RecruitingEarly Phase 1Drug trialPositron Emission Tomography (PET) Contrast Agent Kinetics and Safety: [18F]-FluoromannitolThis is a Phase 0 interventional, non-therapeutic study investigating the biodistribution and safety of \[18F\]-fluoromannitol as a radiotracer (a substance used to help detect disease or infection) in Positron Emission Tomography (PET) scans. The primary objective of this study is to generate safety data in healthy adult human volunteers. In the future, this tracer may help to determine if a medical problem is infectious in people who have Sickle Cell Disease, cancer or other conditions that impact the immune system, or with people who have joint implants. Primary Objective \- Generate safety data, biodistribution and perform human organ dosimetry for \[18F\]- fluoromannitol as a novel PET tracer. Participants will be recruited primarily from St. Jude Children's Research Hospital employees and SJLIFE participants, and from the broader Memphis community if needed.