Patents by Inventor Albert Macovski

Albert Macovski 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: 4685468
    Abstract: NMR imaging is achieved in the presence of temporal variations in the magnetic field. The volume is excited using broadband excitation. A signal is picked up in the plane of interest, using a small coil, and used to determine the frequency of the subsequent plane-selecting excitation. A similar coil can be used to pick up the signal used to image the plane using projections all in the same direction. This latter signal is used to provide the demodulation signals to decompose the selected plane into its constituent elements. In both cases, involving the excitation and decoding signals, drifts in the magnetic field are compensated for.
    Type: Grant
    Filed: March 18, 1983
    Date of Patent: August 11, 1987
    Inventor: Albert Macovski
  • Patent number: 4686695
    Abstract: An x-ray beam is scanned through a sequence of subsections of a volume. At each position the x-ray transmission is measured at two energies. The resultant transmission signals are processed to produce a signal representing the projected amount of a specific material in the volume. The two energies are chosen so that the mass attenuation coefficients of bone and soft tissue are comparable to each other.
    Type: Grant
    Filed: November 17, 1980
    Date of Patent: August 11, 1987
    Assignee: Board of Trustees of the Leland Stanford Junior University
    Inventor: Albert Macovski
  • Patent number: 4665366
    Abstract: The nuclei in a volume are imaged using a sequence of excitations in the presence of one or more time-varying gradient fields. The resultant phase variations are cancelled to isolate a region of the volume. Various phase-modulation functions are used to provide a desired localization function. The excitation variations can be combined with time-varying gradients during the reception interval.
    Type: Grant
    Filed: March 11, 1985
    Date of Patent: May 12, 1987
    Inventor: Albert Macovski
  • Patent number: 4662379
    Abstract: A method of imaging a blood vessel such as a coronary artery includes the steps of a dual energy providing radiation source and a radiation detector on opposing sides of a target area and at a plurality of angular positions through the target area. The radiation source is gated at the plurality of positions after administering a contrast agent intravenously to obtain a first plurality of detector signals indicative of a first plurality of views through said target area. The first plurality of detector signals are then tomosynthesisly combined to provide a planar image through the target area. Preferably, the gating of the radiation source after administering a contrast agent includes gating based on a selected time using an electrocardiogram, and the gating is at at least two energy levels to obtain detector signals at each energy level indicative of said plurality of views. Soft tissue is eliminated by combining signals at the least two image levels.
    Type: Grant
    Filed: August 27, 1986
    Date of Patent: May 5, 1987
    Assignee: Stanford University
    Inventor: Albert Macovski
  • Patent number: 4639671
    Abstract: The nuclei in a volume are imaged using one or more time-varying gradient fields. The resultant signals are heterodyned using a signal having a related time-varying component. Equivalently, the spectrum of the resultant signal is convolved with the spectrum of the heterodyne Signal. Following integration, depending on the amplitude of the time-varying component of the heterodyne signal, any point in the volume can be studied from the same received signal.
    Type: Grant
    Filed: April 24, 1984
    Date of Patent: January 27, 1987
    Assignee: General Electric Company
    Inventor: Albert Macovski
  • Patent number: 4623844
    Abstract: The volume of interest is excited. An array of pickup coils with water cores provide an array of signals whose frequencies indicate the magnetic field distribution. These frequencies are estimated and used to produce controlled magnetic field inhomogeneities which substantially cancel the undesired inhomogeneities in the field. The control signals can be stored and updated with each subsequent excitation.
    Type: Grant
    Filed: July 18, 1983
    Date of Patent: November 18, 1986
    Inventor: Albert Macovski
  • Patent number: 4623843
    Abstract: NMR imaging of an object is achieved in the presence of temporal variations in the magnetic field. A reference volume is separately excited. The resultant signal is used to find the correct excitation frequency for the desired plane. Prior to receiving the signal from the object reference volumes on either side are excited to provide signals which are used to form the demodulation and sampling signals.
    Type: Grant
    Filed: August 1, 1984
    Date of Patent: November 18, 1986
    Inventor: Albert Macovski
  • Patent number: 4579121
    Abstract: A cross-sectional image of the NMR activity in the body is formed by taking a sequence of projections, each having a different transverse gradient structure. Following each excitation the spins in the cross section are driven back to equilibrium. For imaging relaxation times, the sequence of projection signals are processed so as to represent an acquisition at a specific desired time.
    Type: Grant
    Filed: February 18, 1983
    Date of Patent: April 1, 1986
    Inventor: Albert Macovski
  • Patent number: 4578803
    Abstract: Energy-selective x-ray images are produced using two scintillating screens separated by an x-ray hardening filter. Photosensitive surfaces individually receive the light images from each screen. The resultant image transparencies are read out optically using a partially reflecting mirror between the transparencies and detecting the reflected and transmitted light. The x-ray spectral separation between the two acquired images can be further increased by using an x-ray source filter having a K-absorption edge in the vicinity of the region of overlap of the two spectra.
    Type: Grant
    Filed: March 16, 1984
    Date of Patent: March 25, 1986
    Inventor: Albert Macovski
  • Patent number: 4577152
    Abstract: Two-dimensional projection measurements are formed of the NMR activity within a volume. Measurements are made using different intensities of the main magnetic field, using the different dependencies of relaxation times on magnetic field. The projection measurements are combined to obtain projection images of specific materials within the volume. Projection images are obtained of specific regions within the volume by insuring that the unwanted regions remain insensitized. For improved SNR, projection measurements are repeated to obtain spin-echo signals. The measurements of relaxation times are interleaved so that the data acquisition can occur rapidly.
    Type: Grant
    Filed: April 11, 1983
    Date of Patent: March 18, 1986
    Inventor: Albert Macovski
  • Patent number: 4565968
    Abstract: A two-dimensional projection image of the NMR activity within a volume is obtained. The signals due to static material are cancelled and do not appear in the projection image. The signals due to moving blood in vessels produce an isolated image of the vessels with the superimposed structure removed. The excitation of a plane is accomplished using a single excitation pulse without requiring an a.c. gradient. The uniformity requirement of the inversion excitation is minimized. Images are generated which distinguish the direction of flow.
    Type: Grant
    Filed: February 16, 1983
    Date of Patent: January 21, 1986
    Inventor: Albert Macovski
  • Patent number: 4551680
    Abstract: Two-dimensional projection measurements are formed of the NMR activity of a selected region of a volume. These represent different properties of the materials within the volume including density and relaxation times. The measurements of the different properties are processed to produce projection images of specific materials within the volume. Projection images are also obtained of moving materials only to provide isolated vessel images.
    Type: Grant
    Filed: April 21, 1983
    Date of Patent: November 5, 1985
    Inventor: Albert Macovski
  • Patent number: 4549307
    Abstract: The image signal in a radiation imaging system is improved by establishing a scattered radiation signal and subtracting the scatter radiation signal from the detected radiation signal. The scatter radiation signal is established by shielding portions of the detector and measuring radiation at the shielded portions of the detector. The total scatter radiation signal is interpolated from spatial distribution of the radiation measured at the shielded areas.
    Type: Grant
    Filed: August 9, 1984
    Date of Patent: October 22, 1985
    Assignee: The Board of Trustees of The Leland Stanford, Junior University
    Inventor: Albert Macovski
  • Patent number: 4528985
    Abstract: A two-dimensional projection image of the NMR activity within a volume is obtained. The signals due to static material are cancelled and do not appear in the projection image. The signals due to moving blood in vessels produce an isolated image of the vessels with the superimposed structure removed.
    Type: Grant
    Filed: December 21, 1981
    Date of Patent: July 16, 1985
    Inventor: Albert Macovski
  • Patent number: 4523596
    Abstract: A two-dimensional projection image of the NMR activity within a volume is obtained. The signals due to static material are cancelled and do not appear in the projection image. The signals due to moving blood in vessels produce an isolated image of the vessels with the superimposed structure removed.
    Type: Grant
    Filed: September 10, 1984
    Date of Patent: June 18, 1985
    Inventor: Albert Macovski
  • Patent number: 4521734
    Abstract: The electromagnet providing the main field of the nuclear magnetic resonance (nmr) imaging system is turned up during the data acquisition region and turned down between data acquisition periods. The data acquisition consists of the excitation of the spins and the reception of the associated signals.
    Type: Grant
    Filed: January 13, 1983
    Date of Patent: June 4, 1985
    Inventor: Albert Macovski
  • Patent number: 4486708
    Abstract: Two-dimensional projection measurements are formed of the NMR activity within a volume. These represent different properties of the materials within the volume including density, the longitudinal relaxation time and the spin-spin relaxation time. The measurements of the different properties are processed to produce projection images of specific materials within the volume. Projection images are also obtained of specific regions within the volume.
    Type: Grant
    Filed: December 21, 1981
    Date of Patent: December 4, 1984
    Inventor: Albert Macovski
  • Patent number: 4463375
    Abstract: In a multiple-measurement system, a weighted sum of the measurements is used to provide a selective image. An additional weighted sum is used to provide an increased signal-to-noise ratio of some desired parameter of the image. The high frequency components of the increased signal-to-noise ratio image are combined with the low frequency components of the selective image to provide a selective image with improved signal-to-noise ratio. The combining operation can utilize the ratios of the derivatives in each signal to provide the correct amount of high frequency signal at each transition.
    Type: Grant
    Filed: September 7, 1982
    Date of Patent: July 31, 1984
    Assignee: The Board of Trustees of the Leland Standford Junior University
    Inventor: Albert Macovski
  • Patent number: 4413353
    Abstract: X-ray information is encoded onto photographic film by placing an optical grating between the light-emitting scintillating screen and the photographic emulsion. Information at different energies is encoded by displacing the grating between exposures or by using static gratings with an energy-selective dual screen.
    Type: Grant
    Filed: September 3, 1981
    Date of Patent: November 1, 1983
    Inventors: Albert Macovski, Bruno Strul, Robert E. Alvarez
  • Patent number: 4400721
    Abstract: The response of color television signals are improved by adding a high frequency luminance component which is proportional to the color-difference signal so as to provide color signals with correct transitions. The ratio of the derivative of the color difference signal to the derivative of the low frequency portion of the luminance signal is used to weight the amplitude of the luminance component.
    Type: Grant
    Filed: July 13, 1981
    Date of Patent: August 23, 1983
    Inventor: Albert Macovski