| Patent application number | Description | Published |
|---|
| 20080227416 | ARRANGEMENT FOR CONTROLLING INDIVIDUAL ANTENNAS OF AN ANTENNA ARRANGEMENT - An arrangement for controlling individual antennas of an antenna arrangement in a magnetic resonance apparatus has a device for signal division. This device is designed such that each transmission signal present at an input of the device for signal division is divided among all outputs of the device for signal division. Each output of the device for signal division is connected with a respective individual antenna. A number of transmission branches are provided for the inputs of the device for signal division. Each transmission branch has components that form a transmission signal that is modulated specific to the transmission branch and is amplified. Each transmission branch is connected with a respective associated input of the device for signal division, such that the transmission signal therefrom arrives at the associated input. | 09-18-2008 |
| 20080231274 | METHOD TO CONTROL A MAGNETIC RESONANCE SYSTEM - In a method for controlling a magnetic resonance system having a radio-frequency antenna structure and a number of individually controllable transmission channels, respective parallel radio-frequency signals are emitted via the transmission channels for generation of a desired radio-frequency field distribution in at least one specific volume region within an examination volume of the magnetic resonance system. A digital signal is generated for each of the transmission channels and is modulated on a carrier frequency. The radio-frequency signal so generated is transmitted via a radio-frequency signal path to the radio-frequency antenna structure and is amplified therein in a radio-frequency power amplifier. The digital signal is manipulated in a characteristic curve correction device on the basis of a correction characteristic curve predetermined for the respective radio-frequency signal path such that a distortion of the radio-frequency signal caused in the appertaining radio-frequency signal path is at least partially compensated. Respective individual correction characteristic curves for a specific measurement are predetermined for the various transmission channels dependent on a field distribution parameter that defines the desired radio-frequency field distribution. A magnetic resonance system implements such a method. | 09-25-2008 |
| 20080284432 | METHOD FOR CONTROLLING A MAGNETIC RESONANCE SYSTEM - In a method for controlling a magnetic resonance system with a number of individually controllable transmission channels, a limited number of antenna control parameter sets are available that are associated with respective different examination situation classes that are defined with regard to specific examination situation parameters. The antenna control parameter sets include, for each of the transmission channels, a channel value or a channel value combination with which a relative amplitude and a relative phase of a radio-frequency signal emitted via the appertaining transmission channel are defined. Respective current examination situation parameter values to be associated with the examination situation parameters for the magnetic resonance measurement to be implemented are then detected and one of the examination situation classes is selected based on this. The magnetic resonance measurement is then implemented with the antenna control parameter set associated with the selected examination situation class. | 11-20-2008 |
| 20090079428 | MAGNETIC RESONANCE RF TRANSMISSION SYSTEM AND MR SYSTEM AND METHOD USING SAME - A radio-frequency transmission system for a magnetic resonance system has a radio-frequency amplifier and a signal splitter with two inputs and two outputs. The signal splitter is fashioned so that the power of a radio-frequency signal provided at one of the two inputs is divided between the two outputs. A first input the two inputs of the signal splitter is thereby coupled with the output of the radio-frequency amplifier, and the two outputs of the signal splitter respectively serve for connection to different inputs of a transmission antenna of the magnetic resonance system in order to feed the output signals present at the two outputs of the signal splitter into the transmission antenna. The second input of the signal splitter is terminated with a terminating resistor arrangement with a variable reflection factor. | 03-26-2009 |
| 20090189609 | APPARATUS FOR CONTROLLING AN ANTENNA ARRANGEMENT - A cylindrical antenna arrangement in a magnetic resonance apparatus has two feed points to feed in two partial signals, the two feed points being arranged on a cross-section of the antenna arrangement. The cross-section has a center point. A first angle is formed by the connection of a first feed point with the center point relative to a horizontal axis of the cross-section while a second angle is formed by the connection of a second feed point with the center point relative to the horizontal axis of the cross-section. An apparatus for controlling such an antenna arrangement has a device for signal splitting with two outputs and an input. A radio-frequency magnetic resonance signal is connected at the input. This signal is divided by the device for signal splitting into two partial signals of equal amplitude that are respectively supplied to an associated output. Each output of the device for signal splitting is connected with precisely one associated feed point of the antenna arrangement. An ellipse position in space is set for an elliptical polarization via the selection of the two angles. A device for phase adjustment is interposed between precisely one output of the device for signal splitting and the associated feed point in order to set an elliptical semi-axis ratio via variation of the phase difference of the two partial signals. | 07-30-2009 |
