Abstract: A method is presented for manufacturing laminate tile metal pole pieces for an MRI. Each laminate tile has a trapezoidal or annular sector shape. The trapezoidal shape allows the tiles to be attached side by side to form a multiple concentric annular array pole piece without using oddly shaped edge filler tiles needed to fill a circular pole piece with square tiles. The pole piece is made by placing a plurality of tiles into a mold and filling the mold with an adhesive substance to bind the plurality of tiles into a unitary tile body. The unitary tile body is then removed from the mold and attached to a pole piece base to form the pole piece. The mold cavity surface preferably has a non-uniform contour. The bottom surface of the unitary tile body forms a substantially inverse contour of the mold cavity surface contour.

Abstract: A laminate tile pole piece for an MRI, a method and a mold for manufacturing laminate tile metal pole pieces for an MRI. Each laminate tile has a trapezoidal or annular sector shape. The trapezoidal shape allows the tiles to be attached side by side to form a multiple concentric annular array pole piece without using oddly shaped edge filler tiles needed to fill a circular pole piece with square tiles. The pole piece is made by placing a plurality of tiles into a mold and filling the mold with an adhesive substance to bind the plurality of tiles into a unitary tile body. The unitary tile body is then removed from the mold and attached to a pole piece base to form the pole piece. The mold cavity surface preferably has a non-uniform contour. The bottom surface of the unitary tile body forms a substantially inverse contour of the mold cavity surface contour.

Abstract: A laminate tile pole piece for an MRI, a method and a mold for manufacturing laminate tile metal pole pieces for an MRI. Each laminate tile has a trapezoidal or annular sector shape. The trapezoidal shape allows the tiles to be attached side by side to form a multiple concentric annular array pole piece without using oddly shaped edge filler tiles needed to fill a circular pole piece with square tiles. The pole piece is made by placing a plurality of tiles into a mold and filling the mold with an adhesive substance to bind the plurality of tiles into a unitary tile body. The unitary tile body is then removed from the mold and attached to a pole piece base to form the pole piece. The mold cavity surface preferably has a non-uniform contour. The bottom surface of the unitary tile body forms a substantially inverse contour of the mold cavity surface contour.

Abstract: A laminate tile pole piece for an MRI. Each laminate tile has a trapezoidal or annular sector shape. The trapezoidal shape allows the tiles to be attached side by side to form a multiple concentric annular array pole piece without using oddly shaped edge filler tiles needed to fill a circular pole piece with square tiles. The pole piece is made by placing a plurality of tiles into a mold and filling the mold with an adhesive substance to bind the plurality of tiles into a unitary tile body. The unitary tile body is then removed from the mold and attached to a pole piece base to form the pole piece. The mold cavity surface preferably has a non-uniform contour. The bottom surface of the unitary tile body forms a substantially inverse contour of the mold cavity surface contour.

Abstract: A laminate tile pole piece for an MRI, a method and a mold for manufacturing laminate tile metal pole pieces for an MRI. Each laminate tile has a trapezoidal or annular sector shape. The trapezoidal shape allows the tiles to be attached side by side to form a multiple concentric annular array pole piece without using oddly shaped edge filler tiles needed to fill a circular pole piece with square tiles. The pole piece is made by placing a plurality of tiles into a mold and filling the mold with an adhesive substance to bind the plurality of tiles into a unitary tile body. The unitary tile body is then removed from the mold and attached to a pole piece base to form the pole piece. The mold cavity surface preferably has a non-uniform contour. The bottom surface of the unitary tile body forms a substantially inverse contour of the mold cavity surface contour.

Abstract: A closed magnetic resonance imaging (MRI) magnet has a single superconductive coil assembly including a toroidal-shaped coil housing containing a pair of superconductive main coils and at least one additional superconductive main coil. A pair of generally-non-permanently-magnetized ferromagnetic rings is spaced radially inward and apart from the superconductive main coils. The ferromagnetic rings allow the design of a shorter MRI magnet because the ferromagnetic rings overcome the gross magnetic field distortions in the imaging volume of the magnet (created by removing some of the additional longitudinally-outermost superconductive main coils, otherwise used in the magnet, to make the magnet shorter) to produce a magnetic field of high uniformity within the imaging volume.

