Ultrasound evaluation of synovitis in RA: Correlation with clinical disease activity and sensitivity to change in an observational cohort study. - Zufferey, Pascal; Brulhart, Laure; Tamborrini, Giorgio; Finckh, Axel; Scherer, Almut; Moller, Burkhard; Ziswiler, Hans-Rudolf (Joint Bone Spine, 2014)