Marrow oedema is identified as a feature of many forms of inflammatory and mechanical arthritis, but has been most studied in inflammatory arthritides and particularly in rheumatoid arthritis. It was first reported as a feature of RA as far back as 1986. Studies have been undertaken both using human specimens and specimens from animal models, which suggest that marrow oedema seen on MRI in RA corresponds to areas of inflammation associated with invading pannus, lymphocytic aggregates and hypervascularity. There is also evidence that the marrow lesions seen on MRI in ankylosing spondylitis correspond to histopathological inflammatory change. Marrow oedema has been shown to be an important predictor of future joint damage in patients with rheumatoid arthritis. In addition to predicting bone destruction for erosion, marrow oedema is independently predictive of joint space loss and therefore cartilage destruction. It also correlates well with other measures of disease activity. We have applied dynamic contrast enhancement techniques to show that treatment with anti-TNF therapy brings about a reduction in contrast uptake in areas of marrow oedema in patients with RA. In the seronegative arthritides, marrow oedema in the spine in ankylosing spondylitis has been shown to be predictive of future changes and of response to treatment. Diffusionweighted imaging of marrow lesions in ankylosing spondylitis can also be used to show a treatment response, seen as a change in the apparent diffusion coefficient. Learning Objectives: 1. To become familiar with the imaging pattern of seronegative and rheumatoid arthritis distribution. 2. To understand the relationship between BME and early diagnosis of inflammatory disease. 3. To understand whether BME helps in patient management, diagnosis and follow-up.