A method for measuring concomitant fields in a magnetic resonance (MR) system is provided. The method includes applying a measurement pulse sequence in a plurality of acquisitions. Applying the measurement pulse sequence further includes applying a first bipolar gradient pulse in a first acquisition, applying a second bipolar gradient pulse in reverse polarities from the first bipolar gradient pulse in a second acquisition, and applying the measurement pulse sequence without a bipolar gradient pulse in a third acquisition. The method further includes acquiring MR signals emitted from the subject, and generating phase images based on the MR signals. The method also includes generating volumetric vector field maps based on the phase images, wherein the volumetric vector field maps include concomitant field at each spatial location in a 3D volume, the concomitant field represented as a vector. In addition, the method includes outputting the volumetric vector field maps.

In diffusion-weighted magnetic resonance imaging, diffusion-encoded gradient pulses with an amplitude and a duration are activated. The amplitude and the duration of the gradient pulses are varied for various excitations of nuclear magnetization. The echo time for the various excitations of nuclear magnetization can be changed.

In a magnetic resonance (MR) method system for slice-selective detection and correction of incorrect magnetic resonance data, a first acquisition sequence is implemented to acquire MR data from a first slice of the examination subject that is associated with a chronologically first coherence curve of the magnetization; a second acquisition sequence is implemented to acquire MR data from a second slice of the examination subject that is associated with a chronologically second coherence curve of the magnetization. In slice multiplexing measurement sequences that are characterized by the simultaneous use of the transverse magnetization of the first and second slice within the first and second acquisition sequences slice-selective errors can be detected and corrections made.

In a method and apparatus for acquiring magnetic resonance (MR) data, MR signals are acquired simultaneously from N slices of a subject with an SMS factor of S, the N slices respectively being at different positions from an isocenter of the data acquisition scanner, thereby causing said MR signals to be affected differently by Maxwell terms of magnetic fields that give said MR signals respective signal dephasings that are dependent on the distance of a respective slice from the isocenter. The SMS MR data acquisition sequence is executed with a spacing between each pair of adjacent slices being less than or equal to N/2S. A Maxwell correction algorithm is applied to the acquired k-space data by calculating Maxwell correction gradient moments at an average position between each pair of adjacent slices, thereby generating corrected k-space data wherein the signal dephasing of the MR signals from the N slices is reduced.

A magnetic resonance imaging (MRI) system, method and/or computer readable medium is configured to effect MR imaging with reduced artifact by generating one or more image reconstruction maps from one or more prescans, acquiring a main scan dataset from a main MRI scan of an object, warping one or more image reconstruction maps to have geometric distortions substantially corresponding to geometric distortions in the main scan dataset, and forming a diagnostic MR image of the object using the main scan dataset and the warped one or more image reconstruction maps.

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.

The present disclosure relates to a method of performing 3D Magnetic Resonance Imaging including applying a magnetic gradient field that causes a concomitant field B.sub.c. A further step of the method includes determining phase accruals due to the self-squared terms of the concomitant field B.sub.c and phase accruals .sub.xz, .sub.yz due to the cross terms of the concomitant field B.sub.c based on an encoding matrix that accounts for the different possible sign combinations of the applied magnetic gradients.

A magnetic resonance (MR) system for correcting concomitant field effects is provided. The MR system includes a gradient coil assembly including a plurality of gradient coils configured to apply at least one gradient field to a polarizing magnetic field of the MR system. The MR system also includes a second-order correction coil assembly including a first second-order correction coil configured to correct effects of a first term of second-order concomitant fields generated by the at least one gradient field. The system further includes a second-order correction computing device including at least one processor in communication with at least one memory device. The at least one processor is programmed to control the second-order correction coil assembly by instructing the MR system to apply a compensation field to the second-order correction coil assembly asynchronously with the at least one gradient field.

A method for operating a magnetic resonance facility is provided. The method includes generating a magnetic field using a magnet system. Measurement information is captured by a magnetic sensor. The measurement information relates to a stray magnetic field present outside an acquisition area and resulting from the magnetic field and an interference field. The method includes determining interference information relating to the interference field using the measurement information. The method includes compensating for or reducing the interference field in the acquisition area by changing the magnetic field using the interference information. In order to determine the interference information, a modeling of the interference field takes place using the measurement information. For the modeling, a field model describing a vector field for the interference field is used.