Siemens Healthcare Gmbh

Siemens Healthineers Ag

Siemens Aktiengesellschaft

Michael Köhler

Mario Zeller

Dominik Paul

Markus Vester

David Grodzki

Thorsten Feiweier

Jürgen Nistler

Alto Stemmer

Dieter Ritter

Flavio Carinci

Daniel Niederlöhner

Johann Sukkau

Andreas Krug

Michael Wullenweber

Gudrun Ruyters

George William Ferguson

Uvo Hölscher

Wilfried Landschütz

Petra Bildhauer

Constantin Von Deuster

In a method for measuring a gradient field in a magnetic resonance tomography (MRT) system, a first slice is excited by a first radio frequency (RF) pulse being emitted and by a first slice selection gradient being switched at least partly at the same time as the first RF pulse. A second slice is excited by a second RF pulse being emitted and by a second slice selection gradient being switched at least partly at the same time as the second RF pulse. The second slice intersects with the first slice in an intersection region. After the excitation of the second slice, a readout gradient is switched, and an MR signal emitted from the intersection region is acquired. Depending on the MR signal, a disruption variable is computed, which determines a deviation of a temporal course of an amplitude of the readout gradient from a predetermined required course.

Measurement of a gradient field in an MRT system

A method for calibrating gradient amplifiers of a magnetic resonance apparatus is provided. The magnetic resonance apparatus includes one or more gradient coils that include at least two coil segments configured to generate a gradient magnetic field with a gradient in a spatial direction, and a gradient amplifier for each of the at least two coil segments. The gradient amplifier is configured to supply the respective coil segment with electric current. A plurality of magnetic field distributions are measured, each being generated via at least one coil segment of the at least two coil segments. For measuring each magnetic field distribution of the plurality of magnetic field distributions, the at least one coil segment that generates the respective magnetic field distribution is supplied with a predetermined electric current via the respective gradient amplifier. The gradient amplifiers are calibrated via a comparison of the plurality of measured magnetic field distributions.

Method for calibrating gradient amplifiers of a magnetic resonance apparatus, magnetic resonance apparatus, and computer program product

Eddy current induced magnetic fields (MF) are compensated in a magnetic resonance imaging system. An MR-sequence (M) includes a number of gradients. A dataset includes values of an amplitude and a time constant of eddy current fields of a number of gradients on at least one gradient axis. A number of points in time within the time period of the MR-sequence are defined. A number of constant currents are calculated for a number of coils of the magnetic resonance imaging system based on the dataset. The number of constant currents is designed to compensate at least at the one defined point in time (PT, PT). The calculated number of constant currents are applied on the related coils prior or during the application of the MR-sequence or a section of the MR-sequence.

Method and control unit for compensation of eddy current induced magnetic fields in magnetic resonance imaging

A method for operating a magnetic resonance facility in which a measurement gradient pulse is used to record magnetic resonance signals for sampling k-space along a trajectory section. The recorded magnetic resonance signals are assigned to k-space points using a shape function describing the time profile of the measurement gradient pulse. To correct deviations of the real time profile of the measurement gradient pulse from an assumed target profile, a first correction measurement is performed to ascertain first magnetic resonance signals of the trajectory section. A second correction measurement is then performed using a reference sampling pattern or a reference gradient pulse with fewer deviations from an assigned reference target profile. If a deviation criterion is met, a correction function for the shape function is ascertained by aligning the first and second magnetic resonance signals to one another, providing correction information to be used in an imaging measurement.

Magnetic resonance facility operation

In a method, an imaging sequence is irradiated into an examination region in which an examination object is located. The imaging sequence includes an acquisition section. The acquisition section includes acquiring a plurality of echo signals, each of which samples a k-space region of a k-space. The plurality of echo signals comprises a plurality of first echo signals and a plurality of second echo signals. The plurality of first echo signals and the plurality of second echo signals are generated from different magnetization configurations. The k-space regions sampled by the plurality of first echo signals sample the k-space in a different order to the k-space regions sampled by the plurality of second echo signals.

Echo-specific k-space sampling with multi-echo sequences

The disclosure relates to a magnetic resonance tomography scanner and to a method for operating the magnetic resonance tomography scanner. The method includes determining a B0 field map. The method further includes determining an excitation of the nuclear spins to be achieved and a spectrally selective excitation pulse for transmission by a transmitter by way of an antenna as a function of the B0 field map. In the method, the excitation pulse is configured here to generate the excitation of the nuclear spins to be achieved in the patient. The excitation pulse is then output by way of the antenna.

