1. Department of Neuroinflammation, MS NMR Research Unit, Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
2. Medical Statistics Unit, London School of Hygiene and Tropical Medicine, Kepple Street, London, WC1E 7HT, UK
3. Department of Headache, Brain Injury and Rehabilitation, MS NMR Research Unit, Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK