To define the anatomic distribution of the earliest inflammatory and structural changes in individuals with anti-citrullinated protein antibody (ACPA+) positivity but no signs of arthritis.
ACPA+ individuals (N = 20) and healthy controls (N = 13) received simultaneous gadolinium-enhanced magnetic resonance imaging (MRI) and high-resolution peripheral quantitative computed tomography (HR-pQCT) of the hands. MRI sequences were scored for synovitis, osteitis, and bone erosions according to the RAMRIS method as well as for presence, localization, and extent of tenosynovitis. Bone erosions were validated by HR-pQCT scanning and related to the inflammatory changes found in the MRI.
Tenosynovitis was the most prevalent inflammatory pathology, affecting 80% of ACPA+ individuals but none of the controls. Tenosynovitis at two or more anatomical sites was associated with later development of RA. Synovitis (65%) and osteitis (35%) were present in ACPA+ individuals as well, but at a lower frequency than tenosynovitis. MRI bone erosions were found in 65% of the individuals and additionally confirmed by HR-pQCT. Presence of MRI osteitis was the inflammatory pathology most strongly associated with bone erosions.
Tenosynovitis is highly prevalent in ACPA+ individuals without arthritis and associated with later development of RA. Small erosions, often linked to osteitis, are also found in ACPA+ individuals without arthritis.