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.

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: 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: A magnetic resonance imaging apparatus including a magnetic structure having two opposite and spaced apart poles and a column or wall transverse to the poles and connecting the poles; the poles defining two opposite walls delimiting a patient-imaging space, the two opposite walls extending along substantially parallel planes which are substantially parallel to a vertical plane; and a patient positioning table which is slidably connected to a supporting frame between the two poles; the table being positioned with its longitudinal axis substantially parallel to the two opposite parallel walls of the poles and the table being oriented with its transverse axis perpendicular to at least one of the two opposite walls.

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: The invention relates to a process for manufacturing magnetic field generating devices in Nuclear Magnetic Resonance imaging apparatuses and to an image generating device according to said method. According to the invention, at least one layer of each pole piece is composed a plurality of adjacent or overlapping sheets, electrically insulated from each other. These sheets or foils may have slots, notches or apertures which cause bridges of a material having a lower electric conductivity to be formed between the areas separated by the notches and/or apertures. The bridges of material may be removed after sheet assembly by a cutting operation, particularly by laser cutting.

Abstract: The invention is directed to a method, an instrument and a system for performing verification measurements and corrections of magnetic fields in magnets for Nuclear Magnetic Resonance imaging machines. According to the invention, test elements are used whereof Nuclear Magnetic Resonance images are detected. Then, these actually detected images are compared with the theoretical images which would be obtained in ideal conditions. The number, magnitude and position of correcting magnetic charges are determined from the differences between the actual image and the theoretical image. The invention is also directed to a specific test element and to a Nuclear Magnetic Resonance imaging machine.

Abstract: The invention relates to a process for manufacturing magnetic field generating devices in Nuclear Magnetic Resonance imaging apparatuses and to an image generating device according to said method. According to the invention, at least one layer of each pole piece is composed a plurality of adjacent or overlapping sheets, electrically insulated from each other. These sheets or foils may have slots, notches or apertures which cause bridges of a material having a lower electric conductivity to be formed between the areas separated by the notches and/or apertures. The bridges of material may be removed after sheet assembly by a cutting operation, particularly by laser cutting.

Abstract: The invention is directed to a method, an instrument and a system for performing verification measurements and corrections of magnetic fields in magnets for Nuclear Magnetic Resonance imaging machines. According to the invention, test elements are used whereof Nuclear Magnetic Resonance images are detected. Then, these actually detected images are compared with the theoretical images which would be obtained in ideal conditions. The number, magnitude and position of correcting magnetic charges are determined from the differences between the actual image and the theoretical image. The invention is also directed to a specific test element and to a Nuclear Magnetic Resonance imaging machine.

Abstract: A method for correcting and/or calibrating magnetic fields, particularly intended for magnets in nuclear magnetic resonance imaging equipment, involves the mathematical description of the field generated by a magnet structure with a harmonic polynomial expansion and the determination of the number, position and magnetization distribution parameters on a predefined distribution grid, related to the magnetic structure, by comparing the polynomial expansion coefficients obtained from a sampling measurement of the actual field with the coefficients of the field having the desired characteristics.

Abstract: A magnet structure, particularly for Nuclear Magnetic Resonance imaging machines, and of the type having a bearing structure for means for generating magnetic fields inside a volume, a cavity or similar space, defined by the structure, is made to be modular at least for part of the bearing structure, and/or at least for part of the other construction elements.

Abstract: A permanent magnet for nuclear magnetic resonance image detection, includes a magnetic structure having a yoke and magnetic poles, so shaped as to delimit or enclose a cavity, at least a part of a volume of the cavity forms a compartment for receiving at least a part of a body under examination, and at least a part of the volume of the cavity is permeated by a static magnetic field having specific intensity and homogeneity characteristics; the magnetic structure has at least one open side, parallel to the static magnetic field; the magnetic structure has at least two opposite main poles, lying face to face, transverse to the open side, the static magnetic field being generated therebetween; in the vicinity of the open side, the magnet has a device for correcting the static magnetic field generated between the main poles, the correction device including an element for increasing the magnetic potential near the open side, and over a predetermined depth therefrom, transverse to the open side, without reducing th

Abstract: A magnetic structure for generating magnetic fields to be used in nuclear magnetic resonance image detection, having means (1, 101, 201, 301, 101', 201', 101", 201", 3, 3') for generating a magnetic field with the characteristics required to obtain valid images inside a predetermined tridimensional area (102), being at least a part of a cavity (2), which is at least partially contained in the magnetic structure. According to the invention, the means for generating the magnetic field consist of at least one coil (3, 3'), of the resistive or superconductive type.