Abstract: A local or surface coil including a decoupling circuit to allow the coil to operate as a receive-only coil in a host MRI system, in which case the system body coil typically provides the transmit signal. Further, the local or surface coil includes a circuit to defeat the decoupling circuitry for both low power [receive] and high power [transmit] functions to allow the same physical coil to be used as a transmit/receive coil in addition to a receive-only coil. The two modes of the coil allow the user to select the mode of local or surface coil operation best suited to the particular type of imaging being performed.

Abstract: A magnet coil arrangement comprising an actively shielded superconducting primary circuit (21) comprising first and second magnet windings (1,2,3 and 4,5), and being wound e.g. in winding chambers (7,8,9 and 10,11) in a supporting body (6a,6b) for generating a strong magnetic field in a working volume with a small magnetic stray field and a short circuited secondary circuit (22) which is inductively coupled with the primary circuit (21) and contains third and fourth magnet windings (13,14,15 and 16,17) is characterized in that the magnet windings (13,14,15 and 16,17) of the secondary circuit (22) form an actively shielded magnet coil. This permits a simple and robust coil protection for actively shielded superconducting magnets during a quench wherein the superconducting magnet windings are reliably relieved and the magnetic stray field of the entire arrangement remains small.

Abstract: A permanent magnet for an MRI scanner is made by removing extraneous elements from an ore containing rare earth elements to leave elements Pr and Nd therein, and then selectively stripping therefrom a portion of the element Nd as a byproduct to leave an ore residuum including both elements Pr and Nd therein. The residuum is alloyed with a transition metal to form an alloy therewith. The alloy is then formed into a rare earth permanent magnet configured for use in the MRI scanner.

Abstract: A main field magnet arrangement for a one-sided magnet resonance device produces a homogeneous magnetic field B in a working volume (4). The working volume (4) and the main field magnet (1) are disposed on different sides of a plane E and the main field magnet (1) has a geometric shape which permits disposal of a radio frequency (RF) receiver coil system and optionally a gradient coil system on the same side of the plane E as the main field magnet (1). Field-generating elements of permanent-magnetic material form a radially outer part (2) and a radially inner part (3) relative to an axis A extending through the center of the working volume (4), wherein the surface, facing the working volume (4), of the radially inner part (3) is axially further spaced apart from the center of the working volume (4) than the surface of the radially outer part (2) facing the working volume (4), such that a depression (5) is formed in the radially inner part (3) in the axial direction.

Abstract: The temperature of permanent magnet blocks embedded in several positions in permanent magnets and base yokes will be adjusted by device of a heater to improve the static field uniformity.

Abstract: A gradient coil system for a magnetic resonance apparatus has at least one gradient coil for generating a magnetic gradient field at least within an imaging volume, the gradient field having a main field component co-linear with a basic magnetic field and at least one accompanying field component perpendicular to the main field component, and an electrically conductive shield for shielding the accompanying field component, at least toward the imaging volume.

Abstract: A magnet assembly system for use in an open Magnetic Resonance Imaging (MRI) system comprises a first assembly and a second assembly opposing each other in a longitudinally spaced apart relationship. The first and second assemblies generate a static magnetic field for use in imaging. Further provided is a plurality of support posts attached between the first and second assemblies for maintaining an open imaging volume between the first and second assemblies and for further providing structural support. Each of the support posts comprises a first support element and a second support element attached to first support element on the surface away from the imaging volume. A method for reducing vibration in an open MRI system comprises attaching a second support element to each of the support posts on a surface away from the imaging volume.

Abstract: A magnetic resonance imaging (MRI) magnet in combination with a mobile patient-positioning device, including a patient support and a method of using same for positioning patients for MRI scanning. The patient support is rotatable through a range of orientations from a horizontal to a vertical position, including being lockable at any oblique angle with respect to the horizontal. The patient disposed on the patient-positioning device in a predetermined orientation can then be moved horizontally into and out of a patient-receiving space in the MRI magnet at the predetermined angle or orientation. A preferred embodiment includes a plurality of patient-positioning devices in which a series of patients can be placed in a ready state while one patient is within the patient-receiving space. As an alternative embodiment, the patient may be moved vertically into position for MRI scanning by way of an elevator which is actuatable from the floor below the patient receiving space.

