Background Patients with rheumatoid arthritis (RA) in clinical remission may still show progression of radiologic joint damage, possibly due to subclinical inflammation. In comparison to clinical examination, ultrasonography (US) and magnetic resonance imaging (MRI) are more sensitive tools for the detection of joint inflammation.
Objectives To compare US and MRI in the detection of synovitis in hand and wrist joints of patients with RA in clinical remission.
Methods In this cross-sectional study, we included 26 consecutive patients with RA (16 women and 10 men) who were in clinical remission according to the rheumatologist. This study was part of a larger study on assessment of synovitis in the hand and wrist in RA. The mean (SD) age was 50 (14) years, disease duration 74 (76) months and disease activity score assessing 28 joints (DAS28) 2.0 (0.66). All patients were treated with disease modifying antirheumatic drugs. The first to fifth metacarpophalangeal (MCP) joint of the right hand and wrist were examined with US and MRI. Joint inflammation was assessed with gray-scale (GS) US (grade 0-3) and power Doppler (PD) US (grade 0-3)1. We defined synovitis as a GS score > 1 and/or a PD score > 0. The scoring of synovitis on MRI (grade 0-3) was according the description in the OMERACT RAMRIS system2; for the wrist we took the average of the scores of 3 locations. We defined MRI synovitis as a score > 1.
Results Assessing MCP-1-5 and wrist on the right side, joint swelling was present clinically in 3 patients, with swelling of MCP-1 in 1 patient and MCP-2 in 2 patients. None of the other joints was clinically swollen. On US and MRI, synovitis of at least one of the joints was present in 7 (27%) respectively 12 (46%) patients. In contrast with MRI, no synovitis was seen of MCP-4 or MCP-5 on US. The reliability between both modalities was highest at MCP-2 and MCP-3 (kappa of 0.71 and 1.0, respectively).
Using the defined scoring system, synovitis was present in 9 of all 130 MCP joints and in 3 of 26 wrists on US. On MRI, synovitis was identified in 12 of 130 MCP joints and in 5 of 26 wrists. The agreement between synovitis on clinical examination and US, clinical examination and MRI, and US and MRI in the 156 assessed joints was 93%, 91%, and 90%, respectively. Spearman correlation coefficients between GS US and MRI, and PD US and MRI were 0.49 (p=0.01) and 0.33 (p=0.10), respectively.
Conclusions In this cohort of 26 RA patients clinically in remission, synovitis was present in 7 (27%) patients on US and in 12 (46%) on MRI. MRI seemed to be more sensitive in detecting synovitis, especially in MCP-4 and MCP-5. Further research is needed to evaluate the clinical relevance of this detection of subclinical synovitis on MRI and US in patients with RA in clinical remission.
Szkudlarek M, Court-Payen M, Jacobsen S, Klarlund M, Thomsen HS, Østergaard M: Interobserver agreement in ultrasonography of the finger and toe joints in rheumatoid arthritis. Arthritis Rheum 2003, 48:955-62
Østergaard M, Edmonds J, McQueen F, Peterfy C, Lassere M, Ejbjerg B, Bird P, Emery P, Genant H, Conaghan P: An introduction to the EULAR-OMERACT rheumatoid arthritis MRI reference image atlas. Ann Rheum Dis 2005, 64(Suppl 1):i3-i7
Disclosure of Interest None Declared