Can Ultrasound Identify Synovitis?

Factors Influencing Concordance Between Clinical and Ultrasound Findings in Rheumatoid Arthritis

Le Boedec, Jousse-Joulin S, Ferlet JF, et al
J Rheumatol. 2013;40:244-252

Ultrasound for Synovitis

Emerging data suggest that ultrasound may be an important method to determine the degree of active synovitis in the joints of patients with rheumatoid arthritis.^[1] Furthermore, ultrasound may be more sensitive in identifying active synovitis than clinical joint examination.^[2] However, the rheumatologic community has not reached a consensus on when in the course of rheumatoid arthritis ultrasound is most helpful and what joints should be evaluated.^[3]

To address these issues, Le Boedec and colleagues performed simultaneous clinical joint examination and ultrasound to assess synovitis and evaluated the factors that were associated with concordance between these methods.

Study Summary

Seventy-six patients with active rheumatoid arthritis (defined as ≥ 6 swollen joints on clinical joint examination) were evaluated at baseline with simultaneous clinical joint examination and ultrasound; 66 of these patients were also evaluated 4 months after the institution of anti-tumor necrosis factor (TNF) therapy.

Synovitis on clinical joint examination was identified by the presence of swelling. (Tenderness was not evaluated.) Synovitis on ultrasound was identified by standard gray-scale (B-mode) images and power Doppler. The investigators evaluated 38 joints that included the proximal interphalangeal (PIP) joints, metacarpophalangeal (MCP) joints, wrists, elbows, shoulders, knees, and metatarsophalangeal (MTP) joints.

At the baseline visit, and before anti-TNF therapy, the investigators found that the concordance between clinical joint examination and ultrasound for synovitis varied across joints, with the lowest concordance being at the shoulders and MTP joints, where ultrasound was more sensitive for synovitis. Furthermore, low disease activity as measured by the Disease Activity Score 28-erythrocyte sedimentation rate (DAS28-ESR) was associated with higher concordance between synovitis by clinical joint examination and B-mode ultrasound. A shorter overall duration of rheumatoid arthritis was associated with a higher concordance between synovitis by clinical joint examination and by power Doppler ultrasound.

After anti-TNF therapy, only joint site was significantly associated with concordance between synovitis by clinical joint examination and by B-mode ultrasound, with the highest concordance seen in the MCP and PIP joints. In addition, factors that were associated with higher concordance between clinical joint examination and power Doppler ultrasound were joint site (highest in the MCP and PIP joints) and shorter duration of disease.

La Boedec and colleagues concluded that ultrasound may add the most useful information beyond clinical joint examination in the shoulders and MTP joints. They further concluded that the usefulness of B-mode ultrasound was reduced with low DAS28, and for power Doppler ultrasound when disease duration was short.