Magnetic resonance imaging in rheumatoid arthritis clinical trials: emerging patterns based on recent experience.

OBJECTIVE: The current validated magnetic resonance imaging (MRI) scoring method for rheumatoid arthritis (RA) in clinical trials, RA MRI Score (RAMRIS), incorporates all metacarpophalangeal (MCP) and wrist joints except MCP-1. The experience with radiographic scoring, however, was that excluding certain bones in the wrist improved the discriminative power for changes over time. In this study, we pool MRI data from randomized controlled clinical trails (RCT) to determine which combination of MCP and wrist joints are most sensitive and discriminative for structural changes over time.
METHODS: MR images from 4 multicenter RCT, including 522 RA patients, were read by 2 radiologists, using the RAMRIS scoring system for erosion, osteitis, and synovitis. In one RCT, joint-space narrowing (JSN) was assessed cross-sectionally by one radiologist using a previously validated method. Baseline frequencies of erosion, JSN, osteitis, and synovitis of different bones and joints in the hand and wrist were compared. Intraclass correlation coefficients between readers were determined for each location. Finally, 7 different combinations of bone/joint locations were compared for their ability to discriminate subjects showing increases or decreases from baseline greater than or equal to smallest detectable changes (SDC) at Weeks 12 or 24.
RESULTS: Frequency of involvement and reliability for assessing change varied by location. As in earlier analyses, excluding certain wrist bones increased the percentage of subjects showing changes greater than or equal to SDC.
CONCLUSION: These findings suggest that excluding wrist bones that do not frequently or reliably demonstrate structural changes improves the discriminative power of the RAMRIS scoring system.