Yuika Sasatani1, Eiji Ojima2, Hiroaki Satoh3. 1. Division of Respiratory Medicine, Mito Medical Center, University of Tsukuba, Miya-machi 3-2-7, Mito, Ibaraki, 310-0015, Japan. 2. Division of Cardiology, Mito Medical Center, University of Tsukuba, Ibaraki, Japan. 3. Division of Respiratory Medicine, Mito Medical Center, University of Tsukuba, Miya-machi 3-2-7, Mito, Ibaraki, 310-0015, Japan. hirosato@md.tsukuba.ac.jp.