Patent application number | Description | Published |
20080231282 | On-coil switched mode amplifier for parallel transmission in MRI - Example systems, apparatus, circuits, and so on described herein concern parallel transmission in MRI. One example apparatus includes at least two field effect transistors (FETs) that are connected by a coil that includes an LC (inductance-capacitance) leg. The apparatus includes a controller that inputs a digital signal to the FETs to control the production of an output analog radio frequency (RF) signal. The LC leg is to selectively alter the output analog RF signal and the analog RF signal is used in parallel magnetic resonance imaging (MRI) transmission. | 09-25-2008 |
20080278160 | Dynamic pMRI using GRAPPA-operator - Example systems, methods, and apparatus facilitate providing a k-space line that is missing in an under-sampled time frame. The missing line is computed by applying a GRAPPA-operator to a known k-space line in the under-sampled time frame. One example method includes controlling a dynamic parallel magnetic resonance imaging (DpMRI) apparatus to acquire a first under-sampled time interleaved frame having at least one first k-space line and controlling the DpMRI apparatus to acquire a second under-sampled time interleaved frame having at least one second k-space line that neighbors the first k-space line. The method includes assembling a reference data set from the first under-sampled time frame and the second under-sampled time frame and then determining the GRAPPA-operator from neighboring k-space lines in the reference data set. | 11-13-2008 |
20080278161 | Conjugate symmetry in parallel imaging - Example systems, methods, and apparatus associated with conjugate symmetry in parallel imaging are provided. One example method includes controlling a parallel magnetic resonance imaging (pMRI) apparatus to acquire a first magnetic resonance (MR) signal from a first point in k-space using a phased array of receiving coils. The method also includes identifying a second point in k-space that is related to the first point by a conjugate symmetry relation. The relation may be, for example, a reflection, a rotation, and so on. The method also includes determining a second MR signal associated with the second point based, at least in part, on the first MR signal and the conjugate symmetry relation and then reconstructing an MR image based, at least in part, on both the first MR signal and the second MR signal. | 11-13-2008 |
20080278162 | Cartesian continuous sampling with unequal gradients - Example methods and apparatus control ratios between a maximum gradient amplitude (MGA) of a readout lobe (G | 11-13-2008 |
20080290868 | Determining phase-encoding direction for parallel MRI - Example systems, methods, and apparatus associated with determining a phase-encoding direction for parallel MRI are described. One example, method includes selecting a set of projection directions along which an MRI apparatus is to apply RF energy to an object to be imaged. The method includes controlling the MRI apparatus to selecting a set of projection directions and to acquire MR signal from the object through a set of detectors. The method includes analyzing the MR signal to identify individual sensitivities for members of the set of detectors and selecting a phase-encoding direction for a pMRI session based on the individual sensitivities for the members. The method produces a concrete, tangible, and useful result by controlling the MRI apparatus to perform the pMRI session based on the selected phase-encoding direction. | 11-27-2008 |
20080309336 | CALIBRATING pMRI WITH CARTESIAN CONTINUOUS SAMPLING - Example systems, methods, and apparatus control a pMRI apparatus to produce a pulse sequence having an extended acquisition window, and overlapping phase-encoding gradients and read gradients. One example method controls a pMRI apparatus to produce a trajectory having Cartesian and radial segments that sample in a manner that satisfies the Nyquist criterion in at least one region of a volume to be imaged. The pMRI apparatus is controlled to apply radio frequency energy to the volume according to the pulse sequence and following the trajectory and to acquire MR signal from the volume in response to the application of the RF energy. The MR signal includes a first component associated with the Cartesian segment of the trajectory and a second component associated with the radial segment of the trajectory. The example method includes calibrating a reconstruction process using Nyquist-satisfying data from the second component. | 12-18-2008 |
20090092303 | Dynamic parallel magnetic resonance imaging(DpMRI) with sparse data - Example methods, apparatus, and systems associated with dynamic parallel magnetic resonance imaging (DpMRI) are presented. One example system facilitates separating data associated with a dynamic portion of a dynamic magnetic resonance image from data associated with a static portion of the dynamic magnetic resonance image. The system computes reconstruction parameters for a DpMRI reconstruction processes for both the dynamic portion of the image and the static portion of the image. The example system produces a DpMRI image based on separate reconstructions of the dynamic portion of a dynamic magnetic resonance image and the static portion of a dynamic magnetic resonance image. The separate reconstructions may depend on separate sets of reconstruction parameters and on separated static data and dynamic data. | 04-09-2009 |
20090134876 | Multi-frequency excitation coils for MRI - Devices, systems, methods, and other embodiments associated with magnetic resonance imaging (MRI) are described. In one embodiment, an apparatus includes an RF coil for use in multi-nuclear excitation in magnetic resonance imaging (MRI). The RF coil includes a set of two or more L-C coils. Members of the set of two or more L-C coils have individual resonance frequencies. An RF amplifier is placed near the RF coil. The RF amplifier is controllable to selectively produce the individual resonance frequency of a member of the set of two or more L-C coils based, at least in part, on a digital input provided to the RF amplifier. | 05-28-2009 |
20090177075 | Resolution enhanced T1-insensitive steady state imaging (RE-TOSSI) - Systems, methods, and other embodiments associated with RE-TOSSI are described. One system embodiment includes an MRI apparatus configured to produce a RE-TOSSI pulse sequence and to acquire T2-weighted images in response to the RE-TOSSI pulse sequence. An example RE-TOSSI pulse sequence includes a TOSSI portion and a non-inverting, non-TOSSI portion. | 07-09-2009 |
20090256571 | MAGNETIC RESONANCE APPARATUS WITH RF AMPLIFIER(S) DISPOSED WITHIN THE SPACED DISTANCE BETWEEN THE PRIMARY AND SECONDARY GRADIENT COIL WINDINGS - An arrangement for controlling an antenna arrangement in a magnetic resonance device has an antenna arrangement that surrounds an examination region and that has at least one antenna element for emitting an amplified transmit signal. At least one amplifier is provided, at the input of which a high-frequency transmit signal is connected, which is present on the output side of the amplifier as an amplified transmit signal. The amplifier is connected to a feed point of the antenna arrangement on the output side, in order to emit the amplified transmit signal. Coil windings of a primary gradient coil are also provided, which at least partially include the antenna arrangement and the examination region. Coil windings of a secondary gradient coil at least partially include the coil windings of the primary gradient coil, the antenna arrangement (and the examination region). The coil windings of the secondary gradient coil and the coil windings of the primary gradient coil are at a distance from one another, in which the at least one amplifier is arranged. | 10-15-2009 |
20090261825 | DARK BLOOD BALANCED STEADY STATE FREE PRECESSION IMAGING - Systems, methods, and other embodiments associated with controlling a magnetic resonance imaging (MRI) apparatus to perform a balanced steady state free precession (bSSFP) technique that includes magnetization preparation with differentiated velocity encoding and spoiling residual transverse magnetization are described. The example systems, methods, and other embodiments are also associated with acquiring a dark blood image in response to the bSSFP technique. A dark blood image is one in which NMR signal acquired from an object subjected to the bSSFP technique and magnetization preparation includes NMR signal from flowing spins and NMR signal from non-flowing spins in a desired ratio. | 10-22-2009 |
20090261827 | MITIGATING SATURATION ARTIFACTS ASSOCIATED WITH INTERSECTING PLANE TRUEFISP ACQUISITIONS THROUGH GROUPED REVERSE CENTRIC PHASE ENCODING - Systems methods, and other embodiments associated with acquiring intersecting TrueFISP images using grouped reverse centric phase encoding are described. One example method includes controlling an MRI apparatus to produce a TrueFISP sequence that delays acquisition of the center of k-space to reduce saturation banding artifacts. The example method also includes controlling the MRI apparatus to produce a TrueFISP sequence that reduces eddy current artifacts by grouping (e.g., pairing) lines in k-space. The method concludes by acquiring NMR signal in response to the TrueFISP sequence. | 10-22-2009 |
20090264736 | DEVICE WITH 3D ARRAY OF STEERING COILS - Systems, methods, and other embodiments associated with remotely controlling a catheter configured with a 3D array of steering coils are described. One example magnetic resonance imaging (MRI) apparatus may include logic to remotely control a catheter. The 3D array of coils may include, for example, one axial coil and two side coils. The MRI apparatus may independently control current provided to members of the 3D array of coils. The MRI apparatus may also selectively produce different pulse sequences to mitigate and/or take advantage of signal voids present in an acquired image due to susceptibility effects from a field(s) generated by a member(s) of the 3D array of coils. Independently controlling the current provided to the 3D array of coils facilitates bending the catheter in a desired position as a result of a magnetic torque associated with a magnetic moment induced in a member of the 3D array of coils. | 10-22-2009 |
20100063380 | Steady state dark blood magnetic resonance imaging - Systems, methods, and other embodiments associated with steady state dark blood magnetic resonance imaging MRI are described. One example method includes controlling an MRI apparatus to produce a steady state pulse sequence. The example method may also include controlling the MRI apparatus to generate radio frequency (RF) energy and magnetic gradients associated with the steady state pulse sequence. The steady state pulse sequence is different from conventional steady state pulses in that it is characterized by regularly spaced slice selection excitation pulses to excite a region to be imaged in an object to be imaged using a consistent repetition time (TR), a set of readout modules, and a set of a magnetization preparation modules. A magnetization preparation module is characterized by gradients associated with imaging not being active, gradients associated with slice selection being active, and RF pulses associated with slice selection being active. | 03-11-2010 |
20100201363 | CALIBRATING PARALLEL MRI WITH CARTESIAN CONTINUOUS SAMPLING - Example systems, methods, and apparatus control a pMRI apparatus to produce a pulse sequence having an extended acquisition window, and overlapping phase-encoding gradients and read gradients. One example method controls a pMRI apparatus to produce a trajectory having Cartesian and non-Cartesian segments that sample in a manner that satisfies the Nyquist criterion in at least one region of a volume to be imaged. The pMRI apparatus is controlled to apply radio frequency energy to the volume according to the pulse sequence and following the trajectory and to acquire MR signal from the volume in response to the application of the RF energy. The MR signal includes a first component associated with the Cartesian segment of the trajectory and a second component associated with the non-Cartesian segment of the trajectory. The example method includes calibrating a reconstruction process using Nyquist-satisfying data from the second component. | 08-12-2010 |
20100225319 | DETERMINING PHASE-ENCODING DIRECTION FOR PARALLEL MRI - Example systems, methods, and apparatus associated with determining a phase-encoding direction for parallel MRI are described. One example, method includes selecting a set of projection directions along which an MRI apparatus is to apply RF energy to an object to be imaged. The method includes controlling the MRI apparatus to selecting a set of projection directions and to acquire MR signal from the object through a set of detectors. The method includes analyzing the MR signal to identify individual sensitivities for members of the set of detectors and selecting a phase-encoding direction for a pMRI session based on the individual sensitivities for the members. The method produces a concrete, tangible, and useful result by controlling the MRI apparatus to perform the pMRI session based on the selected phase-encoding direction. | 09-09-2010 |
20100237862 | Mitigating Off-Resonance Angle In Steady-State Coherent Imaging - Systems, methods, and other embodiments associated with mitigating off-resonance angle in steady-state coherent magnetic resonance imaging (MRI) are described. One example method includes accessing a B0 map and a coil sensitivity profile associated with an MRI apparatus configured to produce a steady-state coherent MRI sequence to image an object. The MRI apparatus is configured with a multi-channel transmission array having individually controllable transmission channels. The method includes computing transmission control parameters for individual transmission channels as a function of the B0 map and the coil sensitivity profile. The transmission control parameters are configured to facilitate controlling the transmission array to create a spatially varying phase profile using a single dimensional radio frequency (RF) pulse. | 09-23-2010 |
20100237869 | Controlling Multi-Channel Transmitter Effects on Specific Absorption Rate - Systems, methods, and other embodiments associated with controlling the specific absorption rate (SAR) in a patient associated with a conductor are described. The conductor may be, for example, a wire associated with a pacemaker, a wire associated with a neurostimulator, an orthopaedic device, and so on. One example method includes calibrating a multi-channel transmitter associated with a magnetic resonance imaging (MRI) apparatus imaging the patient. The example method also includes controlling the MRI apparatus to transmit radio frequency (RF) energy to image the patient in a manner where the RF energy will only influence the SAR near the conductor in the patient less than a desired threshold amount. | 09-23-2010 |
20100239143 | REDUCING ACQUISITION TIME - Systems, methods, apparatus, and other embodiments associated with reducing imaging acquisition time are described. One example method includes accessing an under-sampled data set and a library of previously acquired data sets. The method includes producing an approximation of the under-sampled data set by transforming data stored in the library. The method includes producing a sparsified data set from the approximation and the under-sampled data set and then reconstructing the sparsified data set into a sparse image using a reconstruction technique configured to reconstruct sparse data. The method includes producing a fully-sampled approximation of the under-sampled data set and producing a final reconstructed image from the sparse image and the fully sampled approximation. | 09-23-2010 |
20100241389 | EXCITATION UNIFORMITY - Systems, methods, and other embodiments associated with MRI excitation are described. One example method includes performing a calibration to determine a set of transmission parameters for a set of excitation pulses for transmission channels available on a multi-channel MRI transmitter. The set of excitation pulses are configured to produce a resulting nuclear magnetic resonance (NMR) signal from an object exposed to the set of excitation pulses. The resulting NMR signal comprises NMR signal associated with a first NMR resonance associated with the object and NMR signal associated with a second NMR resonance associated with the object. | 09-23-2010 |
20100253331 | DYNAMICALLY SELECTIVELY CONFIGURING WIRELESS TRANSMITTER ASSOCIATED WITH MRI DETECTOR COIL - Systems, methods, and other embodiments associated with dynamically selectively configuring wireless transmitters associated with MRI detector coils are described. One example apparatus includes a detector coil to receive an NMR signal. The apparatus includes a dynamically configurable transmitter to transmit an RF transmission according to a configurable set of transmission parameters. The RF transmission is based on the NMR signal received by the MRI detector coil. The apparatus includes a tuning logic that cycles between an active state and a passive state under the control of a tuning program. While in the passive state, the tuning logic is to generate substantially no RF that could interfere with receiving the NMR signal at the MRI detector coil. While in the active state, the tuning logic is to configure the dynamically configurable transmitter to transmit according to the set of transmission parameters. | 10-07-2010 |
20110089946 | THROUGH-TIME NON-CARTESIAN GRAPPA CALIBRATION - Example systems and methods control a parallel magnetic resonance imaging (pMRI) apparatus to acquire non-Cartesian (e.g., spiral) calibration data sets throughout time. Example systems and methods also control the pMRI apparatus to acquire an under-sampled non-Cartesian data set from the object to be imaged. Example systems and methods then control the pMRI apparatus to reconstruct an image of the object to be imaged from the under-sampled non-Cartesian data set. The reconstruction depends, at least in part, on a through-time non-Cartesian GRAPPA calibration where a value for a point missing from k-space in the under-sampled non-Cartesian data set is computed using a GRAPPA weight set calibrated and applied for the missing point. The GRAPPA weight set is computed from data in the non-Cartesian calibration data sets. | 04-21-2011 |
20110093233 | THROUGH-TIME RADIAL GRAPPA CALIBRATION - Example systems and methods control a parallel magnetic resonance imaging (pMRI) apparatus to acquire radial calibration data sets throughout time. Example systems and methods also control the pMRI apparatus to acquire an under-sampled radial data set from the object to be imaged. Example systems and methods then control the pMRI apparatus to reconstruct an image of the object to be imaged from the under-sampled radial data set. The reconstruction depends, at least in part, on a through-time radial GRAPPA calibration where a value for a point missing from k-space in the under-sampled radial data set is computed using a GRAPPA weight set calibrated and applied for the missing point. The GRAPPA weight set is computed from data in the radial calibration data sets. | 04-21-2011 |
20110096092 | NON-CARTESIAN CAIPIRINHA - Example systems, methods, and apparatus concern non-Cartesian CAIPIRINHA (Controlled Aliasing In Parallel Imaging Results IN Higher Acceleration). One example parallel magnetic resonance imaging (pMRI) apparatus includes a radio frequency (RF) manipulation logic configured to control the pMRI apparatus to perform a non-Cartesian CAIPIRINHA acquisition process in which under-sampled data is acquired using a non-Cartesian (e.g., radial) pattern. The apparatus also includes a reconstruction logic configured to reconstruct the under-sampled data as a function of phase shift applied by the non-Cartesian CAIPIRINHA acquisition process and coil sensitivities acquired during the non-Cartesian CAIPIRINHA acquisition process. | 04-28-2011 |
20110175610 | NON-CARTESIAN UNDER-SAMPLED MULTI-ECHO MRI - Example apparatuses and methods control a magnetic resonance imaging (MRI) apparatus to perform a non-Cartesian, under-sampled, multi-echo MRI process. One example process includes controlling the MRI apparatus to excite an object to be imaged using a multi-echo Gradient Recalled Echo (GRE) pulse sequence. The example process also includes controlling the MRI apparatus to acquire a data set from the object to be imaged as a function of performing a non-Cartesian, under-sampling acquisition. The data set includes data acquired at two or more echo times (TE) per repetition (TR) and an element in the data set is sampled two or more times as a function of a non-Cartesian trajectory that crosses itself at least once. The process also includes controlling the MRI apparatus to reconstruct an image of the object to be imaged from the data set. The image may map brain activity. | 07-21-2011 |
20110241681 | HALL EFFECT CURRENT SENSOR - Example systems, apparatus, circuits, and so on described herein concern a Hall effect current sensor that includes a planar portion of a conductor that is oriented perpendicular to a base magnetic field in which it is located. In the presence of the magnetic field, a differential voltage is produced across the planar portion that is proportional to a strength of the magnetic field and the amount of current flowing through the conductor. | 10-06-2011 |
20110241682 | ON-COIL CURRENT MODE CLASS D RF POWER AMPLIFIER IN HIGH FIELD PARALLEL TRANSMISSION MRI - Example systems, apparatus, circuits, and so on described herein concern parallel transmission in high field MRI. One example apparatus includes a balun network that produces out-of-phase signals that are amplified to drive current-mode class-D (CMCD) field effect transistors (FETs) that are connected by a coil that includes an LC (inductance-capacitance) leg. The LC leg is to selectively alter the output analog RF signal and the analog RF signal is used in high field parallel magnetic resonance imaging (MRI) transmission. | 10-06-2011 |
20110241685 | SWITCHED MODE PRE-AMPLIFICATION AND AM FEEDBACK FOR ON-COIL SWITCHED MODE AMPLIFIERS IN PARALLEL TRANSMISSION MRI - Example systems, apparatus, circuits, and so on described herein concern parallel transmission in MRI with on-coil current-mode (CMCD) amplifiers. One example apparatus includes switched voltage-mode class D (VMCD) pre-amplifiers. Another example apparatus includes amplitude modulation of the output of the CMCD amplifiers using feedback control based, at least in part, on a comparison of an envelope of transmit coil current to an envelope of an input RF pulse. | 10-06-2011 |
20110279118 | CONTROLLING MULTI-CHANNEL TRANSMITTER EFFECTS ON SPECIFIC ABSORPTION RATE - Systems, methods, and other embodiments associated with controlling the specific absorption rate (SAR) in a patient associated with a conductor are described. The conductor may be, for example, a wire associated with a pacemaker, a wire associated with a neurostimulator, an orthopaedic device, and so on. One example method includes calibrating a multi-channel transmitter associated with a magnetic resonance imaging (MRI) apparatus imaging the patient. The example method also includes controlling the MRI apparatus to transmit radio frequency (RF) energy to image the patient in a manner where the RF energy will only influence the SAR near the conductor in the patient less than a desired threshold amount. | 11-17-2011 |
20110311158 | MOTION ARTIFACT REMOVAL - Systems, methods, and other embodiments associated with removing motion artifacts from MR images are described. One example method includes controlling an MRI apparatus to acquire a fully sampled, centric-ordered, non-interleaved, data set from an object to be imaged and controlling a Generalized Auto-Calibrating Partially Parallel Acquisition (GRAPPA) logic to produce a GRAPPA duplicate of a single partition through the data set. The method also includes computing, from the GRAPPA duplicate, a GRAPPA navigator for a phase encoding (PE) line in the single partition and computing an error between the PE line in the single partition and a corresponding PE line in the GRAPPA duplicate using the GRAPPA navigator. The method also includes selectively replacing data in the PE line in the single partition with replacement data upon determining that the error exceeds a threshold. The method may include reconstructing an MR image based, at least in part, on the single partition. | 12-22-2011 |
20120001630 | DARK BLOOD BALANCED STEADY STATE FREE PRECESSION IMAGING - Systems, methods, and other embodiments associated with controlling a magnetic resonance imaging (MRI) apparatus to perform a balanced steady state free precession (bSSFP) technique that includes magnetization preparation with differentiated velocity encoding and spoiling residual transverse magnetization are described. The example systems, methods, and other embodiments are also associated with acquiring a dark blood image in response to the bSSFP technique. A dark blood image is one in which NMR signal acquired from an object subjected to the bSSFP technique and magnetization preparation includes NMR signal from flowing spins and NMR signal from non-flowing spins in a desired ratio. | 01-05-2012 |
20120197107 | GLUCOSE ANALYZING BLOOD EXAMINER (GABE) - In one embodiment, a nuclear magnetic resonance (NMR) apparatus is described. The example NMR apparatus includes a first field generator configured to apply a first magnetic field to a sample (e.g., blood, interstitial fluid). A pulse generator is configured to provide a radio frequency (RF) pulse sequence. The pulse sequence may include a first RF pulse and a second RF pulse. The frequency of the RF pulses is chosen to produce an NMR signal associated with a specific chemical species (e.g., glucose) in the sample. A phase logic is configured to measure the decay of the NMR signal by measuring the phase differences that have accumulated between the spins of the nuclei of the chemical species in the sample. A calculation logic is configured to measure the amount of the chemical species in the sample. | 08-02-2012 |