Magnetic resonance imaging apparatus and assembly process thereof

Magnetic resonance imaging apparatus comprising:

• a pair of a first magnet device and a second magnet device for generating a magnetostatic field, said pair of magnet devices being installed in face-to-face relation with each other across an examination space for accommodating an examinee;
• a gradient-field generating device;
• a high-frequency field generating device;
• and
• a yoke for combining said first and second magnetic devices to guide magnetic fluxes generated by said first and second magnetic devices to thereby form a closed magnetic circuit, wherein said yoke includes a first plate member fixed to a first magnet device, a second plate member fixed to a second magnet device and one or more support-post members interconnecting said first plate member and said second plate member, each of said first and second plate members and support-post members includes a plurality of segments formed in such a shape as to minimize leakage field strength from said first magnet device and said second magnet device;
• wherein each of said first and second plate members and said support-post members includes a plurality of segments of different shapes and said segments are combined in a pattern to match lines of magnetic induction generated by said first and second magnetic devices;
• and
• wherein said first and second plate members are formed by a larger number of segments at positions thereon where said first and second plate members are connected to said support-post members and also in vicinities of said positions than at the other positions.

Magnetic resonance imaging apparatus comprising:

• a pair of a first magnet device and a second magnet device for generating a magnetostatic field, said pair of magnet devices being installed in face-to-face relation with each other across an examination space for accommodating an examinee;
• a gradient-field generating device;
• a high-frequency field generating device;
• and
• a yoke for combining said first and second magnetic devices to guide magnetic fluxes generated by said first and second magnetic devices to thereby form a closed magnetic circuit, wherein said yoke includes a first plate member fixed to a first magnet device, a second plate member fixed to a second magnet device and one or more support-post members interconnecting said first plate member and said second plate member, each of said first and second plate members and support-post members includes a plurality of segments formed in such a shape as to minimize leakage field strength from said first magnet device and said second magnet device;
• wherein each of said first and second plate members and said support-post members includes a plurality of segments of different shapes and said segments are combined in a pattern to match lines of magnetic induction generated by said first and second magnetic devices;
• and
• wherein said first and second plate members have different numbers of segments at different positions based on a calculated magnetic flux distribution in said yoke.

Magnetic resonance imaging apparatus comprising:

• a pair of a first magnet device and a second magnet device for generating a magnetostatic field, said pair of magnet devices being installed in face-to-face relation with each other across an examination space for accommodating an examinee;
• a gradient-field generating device;
• a high-frequency field generating device;
• and
• a yoke for combining said first and second magnetic devices to guide magnetic fluxes generated by said first and second magnetic devices to thereby form a closed magnetic circuit, wherein said yoke includes a first plate member fixed to a first magnet device, a second plate member fixed to a second magnet device and one or more support-post members interconnecting said first plate member and said second plate member, each of said first and second plate members and support-post members includes a plurality of segments formed in such a shape as to minimize leakage field strength from said first magnet device and said second magnet device;
• wherein each of said first and second plate members and said support-post members includes a plurality of segments of different shapes and said segments are combined in a pattern to match lines of magnetic induction generated by said first and second magnetic devices;
• and
• wherein said first and second plate members have segments of shapes to match a calculated magnetic flux distribution.

Magnetic resonance imaging apparatus comprising:

• a pair of a first magnet device and a second magnet device for generating a magnetostatic field, said pair of magnet devices being installed in face-to-face relation with each other across an examination space for accommodating an examinee;
• a gradient-field generating device;
• a high-frequency field generating device;
• and
• a yoke for combining said first and second magnetic devices to guide magnetic fluxes generated by said first and second magnetic devices to thereby form a closed magnetic circuit, wherein said yoke includes a first plate member fixed to a first magnet device, a second plate member fixed to a second magnet device and one or more support-post members interconnecting said first plate member and said second plate member, each of said first and second plate members and support-post members includes a plurality of segments formed in such a shape as to minimize leakage field strength from said first magnet device and said second magnet device;
• wherein said first and second plate members and said support-post members are constructed by stacking in two or more layers segments formed by cutting steel plate.

Magnetic resonance imaging apparatus comprising:

• a pair of a first magnet device and a second magnet device for generating a magnetostatic field, said pair of magnet devices being installed in face-to-face relation with each other across an examination space for accommodating an examinee;
• a gradient-field generating device;
• a high-frequency field generating device;
• and
• a yoke for combining said first and second magnetic devices to guide magnetic fluxes generated by said first and second magnetic devices to thereby form a closed magnetic circuit, wherein said yoke includes a first plate member fixed to a first magnet device, a second plate member fixed to a second magnet device and one or more support-post members interconnecting said first plate member and said second plate member, each of said first and second plate members and support-post members includes a plurality of segments formed in such a shape as to minimize leakage field strength from said first magnet device and said second magnet device;
• wherein said shape to minimize said leakage field strength from said first and second magnet devices is a shape formed by varying a thickness of said segments according to a flux density of said leakage field generated by said first and second magnet devices.

Magnetic resonance imaging apparatus comprising:

• a pair of a first magnet device and a second magnet device for generating a magnetostatic field, said pair of magnet devices being installed in face-to-face relation with each other across an examination space for accommodating an examinee;
• a gradient-field generating device;
• a high-frequency field generating device;
• and
• a yoke for combining said first and second magnetic devices to guide magnetic fluxes generated by said first and second magnetic devices to thereby form a closed magnetic circuit, wherein said yoke includes a first plate member fixed to a first magnet device, a second plate member fixed to a second magnet device and one or more support-post members interconnecting said first plate member and said second plate member, each of said first and second plate members and support-post members includes a plurality of segments.