Patents by Inventor Krishna S. Nayak

Krishna S. Nayak 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: 11982726
    Abstract: Tracer kinetic models are utilized as temporal constraints for highly under-sampled reconstruction of DCE-MRI data. In one embodiment, a method for improving dynamic contrast enhanced imaging. The method includes steps of administering a magnetic resonance contrast agent to a subject and then collecting magnetic resonance contrast agent from the subject. A tracer kinetic model (i.e. eTofts or Patlak) is selected to be applied to the magnetic resonance imaging data. The tracer kinetic model is applied to the magnetic resonance imaging data. Tracer kinetic maps and dynamic images are simultaneously reconstructed and a consistency constraint is applied. The proposed method allows for easy use of different tracer kinetic models in the formulation and estimation of patient-specific arterial input functions jointly with tracer kinetic maps.
    Type: Grant
    Filed: April 15, 2019
    Date of Patent: May 14, 2024
    Assignee: University of Southern California
    Inventors: Krishna S. Nayak, Yannick Bliesener, Yi Guo, Yinghua Zhu, Sajan Goud Lingala, Robert Marc Lebel
  • Publication number: 20190317171
    Abstract: Tracer kinetic models are utilized as temporal constraints for highly under-sampled reconstruction of DCE-MRI data. In one embodiment, a method for improving dynamic contrast enhanced imaging. The method includes steps of administering a magnetic resonance contrast agent to a subject and then collecting magnetic resonance contrast agent from the subject. A tracer kinetic model (i.e. eTofts or Patlak) is selected to be applied to the magnetic resonance imaging data. The tracer kinetic model is applied to the magnetic resonance imaging data. Tracer kinetic maps and dynamic images are simultaneously reconstructed and a consistency constraint is applied. The proposed method allows for easy use of different tracer kinetic models in the formulation and estimation of patient-specific arterial input functions jointly with tracer kinetic maps.
    Type: Application
    Filed: April 15, 2019
    Publication date: October 17, 2019
    Inventors: KRISHNA S. NAYAK, YANNICK BLIESENER
  • Patent number: 10203392
    Abstract: A magnetic resonance imaging system may include: a magnet; gradient coils; an RF pulse transmitter; an RF receiver that receives MR signals from tissue that has been exposed to RF pulses from the RF pulse generator, gradient fields from the gradient coils, and a magnetic field from the magnet; a system controller that controls the magnet, gradient coils, RF pulse transmitter, and RF receiver so as to generate data representative of at least a portion of the composition of an object, including controlling the gradient coils and RF receiver so as to cause MRI data to be acquired that includes information about at least one attribute of the object at different points in time and that represents an incomplete sample of a portion of k-space that is a Fourier transform of the object; and a data processing system that generates one or more images of at least a portion of the object based on the MRI data.
    Type: Grant
    Filed: March 21, 2016
    Date of Patent: February 12, 2019
    Assignee: UNIVERSITY OF SOUTHERN CALIFORNIA
    Inventors: Yinghua Zhu, Yi Guo, Krishna S. Nayak, Robert Marc Lebel
  • Publication number: 20170258409
    Abstract: A magnetic resonance imaging system may include a magnet, gradient coils, an RF pulse transmitter, an RF receiver that receives MR signals from tissue that has been exposed to RF pulses, gradient fields, and a magnetic field, and a computer that includes a processor. The computer may have a configuration that: causes the RF pulse transmitter and gradient coils to emit multiple labeling pulses at predetermined labeling times directed to blood in a subject; causes the RF pulse transmitter, gradient coils, and magnet to generate MR signals directed to tissue at one or more spatial locations within the subject that receives the blood; causes the RF receiver to receive MR signals emitted by the tissue at predetermined imaging times; generates an image of the tissue based on the received MR signals; repeats the foregoing four actions one or more times; and generates information indicative of perfusion within the tissue based on the generated images.
    Type: Application
    Filed: December 1, 2015
    Publication date: September 14, 2017
    Inventors: Hung Phi Do, Terrence Jao, Krishna S. Nayak
  • Patent number: 9739861
    Abstract: An MRI scanner may include one or more gradient waveform generators, gradient amplifiers, gradient coils, an RF waveform generator, an RF amplifier, an RF coil, a superconducting magnet, an RF detector; a digitizer, and a computer system that controls the one or more gradient waveform generators and the RF waveform generator so as to generate a magnetization saturation preparation pulse sequence that includes a tip-down pulse that is insensitive to RF field inhomogeneity followed by a tip-back pulse that employs a conjugate symmetry constraint in its energy spectrum.
