Patents by Inventor George J. Misic

George J. Misic 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: 4920318
    Abstract: A resonance exciting coil (C) excites magnetic resonance in nuclei disposed in an image region in which a main magnetic field and transverse gradients have been produced. A flexible receiving coil (D) includes a flexible plastic sheet (40) on which one or more loops (20) are adhered to receive signals from the resonating nuclei. Velcro straps (46) strap the flexible sheet and the attached coil into close conformity with the surface of the portion of the patient to be imaged. An impedance matching or coil resonant frequency adjusting network (50) is mounted on the flexible sheet for selectively adjusting at least one of an impedance match and the peak sensitivity resonant frequency of the receiving coil. A preamplifier (52) amplifies the received signals prior to transmission on a cable (24). A selectively variable voltage source (70) applies a selectively adjustable DC bias voltage to the cable for selectively adjusting at least one of the impedance match and the LC resonant frequency of the receiving coil.
    Type: Grant
    Filed: October 3, 1988
    Date of Patent: April 24, 1990
    Assignee: Picker International, Inc.
    Inventors: George J. Misic, Gregory C. Hurst, G. Neil Holland, John L. Patrick, III, Paul T. Orlando
  • Patent number: 4879516
    Abstract: A magnetic resonance imager includes a quadrature coil assembly (20) for transmitting radio frequency signals into and receiving magnetic resonance signal from an examination region. The quadrature coils assembly includes a first coil (22) and a second coil (24). A shunt path (32, 64, 74, 84, 94, 98, 100, 112, 114, 122) provides a current path by shunting at least a portion of one of the coils. A variable impedance (34, 66, 76, 86, 96, 110, 120) adjusts the amount of current flow through the shunt path and the current flow through the bypassed coil portion. More specifically, adjusting the impedance changes the magnetization vector generated by the coil assembly in a transmit mode and adjusts their relative isolation in a receive mode. The quadrature coils are mounted such that they are offset by about, but not quite, 90.degree.. The variable impedance is adjusted until the offset is brought precisely to 90.degree..
    Type: Grant
    Filed: May 26, 1988
    Date of Patent: November 7, 1989
    Assignee: Picker International, Inc.
    Inventors: Mehrdad Mehdizadeh, John L. Patrick, George J. Misic
  • Patent number: 4841248
    Abstract: Magnets (12) create a main magnetic field along a z-axis through an image region. A localized coil (D) is disposed in the image region at least to receive magnetic resonance signals from nuclei of the subject which have been induced to resonance. The localized coil includes an inner conductor (30), preferably a plate, which defines a current path extending along the z-axis. The inner conductor is mounted closely adjacent and parallel to a surface of the subject. An outer conductor (32), preferably also a plate, is mounted parallel to but further from the subject than the first conductor. A connecting member (34) interconnects a first end of the inner and outer conductors and is disposed perpendicular to the z-axis. A matching circuit (36) including capacitors (50) which define the resonant frequency of the coil are connected adjacent second ends of the inner and outer conductors.
    Type: Grant
    Filed: August 17, 1987
    Date of Patent: June 20, 1989
    Assignee: Picker International, Inc.
    Inventors: Mehrdad Mehdizadeh, John L. Patrick, George J. Misic
  • Patent number: 4839594
    Abstract: Magnet (12) creates a main magnetic field along a z-axis through an image region. A localized coil (D) is disposed in the image region at least to receive magnetic resonance signals from nuclei of the subject which have been induced to resonance. The localized coil includes an inner conductor (30), an outer conductor (32), and a dielectric material (52) therebetween. The outer conductor defines a gap (50) midway between its ends. One end of the inner conductor is connected with a gate of an FET transistor (66) and the outer conductor is connected with its source. The transistor source and drain are connected by a coaxial transmission cable (38) with a DC power supply (70) which provides a DC bias across the transistor source and drain. The cable also connects the transistor with a radio frequency receiver (40) to convey preamplified magnetic resonance signals thereto.
    Type: Grant
    Filed: November 13, 1987
    Date of Patent: June 13, 1989
    Assignee: Picker International, Inc.
    Inventors: George J. Misic, G. Neil Holland, Mehrdad Mehdizadeh, John L. Patrick
  • Patent number: 4797617
    Abstract: A nuclear magnetic resonance radio frequency coil. The disclosed coil provides high frequency resonance signals for perturbing a magnetic field within the coil. The coil is impedance matched and tuned with adjustable capacitors. A balanced configuration is achieved with a co-axial cable chosen to phase shift an energization signal coupled to the coil. The preferred coil is a thin metallic foil having a shorting conductor, four wing conductors, and uniquely shaped parallel cross conductors connecting the shorting and wing conductors. When mounted to an rf transmissive plastic substrate and energized the coil produces a homogenous field within a region of interest the size of a patient head. A semicircular balanced feedbar arrangement is used to minimize undesired field contributions.
    Type: Grant
    Filed: November 21, 1986
    Date of Patent: January 10, 1989
    Assignee: Picker International, Inc.
    Inventors: George J. Misic, Aarne Lillo, John L. Patrick, G. Neil Holland
  • Patent number: 4793356
    Abstract: A resonance exciting coil (C) excites magnetic resonance in nuclei disposed in an image region in which a main magnetic field and transverse gradients have been produced. A flexible receiving coil (D) includes a flexible plastic sheet (40) on which one or more loops (20) are adhered to receive signals from the resonating nuclei. Velcro straps (46) strap the flexible sheet and the attached coil into close conformity with the surface of the portion of the patient to be imaged. An impedance matching or coil resonant frequency adjusting network (50) is mounted on the flexible sheet for selectively adjusting at least one of an impedance match and the peak sensitivity resonant frequency of the receiving coil. A preamplifier (52) amplifies the received signals prior to transmission on a cable (24). A selectively variable voltage source (70) applies a selectively adjustable DC bias voltage to the cable for selectively adjusting at least one of the impedance match and the LC resonant frequency of the receiving coil.
