65 results about "Echo planar" patented technology

Mapping of myelin water content in white matter may provide important information for early diagnosis of multiple sclerosis and the detection of white matter abnormality in other diseases. It is disclosed here that free induction decay (FID) of each voxel at multiple slice locations is acquired in the brain using an echo-planar spectroscopic imaging (EPSI) pulse sequence. The multi-slice EPSI acquisition is designed to have a short first echo time (˜2 ms) and echo-spacing (˜1 ms) in order to acquire multiple sampling points during the fast decay of the myelin water signal. Multi-compartment analysis is then applied to the FID in each pixel using a 3-pool model of white matter to obtain quantitative maps of the myelin water fraction. Using this technique, the MR data for whole brain mapping of the myelin water can be acquired in less than 10 minutes, making this technique feasible for routine clinical applications.

When performing susceptibility-emphasized imaging using the echo planar method in an MRI apparatus, it is possible to obtain a susceptibility-emphasized image having a preferable signal-to-noise ratio.When measuring a plurality of echo signals by applying a phase blip gradient magnetic field to inverse the polar characteristic of the frequency encode gradient magnetic field, the echo signals are divided into a first echo signal group and a second echo signal group.Image data is acquired from the first echo signal group while mask data is acquired from the second echo signal group.A susceptibility-emphasized image is obtained from the image data and the mask data.

The invention discloses a circular synthetic aperture radar imaging method, belonging to the technical field of electronic signal processing. The invention relates to a spatial remote sensing and air-to-ground observation information processing technology, in particular to an onboard circular synthetic aperture radar imaging technology. According to the imaging method, an original oblique plane echo is mapped to the ground plane by solving the inverse of a system kernel function, and the distribution of signals in a wave number domain is obtained by multiplying an azimuth frequency domain with a reference function, so that plane wave approximation is avoided, the problem that the size of an imaging area of the traditional polar format algorithm is limited can be solved, and the imaging of a large imaging scene can be realized; pseudo-polar coordinates are used for replacing rectangular coordinates as an intermediate interpolation transition matrix, and the distribution density characteristic of the signals in the wave number domain is considered, so that the interpolation precision is higher, the obtained image resolution is higher, and the high resolution imaging can be realized; the imaging process only involves one-dimensional interpolation, and fast algorithms such as chirp z transform (CZT) and inverse fast Fourier transform (IFFT) are adopted, so that the method has very high computational efficiency and can realize rapid imaging.

An improved magnetic resonance imaging (MRI) methodology uses an abbreviated initial MRI sequence to generate sequence diagnostic parameters. The sequence diagnostic parameters have a fixed relationship to certain sequence-conditioning parameters, and are used for calculating characteristic values of the sequence-conditioning parameters. The read out gradient pulse sequence is modified in accordance with the calculated characteristic values of the sequence-conditioning parameters. The modified read out gradient pulse sequence is then incorporated into a subsequent MRI pulse sequence used for obtaining a diagnostic image. The methodology has particular application in so called ultra fast MRI process which include echo-planar imaging (EPI) and echo-volume imaging (EVI).

In a method and apparatus for echo planar magnetic resonance (MR) imaging sequence of phase encoding gradient fields and a sequence of readout gradient fields are applied in order to produce a well-defined zigzag-type trajectory for entering raw data into k-space. Zigzag-type trajectories can be achieved that have flanks without curvature, or without significant curvature. Cartesian methods for image reconstruction of parallel MR imaging are applied to echo planar MR imaging with such zigzag-type trajectories.

The invention discloses an echo planar imaging method, including: obtaining multiple echo planar imaging data of a scanned part and obtaining several reference echo signals that have not been subject to phase encoding; establishing a fitting model between the actual phase deviation of the reference echo signals and the readout direction position and establishing the Hoff space related to the parameters of the fitting model; based on the actual phase deviation of the reference echo signals and the readout direction position, determining the optimal parameter group in the Hoff space; according to fitting model and the optimal parameter group, correcting the echo planar imaging data; reconstructing the corrected echo planar imaging data and obtaining the magnetic resonance image of the scanned part. The echo planar imaging method of the invention can accurately correct the phases of an imaging signal. In addition, the invention also presents an echo planar imaging system.

