Patent ID: 6856223

Claim:
An open-type magnet device for MRI, comprising: a pair of an upper and a lower magnet assemblies which are arranged to oppose to each other so as to generate a uniform static magnetic field in a space region which covers a test portion of a subject, and each of which includes: a main superconductive coil for generating a uniform static magnetic field therebetween and an adjusting superconductive coil for adjusting magnetic field uniformity of the uniform static magnetic field; a cooling vessel containing the main superconductive coil and the adjusting superconductive coil for maintaining a superconductive state; and magnetic field adjusting means arranged at the uniform static magnetic field space side of the cooling vessel, so as to further adjust the magnetic field uniformity of the uniform static magnetic field space region; wherein the cooling vessel is a doughnut-shaped cooling vessel having a through hole in a center portion thereof and the magnetic field adjusting means is arranged at a predetermined position of the through hole; and the magnetic field adjusting means is also arranged to the side of the uniform static magnetic field space and outside the through hole.