PROBLEM TO BE SOLVED: To provide a vertical type MRI device using a yoke axially-asymmetric with respect to a vertical axis passing through the center of an imaging region that is capable of reducing an axially-asymmetric component in the magnetization distribution of a gradient magnetic field reinforcement member, and acquiring an excellent image without reducing an effect of the gradient magnetic field reinforcement member for reinforcing a gradient magnetic field by a gradient magnetic field coil.SOLUTION: An MRI device includes a magnetic field generation source for generating a magnetic field in an imaging region 9, a magnetic pole 4U, a toric ferromagnetic member fixed to the magnetic pole, and a gradient magnetic field coil, and has a pair of magnetic structures with the imaging region 9 between them, and an axially-asymmetric yoke 3 for connecting and supporting the pair of the magnetic structures. In each of the pair of the magnetic structures, the MRI device has a gradient magnetic field reinforcement material 11U disposed on the inner peripheral side of the toric ferromagnetic member, and between the gradient magnetic field coil and the magnetic pole, and a demagnetization coefficient adjustment part 12U disposed between the gradient magnetic field reinforcement material and the magnetic pole.COPYRIGHT: (C)2016,JPO&INPIT【課題】撮像領域の中心を通る鉛直軸に対して非軸対称なヨークを用いた垂直型MRI装置において、傾斜磁場コイルによる傾斜磁場を補強するための傾斜磁場補強部材の効果を低減することなく、傾斜磁場補強部材の磁化分布の非軸対称成分を軽減し、良好な画像を取得出来るMRI装置を提供する。【解決手段】MRI装置は、撮像領域9に磁場を生成する磁場発生源と、磁極4Uと、前記磁極に固定される円環状の強磁性体部材と、傾斜磁場コイルと、を含み、前記撮像領域9を間に有する一対の磁石構造物と、前記一対の磁石構造物を連結支持する非軸対称型のヨーク3と、を備え、前記一対の磁石構造物のそれぞれにおいて、前記円環状の強磁性体部材の内周側であって、かつ前記傾斜磁場コイルと前記磁極との間に配置される傾斜磁場補強材11Uと、前記傾斜磁場補強部材と前記磁極との間に設けられる反磁場係数調整部12Uと、を有する。【選択図】図3