Magnetic resonance tomography scanner and method for operating with dynamic B0 compensation

A computer-implemented method for provision of a result dataset having position information of a local radio-frequency coil, including: providing input data having at least magnetic resonance data, which is acquired by means of the local radio-frequency coil; determining a result dataset by applying a trained function to the input data, wherein the result dataset comprises position information for determining the position of the local radio-frequency coil; and providing the result dataset.

Provision of position information of a local RF coil

In a method for providing setting parameter sets for at least one measuring protocol described by protocol parameters for acquiring magnetic resonance data with a magnetic resonance facility, setting parameter set is determined for each of at least two temperature status categories of the magnetic resonance facility using a temperature model describing a development of a temperature status of at least one component of the magnetic resonance facility. The method also includes preventing overheating of the at least one component due to the measurement with the measuring protocol being repeated a maximum number of times for a specified number of repetitions.

Method for providing setting parameter sets for a magnetic resonance facility, method for operating a magnetic resonance facility, provision facility, magnetic resonance facility and computer program

The disclosure relates to a method for generating a Bmap for a magnetic resonance examination of an examination subject, a magnetic resonance device, and a computer program product for executing the method. The method provides for the application of at least two preparatory RF pulses during a preparatory stage and at least one readout RF pulse during an acquisition stage. At least one stimulated echo signal is acquired after the readout RF pulse. A Bmap that shows the actual spatial distribution of the magnetic field strength of the main magnetic field is derived from the at least one acquired FID echo signal and the at least one acquired stimulated echo signal.

Time-saving generation of a Bmap based on a dual echo sequence with stimulated echoes

A control device establishes a change in a main magnetic field expected for a respective time instant and based on the established expected change in the main magnetic field, correctively adjusts the main magnetic field and/or a nominal receive frequency of the RF receive coil and/or a transmit frequency for subsequent RF transmit pulses and/or takes the expected change in the main magnetic field into account in the evaluation of the received MR signals. At least for some of the RF transmit pulses, the control device acquires, via a sensor device, a portion of the respective radiofrequency wave supplied to the RF transmit coil. The controller extracts therefrom an oscillation corresponding to a respiratory motion of the patient and based on the variation with time of the extracted oscillation, establishes the change in the main magnetic field expected for the respective time instant.

Establishing changes in a B0 field from reflected waves

The disclosure relates to a method for correcting image data acquired by a magnetic resonance device, a magnetic resonance device, and a computer program product. According to the method, first navigator data, image data, and second navigator data are acquired. Moreover, temperature values of the magnetic resonance device are determined. The image data is corrected based on the first navigator data, the second navigator data, and the temperature values.

Temperature-dependent correction of magnetic resonance image data

Systems and methods for measuring eddy current fields occurring as a result of gradient pulses in a magnetic resonance sequence at a point in time during the magnetic resonance sequence in relation to at least one direction of pulse effect. At least the parts of the magnetic resonance sequence comprising the gradient pulses relating to the at least one direction of pulse effect are performed as a preparation sequence up until the point in time followed directly by a measurement sequence in which first measurement data is recorded. The preparation sequence is played out again with the same, directly consecutive measurement sequence without the gradient pulses relating to the at least one direction of pulse effect or with gradient pulses having an inverted sign relating to the at least one direction of pulse effect. Second measurement data is recorded. Using a joint evaluation of the first and second measurement data at least one variable characterizing the eddy current field generated by the eddy currents of the gradient pulses in the at least one direction of pulse effect is determined.

Method for measuring eddy current fields in a magnetic resonance device, magnetic resonance device, computer program and electronically readable data carrier

A phase difference caused by eddy currents is determined for an MR system. First MR data is acquired with a first sequence by irradiating at least one RF pulse having an RF excitation pulse, importing a first test gradient during or after the RF excitation pulse, applying a read-out gradient, and acquiring the first MR data while the read-out gradient is switched, so the first MR data is acquired for at least one K-space line. Second MR data is acquired with a second sequence by importing a second test gradient during or after the RF excitation pulse, and applying the read-out gradient. The second MR data is acquired while the read-out gradient is switched, so the second MR data is acquired for the at least one K-space line. The phase difference per voxel is determined using the first MR data and the second MR data.

Determining a phase difference caused by eddy currents for a magnetic resonance system

In a method, by a magnetic resonance device, a transmit Bfield map is determined for a region, a plurality of MR images of at least one part of the region are acquired using transmitter settings differing from each other, and signal intensities of individual pixels measured by the MR images are interpolated by the transmit Bfield map. A correction of the signal intensities may also be effected by carrying out a receive Bcorrection by a spatial mirroring of the transmit Bfield map on a symmetry plane of a measured object. A magnetic resonance device is used to carry out the method. The method may be applied, for example, in medical diagnostics.

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Nuremberg, Germany

Michael Köhler