Tracking Peripheral Immune Cell Infiltration of the Brain in Central Inflammatory Disorders Using [Zr-89]Oxinate-4-labeled Leukocytes.

All study participants will undergo an investigational imaging study using autologous \[Zr-89\]-labeled leukocytes and brain PET/MRI. Participants will undergo a venous blood draw, and the leukocytes in the blood sample will be isolated for labeling using \[Zr-89\]oxine. The labeled leukocytes (7.4- 18.5 megabecquerel (MBq), 200-500 uCi) will be re-injected into the participant followed by brain PET/MRI at 24-48 hours after injection. Participants will be asked to have a second brain imaging study 3-6 days after this injection, but this second imaging study is optional.