62 results about "Gradient echo" patented technology

The invention discloses a deep learning algorithm-based spinal MRI precise synthesis CT image processing system and method for central axis type spinal arthritis, and the system comprises a data obtaining unit which is used for obtaining a three-dimensional T1 weighted multi-gradient echo sequence, a T2 weighted sequence and a water-fat separation sequence which are obtained through the magnetic resonance imaging of the spinal column of a target user; the spatial registration unit is used for inputting the multi-sequence data into a deformable registration network so as to carry out spatial registration on the multi-modal features; the feature processing unit is used for carrying out feature fusion on the registered multi-modal features and carrying out double-domain splitting based on an anatomical attention gating mechanism to obtain skeleton features and soft tissue features; and the image fusion unit is used for synthesizing a synthesized CT image with an HU value corresponding to the spine of the target user based on the skeleton features and the soft tissue features, so that radiation-free high-precision CT image acquisition is realized, the diagnosis grading requirement on the axis type spine joint in the spine can be met, and the influence of radiation on the target user can be reduced.

The invention provides a brain low-frequency conductivity tensor modeling method, a brain low-frequency conductivity tensor modeling system, a medium and electronic equipment. The method comprises the following steps: acquiring a phase image of a fast spin echo sequence of a brain; acquiring a high-frequency conductivity image of the brain based on the phase image; collecting a diffusion weighted amplitude image of the brain based on a multi-excitation diffusion weighted sequence; based on the diffusion weighted amplitude image, using a multi-interlayer model to obtain diffusion microstructure parameters of the brain; generating a low-frequency conductivity tensor image of the brain based on the high-frequency conductivity image and the diffusion microstructure parameters; generating a digital head model based on the brain magnetization preparation fast gradient echo sequence; and generating a craniocerebral low-frequency conductivity tensor model based on the low-frequency conductivity tensor image and the digital head model. According to the brain low-frequency conductivity tensor modeling method and system, the medium and the electronic equipment, more accurate target point planning is provided for the tTIS.

The invention discloses a quantitative magnetic susceptibility imaging accelerated scanning method based on short gradient echoes, and belongs to the field of medical image scanning, and the method comprises the steps: designing scanning parameters suitable for short echo data; constructing a de-noising diffusion probability model comprising a forward noise adding process and a reverse de-noising process, wherein a wavelet transform module is embedded in the reverse de-noising process; extracting short echo data from full echo data of the multi-gradient echo sequence, and training the de-noising diffusion probability model based on the short echo data to obtain a trained de-noising diffusion probability model; configuring the scanning parameters in a magnetic resonance imaging system; acquiring short echo quantitative magnetic susceptibility imaging data based on the configured scanning parameters; and inputting the acquired short echo quantitative magnetic susceptibility imaging data into the trained denoising diffusion probability model, and reconstructing a quantitative magnetic susceptibility image. According to the method, through scanning parameter setting and deep learning model optimization reconstruction, the existing quantitative magnetic susceptibility reconstruction scanning time can be greatly reduced, and the image quality is kept consistent.

The embodiment of the invention provides a magnetic resonance imaging method and related equipment. The magnetic resonance imaging method comprises the following steps: applying a multi-spin echo sequence in each magnetization reset period, and collecting a group of multi-spin echo data sets until M groups of multi-spin echo data sets are obtained; after each magnetization reset period, a T1rho preparation pulse with spin locking duration is applied, then a multi-gradient echo sequence is applied, a group of multi-gradient echo data sets are collected until M groups of multi-gradient echo data sets are obtained, and the M groups of multi-spin echo data sets and the M groups of multi-gradient echo data sets correspond to M different spin locking durations respectively; and performing fitting operation on the M groups of multi-spin echo data sets and the M groups of multi-gradient echo data sets to generate a quantitative atlas. According to the technical scheme, the problems that a traditional T1rho sequence is long in scanning time, low in signal-to-noise ratio and single in contrast ratio are effectively solved, and the technical effects of time multiplexing and multi-contrast imaging are achieved.