Provided is a plane echo imaging method. The plane echo imaging method includes the follow steps: dividing a K space into a lot of subspaces; carrying out an under-sampling over the multiple subspaces and obtaining a K space data; reconstructing the K space data and obtaining a reconstructed image. The plane echo imaging method divides the K space into a lot of subspaces, and carried out the under-sampling over the multiple subspaces and obtains the K space data and finally reconstructs the K space data to obtain the reconstructed image. Due to the fact that compared with a full sampling, the sampling numbers are dramatically decreased, on the basis of guaranteeing the rapid imaging, the gradient switching rate and climbing gradient are reduced, and the vortex is prevented from influencing the image imaging quality by the distortion and other artifact influences. The plane echo imaging method and the system can reduce the sampling points, so that the plane echo imaging can not only guarantee the improvement of the image quality, but the calculation process and the reconstruction process are simple, convenient and feasible. The invention further provides the imaging system.

An echo planar imaging method comprises the following steps of: applying an echo planar imaging sequence, obtaining pre-scanning K space data after a pre-scanning progress, grouping the pre-scanning K space data to obtain odd number data line and even number data line K spaces, and respectively integrating the odd number data line and even number data line K spaces and carrying out the Fourier transformation to obtain an image domain data Iodd of odd number data lines and an image domain data Ieven of even number data lines; carrying out operation on the image domain data Iodd and Ieven, and obtaining a phase difference change rate [lambda] along a phase encoding direction; obtaining a phase difference scope [phi] of an imaging visual field FOV; obtaining offset data in the phase encoding directions of the K space odd number data lines and even number data lines, and carrying out phase encoding gradient compensation on the echo planar imaging sequence according to the offset data; carrying out formal scanning on the compensated echo planar imaging sequence, and obtaining imaging K space data; and carrying out the Fourier transformation to obtain an image. The invention further discloses a echo planar imaging device.

The invention discloses an inside-out echo-planar imaging method for shortening echo time. The method is characterized in that: a k-space trajectory extends to the outer side of a phase encoding direction from the center, wherein a gradient for generating the trajectory is composed of reading-out gradients which switch between forward and reverse directions and phase encoding gradients which switch between forward and reverse directions and gradually increases from zero. The method further comprises a step that: in order to accommodate the phase encoding gradients of which the area increases gradually without adding an echo spacing, the phase encoding gradient and a data collecting window are permitted to be overlapped. According to the method disclosed by the invention, an effective echo time in a sequence is located in the center of a first echo, the echo time is shortened greatly, and the signal to noise ratio is increased; since the contrast ratio of an image depends on signals of a k-space centre, and data of the k-space center are from an initial echo, T2 or T2* weighing of the obtained image is very small; and in diffusion imaging and arterial spin labeling imaging, the decreasing of the T2 or the T2* weighing is beneficial to improving the quality of the image.

A method for reduced field of view magnetic resonance (MR) imaging includes applying a pulse sequence using a plurality of gradient coils and at least one RF coil of a magnetic resonance imaging system. The pulse sequence includes a two dimensional (2D) echo-planar RF excitation pulse with a plurality of side lobes along a slice select axis and a multiband RF refocusing pulse. MR data is acquired in response to the application of the pulse sequence and at least one MR image is reconstructed based on the MR data. The at least one MR image may then be displayed.

Systems and methods for magnetic resonance imaging (“MRI”) that address the geometric distortions and blurring common to conventional echo planar imaging (“EPI”) sequences, and that provide new temporal signal evolution information across the EPI readout, are described. Echo planar time-resolved imaging (“EPTI”) schemes are described to implement an accelerated sampling of a hybrid space spanned by the phase encoding dimension and the temporal dimension. In general, each EPTI shot covers a segment of this hybrid space using a zigzag trajectory with an interleaved acceleration in the phase-encoding direction. The hybrid space may be undersampled and a tilted reconstruction kernel used to synthesize additional data samples.

A method and apparatus for B0 correction in echo-planar (EP) based magnetic resonance image (MRI) is disclosed. Two phase images are obtained from each of a first echo-planar imaging (EPI) acquisition and a second EPI acquisition. A first susceptibility map is generated based on the two phase images obtained from the first EPI acquisition and a second susceptibility map is generated based on the two phase images obtained from the second EPI acquisition. A smooth polynomial function for modeling the B0 drift and respiratory motion between the first EPI acquisition and the second EPI acquisition is initialized based on the first and second susceptibility maps. A compensated temperature map is then iteratively reconstructed based on the smooth polynomial function.

The invention provides an echo planar imaging sequence image reconstruction method comprising the following steps: acquiring echo planar imaging data Si and simultaneously acquiring three non-phase-encoded reference echo signals R1, R2 and R3; working out a parameter required for correcting the echo planar imaging data according to the reference echo signals; performing one-dimensional Fourier transform on the echo planar imaging data along a readout direction to obtain a transform result FSi, correcting FSi with the use of the correction parameter, and working out corrected echo planar imaging data; and performing one-dimensional Fourier transform on the corrected echo planar imaging data along a phase encoding direction to obtain an image. According to the echo planar imaging sequence image reconstruction method provided by the invention, in the presence of a stray field, the quick imaging advantage of echo planar sequence imaging can be kept, N / 2 artifacts can be effectively removed, and image deformation due to the existence of the stray field can be corrected.

In a method for an apparatus correcting image distortion in diffusion-weighted echo-planar magnetic resonance imaging, a marker sequence is applied before a diffusion-weighted echo planar imaging sequence, to form a combined sequence. The combined sequence is used to obtain marked images with different preset b values and different preset diffusion directions. The diffusion-weighted echo planar imaging sequence is used to obtain diffusion-weighted echo planar images with the same b values and diffusion directions as the marked images. A stretching coefficient and a displacement coefficient are calculated for each image data column of the diffusion-weighted echo planar image. The stretching coefficient and displacement coefficient are used to correct the diffusion-weighted echo planar images.

The invention provides a neural network based planar echo imaging method and device. The method comprises that according to a selected magnetic resonance parameter, a planar echo imaging sequence is used to scan a detected body, and k-space data is obtained; according to the k-space data, an initial magnetic resonance image of the detected body is obtained; and the initial magnetic resonance imageis input to pre-trained first and second neutral networks to obtain a final magnetic resonance image of the detected body. The first neural network is configured to eliminate a chemical displacementartifact, and the second neural network is configured to correct image deformation. Based on the neural network based planar echo imaging method and device, the chemical displacement artifact can be eliminated effectively while deformation can be corrected, and the quality of the magnetic resonance image obtained by reconstruction is higher.

The invention discloses a chemical shift imaging method and system. The method comprises the following steps: a) applying a magnetic field to a region of interest according to an imaging sequence, the imaging sequence comprising a plurality of radio-frequency pulses and a plurality of gradient pulses, wherein the radio-frequency pulses are excited continuously in sequence, and the gradient pulses comprise layer-selection gradient pulses and convergence gradient pulses, the last layer-selection gradient pulse being applied with one phase convergence gradient pulse, and the polarities of adjacent gradient pulses being opposite; b) collecting echo data through a series of gradient pulses with alternatively-opposite polarities by adopting a data reading mode of EPI; and c)carrying out data reconstruction to obtain a chemical shift image based on the echo data. Compared with a conventional chemical shift imaging CSI, according to the chemical shift imaging method and system in the technical scheme of the invention, the collection time is reduced to one order of magnitude, thereby helping to finish spectrum collection is a short time; and compared with echo planar spectrum imaging EPSI, 3-4 times of volume elements are collected under the same time and conditions.

