1 Division of diagnostic and interventional neuroradiology, Geneva university hospitals and medical school, 4, rue Gabrielle-Perret-Gentil, 1211 Geneva 14, Switzerland. Electronic address: karl-olof.lovblad@hcuge.ch.
2 Division of diagnostic and interventional neuroradiology, Geneva university hospitals and medical school, 4, rue Gabrielle-Perret-Gentil, 1211 Geneva 14, Switzerland.