Objective: To evaluate and compare sequential ultrasound exams (US) with power-Doppler (PD) to radiography for the detection of synovitis and erosions in patients with early RA. Methods: Radiographs and US with PD of the hands and feet were performed at baseline and 6± 2 months afterwards in 21 early RA patients. Their mean (range) age was 42.6 (21-81) years and the female/male ratio was 4:3; mean disease duration was 9 (1-28) months. Joints assessed were bilateral 2nd and 5th MCPs, 5th MTPs and the most swollen PIP in each hand, for a total of eight joints per patient. Radiographs (PA, lateral and pronated oblique) were read for erosions using the method of Sharp/ van der Heijde. On US, erosions were defined as cortical defects greater than 2 mm in diameter with an irregular floor. Synovitis was rated as +1 (increase in joint fluid without synovial hyperemia), +2 (mild blood flow), +3 (moderate blood flow), and +4 (severe blood flow). Two blinded trained assessors read all images. Results: US detected 15 erosions in 10 patients at baseline and 31 erosions in 12 patients on follow-up; radiographs could detect only one erosion at baseline and five erosions in three patients on follow-up. PD detected synovitis in all patients at baseline and on follow-up. Of the joints found to have synovitis, 64% were identified as such at baseline and 38% on follow-up. Conclusions: Sequential US can determine disease progression in patients with early RA. Such data may allow the clinician to treat RA patients earlier in the hope of preventing joint damage. © ISS 2006.