Patents Assigned to Picker International, Inc.
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Patent number: 6441711Abstract: A high temperature superconductor (HTSC) 5 is magnetized between drive coils 1,2 forming poles of a magnet connected by an iron yoke 9 by relative movement of a vacuum insulated cryostat 4 containing the HTSC and the magnetizing magnet, in order to magnetize a large area of HTSC using a magnet with a small region 3 of magnetizing flux. Alternatively, the HTSC 5may be contained in an evacuated region of a cryostat containing the magnetizing magnet. An interconnecting chamber allows the HTSC to be moved between an operative region and a magnetizing region without substantial loss of vacuum.Type: GrantFiled: March 21, 2001Date of Patent: August 27, 2002Assignee: Picker International, Inc.Inventor: Ian Robert Young
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Patent number: 6385478Abstract: In a magnetic resonance imaging apparatus in which excitation pulses are applied to a restricted region 5 of a magnetic resonance imaging magnet bore, in which the field is uniform, and the data samples collected are Fourier transformed to form a volumetric image of the restricted region, a motor 6 continuously moves a patient couch 3 so that a region of interest passes through the region of good field, and the data samples collected are corrected to compensate for the motion so that a volumetric image is formed of greater length than that of the restricted region.Type: GrantFiled: December 21, 1999Date of Patent: May 7, 2002Assignee: Picker International, Inc.Inventor: Joseph Vilmos Hajnal
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Patent number: 6377837Abstract: A medical instrument, for use in relation to an MR scanner, comprising body portion having mounted thereon a plurality of positioning elements each of which comprises a reservoir containing a liquid and at least two spaced tuned MR auxiliary receiver coils positioned coaxially with respect to one another and carried by the reservoir, and means for electrically connecting the said auxiliary coils to separate receiver channels of the MR scanner. Flux enhancement is used to enable the positioning elements to be rapidly located without disturbing the magnetization of the patient and thereby permit the position of the medical instrument and the image of the patient to be rapidly cycled between.Type: GrantFiled: November 21, 1997Date of Patent: April 23, 2002Assignee: Picker International, Inc.Inventors: Glyn A. Coutts, Larry Kasuboski
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Patent number: 6366092Abstract: In magnetic resonance imaging apparatus having a resistive electromagnet with a bore 6, r.f. excitation pulse substantially simultaneously excites a number of slices A to D which are phase encoded and frequency encoded in the usual way, the direction of the main field being along the bore of the electromagnet in the direction z. The receive coil consists of an array of coils 5a to 5d which view different spatial regions of the imaging volume and the outputs of which are combined in different ways in order to reduce the number of slice encoding steps in the z-direction needed to distinguish between the slices A to D. Each coil of the array 5a etc. can form part of a two dimensional array in order to reduce the number of phase encoding steps in the phase encode direction.Type: GrantFiled: December 23, 1999Date of Patent: April 2, 2002Assignee: Picker International, Inc.Inventors: Gosta J Ehnholm, Ian Robert Young
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Patent number: 6359279Abstract: A radiation detector includes slit collimator. A radiation detector receives radiation which has been received in each of the slits. The aspect ratio of the detector is approximately three, and each semiconductor radiation detector has a transverse dimension which is less than that of its respective slit. A reconstruction processor generates an image indicative of the radiation received by the detectors. The detector may be rotated about a fixed axis. Alternately, the detector may be translated in coordination with its rotation to provide a substantially square field of view.Type: GrantFiled: December 7, 1998Date of Patent: March 19, 2002Assignee: Picker International, Inc.Inventors: Daniel Gagnon, Christopher G. Matthews
