1. Department of Thoracic Surgery, Hokkaido University Hospital, Sapporo 060-8648, Hokkaido, Japan
2. Division of Radiology, Department of Medical Technology, Hokkaido University Hospital, Sapporo 060-8648, Hokkaido, Japan
3. Department of Biomedical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA