| 摘要 |
A magnetic resonance imaging apparatus (10) includes a couch (54) for supporting a region of interest of a subject (44) being examined in an examination region. In one form, a main magnet for generating a substantially uniform temporally constant main magnetic field through the examination region includes a stationary pole piece (24), a movable pole piece (22), a ferrous flux return path (26), and a magnetic flux generator that selectively generates magnetic flux that flows between the pole pieces (22, 24) through the examination region and through the ferrous flux return path (26) which connects the pole pieces (22, 24). The stationary pole piece (24) is arranged adjacent a first side of the examination region. The movable pole piece (22) is arranged to be selectively moved between a first position adjacent a second side of the examination region opposite the stationary pole piece (24) so that the stationary and movable pole pieces (24, 22) define the examination region therebetween, and a second position remote from the examination region. In other forms, the entire magnet is movable away from the examination region. <IMAGE> |
