Intra-individual assessment of inflammatory severity and cartilage composition of finger joints in rheumatoid arthritis.

OBJECTIVE: To intra-individually assess the association of inflammation severity and cartilage composition measured by RAMRIS synovitis sub-score and delayed gadolinium-enhanced magnetic resonance imaging of the cartilage (dGEMRIC) of metacarpophalangeal (MCP) joints in patients with rheumatoid arthritis (RA).

METHODS: Forty-three patients with RA according to ACR/EULAR classification criteria (age 52.9 ± 14.5 years, range, 18-77 years) were included in this study. All study participants received 3-T MRI scans of the metacarpophalangeal joints of the second and third finger (MCP 2 and 3). The severity of synovitis was scored according to the RAMRIS synovitis sub-score by two readers in consensus. In the cases with identical synovitis sub-scores, two radiologists decided in consensus on the joint with more severe synovitis. Cartilage composition was assessed with dGEMRIC. To test the association of inflammation severity and cartilage damage and in order to eliminate inter-patient confounders, each patient's MCP 2 and 3 were dichotomized into the joint with more severe synovitis versus the joint with less severe synovitis for a paired Wilcoxon test of dGEMRIC value.

RESULTS: There was a significant difference of dGEMRIC value (median of difference: 47.12, CI [16.6; 62.76]) between the dichotomized MCPs (p = 0.0001). There was a significant correlation between dGEMRIC value and RAMRIS synovitis grading of the joint with more severe synovitis (r = 0.5; p < 0.05) and the joint with less severe synovitis (r = 0.33; p < 0.05).

CONCLUSIONS: Our data concur with the concept that synovitis severity is associated with cartilage damage. The local inflammatory status on a joint level correlated significantly with the extent of cartilage degradation in biochemical MRI.