Dynamic, contrast-enhanced magnetic resonance imaging (DCE-MRI), the quantification of enhancement within the synovial membrane and bone by extracting curves using fast T1-weighted sequences during intravenous administration of contrast agent, evaluates synovitis and bone marrow edema in psoriatic arthritis (PsA). In this pilot study, we looked at possible differences between joint synovitis and tenosynovitis in PsA as compared with rheumatoid arthritis (RA).
Seven patients with PsA and 10 with RA were studied. After DCE-MRI was performed on 3 axial slices of the wrist, the enhancement ratio was calculated on 6 different regions of interest (ROI) of the synovial membrane outlined by the operator: the wrist compartment, 3 extensor tendon compartments, and 2 flexor compartments. DCE-MRI results were quantitatively analyzed using the Dynamika software, a computer-aided semiautomated method.
In PsA, the area of the ROI outlined around the first and second extensor compartments was larger than in RA; the opposite was true for the extensor carpi ulnaris region. The volume of inflammation was significantly higher in RA than in PsA for all the extensor compartments except the second, and in the joint synovial membrane. The DCE-MRI indicators of the degree of inflammation were higher for PsA in the joint synovial membrane (p = 0.002 and p < 0.001, respectively). There was a significant correlation between volume of inflammation but not its degree and 28-joint Disease Activity Score at the level of the wrist joint (r = 0.6; p = 0.01).
DCE-MRI can reveal useful and potentially clinically important information on the characteristics of different types of arthritis.