Imaging of hepatic steatosis

Hepatic steatosis is a common finding encountered during cross-sectional im aging examinations. This article reviews the imaging findings of hepatic st eatosis 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 chal lenges for the radiologist. The typical findings, distribution, and etiolog y of these focal processes are presented. In the setting of diffuse hepatic steatosis, hepatic mass lesions can be difficult to discern on both comput ed tomography and sonography, with reported decreased sensitivity and speci ficity of lesion detection. In such cases, magnetic resonance imaging may b e 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 hepatocellu lar carcinoma, can have intratumoral lipid. By demonstrating the lipid cont ent of these masses, imaging can add specificity in characterizing them as hepatocellular in origin because nonhepatocellular neoplasms in general do not contain intracellular lipid.