Hyperpolarized Pyruvate (13C) Magnetic Resonance Imaging In Patients With Fatty Liver Disease

PRIMARY OBJECTIVES: 1. Optimize scan parameters in order to maximize the signal-to-noise ratio of the HP 13C-pyruvate magnetic resonance imaging (MRI) in the liver. 2. Determine whether the level of lactate production (as measured by the lactate/pyruvate ratio) in NASH participants, participants with simple NAFL, and healthy volunteers. SECONDARY OBJECTIVES: 1. Develop data analysis methods to quantify HP C-13 pyruvate MRI data. 2. Further characterize the safety profile of HP C-13 pyruvate injections. EXPLORATORY OBJECTIVES: 1. Examine the impact of the dual liver blood supply on the vascular kinetics of observed hyperpolarized 13C metabolism. 2. Improve methods of quantification and motion correction for hyperpolarized 13C acquisition, incorporating perfusion information derived from 13C Urea OUTLINE: Part 1: (Imaging Optimization, N=50): Participants enrolled in Part 1 will predominantly be healthy volunteers. As the protocol optimization is completed, there is a possibility that testing in using data from participants with fatty liver disease may be performed. Participants in this part will be divided into two cohorts: * Cohort A: Participants will undergo MRI but no injection of hyperpolarized 13C. * Cohort B: Participants will receive one HP 13C injection. Participants in this cohort will have the option of undergoing repeated dose imaging studies of HP 13C-pyruvate or HP 13C-pyruvate+HP 13C-urea "copol", for up to a total of two injections per imaging visit. Part 2: (Pilot Study, N=30): Participants enrolled in Part 2 will receive the HP 13C-pyruvate or HP13C-pyruvate+HP13C-urea "copol" protocol that was optimized in Part 1 as well as standard liver MRI pulse sequences. Participants will be stratified into the following groups based on diagnosis: * Group 1 (n=10): Participants with a diagnosis of non-alcoholic fatty liver without steatohepatitis (NAFL) * Group 2 (n=10): Participants with a diagnosis of non-alcoholic steatohepatitis (NASH) * Group 3 (n=10): Participants with no known liver disease (healthy volunteers) Participants will be followed for 2-4 days following imaging procedure.