1. Contraindication for MRI scanning (as assessed by local MRI safety questionnaire), which includes, but is not limited to: presence of non-MRI compatible artificial heart valves, hydrocephalus shunts, intracranial aneurysm clips, joint replacements or metal implants, pacemakers or other cardiac rhythm management devices, claustrophobia, history of metal in the eye, presence of shrapnel from a war injury, callipers or braces, dentures, dental plates or hearing aids that include metal and cannot be removed, history of epilepsy or black-outs, ear implants, piercings cannot be removed, intrauterine contraceptive device or coil.