The invention discloses a magnetic resonance 3DTOF angiography method based on variable echo time. The method comprises the following steps: step 1, respectively applying a magnetization transmission pulse and a saturation pulse to an imaging area; step 2, calculating the coding gradient lobe area of the imaging region to obtain the time of flow compensation, and determining the specific change condition of the echo time of the imaging region; 3, adopting a 3DTOF gradient echo sequence to obtain a final scanning sequence time sequence, and scanning to obtain magnetic resonance angiography data; and S4, performing filtering processing on the obtained magnetic resonance angiography data, performing reconstruction, generating a DICOM image, performing MIP three-dimensional reconstruction, and finally obtaining a three-dimensional image of the blood vessel. A variable echo time method is adopted, the closer to the center of a k space, the shorter the echo time is, the fewer signal errors are caused by blood flow, meanwhile, more sufficient time is provided for gradient compensation, artifacts caused by blood flow are reduced, and a higher-quality magnetic resonance blood vessel image is obtained.

The present invention relates to the field of magnetic resonance imaging, and particularly to a method and system for magnetic resonance imaging. The method includes: acquiring a spin echo sequence and a plurality of gradient echo sequences; performing fitting calculations based on the plurality of gradient echo sequences to obtain a fitting density quantitative map, a fitting longitudinal relaxation quantitative map, and a fitting quasi-transverse relaxation quantitative map; obtaining a gradient-weighted image based on the fitting density quantitative map, the fitting longitudinal relaxation quantitative map, and the fitting quasi-transverse relaxation quantitative map; obtaining a relaxation decay image based on the gradient-weighted image and the spin echo sequence; obtaining a transverse relaxation quantitative map based on the relaxation decay image; performing weighted summation based on the fitting density quantitative map, the fitting longitudinal relaxation quantitative map, the relaxation decay image, and the transverse relaxation quantitative map to obtain a magnetic resonance multi-parameter image. The present invention increases the types of multi-parameter maps, facilitating the rapid acquisition of multiple contrast images.

This invention provides a method for correcting the localization errors caused by field inhomogeneity and obtaining position information of a wireless marker in an MRI scanner. In one embodiment, said method comprises the steps of: a) Providing said wireless marker in said workspace; b) Performing a pulse sequence with said MRI scanner, comprising: i) Exciting all spins inside said workspace; ii) Applying a pre-phasing gradient along a frequency encoding; iii) Applying dephasing gradients in two directions orthogonal to said frequency encoding direction; and iv) Applying two readout gradients with same amplitude and opposite polarities along said frequency encoding direction to form a first and a second gradient echo; c) Acquiring a first and a second MR signal using an array of RF receiver coils by sampling said first and second gradient echoes respectively; and d) Reconstructing tracking signals from said first and second MR signals and calculating said position information.

Embodiments of the present disclosure provide a method, a system and a medium for magnetic resonance imaging (MRI), the method comprising: applying a gradient echo sequence to an object and performing a dummy scan on the object until a steady-state of the gradient echo sequence is reached; continuing the dummy scan and maintaining the steady-state of the gradient echo sequence; and in response to receiving a trigger signal while the gradient echo sequence is in the steady-state, acquiring a gradient echo magnetic resonance signal of the object. The system includes at least one processor; the at least one processor is configured to cause the system to perform the method for MRI.

The application carries out quantitative susceptibility mapping (QSM) reconstruction on original gradient echo data (GRE), then constructs an individual space standardization QSM brain template by using structural images, carries out linear and nonlinear registration processing on QSM images of all subjects and the brain template, so as to achieve the purpose of standardization processing of the QSM images; meanwhile, the structural images are automatically segmented, the gray matter and white matter masks obtained after segmentation are used to carry out matrix point multiplication on the QSM images, then the standardized QSM images are smoothed and corresponding smoothing compensation is carried out; in FSL, a general linear model is constructed, and voxel-level whole brain statistical analysis is carried out on the QSM images; the masks obtained after automatic nucleus segmentation are used to extract the susceptibility values of corresponding deep nuclei in the QSM images; the whole process does not need to manually draw the interested region, and the quantitative analysis of the susceptibility values based on voxels and based on the interested region can be automatically completed, and the repeatability, comparability and reliability are greatly improved.

