum metabolomics and lipidomics have been adopted in some commercially available diagnostic models. Ultrasound and computed tomography imaging techniques are attractive due to their wide availability; yet their accuracies may not be comparable with magnetic resonance imaging-based tools. Machine learning and deep learning models, be they supervised or unsupervised learning, are promising tools to identify various subtypes of NAFLD, including those with dominating liver inflammation, contributing to sustainable care pathways for NAFLD.