Abstract: A Magnetic Resonance apparatus includes a 3D structure having a cavity for receiving a body under examination, a mechanism for generating a static magnetic field in the patient receiving cavity, a mechanism for generating variable magnetic fields in the cavity, an antenna for transmitting electromagnetic nuclear spin excitation pulses, an antenna for receiving the electromagnetic signals generated by nuclear spin relaxation, a plate for locating and fixing magnetic dipoles for fine correction of magnetic field homogeneity, and a compartment for the magnetic correction dipole locating and fixing plate, the compartment being adapted to be opened for direct access to the magnetic correction dipole locating and fixing plate from the outside. The compartment may be opened either by removal of an end plate of the magnetic field generating mechanism, or via a lateral slot for insertion and removal of the magnetic correction dipole locating and fixing plate.

Abstract: Method for making magnets particularly for the use in MRI scanners, which magnets are three-dimensional and have a tubular wall made of magnetized material, with a closed or open annular shaped cross-section, the tubular wall being composed of individual elements made of magnetized material, the magnetization of each element made of magnetized material having a predetermined direction in the transverse section plane and said directions being determined such to generate a uniform static magnetic field in the cavity of the tubular wall.

Abstract: An MRI apparatus having a magnet structure which delimits a cavity for receiving a body under examination or a part thereof, which includes a mechanism for generating a magnetic field in the cavity, as well as a mechanism for causing the body under examination or the part thereof to emit nuclear magnetic resonance signals, a region defined in the cavity, known as an imaging volume, and a mechanism for receiving the nuclear magnetic resonance signals. The geometric center of the geometric shape of the cavity delimited by the magnet structure is offset in relation to the geometric center of the imaging volume.

Abstract: An MRI apparatus including a magnetic structure defining a cavity for receiving a body under examination or a part thereof, a mechanism for generating a magnetic field inside the cavity, a mechanism for causing the body under examination or a part thereof to emit nuclear magnetic resonance signals, and a mechanism for receiving the nuclear magnetic resonance signals. The mechanism for generating the magnetic field includes one or more elements made of permanently magnetized material of the so-called superconducting bulk material type and, in combination therewith, a mechanism for keeping the magnetization condition of the superconducting bulk material which includes mechanisms for maintaining the temperature of the permanently magnetized material below the critical temperature thereof and for restoring the magnetization of the superconducting bulk material upon a complete or partial demagnetization.

Abstract: A Magnetic Resonance apparatus includes a 3D structure having a cavity for receiving a body under examination, a mechanism for generating a static magnetic field in the patient receiving cavity, a mechanism for generating variable magnetic fields in the cavity, an antenna for transmitting electromagnetic nuclear spin excitation pulses, an antenna for receiving the electromagnetic signals generated by nuclear spin relaxation, a plate for locating and fixing magnetic dipoles for fine correction of magnetic field homogeneity, and a compartment for the magnetic correction dipole locating and fixing plate, the compartment being adapted to be opened for direct access to the magnetic correction dipole locating and fixing plate from the outside. The compartment may be opened either by removal of an end plate of the magnetic field generating mechanism, or via a lateral slot for insertion and removal of the magnetic correction dipole locating and fixing plate.

Abstract: Method for making magnets particularly for the use in MRI scanners, which magnets are three-dimensional and have a tubular wall made of magnetized material, with a closed or open annular shaped cross-section, the tubular wall being composed of individual elements made of magnetized material, the magnetization of each element made of magnetized material having a predetermined direction in the transverse section plane and said directions being determined such to generate a uniform static magnetic field in the cavity of the tubular wall.

Abstract: An MRI apparatus comprising a magnet structure which delimits a cavity for receiving a body under examination or a part thereof, and which includes means for generating a magnetic field in said cavity, as well as means for causing the body under examination or the part thereof to emit nuclear magnetic resonance signals, a region being defined in the cavity, known as imaging volume, and means for receiving the nuclear magnetic resonance signals. The MRI apparatus also comprises an electronic processing unit with which the means for receiving the nuclear magnetic resonance signals are electrically connected; the cavity has an access opening for receiving a body under examination or part thereof. The geometric center of the geometric shape of the cavity delimited by the magnet structure is in offset relation to the geometric center of the imaging volume.