Abstract: A pole piece for use in an open magnet includes a magnetizable body of generally cylindrical shape and made of a ferromagnetic material with a plurality of concentrically-arranged, annular-shaped, radially spaced-apart grooves formed in the inner surface of the pole piece. A plurality of annular-shaped, electrically conductive coils are disposed within the grooves. The pole piece with recessed shielding coils is situated within a cryogenic vessel to maintain the pole pieces at a uniform cryogenic temperature. The result is an open magnet structure which provides a highly uniform, high field, open field of view for MRI with a well-contained stray field.

Abstract: The invention concerns a gradient system of a magnetic resonance apparatus comprising an additional, rigidly mechanically coupled highly conductive shielding cylinder which dampens excitation of mechanical vibrations of the apparatus during gradient switching.

Abstract: A superconducting magnet arrangement (M, S, P1, . . . , Pn) for generating a magnetic field in the direction of a z axis in a working volume, disposed about z=0, comprising a magnet coil system (M) with at least one current-carrying superconducting magnet coil, a shim device (S) with at least one superconducting shim coil and additional superconductingly closed current paths (P1, . . . , Pn), wherein the magnetic fields generated in the z direction and in the working volume by the additional current paths due to induced currents during operation, do not exceed a magnitude of 0.1 Tesla, and wherein the shim device generates a field which varies along the z axis with a kth power of z for an even power of k>0, is characterized in that the shim device is designed such that the effective field efficiency gSeff of the shim device is substantially zero taking into consideration the diamagnetism of the superconductor in the magnet coil system.

Abstract: The invention describes an acoustic liner for use with a magnetic field gradient coil, especially for use in magnetic resonance imaging (MRI) systems. The liner comprises an acoustic sheet (12), preferably of compressible material, adapted to be fitted to the gradient coil, and an acoustic conducting path (10) for carrying an electrical current provided on or in the sheet, arranged such that in use a current pulse can be applied to the gradient coil and a current pulse can be applied to the acoustic conducting path in synchronism therewith, wherein the acoustic conducting path is arranged such that Lorentz forces on the acoustic conducting path in a magnetic field cause the acoustic conducting path to move relative to the gradient coil in such a way that the inner surface (9) of said acoustic sheet remains substantially stationary.

Abstract: A gradient coil system and magnetic resonance apparatus having the gradient coil system is provided in which the gradient coil system comprises a first and a second transverse gradient coil, these coils being arranged alongside each other axially offset on a common cylinder envelope, where the cylinder envelope has at least one circumferential line which is overlapped by both gradient coils.

Abstract: A gradient coil assembly generates magnetic field gradients across the main magnetic field of a magnetic resonance imaging apparatus and includes a primary gradient coil (22p) switchable between a first configuration which generates magnetic field gradients which are substantially linear over a first useful imaging volume, and a second configuration which generates magnetic field gradients which are substantially linear over a second useful imaging volume. A first shield coil set (22s1) is complimentary to the primary gradient coil in one of the first and second configurations, and a second shield coil set (22s2), when either used alone or in combination with the first shield coil, is complimentary to the other of the first and second configurations.

Abstract: A superconducting magnet system for generating a magnetic field in the direction of a z axis in a working volume disposed about z=0 with at least one current-carrying magnet coil (M) and with at least one additional, superconductingly closed current path (P1, . . . , Pn), which can react inductively to the changes of the magnetic flux through the area enclosed by it, wherein the magnetic fields in the z direction in the working volume which are produced by these additional current paths during operation and due to induced currents, do not exceed a magnitude of 0.1 Tesla, is characterized in that, when an additional disturbance coil (D) produces a substantially homogeneous disturbance field in the magnet volume, the diamagnetic expulsion of the disturbance field from the main magnet coil is taken into consideration when designing the magnet coil(s) and the current paths.

Abstract: A magnetic resonance apparatus comprises a soundproofing structure that contains a material having an effectively negative elasticity constant.

Abstract: The invention relates to an MR method in which the nuclear magnetization is enhanced under the influence of a first steady magnetic field and a second steady magnetic field acts on the nuclei previously influenced by the first magnetic field. According to the invention, the two magnetic fields overlap in time and enclose an angle other than 0° relative to one another, the angle preferably amounting to 90°. The enhanced nuclear magnetization is then sustained after the activation of the first steady magnetic field while the direction of the nuclear magnetization is determined by the second steady magnetic field. The use of two mutually perpendicular magnetic fields is advantageous notably for Overhauser imaging methods, because it enables the use of mutually perpendicular RF fields for the ESR saturation and the MR excitation, thus uncoupling the coils generating such RF fields from one another.

Abstract: An open or split type MRI apparatus has two axially spaced magnet coil half sections separated and supported by a compact support structure. Only two diametrically opposed supports are needed to react the high axial and torsional loads produced or received by the MRI apparatus. One support is loaded under pure compression, and the other support is loaded under compression and tension.

Abstract: The present invention is intended to provide an ethylene copolymer having excellent mechanical properties and moldability, a process for preparing the copolymer, a resin composition containing the copolymer and uses thereof. The ethylene copolymer has the following properties: the copolymer comprises 90 to 99% by mol of ethylene constituent units and 1 to 60% by mol of C3-20 &agr;-olefin constituent units; the ratio (Mz/Mw) of a Z average molecular weight (Mz) to a weight-average molecular weight (Mw), each molecular weight being measured by GPC, is in the range of 10 to 30, and said ratio (Mz/Mw) and the ratio (Mw/Mn) of a weight-average molecular weight (Mw) to a number-average molecular weight (Mn), each molecular weight being measured by GPC, satisfy the relation (Mz/Mw)>(Mw/Mn); the intrinsic viscosity is in the range of 0.5 to 9 dl/g; the ratio (n*0.01/n*8) of a melt viscosity (&eegr;*0.01) at a shear rate of 0.01 rad/sec, as measured at 190° C.

Abstract: An open architecture platform superconducting magnet for international procedures with a shaped yoke assembly and associated magnet coil and with a patient support positioned above the magnet coil, and a magnetic field imaging volume which is conically shaped with a cross section which decreases in size remote from the coil.

Abstract: A shim device for a magnetic resonance apparatus has a cavity for the acceptance of shim elements, the cavity being arranged in an antenna conductor.

Abstract: A method for generating a ferromagnetic shim calibration file includes the steps of performing a computation of an analytical Finite Element solution of an internal magnetic field for each location where a shim is assumed to be present in an imaging volume of a magnet, performing a computation of an equivalent magnetic dipole moment of a shim with a saturated magnetization using the analytical Finite Element solution of the internal magnetic field, making a correction of the computation of the equivalent magnetic dipole moment of the shim to compensate for an aspect ratio for the shape of the shim, making another correction of the corrected computation of the equivalent magnetic dipole moment of the shim to compensate for a magnetic mirror effect in a pole-face of the magnet, and storing all computations and corrections for each shim in a shim calibration file.

Abstract: Within upper and lower cryostats 17 and 18 for a super conducting magnet 2 level sensor 215 and 216 which measure respective amounts of liquid helium 212 therein are assembled and are connected to a measuring circuit 23. When a control signal of a computer 10 is provided to the measurement circuit 23 via the sequencer 9, the measurement circuit 23 performs automatic measurement of remaining amount of liquid helium 212 and the measured data is transferred to the computer 10. The computer 10 records the measured data as well as performs computation processing thereof and causes a display unit 12 to display the processing result as an effective management parameter of the liquid helium. Thereby, an open type MRI apparatus using a super conducting magnet with liquid helium monitoring system which is suitable for maintenance and management of liquid helium for the super conducting magnet can be provided.

Abstract: NMR apparatus for achieving construction of improved patient access. Facilities and methods of mobile and fixed site scanning.

Abstract: A magnet for magnetic resonance imaging has an interior working space within the magnet frame sufficient to accommodate a physician and a patient. Because the physician is positioned inside the magnet frame, the physician has unimpeded access to the patient. Elements of the magnet frame desirably encompass a room, and the magnet frame may be concealed from view of a patient within the room. Preferred embodiments facilitate MRI imaged guided surgery and other procedures performed while the patient is being imaged, and minimize claustrophobia experienced by the patient. Also provided is a magnet having field coils disposed about the of pole portions of the magnet. A diagnostic facility for high volume MRI use is also disclosed.

