A magnetic resonance (MR) system is provided. The MR system includes a gradient coil assembly and a concomitant field correction computing device. The at least one processor of the computing device is programmed to receive MR signals acquired with the MR system using a three-dimensional (3D) pulse sequence, wherein a kx dimension and a ky dimension in k-space are sampled along non-Cartesian trajectories. The at least one processor is further programmed to correct effects of concomitant fields generated by gradient fields applied by the gradient coil assembly by adjusting the MR signals with second-order concomitant phases accumulated from second-order concomitant fields, and reconstructing MR images based on the adjusted MR signals. The second-order concomitant phases vary as functions of time and spatial locations. The at least one processor is also programmed to output the MR images.

Acquiring 3D MRI data using spiral-in-out encoding trajectories includes calculating a variable flip angle RF series for use as refocusing pulses, wherein the RF series includes a plurality of refocusing RF pulses. A spoiler gradient waveform is applied along the spoiler gradient direction, wherein the computer alternately adds and subtracts partition encoding waveforms to the spoiler gradient waveform. The method reads MRI data from each encoding step during an MRI sequence. The MRI sequence inserts a spiral-in gradient before a first refocusing RF pulse from the RF sequence, overlaps a pre-winder lobe for the encoding trajectory with the spoiler gradient waveform having the partition encoding waveforms added therein, and overlaps a rewinder lobe for the encoding trajectory with the spoiler gradient waveform having the partition encoding waveforms subtracted there from.

Magnetic resonance (MR) data are acquired from a volume segment of an examination object and an MR image composed of multiple image pixels is reconstructed therefrom. For a magnetic field assumed to have been generated by the scanner, a summed field deviation is calculated, from which a respective displacement vector is calculated for each image pixel. A signal portion is assigned to each image pixel that has been displaced with the respective displacement vector from the respective image pixel. The summed field deviation is the sum of deviations caused by at least two of: non-linearities in gradient coils, Maxwell fields, field inhomogeneities independent of the gradients, and dynamic field disturbances.

In a method to correct a signal phase in the acquisition of MR signals of an examination subject in a slice multiplexing method, in which MR signals from at least two different slices of the examination subject are detected simultaneously in the acquisition of the MR signals, a linear correction phase in the slice selection direction is determined for each of the at least two slices. An RF excitation pulse with a slice-specific frequency is radiated in each of the at least two different slices. A slice selection gradient is activated during a slice selection time period, during which the different RF excitation pulses are radiated in the at least two different slices, and the slice selection time period has a middle point in time in the middle of the slice selection time period, and the different RF excitation pulses temporally overlap for the at least two different slices. A time offset of the RF excitation pulse relative to the middle point in time for each of the RF excitation pulses is determined, such that a slice-specific correction gradient moment in the slice selection direction that corresponds to the linear correction phase of the respective slice acts on the magnetization of the respective slice.

In a method and device for generating 4D flow images by operation of a magnetic resonance system, a volume flow data record is recorded, wherein the flow is encoded in a single direction. This is subsequently repeated with all the flow encoding directions. From the raw data associated with the individual flow encoding directions, phase images and magnitude images are calculated. Deformation fields are calculated on the basis of the magnitude images. The deformation fields are applied to the calculated phase images. Finally, a 4D flow velocity field is calculated, on the basis of a phase difference reconstruction of the corrected phase images.

A magnetic resonance (MR) system is provided. The MR system includes a gradient coil assembly and a concomitant field correction computing device. The at least one processor of the computing device is programmed to receive MR signals acquired with the MR system using a three-dimensional (3D) pulse sequence, wherein a kx dimension and a ky dimension in k-space are sampled along non-Cartesian trajectories. The at least one processor is further programmed to correct effects of concomitant fields generated by gradient fields applied by the gradient coil assembly by adjusting the MR signals with second-order concomitant phases accumulated from second-order concomitant fields, and reconstructing MR images based on the adjusted MR signals. The second-order concomitant phases vary as functions of time and spatial locations. The at least one processor is also programmed to output the MR images.

Systems and methods for performing concomitant field corrections in magnetic resonance imaging (MRI) systems that implement asymmetric magnetic field gradients are provided, in general, the systems and methods described here can correct for the effects of concomitant fields of multiple orders, such as zeroth order, first order, and second order concomitant fields.

During operation, a computer system may acquire magnetic resonance (MR) signals associated with a sample from a measurement device or memory. Then, the computer system may access a predetermined set of coil magnetic field basis vectors associated with a surface surrounding the sample, where coil sensitivities of coils in the measurement device are represented by weighted superpositions of the predetermined set of coil magnetic field basis vectors using coefficients, and where the predetermined coil magnetic field basis vectors are solutions to Maxwell's equations. Next, the computer system may solve, on a voxel-by-voxel basis for voxels associated with the sample, a nonlinear optimization problem for MR information associated with the sample and the coefficients using: a forward model that uses the MR information as inputs and simulates response physics of the sample, the MR signals and the predetermined set of coil magnetic field basis vectors.

Systems and methods for correcting magnetic resonance (MR) data are provided. One method includes receiving the MR data and correcting errors present in the MR data due to non-uniformities in magnetic field gradients used to generate the diffusion weighted MR signals. The method also includes correcting errors present in the MR data due to concomitant gradient fields present in the magnetic field gradients by using one or more gradient terms. At least one of the gradient terms is corrected based on the correction of errors present in the MR data due to the non-uniformities in the magnetic field gradients.

A method according to the invention for the slice-specific adjustment of RF pulses when recording MR signals of an examination subject with the use of a slice multiplexing method in which MR signals from at least two different slices of the examination subject are detected simultaneously when recording the MR signals, has the following steps. The respective position of the slices to be simultaneously detected in the examination subject are determined and designated in a processor. For each slice to be detected simultaneously, monoslice RF pulse parameters are determined in the processor based on the determined position of the respective slice. The monoslice RF pulse parameters are corrected in the processor based on at least one examination subject-specific parameter map, which maps the spatial distribution of a system parameter in the examination subject, and the determined position. A multiband RF pulse is determined in the processor, for manipulation of the slices to be detected simultaneously based on the corrected monoslice RF pulse parameters. An electronic signal is emitted by the processor that represents the RF pulse, in a form useable to operate the MR scanner in the acquisition of the MR signals.