1. Department of Urology, University of Heidelberg, Heidelberg, Germany
2. Departments of Urology, University of Bonn, Bonn, Germany
3. Department of Medical Biometry, University of Heidelberg, Heidelberg, Germany
4. Städtisches Klinikum Kassel GmbH, Kassel, Germany
5. Department of Diagnostic Radiology, University of Heidelberg, Heidelberg, Germany