Abstract: The invention relates to a medical examination apparatus (1) which includes at least one switchable magnet whose magnetic field can be applied to an organism to be examined in the operating condition. The invention notably relates to an examination apparatus (1) which includes a coil (3) that generates a magnetic field when current flows therethrough, and also includes a receiving space (2) that is provided in the interior of the coil so as to receive the organism to be examined, the examination apparatus (1) being mounted on the floor (5) and being constructed in such a manner that a noise-absorbing material (16) is provided in a plane that is situated underneath the magnet (3).

Abstract: An acoustically quiet gradient coil structure for a magnetic resonance imaging system, said coil structure comprising one or more conductors embedded in a plate of acoustically transmitting material, said plate having one or more edge surfaces characterized in that at least one edge surface (100, 102, 104, 106) of said plate is chamfered. The plate may comprise a composite cellular structure of cellular materials having positive and negative Poisson's ratio &sgr; such that the overall &sgr; is substantially zero.

Abstract: A low noise imaging apparatus for producing Magnetic Resonance (MR) images of a subject and for substantially minimizing acoustic noise generated during imaging is provided. The imaging apparatus comprises a magnet assembly, a gradient coil assembly, and a rf coil assembly, wherein at least one of the magnet assembly, the gradient coil assembly and the rf coil assembly are configured to reduce the generation and transmission of acoustic noise.

Abstract: A flexible peripheral coil for magnetic resonance imaging provides a tapered volume conforming to a patient through the use of multiple flexible leaves of decreasing combined length which enclose progressively smaller cylindrical areas while maintaining correct coil orientation. A freestanding foot coil may be placed over the patient's foot with toes passing through an aperture in the coil to complete the scanning coverage area. Straps allow the various coil leaves to accommodate different body sizes effectively varying the taper of the coil.

Abstract: A superconducting magnet apparatus. By forming one or more holes in each of platelike ferromagnetic substances forming a magnetic shield for focusing the magnetic flux generated by superconducting coils, the flow of lines of magnetic flux is adjusted. Thereby, a static magnetic field in a measurement space is corrected. By disposing coupling tubes for supporting two cooling vessels housing superconducting coils on the rear side with respect to a central axis (Z axis) of the measurement space of the vertical direction, access to the subject is facilitated. In addition, the magnetic shield has an opening portion wider than the superconducting magnet on its side face. After the magnetic shield has been assembled, the superconducting magnet can be inserted from the opening portion.

Abstract: An apparatus for supporting a patient support bridge member in an MR system where a first end of the bridge is supported by an upright support member on a first side of an MR imaging bore and the bridge extends through the bore so that a second end of the bridge extends out a second side of the bore, the apparatus including a bracket mounted to an MR main magnet on the second side of the bore and extending upwardly to contact and support the bridge there above.

Abstract: The invention relates to an MR apparatus with three gradient coils, the differences between said gradient coils are reduced in that the gradient directions extend obliquely to the direction of the main magnetic field.

Abstract: (A) This invention of the flexible, expandable, & retractable balloon (FERB) RF internal receiving coil is aimed at addressing the key areas of interest such as the enhancement of the MR image performance at the local areas/volume of the patient organs being studied, the provision of images beyond the tissue walls where the Endoscopy fails to provide, the designs of the shape and size of the balloon/RF coil insert to fit into the patient organs' contours and into a greater depth such as the intestines etc . . . the user friendliness and comfort, and, the meting the health and safety requirements. Whereas the existing internal RF coil designs fail to address either partly, or mostly. A rigid-rod cervix RF receiving coil and its disposable outer shell are also included into the invention.

