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 quadrature coil suitable for use with an open frame MRI system provides crossing pairs of arrays of parallel conductor elements, respectively. Compact configuration is provided through use of an isolating circuit for incorporating parasitic capacitances at the resonance frequency of the coil into a blocking parallel resonance. Termination of the parallel conductor elements may be accomplished by equal impedance node connectors formed from branching pairs of conductors or a triangular least resistance connection form. RF shields are provided by pairs of conductive sheets containing eddy current reducing slots aligned with the parallel conductors elements of the coil.

Abstract: A magnetic resonance image receiving coil includes a first balloon having a longitudinal axis. An internal surface of the first balloon defines an internal inflatable chamber. A second balloon has a longitudinal axis. The second balloon is disposed about the first balloon. A plurality of longitudinally extending grooves are disposed in one of an external surface of the first balloon and the internal surface of the second balloon. A first wire is disposed in at least one of the grooves. A second wire is disposed in at least a second one of the grooves. Each of the first wire and the second wire is adapted to be electrically connected to an MRI apparatus. In accordance with an alternate embodiment, the first and second wires are disposed in grooves in a sheath which is disposed between the first and second balloons. In accordance with a further alternate embodiment, the first and second wires are disposed in guide tubes that are connected to the external surface of a balloon.

Abstract: In an MR tomography system and a method for operating an MR tomography system for the purpose of executing both fast and conventional measuring sequences with high image resolution without triggering stimulations in a living subject and with a high degree of freedom in the selection of imaging regions, a gradient coil is provided with at least two independently controllable potions, so that it is possible to set up gradient fields for a first imaging subregion and for a second imaging subregion that is not a subset of the first region and does not contain it, as well as an aggregate imaging region that contains at least the first and second imaging regions.

Abstract: A restraining apparatus and method for limiting motion on the macro and micro scale during MRI and CT scans, by providing a custom fit, while also improving patient comfort. The restraining apparatus includes a disposable component, including castable and expandable sleeves used to fix the patient into a coil. The castable sleeve encircles the limb of a patient, and is filled with a quickly casting material. The cast material is patient compatible and preferably designed to augment imaging. The resulting cast is MRI compatible, safe and rapid setting, which will decrease the time to set up a patient for scanning, thereby further improving MRI productivity. The expandable sleeve encircles the castable sleeve and is inflatable such that the expandable sleeve conforms to the inner dimensions of a particular MRI coil, CT scanner, or other imaging device. Alternatively, the apparatus includes a castable sleeve for casting around a flex/wrap or surface coil.

Abstract: A radio frequency coil for a magnetic resonance image apparatus includes a first support frame provided with a first coil, a second support frame opposing the first support frame and provided with a second coil, a gap adjuster for adjusting a gap between the first and second support frames according to the size of a specimen, and a frequency sustainer for sustaining a resonance frequency set according to change of the gap. The magnetic resonance image apparatus adopting the radio frequency coil alleviates impatience of a patient, to thereby enable rejection of patients with respect to the magnetic resonance image apparatus to be solved. Also, the magnetic resonance image apparatus enables a patient to be taken a photograph and simultaneously operated. In addition, the second support frame can be moved to reduce a gap between the first and second support frames to thereby greatly improve quality of an image.

Abstract: A magnetic resonance method for forming a fast dynamic image from a plurality of signals of an RF probe is described. The RF probe is moved relative to an object to be imaged so as to acquire at least two adjacent Fields-of-View (FOV) which are reconstructed so as to form an image of a region of interest which includes both FOVs. The object to be imaged is scanned by a moving RF antenna. Furthermore, the first FOV is centered at the initial probe position and after each subsequent scan the position of the imaging field within the actual FOV is determined. From that data the next position of the RF probe relative to the object is computed and, if the imaging field runs out of the actual FOV, the RF antenna is moved to the estimated next position of the RF probe so that the subsequent FOV is centered again at the RF probe position. A composite image is then generated from the successive images of the various adjacent FOVs.