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Publication number: 20020025023Abstract: A computerized tomography system includes a stationary section (A) and a rotating section electrically linked by at least one interconnecting slip ring (D). On one side the slip ring (D) is configured as a series of electrically conductive segments (20A-20H) separated by non-conductive interruptions (22A-22H). On the other side a like number of transmitters (26A-26H) is in selective electrical contact with the conductive segments (20) depending on a position of the rotating frame. Also included is a de-multiplexer (40) which takes image data from the plurality of receivers (RxA-RxH) and rearranges the image data in a determined sequence. Also shown is an angular encoder (46) for providing angular displacement signals (44) to the de-multiplexer (40) for assistance in reconstructing the data channels (30) in the determined sequence.Type: ApplicationFiled: October 15, 2001Publication date: February 28, 2002Applicant: PICKER INTERNATIONAL, INC. a New York Corporation.Inventors: Mark D. Herold, Theodore A. Resnick
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Patent number: 6340887Abstract: A black blood magnetic resonance angiogram is produced by exciting dipoles (52) and repeatedly inverting the resonance (541, 542, . . . ) to produce a series of magnetic resonance echoes (561, 562, . . . ). Early echoes (e.g., (561, . . . , 568)) are more heavily proton density weighted than later echoes (e.g., (569, . . . , 5616)) which are more heavily T2 weighted. The magnetic resonance echoes are received and demodulated (38) into a series of data lines. The data lines are sorted (60) between the more heavily proton density weighted data lines and T2 weighted data lines which are reconstructed into a proton density weighted image representation and a T2 weighted image representation. The proton density weighted and T2 weighted image representations are combined (90) to emphasize the black blood from the T2 weighted images and the static tissue from the proton density weighted image. The combined image is a black blood magnetic resonance angiogram.Type: GrantFiled: September 21, 1999Date of Patent: January 22, 2002Assignee: Picker International Inc.Inventors: Kecheng Liu, Jian Lin, Paul M. Margosian
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Patent number: 6339652Abstract: A method of ML-EM image reconstruction is provided for use in connection with a diagnostic imaging apparatus (10) that generates projection data. The method includes collecting projection data, including measured emission projection data and measured transmission projection data. Optionally, the measured transmission projection data is truncated. An initial emission map and attenuation map are assumed. The emission map and the attenuation map are iteratively updated. With each iteration, the emission map is recalculated by taking a previous emission map and adjusting it based upon: (i) the measured emission projection data; (ii) a reprojection of the previous emission map which is carried out with a multi-dimensional projection model; and, (iii) a reprojection of the attenuation map.Type: GrantFiled: November 10, 1999Date of Patent: January 15, 2002Assignee: Picker International, Inc.Inventors: William G. Hawkins, Daniel Gagnon
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Patent number: 6327327Abstract: A computerized tomography system includes a stationary section (A) and a rotating section electrically linked by at least one interconnecting slip ring (D). On one side the slip ring (D) is configured as a series of electrically conductive segments (20A-20H) separated by non-conductive interruptions (22A-22H). On the other side a like number of transmitters (26A-26H) is in selective electrical contact with the conductive segments (20) depending on a position of the rotating frame. Also included is a de-multiplexer (40) which takes image data from the plurality of receivers (RxA-RxH) and rearranges the image data in a determined sequence. Also shown is an angular encoder (46) for providing angular displacement signals (44) to the de-multiplexer (40) for assistance in reconstructing the data channels (30) in the determined sequence.Type: GrantFiled: September 27, 1999Date of Patent: December 4, 2001Assignee: Picker International, Inc.Inventors: Mark D. Herold, Theodore A. Resnick
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Patent number: 6323649Abstract: A gradient amplifier (20), for driving a gradient coil (22) of an MRI scanner, includes a plurality of first modules (60). The first modules (60) provide unipolar PWM control of an input supplied thereto to generate a unipolar waveform. A high voltage DC power supply (64) electrically connected to the first modules (60) supplies the input to the first modules (60). At least one second module (140a, b) is electrically connected to the first modules (60). The second module (140a, b) selectively provides polarity switching of the unipolar waveform output from the first modules (60) to generate a bipolar waveform which drives the gradient coil (22).Type: GrantFiled: September 14, 1999Date of Patent: November 27, 2001Assignee: Picker International, Inc.Inventors: Steven D. Pace, Michael Burl, Douglas M. Blakeley
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Patent number: 6320379Abstract: A probe 1, for use with magnetic resonance imaging apparatus, which is designed to be inserted into and removed from a patient and which comprises a former 2 upon which an r.f. coil 3 is mounted is characterised in that the former also carries at least one transducer or sensor 6-9 by which the targeting of energy relating to an interventional procedure to an area in the vicinity of the transducer may be controlled both as to position and strength.Type: GrantFiled: November 10, 1997Date of Patent: November 20, 2001Assignee: Picker International, Inc.Inventor: Ian R. Young
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Patent number: 6320385Abstract: A multi-channel balun (70, 72) blocks stray RF current from flowing on shield conductors of coaxial RF cables of a magnetic resonance apparatus. The balun comprises a parallel combination of an even number of helical coils of shielded transmission cable (L10, L12; L14, L16, L18, L20) wound in alternate directions such that voltages iduced by their external RF fields cancel. One capacitor (C10; C16, C18) is connected in parallel symmetrically with each pair of helical coils, with trim capacitors (C12; C22) fixed in the coil plug (86, 90) to retune the balun as required. The multi-channel balun (70, 72) accommodates magnetic resonance systems with an odd or even number of channels without requiring shielding. Preferably, the balun (70, 72) is constructed on a single circuit board in a close-packed relationship that is compact and space efficient, yet provides better decoupling from the transmit field.Type: GrantFiled: September 17, 1999Date of Patent: November 20, 2001Assignee: Picker International, Inc.Inventors: Michael Burl, Thomas Chmielewski, William O. Braum
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Patent number: 6314311Abstract: A registration system (200) for use in connection with an image guided surgery system (10) is provided. It includes a medical diagnostic imaging apparatus (100) for collecting image data from a subject (310). An image data processor (130) reconstructs an image representation of the subject from the image data. An image projector (230) depicts the image representation on the subject (310). In a preferred embodiment, the image projector (230) depicts the image representation on the subject (310) such that registration between the subject (310) and the image representation is readily apparent. Preferably, the image projector (230) is a laser lightshow projector, a projection television, or a backlit liquid crystal display device. Optionally, a data processor (210) applies corrections to the image data such that surface contours of the subject (310) are accounted for when the image is projected onto the subject (310).Type: GrantFiled: July 28, 1999Date of Patent: November 6, 2001Assignee: Picker International, Inc.Inventors: Gilbert T. Williams, James M. McNally
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Patent number: 6313629Abstract: A method of magnetic resonance imaging includes subjecting a number of regions of an object being imaged to a magnetic resonance calibration pulse sequence. Each calibration pulse sequence generates a single calibration echo. Each of the calibration echoes are collected and therefrom correction factors are generated. Thereafter, the method includes subjecting the regions of the object being imaged to a plurality of magnetic resonance imaging pulse sequences. Each of the imaging pulse sequences generates a single imaging echo. Each imaging echo is collected into k-space as a plurality of sampled data points. The plurality of sampled data points are adjusted in accordance with the correction factors as each imaging echo is collected into k-space.Type: GrantFiled: November 23, 1999Date of Patent: November 6, 2001Assignee: Picker International, Inc.Inventors: Xecheng Liu, Francis H. Bearden
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Patent number: 6310968Abstract: A method of ML-EM image reconstruction is provided for use in connection with a diagnostic imaging apparatus (10) that generates projection data. The method includes collecting projection data, including measured emission projection data. An initial emission map and attenuation map are assumed. The emission map and the attenuation map are iteratively updated. With each iteration, the emission map is recalculated by taking a previous emission map and adjusting it based upon: (i) the measured emission projection data; (ii) a reprojection of the previous emission map which is carried out with a multi-dimensional projection model; and, (iii) a reprojection of the attenuation map. As well, with each iteration, the attenuation map is recalculated by taking a previous attenuation map and adjusting it based upon: (i) the measured emission projection data; and, (ii) a reprojection of the previous emission map which is carried out with the multi-dimensional projection model.Type: GrantFiled: November 24, 1998Date of Patent: October 30, 2001Assignee: Picker International, Inc.Inventors: William G. Hawkins, Daniel Gagnon