Abstract: The image produced by a magnetic resonance imaging apparatus using a receive coil 2 has inaccuracies due to external circumstances which affect the signal produced by the coil 2. Thus, noise spikes affect the signal, although more usually extensive shielding is provided. Also, changes of loading of the coil produced by movement of the patient vary the Q of the coil and hence the signal output. In accordance with a first aspect of the invention, a second coil 4 superimposed on the coil 2 is tuned to a frequency offset compared to the MR center frequency and is used to monitor coil loading to enable the signal from coil 2 to be corrected, and in accordance with a second aspect of the invention an additional coil 4 or 8, preferably both, is/are provided in order to detect broadband noise and enable its suppression on the output of the coil 2.

Abstract: A magnetic resonance imaging (MRI) magnet in combination with a mobile patient-positioning device, including a patient support and a method of using same for positioning patients for MRI scanning. The patient support is rotatable through a range of orientations from a horizontal to a vertical position, including being lockable at any oblique angle with respect to the horizontal. The patient disposed on the patient-positioning device in a predetermined orientation can then be moved horizontally into and out of a patient-receiving space in the MRI magnet at the predetermined angle or orientation. A preferred embodiment includes a plurality of patient-positioning devices in which a series of patients can be placed in a ready state while one patient is within the patient-receiving space. As an alternative embodiment, the patient may be moved vertically into position for MRI scanning by way of an elevator which is actuatable from the floor below the patient receiving space.

Abstract: Adjustable hybrid magnetic apparatus for use in medical and other applications includes an electromagnet flux generator for generating a first magnetic field in an imaging volume, and permanent magnet assemblies for generating a second magnetic field superimposed on the first magnetic field for providing a substantially homogenous magnetic field having improved magnitude within the imaging volume. The permanent magnet assemblies may include a plurality of annular or disc like concentric magnets spaced-apart along their axis of symmetry. The electromagnet flux generator may include two electromagnet assemblies. The electromagnet assemblies and the permanent magnet assemblies may be static assemblies or may be movable and/or tiltable and/or movable and tiltable, for fine tuning of the magnetic field within the imaging volume. The hybrid magnetic apparatus may include a high magnetic permeability yoke for increasing the intensity of the magnetic field in the imaging volume of the hybrid magnetic apparatus.

Abstract: Low-temperature (cryogenic) radio-frequency (RF) coils for nuclear magnetic resonance (NMR) applications include composite multi-layered structures including an internal normal metal layer clad on both sides by external high-purity annealed aluminum layers. The magnetic susceptibilities of the internal and external layers are opposite in sign, and the thicknesses of the layers are chosen such that the composite structure has a net magnetic susceptibility equal to that of its surroundings (vacuum or support material). The internal layer can have a higher resistivity and magnetoresistance than the external layers. The use of high-purity, annealed aluminum for the external layers allows relatively high Q-factors for the cryogenic coils.

Abstract: A radio frequency (RF) coil system for resonance imaging/analysis comprising a primary coil element having a plurality of axial conductors spaced to form a generally tubular structure having two ends and defining a coil volume, and a first pair of spoiler coils. The first pair of spoiler coils each comprising a plurality of axial conductors spaced to form a generally tubular structure and defining a coil volume. Each of the spoiler coils is positioned adjacent to and overlapping an end of the primary coil. Each of the primary and spoiler coils is also adapted to carry an RF signal, wherein the signal in the spoiler coils is 180 degrees out of phase with the signal in the primary coil. The counter-phased spoiler coils act to rapidly drive down the RF magnetic field generated by the primary coil in the region of the ends of the primary coil to reduce the occurrence of aliasing artifacts from outside the imaging field of view.

Abstract: The present invention is directed to a nuclear magnetic resonance apparatus and method for generating an axisymmetric magnetic field having long, straight contour lines in the resonance region. A magnetically permeable member is used to shape the static magnetic field generated by an array of permanent magnets. The magnetically permeable member minimizes variations of the static magnetic field in the formation due to vertical motion of the apparatus while obtaining a nuclear magnetic resonance measurement. Further, the magnetically permeable member may minimize variations of the static magnetic field in the formation due to lateral motion of the apparatus while obtaining a nuclear magnetic resonance measurement.

Abstract: NMR apparatus for achieving construction of improved patient access. Facilities and methods of mobile and fixed site scanning.

Abstract: The invention concerns a method of correcting field inhomogeneities of higher order in a magnetic resonance apparatus After an excitation pulse and action of a phase gradient in a predetermined direction p, a data point is recorded after two predetermined times td1 and td2. This is repeated for systematically modified strengths of the phase gradient and constant td1 and td2, and two sets of signal dependences in the p direction are obtained. The two phase dependences of the two Fourier transformed data sets in the p direction are subtracted. The profile of the difference phase in the p direction corresponds to a field error profile. The method is repeated for several p directions, and coefficients of higher order of a series expansion of the field inhomogeneities in spherical harmonic functions are obtained.

Abstract: A magnetic resonance apparatus has a gradient coil system that includes a gradient coil arrangement with a conductor and magnetostrictive material, and contains a basic field magnet system for generating a basic magnetic field. The magnetostrictive material is thereby arranged in the immediate proximity of the conductor in regions having the same course as a course of the conductor, to suppress noise-producing vibrations.

Abstract: A permanent magnet for an MRI scanner is made by removing extraneous elements from an ore containing rare earth elements to leave elements Pr and Nd therein, and then selectively stripping therefrom a portion of the element Nd as a byproduct to leave an ore residuum including both elements Pr and Nd therein. The residuum is alloyed with a transition metal to form an alloy therewith. The alloy is then formed into a rare earth permanent magnet configured for use in the MRI scanner.

Abstract: NMR apparatus for achieving construction of improved patient access. Facilities and methods of mobile and fixed site scanning.

Abstract: A magnet for magnetic resonance imaging has an interior working space within the magnet frame sufficient to accommodate a physician and a patient. Because the physician is positioned inside the magnet frame, the physician has unimpeded access to the patient. Elements of the magnet frame desirably encompass a room, and the magnet frame may be concealed from view of a patient within the room. Preferred embodiments facilitate MRI imaged guided surgery and other procedures performed while the patient is being imaged, and minimize claustrophobia experienced by the patient. Also provided is a magnet having field coils disposed about the of pole portions of the magnet. A diagnostic facility for high volume MRI use is also disclosed.

Abstract: In order to reduce the electric current loss and the heat release in a shielding coil, partially shielding coils 1Zts and 1Zbs are employed having their windings positioned corresponding only to a high winding density zone 1Zp, rather than corresponding to the entire winding area, of main gradient coils 1Zt and 1Zb.

Abstract: An iterative method of homogenizing the magnetic field in the working volume (8) of the main field magnet (1) of a magnetic resonance apparatus uses ferromagnetic homogenizing elements (6) which are mounted at predetermined positions (9) on one or more support bodies (5), wherein in a first measuring step, the profile of the magnetic field is determined through measurements and in a first calculation step, occupation by homogenizing elements (6) at the predetermined positions (9;29) is calculated such that the calculated overall field, i.e.

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: An RF coil which is a coil array using three pieces or more of coils, including three pieces of coils 1, 2 and 3 or more arrayed proximately to each other, coil intermediary connecting capacitors 4, 5 and 6 respectively interposed in the coils, parallel connection lines 10 through 13 for connecting the coil intermediary connecting capacitors 4, 5 and 6 in parallel and neutralizing capacitors 14 through 17 interposed in the parallel connection lines 10 through 13 with an object of dispensing with mutual interference among the coils without overlapping the adjacent coils, in which by transmitted voltage transmitted from both ends of the coil intermediary connecting capacitor (4) of the one coil (1)to both ends of the coil intermediary connecting capacitors (5, 6)of the other coils (2, 3)via the parallel connection lines (10 through 13)and the neutralizing capacitors (14 through 17), induced voltage generated by the one coil (1) across the both ends of the coil intermediary connecting capacitors (5, 6)of the oth

Abstract: Magnet assembly for use in medical magnetic resonance imaging includes means for increasing flux generation in the gap region to provide the capability of scanning smaller volume regions of a patient at increased levels of scanning resolution. The means for increasing flux generation is mechanical or electromagnetic, is coupled to each of the polar regions and maintains the gap region sufficiently large and unobstructed to allow for access to the patient by several persons during scanning. Tapered outer walls of the polar region proximate the gap region further enhance accessibility to the patient during scanning.