Zr-89 Cimzia PET Imaging Rheumatoid Arthritis

Inclusion Criteria: 1. Age \> 18 years old. 2. Ability to read and understand written informed consent document. 3. Patients with clinical diagnosis of rheumatoid arthritis. Exclusion Criteria: 1. For patients planning to be imaged on PET (positron emission tomography) / MRI (magnetic resonance imaging) (PET/MR) scanner, exclusion criteria will include any contra-indication to MRI, including permanent pacemaker, implantable metallic device/ prosthetic, aneurysm clip, non-removable piercing, or severe claustrophobia. 2. Any medical condition that would compromise the imaging acquisition, in the opinion of the investigator. 3. Patients who have had a study involving radiation within one year of enrolling in this study. 4. Patients who are pregnant (female patients of childbearing age will be tested prior to injection of imaging agent - positive test will exclude from participating in the study). 5. Patients who are breastfeeding. 6. Patients who cannot confirm that they will use reliable contraceptive methods for 90 days. 7. Patients treated with TNF-alpha inhibitor therapy. 8. Females of child-bearing age (\<50 years old), until data from the dose-finding study has been reviewed by the UCSF Radiation Safety Committee and explicit written permission has been provided by the UCSF Radiation Safety Committee to open the window of potential female participants to ages 18 years and older.