3. For the MRI imaging component, the following exclusions will apply; pacemaker, surgical clips within the head, certain inner ear implants, neuro-electrical stimulators or metal fragments within the eye or head or eGFR < 45 ml/min/1.73 m2. In patients with previous penetrating trauma to the eye, or patients at high risk of previous metal foreign body injury to the eye (e.g. welding), skull x-ray will be performed; these patients may be included in the absence of residual metal fragments on x-ray.