G01R33/56527

System and method for magnetic resonance imaging reconstruction using novel k-space sampling sequences

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.

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
20190195974 · 2019-06-27 ·

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.

Medical imaging apparatus having multiple subsystems, and operating method therefor

In a method for operating a medical imaging examination apparatus having multiple subsystems controlled by a control computer in a scan sequence, a control protocol for the scan is provided to the control computer, which determines sequence control data for the control protocol that define different functional subsequences of the scan, with different effective volumes assigned to each functional subsequence. Current ambient conditions of the apparatus are determined that are decisive for the determined relevant sequence control data and associated effective volumes. Control signals for the scan are determined from the sequence control data, the effective volumes and the current ambient conditions determined that optimize the functional subsequences of the scan.

CHEMICAL-SHIFT-SELECTIVE PHASE-COMPENSATED ADIABATIC 2-REFOCUSING PULSE PAIR AND SPECTRAL EDITING METHODS FOR ULTRA-HIGH-FIELD MAGNETIC RESONANCE SPECTROSCOPY
20240241199 · 2024-07-18 ·

A method for generating 2?-refocusing pulses for magnetic resonance spectroscopy (MRS), and for performing spectral editing of MRS data using differential custom bandpass editing. Acquisition may be performed using echo-planar spectroscopic imaging (EPSI), for example. The 2?-refocusing is achieved using chemical-shift-selective adiabatic 2?-refocusing pulses, without spatial-selective (e.g. slice-selective) refocusing. The spectral editing method uses two data sets with different bandpass (full and partial) editing spectra, and takes the difference of the two edited spectra. The approach lends itself to 3D spectroscopy at B.sub.0 of 7 T or higher, and permits whole brain J-coupled metabolite editing (e.g. 2HG or GABA), with greatly reduced specific absorption rate, shorter repetition time, minimal chemical-shift displacement artefacts (CDSAs), robustness to B.sub.0-inhomogeneity and indifference to B.sub.1.sup.+-inhomogeneity compared with existing spatial-selective methods, such as MEGA.

Method for the reduction of interference signals

The disclosure relates to techniques for acquiring measured data that has been recorded simultaneously via a magnetic resonance facility from at least two slices from an examination object comprising at least two different spin types. The techniques includes selecting a desired simultaneous recording of measured data from at least two slices in which during recording phases that generate field of view shifts have been imprinted, selecting a compensation factor to compensate for interference signals caused by the different spin types, determining a compensation phase for the phases to be imprinted in the desired recording as a function of the compensation factor, and carrying out the desired recording of measured data and/or reconstruction of image data from the measured data by applying the compensation phase that has been determined to the respective phases to be imprinted.

SYSTEM AND METHOD FOR AMPLITUDE REDUCTION IN RF PULSE DESIGN

A system and method for modifying RF pulse generated by an MRI system are provided. The method may include: obtaining an excitation variable-rate selective excitation (VERSE) factor and a refocusing VERSE factor; determining a first slice-selection gradient waveform based on an excitation factor and a reference excitation slice-selection gradient waveform; determining a second slice-selection gradient waveform based on a refocusing factor and a reference refocusing slice-selection gradient waveformslice-selection gradient waveformslice-selection gradient waveform; determining an excitation pulse based on the first slice-selection gradient waveform; determining a refocusing pulse based on the second slice-selection gradient waveform, wherein a ratio of the decimal part of the excitation factor to the decimal part of the refocusing factor is equal to a ratio of the amplitude of the first reference waveform to the amplitude of the reference refocusing slice-selection gradient waveform.

MAGNETIC RESONANCE CHEMICAL-SHIFT-ENCODED IMAGING METHOD, APPARATUS AND DEVICE

Provided are a magnetic resonance chemical-shift-encoded imaging method, apparatus, and device, belonging to the technical field of magnetic resonance imaging. The method comprises: in a phasor-error plot established on the basis of a two-point magnetic resonance signal model, determining to be an initial seed point a pixel having a unique phasor and causing said plot to reach a minimal local value; according to the initial seed point, estimating the phasor value of a to-be-estimated pixel to obtain a field map; mapping and merging the field map 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 the phasor value of the reconstructed to-be-estimated pixel; according to the reconstructed seed point and the phasor value of the reconstructed to-be-estimated pixel, obtaining two separate images having predetermined components. In the method, a region simultaneously containing two components is identified as a seed point, eliminating the deviation caused by phasor-value jump at high resolution and ensuring the correctness of the seed point ultimately selected.

Propeller with Dixon water fat separation
10175331 · 2019-01-08 · ·

The invention relates to a magnetic resonance imaging system (100) for acquiring at least one set of k-space blade data from an imaging zone of a subject (118), wherein the magnetic resonance imaging system (100) comprises a memory (138) for storing machine executable instructions and a processor (130) for controlling the magnetic resonance imaging system (100), wherein execution of the machine executable instructions causes the processor (130) to perform for each blade of the at least one set of k-space blade data: control the MRI system (100) to acquire at least one k-space blade data using at least one echo time for purposes of performing a Dixon technique, wherein k-space blade data are acquired in accordance with a blade shape; reconstruct at least one blade image data using the at least one k-space blade data; generate water blade image data and fat blade image data using the at least one blade image data; and transform the water and fat blade image data to water and fat k-space blade data respectively and perform PROPELLER reconstruction of the water and fat k-space blade data.

Dixon MR imaging with suppression of flow artifacts
10175330 · 2019-01-08 · ·

The invention relates to a method of MR imaging of a body (10) of a patient. It is an object of the invention to provide a method that enables efficient compensation of flow artifacts, especially for MR angiography in combination with Dixon water/fat separation. The method of the invention comprises the steps of: a) generating MR echo signals at two or more echo times by subjecting the portion of the body (10) to a MR imaging sequence of RF pulses and switched magnetic field gradients, wherein the MR imaging sequence is a Dixon sequence; b) acquiring the MR echo signals; c) reconstructing one or more single-echo MR images from the MR echo signals; d) segmenting the blood vessels from the MR images; e) detecting and compensating for blood flow-induced variations of the amplitude or phase in the single-echo MR images within the blood vessel lumen, and f) separating signal contributions from water and fat spins to the compensated single-echo MR images. Moreover, the invention relates to a MR device (1) and to a computer program for a MR device (1).

Method and magnetic resonance apparatus for reconstructing an MR image dependent on the chemical shift

In a method and magnetic resonance apparatus for reconstructing an MR image of a volume segment within an examination object, MR data within the volume segment are acquired according to a separation method by MR data for a k-space line being acquired respectively in steps while a readout gradient is activated in the same readout direction. An image of a first substance and an image of a second substance are thereby reconstructed. A shift length, by which the image of the first substance and the image of the second substance are displaced relative to one another due to the chemical shift in the readout direction is determined. The image of the first substance and/or the image of the second substance is shifted as a function of the shift length, to compensate for the relative displacement between the images of the first and second substances in the readout direction due to the chemical shift. An MR image is generated by combining the images of the first and second substances.