iii. Contrast uptake Post-contrast and perfusion images are already in clinical use in ERA. In this study, post-contrast mDixon images will be developed and validated. Patients will be injected with intravenous contrast and scanned after a fixed delay. Inflamed joints will be analysed on post-contrast images, which will be compared with pre-contrast images to determine contrast uptake. Inflamed joints will again be analysed using region-of-interest (ROI) analysis. Again, quantitative scores will be correlated with clinical data and STIR scores for biological validation.