1. Department of Radiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
2. Department of Diagnostic Pathology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
3. Department of Diagnostic Imaging, The Cancer Institute Hospital Japanese Foundation for Cancer Research, Tokyo, Japan.
4. Department of Obstetrics and Gynecology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.