Bone erosions by MRI in first-degree relatives of patients with RA: an exploratory study

First-degree relatives (FDR) of patients with rheumatoid arthritis (RA) are at increased risk of RA diagnosis. Magnetic resonance imaging (MRI) has been proposed as a useful tool to detect subclinical synovitis and bone abnormalities as predictors of progression to RA. The presence of grade ≥ 2 bone erosions in RA MRI scoring system (RAMRIS) was reported to be RA-specific. We aim to describe the prevalence and characteristics of MRI findings in RA patients and FDR.

A cross-sectional and exploratory study of 60 individuals was performed in 38 RA patients and 22 FDR with hand arthralgia without clinical arthritis and positive rheumatoid factor or anticitrullinated protein antibodies. All patients underwent an MRI and were evaluated for synovitis, bone erosion, and bone marrow edema. We evaluated second to fifth metacarpophalangeal joints of the dominant hand according to RAMRIS.

Among the total population, eighteen (30%) subjects had grade ≥ 2 bone erosions, and 42 (70%) had at least one erosion of any grade. In patients with grade ≥ 2 bone erosions, 12 (31.6%) were from RA patients and 6 (27.2%) from FDR (p = 0.72). In patients with erosions of any grade, 26 (68.4%) were from RA patients and 15 (68.2%) were from FDR (p = 0.98).

A high prevalence of bone erosions was found in RA patients' FDR who had symptoms without clinical arthritis and positive serology. MRI might be helpful in this population for an early detection of RA-specific erosions. The prognosis and the treatment decisions in these subjects should be elucidated.

• First-degree relatives (FDR) of rheumatoid arthritis (RA) patients with positive serology and joint symptoms constitute a select subpopulation of individuals with an increased risk of developing RA. • Magnetic resonance imaging (MRI) of FDR shows a high prevalence of bone erosions of any grade, grade ≥ 2 erosions, and synovitis. • MRI might be helpful in FDR of RA patients to screen for the presence of RA-specific erosions or clinically undetectable synovitis.