1. Department of Respirology , Graduate School of Medicine, , 1-8-1 Inohana, Chuo-Ku, Chiba , Japan
2. Chiba University , Graduate School of Medicine, , 1-8-1 Inohana, Chuo-Ku, Chiba , Japan
3. Department of General Thoracic Surgery, Dokkyo Medical University , 880 Kitakobayashi, Mibu, Shimotsuga, Tochigi , Japan
4. Department of Diagnostic Pathology , Graduate School of Medicine, , 1-8-1 Inohana, Chuo-Ku, Chiba , Japan
5. Biostatistics Section , Clinical Research Center, , 1-8-1 Inohana, Chuo-Ku, Chiba , Japan
6. Chiba University Hospital , Clinical Research Center, , 1-8-1 Inohana, Chuo-Ku, Chiba , Japan