1. Department of Spine Surgery, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
2. Department of Neurosurgery, IRCCS Istituto delle Scienze Neurologiche Bologna, Bellaria Hospital, 40139 Bologna, Italy
3. Diagnostic and Interventional Radiology Unit, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy