The aim of this study is to assess if three different functional magnetic resonance imaging (MRI) techniques are able to predict which patients will derive benefit from anti-angiogenic therapy early in their treatment. The study will recruit patients with mRCC who are going to be treated with anti-angiogenic drugs. These patients will have an MRI scan before they commence treatment and then a further scan after one treatment cycle (4 weeks) in addition to their normal clinical follow-up. The sequences being evaluated (arterial spin labeling, diffusion-weighted imaging and dynamic contrast imaging) look at the blood supply to the cancer and it is expected that there will be different changes in this blood supply in patients who are benefiting from treatment compared to those who are not responding. Early knowledge of response will help doctors choose the most appropriate treatment option for each individual patient.