[1] Juntendo Univ, Sch Med, Dept Radiol, Bunkyo Ku, Tokyo 1138421, Japan
[2] Tokyo Womens Med Univ, Sch Med, Dept Radiol, Shinjuku Ku, Tokyo 1628666, Japan
[3] Okayama Univ, Grad Sch Med & Dent, Sch Med, Dept Radiol, Okayama, Okayama 7008558, Japan
[4] Tokyo Womens Med Univ, Dept Otolaryngol, Tokyo, Japan