Patent ID: 6100780
Filing Date: 2000-08-08
Classification: G01R

Abstract:
An open magnetic resonance imaging magnet comprising:a) a first superconductive coil assembly including:(1) a toroidal-shaped first coil housing surrounding a first bore and having a longitudinal first axis; and(2) a generally annular-shaped first superconductive main coil coaxially aligned with said first axis, disposed within said first coil housing, and at least partially immersed in a cryogenic fluid;b) a generally-non-permanently-magnetized first ferromagnetic ring generally aligned with said first axis and spaced radially inward and radially apart from said first superconductive main coil;c) a second superconductive coil assembly including:(1) a generally toroidal-shaped second coil housing longitudinally spaced apart from said first coil housing, surrounding a second bore and having a longitudinal second axis coaxially aligned with said first axis; and(2) a annular-shaped second superconductive main coil coaxially aligned with said second axis, disposed within said second coil housing, and at least partially immersed in a cryogenic fluid; andd) a non-permanently-magnetized second ferromagnetic ring coaxially aligned with said second axis and spaced radially inward and radially apart from said second superconductive main coil, wherein said first and second ferromagnetic rings are spaced longitudinally inward and longitudinally apart from said first and second superconductive main coils, and wherein said first and second ferromagnetic rings are the only ferromagnetic rings of said magnet which are spaced radially and longitudinally inward and radially and longitudinally apart from said first and second superconductive main coils.