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Patent number: 6307373Abstract: In a magnetic resonance imaging apparatus 1 there is a region of good i.e. uniform field between A and B but, where the field falls off, say, at D, the r.f. excitation pulse can produce an alias image of D which overlies the desired image of say, B. To reduce this effect, the r.f. excitation coil 4 comprises an array of small coils, the amplitude and phase of the excitation of which is controlled so that the r.f. field collapses rapidly outside the region of good field.Type: GrantFiled: June 1, 1999Date of Patent: October 23, 2001Assignee: Picker International, Inc.Inventor: Ian Robert Young
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Patent number: 6294916Abstract: Magnetic resonance imaging apparatus uses magnetic field gradients X, Y, Z to spatially encode the magnetic signals arising from a patient on a couch 2 in bore 1 of a main magnet. Thermal stresses arising from aggressive gradients during multiple acquisitions result in imperfectly repeated gradients and resulting image artefacts. The invention uses a probe 4 provided with a gradient coil set similar to that for imaging, and fed by currents derived from the imaging gradient coils, connected so as to produce an opposing gradient surrounding an MR active substance in the probe. This enables a probe with a sufficiently large amount of MR active substance to produce a useful signal to be used to monitor the gradient, while overcoming the de-phasing problem. which would otherwise occur. Closed loop control of gradients thereby becomes possible.Type: GrantFiled: October 29, 1999Date of Patent: September 25, 2001Assignee: Picker International, Inc.Inventors: Michael Burl, Ian Robert Young
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Patent number: 6281773Abstract: A high temperature superconductor (HTSC) 5 is magnetized between drive coils 1,2 forming poles of a magnet connected by an iron yoke 9 by relative movement of a vacuum insulated cryostat 4 containing the HTSC and the magnetizing magnet, in order to magnetize a large area of HTSC using a magnet with a small region 3 of magnetizing flux. Alternatively, the HTSC 5 may be contained in an evacuated region of a cryostat containing the magnetizing magnet. An interconnecting chamber allows the HTSC to be moved between an operative region and a magnetizing region without substantial loss of vacuum.Type: GrantFiled: July 16, 1999Date of Patent: August 28, 2001Assignee: Picker International, Inc.Inventor: Ian Robert Young
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Patent number: 6276145Abstract: A CT scanner (10) for obtaining a medical diagnostic image of a subject includes a stationary gantry (12), and a rotating gantry (16) rotatably supported on the stationary gantry (12) for rotation about the subject. A fluid bearing (18) is interposed between the stationary and rotating gantries (12) and (16), respectively. The fluid bearing (18) provides a fluid barrier (110) which separates the rotating gantry (16) from the stationary gantry (12). In a preferred embodiment, the fluid bearing (18) provides for quieter CT scanner operation at high rotational speeds. Moreover, eliminating the physical contact between the gantries minimizes wear and optimizes longevity.Type: GrantFiled: October 27, 1999Date of Patent: August 21, 2001Assignee: Picker International, Inc.Inventors: Ronald Bryan Sharpless, William Charles Brunnett
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Patent number: 6278275Abstract: A gradient coil assembly (22) generates substantially linear magnetic gradients across the central portion of an examination region (14). The gradient coil assembly (22) includes primary x, y, and z-gradient coils (62, 66, 68) which generate a gradient magnetic field (90) having a non-zero first derivative in and adjacent the examination region. Preferably, the gradient coil assembly (22) includes secondary, shielding x, y, and z coils which generate a magnetic field which substantially cancels, in an area outside a region defined by the shielding coils, a fringe magnetic field generated by the primary gradient coils. The existence of a non-zero first derivative in and adjacent the examination region eliminates aliasing effects attributable to the non-unique gradient field values on either side of a rollover point (82). The non-unique values of the gradient magnetic field adjacent the rollover point caused structure near the rollover point to overlay each other (FIGS. 7B, 8B).Type: GrantFiled: October 18, 1999Date of Patent: August 21, 2001Assignee: Picker International, Inc.Inventors: Labros S. Petropoulos, Heidi A. Schlitt