Ultrasound and structural changes in inflammatory arthritis: synovitis and tenosynovitis.

Accurate assessment of disease activity and joint damage in rheumatological diseases is important for monitoring treatment efficacy and predicting the disease outcome, and such assessment requires sensitive imaging tools. Conventional radiography is insensitive to soft tissue lesions and to early erosive bone lesions. Musculoskeletal ultrasonography has become an important diagnostic technique in rheumatological diseases, as it can detect both early inflammatory soft tissue lesions (e.g., synovitis, tenosynovitis, and bursitis) and early erosive bone lesions in arthritic joint diseases. Studies show good correlation in this regard between ultrasound and magnetic resonance imaging. Owing to good soft tissue contrast, ultrasound enables differentiation between exudative and proliferative synovial changes and may also direct further diagnostic and therapeutic procedures and color and power Doppler ultrasonography help to differentiate active from inactive joint processes. Specifically, the use of contrast agents increases the sensitivity for the detection of a thickened, hypervascular, and inflamed joint capsule and enables better quantification of inflammatory disease by estimating ultrasound signal intensity changes. At present, contrast-enhanced ultrasonography is of particular interest for clinical studies in monitoring the new anti-inflammatory drugs used to treat rheumatological diseases.