Bone edema scored on magnetic resonance imaging scans of the dominant carpus at presentation predicts radiographic joint damage of the hands and feet six years later in patients with rheumatoid arthritis.

OBJECTIVE

Magnetic resonance imaging (MRI) is capable of revealing synovitis and tendinitis in early rheumatoid arthritis (RA), as well as bone edema and erosion. These features are visible before radiographic joint damage occurs. We sought to examine whether MRI of one body region (the wrist) can be used to predict whole-body radiography scores reflecting joint damage at 6 years.

METHODS

We conducted a 6-year prospective study of a cohort of patients who fulfilled the criteria for RA at presentation, using clinical parameters, radiographs, and MRI scans of the dominant wrist. Of the 42 patients enrolled at baseline, full MRI, radiographic, and clinical data were available for 31 at 6-year followup. MRI scans were scored by 2 radiologists, using a validated scoring system. Radiographs of the hands and feet were graded using the modified Sharp scoring method. MRI and radiography scores obtained at baseline and 6 years were compared, and baseline MRI scores were examined for their ability to predict radiographic outcome at 6 years.

RESULTS

At 6 years, the total Sharp score correlated significantly with the total MRI score and the MRI erosion score (r = 0.81, P < 0.0001 and r = 0.79, P < 0.0001, respectively). The 6-year Sharp score also correlated with the baseline total MRI and MRI erosion scores (r = 0.56, P < 0.0001 and r = 0.33, P = 0.03, respectively). MRI synovitis and bone edema scores remained constant for the group as a whole over 6 years, but bone erosion scores progressed (P = 0.0001), consistent with radiographic deterioration. Erosions on 6-year MRI scans were frequently preceded by MRI bone edema at baseline (odds ratio 6.5, 95% confidence interval 2.78-18.1). Regression models indicated that the baseline MRI bone edema score was predictive of the 6-year total Sharp score (P = 0.01), as was the C-reactive protein (CRP) level (P = 0.0002). Neither shared epitope status nor swollen or tender joint counts predicted radiographic outcome in this cohort. A model incorporating baseline MRI scores for erosion, bone edema, synovitis, and tendinitis plus the CRP level and the erythrocyte sedimentation rate explained 59% of the variance in the 6-year total Sharp score (R(2) = 0.59, adjusted R(2) = 0.44).

CONCLUSION

MRI scans performed at the first presentation of RA can be used to help predict future radiographic damage, allowing disease-modifying therapy to be targeted to patients with aggressive disease.