The present disclosure relates to operating an MR system in which MR signals of an object under examination are acquired in an examining region using a multi echo imaging sequence, in which an RF excitation pulse and a plurality of RF refocusing pulses are applied. The techniques include determining a first accumulated phase of a magnetization in the object under examination. Then, a second accumulated phase of the magnetization in the object under examination is determined due to concomitant magnetic fields occurring between a second pair of consecutive RF pulses. Finally, it is determined whether a deviation from the predefined relationship is larger than a threshold and, if this is the case, a measure is applied in view of the fact that the deviation is larger than the threshold.

Techniques are disclosed for ascertaining a point spread function (PSF) for reconstructing image data from scan data recorded by means of a magnetic resonance system. The techniques include a comparison of values determined for a planned k-space trajectory for parameters characterizing the k-space trajectory with baseline values of the parameters characterizing the k-space trajectory deposited in a database for the magnetic resonance system, in each case together with an associated point spread function PSF to ascertain baseline values of the deposited baseline values that are as similar as possible to the values determined for the planned k-space trajectory for the parameters characterizing the k-space trajectory and, on the basis of this deposited PSF, a PSF to be used for a reconstruction of final image data is ascertained.

The present disclosure is directed to MRI techniques. The techniques include occupying a central region of a first k-space with full sampling along a Cartesian trajectory, occupying a peripheral region of the first k-space with undersampling along a non-Cartesian trajectory; acquiring sensitivity distribution information of receiving coils; based on a sensitivity distribution chart, merging the Cartesian data of the central region according to multiple channels to obtain a third k-space; based on the sensitivity distribution chart, applying parallel imaging and compressed sensing to the undersampled non-Cartesian trajectory to reconstruct an image, obtaining a second k-space by transformation, and when the second k-space and third k-space are synthesized, using a central region of the second k-space to replace the third k-space of a corresponding region to obtain a k-space suitable for image reconstruction.

Embodiments of the present application provide a magnetic resonance system and a shimming method and an imaging method thereof. The shimming method comprises: performing a scout scan on a subject to be examined, and obtaining phase data of a plurality of slice positions; determining three-dimensional space static magnetic field information according to the phase data of the plurality of slice positions; and determining a shimming value of a slice in a region of interest according to the three-dimensional space static magnetic field information.

A system and method for correcting phase shift in echo images are provided. The method may include one or more of the following operations. A plurality of echo images may be obtained. Homogeneous pixels in the plurality of echo images may be identified. A vector corresponding to each of at least some of the identified homogeneous pixels may be determined. A vector of a homogenous pixel includes a phase element and an amplitude element. A first complex linear model of phase shift may be determined based at least in part on the determined vectors. Phase shift of at least one of the plurality of echo images may be corrected based on the first complex linear model.

A method for accelerating diffusion magnetic resonance imaging (MRI) acquisition via slice interleaved diffusion encoding (SIDE) includes conducting a plurality of simultaneous multislice (SMS) excitations for each of a plurality of SIDE diffusion-weighted volumes to obtain SMS images of an MRI subject at different diffusion orientations, regrouping the images into slice groups with different orientations, generating a plurality of slice-undersampled diffusion weighted volumetric images of the subject, wherein each of the plurality of slice-undersampled diffusion weighted volumetric images is produced by cyclically interleaving the slice groups, such that each slice group is associated with a different diffusion wavevector, and reconstructing a full diffusion-weighted volumetric image of the subject by providing the plurality of slice-undersampled diffusion weighted volumetric images to a neural network trained to produce full diffusion-weighted volumetric versions of diffusion magnetic resonance images from undersampled versions of the diffusion magnetic resonance images.

In a method for correcting influences on magnetic resonance imaging of an examination object caused by fluctuations in a basic magnetic field, an MR data set is generated for two or more measurement periods, and a regression analysis is performed. Each of the MR data sets may contain at least one two-dimensional individual data set. The regression analysis may determine at least one phase correction value for a measurement period to be corrected. Two or more different individual data sets may be taken into account in the analysis. An MR image may generated based on the MR data sets and the at least one phase correction value.

A method for performing magnetic resonance imaging on a subject comprises obtaining undersampled imaging data, extracting one or more temporal basis functions from the imaging data, extracting one or more preliminary spatial weighting functions from the imaging data, inputting the one or more preliminary spatial weighting functions into a neural network to produce one or more final spatial weighting functions, and multiplying the one or more final spatial weighting functions by the one or more temporal basis functions to generate an image sequence. Each of the temporal basis functions corresponds to at least one time-varying dimension of the subject. Each of the preliminary spatial weighting functions corresponds to a spatially-varying dimension of the subject. Each of the final spatial weighting functions is an artifact-free estimation of the one of the one or more preliminary spatial weighting functions.

A method for magnetic resonance imaging corrects non-stationary off-resonance image artifacts. A magnetic resonance imaging (MRI) apparatus performs an imaging acquisition using non-Cartesian trajectories and processes the imaging acquisitions to produce a final image. The processing includes reconstructing a complex-valued image and using a convolutional neural network (CNN) to correct for non-stationary off-resonance artifacts in the image. The CNN is preferably a residual network with multiple residual layers.

An apparatus and a method for generating a volume-selective three-dimensional magnetic resonance image are disclosed. The volume-selective three-dimensional magnetic resonance image generating method according to an exemplary embodiment of the present disclosure includes applying a frequency selective excitation pulse and a slab selection gradient magnetic field together to an object; acquiring a signal generated from the object by the excitation pulse and the slab selection gradient magnetic field; and generating a three-dimensional magnetic resonance image through encoding based on a readout gradient magnetic field maintaining vertically to the acquired signal and the slab selection gradient magnetic field.