Abstract: A magnet structure for an MRI apparatus utilizing a permanent magnet, which apparatus has an inverted U shape with two essentially parallel opposed pole pieces, which are supported at a predetermined distance from each other by an inverted U-shaped magnetic yoke, which pole pieces and/or at least a portion of which yoke delimit a cavity for receiving at least a part of the patient's body, whereas a partial volume is generated in the volume of said cavity, which has such magnetic field values as to provide MRI images of a sufficient quality to enable the use thereof as diagnostic images, i.e. a so-called imaging volume. According to the invention, the distance (D1) between the pole pieces (1, 2) of the magnet structure is of 36 to 42 cm, and the pole pieces (1, 2) have a surface area of 4500 to 5500 cm2. The invention also relates to an MRI imaging apparatus, particularly designed for the spine region, or a part thereof, and which has a magnet structure as described above.

Abstract: An MRI apparatus including a magnetic structure defining a cavity for receiving a body under examination or a part thereof, a mechanism for generating a magnetic field inside the cavity, a mechanism for causing the body under examination or a part thereof to emit nuclear magnetic resonance signals, and a mechanism for receiving the nuclear magnetic resonance signals. The mechanism for generating the magnetic field includes one or more elements made of permanently magnetized material of the so-called superconducting bulk material type and, in combination therewith, a mechanism for keeping the magnetization condition of the superconducting bulk material which includes mechanisms for maintaining the temperature of the permanently magnetized material below the critical temperature thereof and for restoring the magnetization of the superconducting bulk material upon a complete or partial demagnetization.

Abstract: A magnet structure for a Nuclear Magnetic Resonance imaging apparatus includes at least two opposing magnetic pole pieces, which are located at a certain distance from each other and delimit an imaging region. The pole pieces are formed by at least one massive layer of a magnetically permeable material, and at least one layer of magnetically permeable material having a pack of superimposed sheets or foils, electrically insulated from each other. Each of the sheets has cuts arranged over the surface of the sheet in positions that are at least partly non coincident with the cuts of at least one, or both adjacent sheets. The magnetically permeable sheets or foils have a first face and a second face and the cuts are so arranged on each sheet that the cuts of a sheet or foil are offset and not coincident with respect to the cuts of an adjacent sheet or foil, when said adjacent sheet is laid over the previous sheet in an overturned position, i.e.

Abstract: Magnetic structure for MRI machines, which machine has a U-shaped or annular, that is O-shaped geometry having two opposite poles between which a magnetic field is generated and are borne at a predetermined distance one with respect to the other by a magnetic yoke having an inverted U shape or an annular one, that is an O shape, which poles generating the magnetic field and/or at least a part of which yoke delimit a cavity housing at least a part of the patient body, while inside the volume of said cavity a partial volume is generated wherein values of the magnetic field are such to guarantee the acquisition of MRI images having quality characteristics sufficient to be used like diagnostic images, so called imaging volume. The invention relates also to a machine for detecting MRI images particularly of the anatomical region of the hand or the foot or part of joints and which machine has a magnetic structure of the type described above.

Abstract: A method for compensating in a space volume for a magnetic noise field outside the space volume includes determining a strength of the magnetic noise field outside the space volume; defining a correlation between the noise field outside the space volume and a corresponding noise field inside the space volume, or calculating the noise field inside the space volume on the basis of the measurements of the magnetic field outside the space volume; based on the noise field inside the space volume, generating a magnetic compensation field for neutralizing the noise field inside the space volume; wherein the compensation of the magnetic noise field outside the space volume is carried out along a direction in the space volume which is variable by determining a noise field component inside the space volume along the direction and generating a compensation field of the noise field component along the direction.

Abstract: A method for determining construction parameters of magnet structures designed to generate magnetic fields in predetermined volumes of space, comprising the steps of: a) defining a predetermined volume of space in which a static magnetic field is to be generated; b) defining the nominal strength and profile of the magnetic field in said predetermined volume of space; c) mathematically describing the nominal magnetic field on the surface of and/or in said predetermined volume of space by using a polynomial expansion of the magnetic field-describing function, which provides a series of coefficients; d) determining the size, geometry and relative position in space of the means for generating said nominal magnetic field, with respect to the volume of space in and on which the desired, i.e. nominal magnetic field, is defined.

