ARTHRITIS IN SYSTEMIC LUPUS ERYTHEMATOSUS: AN IMAGING POINT OF VIEW

Background. Arthritis in SLE is a frequent manifestation which can range from mild synovitis to severe erosive form. In rheumatoid arthritis, new musculoskeletal imaging tech- niques (US and MRI) have demonstrated high sensitivity in detecting early inflammatory and structural abnormalities. We hypothesized that a complete imaging evaluation integrating conventional radiography, US as well as MRI findings could allow a more accurate characterization of joint involvement in SLE permitting an earlier identification of patients at risk of longterm progression to deforming arthritis Aim. To study hand and wrist joints in a cohort of consecutive SLE patients and to compare US and MRI performances. Methods. 50 patients (45 female, mean age 39.8±14, mean disease duration 14.3±8) and 28 sex and age- matched healthy controls were enrolled. Assessment included a complete joint evaluation, autoantibodies determination, hand-wrist US with power Doppler (with a linear probe operating at 14 MHz) and MRI (with a 0.2 Tesla dedicated-extremity unit) without con- trast. Joint effusion (JE), bone erosion (BE) and edema (BED) were recorded and scored according to the RAMRIS scoring systems for RA. We decided not to include the gadolinium- containing contrast injection in our protocol because of the high prevalence of renal involvement in SLE patients (60%) in order to avoid possible gadolinum-related nephrotoxicity. Con- sidering the possible presence of BE also in healthy controls, we analyzed our controls to set-up an arbitrarily defined threshold of 5 to distinguish clinically significant erosive burden in our patients from aspecific bone lesions. Results. 20 (40%) SLE patients reported a history of clinically severe arthritis conditioning chronic pain and continuative ther- apy and 14 (28%) showed clinical signs of hand-wrist arthritis at enrolment. US examination revealed pathological findings in 23 patients (46%) showing hand and/or wrist arthritis in 12 and 11 respectively while tenosynovitis was recorded in 17 cases (34%). Synovial hypertrophy was detected in 27% of cases with positive power Doppler signal in 14%, and BE were found in 18% of cases. At MRI, pathological BE were detected in 63% of patients with arthritis (mainly at wrist) with con- comitant BED or effusion in 13%. The mean erosive burden resulted significantly higher in patients than in controls (8.95 vs 5.05. p<0.05). BED and JE revealed by MRI analysis sig- nificantly correlated with synovial hypertrophy at US. Conclusions. the integration of US and MRI findings, even without contrast injection, has a high sensitivity for the assess- ment of the broad spectrum of joint pathology in SLE with high reproducibility and low patients risk and discomfort. In fact, subclinical joint involvement as detected by US and MR appears frequent in SLE and can be also associated with severe synovial hypertrophy and bone erosion. Further studies to evaluate the role of these techniques in patients follow up are ongoing.