RecruitingPhase 2Drug trialDevelopment of FAPI PET as a Non-invasive Biomarker of Pulmonary FibrogenesisThe goal of this clinical trial is to gain more information about how fibroblast activation protein inhibitor (FAPI) binds to a certain type of cells in fibrotic lung tissue and how this information can be used to better diagnose and track fibrotic lung disease activity. Participants will undergo up to 4 PET/MRI scans using the FAPI radiotracer.