1. Department of Radiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan
2. Department of Cardiology, Toho University Omori Hospital, 6-11-1 Omori-Nishi, Tokyo 143-8541, Japan
3. Philips Electronics Japan, 2-13-37 Konan, Minato-ku, Tokyo 108-8507, Japan
4. Department of Cardiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan