1. Hospices Civils de Lyon, 69006 Lyon, France
2. CREATIS Laboratory, INSA-Lyon, 69621 Villeurbanne, France
3. Imperial College London, London W12 0NN, UK
4. Imperial College Healthcare National Health Service Trust, London W12 0HS, UK
5. Department of Neuroradiology, Grande Ospedale Maggiore Niguarda, 20162 Milan, Italy