Nonalcoholic fatty liver disease (NAFLD) refers to a spectrum of liver abnormalities that involve a progression from steatosis to steatohepatitis, fibrosis, and cirrhosis. It is estimated that NAFLD occurs in about 20% of all adults in the United States. The prevalence of NAFLD increases with adiposity 1 and occurs in about 85% of extremely obese patients undergoing bariatric surgery. 2, 3 In addition, NAFLD is closely associated with the metabolic syndrome, and it has been proposed that NAFLD should be considered a component of the metabolic syndrome. 4–8 The presence of increased intrahepatic triglyceride (IHTG) content is associated with both hepatic and skeletal muscle insulin resistance, 3 and decreasing IHTG is associated with normalization of insulin sensitivity. 9

Reliable quantification of IHTG content is important in both clinical care and metabolic research. Histologic evaluation of liver tissue obtained by percutaneous biopsy is the current clinical gold standard for measuring IHTG content. Although this technique can also provide important information about other liver abnormalities, percutaneous liver biopsy can cause discomfort and serious medical complications, including bleeding, infection, and biliary leakage. 10 Ultrasound, computerized tomography, and magnetic resonance imaging (MRI) are noninvasive techniques that can be used to detect liver fat but do not provide a reliable quantification assessment of IHTG content. 11, 12