1. Sir Peter Mansfield Imaging Centre, Division for Respiratory Medicine, School of Medicine, University of Nottingham, Nottingham NG7 2RD, UK
2. Respiratory Pharmacology, Pharmacology and Toxicology, Faculty of Medicine, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
3. City Hospital Nottingham, Nottingham Respiratory Research Unit, Nottingham NG5 1PB, UK