Magnetic resonance imaging system with iron-assisted magnetic field gradient system
First Claim
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1. A magnetic resonance imaging apparatus comprising:
- a main magnet surrounding an examination region and generating a main magnetic field in the examination region, the main magnet including a plurality of spaced apart generally annular magnet segments surrounding an examination region; and
a magnetic field gradient system disposed outside of the main magnet, the magnetic field gradient system including;
a ferromagnetic yoke including a plurality of ferromagnetic flux distribution elements disposed between the spaced apart magnet segments, anda plurality of magnetic field gradient coils magnetically coupled with the ferromagnetic yoke and selectively producing magnetic flux in the ferromagnetic yoke, the magnetic flux in the ferromagnetic yoke producing selected magnetic field gradients in the examination region.
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Abstract
A magnetic resonance imaging apparatus includes a main magnet (20) that surrounds an examination region (18) and generates a main magnetic field in the examination region. A magnetic field gradient system (30) is disposed outside of the main magnet. The magnetic field gradient system includes a ferromagnetic yoke (32), and a plurality of magnetic field gradient coils (34) magnetically coupled with the ferromagnetic yoke and selectively producing magnetic flux in the ferromagnetic yoke. The magnetic flux in the ferromagnetic yoke produces selected magnetic field gradients in the examination region.
28 Citations
25 Claims
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1. A magnetic resonance imaging apparatus comprising:
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a main magnet surrounding an examination region and generating a main magnetic field in the examination region, the main magnet including a plurality of spaced apart generally annular magnet segments surrounding an examination region; and a magnetic field gradient system disposed outside of the main magnet, the magnetic field gradient system including; a ferromagnetic yoke including a plurality of ferromagnetic flux distribution elements disposed between the spaced apart magnet segments, and a plurality of magnetic field gradient coils magnetically coupled with the ferromagnetic yoke and selectively producing magnetic flux in the ferromagnetic yoke, the magnetic flux in the ferromagnetic yoke producing selected magnetic field gradients in the examination region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A magnetic resonance imaging apparatus comprising:
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a main magnet surrounding an examination region and generating a main magnetic field in the examination region; and a magnetic field gradient system disposed outside of the main magnet, the magnetic field gradient system including; a ferromagnetic yoke including a plurality of ferromagnetic flux distribution elements, a plurality of ferromagnetic cross bars magnetically coupled with the ferromagnetic flux distribution elements, and a plurality of magnetic field gradient coils magnetically coupled with the ferromagnetic yoke and selectively producing magnetic flux in the ferromagnetic yoke, the magnetic field gradient coils being wrapped around the ferromagnetic cross bars, the magnetic flux in the ferromagnetic yoke producing selected magnetic field gradients in the examination region. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A magnetic field gradient system comprising:
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a ferromagnetic yoke including a plurality of ferromagnetic flux distribution elements magnetically coupled by cross-bars; and a plurality of magnetic field gradient coils magnetically coupled with the ferromagnetic yoke and selectively producing magnetic flux in the ferromagnetic yoke, the magnetic flux in the ferromagnetic yoke producing selected magnetic field gradients in an examination region.
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23. A magnetic resonance imaging apparatus comprising:
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a main magnet including a plurality of generally annular magnet segments surrounding an examination region and generating a main magnetic field in the examination region; a magnetic field gradient system including a plurality of ferromagnetic flux distribution elements to generate selected magnetic field gradients in the examination region, the ferromagnetic flux distribution elements being disposed between the generally annular magnets; a vacuum jacket containing the main magnet and the magnetic field gradient system, the vacuum jacket having a wall defining a bore of the imaging apparatus, the examination region being disposed in the bore; a radio frequency coil disposed on a surface of the bore outside of the vacuum jacket; and a radio frequency screen disposed on a surface of the bore inside of the vacuum jacket. - View Dependent Claims (24, 25)
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Specification