Brain scans can reveal new ways to diagnose and potentially treat psychiatric, psychological and neurological conditions. But why has the promise been so slow to turn into reality? Claudia Hammond is joined by Sophie Scott, Director of the Institute of Cognitive Neuroscience and also by neuroscientist Scott Marek of Washington University in St Louis. Plus one year on since fluoride toothpaste was added to the World Health Organisation's essential medicines list, Charles Mgbolu reports from Lagos about a market flooded with non-fluoridated toothpaste amid continued oral health concerns. And shocking results showing a global shortage of 43 million medical staff are discussed with study lead author Professor Rafael-Lozano. Plus studio guest family doctor Ann Robinson says there’s good news about new evidence for treating Crohn’s disease. Presenter: Claudia Hammond Producer: Erika Wright (Picture: A patient in MRI scanner with a nurse explaining the scan. Photo credit: ER Productions Limited/Getty Images.)