USG is sensitive in the detection of signs of inflammation and disease activity. USG assess changes in the severity of synovitis by measuring changes in synovial blood flow in multiple affected joints. Doppler ultrasonography quantifies the synovial inflammation and helpful in early diagnosis of RA. It is more sensitive to detect the bone erosions. Early changes such as hyperemia and synovial proliferation can be visualized by Doppler ultrasound. Color Doppler ultrasound detects subtle flow and quantifies the vascularity.