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• Low-grade (grade 1) MRI-detected synovitis, tenosynovitis, and osteitis occur frequently in healthy controls and at-risk individuals who do not develop rheumatoid arthritis (RA).
• Such low-grade inflammation is observed at anatomical sites commonly involved in RA, complicating interpretation of MRI findings.
• Inflammation prevalence increases with age across all cohorts.
• Moderate to severe inflammation (grades 2 and 3) are rare in healthy and at-risk non-progressing groups, supporting their higher specificity for RA diagnosis.
