Magnetic resonance imaging system including active shield gradient coils

Abstract

Abstract A magnetic resonance imaging apparatus (1000 : 2000), comprises: an MR (magnetic resonance) imaging unit (600) having an imaging chamber to receive a subject (P), a superconducting coil unit (15) contained within an outer vessel (60) which is positioned around the imaging chamber (3), and including a superconducting coil assembly (17) for producing a uniform static magnetic field to be applied to the subject, and at least one heat shield tube (18) for thermally shielding the superconducting coil assembly (17). A gradient field coil assembly (50) is provided between the outer vessel (60) and imaging chamber (3) for producing a gradient magnetic field which is superimposed on the static magnetic field. An active shield gradient coil assembly (52) for producing a gradient shield field (H GS ) is disposed within the outer vessel (60) in such a manner that the active shield gradient coil assembly (52) is thermally coupled to the heat shield tube (18) and also magnetically coupled with a leakage field (H GL ) from the gradient magnetic field of the gradient field coil assembly (50), whereby the leakage field (H GL ) is magnetically cancelled by the gradient shield field (H GS ) and substantially no eddy current is produced in the heat shield tube (18).

Inventors

• 👤 Hiroshi Sugimoto

Bibliographic Details