Determine Fluid Flow Rate Patents (Class 324/306)
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Publication number: 20080084206Abstract: With the objective of easily drawing a flow such as a bloodstream in a subject at low luminance, there is provided a magnetic resonance imaging apparatus including a static magnetic field forming unit, a transmission unit which transmits a plurality of inversion RF pulses to a subject lying in a static magnetic field plural times within one repetition time after transmission of one excitation RF pulse thereby to excite spins of the subject, a gradient magnetic field application unit, a data acquisition unit which acquires magnetic resonance signals encoded by the gradient magnetic field, and an image generation unit which generates an image of the subject based on the magnetic resonance signals acquired by the data acquisition unit. The gradient magnetic field application unit applies velocity encode gradient pulses inverted to one another in polarity to the subject within transmission interval times for the plural RF pulses transmitted to the subject.Type: ApplicationFiled: October 3, 2007Publication date: April 10, 2008Inventor: Mitsuharu Miyoshi
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Patent number: 7343193Abstract: A 3D projection reconstruction pulse sequence is employed during a CEMRA dynamic study to acquire a time course series of k-space data sets. Signals from non-vascular voxels are suppressed by reconstructing a corresponding series of low resolution images using the centers of the acquired k-space data sets, and measuring the degree to which the signal behavior of voxels therein differ from a model of unwanted signal. Signals from voxels which do not differ from the model are suppressed and the resulting filtered low resolution images are transformed back to k-space and combined with the originally acquired peripheral k-space data to form complete, filtered k-space data sets from which images may be reconstructed.Type: GrantFiled: February 5, 2004Date of Patent: March 11, 2008Assignee: Wisconsin Alumni Research FoundationInventors: Walter Block, Arjun Arunachalam
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Patent number: 7336072Abstract: In a method for representation of flow in a magnetic resonance image, a first magnetic resonance image of an examination subject is acquired, wherein the flow occurring in the examination subject is not compensated in a first spatial direction; a second magnetic resonance image is acquired, wherein the flow occurring in the first spatial direction is compensated, the phase of the magnetization in each of the first and the second magnetic resonance images is calculated of the phase difference between the first phase image and the second phase image, which is calculated is a measure for the flow along the first spatial direction. A third magnetic resonance image is acquired, wherein the flow in a second spatial direction perpendicular to the first spatial direction is not compensated, and a fourth magnetic resonance image is acquired, wherein the flow occurring in the second spatial direction is compensated.Type: GrantFiled: February 24, 2006Date of Patent: February 26, 2008Assignee: Siemens AktiengesellschaftInventors: Stefan Assmann, Oliver Schreck
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Patent number: 7333848Abstract: A method and system are disclosed for evaluating symptomatic VBD which uses quantitative hemodynamic assessment in order to identify patients at high risk for stroke and provide appropriate guidance for intervention. Patients with symptomatic VBD may be considered for intervention to provide blood flow augmentation if evidence of sufficient flow compromise is present as defined by specific flow criteria, and treated medically otherwise.Type: GrantFiled: February 2, 2005Date of Patent: February 19, 2008Assignee: Vassol Inc.Inventors: Fady T. Charbel, Fady Charbel, II, Meide Zhao, Anthony Curcio, Sepideh Amin-Hanjani
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Patent number: 7333846Abstract: In a method and a magnetic resonance apparatus for functional imaging, a number of images without and with a designational stimulation of the examination subject are sequentially registered in successive alternation, and an information value that indicates whether the image was registered during a phase with or without stimulation, at least one image-related stimulation value, and at least one image-related evaluation correlation value are obtained and stored for every image.Type: GrantFiled: February 5, 2002Date of Patent: February 19, 2008Assignee: Siemens AktiengesellschaftInventor: Oliver Schreck
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Patent number: 7317940Abstract: In a method for automatic determination of the actual speed interval of a flowing medium in flow measurements in magnetic resonance imaging, an overview image (localizer) is acquired displayed on a screen, a scout flow measurement is performed by acquiring an image series during a motion cycle at a pre-determined speed interval in a tissue-area to be measured, the peak speed of the medium in the tissue area to be measured is determined on the basis of the scout flow measurement, an optimized flow measurement is performed by acquiring the same images from the acquired image series on the basis of the determined peak speed, and the speed-resolved tissue area obtained by means of the optimized flow measurement is displayed on the screen.Type: GrantFiled: December 2, 2003Date of Patent: January 8, 2008Assignee: Siemens AktiengesellschaftInventor: Stefan Assmann
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Patent number: 7315756Abstract: A multi-slice double inversion recovery (DIR) pulse sequence with read out of a signal for imaging successive slices implemented on a magnetic resonance image scanner. In the method, when the DIR pulse sequence is applied before imaging each slice, a slab-selective inversion re-inverts the entire slab that includes all of the slices. All slices are imaged within a predefined repetition time (TR). The number, N, of slices acquired per TR controls the inversion time to execute the read out of the signal for imaging each slice at a zero-crossing point of blood. In a test, multi-slice DIR images of carotid arteries were obtained with N ranging from 2-8, for four subjects. The results were compared with those for both standard single-slice DIR, and inflow saturation techniques. Multi-slice DIR with N=2-6 provided blood flow suppression in carotid arteries similar to that of single-slice DIR, and significantly better than inflow saturation.Type: GrantFiled: February 27, 2004Date of Patent: January 1, 2008Assignee: University of WashingtonInventors: Vasily L. Yarnykh, Chun Yuan
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Patent number: 7313428Abstract: The present invention is a technique of, and system for, imaging vascular anatomy over distance considerably greater than the maximum practical field of view of a magnetic resonance imaging system while using substantially one contrast agent injection. The technique and system of the present invention acquires image data of a plurality of image volumes which are representative of different portions of the patient's body. The image data of each image volume includes image data which is representative of the center of k-space. The acquisition of image data which is representative of the center of k-space is correlated with a concentration of contrast agent in the artery(ies) residing in the image volume being substantially greater than the concentration of contrast agent in veins and background tissue adjacent to the artery(ies).Type: GrantFiled: December 3, 2004Date of Patent: December 25, 2007Inventors: James F. M. Meaney, Martin R. Prince
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Patent number: 7308298Abstract: A magnetic resonance imaging technique provides adequate MT effects by applying a shortened MT pulse and scan time. An MT pulse whose frequency is off-resonance to a region to be imaged of an object is first applied to he object, a spoiler pulse is applied to the object, and an echo signal is acquired from the region to be imaged. The duration of the MT pulse is set to a relatively shorter time than conventional. Preferably, the duration is less than 10 ms. The area of the MT pulse waveform is set to a specified value equivalent to the conventional. The MT pulse is preferably applicable to a two-dimensional scan using the multislice technique but can also be used in a three-dimensional scan.Type: GrantFiled: December 21, 2001Date of Patent: December 11, 2007Assignee: Kabushiki Kaisha ToshibaInventor: Mitsue Miyazaki
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Patent number: 7298142Abstract: A method and apparatus for obtaining a parameter of interest relating to a region proximate a nuclear magnetic resonance (NMR) logging tool suitable for subterranean well logging is disclosed. The nuclei of the region are subjected to a pulsed NMR technique and are productive of NMR logging data, the nuclei of the region characteristically having a longitudinal relaxation time T1 distribution and an apparent transverse relaxation time T2app distribution. In response to the NMR logging data, an R distribution is defined as R=T1/T2app, the T2app and R distributions are processed as separate bins, along with the NMR logging data, according to a two-dimensional inversion model, and a signal intensity map of R versus T2app is provided that is representative of the parameter of interest relating to the region. In response to a high-intensity signal on the map being within a first range of T2app values and a first range of R values, the presence of a light hydrocarbon within the region is identified.Type: GrantFiled: June 27, 2005Date of Patent: November 20, 2007Assignee: Baker Hughes IncorporatedInventors: Gabor G. Hursan, Songhua Chen
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Patent number: 7295006Abstract: Disclosed are a method and apparatus for accurately measuring nuclear magnetic resonance (NMR) longitudinal axis relaxation time by minimizing the influence of the amount of blood. The method includes applying a first magnetic field MO to a living body portion into which the blood flows magnetizing the blood in a first direction; applying a second magnetic field MZ to at least a portion of the living body portion, to which the first magnetic field MO is applied, magnetizing at least a portion of the blood in a second direction vertical to the first direction;; blocking MZ detecting a signal that is induced as magnetization is returned from the second direction to the first direction; detecting the amount of blood to which the second magnetic field MZ is applied; and calculating the longitudinal axis relaxation time T1 of the blood based on the induced signal and based on the amount of blood.Type: GrantFiled: April 21, 2006Date of Patent: November 13, 2007Assignee: Samsung Electronics Co., Ltd.Inventors: Sergey Potapov, Jong-hwa Won
