In a method and system for acquiring measurement data reference data for a phase correction of the measurement data, a RF excitation pulse is provided to excite spins in the object under examination, one or more RF refocusing pulses are provided to refocus the spins excited by the RF excitation pulse, measurement data is acquired by recording echo signals of refocused spins excited by the RF excitation pulse by switching readout gradients that alternate in their polarity, at least two echo signals are recorded while switching readout gradients with different polarity acquire reference data, chronologically between the providing of the RF excitation pulse and the acquisition of the measurement data, and correction data is determined for phase correction of phase errors contained in the measurement data based on the acquired reference data.

Techniques are disclosed for determining calibration data for a reconstruction of image data from scan data acquired by means of a magnetic resonance system. The techniques include specifying acquisition shots for an acquisition of desired scan data in which acquisition shots scan data is acquired after radiating-in an RF excitation pulse, identifying first acquisition shots among the acquisition shots specified in which scan data is acquired in a central region in k-space, stipulating a sequence in which the specified acquisition shots are to be carried out such that first acquisition shots are arranged in the sequence in a starting portion to be carried out first, acquiring the scan data by carrying out the specified acquisition shots in the stipulated sequence, determining calibration data from scan data acquired in the starting portion of the sequence, and reconstructing image data using the acquired scan data and the specified calibration data.

The disclosure relates to a method for generating a B.sub.0 map for a magnetic resonance examination of an examination subject, a magnetic resonance device, and a computer program product for executing the method. The method provides for the application of at least two preparatory RF pulses during a preparatory stage and at least one readout RF pulse during an acquisition stage. At least one stimulated echo signal is acquired after the readout RF pulse. A B.sub.0 map that shows the actual spatial distribution of the magnetic field strength of the main magnetic field is derived from the at least one acquired FID echo signal and the at least one acquired stimulated echo signal.

A method for k-space registration is provided. The method of k-space registration includes receiving a first partial k-space dataset for an object and a second partial k-space dataset for the object, selecting the first partial k-space dataset as a reference, selecting feature for estimating a transformation matrix for transforming k-space data, estimating a transformation matrix based on the feature of entire or part of the first partial k-space dataset and the feature of the second partial k-space dataset corresponding to the entire or part of the first partial k-space dataset, correcting the second partial k-space dataset based on the transformation matrix, and obtaining the corrected second partial k-space dataset. The present method is further used for partial Fourier reconstruction.

An asymmetric electromagnet system, method, and method of producing an asymmetric electromagnet system, wherein the asymmetric electromagnet system is for generating an imaging magnetic field in an imaging region with an imaging isocentre, the imaging region being asymmetrically positioned within a gradient coil bore inside a magnetic resonance imaging (MRI) system during imaging, the electromagnet assembly comprising: an asymmetric gradient coil configured to generate a gradient field in the asymmetrically positioned imaging region, at least one gradient axis having the gradient field with a constant offset component such that the position at which the gradient field passes through zero is offset with respect to the imaging isocentre of the asymmetrically positioned imaging region.

An apparatus for controlling at least one gradient coil of a magnetic resonance imaging (MRI) system. The apparatus may include at least one computer hardware processor; and at least one computer-readable storage medium storing processor executable instructions that, when executed by the at least one computer hardware processor, cause the at least one computer hardware processor to perform a method. The method may include receiving information specifying at least one target pulse sequence; determining a corrected pulse sequence to control the at least one gradient coil based on the at least one target pulse sequence and a hysteresis model of induced magnetization in the MRI system caused by operation of the at least one gradient coil; and controlling, using the corrected gradient pulse sequence, the at least one gradient coil to generate one or more gradient pulses for imaging a patient.

A method, device, and system for reducing inhomogeneity in an imaging magnetic field during magnetic resonance imaging is described. The method includes generating a corrective magnetic field during imaging, the corrective magnetic field having a first magnetic field component and a second magnetic field component with a phase separation therebetween. The first and second components are generated according to a stability parameter decomposed from a stability field that correct an instability identified within the imaging magnetic field.

Techniques are described for controlling a magnetic resonance imaging system to facilitate an improvement in Simultaneous Multislice Imaging, especially concerning a compensation of eddy currents. This is achieved by simultaneously measuring at least two slices by the magnetic resonance imaging system while applying a pulse sequence. In the course of the pulse sequence for measuring k-space lines, a set of in-plane encoding signals (that are typically gradients) are applied with a set of Hadamard encoding signals in an interleaved scheme.

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.

In one embodiment, an MRI apparatus includes a gradient coil, a receiving circuit, and processing circuitry. The gradient coil is configured to superimpose a gradient magnetic field on a static magnetic field. The receiving circuit is configured to receive an MR (magnetic resonance) signal from an object placed in the gradient magnetic field. The processing circuitry is configured to estimate time variation of an MR (magnetic resonance) frequency during a sampling period of the MR signal based on waveform data of a gradient current applied to the gradient coil, perform correction on a frequency or phase of the MR signal received by the receiving circuit based on the estimated time variation of the MR frequency during the sampling period, and reconstruct an image by using the MR signal subjected to the correction.