To demonstrate MRI features of fatty infiltration and its effect on the detection and differential diagnosis of focal hepatic lesions. To illustrate the MRI characteristics of fat containing hepatic lesions. To provide an update on basic MR techniques for detection and characterization of focal hepatic lesions in the setting of diffuse fatty liver.

The prevalence of fatty liver disease in the general population is considerably high. As the diagnostic abilities of US and CT to detect and characterize focal hepatic lesion are severely impaired in the setting of fatty liver, MRI can offer advantages. Awareness of typical and atypical MR findings of both focal and diffuse fatty infiltration of the liver and its effect on the diagnosis of a hepatic mass is essential to avoid a misdiagnosis. We will describe two basic MR techniques, chemical shift imaging and fat saturation techniques, that can be used to detect and characterize fat containing lesions in the liver and focal liver lesion in the setting of fatty infiltration with the emphasis of diagnostic pitfalls. We will illustrate the MR features of various fat-containing liver lesions which include focal fatty infiltration, adenoma, lipoma, angiomyolipoma, and hepatocellular carcinoma with fatty metamorphosis.