Magnetic resonance imaging in the assessment of metacarpophalangeal joint disease in early psoriatic and rheumatoid arthritis

Objectives: The aim of this study was to determine whether magnetic resonance imaging (MRI)-related entheseal changes including osteitis and extracapsular oedema could be used to differentiate between metacarpophalangeal (MCP) joint involvement in rheumatoid arthritis (RA) and psoriatic arthritis (PsA). Methods: Twenty patients (10 each with early RA and PsA) had dynamic contrast-enhanced MRI (DCE-MRI) of swollen MCP joints. Synovitis and tenosynovitis was calculated using quantitative analysis including the degree and kinetics of enhancement of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA). Periarticular bone erosion and bone oedema were scored using the Outcome Measures in Rheumatology Clinical Trials (OMERACT) proposals. Entheseal-related features including extracapsular soft tissue enhancement or regions of diffuse bone oedema were also evaluated. Results: MRI was not able to differentiate at the group level between both cohorts on the basis of entheseal-related disease but a subgroup of PsA patients had diffuse extracapsular enhancement (30%) or diffuse bone oedema (20%). The RA patient group had a greater degree of MCP synovitis (p0.0001) and tenosynovitis than PsA patients (p0.0001). There were no significant differences in either the total number of erosions (p=0.315) or the presence of periarticular bone oedema (p=0.105) between the groups. Conclusion: Although conventional MRI shows evidence of an enthesitis-associated pathology in the MCP joints in PsA, this is not sufficiently common to be of diagnostic utility.