| 20090192382 | MAGNETIC RESONANCE SYSTEM, ANTENNA SYSTEM, METHOD FOR DESIGNING A MAGNETIC RESONANCE SYSTEM AND METHOD TO GENERATE MAGNETIC RESONANCE EXPOSURES - A magnetic resonance system obtaining magnetic resonance exposures of an examination subject, has an examination tunnel, a whole-body antenna with two connection terminals. The whole-body antenna cylindrically extends around the examination tunnel along a longitudinal axis. The system has a radio-frequency supply device in order to respectively supply the whole-body antenna with radio-frequency signals for emission of a radio-frequency field in the examination tunnel. The radio-frequency supply device has a radio-frequency generator for generation of a radio-frequency signal, a signal splitter that divides a radio-frequency signal coming from the radio-frequency generator into two partial signals that are phase-shifted by 90° relative to one another. Two radio-frequency feed lines are connected with the two connection terminals of the whole-body antenna. Via these radio-frequency feed lines, the two partial signals are fed into the whole-body antenna. The whole-body antenna has an intrinsic transmission characteristic such that a radio-frequency field is emitted that is elliptically polarized in a defined manner in a plane lying perpendicular to the longitudinal axis (at least in the unloaded state of the examination tunnel). | 07-30-2009 |
| 20090322329 | MAGNETIC RESONANCE APPARATUS AND METHOD FOR DETERMINING A PULSE SEQUENCE TO FEED AN RF RADIATING COIL - In a magnetic resonance apparatus having an RF radiating coil and gradient coils, and in a method for operating such a magnetic resonance apparatus, a pulse sequence, composed of multiple time steps, is specified for operating the gradient coils to time-dependently select regions of a selected slice of a selected volume of a subject. A non-linear equation system is then solved to obtain feed parameters for individual channels of the transmit coil for each time step, with specification of a desired target magnetization, and dependent on the pulse sequence specified for the gradient coils. The non-linear equation system is based on discrete values for time and space variable and, in addition to equations resulting from the Bloch equation, which are non-linear in their feed parameters, includes at least one additional equation that describes boundary conditions for the examination of the subject. | 12-31-2009 |
| 20100167668 | METHOD AND DEVICE FOR MONITORING A RADIO-FREQUENCY TRANSMITTER DEVICE IN A MAGNETIC RESONANCE TOMOGRAPHY SYSTEM - In a method and device for monitoring a radio-frequency transmit device of a magnetic resonance tomography system, having a transmitter antenna system that has a number of transmit channels, during a magnetic resonance measurement of an examination subject, a reference scattering parameter matrix of the transmitter antenna system is determined in the unloaded state, and a subject-specific scattering parameter matrix of the transmitter antenna system is determined in a state loaded with the subject of examination. Moreover, transmitter amplitude vectors are determined in time-dependent fashion that represent the radio-frequency voltage amplitudes on the individual transmit channels. On the basis of the subject-specific scattering parameter matrix, the reference scattering parameter matrix, and the transmit amplitude vectors, radio-frequency power values absorbed at particular transmit times in the subject are determined. Based on a large number of the determined radio-frequency power values, a number of monitoring values are formed. The radio-frequency transmit device is limited in its functioning when a monitoring value reaches or exceeds a prespecified boundary monitoring value. | 07-01-2010 |
| 20100188086 | MAGNETIC RESONANCE ANTENNA - A magnetic resonance antenna has capacitive and inductive oscillating circuit antenna elements at least one radio-frequency switching element with which at least one of the oscillating circuit antenna elements that determine the resonant frequency of the magnetic resonance antenna, can be switched at radio frequency between a permeable state and an impermeable state to change the resonant frequency of the magnetic resonance antenna, so the antenna can be detuned simply, cost-effectively and efficiently. | 07-29-2010 |
| 20100225320 | RF STRIPLINE ANTENNA WITH IMPEDANCE ADAPTATION FOR MR IMAGING - The efficiency and the field structure of an antenna arrangement for a magnetic resonance tomography apparatus are improved by at least one impedance transformation circuit connected with the antenna. | 09-09-2010 |
| 20100308825 | METHOD AND DEVICE FOR SELECTING BODY MODEL POSITIONS FOR SAR MONITORING OF A MAGNETIC RESONANCE TRANSMIT ARRAY - In a method and a device for specific absorption rate monitoring in a magnetic resonance system wherein multiple transmit coils are independently charged with respective currents, a primary model point voxel and at least one auxiliary model point voxel are automatically selected from among multiple voxels that model a modeled examination subject. The primary model point voxel is that voxel in which an absolute maximum of a total field variable occurs that is produced by the respective electrical fields emitted by the transmit coils. The at least one auxiliary model point voxel is that voxel in which a relative maximum of the variable occurs. The primary model point voxel and the at least one auxiliary model point voxel are stored, and specific absorption rate monitoring of an actual examination subject in the magnetic resonance system is implemented during the acquisition of magnetic resonance data in respective voxels of the actual examination subject corresponding to the stored primary model point voxel and the stored at least one auxiliary model point voxel. | 12-09-2010 |
