1. Centre d′imagerie Médicale, 47 Boulevard du Pont Rouge, 15000 AURILLAC, France
2. Department of Radiology, Hôpital Raymond Poincaré, Assistance Publique-Hôpitaux de Paris, Université Paris Ile-de-France Ouest, 104 boulevard Raymond Poincaré, 92380 Garches, France
3. Department of Head and Neck and Interventional Radiology, Antoine Lacassagne Cancer Research Institute, 33, Avenue Valombrose, 06189 Nice cedex1, France
4. Department of Radiation Oncology, Antoine Lacassagne Cancer Research Institute, 33, Avenue Valombrose, 06189 Nice cedex1, France