High-frequency sonography enables excellent detection of early erosions and synovial proliferations. Power Doppler sonography (PDUS) allows for an improved characterization of articular and peritendinous augmented volume, because detection of hypervascularity correlates with inflammatory activity and further is helpful in differentiation from effusion and inactive pannus. The use of contrast media improves the sensitivity of vascularity detection, because they allow for a delineation of vessels at the microvascular level. This is of increased interest, as the development of new therapeutic options targeting the microvascular level calls for earlier diagnosis and optimal assessment of disease activity. Because of good availability, cost effectiveness, and patient acceptance, sonography facilitates early diagnosis of synovial proliferations and erosions as well as therapy follow-up.