Magnetic resonance imaging (MRI) is a sensitive method to detect inflammation in rheumatoid arthritis (RA), visualizing synovitis, bone marrow edema, and tenosynovitis. The prevalence of MRI-detected tenosynovitis and its diagnostic value in early arthritis are unclear. This study was undertaken to identify the frequency of MRI-detectable tenosynovitis at the metacarpophalangeal (MCP) and wrist joints in early arthritis and the association of these with RA and the severity of RA.
A total of 178 patients with early arthritis underwent unilateral 1.5T extremity MRI at baseline. The MCP and wrist joints were scored using the Rheumatoid Arthritis Magnetic Resonance Imaging Scoring system and Haavardsholm's tenosynovitis score. Sixty-nine patients fulfilled the American College of Rheumatology/European League Against Rheumatism 2010 classification criteria for RA during the first year and were compared with the non-RA patients. Among the RA patients, comparisons were made with regard to anti-citrullinated protein antibody (ACPA) positivity and radiographic progression during year 1.
Of all patients, 65% had MRI-detected tenosynovitis. RA patients had tenosynovitis more often than non-RA patients (75% versus 59%; P = 0.023). The flexor tendons at MCP5 and the extensor tendons at MCP2 and MCP4 and in extensor compartment I of the wrist were more frequently affected in RA patients than in other patients (odds ratios 2.8 [95% confidence interval (95% CI) 1.2-7.0], 9.1 [95% CI 1.9-42.8], 14.2 [95% CI 1.7-115.9], and 4.0 [95% CI 1.4-11.1], respectively). These associations were independent of local MRI synovitis. Specificities were all ≥82%. Within the group of RA patients, tenosynovitis scores were not associated with ACPA positivity or radiographic progression.
MRI-detected tenosynovitis is commonly seen in early arthritis. The flexor tendons at MCP5, the extensor tendons at MCP2 and MCP4, and the first extensor compartment of the wrist are more often affected in RA, independent of local synovitis.