18F-NaF PET uptake will be measured at baseline, and 6 months to assess the early impact of the intervention on valvular calcification activity. PET images on their own are difficult to interpret as they do not tell you where the radiation is coming from. For this reason the PET needs to be performed alongside CT which gives us images of the aortic valve. By superimposing the two images we are able to identify where the 'PET signal' is originating from.