The present invention provides a method, system, medium, and electronic device for modeling a low-frequency conductivity tensor of the brain. The method includes the following steps: acquiring a phase image of a fast spin echo sequence of the brain; acquiring a high-frequency conductivity image of the brain based on the phase image; acquiring a diffusion-weighted amplitude image of the brain based on a multi-excitation diffusion-weighted sequence; acquiring diffusion microstructure parameters of the brain using a multi-layer model based on the diffusion-weighted amplitude image; generating a low-frequency conductivity tensor image of the brain based on the high-frequency conductivity image and the diffusion microstructure parameters; generating a digital skull model based on a magnetization-prepared fast gradient echo sequence of the brain; and generating a low-frequency conductivity tensor model of the brain based on the low-frequency conductivity tensor image and the digital skull model. The method, system, medium, and electronic device for modeling a low-frequency conductivity tensor of the brain of the present invention provide more accurate target planning for tTIS.

The present invention provides a method and device for adaptive sampling of magnetic resonance signals based on deep learning, comprising: determining a sampling space, a sampling value threshold, and the number of sampling points for a single excitation; selecting an initial region to be sampled based on the number of sampling points; determining a 3D epi-intensity spectroscopy (EPI) sequence corresponding to a single excitation based on phase encoding of the sampling points within the region to be sampled; performing a single radiofrequency excitation based on the 3D EPI sequence to obtain a corresponding gradient echo signal; reconstructing an optimized dMRI image based on the gradient echo signal; inputting the optimized dMRI image into a trained full-sampling dMRI image prediction model to predict a full-sampling dMRI image and obtain a reconstructed image error map; obtaining a sampling value for each sampling point in the sampling space based on the reconstructed image error map; and determining a region to be sampled for the next sampling based on the sampling value of each sampling point and the sampling value threshold. This application further shortens scanning time and improves the accuracy of the generated dMRI images.

The invention is suitable for the technical field of magnetic resonance chemical exchange saturation transfer imaging, and provides a magnetic resonance chemical exchange saturation transfer imaging method, device, equipment, product and storage medium. A gradient echo sequence is adopted to collect saturated water molecule signals, and the collected water molecule signals are stored in a K space; and wave control coding is introduced in the acquisition process, and a CEST image is reconstructed based on a water molecule signal of a K space. The introduction of wave control coding can reduce the scanning time. Due to the fact that the wave control coding sampling efficiency is high, a larger matrix size can be supported within the same time, high-resolution imaging is achieved, the partial volume effect can be relieved, and CEST quantitative accuracy is improved.

A method according to the invention for acquiring T2*-weighted measurement data of a test object using a magnetic resonance system comprises the steps: - irradiating a first RF excitation pulse to excite spins in a first layer in the test object, - switching gradients to generate at least one gradient echo signal, - after an echo time following the irradiation of the first RF excitation pulse, acquiring a first gradient echo signal from the first layer, - after the irradiation of the first RF excitation pulse and before the elapsed echo time following the first RF excitation pulse, irradiating at least one further RF excitation pulse to excite spins in a further layer,wherein, before the application of a further RF excitation pulse and after each RF excitation pulse preceding the further RF excitation pulse, a pre-rephasing gradient of a moment corresponding to the further RF excitation pulse following the pre-rephasing gradient is switched, - recording generated further gradient echo signals from further layers. By switching the pre-rephasing gradients according to the invention, gradient echo signals of the spins of different layers excited by the first RF excitation pulse and the at least one further RF excitation pulse can be separated. Thus, the echo time TE, which elapses until a first gradient echo signal is measured after the first RF excitation pulse, can be used to generate and measure further gradient echo signals in further layers after the first gradient echo signal, which increases the readout efficiency.

This application discloses a magnetic resonance chemical exchange saturation transfer imaging method, system, device, and storage medium. The method includes: applying a radio frequency saturation pulse for a first preset time to a region to be detected; applying a radio frequency echo pulse to the region to be detected and acquiring several gradient echo signals generated after activation by the radio frequency echo pulse; and using radial sampling to read the gradient echo signals along a preset direction to generate a magnetic resonance image. Through this method, this application effectively shortens the signal acquisition time by using gradient echo readings, effectively suppresses motion artifacts by using radial acquisition, and applies post-processing methods such as fitting to the acquired chemical exchange saturation transfer imaging spectral data to achieve water-lipid signal separation and extract and analyze the target signal.

