Noninvasive Imaging Methods to Determine Severity of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is now the most common form of liver disease in developed countries, with an estimated prevalence of 20%-30% and increasing to as high as 90% in diabetics. As the rates of NAFLD continue to rise in parallel with those of the obesity pandemic, it is increasingly important to differentiate those patients with the highest risk of progression to fibrosis and cirrhosis. In fact, those patients with nonalcoholic steatohepatitis (NASH) and fibrosis are at the greatest risk of progression to advanced disease, cirrhosis, and hepatocellular cancer and are more likely to develop liver-related mortality. Thus, it is critically important to distinguish between NASH and non-NASH NAFLD. Whereas liver biopsy remains the gold standard for staging of disease, complications of this procedure and other well-recognized limitations make it impractical for widespread use given the overall NAFLD disease burden. Noninvasive imaging modalities are increasingly being utilized to evaluate and stage NAFLD in patients with such a wide spectrum of disease. In this article, the role of these new and promising noninvasive imaging modalities to assess disease severity in NAFLD are reviewed.