Detecting scarred heart muscle is important to diagnose and treat of a wide variety of heart conditions. Magnetic resonance imaging (MRI) can assess scarred heart muscle but it is time consuming, contraindicated for some patients and not tolerated by others. Computed tomography (CT) imaging has the potential to provide a rapid comprehensive assessment of the heart. We plan to assess CT imaging of the blood vessels and heart muscle in 40 patients who have previously undergone MRI of their heart. Using a state of the art CT scanner we will develop a new low radiation dose protocol to identify scarred heart muscle. We will use and develop new software techniques to analyse these images and we will assess the diagnostic accuracy compared to MRI. This will enable us to develop a new way to identify and measure scarred heart muscle that will benefit patients with heart disease.