Abstract: An RF coil array arrangement for enhanced magnetic resonance imaging of the breast or spine regions of prone and supine patients within a vertically oriented B0 field is disclosed. Several RF coil array embodiments are disclosed that provide for both generating a nuclei nutation field pulse and acquiring nuclear magnetic resonance signals when functioning in an MRI apparatus environment that employs a vertical main magnetic field. A coil array may include one or more RF coils that are intended to be oriented such that their primary B field direction(s) are perpendicular to the vertical magnetic field of the MRI apparatus. Each coil array may further include one or more single loop or solenoidal coil(s) that are oriented having their central or longitudinal axis aligned parallel to the vertical main magnetic field so as to make advantageous use of non-axial field components associated with the coil(s) to further generate and receive desired NMR signal components.

Abstract: A radiotherapy machine beam treats a region of a subject while the region and volumes abutting the region are imaged by a magnetic resonance imaging system. The beam and an excitation coil assembly of the imaging system are arranged so the beam is not incident on the coil assembly and magnetic fields derived from the coil assembly do not interact with the beam. The excitation coil assembly includes two spaced winding segments for producing a main DC magnetic field; the segments are located on opposite sides of the region. In one embodiment, wherein the excitation coil assembly is mounted independently of movement of an axis of the beam, the winding segments have a common axis generally aligned with an axis about which the beam axis turns. A treatment couch for the subject fits within aligned central openings of the winding segments. The coil produces main magnetic field lines that extend generally in the same direction as the axis about which the beam turns.

Abstract: A coil interface for coupling a phased array magnetic resonance imaging coil to a magnetic resonance imaging system. The coil interface includes a plurality of signal inputs and a plurality of output ports. Each of the output ports is associated with a receiver in the magnetic resonance imaging system. The coil interface also includes an interface circuit. The interface circuit selectively couples at least two of the signal inputs to at least one of the plurality of input ports. Where the coil is a quadrature phased array coil, a preferred embodiment allows the two quadrature signals to be acquired as a single signal, precombined at the RF level within the coil interface, or as two separate RF signals by two of the receivers of the magnetic resonance imaging system hardware.

Abstract: A compact magnet and an RF probe which can accommodate a human extremity such as a heel are used to construct a compact MRI system for diagnosis and follow-up of osteoporosis and other diseases. Methods for measuring and calculating proton density in inhomogeneous static magnetic field, magnetic field gradients, and RF magnetic field are provided using 2D spin-echo image acquisitions with external reference materials and image analyses. The measured proton density of bone marrow is used for computation of trabecular bone volume fraction, which can be used for diagnosis of osteoporosis and other diseases.

Abstract: A magnetic resonance imaging system is provided with a system of emission antennae (13), for example, emission coils, for generating RF excitation pulses. Such RF excitation pulses generate magnetic resonance signals from an object to be examined. The system of emission antennae has a spatially inhomogeneous emission profile. The inhomogeneous emission profile is used for the partial spatial encoding of the magnetic resonance signals in addition to the encoding on the basis of magnetic gradient fields. The magnetic resonance image is reconstructed on the basis of the inhomogeneous emission profile.

Abstract: An inherently de-coupled sandwiched solenoidal array coil (SSAC) is disclosed for use in receiving nuclear magnetic resonance (NMR) radio frequency (RF) signals in both horizontal and vertical-field magnetic resonance imaging (MRI) systems. In its most basic configuration, the SSAC comprises two coaxial RF receive coils. The first coil of the array has two solenoidal (or loop) sections that are separated from one another along a common axis. The two sections are electrically connected in series but the conductors in each section are wound in opposite directions so that a current through the coil sets up a magnetic field of opposite polarity in each section. The second coil of the SSAC is disposed (“sandwiched”) between the two separated solenoidal sections of the first coil in a region where the combined opposing magnetic fields cancel to become a null.

Abstract: A medical examination system, particularly a magnetic resonance system, has a host computer unit, a control computer unit and an image computer unit. The control computer unit is realized in the form of at least one insert card that is arranged in a commercially obtainable personal computer that contains the host computer unit.

Abstract: In order to mitigate the feeling of confinement experienced by a subject (patient) and improve the S/N ratio of an MRI coil when used as a head coil, there is provided an MRI coil 10 comprising a pair of opposing coils 1 and 2 whose coil surfaces face each other with an imaging space interposed, and a quadrature coil 3 which has a coil surface orthogonal to the coil surfaces of the opposing coils 1 and 2 and surrounds the imaging space. When the MRI coil 10 is used as a head coil, the quadrature coil 3 is fitted over the eyes of a subject H, and the opposing coils 1 and 2 are positioned near the ears of the subject H.

Abstract: Objects of this invention include provision of magnetic resonance (MR) imaging methods, MR apparatus, and radio-frequency (RF) receiving coil devices permitting interactive MR examination of a patient. In particular, this invention includes means for generating MR images by a moveable RF coil which can be moved across a patient during an MR examination. The MR apparatus includes a position detection system which detects the current position and orientation of the moveable RF coil. The coil can be hand held for manual movement or can be attached to mechanical manipulators for controlled movement. The imaging methods determine and generate magnetic gradient and RF pulse sequences to excite nuclear magnetization in a 3D region determined with respect to the current 3D position and 3D orientation of the moveable RF coil. The invention also includes moveable RF coils for receiving and transmitting which are configured and sized for convenient manipulation by an operator.

Abstract: A transportable magnetic resonance imaging apparatus, said apparatus comprising a transportable platform, provided with a casing made of ferromagnetic metal, and a magnetic resonance imaging system mounted onto said transportable platform, said magnetic resonance imaging system comprising a front end and a back end, the front end comprising a magnetic structure for the provision of a magnetic field, at least two gradient coils, RF transmit coil, and RF receive coil, and the back end comprising a host computer as a central processing unit, at least two gradient amplifiers, RF amplifier, MRI spectrometer, MRI controller and display unit, wherein said apparatus is provided with a positioning assembly for moving and positioning said magnetic structure between a first position and a second position, said first position being such that a patient's body part is positioned between said magnetic field, and said second position being such that said pair of magnets is positioned inside said casing, when not in use,

Abstract: A magnetic resonance (MR) imaging apparatus and technique exploits spatial information inherent in a surface coil array to increase MR image acquisition speed, resolution and/or field of view. Magnetic resonance response signals are acquired simultaneously in the component coils of the array and, using an autocalibration procedure, are formed into two or more signals to fill a corresponding number of lines in the signal measurement data matrix. In a Fourier embodiment, lines of the k-space matrix required for image production are formed using a set of separate, preferably linear combinations of the component coil signals to substitute for spatial modulations normally produced by phase encoding gradients. One or a few additional gradients are applied to acquire autocalibration (ACS) signals extending elsewhere in the data space, and the measured signals are fitted to the ACS signals to develop weights or coefficients for filling additional lines of the matrix from each measurement set.

Abstract: A birdcage coil comprises a number of elements in birdcage geometry wherein the density of elements is such that the contribution to the total inductance from the mutual inductance of said legs exceeds 45% by conventional model calculation. To accommodate the desired density of elements, necessary capacitances are obtained from compact structures such as inter-digitated patterns which may be oriented axially or between elements, or from arrangements of element portions on opposite sides of a cylindrical substrate.

Abstract: The present invention relates to a restraining assembly used in neuroimaging of animals in magnetic resonance imaging (MRI) systems. The body of the animal under study is secured within a tube with a head holder to reduce motion artifacts, particularly when the animal is awake. The tube is placed in the bore of the MRI system to conduct imaging procedures with a radio frequency coil adjacent to the animals' head.

Abstract: This invention relates to a method for MR imaging using a moveable RF receiving coil assembly that is swept over the region of interest to be imaged during the imaging protocol.

Abstract: In order to mitigate the feeling of confinement experienced by a subject (patient) and improve the SIN ratio of an MRI coil when used as a head coil, there is provided an MRI coil 10 comprising a pair of opposing coils 1 and 2 whose coil surfaces face each other with an imaging space interposed, and a quadrature coil 3 which has a coil surface orthogonal to the coil surfaces of the opposing coils 1 and 2 and surrounds the imaging space. When the MRI coil 10 is used as a head coil, the quadrature coil 3 is fitted over the eyes of a subject H, and the opposing coils 1 and 2 are positioned near the ears of the subject H.

Abstract: In a method for the operation of a diagnostic magnetic resonance apparatus, a number of local antennas are arranged at known positions with respect to a patient support. Before an activation of at least one of the local antennas for imaging, at least one characteristic property of each local antenna is presented in an overview image of a patient on the patient support. Based on this displayed characteristic property, the optimum local antenna or antennas best suited for obtaining a desired image is/are activated for obtaining image data.

Abstract: The present invention comprises a whole body RF coil system for use with an open magnetic resonance (MR) imaging system. The RF coil system comprises first and second quadrature RF coil sets positioned on opposing sides of an imaging volume. Each RF coil set comprises similarly-structured, multiple RF coils. Each quadrature RF coil comprises a first and second plurality of primary path conductor segments, and first and second return path conductors, symmetrically disposed about a centerline at specified distances. The first and second plurality of primary path conductor segments are positioned in a first plane that is substantially spaced apart from a second plane, further from the imaging volume, containing the first and second return path conductors. The conductors within each of the first and second set of primary path conductor segments are adapted to have a predetermined current amplitude ratio.

Abstract: In order to mitigate the feeling of confinement experienced by a subject (patient) and improve the S/N ratio of an MRI coil when used as a head coil, there is provided an MRI coil 10 comprising a pair of opposing coils 1 and 2 whose coil surfaces face each other with an imaging space interposed, and a quadrature coil 3 which has a coil surface orthogonal to the coil surfaces of the opposing coils 1 and 2 and surrounds the imaging space. When the MRI coil 10 is used as a head coil, the quadrature coil 3 is fitted over the eyes of a subject H, and the opposing coils 1 and 2 are positioned near the ears of the subject H.

Abstract: The invention relates to a method of navigating a magnetic object (11) within an object (1) which is exposed to a magnetic field, as well as to a magnetic resonance device in which this method can be carried out. The method according to the invention is particularly suitable for navigating a catheter or a flexible endoscope within the body of a patient. The magnetic object (11), preferably being provided in or on such a medical instrument (10), has a controllable magnetic moment for this purpose and the direction of movement of the object is determined by control of the magnetic moment. In the case of a magnetic resonance device whose static magnetic field is used, the object (11) is preferably includes as a coil system.

Abstract: A diagnostic imaging apparatus such as a magnetic resonance imaging (MRI) device includes a gradient coil assembly (34) and an RF coil (36) disposed proximate pole faces (30, 32). An interventional head coil assembly (40) includes a base (90), a head frame housing (96) including at least one first conductor (130) associated therewith, a first mount (94) that connects the head frame housing (96) to the base (90), a bridge housing (98) including at least one second conductor (142) associated therewith, and a second mount (100) that connects the bridge housing (98) to the head frame housing (96) thereby coupling the at least one first conductor (130) to the at least one second conductor (142) to form a surface coil for use in imaging an object attached to the head frame housing (96).

Abstract: A radiotherapy machine beam treats a region of a subject while the region and volumes abutting the region are imaged by a magnetic resonance imaging system. The beam and an excitation coil assembly of the imaging system are arranged so the beam is not incident on the coil assembly and magnetic fields derived from the coil assembly do not interact with the beam. The excitation coil assembly includes two spaced winding segments for producing a main DC magnetic field; the segments are located on opposite sides of the region. In one embodiment, wherein the excitation coil assembly is mounted independently of movement of an axis of the beam, the winding segments have a common axis generally aligned with an axis about which the beam axis turns. A treatment couch for the subject fits within aligned central openings of the winding segments. The coil produces main magnetic field lines that extend generally in the same direction as the axis about which the beam turns.

Abstract: An RF quadrature detection coil for interventional MRI comprises two nested orthogonal coils having generally rectangular shape in profile, each coil providing one “channel” of signal for quadrature detection. Each rectangular coil has two conductor windings and a common side in which the two conductors along that side are displaced apart in a common plane orthogonal to the plane of the coil to form a circular opening. The two individual coils are configured such that their rectangular conductor winding portions lie in planes perpendicular to each other but their arcuate conductor winding portions coincide in the same plane. Four paralleled conductors are arranged around the shared circular opening while two paralleled conductors form the three sides of the rectangular portion of each individual coil.

Abstract: A sweep generator 230 applies a range of frequencies to an rf coil 140 to detect the resonant frequency of a field generated by a magnet 125a,b. A frequency to current converter 220 applies an auxiliary magnetic field to tune an MRI apparatus to the resonant frequency of the rf coil. A flexible coil of one turn (300) or two or more turns (500) has a plurality of segments (301-307; 501-513). One of the belt has a contact k0, (k0′), which is electrically connectable to one or more contacts k1, (k1′), k2, (k2′), etc. located between the ends of the segments. For each connection to successive contacts, the length of the coil and its inductance increases by the added impedance DLij between contacts ki and kj. That increase of inductance is nullified by capacitors DCsij located between segments.

Abstract: A magnetic imaging apparatus generates a main magnetic field longitudinally through an image region and excites magnetic resonance in selected nuclei in a patient or subject disposed in the image area. The resonating nuclei generate radio frequency magnetic resonance signals which are received by a quadrature highpass ladder surface coil (D). The highpass ladder coil includes a central leg 34 having a capacitive element Cv disposed symmetrically about a midpoint 44. A like number of additional legs 30, 32, 36, 38 are disposed parallel to and symmetrically on opposite side of the central leg. Side elements 40, 42 include capacitive elements CA which interconnect adjacent ends of each of the legs. The capacitive elements are disposed symmetrically about the midpoint 44 and are selected such that the coil supports at least two intrinsic resonant modes including an odd mode 50 and an even mode 52.

Abstract: A pair of RF quadrature detection coils are fitted in an open support structure that allows easy diagnostic access to all tissue areas of the human female breast when performing interventional MRI. The open structure dual coil arrangement comprises a flat base and a slightly "V"-shaped bi-planar upper section supported above the lower base section by eight narrow vertical legs. The upper bi-planar section includes two circular openings for accepting the breasts. Four of the support legs are equally spaced at 900 intervals around each breast opening and provide large side-open access areas to the breast tissues via the sides of the support structure. The "V"-shape of the upper portion of the coil support structure increases the gap clearance at both left and right sides of the support structure to further enhance access to the breasts.

Abstract: An MR imaging system with an electrically insulated coil element includes at least one first coil element which is electrically connected to an electronic unit and at least one electrically completely insulated second coil element which is magnetically coupled to the first coil element. Operative interventions in a region to be examined are possible through a free access area. The sterility that is necessary during operations is ensured by a device for shielding from germs.

Abstract: A coil assembly for use in MRI imaging includes a harness having a base. First and second arm members extend from a first side of the base and above and over the base and third and fourth arm members extend from a second side of the base and above and over the base. A first cross member extends between the first arm member and the second arm member and a second cross member extends between the third arm member and the fourth arm member. An end of the first arm member is aligned with and detachably connected to an end of the third arm member and an end of the second arm member is aligned with and detachably connected to an end of the fourth arm member. First and second coil members each extend along the harness. The first coil member may be a saddle coil and the second coil member may be a solenoid coil configured to establish a quadrature arrangement.

Abstract: In order not to nip the clothes or skin of a subject between the joining portions of coil members when a detecting coil for a magnetic resonance diagnostic apparatus is fitted around a region of the subject such as the leg or neck, the detecting coil 100 for a magnetic resonance diagnostic apparatus, which can be separated into an upper coil member 10 and a lower coil member 20 and has an annular shape when these members 10, 20 are integrally joined, is provided at the joining portions of the lower coil member 20 with guards 27, 28 of a silicone rubber having a hardness of Hs80.

Abstract: An MR coil array includes a plurality of telescopically arranged coil units, spanning the length of an extremity (e.g. a leg). The coil in each unit encircles the extremity, providing good SNR from all sides and for deep structures as well. The tapered shape of the array conforms generally to the patient anatomy, minimizing sensing distances, further enhancing SNR. A low ratio between the volume imaged and the aggregate coil conductor length further contributes to high SNR. A multiplicity of tuning capacitors makes the array relatively insensitive to detuning by differently-sized patients. Adjoining coils can be oriented to produce perpendicular magnetic fields, reducing coupling therebetween. An apparatus employing two such coil arrays allows imaging of two extremities at once.

Abstract: Magnetic resonance scanner has a radio-frequency system with transmission/reception antennas, and possibly a radio-frequency shield as well, and guides for a movable patient bed arranged in a basic field system and in a gradient system, with the electrical components of the radio-frequency system being embedded in a cylindrical, rigid carrier tube that penetrates the basic field system and the gradient system in the axial direction and which simultaneously serves as a carrier for the guides for the patient bed. The carrier tube is introducible as structural unit into the basic field and gradient system.

Abstract: A universal-tuned RF probe (8) is disclosed which covers all current nuclear MRS and MRI applications and anticipates the utilization of multiple nuclides. This probe comprises a switchable thin multi-layer coil (29, 30, 31), electronically controlled switches (11, 12), an impedance matching circuit (13-20), and a resonant frequency tuning circuit (21-28). By quick switching, all different nuclei are detected independently, therefore their performances can be optimized individually. Fast switching (of less than 10.sup.-9 seconds) allows multiple frequencies to operate simultaneously. A switchable thin multi-layer coil (29, 30, 31) is used to cover a wide range of resonant frequencies and maintain identical RF B1 magnetic fields for all the different nuclei.

Abstract: A method of designing a shielded gradient coil assemblies (22) with a flared primary coil (60) for magnetic resonance imaging systems is provided. The method includes generating a first continuous current distribution for a primary coil (60) using an inverse approach. The first continuous current distribution is confined within predetermined finite geometric boundaries of a surface defined by three dimensions and generates a magnetic gradient field across an imaging region (14). The magnetic gradient field is constrained to predetermined values at specified spatial locations within the imaging region (14). The current distribution and magnetic field are converted into a stored energy and magnetic field domain where a finite element analysis is performed to generate a second continuous current distribution for a shielding coil (62). The second continuous current distribution is confined within predetermined finite geometric boundaries of a surface surrounding the primary coil (60).

Abstract: A homogeneous field electromagnet having at least two coils in each of two regions. One region has a smaller inner radius than the other region so that the magnet is asymmetrical. The magnet has coils with a smaller radius on one side compared to the other side. This provides the benefit of allowing the magnet to be shorter for a given field of view size (compared to a uniform-radius cylindrical magnet). In a preferred embodiment the magnet is short enough so that a patient's heart can be located within the field of view (FOV) while visual access is provided to the patient's face. Specific dimensions are given for the two regions, including lengths, inner radii, and outer radii. The magnet can also include gradient coils and RF electronics for magnetic resonance imaging.

Abstract: A resonator structure including a first resonator having a first resonator loop formed by a hollow channel with conductive walls and a second resonator having a second resonator loop formed by a hollow channel with conductive walls. The first resonator loop and the second resonator loop intersect so that the first and second resonator loops are substantially shielded to prevent coupling of high frequency energy between the first and second resonator loops. The orthogonally of the resonator loops can be adjustably control in either of two orthogonal axes. A sample is placed in a space defined by the intersection of the first and second resonator loops. High frequency energy is applied to the first resonator. The angle at which the second resonator loop intersects the first resonator loop is selected to substantially decouple the first resonator from the second resonator. A detector circuit detects the high frequency energy in the second resonator loop and supplies the detected signal for subsequent analysis.

Abstract: An MR apparatus includes an MR coil system of the so-called bird cage type which operates in a degenerate mode of operation in which all resonance modes and all resonance frequencies coincide. It has been found that the individual meshes of the MR coil system are then decoupled from one another, thus enabling operation as a coil array, the individual MR signals being processed in separate processing channels so as to form MR sub-images which can be combined in a reconstruction unit so as to form an MR overall image having an improved signal-to-noise ratio.

Abstract: A magnetic resonance imaging apparatus has a gantry including various coils such as a static field coil and gradient field coils, a top board for supporting an examinee and moving the examinee into and out of an opening of the gantry, and an approximately cylindrical RF coil defining a hollow space therein. The RF coil is set to the top board, with an axis of the hollow space extending at an angle to the horizontal. The examinee's imaging site is inserted into the hollow space of the RF coil to have sectional images picked up. Since the RF coil is set to the top board with the axis of the hollow space inclined relative to the horizontal, sectional images may be picked up by using the approximately cylindrical RF coil while allowing the examinee to take a comfortable posture without enlarging the RF coil.

Abstract: A less-claustrophobic, quadrature, radio-frequency head coil (42) includes first and second broken end rings (90, 92) connected to each other in parallel by a plurality of leg conductors (94). At least two of the leg conductors are interconnected by a third arcuate conductor segment (98) axially displaced from planes of the first and second end rings to provide an opening (44) over a subject's face. The opening reduces patient claustrophobia and permits access to the patient for life-support devices or the practice of interventional medicine. The end rings have a fixed capacitance (C.sub.1, C.sub.2) between each pair of leg conductors. The fixed capacitance C.sub.1 between at least one pair of leg conductors and the fixed capacitance C.sub.2 between at least the pair of leg conductors adjacent the opening, where C.sub.2 >C.sub.1. A two-port feed (66, 68) circumferentially attached to the coil generally opposite the opening matches the individual linear modes.

Abstract: A radio frequency antenna for conducting magnetic resonance imaging studies of the breast region of a patient includes a tuned primary coil inductively coupled to two tuned secondary coils. Each secondary coil defines a region for receiving one of the breasts of the patient, and receives magnetic resonance signals emitted from each breast and the surrounding region of the patient. The primary coil can be connected to the receiving circuitry of the magnetic resonance imaging system. The magnetic resonance signals received by the secondary coils induce signals in the primary coil which are provided to the magnetic resonance imaging system for processing. The secondary coils, which preferably include two windings, each have a portion adjacent to the primary coil and a portion distanced from the primary coil.

Abstract: Acoustically controlled magnetic coils comprise first and second electrical conductors which are mechanically coupled by a block of material of defined acoustic transmission characteristics which holds the conductors a predetermined distance apart. The conductors are supplied with currents of different and variable amplitudes and different and variable relative phases both of the features being determined by the acoustic characteristics and by the geometry and predetermined distance.

Abstract: A snap-in, whole-body radio frequency coil (38) for increasing the diameter of a bore (12) of a toroidal magnetic resonance imaging apparatus includes a plurality of longitudinally extending coil elements (42) having element ends (44). The longitudinally extending coil elements are disposed on a flat, flexible, non-conductive plastic sheet (40) which is capable of being rolled and disposed concentricly in an interior diameter of the bore to form a thin-walled, bird-cage type radio frequency coil. Adjacent element ends are connected with a first capacitance C.sub.0 to resonate the coil at a certain frequency. To permit mechanically switching the resonant frequency of the coil, protruding metal contacts (60) are electrically connected to the element ends. An adjustment end ring includes separated metal pads (66) disposed on a non-conducting ring substrate (64). Adjacent metal pads are connected with second capacitances C.sub.1.

Abstract: A nuclear magnetic resonance sensing apparatus, including a magnet for inducing a static magnetic field within materials to be analyzed. The magnetic field is substantially coaxial with a longitudinal axis of the apparatus. The magnetic field is polarized substantially perpendicularly to the longitudinal axis and is symmetric about the axis. The static magnetic field has a maximum longitudinal gradient which is inversely related to a speed of motion of the apparatus along the longitudinal axis through the materials to be analyzed. The apparatus includes a transmitter for generating a radio frequency magnetic field in the materials for exciting nuclei in the materials. The radio frequency magnetic field is substantially orthogonal to the static magnetic field. The apparatus includes a receiver for detecting nuclear magnetic resonance signals from the excited nuclei in the materials. In a preferred embodiment, the magnet comprise magnetized cylinders stacked along the longitudinal axis.

Abstract: RF receiving coil device used in a magnetic resonance imaging apparatus capable of acquiring a tomographic image of an object under examination positioned in a static magnetic field along a predetermined direction including quadrature detection coils for detecting an MR signal component along a direction perpendicular to a body axis direction of the object under examination and also perpendicular to a direction of the static magnetic field, and for detecting another MR-signal component along the body axis direction.

Abstract: A gradient system for a nuclear spin resonance (NMR) tomograph with a main magnet system producing a homogeneous magnetic field directed along a z-axis inside a measuring volume, wherein the main magnet system provides access to the measuring volume along the z-axis and transversely to the z-axis, and wherein the gradient system comprises two first partial gradient systems which are located at opposite sides of a central plane perpendicular to the z-axis, across the measuring volume. At least one of the two partial gradient systems is movable between at least two positions along the z-axis. In this way, with a small constructional size and with a simple manufacturing procedure, a gradient system is obtained with high performance capability with respect to generated gradient strength for given ampere turns, high linearity of the generated gradient fields, minimum inductance and minimum electrical resistance of the conductor segments.