Siemens Aktiengesellschaft

Siemens Healthcare Gmbh

Siemens Aktiengesell Schaft

Siemens Healthineers Ag

Gerhard Brinker

Matthias Gebhardt

Wolfgang Bielmeier

Markus Vester

David Grodzki

Dominik Paul

Swen Campagna

Gudrun Ruyters

Carsten Prinz

Bernd Erbe

Jürgen Nistler

Nikolaus Demharter

Juergen Nistler

Klaus Ludwig

Volker Schnetter

Franz Hebrank

Stephan Stoecker

Stephan Stöcker

Richard Koellner

Wolfgang Renz

Dirk Diehl

Helmut Lenz

Stephan Nufer

Jan Ole Blumhagen

Daniel Niederloehner

Georg Frese

Volker Weissenberger

Anja Jaeger

Jens Thoene

Patrick Sieber

Friedrich Arneth

Nicolas Groß-Weege

In a magnetic resonance apparatus and a method for operation thereof, at least one electrical operating value of at least one predetermined component of the apparatus is captured and, as a function of the at least one operating value, at least one coil operating value of a transmitting coil arrangement of the magnetic resonance apparatus is controlled for the purpose of limiting a B1 value.

Magnetic resonance apparatus and operating method therefor with monitoring and control of RF energy-relevant operating value

The disclosure relates to a method for monitoring an absorption rate when using a primary coil of a magnetic resonance device and a secondary coil inductively coupled to the primary coil and to a monitoring unit, a magnetic resonance device and a computer program product. According to the method a maximum admissible absorption rate is provided, using which a maximum admissible B1 field strength of the secondary coil is determined. Furthermore, an actual B1 field strength of the secondary coil is determined. The absorption rate is monitored using the actual B1 field strength of the secondary coil and the maximum admissible B1 field strength of the secondary coil.

Monitoring an absorption rate of inductively coupled coils

A method for monitoring a temporal change in a magnetic field in a magnetic resonance device, as well as an evaluation unit, a magnetic resonance device, and a computer program product for performing the method are provided. The method provides that a position-dependent magnetic field distribution that is produced by the plurality of gradient coils is provided with a plurality of monitoring points. In addition, time-dependent gradient values of the plurality of gradient coils are ascertained. Based on position-dependent magnetic field distribution and the time-dependent gradient values, the temporal change in the magnetic field is ascertained. The temporal change in the magnetic field is monitored by comparing the temporal change in the magnetic field with at least one limit value.

Monitoring of a temporal change in a magnetic field in a magnetic resonance device

In a method and apparatus for determining at least one patient-specific safety parameter for a medical imaging examination conducted on the patient by a medical imaging device, position data of the patient are acquired by a position data detector while the patient is on a patient-positioning device of the medical imaging apparatus. The acquired position data are evaluated in a processor in order to determine position information of the patient. The patient-specific safety parameter is determined using the position information of the patient.

Method and medical imaging apparatus for determining at least one patient-specific safety parameter for a medical imaging examination

A method for evaluating positioning of an examination object on a patient-positioning apparatus in a magnetic resonance unit, a magnetic resonance unit, and a computer program product are provided. The method includes acquiring positioning data relating to the examination object using an acquisition unit. Using the acquired positioning data, positioning information relating to the examination object is determined using an analysis unit. Evaluation information is determined using the positioning information, using an evaluation unit. Using the evaluation information, an evaluation signal is transmitted using an output unit. Monitoring of a specific absorption rate may be adjusted using the evaluation signal.

Evaluation of the positioning of an examination object

In a magnetic resonance (MR) apparatus and an operating method therefor, a sequence with which the MR data are to be recorded is created in or provided to a control computer of the MR apparatus. A maximum RF output and a maximum gradient performance of the scanner magnetic resonance apparatus during the performance of the sequence are determined by simulating or analyzing the performance of the sequence in the control computer, and it is verified whether the maximum RF output and/or the maximum gradient performance violate predetermined limit values. Execution of the sequence to record the MR data is performed only if the verification showed that the limit values are not violated.

Method and magnetic resonance apparatus wherein limit values are observed when recording magnetic resonance data

A method for operating a magnetic resonance apparatus by a safety unit, taking into account persons fitted with an implant, a safety unit, a safety system, a magnetic resonance apparatus, and a computer program product are provided. The magnetic resonance apparatus includes a first part and a second part. The first part is operated separately from the second part and includes the safety unit. During an examination of a person fitted with an implant, the safety unit checks that the magnetic resonance apparatus, in a restricted operating mode, is complying with implant-conformant limit values.

Operation of a magnetic resonance apparatus taking into account persons fitted with implants

A predetermined reference object is arranged in a scan volume of a magnetic resonance system. In the scope of adjustment measurements, the reference object is respectively exposed by a radiofrequency transmitter antenna to an adjustment pulse. Using at least one radiofrequency receiver antenna, a magnetic resonance signal excited by the respective adjustment pulse in the reference object is respectively recorded. An amplitude of a first test pulse is ascertained with the aid of the magnetic resonance signals recorded in the scope of the adjustment measurements. In the scope of a subsequent test measurement, the reference object is exposed to the first test pulse by the radiofrequency transmitter antenna. A first measurement signal dependent on the amplitude of the first test pulse is recorded during the exposure of the reference object to the first test pulse. Further measures are implemented based on the recorded first measurement signal.

Magnetic resonance system with RF power measurement check using a calibrated test pulse

The embodiments relate to devices and methods for MRT imaging with a MRT, where a patient table having the scan subject is moved in at least one direction along at least one displacement path, determination of a quantity representing the SAR effect on the scan subject being carried out at a plurality of positions along the displacement path, a suitable position of the patient table, lying on a displacement path, being determined, at which the MRT imaging of the scan subject imaging region, to be scanned, of the scan subject is subsequently intended to be carried out.

Optimization of specific absorption rate performance

In a method to operate an image-generating medical modality in order to avoid harm to a patient caused by an electromagnetic field, an adjustment process is implemented in which the electromagnetic field is radiated by the modality and preliminary image data are acquired using the electromagnetic field; and a clearance between the patient and a wall of the modality is determined from the image. The determined clearance forms the basis of a check process to determine an adaptation of the electromagnetic field for a diagnostic examination of the patient that follows. During the diagnostic examination, that also includes radiation of the electromagnetic field, movement monitoring of the patient takes place and the adjustment process is restarted as soon as a movement of the patient is registered.

Method to operate an image-generating medical modality to avoid patient injury by a modality-generated electromagnetic field

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.

Method and device for selecting body model positions for SAR monitoring of a magnetic resonance transmit array

In a the method for determining distortions in an image that can be generated with an imaging system from a subject arranged in an imaging volume of the imaging system, a first region of the imaging volume is presented undistorted in the image and a second region of the imaging volume is presented distorted in the image. Using the imaging system, an image of at least three markings that have a known spatial position relative to one another is produced. A first and a second of the three markings are arranged in the first region and a third of the three markings is arranged in the second region. The position of the imaged markings in the image is determined. An ideal position of the third marking in the image is determined from its known spatial arrangement with respect to the first and second markings. A positional difference of the imaged third marking from its ideal position is identified. The positional difference represents a criterion for the distortion.

Method for determining distortions in an image and calibration object therefor

In a method and apparatus for magnetic resonance imaging with adherence to SAR limit values, a patient is subjected to a radio-frequency pulse sequence via at least one transmission antenna and the magnetic resonance signals that are produced are acquired in a spatially resolved manner via at least one reception antenna and are further-processed for producing magnetic resonance images or spectra, with current SAR values, determined before the implementation of the measurement on the basis of patient data and the position of the patient relative to the transmission antenna for planned parameters of the measurement, being modified as warranted until the current SAR values lie within the SAR limit values. The determination of the current SAR values ensues by comparing the current measurement situation to pre-defined measurement situations stored in a data bank for which pre-calculated SAR values are stored. The stored SAR value of the measurement situation of the data bank coming closest to the current measurement situation is utilized as the current SAR value. A reduction of the calculating outlay for determining the SAR values during the examination is achieved, and the data bank values can be calculated highly detailed, allowing a more exact determination of the current SAR values. The reduction of the safety margins that is achieved allows an enhancement of the system performance for the user, so that the user can implement the measurements in a shorter time and/or simultaneously acquire a number of tomograms.

Magnetic resonance imaging apparatus and method with adherence to SAR limits

In a method and apparatus for magnetic resonance imaging with adherence to SAR limits, a patient is exposed to a radio-frequency pulse sequence via at least one transmission antenna for the implementation of a measurement and the magnetic resonance signals that are generated are acquired in a spatially resolved manner via at least one reception antenna and are further-processed for generating magnetic resonance images or spectra, with current SAR values for planned parameters of the measurement being identified before the implementation of the measurement and the parameters being modified as needed until the current SAR values lie within the SAR limits. The determination of the current SAR values ensues employing stored data that contain the time curve of the RF stressing of the patient during one or more preceding measurements, as well as information from which the temporal spacing of the RF stress of the preceding measurements from the planned measurement can be determined. Better utilization of the performance capability of the magnetic resonance tomography apparatus is achieved by the patient throughput, which is of particular interest for economic feasibility, being increased with adherence to the SAR limit values.

Magnetic resonance imaging method and apparatus with adherence to SAR limits in a scan using data from a previous scan

In a method for magnetic resonance imaging with adherence to SAR limit values, a patient is charged with a radio-frequency pulse sequence via at least one transmission antenna for the implementation of a measurement in a magnetic resonance tomography apparatus, and the magnetic resonance signals that are produced are acquired in a spatially resolved manner via at least one reception antenna and are further-processed for producing magnetic resonance images or spectra. SAR values are determined before the implementation of the measurement on the basis of patient data and the position of the patient relative to the transmission antenna for planned parameters of the measurement, and the parameters are modified as needed until the SAR values lie within the SAR limit values. The position of the patient relative to the transmission antenna is exactly determined by an imaging magnetic resonance pre-measurement. The method enables adherence to the SAR limit values without having to take large tolerances into consideration. No additional hardware whatsoever and no positioning rule for the user are required for the realization of the method.

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Erlangen, Germany

Gerhard Brinker