Abstract: A magnet for a Magnetic Resonance Imaging apparatus, said magnet having at last two, preferably three open sides, and delimiting the patient receiving area, said magnet being composed of three yoke elements, i.e. two parallel magnetically permeable elements and one transverse yoke element for connection of said two parallel elements, whereby said magnet has a C shape and wherein, for both of said parallel elements, the terminal portion associated to said transverse connecting element has a transverse wall for connection of said two parallel elements with the transverse element, which has an end step for engagement of a corresponding end of said transverse element.

Abstract: Magnetic structure for MRI machines, which machine has a U-shaped or annular, that is O-shaped geometry having two opposite poles between which a magnetic field is generated and are borne at a predetermined distance one with respect to the other by a magnetic yoke having an inverted U shape or an annular one, that is an O shape, which poles generating the magnetic field and/or at least a part of which yoke delimit a cavity housing at least a part of the patient body, while inside the volume of said cavity a partial volume is generated wherein values of the magnetic field are such to guarantee the acquisition of MRI images having quality characteristics sufficient to be used like diagnostic images, so called imaging volume. The invention relates also to a machine for detecting MRI images particularly of the anatomical region of the hand or the foot or part of joints and which machine has a magnetic structure of the type described above.

Abstract: An exemplary method for correcting inhomogeneities of the static magnetic field generated by the magnetic structure of a machine for acquiring nuclear magnetic resonance images includes determining the number, the position and the magnetic moment of dipoles compensating inhomogeneities of the magnetic field to be positioned on a positioning grid such that a function is minimized. The total magnetic moment of compensation dipoles for compensating the magnetic field inhomogeneity can be minimized in addition to minimizing a norm of the difference between an inhomogeneity vector of each of the magnetic field components and the linear combination of effect vectors corresponding to the magnetic field component of compensation dipoles.

Abstract: A magnet for a Magnetic Resonance Imaging apparatus, said magnet having at last two, preferably three open sides, and delimiting the patient receiving area, said magnet being composed of three yoke elements, i.e. two parallel magnetically permeable elements and one transverse yoke element for connection of said two parallel elements, whereby said magnet has a C shape and wherein, for both of said parallel elements, the terminal portion associated to said transverse connecting element has a transverse wall for connection of said two parallel elements with the transverse element, which has an end step for engagement of a corresponding end of said transverse element.

Abstract: A magnet structure for an MRI apparatus utilizing a permanent magnet, which apparatus has an inverted U shape with two essentially parallel opposed pole pieces, which are supported at a predetermined distance from each other by an inverted U-shaped magnetic yoke, which pole pieces and/or at least a portion of which yoke delimit a cavity for receiving at least a part of the patient's body, whereas a partial volume is generated in the volume of said cavity, which has such magnetic field values as to provide MRI images of a sufficient quality to enable the use thereof as diagnostic images, i.e. a so-called imaging volume. According to the invention, the distance (D1) between the pole pieces (1, 2) of the magnet structure is of 36 to 42 cm, and the pole pieces (1, 2) have a surface area of 4500 to 5500 cm2. The invention also relates to an MRI imaging apparatus, particularly designed for the spine region, or a part thereof, and which has a magnet structure as described above.

Abstract: A method for determining construction parameters of magnet structures designed to generate magnetic fields in predetermined volumes of space, comprising the steps of: a) defining a predetermined volume of space in which a static magnetic field is to be generated; b) defining the nominal strength and profile of the magnetic field in said predetermined volume of space; c) mathematically describing the nominal magnetic field on the surface of and/or in said predetermined volume of space by using a polynomial expansion of the magnetic field-describing function, which provides a series of coefficients; d) determining the size, geometry and relative position in space of the means for generating said nominal magnetic field, with respect to the volume of space in and on which the desired, i.e. nominal magnetic field, is defined.

Abstract: Method for correcting inhomogeneities of the static magnetic field particularly of the static magnetic field generated by the magnetic structure of a machine for acquiring nuclear magnetic resonance images provides to determine the number, the position and the magnetic moment of dipoles compensating inhomogeneities of the magnetic field to be positioned on a positioning grid such to minimize a function wherein even the total magnetic moment of compensation dipoles provided for compensating the magnetic field inhomogeneity is minimized in addition to minimizing said certain norm of the difference between the inhomogeneity vector of each magnetic field components and the linear combination of effect vectors corresponding to said magnetic field component of compensation dipoles.