RecruitingPhase 2Drug trialA Pilot Study to Correlate 4-18F- Fluoro-1-naphthol 18F-4FN PET/CT Imaging With Chronic Graft Versus Host Disease ManifestationsTo study the safety and possible side effects of using the imaging agent 4-\[18F\]Fluoro-1-Naphthol (also called \[18F\]4FN) in PET/CT scans for participants with chronic GVHD.