Percutaneous liver biopsy remains the gold standard test to evaluate hepatic fat content, fibrosis and cirrhosis, but there is growing interest in the application of magnetic resonance imaging (MRI) techniques such as (1)H-Magnetic Resonance Spectroscopy ((1)H-MRS) as a non-invasive approach to quantify these characteristics. The ability to accurately quantify hepatic metabolites, such as intrahepatic lipid, has important implications for clinical evaluation and management of patients with liver related diseases and may obviate the need for liver biopsies in a number of clinical settings. The current proposal is designed to develop and validate hepatic (1)H-MRS capabilities at the NIH Clinical Center and to use this technique in a subsequent study to estimate the prevalence of hepatic steatosis among persons living with HIV/AIDS. In the present study we propose to complete MRI with (1)H-MRS in 70 adults who will be undergoing percutaneous liver biopsy in order to establish the ability of (1)H-MRS to accurately assess hepatic fat content compared to histopathological scoring.