Thomas Okell is the head of neurovascular imaging research within the physics group at the Oxford Centre for Functional MRI of the Brain (FMRIB). His research focuses on the development of non-invasive MRI methods to visualise the flow of blood through the arteries and the resulting perfusion of the brain tissue. These methods are being applied in a range of patient groups, including those with acute stroke and arteriovenous malformation. Thomas is also the director of physics education for the FMRIB graduate program. He trained as a medical physicist within the NHS before discovering the joys of arterial spin labelling during his PhD.