1. Department of Pediatrics Akita University Graduate School of Medicine Akita Japan
2. Department of Neonatology Kanagawa Children's Medical Center Yokohama Kanagawa Japan
3. Neonatal Intensive Care Unit Department of Pediatrics Kyoto University Hospital Kyoto Japan
4. Division of Neonatology National Center for Child Health and Development Setagaya‐ku Tokyo Japan
5. Department of Radiology Kurashiki Central Hospital Kurashiki Okayama Japan
6. Department of Neonatal Medicine Osaka Women's and Children's Hospital Izumi Osaka Japan
7. Department of Neonatology Akita Red Cross Hospital Akita Japan