Abstract: A closed magnetic resonance imaging (MRI) magnet has a single superconductive coil assembly including a toroidal-shaped coil housing containing a pair of superconductive main coils. A pair of generally annular-shaped bucking coils, carrying electric current in a direction opposite to that of the superconductive main coils, is spaced radially inward and apart from the superconductive main coils. The bucking coils allow the design of a shorter MRI magnet because the bucking coils overcome the gross magnetic field distortions in the imaging volume of the magnet (created by removing some of the additional longitudinally-outermost superconductive main coils, otherwise used in the magnet, to make the magnet shorter) to produce a magnetic field of high uniformity within the imaging volume.

Abstract: A closed magnetic resonance imaging (MRI) magnet has a single superconductive coil assembly including a toroidal-shaped coil housing containing a pair of superconductive main coils and at least one additional superconductive main coil. A pair of generally annular-shaped permanent magnet arrays is spaced radially inward and apart from the superconductive main coils. The permanent magnet arrays allow the design of a shorter MRI magnet because the permanent magnet arrays overcome the gross magnetic field distortions in the imaging volume of the magnet (created by removing some of the additional longitudinally-outermost superconductive main coils, otherwise used in the magnet, to make the magnet shorter) to produce a magnetic field of high uniformity within the imaging volume.

Abstract: A shielded and open magnetic resonance imaging (MRI) magnet having two spaced-apart, generally toroidal-shaped superconductive coil assemblies. Each coil assembly has a coil housing containing a generally annular-shaped superconductive main and a radially-outwardly spaced-apart shielding coil carrying electric currents in opposing directions. Preferably, supplemental shielding is provided with the addition of: a generally annular permanent magnet configuration internal to, or external of, the coil housings; a generally-non-permanently-magnetized external ferromagnetic shield having at least a portion positioned longitudinally between the coil housings, an external resistive coil; or combinations thereof.

Abstract: A magnet including spaced-apart first and second pole pieces with generally opposing first and second pole faces. The first pole face has an axis extending generally towards the second pole face and has a surface region which includes at least two frustoconical surfaces. The frustoconical surfaces are generally coaxially aligned about the axis, and radially-adjacent frustoconical surfaces abut each other. In a second embodiment, points on the surface region located an identical radial distance from the axis are also located a common axial distance along the axis, and a graph of axial distance along the axis versus radial distance from the axis for such points is a curve having a continuous slope with at least two sign reversals. Such contoured pole faces allow for a smoother magnetic field to better reduce axisymmetric magnetic field inhomogeneity.

Abstract: A superconductive magnet with magnetic shielding has an annularly-cylindrical-shaped housing whose first end wall and outer cylindrical wall are magnetizable (e.g., iron) walls and whose inner cylindrical wall is a non-magnetizable wall. At least one main superconductive coil is positioned within the housing and carries an electric current in a first (e.g., clockwise) direction. An annular first permanent magnet is positioned outside the housing longitudinally proximate the first end wall. The first permanent magnet has a number of equivalent ampere turns and has a magnetic field direction oriented parallel to the axis pointing towards the second end wall so that its magnetic field longitudinally pulls the stray magnetic field of the superconductive coil(s), which leaves the magnet's bore, inward to be captured by the iron first end wall.

Abstract: A superconductive magnet with magnetic shielding has an annularly-cylindrical-shaped housing whose first end wall and outer cylindrical wall are magnetizable (e.g., iron) walls and whose inner cylindrical wall is a non-magnetizable wall. At least one main superconductive coil is positioned within the housing and carries an electric current in a first (e.g., clockwise) direction. A first resistive (e.g., copper) deflection coil is positioned outside the housing radially proximate the outer cylindrical wall and longitudinally closer to the first end wall than to a midpoint located between the two end walls. The first deflection coil carries an electric current in an opposite direction to the first direction so that its magnetic field longitudinally pushes the stray magnetic field of the superconductive coil(s), which leaves the magnet's bore, inward to be captured by the iron first end wall.