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Patent number: 7292032Abstract: An automated image processing technique is disclosed that evaluates pixels of a phase-difference image to determine those pixels corresponding to inflowing phase data and background phase data. Phase-difference images are generated from a first acquisition and a second acquisition. Non-zero spatially varying background phase from the phase-difference images that are due to eddy currents induced by flow encoding gradients used to generate the phase-difference images is determined. This non-zero spatially varying background phase is removed from the phase-difference images to determine phase associated with flowing spins and phase associated with stationary spins.Type: GrantFiled: September 28, 2004Date of Patent: November 6, 2007Assignee: General Electric CompanyInventor: Jason A. Polzin
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Publication number: 20070247150Abstract: An fMRI study is conducted using a 2D EPI pulse sequence. A separate blood flow navigator pulse sequence is interleaved with the fMRI data acquisition to monitor blood flow in arteries that feed the brain tissue. Information in the blood flow navigator data is used to reduce errors in the fMRI data due to tissue motion caused by pulsatile blood flow. In one embodiment the blood flow navigator information is used to gate the fMRI acquisition and in another embodiment the information is used to retrospectively correct acquired fMRI data.Type: ApplicationFiled: April 16, 2007Publication date: October 25, 2007Inventor: Andre van der Kouwe
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Patent number: 7283862Abstract: The present invention includes a method and apparatus to perform rapid multi-slice MR imaging without ECG gating or requiring breath-holding that is capable of renal profusion analysis and angiographic screening. An ungated interleaved pulse sequence is applied in rapid succession, followed by a delay interval. The ungated interleaved pulse sequence is repeatedly played out with the predefined delay interval between each application of the pulse sequence. The resulting images provide not only a series of temporal phases of contrast-enhanced blood uptake for renal profusion analysis, but also provide enough dynamic range to include angiographic screening of the renal arteries.Type: GrantFiled: May 16, 2002Date of Patent: October 16, 2007Assignee: General Electric CompanyInventors: Glenn S. Slavin, Thomas K. F. Foo
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Publication number: 20070222451Abstract: An apparatus for shimming the magnetic field generated by a magnet arrangement of a magnetic resonance imaging (MRI) system, has a number of shim devices of substantially similar cross-sectional dimensions, at least some of the shim devices exhibiting differing ferromagnetic characteristics. A structure body has an elongate, tubular channel cross-sectionally dimensioned to serially receive the shim devices in a predetermined sequence to provide a required distribution of the ferromagnetic characteristics in relation to said magnetic field, the channel being of length sufficient to accommodate the shim devices serially in said predetermined sequence. The shim devices are presented at the entrance of the channel in the sequence, and are forced into the channel in the sequence by pressurized fluid directed toward the entrance.Type: ApplicationFiled: February 22, 2007Publication date: September 27, 2007Inventors: Stuart Paul Feltham, Matthew Hobbs, Marcel Jan Marie Kruip
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Patent number: 7268552Abstract: A Toroid Cavity Detector (TCD) is provided for implementing nuclear magnetic resonance (NMR) studies of chemical reactions under conditions of high pressures and temperatures. A toroid cavity contains an elongated central conductor extending within the toroid cavity. The toroid cavity and central conductor generate an RF magnetic field for NMR analysis. A flow-through capillary sample container is located within the toroid cavity adjacent to the central conductor to subject a sample material flowing through the capillary to a static magnetic field and to enable NMR spectra to be recorded of the material in the capillary under a temperature and high pressure environment.Type: GrantFiled: June 21, 2005Date of Patent: September 11, 2007Assignee: United States of America as represented by the United States Department of EnergyInventors: Rex E. Gerald, II, Michael J. Chen, Robert J. Klingler, Jerome W. Rathke, Marc ter Horst
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Patent number: 7268547Abstract: An apparatus and method for compensating for the effect of tool motion in NMR MWD measurements. Signals obtained from a directionally sensitive receiver are compensated for the effects of tool motion. In an alternative embodiment, directional transmitters and receivers are used, with the pulsing of the transmitter controlled by the output of motion sensors. In another embodiment, the transmitters and receivers may be axisymmetric and the received signals are corrected using results of a NMR simulation program that takes account of the recorded motion of the apparatus.Type: GrantFiled: October 5, 2004Date of Patent: September 11, 2007Assignee: Baker Hughes IncorporatedInventors: Thomas Kruspe, Martin Blanz
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Patent number: 7265544Abstract: A method and device for obtaining an interference free measurement from a flowmeter. The flowmeter includes a measuring tube through which a flowable medium flows through a magnetic field generated by a magnetic arrangement and at least two measuring electrodes for detecting the measurement voltage induced by the flowable medium. The medium gives rise to interference voltages. The electrodes are connected to an interference-voltage eliminating unit by which common-mode interference is first eliminated by differentiation and unequal interference voltages are subsequently eliminated.Type: GrantFiled: July 14, 2006Date of Patent: September 4, 2007Assignee: ABB patent GmbHInventors: Dieter Keese, Thomas-Fritz Blume, Dirk Steckel
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Patent number: 7259558Abstract: A method of nuclear magnetic resonance (NMR) imaging is proposed for the rapid detection of oscillatory motion of spins or charged particles to generate shear waves or oscillating electrical currents to induce alternating magnetic fields to the object being imaged, subjected to a fast train of radio-frequency (RF) pulses to induce within the sample a steady-state NMR signal. A scan using an NMR imaging system is carried out with a RF repetition time (TR) matched to the externally imposed oscillatory motion. Small oscillatory displacements of spins in combination with imaging gradients or oscillating magnetic fields related to charge motion generating alternating spin phase dispersions during the rf pulse train disturb the steady-state magnetization.Type: GrantFiled: December 19, 2005Date of Patent: August 21, 2007Assignee: University of BaselInventors: Oliver Bieri, Klaus Scheffler
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Patent number: 7256578Abstract: A magnetic resonance imaging system includes a high-frequency magnetic field generating unit for generating and applying a high-frequency magnetic field to a subject placed in a static magnetic field, a gradient magnetic field generating unit for generating a gradient magnetic field to be superimposed on the static magnetic field, and a sequencer for controlling the high-frequency magnetic field generating unit and the gradient magnetic field generating unit to acquire, within a specified part of the heartbeat of the subject, MR data that pertains to a plane through which an axis substantially identical to the body axis of the subject in a k-space extends, and to cause the plane to rotate, at every heartbeat, about the axis substantially identical to the body axis.Type: GrantFiled: March 2, 2007Date of Patent: August 14, 2007Assignee: Keio UniversityInventor: Koichi Oshio
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Patent number: 7218104Abstract: Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.Type: GrantFiled: September 25, 2006Date of Patent: May 15, 2007Inventors: John Clarke, Robert McDermott, Alexander Pines, Andreas Heinz Trabesinger
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Patent number: 7215119Abstract: In a method for dynamic frequency detection of the resonance frequency in magnetic resonance spectroscopy, by measuring navigator signals at the same point in time in each of a number of successive sequence passes, and by comparing the navigator signals, a frequency shift of the resonance frequency is determined on the basis of which the respective individual spectrum obtained from each sequence repetition is corrected with respect to the measured frequency shift.Type: GrantFiled: April 29, 2005Date of Patent: May 8, 2007Assignee: Siemens AktiengesellschaftInventors: Gunnar Krüger, Stefan Röll
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Movement-corrected multi-shot method for diffusion-weighted imaging in magnetic resonance tomography
Patent number: 7205763Abstract: In a multi-shot method for diffusion-weighted imaging in magnetic resonance tomography, the sampling of the k-matrix in the readout direction ensues in segments, and immediately after acquisition of an image data set by readout of one segment by means of echo signals, a navigation data set is acquired by readout of the middle region of the k-matrix at virtually the same time. A movement-corrected diffusion-weighted MRT image is generated by combining of the image data sets with the corresponding navigation data sets and subsequent Fourier transformation.Type: GrantFiled: April 13, 2005Date of Patent: April 17, 2007Assignee: Siemens AktiengesellschaftInventor: David Andrew Porter -
Patent number: 7202662Abstract: Errors in qualitative phase contrast measurements due to gradient field heterogeneities are reduced by using either a generalized reconstruction algorithm or an approximate reconstruction algorithm. True velocities are calculated using measured velocity information and phase differences, first moments of gradients, and gyromagnetic ratio.Type: GrantFiled: June 16, 2003Date of Patent: April 10, 2007Assignee: The Board of Trustees of the Leland Stanford Junior UniversityInventors: Michael Markl, Norbert J. Pelc, Roland Bammer
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Patent number: 7196517Abstract: A method for evaluating formation fluids includes measuring a nuclear magnetic resonance property related to a total volume of the formation fluids, measuring a dielectric property related to an electromagnetic wave travel time, measuring a bulk density, and solving a set of linear response equations representing a reservoir fluid model to determine fractional fluid volumes from the nuclear magnetic resonance property, the dielectric property, and the bulk density.Type: GrantFiled: March 30, 2006Date of Patent: March 27, 2007Assignee: Schlumberger Technology CorporationInventor: Robert Freedman
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Patent number: 7197353Abstract: A sensitivity encoding method (SENSE) is used to acquire an MR image having a reduced field of view. The number of aliased replicates caused by surrounding object boundaries is calculated for each image pixel location to obtain optimal aliasing artifact suppression without reducing image SNR.Type: GrantFiled: September 14, 2001Date of Patent: March 27, 2007Assignee: General Electric CompanyInventors: Kevin F. King, Lisa C. Angelos
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Patent number: 7187791Abstract: For a purpose of improving homogeneity of an image obtained in a self-calibration by a parallel imaging method generally referred to as SENSE (SENSitivity Encoding), sensitivity factors Sn(p) are calculated using an additive image Ab=?|Cn| of complex images Cn obtained by conducting a calibration scan of an entire FOV for phased array coils Coil_n (n=1–N, N?2) (Steps V2, V3). Moreover, sensitivity maps Sn are generated by conducting curve fitting by the method of least squares weighted by the square of a pixel value Ab(p) of the absolute value additive image Ab (Step V4).Type: GrantFiled: June 4, 2003Date of Patent: March 6, 2007Assignee: GE Medical Systems Global Technology Company, LLCInventor: Yoshikazu Ikezaki
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Patent number: 7167740Abstract: In a measuring space of the object (1), an essential measurement region (41, 61, 71, 81, 111, 131) having a center region of the measuring space and a plurality of peripheral measurement regions (42, 62, 63, 72, 82, 112, 132) which do not have any region overlapped with the essential measurement region are set. Then, the essential measurement region is combined with a selected peripheral portion of the plurality of the peripheral measurement regions to measure in a preceding manner a nuclear magnetic resonance signal from the object as data of the measuring space. The essential measurement region is combined with the peripheral measurement region of the plurality of the peripheral measurement regions which has not been selected in the preceding measuring step to measure a nuclear magnetic resonance signal from the object as data of the measuring space.Type: GrantFiled: December 3, 2001Date of Patent: January 23, 2007Assignee: Hitachi Medical CorporationInventors: Takayuki Abe, Shigeru Watanabe, Hirotaka Takeshima
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Patent number: 7164123Abstract: A method for filtering spurious resonances from an NMR dataset comprises the steps of: (a) creating a first, non-oscillating magnetic field of a predetermined field strength across a sample, (b) intermittently exposing the sample to a second, oscillating magnetic field orthogonal to the first to generate an NMR signal, (c) detecting the NMR signal from the sample, (d) adjusting the first magnetic field to a different predetermined field strength and repeating steps (a) to (c), and (d) comparing the detected signals to obtain an NMR dataset from the sample from which spurious resonances have been filtered.Type: GrantFiled: December 28, 2005Date of Patent: January 16, 2007Assignee: Rolls-Royce plcInventors: Peter G. Morris, Terry Moore, Paul Anuzis, Kenneth Astley
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Patent number: 7145334Abstract: In a method and MR apparatus for the automatic segmentation of flow images acquired by magnetic resonance tomography for the depiction of tissue or organs traversed with fluid such as blood, at least one phase image of a selected region of the subject is acquired by magnetic resonance tomography, and fluid-traversed regions in the at least one phase image are automatically segmented.Type: GrantFiled: November 24, 2004Date of Patent: December 5, 2006Assignee: Siemens AktiengesellschaftInventors: Stefan Assmann, Martin Requardt, Ingo Schmitjans, Oliver Schreck
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Patent number: 7141978Abstract: An NMR system comprises an NMR probe comprising multiple NMR detection sites. Each of the multiple NMR detection sites comprises a sample holding void and an associated NMR microcoil. The NMR system further comprises a controllable fluid router operative to direct fluid sample to the multiple NMR detection sites.Type: GrantFiled: July 14, 2005Date of Patent: November 28, 2006Assignee: Protasis CorporationInventors: Tim L. Peck, Dean Olson, Jim Norcross, David Strand, Jonathan Sweedler
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Patent number: 7116102Abstract: Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.Type: GrantFiled: March 27, 2006Date of Patent: October 3, 2006Assignee: The Regents of the University of CaliforniaInventors: John Clarke, Robert McDermott, Alexander Pines, Andreas Heinz Trabesinger
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Patent number: 7096056Abstract: A method for functional magnetic resonance imaging (fMRI) uses steady-state free precession (SSFP) to image changes in blood oxygenation between two time periods. A center frequency of the SSFP sequence is placed between the different resonant frequencies for oxyhemoglobin and deoxyhemoglobin whereby the signals have a phase difference of 180° and tend to cancel. By repeating the SSFP imaging sequence at different times, the difference in the measured signals provides a measure of change in oxyhemoglobin. RF flip angle of the SSFP sequence is chosen to maximize signal level in the frequency range from that of water in the presence of oxyhemoglobin and that of water in the presence of deoxyhemoglobin.Type: GrantFiled: June 16, 2003Date of Patent: August 22, 2006Assignee: The Board of Trustees of the Leland Stanford Junior UniversityInventors: Karla L. Miller, John M. Pauly
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Patent number: 7078897Abstract: An MR method and system of determining elements of the apparent diffusion coefficient tensor in a material with plurality of anisotropic structural units that can be too small to be resolved by direct imaging. MR data is acquired with MR system including pulse sequences, the sequences including imaging or spectroscopy pulse sequences with a series of embedded diffusion-sensitizing gradient waveforms with different gradient strength applied to the material. A nonlinear function of a b-value corresponding to the pulse sequence is defined and the acquired MR data is processed according to defined nonlinear function. Images/maps of the components of the tensor of apparent diffusion coefficients, corresponding to anisotropic structural units, based on the processed MR data, are created. A method of evaluating of the geometrical parameters of lung airways is also described.Type: GrantFiled: January 15, 2003Date of Patent: July 18, 2006Assignee: Washington UniversityInventors: Dmitriy A. Yablonskiy, Alexander L. Sukstanskii, Mark S. Conradi
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Combining NMR, density, and dielectric measurements for determining downhole reservoir fluid volumes
Patent number: 7075297Abstract: A method for evaluating formation fluids includes measuring a nuclear magnetic resonance property related to a total volume of the formation fluids, measuring a dielectric property related to an electromagnetic wave travel time, measuring a bulk density, and solving a set of linear response equations representing a reservoir fluid model to determine fractional fluid volumes from the nuclear magnetic resonance property, the dielectric property, and the bulk density.Type: GrantFiled: August 9, 2002Date of Patent: July 11, 2006Assignee: Schlumberger Technology CorporationInventor: Robert Freedman -
Patent number: 7053610Abstract: Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.Type: GrantFiled: November 22, 2004Date of Patent: May 30, 2006Assignee: The Regents of th University of CaliforniaInventors: John Clarke, Robert McDermott, Alexander Pines, Andreas Heinz Trabesinger
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Patent number: 7049815Abstract: Pulse sequences are applied to a fluid in an earth formation in a static magnetic field having internal gradients. From the received signals, relaxation and diffusion characteristics of the fluid are determined. The determination takes into account the internal field gradients.Type: GrantFiled: January 27, 2004Date of Patent: May 23, 2006Assignee: Baker Hughes IncorporatedInventors: Gregory Itskovich, Arcady Reiderman
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Patent number: 7049816Abstract: A phase contrast image is produced using a 3D projection reconstruction pulse sequence. A high velocity-to-noise image is produced by using a LOW VENC motion encoding gradient. Phase wrap errors caused by high velocity flow is corrected using phase information in a HIGH VENC image produced from highly undersampled data acquired during the same scan.Type: GrantFiled: September 30, 2004Date of Patent: May 23, 2006Assignee: Wisconsin Alumni Research FoundationInventors: Charles A. Mistretta, Kevin Michael Johnson, Tianliang Gu
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Patent number: 7046004Abstract: A method of steady-state free precession MR imaging is provided that includes the steps of: (a) providing a balanced steady-state free precession imaging sequence that includes a plurality of phase encoding steps, wherein each phase encoding step comprises a phase encoding gradient and a slice selection gradient; and (b) acquiring imaging data by performing the plurality of phase encoding steps in sequence, wherein the imaging data is acquired is compensated for one or more effects due to eddy-currents, flow, or motion related artefacts due to the implementation of one or more artefact compensation strategies that consist of (i) “pairing” of consecutive phase encoding steps and of (ii) “through slice equilibration” of eddy-current and motion or flow related signal oscillations.Type: GrantFiled: May 6, 2005Date of Patent: May 16, 2006Assignee: University of BaselInventors: Oliver Bieri, Klaus Scheffler
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Patent number: 7047062Abstract: Disclosed herein is a system and method for decreasing gradient field pulse sequence duration and reducing peripheral nerve stimulation with known gradient pulse areas for a magnetic resonance imaging system. The method comprising: receiving a first desired area corresponding to a first pulse; obtaining a second desired area corresponding to a second pulse; selecting the first pulse as a nested pulse if the first desired area is smaller than the second desired area, and establishing the second pulse as a nesting pulse, otherwise selecting the second pulse as the nested pulse and establishing the first pulse as the nesting pulse. The method also includes: determining an amplitude and pulse duration for the nested pulse and ascertaining an amplitude and pulse duration for the nesting pulse. Finally, the method includes arranging a plurality of gradient field pulse sequences to include the nested pulse and the nesting pulse.Type: GrantFiled: May 16, 2002Date of Patent: May 16, 2006Assignee: GE Medical Systems Global Technology Company, LLCInventors: Paul E. Licato, Steven Wolff
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Patent number: 7009393Abstract: The invention relates to a nuclear magnetic resonance method of detecting and monitoring the flocculation kinetics of high molecular weight fractions of a complex fluid. The inventive method applies the following to the fluid: a first static polarization magnetic field and, subsequently, at least a second oscillating pulsed magnetic field which generates a nuclear magnetic resonance for the nuclei considered and the acquisition of relaxation signals from the nuclei in the fluid. Moreover, the method detects, in the relaxation signals, a first part P1 which is representative of the relaxation of the flocculated fractions in the fluid and a second part P2 which is representative of the relaxation of the liquid fraction of the fluid; and determines the flocculation rate of the fractions by comparison with values M<sb>x</sb>(t=0) and M<sb>x1</sb>(t=0) which were extrapolated at the start of the acquisition times of the two parts.Type: GrantFiled: January 16, 2003Date of Patent: March 7, 2006Assignee: Institut Francais du PetroleInventors: Jean-Pierre Cohen Addad, Marc Fleury
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Patent number: 7003343Abstract: Current bolus chase magnetic resonance angiography is limited by the imaging time for each station. Tailoring the density of k-space sampling along the anterior-posterior direction of the coronal station allows a substantial decrease in scan time that leads to greater contrast bolus sharing among stations and consequently a significant improvement in image quality. Fast arterial-venous transit in the carotid arteries requires accurate, reliable timing of the acquisition to the bolus transit to maximize arterial signal and minimize venous artifacts. The rising edge of the bolus is not utilized in conventional elliptical-centric view ordering because the critical k-space center must be acquired with full arterial enhancement. The invention provides a recessed elliptical-centric view ordering scheme is introduced in which the k-space center is acquired a few seconds following scan initiation. The recessed view ordering is shown to be more robust to timing errors in a patient studies.Type: GrantFiled: April 1, 2002Date of Patent: February 21, 2006Assignee: Cornell Research Foundation, Inc.Inventors: Richard Watts, Yi Wang, Martin R. Prince
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Chemical species suppression for MRI imaging using spiral trajectories with off-resonance correction
Patent number: 6995560Abstract: A method of chemical species suppression for MRI imaging of a scanned object region including acquiring K space data at a first TE, acquiring K space data at a second TE, reconstructing images having off resonance effects, estimating off resonance effects at locations throughout the reconstructed image, and determining the first and second chemical species signals at image locations of the scanned object from the acquired signals and correcting for blurring resulting from off resonance effects due to B0 inhomogeneity.Type: GrantFiled: March 22, 2004Date of Patent: February 7, 2006Inventors: Jeffrey L. Duerk, Jonathan S. Lewin, Hisamoto Moriguchi -
Patent number: 6992483Abstract: The present invention provides a system and method of removing heat from an MR imaging device while maintaining internal and external temperatures below maximum operating limits, thereby enabling higher power applications for faster imaging with improved image quality as well as, allowing longer scan times for interventional procedures. The system includes a vacuum chamber housing the gradient coils and a vacuum pump connected thereto to regulate the pressure and humidity within the chamber. A heat exchanger, coolant pump, and controller are provided to regulate the temperature of coolant designed to dissipate heat from the gradient coils in response to at least one temperature sensor.Type: GrantFiled: March 24, 2005Date of Patent: January 31, 2006Assignee: General Electric CompanyInventors: Pierre R. Emeric, Carl R. Hedlund
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Patent number: 6987997Abstract: A technique is set forth for MR spectroscopy that is capable of reducing signal overlap between metabolite signals for improved clinical analysis of metabolite content. The technique includes varying an echo time across a scanning dimension. Once a span of echo time for an acquisition dimension is determined, and the number of acquisition data points is known, a variance between echo times can be determined. A pulse sequence with differing echo times is then applied for each frame, and after data is acquired, an image is reconstructed that significantly improves metabolite signal separation.Type: GrantFiled: June 18, 2003Date of Patent: January 17, 2006Assignee: General Electric CompanyInventors: Ralph E. Hurd, Napapon Sailasuta
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Patent number: 6985766Abstract: The invention refers to an apparatus for positioning medical treatment devices or treatment supporting devices (2) by a transportation means (1) to move said devices (2) to a predetermined position, said transportation means (1) including an automatically guided transport system (3, 7), and to a corresponding method and the use of an automatically guided transport system to perform said positioning tasks.Type: GrantFiled: January 26, 2001Date of Patent: January 10, 2006Assignee: BrainLAB AGInventors: Richard Braun, Robert Schmidt
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Patent number: 6980845Abstract: This invention is a method for multi-slice CBF imaging using continuous arterial spin labeling (CASL) with an amplitude modulated control which is both highly effective at controlling for off resonance effects, and efficient at doubly inverting inflow spins, thus retaining the signal advantages of CASL versus pulsed ASL techniques.Type: GrantFiled: April 13, 1999Date of Patent: December 27, 2005Assignee: The Trustees Of The University Of PennsylvaniaInventor: David C. Alsop
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Patent number: 6972564Abstract: An objective oriented NMR logging method selects pulse sequences over a plurality of frequencies from a set of building blocks. The building blocks include trainlet sequences wherein each trainlet comprises an excitation pulse and a plurality of refocusing pulses, the total length of a trainlet being typically less than 10 ms. Another building block is a short CPMG or modified CPMG sequence and yet another building block is a regular CPMG or modified CPMG sequence. The modified CPMG sequences may have refocusing pulses with a tipping angle less than 180° to reduce the power consumption. Based on the logging objective (formation evaluation or FE, FE plus hydrocarbon typing, FE plus gas evaluation) the building blocks are combined at a plurality of frequencies with different wait times and TEs.Type: GrantFiled: November 5, 2002Date of Patent: December 6, 2005Assignee: Baker Hughes IncorporatedInventors: Songhua Chen, Carl M. Edwards
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Patent number: 6963199Abstract: A rare gas polarizer apparatus includes a polarizing section for bringing a rare gas contained in a mixed gas to a hyperpolarized state, an extracting section for sublimating the rare gas from the mixed gas, extracting the rare gas as a solid, and vaporizing the extracted solid rare gas, and a supplying section for mixing the vaporized rare gas with an inspired material, and supplying the gas to a mask section that is closed against the outer air and covering the respiratory organs of the subject.Type: GrantFiled: June 30, 2004Date of Patent: November 8, 2005Assignee: GE Medical Systems Global Technology Company, LLCInventor: Hiroshi Sato
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Patent number: 6958605Abstract: A method and system of correcting for a motion of an object are provided. In these system and method, the navigator data and map data are first obtained for the object. Then, the navigator data is compared with the map data to generate comparison data. Thereafter, a translation and/or a rotation of the object is corrected in real time as a function of the comparison data. The navigator can be preferably an octant navigator and/or a clover leaf navigator. In one exemplary embodiment, a scanning sequence can be used to determine a position of the object. This scanning sequence may include a signal portion which includes at least one radio frequency signal, a navigator portion which includes at least one octant navigator or one clover leaf navigator, and a spoiler portion provided for reducing a signal magnitude of the scanning sequence. The navigator is provided for allowing a measurement of at least one of the rotation and translation of the object.Type: GrantFiled: May 14, 2004Date of Patent: October 25, 2005Assignee: The General Hospital CorporationInventors: Anders M. Dale, Andre J. W. Van Der Kouwe