Patent application number | Description | Published |
20100141252 | METHOD TO DETERMINE A PREDETERMINED SIGNAL AMPLITUDE IN MR MEASUREMENTS - In a method and apparatus to determine a predetermined signal amplitude of an examination subject in an MR measurement in which multiple RF pulses are radiated into the examination subject in a pulse sequence in a pulse series with a repetition time TR that is smaller than the T | 06-10-2010 |
20100145181 | VESSEL-DEPENDENT FLIP ANGLE MODULATION IN TOF MR ANGIOGRAPHY - In a method to excite a magnetization in the generation of MR angiography images with the TOF technique, a slice plane is determined in which the magnetization for the generation of the MR angiography images should be excited, a position of a vessel in the slice plane is determined, and the magnetization is excited in the slice plane such that the magnetization in the vessel has a flip angle gradient in the direction of the vessel. | 06-10-2010 |
20100253344 | MAGNETIC RESONANCE METHOD AND APPARATUS TO DETERMINE K-SPACE POSITIONS FOR MODELING RADIO-FREQUENCY PULSES - In a method magnetic resonance apparatus for the determination of k-space positions for modeling of RF pulses for magnetic resonance excitations, the following steps are implemented:
| 10-07-2010 |
20110172515 | DYNAMIC CORRECTION OF HIGH FREQUENCY ADJUSTMENT DURING PARALLEL TRANSMISSION - The present embodiments relate to a system and a method for operating an imaging system, where a plurality of subvolumes of an examination volume of an examination object to be examined with the system is examined. The examination volume is assembled from the plurality of subvolumes, where to examine the subvolumes, at least one HF pulse is transmitted in each case. The at least one HF pulse is optimized for the subvolume that is to be examined therewith respect to specifications and basic conditions applicable for the subvolume. | 07-14-2011 |
20110243420 | CORRECTION OF CHANGING LOCAL TRANSMIT PHASES DURING PARALLEL TRANSMISSION - The present embodiments relate to a device and a method for data postprocessing of K-space data acquired using a magnetic resonance tomography device. Each part of a K-space matrix is generated with one recording using a magnetic resonance tomography device in a plurality of recordings with the aid of a plurality of transmitting transmit channels of the magnetic resonance tomography device using excitation signals of one amplitude and phase. A field generated in total by the plurality of transmitting transmit channels is determined through addition of the spatial distribution of field distribution datasets representing a field generated by at least one transmit channel of the plurality of channels. A spatially dependent phase correction of the data is performed for data acquired in one recording using phases resulting from the added field distribution datasets. | 10-06-2011 |
20120074939 | MAGNETIC RESONANCE METHOD AND SYSTEM TO GENERATE AN OPTIMIZED MR IMAGE OF AN EXAMINATION SUBJECT - A magnetic resonance method and system for generation of an optimized MR image of an examination subject operate as follows. A pulse sequence including a series of at least two RF pulses is radiated into the examination subject to generate at least one optimized signal, wherein the second and possibly every additional RF pulse is radiated before the effect of the first or a preceding RF pulse on the spin system in the examination subject has decayed. The radiated RF pulses are generated by parallel transmission coils. At least the signal resulting after the last radiated RF pulse of the pulse sequence is acquired. The pulse sequence is repeated with modified spatial coding until signals have been generated and acquired in a desired positional space. The optimized MR image per pulse sequence is calculated from at least one of the acquired signals. | 03-29-2012 |
20120268130 | METHOD AND DEVICE FOR DETERMINING A MAGNETIC RESONANCE SYSTEM ACTIVATION SEQUENCE - A method and control a sequence determination device for determining a magnetic resonance system-activation sequence are provided. The magnetic resonance system-activation sequence includes a multichannel pulse having a plurality of individual HF pulses to be emitted in a parallel manner by the magnetic resonance system by way of different independent high-frequency transmit channels. A multichannel pulse is calculated based on a predefined MR excitation quality using an HF pulse optimization method, and an HF pulse length is optimized with respect to an HF energy parameter. | 10-25-2012 |
20130009640 | MAGNETIC FIELD INSENSITIVE CEST IMAGING - In a method for accelerated CEST imaging in magnetic resonance tomography, RF pulses for the saturation of the protons of the substance to be shown are emitted by several transmission coils, and shape of these RF pulses is calculated using an optimization method so that a weighted sum is minimized, the sum exhibiting at least two of the following norms: the norm of the magnetization of free water protons in each point in space, the norm of the deviation of the magnetization of the bound protons from an inverted magnetization in each point in space and the norm of the magnetization of protons with an inverted shift relative to the predefined frequency shift in each point in space. The shape of the RF pulses for subsequent excitation of the free water protons also can be calculated for the optimization method. | 01-10-2013 |
20130015854 | METHOD AND PROCESSOR AND MAGNETIC RESONANCE APPARATUS FOR DESIGNING RF PULSES TO MITIGATE OFF-RESONANCE EFFECTSAANM Adalsteinsson; ElfarAACI BelmonttAAST MAAACO USAAGP Adalsteinsson; Elfar Belmontt MA USAANM Fautz; Hans-PeterAACI ForchheimAACO DEAAGP Fautz; Hans-Peter Forchheim DEAANM Setsompop; KawinAACI CharlestownAAST MAAACO USAAGP Setsompop; Kawin Charlestown MA USAANM Wald; LawrenceAACI CambridgeAAST MAAACO USAAGP Wald; Lawrence Cambridge MA US - In a magnetic resonance apparatus and operating method therefor, and in a processor that is programmed to design RF pulses for operating such a magnetic resonance apparatus, the RF pulses are designed to mitigate off-resonance effects caused by inhomogeneity of the basic (B0) magnetic field in the magnetic resonance apparatus. The RF pulses of a parallel transmit array are designed with different spatial phase distributions, that deviate from a constant phase from pulse-to-pulse, with the absolute value of the difference between respective spatial phase distributions of any two successively radiated RF pulses corresponding to the off-resonance that is caused by B0-inhomogeneity during the time between the radiation of the successive pulses. Additionally, or separately, currents supplied to the shim coils can be taken into account in the design of the RF pulses as an additional degree of freedom, with the shimming of the basic magnetic field produced by the shim currents deviating from shim currents designed to ideally produce a homogenous B0 field. | 01-17-2013 |
20130033263 | METHOD AND MAGNETIC RESONANCE SYSTEM FOR ACQUIRING MAGNETIC RESONANCE DATA IN A PREDETERMINED REGION OF AN EXAMINATION SUBJECT - In a method and a magnetic resonance system to acquire MR data in a predetermined region within an examination subject, a first three-dimensional volume segment is selectively excited with an RF excitation pulse, this first volume segment including the predetermined region and having a first thickness along a first thickness direction. A selective refocusing pulse is activated in order to selectively refocus a second volume segment. The second volume segment likewise includes the predetermined region and has a second thickness along a second thickness direction orthogonal to the first thickness direction. | 02-07-2013 |
20130038327 | METHOD TO ACQUIRE A MAGNETIC RESONANCE IMAGE DATA SET OF A TARGET VOLUME - In a method to acquire a magnetic resonance image data set of a target volume with a magnetic resonance device, wherein the target volume is composed of a number of sub-volumes defined in a two-dimensional plane orthogonal to the readout direction, for each sub-volume, in order to acquire a partial data set of a sub-volume, a targeted excitation of the sub-volume and a data acquisition from that sub-volume to measure the partial data set take place by radiation of a first radio-frequency pulse acting in a first direction of the plane and radiation of a second radio-frequency pulse acting in a second direction that is orthogonal to the first direction. The partial data sets are combined into the magnetic resonance data set. | 02-14-2013 |
20130134973 | Method for Determining a Control Sequence with Parallel Transmission - A method for determining a set of control parameters of a control sequence for a magnetic resonance device is provided. The set of control parameters is chosen from a plurality of sets of basic parameters. The method includes determining a mean flip angle for each set of basic parameters in an imaging region where an object exists using the set of basic parameters with a first measuring method. For each set of basic parameters, a signal strength of a magnetic resonance signal generated in the case of a reference flip angle of a second measuring method distinguished by a signal maximum or a signal minimum is determined, and the set of basic parameters having a signal strength that is extremal in accordance with the choice of reference flip angle is chosen as the set of control parameters. | 05-30-2013 |
20130214782 | FLOW-SENSITIVE, FREQUENCY-INDEPENDENT EXCITATION OF MAGNETIC RESONANCE SIGNALS - A transmit coil system of a magnetic resonance system is exposed to high-frequency transmit pulses so that atomic nuclei of a predetermined type of atomic nucleus of an examination object introduced into an examination volume are excited by the high-frequency transmit pulses to emit magnetic resonance signals. A gradient magnetic system is exposed to gradient currents during the exposure of the examination volume to the high-frequency transmit pulses so that gradient magnetic fields are superimposed on a basic magnetic field generated by a basic magnet in the examination volume. The gradient currents and the high-frequency transmit pulses are matched to each other such that the atomic nuclei are exclusively those with a velocity lying within or outside a predetermined velocity range. The excitation is independent of variations in the Larmor frequency of the relevant type of atomic nucleus caused by inhomogeneities of the basic magnetic field and/or by chemical displacement. | 08-22-2013 |
