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.

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, and —reconstructing 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).

In a method and magnetic resonance (MR) apparatus for acquiring MR data from a volume of an object in which first and second excitable spin types are present that differ in their Larmor frequencies by a chemical shift, an MR sequence with at least one radio-frequency pulse sequence selectively excites the first spin type or selectively suppresses MR signals of the second spin type. A B0 map describing the basic field distribution in a region of interest of the volume is established. First and second items of distribution information, which respectively describe the spectral distribution of Larmor frequencies of the first and second spin types, are derived from the B0 map. A pulse sequence parameter that describes the excitation spectrum of the radio-frequency pulse sequence is optimized based on the items of distribution information, with regard to a quality criterion that optimizes selective excitation and/or suppression.

A method of Dixon-type MR imaging includes subjecting the object (10) to a first imaging sequence (31) including a series of refocusing RF pulses. A single echo signal is generated in the time interval between two consecutive refocusing RF pulses. The first echo signals from the object (10) are acquired at a first receive bandwidth using unipolar readout magnetic field gradients. The object (10) is further subject to a second imaging sequence (32), which includes a series of refocusing RF pulses. A pair of second echo signals is generated in each time interval between two consecutive refocusing RF pulses. The pairs of second echo signals from the object (10) are acquired at a second receive bandwidth using bipolar readout magnetic field gradients. The second receive bandwidth is higher than the first receive bandwidth. Signal contributions from water protons and fat protons are separated and an MR image is reconstructed.

A bridge member containing MR responsive material is provided in an open space between body parts to establish a correspondence between the body parts. The MR responsive material generates magnetic resonance signals in response the RF excitation, so that between the separate body parts via the bridge member magnetic resonance signal are obtained from positions between which there is at most a limited spatial variation of the main magnetic field, so that phase ambiguities between the signals from these positions are avoided. Thus, chemical shift separation, notably water-fat separation though a region-of-interest containing several (both) body parts may rely on a smoothness condition imposed on the spatial distribution of the main magnetic field. This avoids artefacts, such as water-fat swaps when separating water and fat contributions in the reconstructed magnetic resonance image.

The invention relates to a method of MR imaging of an object. It is an object of the invention to provide a multi-gradient echo imaging technique with increased acquisition speed and intrinsic suppression of artefacts from Bo inhomogeneities, T.sub.2* decay, chemical shift, motion, and/or flow, in particular in combination with radial or spiral k-space trajectories. The method of the invention comprises the steps of: —subjecting the object (10) to an imaging sequence comprising RF excitation pulses and switched magnetic field gradients, wherein multiple echo signals are generated at different echo times after each RF excitation pulse, —acquiring the echo signal data along radial or spiral k-space trajectories, wherefore the imaging sequence comprises magnetic field gradient blips in the x-/y- and/or z-directions; —separating signal contributions from water and fat to the echo signals and estimating a B.sub.0 map and/or an apparent transverse relaxation time map (T.sub.2* map) using a Dixon algorithm; and —synthesizing an image of a specified contrast from the echo signal data, the Bo map and/or the T.sub.2* map. Moreover, the invention relates to a MR device (1) and to a computer program for a MR device (1).

Exemplary quantitative susceptibility mapping methods, systems and computer-accessible medium can be provided to generate images of tissue magnetism property from complex magnetic resonance imaging data using the Bayesian inference approach, which minimizes a cost function consisting of a data fidelity term and two regularization terms. The data fidelity term is constructed directly from the complex magnetic resonance imaging data. The first prior is constructed from matching structures or information content in known morphology. The second prior is constructed from a region having an approximately homogenous and known susceptibility value and a characteristic feature on anatomic images. The quantitative susceptibility map can be determined by minimizing the cost function. Thus, according to the exemplary embodiment, system, method and computer-accessible medium can be provided for determining magnetic susceptibility information associated with at least one structure.

Systems and methods for ZTE MRI are disclosed. An exemplary method includes obtaining Larmor frequencies of water and/or fat for a region of interest of a subject to be imaged at a pre-scan and setting a center frequency for an RF transceiver of the MR system at a value between the Larmor frequencies of water and fat. A ZTE pulse sequence is applied to the subject and MR signals in response to the ZTE pulse sequence are received from the subject. The received MR signals are demodulated with the center frequency and an in-phase ZTE image is generated from the demodulated MR signals.

Systems and methods for ZTE MRI are disclosed. An exemplary method includes obtaining Larmor frequencies of water and/or fat for a region of interest of a subject to be imaged at a pre-scan and setting a center frequency for an RF transceiver of the MR system at a value between the Larmor frequencies of water and fat. A ZTE pulse sequence is applied to the subject and MR signals in response to the ZTE pulse sequence are received from the subject. The received MR signals are demodulated with the center frequency and an in-phase ZTE image is generated from the demodulated MR signals.

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.