Imaging of hepatic steatosis.

Hepatic steatosis is a common finding encountered during cross-sectional imaging examinations. This article reviews the imaging findings of hepatic steatosis as revealed by sonography, computed tomography, magnetic resonance imaging, and magnetic resonance spectroscopy. Focal fatty sparing and focal hepatic steatosis are conditions that can create potential diagnostic challenges for the radiologist. The typical findings, distribution, and etiology of these focal processes are presented. In the setting of diffuse hepatic steatosis, hepatic mass lesions can be difficult to discern on both computed tomography and sonography, with reported decreased sensitivity and specificity of lesion detection. In such cases, magnetic resonance imaging may be the imaging procedure of choice for the detection and characterization of both hepatic steatosis and coexistent hepatic masses. Some hepatocellular neoplasms, particularly hepatic adenoma and well-differentiated hepatocellular carcinoma, can have intratumoral lipid. By demonstrating the lipid content of these masses, imaging can add specificity in characterizing them as hepatocellular in origin because nonhepatocellular neoplasms in general do not contain intracellular lipid.