In a method for simultaneous generation of measurement data of at least two subvolumes of an examination object by means of a slice multiplexing EPI-method, after an RF excitation pulse, at least three navigator signals, but a total of at least one navigator signal per possible polarity and per subvolume to be simultaneously recorded, are recorded in the absence of phase encoding gradients. From the recorded navigator signals, subvolume-specific correction data is determined, which can be used in a reconstruction of image data from acquired raw data for correcting shifts caused by phase errors in the MR raw data.

Described here are systems and methods for correcting magnetic resonance data for off-resonance effects arising from the use of a multi-echo echo planar imaging (EPI) pulse sequence. Reference data are acquired, from which phase maps are computed in a distorted coordinate space associated with geometric distortions associated with the multi-echo EPI acquisition. Images reconstructed from the magnetic resonance data are demodulated using the distorted phase maps to produce distortion free images of the subject. Advantageously, the systems and methods can be used to reconstruct distortion free images from magnetic resonance data that is otherwise prone to image distortions from off-resonance errors, including data acquired from hyperpolarized nuclear spin species such as hyperpolarized carbon-13.

Methods, devices, systems and apparatus for dynamic imaging based on echo planar imaging (EPI) sequence are provided. In one aspect, a method includes: obtaining first pre-scanned k-space data by performing a pre-scan for a subject based on a first EPI sequence and pre-scanning parameters, obtaining a pre-scanned image and second pre-scanned k-space data according to the first pre-scanned k-space data, performing a dynamic scan for the subject based on a second EPI sequence and dynamic scanning parameters to generate dynamically-scanned k-space data associated with each of a plurality of dynamic periods in the dynamic scan, and for each of the dynamic periods, generating a residual image according to the dynamically-scanned k-space data of the dynamic period and the second pre-scanned k-space data, and adding the pre-scanned image and the residual image to obtain a dynamic image of the dynamic period.

Disclosed herein are a method and an apparatus for removing ghost artifacts of an echo planner image using a neural network. An image processing method according to an embodiment of the inventive concept includes receiving Fourier space data of an echo planar image, and restoring the echo planar image in which ghost artifacts are removed using a neural network. The receiving of the Fourier space data may include dividing the Fourier space data into the odd-numbered Fourier space data and even-numbered Fourier space data, and the restoring of the echo planar image may include obtaining the odd-numbered Fourier space data and even-numbered Fourier space data with the Fourier space interpolated using the neural network and restoring the echo planar image in which the ghost artifacts are removed based on the odd-numbered Fourier space data and even-numbered Fourier space data with the Fourier space interpolated.

Methods and systems are provided for hybrid slice encoding. In one embodiment, a method for magnetic resonance imaging comprises, during a scan with a pulse sequence, sampling k-space linearly for a predetermined number of echoes, and sampling k-space centrically for remaining echoes of the pulse sequence. In this way, blurriness along the slice direction may be reduced for 3D fast spin echo imaging.

A method and system for reducing Nyquist ghost artifact is provide. The method may include: obtaining a plurality of measured data sets; determining, based on the plurality of measured data sets, in a data space, a plurality of convolution kernels, each convolution kernel relating to all of the plurality of measured data sets; generating, based on the plurality of convolution kernels and the plurality of measured data sets, in the data space, a plurality of synthetic data sets; generating, based on the plurality of synthetic data sets and the plurality of measured data sets, in the data space, a plurality of combined data sets, each combined data set relating to one of the plurality of synthetic data sets and a corresponding measured data set of the plurality of measured data sets; and reconstructing, based on the plurality of combined data sets, an image.

A nuclear magnetic resonance (NMR) apparatus includes a carrier configured to be deployed in a borehole, a magnet assembly configured to generate a static magnetic field in an earth formation, and at least one transmitting assembly configured to generate an oscillating magnetic field in a volume of interest within the formation. The apparatus also includes a pulse generator configured to apply a direct-echo pulse sequence to the at least one transmitting assembly, the direct-echo pulse sequence having a plurality of successive pulses including a first pulse and a second pulse configured to generate a first direct NMR echo, and a third pulse, the third pulse selected to at least partially separate a stimulated NMR echo from a second direct NMR echo occurring after the third pulse. The apparatus further includes at least one receiving assembly configured to detect the first and second direct echoes of an NMR echo train.

The invention provides for a magnetic resonance imaging system (100) for acquiring preliminary magnetic resonance data (144, 146) from an imaging zone (108). The magnetic resonance imaging system comprises: a memory (134) for storing machine executable instructions (140) and preparation pulse sequence commands (142). The preparation pulse sequence commands are configured for controlling the magnetic resonance imaging system to acquire the preliminary magnetic resonance data as a first data portion (144) and a second data portion (146). The preparation pulse sequence commands configured for controlling the magnetic resonance imaging system to generate a first bipolar readout gradient during acquisition of the first portion. The preparation pulse sequence commands configured for controlling the magnetic resonance imaging system to generate a second bipolar readout gradient during acquisition of the second portion. The first bipolar readout gradient has an opposite polarity to the second bipolar gradient. The magnetic resonance imaging system further comprises a processor (130) for controlling the magnetic resonance imaging system. Execution of the machine executable instructions causes the processor to: control (200) the magnetic resonance imaging system with the preparation pulse sequence commands to acquire the first data portion and the second data portion; calculate (202) a measured normalised phase correction quantity (152) in image space using the first data portion and the second data portion; and fit (204) a modeled phase correction (154) to the measured phase error, wherein the modeled phase correction is an exponential of a complex value multiplied by a phase error function (156), wherein the phase error function is spatially dependent.

A magnetic resonance imaging (MRI) system, method and/or computer readable medium is configured to effect improved parallel MR imaging with reduced unfolding artifacts by using either or both of: (a) an unfolded intermediate diagnostic image to create a more accurate mask for use in further processing raw image data for final unfolded diagnostic images; and/or (b) an extension of coil sensitivity maps by replication (rather than curve-fitted extrapolation) for use in final unfolding of diagnostic images.

To perform Dixon MRI, generate multi-contrast images, and extract multi-parametric maps, this invention presents a multi-echo gradient echo protocol with two sets of echo trains. An example implementation of the invention at 3 T acquires a short-TE train (TE1.2 ms, TE<10 ms), which is used to map B0 inhomogeneity and proton density fat fraction (FF), and a secondsusceptibility sensitivelong-TE train (16 ms<TE<45 ms) will enable quantification of local frequency shift (LFS) and susceptibility. The presented pipeline automatically generates co-registered images and maps with/without fat-suppressed, including magnitude- and complex-based FF map, B0 map, anatomical images, brain mask, R2* map, unwrapped phase maps for each echo, susceptibility-sensitive images (SWI, LFS and quantitative susceptibility) for each echo, mean susceptibility-sensitive images for each echo-train. The invention is directly applicable to whole head/neck, liver, knee or even whole body scans with sliding table.