Glucose uptake into the brain is reduced in patients with dementia and it is an important measurement to understand disease mechanisms and monitor progression. Brain imaging with 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) provides a gold-standard measurement of glucose uptake but requires invasive arterial blood sampling if quantitation is required. This is a feasibility study to optimise and validate a non-invasive magnetic resonance imaging (MRI) scan, called glucose-enhanced MRI (GE-MRI), to measure glucose uptake by the brain.