MRI magnets
AssigneeOxford Magnet Technology Limited
InventorJonathan L. Allis
Life of this patent
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Abstract
An MRI magnet arrangement comprises, an annular electromagnet defined by a coil, an annular shim of magnetic material coaxially disposed within the coil, first permanent magnet means having a field, the direction of which is the same as the field of the coil, disposed coaxially within the said shim and second permanent magnet means disposed coaxially within the said first permanent magnet means, the field of which is arranged to be opposite in direction to the field produced by the said first permanent magnet means, the arrangement being such that the magnetic field produced in an imaging volume within the said second permanent magnet means is substantially homogeneous.
Claims9
An MRI magnet arrangement comprises, an annular electromagnet defined by a coil having a field, an annular shim of magnetic material coaxially disposed within the coil, first permanent magnet means for producing a field, the direction of which is aligned with the field of the coil, disposed coaxially with the annular shim of the magnetic material, second permanent magnet means providing an imaging volume and being disposed coaxially within said first permanent magnet means, for producing a field which is arranged to be opposite in direction to the field produced by said first permanent magnet means, the arrangement being such that the magnetic field produced in the imaging volume within said second permanent magnet means is substantially homogeneous.
A magnetic resonance imaging system including means for supporting a body to be scanned;
- MRI magnet means for generating a homogenous magnetic field;
- means for obtaining MRI signals from the body in the magnetic field;
- and means for generating an MRI image from the obtained MRI signals;
- wherein the improvement of said MRI magnet means comprises:
- an annular electromagnet defined by a coil having a field, an annular shim of magnetic material coaxially disposed within the coil, first permanent magnet means for producing a field, the direction of which is aligned with the field of the coil, disposed coaxially with the annular shim of the magnetic material, second permanent magnet means providing an imaging volume and being disposed coaxially within said first permanent magnet means, for producing a field which is arranged to be opposite in direction to the field produced by said first permanent magnet means, the arrangement being such that the magnetic field produced in the imaging volume within said second permanent magnet means is substantially homogenous.
Dependencies are inferred from the claim text.