20130221962 | METHOD FOR DETERMINING AN ACTIVATION SEQUENCE FOR A MAGNETIC RESONANCE DEVICE - A method for determining an activation sequence for a magnetic resonance device is provided. The activation sequence includes single pulses to be emitted simultaneously for a plurality of individually activatable high-frequency transmission channels. The method includes determining an amplitude and a phase of a plurality of square-wave subpulses, of which the single pulse is composed, by a pulse optimization method for a predefined target magnetization for each of the single pulses. The method also includes determining optimized, layer-selective subpulses for each square-wave subpulse of the plurality of square-wave subpulses while retaining phase and integral of the square-wave subpulse with regard to a bandwidth of the plurality of square-wave subpulses and/or the quality of a profile of a layer to be excited. | 08-29-2013 |
20130229176 | Method for Determining a Set of B1 Field Maps - A method for determining a set of B1 field maps for different transmit channels includes determining a first partial B1 field map having absolute B1 amplitudes for each transmit channel. A gradient echo technique operating with a single gradient echo image is used to determine a relative partial B1 field map having relative B1 amplitudes for each transmit channel. A spatial weighting function for mapping the relative B1 amplitudes onto absolute B1 amplitudes is determined taking into account the first partial B1 field maps and the relative partial B1 field maps of all the transmit channels. The spatial weighting function is used to determine second partial B1 field maps from the relative partial B1 field maps. The B1 field map for each transmit channel is determined from the first and the second partial B1 field map for the respective transmit channel taking into account the subregions and/or the error values. | 09-05-2013 |
20130257427 | Determining a Magnetic Resonance System Control Sequence - A method and a control sequence determination device are provided for determining a magnetic resonance control sequence that includes a multichannel pulse train with a number of individual RF pulse trains sent out in parallel by a magnetic resonance system over different independent radio-frequency transmit channels. The multichannel pulse train is calculated based on a predetermined target function with a predetermined target magnetization in an RF pulse optimization method. The RF pulse optimization method takes account of the magnetization in the form of a non-linear equation and of a local radio-frequency load and in a plurality of volume elements in the form of quadratic equation systems. | 10-03-2013 |
20130265049 | Controlling Magnetic Resonance Systems - A method for controlling a magnetic resonance system outputs a pulse sequence including a first slice-selective excitation pulse that excites a first slice with a first magnetization. The pulse sequence includes a second slice-selective excitation pulse that excites a second slice with the first magnetization and a third slice-selective excitation pulse that excites the first slice with a second magnetization that cancels the first magnetization. The pulse sequence also includes and a fourth slice-selective excitation pulse that excites the second slice with a magnetization that cancels the first magnetization. The first slice and the second slice intersect. | 10-10-2013 |
20140077802 | METHOD AND CONTROL DEVICE TO CONTROL A MAGNETIC RESONANCE SYSTEM - A method and control device operate a magnetic resonance system in order to execute a first pulse sequence that includes an excitation phase and an acquisition phase. In the excitation phase, a first gradient is applied in a gradient direction to generate a spatially dependent basic magnetic field. A selective radio-frequency excitation pulse is executed, wherein the selective radio-frequency excitation pulse excites a first material and does not excite a second material in a first partial region of an examination volume, and wherein the selective radio-frequency excitation pulse does not excite the first material and excites the second material in a second partial region of the examination volume. In the acquisition phase, non-selective refocusing pulses are executed in order to acquire raw data of the first and second partial region of the examination volume, which acquisition is spatially coded along the gradient direction. | 03-20-2014 |
20140132262 | Method and Apparatus for SAR Reduction Using B0 Specific RF Excitation - A method for generation of a radio-frequency (RF) pulse for excitation of nuclear spins in a predetermined layer of a specimen for magnetic resonance imaging and a magnetic resonance imaging device for performing the method are provided. The method includes determining a variation of a magnetic field in a measuring volume, and defining a spectral frequency distribution of the RF pulse. The RF pulse with the spectral frequency distribution is configured to excite nuclear spins in the specimen. The nuclear spins are polarized by the magnetic field at a predetermined flip angle in the measuring volume under a boundary condition of a substantially minimum energy content. The method also includes generating the RF pulse with the defined spectral frequency distribution. | 05-15-2014 |
