Nonalcoholic fatty liver disease (NAFLD) is estimated to afflict approximately 1 billion
individuals worldwide. In a subset of NAFLD patients, who have the progressive form
of NAFLD termed nonalcoholic steatohepatitis (NASH), it can progress to advanced fibrosis,
cirrhosis, hepatocellular carcinoma, and liver-related morbidity and mortality. NASH
is typically characterized by a specific pattern on liver histology, including steatosis,
lobular inflammation, and ballooning with or without peri-sinusoidal fibrosis. Thus,
key issues in NAFLD patients are the differentiation of NASH from simple steatosis
and identification of advanced hepatic fibrosis. Until now, liver biopsy has been
the gold standard for identifying these 2 critical end points, but has well-known
limitations, including invasiveness; rare but potentially life-threatening complications;
poor acceptability; sampling variability; and cost. Furthermore, due to the epidemic
proportion of individuals with NAFLD worldwide, liver biopsy evaluation is impractical,
and noninvasive assessment for the diagnosis of NASH and fibrosis is needed. Although
much of the work remains to be done in establishing cost-effective strategies for
screening for NASH, advanced fibrosis, and cirrhosis, in this review, we summarize
the current state of the noninvasive assessment of liver disease in NAFLD, and we
provide an expert synthesis of how these noninvasive tools could be utilized in clinical
practice. Finally, we also list the key areas of research priorities in this area
to move forward clinical practice.