As therapy for rheumatoid arthritis (RA) becomes more effective, more sensitive imaging methods are required to assess disease activity and joint damage. We compared magnetic resonance imaging (MRI), sonography, and radiography for assessment of disease activity for the detection of bony erosions.
Forty-six patients with newly diagnosed RA (onset within 2 years) received clinical and laboratory assessment followed by radiographs, sonography, and MRI of the right hand at baseline and at 6 months according to a standardized protocol. We determined the presence of edema, synovitis, effusions, tendon fluid, tendon thickening, and size in the same way by MRI and sonography. The intra- and interreader reliability of MRI and radiographs and predictors of MRI erosions at 6 month followup were also examined.
At baseline, 39 (85%), 14 (30%), and 17 (37%) patients had erosions identified on MRI, sonography, and radiography, respectively. Over time, the percentage of patients with erosions increased to 91% for MRI, 41% for sonography, and 48% for radiography. The absolute number of erosions increased from 177 to 239 erosions for MRI, from 30 to 43 for sonography, and from 38 to 73 for radiographs. The intra- and interreader reliability for the assessment of erosions and synovitis on MRI was acceptable (intrareader ICC of 0.60 and 0.90; interreader ICC of 0.77 and 0.89, respectively).
MRI appears to be the most sensitive modality for erosive disease compared with sonography and radiography. Sonography detected more joint and tendon sheath effusions than MRI in this study and therefore may have a role in the assessment of disease activity.