20140159722 | METHOD TO GENERATE AN RF EXCITATION PULSE TO EXCITE AN ARBITRARILY SHAPED VOLUME, METHOD FOR TARGETED EXCITATION OF SPINS WITHIN A VESSEL, AND METHOD TO CREATE MR ANGIOGRAPHY IMAGES, AND MAGNETIC RESONANCE SYSTEM - In order to generate an RF excitation pulse together with a gradient curve to excite nuclear spins an arbitrarily shaped volume with a magnetic resonance system, a volume segment is prepared in which the volume is situated, such that only spins within the volume yield an MR signal portion in the subsequent detection of an MR signal. An MR signal is detected from the volume segment along a trajectory of k-space. At least one gradient for scanning k-space along the trajectory is switched during the detection. The RF excitation pulse is generated corresponding to the MR signal detected in a temporally inverted manner, and the gradient curve is generated corresponding to the temporally inverted curve of the at least one gradient to scan k-space. | 06-12-2014 |
20140218027 | METHOD FOR MAGNETIC RESONANCE IMAGING, AND MAGNETIC RESONANCE SYSTEM - In magnetic resonance imaging using a measurement sequence of the “free precession of transverse magnetization in the steady state”-type i.e., an SSFP measurement sequence, during the SSFP measurement sequence, the implementation of a preparation sequence takes place to reduce a signal contribution of the transverse magnetization in an outer region surrounding a measurement region in the MR imaging. The implementation of the preparation sequence includes the radiation of a multidimensional, spatially selective RF pulse that acts in a spatially selective manner on the transverse magnetization in the outer region. Saturation of the transverse magnetization and/or dephasing of the transverse magnetization in the outer region can be achieved by the multidimensional, spatially selective RF pulse. | 08-07-2014 |
20140292331 | METHOD FOR THE ADJUSTMENT OF AT LEAST ONE MAGNETIC RESONANCE IMAGE DATA SET OF A MOVABLE EXAMINATION OBJECT AND CORRESPONDINGLY DESIGNED MAGNETIC RESONANCE DEVICE - A method for the adjustment of at least one magnetic resonance image data set of a movable examination object and correspondingly designed magnetic resonance device is provided. Moreover, a method, a computer program product and a computer-readable storage medium for the adjustment by a magnetic resonance device of at least one magnetic resonance image data set of a movable examination object is provided. After capturing two different types of position data for determination of the position of the examination object using navigator measurements and with the help of external markers, recording parameters and/or reconstruction parameters for recording and/or reconstruction of the at least one magnetic resonance image data set are adjusted as a function of the first and/or the second position data. | 10-02-2014 |
20140292332 | DEVICE, METHOD AND SYSTEM FOR CONTROLLING IMAGING METHODS AND SYSTEMS - In a computer-implemented method, device and system for controlling an imaging system, a specific absorption rate is calculated with a computation unit and an RF transmission signal of the imaging system is controlled with a control device. The process of controlling of the RF transmission signal includes disconnecting the RF transmission signal when a remaining period during which the RF transmission signal is harmless for the patient has been reduced to zero. | 10-02-2014 |
20140300355 | Method and Local Coil System for Producing a Magnetic Resonance Radio Frequency Field - A magnetic resonance RF field is produced in a magnetic resonance imaging system that includes a main magnetic field apparatus and an object-bearing table movable relative to the main magnetic field apparatus and on which a local coil system is arranged. The local coil system includes a plurality of transmission elements. A current location of the object-bearing table relative to the main magnetic field apparatus is established. The transmission elements are automatically connected based on the current location of the object-bearing table. | 10-09-2014 |
20140306708 | Magnetic Resonance Apparatus with Group-by-Group Actuation of Transmission Antennas - A magnetic resonance apparatus including transmission antennas that may be actuated in parallel by a control device of the magnetic resonance apparatus may be operated in a group mode. In the group mode, the transmission antennas are grouped into groups of transmission antennas. The actuation signals of transmission antennas within the respective group are in a respectively predefined relationship relative to one another. A respective group actuation signal for each of the groups of transmission antennas is prescribed for the control device by an operator. The control device carries out checks as to whether a group exposure value established based on the group actuation signals lies below a maximum admissible group exposure limit. If this is the case, the control device establishes the actuation signals for the individual transmission antennas based on the group actuation signals. If this is not the case, the control device carries out another measure. | 10-16-2014 |
20140307764 | Operation of a Transmission Device of a Magnetic Resonance Device - A method for operating a transmission device of a magnetic resonance device is provided. In order to actuate coil elements of a radiofrequency coil with different phases, phase differences in a reference plane are taken into consideration. In a first calibration measurement to be performed once for each transmission path, a first phase of a transmitted radiofrequency signal is measured by an internal measuring device installed permanently in the transmission device spaced apart from the reference plane. A second phase of the transmitted radiofrequency signal is measured by a second, external measuring device to be connected to the reference plane for the first calibration measurement. At least one phase of the first phase and the second phase is taken into consideration in the phase-accurate actuating of the coil elements and/or for correcting further measurements with the internal measuring device. | 10-16-2014 |
20150015257 | METHOD AND MAGNETIC RESONANCE APPARATUS TO DETERMINE A B0 FIELD MAP - In a method and magnetic resonance apparatus to determine a B0 field map describing the local deviation from a nominal Larmor frequency of the magnetic resonance apparatus, magnetic resonance data are acquired at at least two different dephasing times after an excitation, in measurements implemented at two different echo times whose difference forms a dephasing time, and a phase change used to determine the B0 field map is determined from a difference of phases measured at different echo times. The phase changes of different dephasing times are evaluated to at least partially reduce an ambiguity due to Nyquist phase wrapping. The measurements for different dephasing times are implemented at least in part with excitations that generate different excitation fields. | 01-15-2015 |
20150015258 | METHOD AND MAGNETIC RESONANCE APPARATUS TO DETERMINE A B1 PHASE MAP - In a method to determine a B1 phase map for at least two excitation modes of a radio-frequency coil arrangement of a magnetic resonance apparatus, the radio-frequency coil arrangement having multiple independently controllable transmission channels, and the B1 phase map describing, with spatial resolution, the phase of radio-frequency field this is generated in a respective excitation mode relative to a common reference phase map, first magnetic resonance data describing the phase change of a basic magnetic field of the magnetic resonance apparatus between a first echo time and a second echo time are acquired, and are evaluated to determine a spatially resolved Larmor frequency value that describes the deviation from a nominal Larmor frequency of the magnetic resonance apparatus. To correct raw phase maps derived from second magnetic resonance data acquired using a respective one of the excitation modes, a correction map, determined relative to the reference phase map, is calculated and subtracted from the raw phase map under consideration of the Larmor frequency value and the echo times in the acquisition of the second magnetic resonance data. | 01-15-2015 |
20150019172 | MAGNETIC RESONANCE IMAGING METHOD AND APPARATUS - A magnetic resonance (MR) tomography aparatus has an array composed of a number n of single coils E | 01-15-2015 |
20150022203 | Automatic HF Shim Configuration for Coils - In order to configure a transmission coil of a magnetic resonance imaging (MRI) system without taking a specific measurement object into account, the transmission coil is automatically detected and identified when the transmission coil is connected to the MRI system. A phase setting of a pulse to be transmitted by the detected transmission coil is identified based on at least the identified type of the transmission coil. The transmission coil is excited with the pulse having the identified phase and amplitude. | 01-22-2015 |
20150077108 | Measurement of Radio Frequency Excitation Pulses - The embodiments relate to methods for measurement of RF excitation pulses by a magnetic resonance device including the following acts: (1) sending of an RF excitation pulse by a radio-frequency system of the magnetic resonance device, (2) triggering of a receive event for capturing the RF excitation pulse by the control device of the magnetic resonance device, and (3) capturing of the sent RF excitation pulse in the form of excitation data by the radio frequency system. In certain embodiments, the excitation data is used for checking process execution sequences. | 03-19-2015 |
20150077115 | METHOD AND COMPUTER TO DETERMINE A B0 FIELD MAP WITH A MAGNETIC RESONANCE APPARATUS - In a method to determine a B0 field map describing the local deviation of a nominal Larmor frequency of a magnetic resonance apparatus, wherein magnetic resonance data are acquired in measurements implemented at two different echo times whose difference forms a dephasing time after an excitation at at least two different dephasing times, and a phase change to be used to determine the B0 field map is determined from a difference of phases measured at different echo times, the phase changes of different dephasing times are evaluated to at least partially reduce an ambiguity due to a Nyquist phase wrapping, by using dephasing times that result as a quotient or, given the use of only two dephasing times, as a product, of a base time and a respective prime number from a group including at least two different prime numbers that are greater than one, and wherein the group is selected depending on a desired dynamic range of the B0 field map and/or a maximum tolerated measurement error for the measurements. | 03-19-2015 |