1. Department of Oral and Maxillofacial Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
2. Department of Cardiothoracic Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
3. Haemoscan, Stavangerweg 23-23, 9723 JC Groningen, The Netherlands
4. Department of Biomedical Engineering (FB 40), W.J. Kolff Institute, University Medical Center Groningen, University of Groningen, P.O. Box 196, 9700 AD Groningen, The Netherlands