1. Department of Otorhinolaryngology, Philipps–University, Marburg, Germany
2. Department of Otorhinolaryngology, Krankenhaus Holweide, Cologne, Germany
3. Department of Radiology, Philipps–University, Marburg, Germany
4. Institute of Medical Statistics and Epidemiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany