1. Department of Neonatology, Children's Hospital, Kuopio University Hospital, Kuopio, Finland; Department of Pediatrics, Kuopio University Hospital, P.O. Box 1777, FIN-70211 Kuopio, Finland
2. Department of Neonatology, Children's Hospital, Kuopio University Hospital, Kuopio, Finland
3. Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland