Patents by Inventor Gordon D. DeMeester

Gordon D. DeMeester has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6479999
    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.
    Type: Grant
    Filed: June 5, 2001
    Date of Patent: November 12, 2002
    Assignee: Koninklijke Philips Electronics N.V.
    Inventors: Gordon D. DeMeester, Michael A. Morich, Shmaryu M. Shvartsman
  • Publication number: 20020149365
    Abstract: A pair of quadrature radio frequency coils (32, 34) disposed adjacent an imaging region (10) are typically loaded differently due to factors such as subject geometry, subject mass, and a relative distance from the subject. A tip angle adjustment circuit (50) monitors a combined tip angle adjacent a mid-plane of the examination region, such as by analyzing delivered and reflected power to each of the coils. An adjustment circuit (54) adjusts relative RF power or amplitude to produce a selected, combined tip angle in the examination region.
    Type: Application
    Filed: April 11, 2001
    Publication date: October 17, 2002
    Applicant: MARCONI MEDICAL SYSTEMS, INC.
    Inventors: Gordon D. DeMeester, Michael Burl, Michael A. Morich
  • Patent number: 6448770
    Abstract: A method of magnetic resonance imaging includes supporting a subject in an examination region of an MRI scanner(A). An MRI pulse sequence is applied to produce a detectable magnetic resonance signal (100) in a selected region of the subject. The magnetic resonance signal (100) includes a plurality of echos (102a-h) which are received. The plurality of received echos (102a-h) are subjected to a controllable gain factor such that at least two echos are subjected to different gain factors. In this manner, for example, a multi-contrast acquisition and imaging experiment may be achieved with each set of acquired echos and/or each image having a separately optimized (e.g., optimized for SNR considerations) gain factor individually selected and/or set therefor.
    Type: Grant
    Filed: March 30, 2000
    Date of Patent: September 10, 2002
    Assignee: Koninklijke Philips Electronics, N.V.
    Inventors: Kecheng Liu, Gordon D. DeMeester, Michael Burl
  • Patent number: 6441615
    Abstract: A crossed-ladder RF coil assembly (48) is employed for quadrature excitation and/or reception in an open or vertical field magnetic resonance apparatus. The RF coil assembly (48, 70, 90) includes a pair of coil assemblies (50, 52; 70, 72; 100, 102) which are disposed in a parallel relationship. Coil arrays (50, 52; 100, 102) include at least two ladder RF coils (501, 502, 503; 521, 522, 523; 1001 . . . , 1008; 1021, . . . , 1028) which are disposed in an overlapping relationship and are rotated by 90° relative to one another. Each ladder RF coil of one coil array is rotated by 90° relative to adjoining ladder coils and each corresponding ladder RF coil of the other coil array. The crossed-ladder RF coil assembly provides better B1 field uniformity and elongated anatomical coverage for spine and neck imaging. In addition, the RF coil assembly reduces noise from the body at higher fields in vertical field magnetic resonance systems.
    Type: Grant
    Filed: December 28, 1999
    Date of Patent: August 27, 2002
    Assignee: Koninklijke Philips Electronics, NV
    Inventors: Hiroyuki Fujita, Gordon D. DeMeester, Michael A. Morich
  • Patent number: 6404199
    Abstract: A quadrature RF coil assembly (48) is employed for quadrature excitation and/or reception in an open or vertical field magnetic resonance apparatus. The quadrature RF coil (48) includes a plurality of parallel rung elements (70, 72, 74, 76, 78). A pair of electrical conductive end segments (80, 82) connect the plurality of rung elements. Capacitive elements (CV, CA) interrupt a central rung element and the end segments. Preferably, the capacitive elements (CV, CA) are arranged in a high-pass configuration such that the two highest resonant modes, an odd mode (90) and an even mode (92), are tuned to have peak responsivity to a common imaging frequency. The odd mode (90) is responsive to magnetic fields which are normal to the coil (48), while the even mode is responsive to magnetic fields which are parallel to the coil (48) and perpendicular to the main magnetic field.
    Type: Grant
    Filed: December 28, 1999
    Date of Patent: June 11, 2002
    Assignee: Philips Medical Systems (Cleveland), Inc.
    Inventors: Hiroyuki Fujita, Gordon D. DeMeester
  • Patent number: 6316941
    Abstract: A tunable radio frequency birdcage coil (30) is oriented vertically in a bore-type magnetic resonance apparatus. The birdcage coil (30) includes a pair of end rings (60, 62) disposed in parallel planes along a coil axis which is orthogonal to the main magnetic field. A plurality of rungs (64) electrically interconnect the end rings (60, 62) to form a generally cylindrical volume. The end rings (60, 62) and rungs (64) are mounted on a hinged (68) dielectric former (66). Conductive connectors (70) releasably fasten the end rings (60, 62) so that the coil (30) may be opened and closed to receive a portion of a subject to be examined. A conductive loop (80) is inductively coupled and positioned parallel to the end rings (60, 62). The conductive loop (80) is slidably adjustable along the coil axis for matching and tuning end-ring modes of the coil. The coil is oriented to provide a subject disposed therein with an open view for fMRI applications.
    Type: Grant
    Filed: February 24, 2000
    Date of Patent: November 13, 2001
    Assignee: Marconi Medical Systems, Inc.
    Inventors: Hiroyuki Fujita, Gordon D. DeMeester, William O. Braum
  • Patent number: 6218838
    Abstract: A pair of annular magnets (10) generate a vertical magnetic flux field through an imaging volume (12). The flux is focused by a pair of Rose rings (26) of high cobalt steel. A high order shim set includes a plurality of permanently magnetized or magnetized iron rings (32a, 32b, 32c, 32d) which cooperatively interact with the magnet assembly to optimize the homogeneity of the magnetic flux through the imaging volume. One of the permanent magnetic rings (32d), is mounted with an opposite polarity relative to the others. The magnetized rings are mounted in a non-ferrous, electrically insulating support structure (34) such that gradient coils (50) can be positioned behind the permanent magnet rings. A flux return path (14, 16, 18, 20, 22, 24) provides a low flux resistant path from adjacent the Rose ring at one side of the imaging volume remotely around the imaging volume to a position adjacent the Rose ring at the other side of the imaging volume.
    Type: Grant
    Filed: August 28, 1998
    Date of Patent: April 17, 2001
    Assignee: Picker International, Inc.
    Inventors: John V. M. McGinley, Ian R. Young, Gordon D. DeMeester, Ilmari Kinanen
  • Patent number: 6208144
    Abstract: A region of interest of a subject (20) on a subject support (18) is positioned above a ferrous pedestal (16, 116) that is supported on a ferrous floor yoke portion (76, 176). A lower imaging coil assembly (50) including a lower gradient coil (52), a radio frequency coil (54), and a lower pole piece (58) are disposed between the pedestal and a region of interest of the subject. An upper imaging coil assembly (40) including an annular gradient coil (42, 142) and an upper annular pole piece (44, 144) is supported from a ceiling ferrous yoke member (74, 174). The upper imaging coil assembly is supported by supports (70, 170) which are moved by drives (72, 78, 172) to raise and lower the upper imaging coil assembly. A laser gauging system (80, 180) gauges the position of the upper imaging coil assembly such that, with a control circuit (82), the upper imaging coil assembly is accurately repositioned at preselected imaging positions.
    Type: Grant
    Filed: May 18, 1999
    Date of Patent: March 27, 2001
    Assignee: Picker International, Inc.
    Inventors: John V. M. McGinley, Ian R. Young, Gordon D. DeMeester
  • Patent number: 6147495
    Abstract: A magnetic resonance imaging scanner includes a pair of opposing pole pieces (20, 20') disposed symmetrically about an imaging volume (24) facing one another. The pair of opposing pole pieces (20, 20') includes a first ferrous pole piece (20) which has a front side (22) facing the imaging volume (24) and a back side (28). Also included is a second ferrous pole piece (20') which also has a front side (22) facing the imaging volume (24) and a back side (28). A magnetic flux return path (30) extends, remotely from the imaging volume (24), between a point adjacent the back side 28 of the first pole piece (20) and a point adjacent the back side 28' of the second pole piece (20)'. A source of magnetic flux generates a magnetic flux through the imaging volume (24), the pair of opposing pole pieces (20, 20'), and the magnetic flux return path (30). An array of annular hoops (40) and (40') are integrated with the pair of opposing pole pieces (20, 20') for homogenizing the magnetic flux through the imaging volume (24).
    Type: Grant
    Filed: August 28, 1998
    Date of Patent: November 14, 2000
    Assignee: Picker International, Inc.
    Inventors: Gordon D. DeMeester, John V. M. McGinley, Ian R. Young
  • Patent number: 6104192
    Abstract: A magnetic resonance imaging suite is sheathed with plates (32, 34, 36) of iron or other ferrous material. The plates define projections (42, 44, 54, 54', 68) in alignment with each other on opposite ceiling and floor or wall surfaces. A pair of magnetic pole pieces (10, 10'; 50, 50'; 60, 60') are surrounded by superconducting electromagnetic coils (12, 12'; 52, 52'; 62, 62'). The pole pieces are positioned between the ferrous plates in axial alignment. When current flows through the electromagnetic coils, magnetic flux flows between the pole pieces. The ferrous wall sheathing or other ferrous constructions define a flux return path. The pole pieces are magnetically attracted toward each other and are each magnetically mirrored in and attracted toward the adjacent ferrous flux return path.
    Type: Grant
    Filed: May 4, 1999
    Date of Patent: August 15, 2000
    Assignee: Picker Nordstar Corporation
    Inventors: Gosta Jakob Ehnholm, Ilmari Kinanen, Robert G. Gylling, Ian R. Young, Gordon D. DeMeester
  • Patent number: 6100695
    Abstract: A localized shim coil (34) for use in a magnetic resonance imaging system includes a plurality of conductive elements (22a-d). The plurality of conductive elements (62a-d) are connected to a current source (64). The plurality of conductive elements (62a-d) are arranged adjacent to a localized region of a subject being imaged such that current flowing through the conductive elements generates a localized magnetic field. A plurality of series connected choke and resister pairs (66a-d) and (68a-d), respectively, are connected to the plurality of conductive elements (62a-d). The chokes (66a-d) present high impedance to currents having frequencies substantially the same as a resonant frequency of the magnetic resonance imaging system. The resisters (68a-d) balance the current flowing through each conductive element (62a-d).
    Type: Grant
    Filed: December 6, 1999
    Date of Patent: August 8, 2000
    Assignee: Picker International, Inc.
    Inventors: Gordon D. DeMeester, Michael A. Morich
  • Patent number: 6097187
    Abstract: Primary superconducting coils (50) generate a magnetic field through an examination region (10). Stabilizing coils (70) are magnetically coupled with the magnetic field generated by the primary coils. A primary persistence switch (60) and a stabilizing coils persistence switch (72) are opened when the primary coils are connected to a current source (62) to ramp-up the magnetic field. The persistence switches are closed, disconnecting the primary coils from the current source and connecting the primary coils and the stabilizing coils into closed loops. As the magnetic flux generated by the primary coils fluctuates as the primary coils stabilize, the changing flux induces currents in the stabilizing coils. The currents induced in the stabilizing coils generate an offsetting magnetic flux such that the net magnetic flux generated by the primary and stabilizing coils is held constant.
    Type: Grant
    Filed: August 21, 1997
    Date of Patent: August 1, 2000
    Assignee: Picker International, Inc.
    Inventors: Vishnu Srivastava, Gordon D. DeMeester, Michael A. Morich
  • Patent number: 6029081
    Abstract: A magnetic resonance imaging apparatus (10) includes a couch (54) for supporting a region of interest of a subject (44) being examined in an examination region. A main magnet for generating a substantially uniform temporally constant main magnetic field through the examination region includes a stationary pole piece (24), a movable pole piece (22), a ferrous flux return path (26), and a magnetic flux generator that selectively generates magnetic flux that flows between the pole pieces (22, 24) through the examination region and through the ferrous flux return path (26) which connects the pole pieces (22, 24). The stationary pole piece (24) is arranged adjacent a first side of the examination region.
    Type: Grant
    Filed: March 19, 1998
    Date of Patent: February 22, 2000
    Assignee: Picker International, Inc.
    Inventors: Gordon D. DeMeester, Ian R. Young
  • Patent number: 6023167
    Abstract: A localized shim coil (34) for use in a magnetic resonance imaging system includes a plurality of conductive elements (22a-d). The plurality of conductive elements (62a-d) are connected to a current source (64). The plurality of conductive elements (62a-d) are arranged adjacent to a localized region of a subject being imaged such that current flowing through the conductive elements generates a localized magnetic field. A plurality of series connected choke and resister pairs (66a-d) and (68a-d), respectively, are connected to the plurality of conductive elements (62a-d). The chokes (66a-d) present high impedance to currents having frequencies substantially the same as a resonant frequency of the magnetic resonance imaging system. The resisters (68a-d) balance the current flowing through each conductive element (62a-d).
    Type: Grant
    Filed: January 26, 1998
    Date of Patent: February 8, 2000
    Assignee: Picker International, Inc.
    Inventors: Gordon D. DeMeester, Michael A. Morich
  • Patent number: 6011394
    Abstract: A superconducting magnetic imaging apparatus includes a vacuum vessel (16) having a central helium reservoir (20) in which superconducting magnetic coil windings (12) are maintained at a superconducting temperature. The vacuum vessel defines an internal bore (22) within which a self-shielded gradient coil assembly (26) and an RF coil (30) are received. The self-shielded coil assembly includes a single former (50) which defines an imaging region (14) within which an imaged portion of a subject is received. Primary x, y, and z-gradient coils (72-76) are positioned over an RF ground screen (70) that is bonded to the former (50). A number of comb-like spacers (84) extend from the former to supporting shield x, y, and z-gradient coils (110-114). The comb-like spacers define passages between the primary and secondary gradient coils which receive inner and outer cooling tubes (90, 92) and shim tray molds (108). The fully assembled gradient coil assembly is potted to form a unitary structure in a single potting step.
    Type: Grant
    Filed: August 7, 1997
    Date of Patent: January 4, 2000
    Assignee: Picker International, Inc.
    Inventors: Labros S. Petropoulos, Clarence E. Payton, Michael A. Morich, Gordon D. DeMeester
  • Patent number: 5923169
    Abstract: A magnetic resonance imaging suite is sheathed with plates (32, 34, 36) of iron or other ferrous material. The plates define projections (42, 44, 54, 54', 68) in alignment with each other on opposite ceiling and floor or wall surfaces. A pair of magnetic pole pieces (10, 10'; 50, 50'; 60, 60') are surrounded by superconducting electromagnetic coils (12, 12'; 52, 52'; 62, 62'). The pole pieces are positioned between the ferrous plates in axial alignment. When current flows through the electromagnetic coils, magnetic flux flows between the pole pieces. The ferrous wall sheathing or other ferrous constructions define a flux return path. The pole pieces are magnetically attracted toward each other and are each magnetically mirrored in and attracted toward the adjacent ferrous flux return path.
