1. Department of Pediatric Oncology, Hematology, and Clinical Immunology, Medical Faculty, Center for Child and Adolescent Health, University of Duesseldorf, Duesseldorf, Germany;
2. Clinic of Pediatric Hematology and Oncology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany;
3. Department of Pediatrics, University Medical Centre Schleswig-Holstein Campus Kiel, Kiel, Germany;
4. Pediatrics Department, University Hospital Rostock, Rostock, Germany;
5. University Hospital for Children and Adolescents, Johannes Wesling Klinikum Minden, Ruhr University Hospital, Bochum, Germany;
6. Department of Pediatrics, Evangelical Hospital, Bielefeld, Germany;
7. Pediatric Hematology and Oncology, Elisabeth-Hospital Oldenburg, Oldenburg, Germany;
8. Children's Hospital Karlsruhe, Karlsruhe, Germany;
9. Department of Pediatric Hematology and Oncology, University Hospital Bonn, Germany;
10. Department of Pediatric Oncology/Hematology, Children's Hospital Cologne, Cologne, Germany;
11. Cnopf'sche Kinderklinik, Nürnberg Children's Hospital, Nürnberg, Germany;
12. Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany;
13. Department of Diagnostic and Interventional Radiology, Medical Faculty, University of Duesseldorf, Duesseldorf, Germany