摘要:
A method for activating a magnetic resonance system having a transmit antenna arrangement is provided. The transmit antenna arrangement includes a plurality of independent high-frequency transmit channels with a respectively assigned transmit antenna. Each high-frequency transmit channel has a controllable oscillator. The individual high-frequency transmit channels are activated with independent transmit pulses, and a frequency of the controllable oscillators is controlled independently. At least two of the controllable oscillators therefore oscillate in different frequencies.
摘要:
In a magnetic resonance (MR) apparatus and an operating method for the apparatus, image distortions are corrected that occur in exposures of diffusion-weighted MR images of an examination subject.A diffusion-weighted image is acquired using a first acquisition process.Another diffusion-weighted reference image is acquired using a second acquisition process that is different than the first acquisition process.The second acquisition process causes significantly smaller eddy current-dependent image distortions than the first acquisition process given the same b-value.Correction parameters to correct the image distortions of the diffusion-weighted image are determined by comparing the diffusion-weighted image with the reference image in order to determine the correction parameters such that the diffusion-weighted image can be converted into the reference image with the aid of the correction parameters.
摘要:
In an imaging system having a number of subsystems and a control device that controls the subsystems in a coordinated manner to implement a measurement sequence and an operating method therefor, sequence control data that define different functional sub-sequences of the measurement sequence are transmitted to the control device. Different active volumes are associated with the functional sub-sequences. In addition to the sequence control data, active volume position data are provided to the control device that define bearing and extent of the active volumes associated with the different functional sub-sequences. Control signals to implement the measurement sequence for the different subsystems are generated automatically by the control device based on the sequence control data and the active volume position data so that the individual functional sub-sequences are locally optimized at least with regard to a sub-region of their associated active volume.
摘要:
In a method and apparatus to generate a magnetic resonance (MR) image in a volume of interest of an examination subject, the magnetization is excited in an additional volume in the subject by at least one RF pulse, in order to achieve a desired magnetization in the volume of interest. The additional excitation volume differs at least partially from the volume of interest. For this purpose, at least one MR overview image of the examination subject is analyzed automatically to determine a position of at least one anatomical structure of the examination subject, from which the volume of interest is automatically determined. The additional excitation volume is automatically determined using the position of the at least one anatomical structure. The MR image in the volume of interest is acquired with excitation of the magnetization in the automatically determined additional excitation volume.
摘要:
In a method for diffusion-weighted acquisition of MR signals with an acquisition sequence that includes a diffusion module with multiple diffusion coding gradients and a readout module with readout gradients to acquire the MR signals, the acquisition sequence is configured to acquire MR signals that correspond to a predetermined signal coherence path. The method includes the acquisition of MR signals with the acquisition sequence, and the diffusion coding gradients are activated with predetermined gradient moments during the acquisition sequence. The gradient moments of the diffusion coding gradients are set such that MR signals that correspond to other coherence paths than the predetermined coherence path are reduced, wherein the adjustment of the gradient moments to achieve a predetermined reduction ensues on the basis of a threshold.
摘要:
In a method for correction of distortions in image data in a diffusion imaging, the image data are acquired with an imaging MRT measurement for a predetermined diffusion weighting and map a predetermined image segment. A diffusion model for the image segment is determined. Output image data are determined for the image segment such that the output image data are essentially free of distortions caused by diffusion weighting. Reference image data are estimated for the predetermined diffusion weighting for the image segment based on the output image data and the diffusion model. The acquired image data are compared with the reference image data and the acquired image data are corrected based on the comparison.
摘要:
An apparatus and method for obtaining diffusion weighted magnetic resonance images (DW-MRI) is described. The properties of the diffusion tensor in tissue are measured by applying a diffusion weighting gradient oriented along a plurality of measurement axes. The value of the magnetic field is increased by using as many of the magnetic gradient coils as are effective in contributing the gradient field strength along the axis being. In regions where the magnetic field gradient is increased, the echo time (TE) may be decreased, increasing the signal-to-noise ratio of the measurements. Alternatively, the number of measurements than are averaged to achieve a particular image quality may be decreased, reducing the patient exposure time.
摘要:
In a method and computerized device for determination of imaging parameters for the acquisition of a magnetic resonance image of an examination subject, initial imaging parameters are established, a calculation is made, based on the initial imaging parameters, of signal intensities for tissue types that occur at least in a portion of the examination subject, and the imaging parameters for the acquisition of the magnetic resonance image under are adapted dependent on the calculated signal intensities.
摘要:
A dielectric element is formed of a dielectric material exhibiting a magnetic resonance relaxation time, with a relaxation agent incorporated in the dielectric material that reduces the relaxation time of the dielectric material. The dielectric element is adapted for placement on a subject while magnetic resonance data are acquired from the subject, and locally influences the B1 field distribution in the subject during the acquisition of magnetic resonance data.
摘要:
A method is disclosed for recording measured data of a patient while taking account of movement operations by way of a medical device that is designed both for recording movement-related measured data, in particular measured data of high temporal resolution and/or measured data that can be interpolated with regard to movement operations, with the aid of an imaging method and/or by means of at least one sensor element, and also for recording nuclear medicine measured data, in particular of lower temporal resolution. In at least one embodiment, the method includes recording nuclear medicine measured data with the aid of the medical device; simultaneously recording movement-related measured data with the aid of the medical device; determining at least one item of movement information relating to at least one movement operation of the patient and/or in the body of the patient by evaluating at least a portion of the recorded measured data of high temporal resolution on the part of a computing device of the medical device; and adapting at least one item of attenuation correction information available for the computing device and serving for reconstructing the nuclear medicine measured data, doing so as a function of the at least one determined item of movement information.