The Course of Bone Marrow Edema in Early Undifferentiated Arthritis and Rheumatoid Arthritis: A Longitudinal Magnetic Resonance Imaging Study at Bone Level.

OBJECTIVE

In patients with rheumatoid arthritis (RA), bone marrow edema (BME) scores are associated with development of erosions. However, little is known about the course and outcome of BME at bone level. We undertook this study to determine the association of BME and synovitis with the development of erosions in the same bone longitudinally.

METHODS

Using 1.5T magnetic resonance imaging at baseline and at 4- and 12-month follow-up, we studied 1,947 bones of the metacarpophalangeal, wrist, and metatarsophalangeal joints in 59 patients presenting with RA or undifferentiated arthritis. Scanning and scoring of BME, synovitis, and erosions were performed according to the Outcome Measures in Rheumatology Rheumatoid Arthritis Magnetic Resonance Imaging Scoring system. We evaluated the relationship of the course of BME and synovitis with erosive progression at bone level during 1 year.

RESULTS

Of the bones showing BME at baseline (n = 203), BME persisted in 56%, disappeared in 39%, and disappeared and then reappeared in 5%. Stratified analyses at baseline revealed that BME was associated with erosive progression both in the presence and in the absence of local synovitis, with odds ratios (ORs) of 7.5 (95% confidence interval [95% CI] 3.8-14.9) and 6.9 (95% CI 1.9-25.6), respectively. However, local synovitis was not associated with erosive progression in the presence or in the absence of BME (ORs of 2.0 [95% CI 0.6-7.0] and 1.9 [95% CI 0.8-4.1], respectively). In multivariable generalized estimating equation analyses, persistent BME was strongly associated with erosive progression (OR 60.5 [95% CI 16.8-218.1]) in contrast to persistent synovitis (OR 1.3 [95% CI 0.4-4.4]).

CONCLUSION

BME frequently persists during the first year. Persistent BME was strongly associated with erosive progression in the same bone, independently of local synovitis. No independent association was observed for persistent synovitis. These findings are relevant for comprehending the development of erosions in RA.