    Type: Grant
    Filed: August 14, 1985
    Date of Patent: December 27, 1988
    Assignee: Picker International, Inc.
    Inventors: George J. Misic, Gregory C. Hurst, G. Neil Holland, John L. Patrick, III, Paul T. Orlando
  • Patent number: 4764726
    Abstract: During a transmit cycle portion, a radio frequency transmitter (C) continuously generates an AC biasing signal and selectively generates a radio frequency signal. The AC biasing signal gates a first switch (10) and a second switch (32) such that the radio frequency signals from the transmitter are conducted to a magnetic resonance probe (E) but are blocked from being conducted to a receiver (F). A first filter (20) prevents the bias signals from being applied to the probe. The second switch includes a pair of crossed diodes (34, 36) which are gated conductive by the AC bias signal. A filter (72) passes the radio frequency signals but not the bias signals to ground to prevent the radio frequency signals from reaching the receiver. A filter (80) allows the bias signals to be applied across a load (88) such that the transmitter sees the load at the bias signal frequency. Another filter (40) prevents the bias signal from reaching the transmitter.
    Type: Grant
    Filed: September 5, 1986
    Date of Patent: August 16, 1988
    Assignee: Picker International, Inc.
    Inventors: George J. Misic, Paul T. Orlando
  • Patent number: 4740751
    Abstract: A resonator coil assembly (32) includes a dielectric sleeve (40) on which a first resonator coil portion (42) and a second resonator coil portion (44), each of copper foil, are adhered. The dielectric sleeve is dimensioned to receive a human torso therein and in one embodiment (FIG. 1) is circular in cross section and in another (FIG. 4) is elliptical in cross section. A pair of adjustable tuning capacitances (64, 66) and a pair of adjustable matching capacitances (68, 70) are interconnected between one end of the each coil portion and a metal bore liner (54). An opposite end of the coil portions are capacitively coupled to each other (FIG. 1) or to the bore liner (FIG. 3). A half wave length cable (72) interconnects the junctions between the first and second tuning and matching capacitances. One of these junctions is connected by a cable (74) with a radio frequency generator (30) and a radio receiver (34).
    Type: Grant
    Filed: August 7, 1986
    Date of Patent: April 26, 1988
    Assignee: Picker International, Inc.
    Inventors: George J. Misic, John L. Patrick
  • Patent number: 4731584
    Abstract: A magnetic field control (A) causes a magnetic field through an imaging region of a magnetic resonance spectrometer. A radio frequency generator (20) generates radio frequency signals which are transmitted on a transmission line (22) to a probe coil (C). Magnetic resonance signals received by the probe coil (C) are conveyed over the transmission line to a radio frequency receiver (24) for reconstruction into a magnetic resonance image. An inductive matching network (D) is connected between the probe coil and the transmission line for matching the resistive impedance of the coil with the resistive impedance of the transmission line and for resonating the coil at a frequency other than its self resonance frequency. When the probe coil is operated above the self resonance frequency, it is capacitively reactive. An inductor (40) is connected across coil feed points (30, 32) of the probe coil.
    Type: Grant
    Filed: August 14, 1986
    Date of Patent: March 15, 1988
    Assignee: Picker International, Inc.
    Inventors: George J. Misic, John L. Patrick
  • Patent number: 4684895
    Abstract: In a magnetic resonance imager or other spectrometer, an interface (D) selectively connects quadrature probe coils (E) with a transmitter (C) and with a receiver (F). The interface includes a first RF switch (10), such as a first PIN diode (12) which has a low radio frequency impedance state for passing transmitted radio frequency signals to the probe coils and a high radio frequency impedance state for blocking the passage of radio frequency signals to the probe coils. A quarter wave length cable (20) or the equivalent is connected between the probe coils to shift the phase of the radio frequency signals 90 degrees. A second radio frequency switch (40) includes a second quarter wave length cable (42) and a second pin diode (44) which selectively pass and block radio frequency signals from passing between the probe coils and the receiver.
    Type: Grant
    Filed: August 5, 1985
    Date of Patent: August 4, 1987
    Assignee: Picker International, Inc.
    Inventor: George J. Misic
  • Patent number: 4634980
    Abstract: A nuclear magnetic resonance radio frequency coil. The disclosed coil provides high frequency resonance signals for perturbing a magnetic field within the coil. The coil is impedance matched and tuned with adjustable capacitors. A balanced configuration is achieved with a co-axial cable chosen to phase shift an energization signal coupled to the coil. The preferred coil is a thin metallic foil having a shorting conductor, four wing conductors, and uniquely shaped parallel cross conductors connecting the shorting and wing conductors. When mounted to a rf transmissive plastic substrate and energized the coil produces a homogeneous field within a region of interest the size of a patient head. A semicircular balanced feedbar arrangement is used to minimize undesired field contributions.
    Type: Grant
    Filed: August 16, 1984
    Date of Patent: January 6, 1987
    Assignee: Picker International, Inc.
    Inventors: George J. Misic, Aarne Lillo, John L. Patrick, G. Neil Holland