1. Department of Urology, University Medical Center Goettingen, Goettingen, Germany
2. Department of Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany
3. Department of Urology and Pediatric Urology, Ortenau Hospital, Offenburg, Germany
4. Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut