Siemens Aktiengesellschaft

Siemens Healthcare Gmbh

Franz Hebrank

Thorsten Speckner

Axel Vom Endt

Gerhard Brinker

Thorsten Feiweier

Matthias Gebhardt

Wilfried Schnell

Helmut Lenz

Wilhelm Horger

Michael Koehler

Georg Frese

Mathias Blasche

Patrick Sieber

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

An RF pulse alignment method for determining transmit scaling factors used in the control of a magnetic resonance system having a number of radiofrequency transmit channels, via which RF pulse trains are transmitted in parallel during operation, is provided. A common reference pulse train is specified for a number of the radiofrequency transmit channels in the course of the control function. A plurality of candidate images of an object that is to be examined are acquired using different candidate sets of transmit scaling factors. Optimal transmit scaling factors with respect to a predefined criterion are selected for each of the radiofrequency transmit channels based on the acquired candidate images.

RF pulse alignment

In a method and apparatus for acquiring a magnetic resonance image data set of a scan area of an examination subject, the image data are acquired with a magnetic resonance apparatus having a transmitter coil that emits a radio-frequency signal having at least two transmission channels so that different polarizations of the radio-frequency signal are produced, and a magnetic resonance sequence is used to acquire raw data for the magnetic resonance image data set, wherein raw data are acquired during at least two scanning operations with the magnetic resonance sequence, with different polarizations of the radio-frequency signals being used for at least two of the at least two scanning operations, following which the magnetic resonance image data set is determined by averaging the raw data.

Method and apparatus for acquiring a magnetic resonance image data set and magnetic resonance device

In one embodiment a method for processing a reconstruction image is disclosed. The method includes recording the reconstruction image by a magnetic resonance device having a gradient coil to generate a gradient field. The method further includes distortion-correcting the reconstruction image. The method further includes back-transforming the distortion-corrected reconstruction image, by an image processing device, into a distortion-uncorrected reconstruction image, the back-transforming uses an algorithm having a first input value describing a real gradient field given at a real measuring point of the signal.

Method for processing a distortion-corrected 2D or 3D reconstruction image recorded by a magnetic resonance device

In one embodiment a method for processing a reconstruction image is disclosed. The method includes recording the reconstruction image by a magnetic resonance device having a gradient coil to generate a gradient field. The method further includes distortion-correcting the reconstruction image. The method further includes back-transforming the distortion-corrected reconstruction image, by an image processing device, into a distortion-uncorrected reconstruction image, the back-transforming uses a first algorithm or a second algorithm including a second input value associated with the measurement signal, the second input value being a fictitious gradient field value associated with a distorted measuring point at which the measurement signal is processed, and the second input value is raised or lowered by a nonlinear field component of the real gradient field compared with a linear ideal gradient field.

In a method and magnetic resonance apparatus for compensation of contrast inhomogeneities in magnetic resonance images caused by spatial distributions of the radio frequency field associated with the radio frequency pulses that are emitted in order to acquire magnetic resonance (MR) data, multiple individual MR images of a particular region of a subject are recorded with different radio frequency pulse sequences leading to different flip angles. A common contrast-homogenized image for the affected region then is generated based on the different individual images, so that within the contrast-homogenized image, intensity variations due to a distribution of the flip angle are smaller than in the individual images, at least in some areas.

Method and magnetic resonance imaging apparatus for compensating contrast inhomogeneities in magnetic resonance images

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

A method or apparatus for the simulation of electrical stimulations in an examination subject which are generated by rapidly switched gradient fields of an MR device, and wherein aborting of the executed measuring sequence occurs given the crossing of a threshold value in an online monitoring, wherein the crossing of the threshold value is signaled prior to the execution of the measuring sequence in a look-ahead monitoring, at least one gradient signal G(t) is determined which is defined by the time characteristic of the gradient pulses, at least one first filtered gradient signal G,(t) is formed by filtering the gradient signal G(t) with a first filtering function f,(t) a stimulation signal Stim(t) is formed which describes the stimulation of the examination subject, from the first filtered gradient signal G,(t), and the stimulation signal Stim(t) is compared to a definable stimulation threshold value Stim,. If Stim,is exceeded an indicator indicating that a stimulation has occurred is emitted.

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Herzogenaurach, Germany

Franz Hebrank