1. Department of Pediatric Pulmonology, Sophia Children's Hospital/Erasmus Medical Centre Rotterdam, Rotterdam, The Netherlands
2. Department of Otolaryngology, Sophia Children's Hospital/Erasmus Medical Centre Rotterdam, Rotterdam, The Netherlands
3. Department of Pediatric Radiology, Sophia Children's Hospital/Erasmus Medical Centre Rotterdam, Rotterdam, The Netherlands
4. Materialise, Leuven, Belgium
5. Department of Pediatric Pulmonology, Sophia Children's Hospital/Erasmus Medical Centre Rotterdam, Rotterdam, The Netherlands; tiddens@alkg.azr.nl