Background The Outcome Measures in Rheumatology Study Group for MRI has developed a scoring system (PSAMRIS) to assess lesions and activity in metacarpophalangeal, proximal and distal interphalangeal joints in psoriatic arthritis (PsA) (1). Its performance is suitable to assess erosions and bone edema but inaccurate for others features. An alternative method to assess synovitis and bone edema is the quantification of enhancement in the synovial membrane and bone by extracting curves using a fast T1 –weighted sequence during intravenous administration of gadolinium contrast agent. This method, known as dynamic contrast enhanced MRI (DMR), can be useful to monitor the treatment effectiveness in patients with PsA (2).
Objectives To assess the utility of DMR as a reliable method to monitor the treatment response with DMARDS and anti-TNF alpha in patients with PsA.
Methods This is a prospective study performed in 15 patients with PsA according to CASPAR criteria, 5 females and 10 males. Eight of them were treated with anti-TNF (4 with adalimumab and 4 with etanercept) and seven with methotrexate. Monitoring consisted in a basal visit and at the third and sixth months after starting treatment, performing a MRI at each visit. At every visit the following variables were recorded: painful and swelling joint number (PJN and SJN), patient and doctor VAS, DAS 28, MASES, PASI, ESR, CRP and HAQ.
The MRI were performed using a high field 1-Tesla equipment in the most damaged hand, getting images T1 and STIR in the coronal plane and T1, T2 and T1-FAT SAT with contrast (gadolinium) in the axial plane. At each MRI a PSAMRIS determination was made. DMR involves the acquisition of sequential images in rapid succession every few seconds in the area with most active synovitis, during and after the intravenous administration of contrast agent. The parameter used from the enhancement curve was the early enhancement rate (RER).
Descriptive statistics was used. The correlations were done using Spearman's rank and changes from baseline to the follow-up visits were tested using the Friedman's test.
Results At baseline there was a significant correlation between RER and PSAMRIS (r=0,6; p=0.008) and between RER and CRP (r=0,7; p=0.004). At third month there was a significant correlation only between RER and PSAMRIS (r=0.8; p=0.013). A trend towards a positive correlation at baseline could be seen between RER and DAS28, PJN and SJN but without statistic signification and the same was observed for RER and PJN at third month. There was a significant decreased for PSAMRIS at sixth month (p=0.001) and a considerable decreased for RER but without signification.
Conclusions DMR is an useful sensitive imaging method to monitor activity in patients with PsA. Further studies with a larger number of patients and a longer following period are needed to establish its role in monitoring PsA.
Bøyesen P, et al. The OMERACT Psoriatic Arthritis Magnetic Resonance Imaging Score (PsAMRIS) is reliable and sensitive to change: results from an OMERACT workshop. J Rheumatology 2011; 38(9): 2034-8.
Cimmino MA, et al. Dynamic contrast-enhanced magnetic resonance imaging of articular and extraarticular synovial structures of the hands in patients with psoriatic arthritis. J Rheumatology 2012; 39(89):44-48.
Disclosure of Interest None declared
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