From the Department of Radiology, Kawasaki Medical School, Kurashiki City, Okayama, Japan.

Conflicts of interest and sources of funding: none declared.

Correspondence to: Yoshihiko Fukukura, MD, PhD, Department of Radiology, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama, 701-0192, Japan. E-mail: [email protected].