Sandra Bracco1, Eugenio Bertelli2. 1. Unit of Interventional Neuroradiology, Azienda Ospedaliera Universitaria Senese (AOUS), University of Siena, Policlinico "Santa Maria Alle Scotte", Siena, Italy. 2. Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy. eugenio.bertelli@unisi.it.