The invention relates to a magnetic resonance imaging method and a magnetic resonance imaging system aiming at small targets. The magnetic resonance imaging method comprises the steps of: positioning a small-target region; exerting plane echo dispersion weighted imaging sequences in the small-target region; collecting signals released through the excitation of the plane echo dispersion weighted imaging sequences, and obtaining K space data according to the signals; and carrying out Fourier transform on the K space data to obtain small target images. The small-target region positioning comprises the steps of: exerting fast small-angle excitation sequences, and obtaining three positioning images of the cross section, the sagittal plane and the coronal plane; and obtaining secondary positioning images aiming at the small-target region according to the three positioning images of the cross section, the sagittal plane and the coronal plane, and carrying out positioning. The plane echo dispersion weighted imaging sequence exertion step comprises the process that: the plane echo dispersion weighted imaging sequences formed through the combination of selective excitation of the two-dimensional space is excited for many times. Through positioning the small-target region and exerting the plane echo dispersion weighted imaging sequences on the small-target region, the goal of carrying out magnetic resonance imaging on the small-target region is reached.

In a method for an apparatus correcting image distortion in diffusion-weighted echo-planar magnetic resonance imaging, a marker sequence is applied before a diffusion-weighted echo planar imaging sequence, to form a combined sequence. The combined sequence is used to obtain marked images with different preset b values and different preset diffusion directions. The diffusion-weighted echo planar imaging sequence is used to obtain diffusion-weighted echo planar images with the same b values and diffusion directions as the marked images. A stretching coefficient and a displacement coefficient are calculated for each image data column of the diffusion-weighted echo planar image. The stretching coefficient and displacement coefficient are used to correct the diffusion-weighted echo planar images.

A method for reduced field of view magnetic resonance (MR) imaging includes applying a pulse sequence using a plurality of gradient coils and at least one RF coil of a magnetic resonance imaging system. The pulse sequence includes a two dimensional (2D) echo-planar RF excitation pulse with a plurality of side lobes along a slice select axis and a multiband RF refocusing pulse. MR data is acquired in response to the application of the pulse sequence and at least one MR image is reconstructed based on the MR data. The at least one MR image may then be displayed.

In a method and apparatus for echo planar magnetic resonance (MR) imaging sequence of phase encoding gradient fields and a sequence of readout gradient fields are applied in order to produce a well-defined zigzag-type trajectory for entering raw data into k-space. Zigzag-type trajectories can be achieved that have flanks without curvature, or without significant curvature. Cartesian methods for image reconstruction of parallel MR imaging are applied to echo planar MR imaging with such zigzag-type trajectories.

The invention discloses a 3D gradient spin echo imaging method and device for oscillation gradient preparation. The imaging method comprises the following steps: firstly, destroying previous residualtransverse magnetization in a global saturation module; secondly, embedding a pair of trapezoidal cosine oscillation gradients into a 90 degrees <x>- 180 degrees <y>- 90 degrees <-x> radio frequency pulse through a diffusion coding module, and separating diffusion coding from signal acquisition; then, using a fat saturation module\ for inhibiting the fat signal; and finally, acquiring signals in agradient spin echo reading mode, and using multiplexing sensitivity coding for reconstructing and correcting phase errors among multiple excitations. Compared with an oscillation gradient dispersionsequence based on 2D plane echo used on a 3T clinical system, the gradient spin echo sequence prepared by 3D oscillation gradient effectively improves the imaging time and the signal to noise ratio, and is beneficial to clinical conversion of a time-dependent dispersion MRI technology.

The invention discloses a high-resolution high-signal-to-noise-ratio deformation-free single excitation plane echo imaging method and device based on deep learning, and the method comprises the steps:obtaining a first image and a related auxiliary image of a single excitation plane echo, and obtaining a second image which is collected in a mode of multiple excitation and meets a preset condition;performing deep neural network training according to the first image, the related auxiliary image and the second image to obtain a network weight parameter so as to generate a deep neural network; and receiving a third image and a related auxiliary image of the single excitation plane echo, and inputting the third image and the related auxiliary image into the deep neural network to generate an imaging result. According to the method, the high-resolution and high-signal-to-noise-ratio non-deformation magnetic resonance image can be obtained under rapid scanning of single excitation, and the problems that in an existing single excitation EPI technology, the signal-to-noise ratio and deformation artifacts are serious, and the resolution ratio is low are effectively solved, and the problem that the collection time is too long when a multi-excitation technology is used is effectively solved.

The invention belongs to the technical field of magnetic resonance imaging, and particularly relates to a multiple-shot plane echo magnetic resonance imaging method based on a deep learning neural network. The invention provides a brand-new method for accurate phase correction and rapid image reconstruction for multiple-shot plane echo magnetic resonance imaging. Compared with a traditional under-sampling image reconstruction algorithm based on a model, the deep learning neural network is utilized, deep learning is applied to aliasing correction of multiple shot echo planar imaging (MSH-EPI) images, and an aliasing-free single shot echo planar imaging (SSH-EPI) image is used as a target in the training stage. An aliasing SSH-EPI image having the same under-sampling factor and trajectory as the multiple shot plane echo is sent to the network so as to improve the precision of phase estimation.

A system and method for accelerated MR imaging includes a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet, and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly comprising at least one RF transmit coil and comprising multiple coils to acquire MR images. The MRI apparatus also has a computer programmed to excite multiple pencil regions by use of an under-sampled echo-planar excitation trajectory and acquire MR signals simultaneously on multiple channels of the RF coil assembly. The computer is also programmed to separate contributions from the various multiple pencil regions by use of parallel imaging reconstruction.

Images are reconstructed from k-space data using a model-based image reconstruction that prospectively and simultaneously accounts for multiple non-idealities in accelerated single-shot-EPI acquisitions. In some implementations, nonlinear regularization (e.g., sparsity regularization) is also incorporated to mitigate noise amplification. The reconstructed images have reduced distortions and noise amplification effects relative to those images that are processed using conventional post-reconstruction techniques to correct for non-idealities.

A system and method for accelerated MR imaging includes a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet, and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly comprising at least one RF transmit coil and comprising multiple coils to acquire MR images. The MRI apparatus also has a computer programmed to excite multiple pencil regions by use of an under-sampled echo-planar excitation trajectory and acquire MR signals simultaneously on multiple channels of the RF coil assembly. The computer is also programmed to separate contributions from the various multiple pencil regions by use of parallel imaging reconstruction.

In a method for an apparatus correcting image distortion in diffusion-weighted echo-planar magnetic resonance imaging, a marker sequence is applied before a diffusion-weighted echo planar imaging sequence, to form a combined sequence. The combined sequence is used to obtain marked images with different preset b values and different preset diffusion directions. The diffusion-weighted echo planar imaging sequence is used to obtain diffusion-weighted echo planar images with the same b values and diffusion directions as the marked images. A stretching coefficient and a displacement coefficient are calculated for each image data column of the diffusion-weighted echo planar image. The stretching coefficient and displacement coefficient are used to correct the diffusion-weighted echo planar images.

The invention discloses a prospective phase correction planar echo imaging technology, which comprises a planar echo imaging phase encoding error measurement sequence, a phase encoding error calculation method, a phase encoding error compensation sequence and a phase encoding error compensation method in planar echo imaging. A phase encoding error is measured and calculated through a reference scanning sequence, and then a compensation gradient is added to phase encoding in a scanning sequence of planar echo imaging to compensate the influence of B0 field heterogeneity, an eddy current field,gradient channel asymmetry and the like, so that artifacts can be reduced, and the signal-to-noise ratio can be increased.

The invention discloses a method for correcting planar echo two-dimensional spatial selective pulses. The method comprises the steps of: increasing a delay compensation amount between a gradient channel and a radio frequency channel of a two-dimensional spatial selective excitation pulse, and moving the position of excitation K space, so as to enable the centers of the excitation K spaces in odd and even rows to be aligned. For the two-dimensional spatial selective pulse adopting the planar echo to excite the K space track, the method can ensure that the centers of the K spaces excited by theodd and even sub SINC waveforms are aligned, and can greatly improve the two-dimensional excitation contour, thereby improving the image quality of small-view imaging.