[1] INSERM, U1099, Rennes, France
[2] Univ Rennes 1, LTSI, F-35043 Rennes, France
[3] Univ Rennes 1, LTSI, F-35042 Rennes, France
[4] CHU Rennes, Dept Neurochirurg, F-35000 Rennes, France
[5] Univ Strasbourg, LSIIT, F-67412 Illkirch Graffenstaden, France
[6] UPMC, CRICM, CNRS, INSERM,UMR S975,UMR 7225, F-75013 Paris, France