    Type: Grant
    Filed: November 18, 1997
    Date of Patent: July 13, 1999
    Assignee: Picker Nordstar Corporation
    Inventors: Gosta Jakob Ehnholm, Ilmari Kinanen, Robert G. Gylling, Ian R. Young, Gordon D. DeMeester
  • Patent number: 5825185
    Abstract: A transmitter (24) and gradient amplifiers (20) transmit radio frequency excitation and other pulses to induce magnetic resonance in selected magnetic dipoles and cause the magnetic resonance to be focused into a series of echoes (66) at each of a plurality of preselected echo positions following each excitation. A receiver (38) converts each echo into a data line. Calibration data lines having a close to zero phase-encoding are collected and used to generate correction parameters (102) for each of the echo positions. These parameters include relative echo center positions (96) and unitary complex correction vectors (106). The calibration data lines for each of the preselected positions are one-dimensionally Fourier transformed (82) and multiplied (90) by the same complex conjugate reference echo (80). These data lines are then inverse Fourier transformed (92) to generate an auxiliary data array (94).
    Type: Grant
    Filed: November 27, 1996
    Date of Patent: October 20, 1998
    Assignee: Picker International, Inc.
    Inventors: Haiying Liu, Francis H. Bearden, Gordon D. DeMeester
  • Patent number: 5786695
    Abstract: The magnetic field assembly of a magnetic resonance imaging device includes an annular superconducting magnet (10) which is mounted within a toroidal vacuum vessel (24). Two cylindrical members (26, 46) define an annular gap (58). A shim set (60) for shimming the uniformity of the magnetic field is mounted in the gap (58). The shim set includes a plurality of shim trays (62), each of which defines a plurality of shim receiving pockets (64). A bottom wall (81) of each pocket is spaced from the cylindrical member (26) by side walls (76) and feet (78) to minimized heat flow. Shim tray covers (68) have flanges (90) and narrow contact surfaces (94) which are cammed against surfaces (61) of spacers (56) to press the cover on the tray and the tray feet against the cylinder (26) while minimizing heat flow through the spacers to the shims.
    Type: Grant
    Filed: March 21, 1997
    Date of Patent: July 28, 1998
    Assignee: Picker International, Inc.
    Inventors: William H. Amor, Jerome S. Alden, Gordon D. DeMeester, James L. Gruden, Junxiao Ling
  • Patent number: 5742163
    Abstract: A sequence control (40) causes a transmitter (24) and gradient amplifiers (20) to transmit radio frequency excitation and other pulses to induce magnetic resonance in selected dipoles and cause the magnetic resonance to be focused into a series of echoes in each of a plurality of data collection intervals following each excitation. A receiver (38) converts each echo into a data line. Calibration data lines having a close to zero phase-encoding are collected during each of the data collection intervals. The calibration data lines in each data collection interval are zero-filled (86) to generate a complete data set and Fourier transformed (88) into a series of low resolution complex images (90.sub.1, 90.sub.2, . . . 90.sub.n), each corresponding to one of the data collection intervals. The low resolution images are normalized (92) and their complex conjugates taken (94). Imaging data lines are sorted by a data collection interval and zero-filled (104) to create full data sets.
    Type: Grant
    Filed: April 26, 1996
    Date of Patent: April 21, 1998
    Assignee: Picker International, Inc.
    Inventors: Haiying Liu, Gordon D. DeMeester, James M. McNally
  • Patent number: 5675305
    Abstract: A ferromagnetic flux path (20) extends between pole pieces (30,32). A superconducting coil (62) in series with a persistence switch (64) encircles the flux path. A pair of resistive coils (50,52) are disposed one at each pole piece. The resistive coils are overdriven near to the point of thermal failure to produce a 0.5 T or other preselected field strength in a gap between the pole pieces. The persistence switch is closed to stabilize and hold the flux through the superconducting coil. The resistive magnets are ramped down or shut off. During imaging, a smaller amount of current is directed to the resistive coils to supplement and focus the magnetic field from the superconducting coil through the gap between the poles. In this manner, high strength magnetic fields are generated in the gap using a relatively inexpensive combination of resistive and superconducting coils.
    Type: Grant
    Filed: July 17, 1996
    Date of Patent: October 7, 1997
    Assignee: Picker International, Inc.
    Inventors: Gordon D. DeMeester, Michael A. Morich