Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis: new trends and role of ultrasonography

Nonalcoholic fatty liver disease (NAFLD) is entering a new era in terms of diagnosis and conceptualization. The term NAFLD is considered to not reflect current knowledge. Metabolic dysfunction-associated fatty liver disease (MAFLD) has been suggested as a more appropriate overarching term by experts in this field. Regarding NAFLD progression, most patients die from non-liver-related diseases, even patients with advanced fibrosis. Liver biopsy is essential for the diagnosis of nonalcoholic steatohepatitis (NASH); it is the only procedure that reliably differentiates NAFLD from NASH. Recently, various noninvasive methods for diagnosing steatosis and fibrosis have been developed. Ultrasound attenuation measurements and proton density fat fraction with magnetic resonance imaging (MRI) have been developed as imaging tools for predicting steatosis. Fibrosis-4 index and NAFLD fibrosis score are complex scores for predicting fibrosis in patients with NAFLD. In addition, elastography based on ultrasound and MRI has been developed as an imaging tool for predicting fibrosis. There is a strong correlation between values from various real-time shear wave elastography devices and transient elastography, which is the gold standard for ultrasound-based measurements of liver stiffness. In conclusion, NAFLD is at a turning point in terms of its conceptualization, terminology, and diagnostics. It is now time to reconfirm the role of ultrasonography for the assessment of NAFLD.