The disclosure provides a modified EPI sequence for acquiring multi-shot and multi-echo images with interleaved blip-up and blip-down phase encoding; the blip-up and blip-down images are processed by topup in FSL to estimate the inhomogeneous main magnetic field B.sub.0 map that causes image distortions; the B.sub.0 map is then incorporated into the encoding matrix with a low rank constraint to form a joint reconstruction model; the joint reconstruction model is solved to obtain multiple distortion-free images; and the multiple distortion-free images are matched to dictionary to simultaneous acquire the quantitative T.sub.2 (=1/R.sub.2) and T.sub.2* (=1/R.sub.2*) maps. In the phantom and in-vivo measurements, the disclosed method rapidly acquires the comparable quantitative images within one hold-breath (for 20 s) to the conventional mapping method, thus providing important practical application value for evaluation of liver damage, iron level and cancer lesion.

A method for avoiding artifacts in measurement data captured using a magnetic resonance system which has a gradient unit. The method includes loading data which characterizes the gradient unit of the magnetic resonance system; loading a measurement protocol to be used for capturing the measurement data, wherein the measurement protocol includes gradients to be switched and RF excitation pulses and RF refocusing pulses to be irradiated, wherein, after irradiation of an RF excitation pulse, a train of at least two RF refocusing pulses is irradiated and measurement data is captured after each RF refocusing pulse; determining compensation gradients which, after the capture of the measurement data, are to be switched after a final RF refocusing pulse of the train of RF refocusing pulses associated with the RF excitation pulse and before a following RF excitation pulse as a function of the loaded measurement protocol and of the data which characterizes the gradient unit; and carrying out the measurement protocol using the determined compensation gradients.

Methods for reconstructing images from undersampled k-space data using a machine learning approach to learn non-linear mapping functions from acquired k-space lines to generate unacquired target points across multiple coils are described.

An information processing apparatus according to an embodiment of the present disclosure includes a processing circuitry. The processing circuitry obtains a first g factor generated by using first magnetic resonance data acquired through a first parallel imaging process performed by using a plurality of reception coils and a second g factor generated by using second magnetic resonance data related to a second parallel imaging process performed by using the plurality of reception coils. The second parallel imaging process is different from the first parallel imaging process. The processing circuitry adjusts the first g factor so as to reduce a difference between the first g factor and the second g factor.

Techniques are disclosed for use in magnetic resonance imaging (MRI) for exciting spins of a first material and spins of a second material. A first spin echo signal is acquired when the excited spins include a first phase difference, which is given by Δ, and a second spin echo signal is acquired when the excited spins of the first material and the excited spins of the second material include a second phase difference, which is given by −Δ. An absolute value of Δ lies within the interval ]0,π[. A first image for the first material and/or a second image for the second material is generated by a computing unit depending on the first spin echo signal and the second spin echo signal.

The invention relates to a method of MR imaging of an object (10). It is an object of the invention to enable MR imaging in the presence of motion of the imaged object, wherein full use is made of the acquired MR signal and a high-quality MR image essentially free from motion artefacts is obtained. The method of the invention comprises the steps of: generating MR signals by subjecting the object (10) to an imaging sequence comprising RF pulses and switched magnetic field gradients; acquiring the MR signals as signal data over a given period of time (T); subdividing the period of time into a number of successive time segments (SO, S1, S2, . . . Sn); deriving a geometric transformation (DVF1, DVF2, . . . DVFn) in image space for each pair of consecutive time segments (S0, S1, S2, . . . Sn), which geometric transformation (DVF1, DVF2, . . . DVFn) reflects motion occurring between the two time segments of the respective pair; and reconstructing an MR image from the signal data, wherein a motion compensation is applied according to the derived geometric transformations (DVF1, DVF2, . . . DVFn). Moreover, the invention relates to an MR device (1) and to a computer program for an MR device (1).

An MRI system coil insert 2 for use within a bore B of a main MRI system 1, the coil insert 2 comprising at least one gradient coil, for creating a spatially varying magnetic field along a respective axis and being arranged to be electrically driven at an ultrasonic frequency.

An MRI system coil insert 2 for use within a bore B of a main MRI system 1, the coil insert 2 comprising at least one gradient coil, for creating a spatially varying magnetic field along a respective axis and being arranged to be electrically driven at an ultrasonic frequency.

The invention relates to a method of MR imaging of an object (10) placed in an examination volume of an MR apparatus (1). It is an object of the invention to enable fast 3D MR imaging that provides motion-compensation and also allows a precise compensation for system imperfections. The method of the invention comprises the steps of: —subjecting the object (10) to a number of shots (S1-S4) of a 3D imaging sequence, wherein a train of MR signals is generated by each shot (S1-S4), each MR signal representing a k-space profile, wherein the set of k-space profiles of each shot (S1-S4) comprises at least one navigator profile and a number of imaging profiles; —acquiring the MR signals; —deriving motion information from the at least one navigator profile; and —reconstructing an MR image from the imaging profiles, wherein a motion-compensation is applied based on the motion information. Motion-induced phase errors can be derived from the navigator profiles, wherein the motion-compensation involves a corresponding phase-correction. Further, phase errors caused by magnetic field gradient imperfections and/or eddy currents can be derived from the navigator profiles and a corresponding phase-correction can be applied during image reconstruction. Moreover, the invention relates to an MR apparatus (1) for carrying out this method as well as to a computer program to be run on an MR apparatus (1).

Nyquist ghost artifacts in echo planar imaging (“EPI”) are mitigated, reduced, or otherwise eliminated by implementing robust Nyquist ghost correction (“NGC”) directly from two reversed readout EPI acquisitions. As one advantage, these techniques do not require explicit reference scanning A model-based process is used for directly estimating statistically optimal NGC coefficients from multi-channel k-space data.