Magnetic resonance imaging for the assessment of pathological hepatic findings in nonalcoholic fatty liver disease

The prevalence of nonalcoholic fatty liver disease (NAFLD) is expected to increase because of the current epidemics of obesity and diabetes, and NAFLD has become a major cause of chronic liver disease worldwide. Liver fibrosis is associated with poor long-term outcomes in patients with NAFLD. Additionally, increased mortality and liver-related complications are primarily seen in patients with nonalcoholic steatohepatitis (NASH); however, nonalcoholic fatty liver (NAFL) is believed to be benign and non-progressive. Therefore, distinguishing between NASH and NAFL is clinically important. Liver biopsy is the gold standard method for the staging of liver fibrosis and distinguishing between NASH and NAFL. Unfortunately, liver biopsy is an invasive and expensive procedure. Therefore, noninvasive methods, to replace biopsy, are urgently needed for the staging of liver fibrosis and diagnosing NASH. In this review, we discuss the recent studies on magnetic resonance imaging (MRI), including magnetic resonance elastography, proton density fat fraction measurement, and multiparametric MRI (mpMRI) that can be used in the assessment of NASH components such as liver fibrosis, steatosis, and liver injury including inflammation and ballooning.