Objectives MRI is recommended in the diagnostic process of rheumatoid arthritis (RA) to detect joint damage early. MRI-detected erosions are also present in symptom-free controls, especially at older age. It is unclear if RA-specific MRI-detected erosions can be distinguished from ‘physiological’ erosions in symptom-free individuals. This study compared MRI-detected erosions of patients with RA with healthy controls and with other arthritides.
Methods 589 newly presenting patients with early arthritis (238 RA, 351 other arthritides) and 193 symptom-free controls underwent contrast-enhanced 1.5T MRI of unilateral metacarpophalangeal and metatarsophalangeal (MTP) joints. Total erosion score (according to the Rheumatoid Arthritis MRI Scoring System), number, severity, location of erosions and simultaneous presence of MRI-detected inflammation (synovitis and/or bone marrow oedema) were compared; participants were categorised in three age groups (<40, 40–59, ≥60).
Results Patients with RA had statistically significant higher total erosion scores than controls but scores of individual persons largely overlapped. Grade ≥2 erosions and MTP5 erosions were specific for RA (specificity 98%–100% and 90%–98% for different age groups). MTP1 erosions were only specific if aged <40 (specificity 98%) and erosions with inflammation if aged <60 (specificity 91%–100%). ≥1 of the mentioned erosion characteristics were present in 29% of patients with RA. Comparing patients with RA with other arthritides revealed that grade ≥2 erosions and MTP5 erosions remained specific for RA (specificity ≥89%) as well as MTP1 erosions if aged <40 (specificity 93%), in contrast to erosions combined with inflammation (specificity 49%–85%).
Conclusions Total erosion scores of individual persons were largely overlapping. Erosion characteristics specific for RA were identified, but were infrequently present. Caution is needed not to overestimate the value of MRI erosions in the diagnostic process.
- rheumatoid arthritis
- magnetic resonance imaging
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Handling editor Tore K Kvien
Contributors DMB, WPN and AHMvdHvM contributed to the conception and study design. DMB analysed the data. DMB, WPN, HWvS, MR, RBML and AHMvdHvM contributed to interpretation of the data. DMB and AHMvdHvM wrote the first version of the manuscript and WPN, HWvS, MR and RBML revised it critically. DMB, WPN, HWvS, MR, RBML and AHMvdHvM read and approved the final manuscript.
Funding This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (Starting Grant, agreement number 714312) and from the Netherlands Organization for Health Research and Development (Vidi Grant).
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study on patients with early arthritis and the study on healthy controls were both approved by the local medical ethics committee ‘Commissie Medische Ethiek’.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data available.
Presented at This paper is based on work that was previously presented at the 2017 ACR/ARHP Annual Meeting, 7 November 2017, San Diego, California, and was published as a conference abstract: DMB et al, Arthritis Rheumatol. 2017; 69 (suppl 10).