Abstract: A magnet including spaced-apart first and second pole pieces with generally opposing first and second pole faces. The first pole face has an axis extending generally towards the second pole face and has a generally circular shim tray generally coaxially aligned with the axis and attached to the first pole face. The circular shim tray has shims each with a shape of generally a trapezoid when viewed facing the first pole face. The trapezoidal shaped shims may be arranged on the circumferences of imaginary concentric circles on the circular shim trays, with trapezoids on the same circumference having generally the same trapezoidal shape and with trapezoids on different circumferences having generally different trapezoidal shapes, to provide a smoother magnetic field to better reduce 3D (three-dimensional) magnetic field inhomogeneity.

Abstract: An open magnet having two magnet assemblies arranged in a spaced-apart, parallel relationship to define a working space therebetween is provided for magnetic resonance imaging. Each assembly has an annular superconductive coil and a ferromagnetic field enhancer encircled by the superconductive coil. The field enhancers are substantially cylindrical ferromagnetic pole pieces which are encircled by a respective one of the superconductive coils. The magnet assemblies are attached to a C-shaped support frame which is rotatively mounted to a pedestal member. The frame can thus be rotated between vertical and horizontal imaging positions. The field enhancers are shaped so as to maximize homogeneity in the imaging volume while keeping their weight and volume to a minimum. The specific shape of the field enhancers is determined with a nonlinear optimization design method.

Abstract: A magnetic resonance imaging (MRI) magnet having an annularly cylindrical-shaped vacuum enclosure with a longitudinal axis, first and second longitudinal ends, a first larger diameter bore extending from the first towards the second longitudinal end, and a second smaller diameter bore extending from the second longitudinal end to the first bore. First and second superconductive coils are placed in the vacuum enclosure with the first coil generally circumferentially surrounding the first bore and the second coil circumferentially surrounding the second bore, wherein the radial distance of the radially innermost portion of the second coil from the axis is smaller than the radius of the first bore. The first longitudinal end of the vacuum enclosure fits over a patient's shoulders with the patient's head at least partially passing through the first bore and extending into the second bore for MRI brain imaging.

Abstract: A magnetic resonance imaging (MRI) magnet having an annularly cylindrical-shaped vacuum enclosure with a longitudinal axis, first and second longitudinal ends, a first larger diameter bore extending from the first towards the second longitudinal end, and a second smaller diameter bore extending from the second longitudinal end to the first bore. First and second superconductive coils are placed in the vacuum enclosure with the first coil generally circumferentially surrounding the first bore and the second coil circumferentially surrounding the second bore, wherein the radial distance of the radially innermost portion of the second coil from the axis is smaller than the radius of the first bore. The second longitudinal end of the vacuum enclosure fits on a patient's shoulders with the patient's head passing through the second bore and extending into the first bore for MRI brain imaging.

Abstract: An open magnet having a frustoconical shaped inner bore is provided for MR imaging. The magnet has a plurality of axisymmetric superconducting coils of differing diameters which are disposed along an axis in order of successively increasing diameters so as to define the frustoconical shape. This shape permits a patient access opening which is much larger than that in conventional cylindrical magnets. The overall length is much less than the length of conventional systems. The combination of wide opening and short length facilitates patient access and presents a feeling of openness. Furthermore, the device can be tilted with respect to horizontal to increase the openness.

Abstract: An integrally shielded magnetic resonance magnet is provided comprising a cylindrical ferromagnetic shell and two ferromagnetic circular end plates each defining a central aperture extending axially therethrough. The end plates are welded vacuum leak tight at their peripheries to either end of the shell. A nonmagnetic cylindrical tube is welded vacuum leak tight between the central apertures of the end plates forming an axially extending bore through the cylindrical shell. The ferromagnetic shell and end plates are heated with rust inhibiting coatings. The end plates, shell and nonmagnetic tube form a vacuum vessel and shield. Magnet windings are situated in the vacuum vessel synthesized for operating in the presence of the ferromagnetic vessel.