NeuroFLiPP: Parametric PET of Neuroinflammation in Fatty Liver Disease

Inclusion Criteria: * Participants \>=18 years age * Participants who have or have planned a liver biopsy as: * standard of care for fatty liver disease with risk factors for metabolic dysfunction-associated steatohepatitis (MASH), or * as part of another Clinical Trials study for MASH, or * standard of care prior to undergoing bariatric surgery * Liver biopsy needs to be within 6 months of planned study-related imaging * Ability to provide informed consent. Exclusion Criteria: * History of alcohol abuse, chronic hepatitis B or C, or other chronic liver disease other than non-alcoholic fatty liver disease. * Uncontrolled claustrophobia * Body weight \>225 kg due to limitations of the scanner bed * Pregnant or breast-feeding (due to risks of ionizing radiation; urine pregnancy test will be administered prior to start of each PET/CT session for all participants between 18 to 60 years old who are able to get pregnant, unless documented hysterectomy is available) * Concurrent or prior enrollment in a separate research study involving a PET scan performed within the last 12 months for research purposes only. * Prisoners * Any comorbidity that, in the opinion of the investigator, could compromise protocol objectives. * Pre-existing neurodegenerative disorders and dementia * Significant history of major skull concussion or repetitive head trauma * Currently on anticoagulant therapy * Metal implants (e.g., pacemaker) or claustrophobia that would preclude MRI scans