Sub-study to OSKIRA-4: A Phase IIB, Multi-Centre, Randomised, Double-Blind, Placebo-Controlled, Parallel Group Study of the Efficacy and Safety of Fostamatinib Disodium Monotherapy Compared with Placebo or Adalimumab Monotherapy in Patients with Active Rheumatoid Arthritis: Magnetic Resonance Imaging Sub-Study Date: 21 March 2011 Version: 1 Primary objective: Assess the efficacy of fostamatinib in reducing joint synovial disease activity as measured by: - Change from baseline to Week 6 (versus placebo) in OMERACT RAMRIS synovitis score.