A system and method for magnetic resonance imaging reconstruction using novel k-space sampling sequences is provided. The method includes dividing k-space into a plurality of regions along a dividing direction; scanning an object using a plurality of sampling sequences; acquiring a plurality of groups of data lines; filling the plurality of groups of data lines into the plurality of regions of the k-space; and reconstructing an image based on the filled k-space.

A method is provided for performing NMR spectroscopy. The method comprises positioning a sample in a homogeneous stationary magnetic field directed along an axis, preparing nuclei in at least a predetermined volume of the sample for resonant emission of an NMR signal and creating this NMR signal. This comprises irradiating the sample with at least one RF excitation pulse in accordance with an MRI sequence preparation and/or evolution module. The method also comprises sensing the NMR signal in the absence of frequency encoding magnetic field gradients such that analysis of the NMR signal yields a chemical shift spectrum from the nuclei. During this sensing, a plurality of intermittently blipped phase gradient pulses are applied to incrementally shift a position in k-space such that different time segments of the NMR signal, demarcated by the blipped phase gradient pulses, correspond to different predetermined locations in k-space.

The invention relates to a method of Dixon-type MR imaging. The method comprises the steps of:subjecting the object (10) to a first imaging sequence (31) comprising a series of refocusing RF pulses, wherein a single echo signal is generated in each time interval between two consecutive refocusing RF pulses,acquiring the echo signals from the object (10) at a first receive bandwidth using unipolar readout magnetic field gradients,subjecting the object (10) to a second imaging sequence (32), which comprises a series of refocusing RF pulses, wherein a pair of echo signals is generated in each time interval between two consecutive refocusing RF pulses,acquiring the pairs of echo signals from the object (10) at a second receive bandwidth using bipolar readout magnetic field gradients, wherein the second receive bandwidth is higher than the first receive bandwidth, andreconstructing a MR image from the acquired echo signals, whereby signal contributions from water protons and fat protons are separated. Moreover the invention relates to a MR device (1) and to a computer program to be run on a MR device (1).

A method for MRI imaging of a subject includes spatially encoding spins in a slice of the subject in orthogonal first and second directions. The encoding includes applying a chirped radiofrequency (RF) pulse concurrently with application of a magnetic field gradient pulse along the first direction. After applying of the RF pulse, a second chirped RF pulse is applied concurrently with application of a second magnetic field gradient pulse, with polarity opposite that of the first gradient pulse. An encoding magnetic field gradient, constant from applying the first RF pulse until the end of applying the second RF pulse, is concurrently applied along the second direction. Following the encoding, a spin signal is measured concurrently with application of a constant readout magnetic field gradient.

The invention relates to a method of Dixon-type MR imaging. It is an object of the invention to provide an MR imaging technique using bipolar readout magnetic field gradients with an improved estimation of the main field inhomogeneity to eliminate residual artifacts. In accordance with the invention, a method of MR imaging of an object placed in a main magnetic field within an examination volume of a MR device is proposed, wherein the method comprises the steps of: subjecting the object (10) to an imaging sequence to generate at least two sets of echo signals at two or more different echo times using bipolar pairs of readout magnetic field gradients, one set of echo signals being generated at a first echo time (TE1) and the other set of echo signals being generated at a second echo time (TE2), acquiring the echo signals from the object (10), reconstructing a first image from the echo signals attributed to the first echo time (TE1) and a second image from the echo signals attributed to the second echo time (TE2), computing modified first and second images by compensating for a fat shift in the reconstructed first and second images respectively, estimating phase errors in the acquired echo signals on the basis of the first and second images and the modified first and second images using a signal model including the resonance spectra of fat and water and the spatial variation of the main magnetic field, andreconstructing a water image and/or a fat image by separating the signal contributions of fat and water to the acquired echo signals using the estimated phase errors. Moreover, the invention relates to a MR device (1) and to a computer program to be run on a MR device (1).

A method, an apparatus, and a device for magnetic resonance chemical shift encoding imaging are provided. The method includes in a phasor-error spectrum established based on a simplified multi-point magnetic resonance signal model, determining a pixel point having a unique phase factor value and causing the phasor-error spectrum to reach a local minimum value as an initial seed point; estimating a phase factor value of a pixel point to be estimated according to the initial seed point to obtain a field map; mapping and merging the field maps at the highest resolution to obtain a reconstructed field map; determining a reconstructed seed point from the reconstructed field map, and estimating the reconstructed seed point to obtain a phase factor value of a reconstructed pixel point to be estimated.

In a magnetic resonance measurement sequence, an inversion pulse is applied that acts on a longitudinal magnetization of a first spin species and a second spin species, for example on a water portion and a fat portion. An excitation pulse is applied after a predetermined time period. At least one manipulation pulse is subsequently applied, respectively with associated gradient pulse.

A method and apparatuses are provided to perform chemical species separation in magnetic resonance (MR) imaging (MRI). At least three MR images corresponding respectively to different echo times are obtained and represent signals from multiple chemical species including a first species and a second species in a tissue. A plurality of dual-echo pairs is selected from the at least three MR images. For each pair, a set of dual-echo separated images including a B0 field map, a first image for the first species, and a second image for the second species is estimated. An initial set of combined images including at least one of: an initial combined B0 field map, first, and second image is generated by combining at least one of: two or more of the B0 field maps, two or more of the first images, and two or more of the second images.

A method, an apparatus, and a device for magnetic resonance chemical shift encoding imaging are provided. The method includes in a phasor-error spectrum established based on a simplified multi-point magnetic resonance signal model, determining a pixel point having a unique phase factor value and causing the phasor-error spectrum to reach a local minimum value as an initial seed point; estimating a phase factor value of a pixel point to be estimated according to the initial seed point to obtain a field map; mapping and merging the field maps at the highest resolution to obtain a reconstructed field map; determining a reconstructed seed point from the reconstructed field map, and estimating the reconstructed seed point to obtain a phase factor value of a reconstructed pixel point to be estimated.

It is proposed a method for post-processing images of an region of interest in a subject, the images being acquired with a magnetic resonance imaging technique, the method for post-processing comprising at least the step of: unwrapping the phase of each image, extracting a complex signal over echo time for at least one pixel of the unwrapped images, and calculating fat characterization parameters by using a fitting technique applied on a model, the model being a function which associates to a plurality of parameters each extracted complex signal, the plurality of parameters comprising at least two fat characterization parameters, the magnitude error and the phase error generated by the use of the bipolar readout gradients, the fitting technique being a non-linear least-square fitting technique using pseudo-random initial conditions.