1. Department of Medical Engineering, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan (F.N., M.Y., K.M.); and First Department of Anatomy, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan (T.K., Y.M.)