Evaluation of the Precision and Sensitivity of Tilmanocept Uptake Value (TUV) on Tc 99m Tilmanocept Planar Imaging

Inclusion Criteria: ALL SUBJECTS: 1. The subject has provided written informed consent with HIPAA (Health Information Portability and Accountability Act) authorization before the initiation of any study-related procedures. 2. ARMS 1 and 2 (only): The subject has agreed to not engage in any diet, lifestyle, or medication changes until study completion. HEALTHY CONTROL SUBJECTS 3. The subject is between 18 and 80 years of age at the time of consent. 4. The subject is deemed to be clinically free of any inflammatory disease(s) and has not experienced joint pain for at least 28 days prior to the consent date. 5. The subject is not currently on anti-inflammatory drugs (including NSAIDs) and has not taken anti-inflammatories for at least 28 days prior to the consent date. 6. For all ongoing concomitant medications, the subject has maintained a stable dose for at least 28 days prior to the consent date. CLINICALLY DIAGNOSED ACTIVE RA SUBJECTS: 3\. The subject is at least 18 years of age and was ≥ 18 years of age at the time of RA diagnosis. 4\. The subject has moderate to severe RA as determined by the 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) Classification Criteria (score of ≥ 6/10). 5\. The subject has a 28-joint disease activity score (DAS28) of ≥ 3.2 (includes the Erythrocyte Sedimentation Rate \[ESR\] test and Visual Analog Scale \[VAS\]). 6\. Subjects receiving traditional DMARDs must have been on therapy for ≥ 90 days and at a stable dose for ≥ 30 days prior to the first imaging visit (Day 0). 7\. If the subject is receiving bDMARD or janus kinase (JAK) inhibitor therapy, they have been at a stable dose \> 180 days prior to the first imaging visit (Day 0). 8\. If the subject is receiving NSAIDs or oral corticosteroids, the dose has been stable for \> 28 days prior to first imaging visit (Day 1). The corticosteroid dose must be ≤ 10 mg/day of prednisone or an equivalent steroid dose. 9\. ARM 3 (only): The subject is receiving anti-rheumatic treatment and is a candidate for initiation of, or change to, a new anti-TNFα bDMARD treatment. Exclusion Criteria: 1. The subject is pregnant or lactating. 2. The subject size or weight is not compatible with imaging per the investigator. 3. The subject has had or is currently receiving radiation therapy or chemotherapy. 4. The subject has renal insufficiency as demonstrated by a glomerular filtration rate of \< 60 mL/min. 5. The subject has hepatic insufficiency as demonstrated by ALT (alanine aminotransferase \[SGPT\]) or AST (aspartate aminotransferase \[SGOT\]) greater than 3 times the upper limit of normal. 6. The subject has any severe, acute, or chronic medical conditions and/or psychiatric conditions and/or laboratory abnormalities that would impart, in the judgment of the investigator, excess risk associated with study participation or study drug administration that would deem the subject inappropriate for study participation. 7. The subject has a known allergy to or has had an adverse reaction to dextran exposure. 8. The subject has received an investigational product within 30 days prior to the Tc 99m tilmanocept administration. 9. The subject has received intra-articular corticosteroid injections ≤ 8 weeks prior to the first imaging visit (Day 0). 10. The subject has received any radiopharmaceutical within 7 days or 10 half-lives prior to the administration of Tc 99m tilmanocept.