Background MRI is a highly sensitive technique for revealing rheumatoid erosions. Studies from this cohort have revealed MR wrist erosions in 45% and XR erosions in 12% of early RA patients.1 It has been proposed that MR erosions progress to XR erosions during the course of RA but lesion-based evidence for this is scarce. We have used MR and XR data from this cohort to examine the predictive value of a baseline MR score and to track the fate of individual lesions over a 2 year period.
Methods An inception cohort of 42 early RA patients have been studied since symptom-onset. Clinical, MR (1.5 Tesla GE Signa Horizon scanner) and XR data were obtained at baseline and 1 year. MR scans of the dominant wrist and XRs of the same region were read independently by 2 radiologists and scored for erosions at 15 sites within the carpus. Further 2 year clinical and XR data was used to determine the ability of the baseline MRI score to predict XR erosions at 2 years. A lesion-based analysis was also performed to track individual lesions from MR at 0 and 1 year time-points to XR at 1 and 2 years.
Results The baseline MR erosion score was predictive of XR erosion score at 2 years (p = 0.008).
Patients with a total MR score (erosions, bone oedema, synovitis and tendonitis) > = 13 at baseline were significantly more likely to develop erosions on XR at 2 years (OR 13.4, 95% CI [2.65, 60.5], p = 0.002). Baseline wrist MRI has a sensitivity of 80%, a specificity of 76%, a positive predictive value (ppv) of 67% and a high negative predictive value (npv) of 86% for the prediction of wrist XR erosions at 2 years. A lesion-centred analysis, revealed that 84% of baseline MR erosions were still present at one year, increasing to 100% if complete concordance between radiologists was required. The number of MR erosion sites per patient increased from 2.1 (SD 2.7) to 5.0 (SD 4.6) (p < 0.0001) over the 1st year of disease. When MR erosion sites were tracked, 21% and 26% were observed on XR, 1 and 2 years later. A high baseline Ritchie score and ESR were predictive of progression of MR to XR erosions over 1 year (p = 0.01 and 0.03) but there was no association with the shared epitope. Progression of MR to XR erosions was not seen in those with transient polyarthritis.
Conclusion MRI scans of the wrist taken at first presentation of RA can be useful in predicting radiographic erosions. Thus, MRI may have a role in selection of patients for more or less aggressive management. Most MR lesions persist over the first year of disease but only 1 in 4 progress to XR erosions at the same sites, 1 year later. This may relate to healing, observer error or technical limitations of radiography at the wrist. Progression of MR to XR erosions is greatest in those with high baseline disease activity.
McQueen FM, Stewart N, Crabbe J, Robinson E, Yeoman S, Tan P, McLean L. Magnetic resonance imaging of the wrist in early rheumatoid arthritis reveals a high prevalence of erosions at four months after symptom-onset. Ann Rheum Dis. 1998;57:350–6