    Type: Grant
    Filed: April 18, 2013
    Date of Patent: August 22, 2017
    Assignee: University of Southern California
    Inventors: Travis B. Smith, Krishna S. Nayak
  • Publication number: 20160274201
    Abstract: A magnetic resonance imaging system may include: a magnet; gradient coils; an RF pulse transmitter; an RF receiver that receives MR signals from tissue that has been exposed to RF pulses from the RF pulse generator, gradient fields from the gradient coils, and a magnetic field from the magnet; a system controller that controls the magnet, gradient coils, RF pulse transmitter, and RF receiver so as to generate data representative of at least a portion of the composition of an object, including controlling the gradient coils and RF receiver so as to cause MRI data to be acquired that includes information about at least one attribute of the object at different points in time and that represents an incomplete sample of a portion of k-space that is a Fourier transform of the object; and a data processing system that generates one or more images of at least a portion of the object based on the MRI data.
    Type: Application
    Filed: March 21, 2016
    Publication date: September 22, 2016
    Applicant: UNIVERSITY OF SOUTHERN CALIFORNIA
    Inventors: Yinghua Zhu, Yi Guo, Krishna S. Nayak, Robert Marc Lebel
  • Patent number: 8908980
    Abstract: A method implemented in a graphics engine for decoding image blocks to derive an original image is provided. The method comprises receiving at least one encoded image data block at a block decoder, the at least one encoded image data block comprising a plurality of codewords and a bitmap. The method further comprises determining a block type based on the plurality of codewords and selecting a decoder unit among a plurality of decoder units in accordance with the block type.
    Type: Grant
    Filed: December 3, 2012
    Date of Patent: December 9, 2014
    Assignee: S3 Graphics Co., Ltd.
    Inventors: Zhou Hong, Konstantine I. Iourcha, Krishna S. Nayak
  • Patent number: 8326055
    Abstract: A method implemented in a graphics engine for decoding image blocks to derive an original image is provided. The method comprises receiving at least one encoded image data block at a block decoder, the at least one encoded image data block comprising a plurality of codewords and a bitmap. The method further comprises determining a block type based on the plurality of codewords and selecting a decoder unit among a plurality of decoder units in accordance with the block type.
    Type: Grant
    Filed: June 11, 2010
    Date of Patent: December 4, 2012
    Assignee: S3 Graphics Co., Ltd.
    Inventors: Zhou Hong, Konstantine I. Iourcha, Krishna S. Nayak
  • Patent number: 8324898
    Abstract: Embodiments of the present disclosure are directed to systems and methods for providing tailored RF pulse trains, based on estimated B0 and B1 profiles, for uniform saturation for MRI techniques. The tailored pulse trains are optimized to minimize residual longitudinal magnetization in target tissue. The B0 and B1 profiles can be measured a priori over a desired region of a patient, e.g., the heart, and can overcome or mitigate SAR and B1 inhomogeneity constraints. In exemplary embodiments, the tailored pulse trains can include hard pulses with unequal weighting. In other embodiments, the tailored pulse trains can include BIR-4 pulse trains that are optimized to minimize residual longitudinal magnetization in target tissue. The tailored pulse train designs can improve the immunity to B1 variation while maintaining low RF power. MRI systems, methods, and controllers for providing tailored pulse trains are described.
    Type: Grant
    Filed: November 16, 2009
    Date of Patent: December 4, 2012
    Assignee: University of Southern California
    Inventors: Kyunghyun Sung, Krishna S. Nayak
  • Patent number: 8283924
    Abstract: Magnetic resonance imaging techniques are described that utilize bSSFP sequences in which two or more gradient waveforms are interleaved in a “groupwise” fashion, i.e., each waveform is executed consecutively two or more times before switching to the other waveform, where “N” counts the number of times each waveform is executed consecutively. As a result, embodiments of the present disclosure can mitigate steady-state signal distortions or artifacts in interleaved balanced steady-state free precession (bSSFP) caused by slightly unbalanced eddy-current fields. Related MRI systems are also described.
    Type: Grant
    Filed: October 20, 2009
    Date of Patent: October 9, 2012
    Assignee: University of Southern California
    Inventors: Jon-Fredrik Nielsen, Krishna S. Nayak
  • Patent number: 8269494
    Abstract: Techniques and systems for magnetic resonance imaging. In one aspect, preparatory pulse sequences precede alternating repetition time steady state free precession (ATR SSFP) pulse sequences to enable image acquisition before reaching a steady-state equilibrium. The design of the preparatory sequences is based on a two step process: First an oscillatory residue is expressed in terms of a window (e.g., a Kaiser-Bessel window) and scale parameters. Second the oscillatory residue is minimized to determine the scale parameters according to a desired application (e.g. ATR SSFP, optimized for fat, water, etc.) The preparation scheme described in this specification can be applied to arbitrary repetition times and RF phase cycling combinations.
    Type: Grant
    Filed: March 2, 2009
    Date of Patent: September 18, 2012
    Assignee: University of Southern California
    Inventors: Hsu-Lei Lee, Krishna S. Nayak
  • Patent number: 8212561
    Abstract: Referenceless techniques for flow imaging are described that exploit a refocusing property of balanced steady state free precession (“SSFP”) magnetic resonance imaging (“MRI”), and achieve up to approximately a 50% reduction in total scan time. With the echo time set to one half of the sequence repetition time (TE=TR/2), non-flow-related image phase tends to vary smoothly across the field-of-view, and can be estimated from static tissue regions to produce a phase reference for nearby voxels containing flowing blood. These approaches produce accurate in vivo one-dimensional velocity estimates in half the scan time compared with conventional balanced SSFP phase-contrast methods. The feasibility of referenceless time-resolved 3D flow imaging (called “7D” flow) is demonstrated for a carotid bifurcation application from just three acquisitions. Related systems are also described. Other attributes such as blood acceleration can also be imaged with such techniques.
    Type: Grant
    Filed: October 20, 2009
    Date of Patent: July 3, 2012
    Assignee: University of Southern California
    Inventors: Jon-Fredrik Nielsen, Krishna S. Nayak
  • Publication number: 20110002537
    Abstract: A method implemented in a graphics engine for decoding image blocks to derive an original image is provided. The method comprises receiving at least one encoded image data block at a block decoder, the at least one encoded image data block comprising a plurality of codewords and a bitmap. The method further comprises determining a block type based on the plurality of codewords and selecting a decoder unit among a plurality of decoder units in accordance with the block type.
    Type: Application
    Filed: June 11, 2010
    Publication date: January 6, 2011
    Applicant: VIA TECHNOLOGIES, INC.
    Inventors: Zhou Hong, Konstantine I. Iourcha, Krishna S. Nayak
  • Patent number: 7801363
    Abstract: An image processing system including an image encoder and image decoding system is provided. The image encoder system includes an image decomposer, a block encoder, and an encoded image composer. The image decomposer decomposes the image into blocks. The block encoder, which includes a selection module, a codeword generation module and a construction module, processes the blocks. Specifically, the selection module computes a set of parameters from image data values of a set of image elements in the image block. The codeword generation module generates codewords, which the construction module uses to derive a set of quantized image data values. The construction module then maps each of the image element's original image data values to an index to one of the derived image data values. The image decoding system reverses this process to reorder decompressed image blocks in an output data file.
    Type: Grant
    Filed: March 2, 2006
    Date of Patent: September 21, 2010
    Assignee: S3 Graphics Co., Ltd.
    Inventors: Zhou Hong, Konstantine I. Iourcha, Krishna S. Nayak
  • Publication number: 20100127703
    Abstract: Embodiments of the present disclosure are directed to systems and methods for providing tailored RF pulse trains, based on estimated B0 and B1 profiles, for uniform saturation for MRI techniques. The tailored pulse trains are optimized to minimize residual longitudinal magnetization in target tissue. The B0 and B1 profiles can be measured a priori over a desired region of a patient, e.g., the heart, and can overcome or mitigate SAR and B1 inhomogeneity constraints. In exemplary embodiments, the tailored pulse trains can include hard pulses with unequal weighting. In other embodiments, the tailored pulse trains can include BIR-4 pulse trains that are optimized to minimize residual longitudinal magnetization in target tissue. The tailored pulse train designs can improve the immunity to B1 variation while maintaining low RF power. MRI systems, methods, and controllers for providing tailored pulse trains are described.
    Type: Application
    Filed: November 16, 2009
    Publication date: May 27, 2010
    Applicant: UNIVERSITY OF SOUTHERN CALIFORNIA
    Inventors: Kyunghyun Sung, Krishna S. Nayak
  • Publication number: 20100109665
    Abstract: Referenceless techniques for flow imaging are described that exploit a refocusing property of balanced steady state free precession (“SSFP”) magnetic resonance imaging (“MRI”), and achieve up to approximately a 50% reduction in total scan time. With the echo time set to one half of the sequence repetition time (TE=TR/2), non-flow-related image phase tends to vary smoothly across the field-of-view, and can be estimated from static tissue regions to produce a phase reference for nearby voxels containing flowing blood. These approaches produce accurate in vivo one-dimensional velocity estimates in half the scan time compared with conventional balanced SSFP phase-contrast methods. The feasibility of referenceless time-resolved 3D flow imaging (called “7D” flow) is demonstrated for a carotid bifurcation application from just three acquisitions. Related systems are also described. Other attributes such as blood acceleration can also be imaged with such techniques.
    Type: Application
    Filed: October 20, 2009
    Publication date: May 6, 2010
    Applicant: UNIVERSITY OF SOUTHERN CALIFORNIA
    Inventors: Jon-Fredrik Nielsen, Krishna S. Nayak
  • Publication number: 20100102816
    Abstract: Magnetic resonance imaging techniques are described that utilize bSSFP sequences in which two or more gradient waveforms are interleaved in a “groupwise” fashion, i.e., each waveform is executed consecutively two or more times before switching to the other waveform, where “N” counts the number of times each waveform is executed consecutively. As a result, embodiments of the present disclosure can mitigate steady-state signal distortions or artifacts in interleaved balanced steady-state free precession (bSSFP) caused by slightly unbalanced eddy-current fields. Related MRI systems are also described.
    Type: Application
    Filed: October 20, 2009
    Publication date: April 29, 2010
    Applicant: UNIVERSITY OF SOUTHERN CALIFORNIA
    Inventors: Jon-Fredrik Nielsen, Krishna S. Nayak
  • Publication number: 20090256563
    Abstract: Techniques and systems for magnetic resonance imaging. In one aspect, preparatory pulse sequences precede alternating repetition time steady state free precession (ATR SSFP) pulse sequences to enable image acquisition before reaching a steady-state equilibrium. The design of the preparatory sequences is based on a two step process: First an oscillatory residue is expressed in terms of a window (e.g., a Kaiser-Bessel window) and scale parameters. Second the oscillatory residue is minimized to determine the scale parameters according to a desired application (e.g. ATR SSFP, optimized for fat, water, etc.) The preparation scheme described in this specification can be applied to arbitrary repetition times and RF phase cycling combinations.
    Type: Application
    Filed: March 2, 2009
    Publication date: October 15, 2009
    Applicant: UNIVERSITY OF SOUTHERN CALIFORNIA
    Inventors: Hsu-Lei Lee, Krishna S. Nayak
  • Patent number: 7446526
    Abstract: For in vivo magnetic resonance imaging at high field (?3 T) it is essential to consider the homogeneity of the active B1 field (B1+), particularly if surface coils are used for RF transmission. A new method is presented for highly rapid B1+ magnitude mapping. It combines the double angle method with a B1-insensitive magnetization-reset sequence such that the choice of repetition time (TR) is independent of T1 and with a multi-slice segmented (spiral) acquisition to achieve volumetric coverage with adequate spatial resolution in a few seconds.
    Type: Grant
    Filed: December 21, 2006
    Date of Patent: November 4, 2008
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Charles H. Cunningham, Krishna S. Nayak, John M. Pauly
  • Publication number: 20080150528
    Abstract: For in vivo magnetic resonance imaging at high field (?3 T) it is essential to consider the homogeneity of the active B1 field (B1+), particularly if surface coils are used for RF transmission. A new method is presented for highly rapid B1+ magnitude mapping. It combines the double angle method with a B1-insensitive magnetization-reset sequence such that the choice of repetition time (TR) is independent of T1 and with a multi-slice segmented (spiral) acquisition to achieve volumetric coverage with adequate spatial resolution in a few seconds.
    Type: Application
    Filed: December 21, 2006
    Publication date: June 26, 2008
    Applicant: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Charles H. Cunningham, Krishna S. Nayak, John M. Pauly