A method for generating an image of a subject with a magnetic resonance imaging (MRI) system includes receiving MR image data acquired with the MRI system, wherein the MR image data comprises first gradient echo data and second gradient echo data and determining a linear phase error estimate. The linear phase error estimate may be based on all of the MR image data or a subvolume thereof, and may include calculating a pixel phase error for each of a plurality of pixels within the MR image data and determining a mean of the pixel phase error. Corrected MR image data is generated based on the linear phase error estimate, and then a water image and / or a fat image based on the corrected MR image data.

The invention discloses a complete-cycle lung function magnetic resonance imaging method which comprises the following steps: in a free breathing state of a subject, acquiring lung coronal magnetic resonance images at different time points at the same anatomical position by using a gradient echo sequence, and selecting a lung aorta region R1 and a region R2 containing lung parenchyma and liver tissue; after the average signal time sequences of the R1 and the R2 are respectively subjected to high-pass filtering to remove the influence of respiration and low-pass filtering to remove the influence of heart blood flow, fitting is carried out in a cosine function form to obtain the phase of the signal, and the average signal time sequences in the R1 and the R2 are respectively reordered as RS1 and RS2 in a heart cycle and a respiration cycle according to the sizes of phase values. According to the method, the lung image is subjected to segmentation and registration and then is reordered according to RS1 and RS2, respiration and heart cycle parameters of each local area of the lung image are calculated, lung ventilation, lung perfusion, ventilation peak reaching time and perfusion peak reaching time images are generated, the local function of the lung can be non-invasively evaluated, and the method has very high clinical value.

The application provides a denoising method and device of an image, electronic equipment and medium. The method acquires myelin water image data of human brain tissue based on a preset multi-echo gradient echo sequence, and calculates amplitude image data acquired at each echo time point; determines a first noise level metric value of the multi-echo gradient echo sequence based on a noise value in the amplitude image data acquired at the last echo time point and an amplitude of the amplitude image data corresponding to the first echo time point; and obtains a corresponding second noise level metric value based on an error value between the first noise level metric value and the second noise level metric value. The amplitude image data at each echo time point is subjected to a preset denoising convolutional neural network to obtain a noise value of the amplitude image data at each echo time point, thereby denoising the amplitude image data acquired at the corresponding echo time point, obtaining noise-free amplitude image data at each echo time point, and improving the denoising effect.

Disclosed herein is a medical system (100) comprising a magnetic resonance imaging system (102). The execution of the machine executable instructions (140) causes a computational system (132) to: control (200) the magnetic resonance imaging system with multi-echo gradient echo pulse sequence commands to acquire the k-space data (144), form (202) a first k-space data group (146) by aggregating a first selected k-space data portion, form (204) a second k-space data group (148) by aggregating a second selected k-space data portion, form (206) at least one additional k-space data group (150) by aggregating an additional selected k-space data portion; reconstruct (208) a first Dixon water image (152) from the first k-space data group, reconstruct (210) a second Dixon water image (154) from the second k-space data group, and reconstruct (212) an additional magnetic resonance image (156) from each of the at least one additional k-space data group.

The invention relates to a magnetic resonance imaging method and device, computer equipment and a magnetic resonance imaging system, and the method comprises the steps: carrying out the air sweeping of a to-be-imaged object until a steady state of a gradient echo sequence is reached, and carrying out the continuous air sweeping to maintain the steady state of the gradient echo sequence; under the condition that the gradient echo sequence is in a steady state, if a physiological trigger signal is received, applying the gradient echo sequence to the to-be-imaged object, and collecting a magnetic resonance signal of the to-be-imaged object; and reconstructing a magnetic resonance image of the to-be-imaged object according to the magnetic resonance signal. By using the magnetic resonance imaging method, the efficiency of obtaining the magnetic resonance image can be improved.

A system and a method for measuring eddy currents with long time constants includes initiating, via a processor, a calibration scan of a phantom utilizing a magnetic resonance imaging (MRI) scanner. The system and the method also include utilizing, via the processor, a train of gradient echo sequences to simultaneously generate and measure the eddy currents during the calibration scan. Both eddy current generation and measurement are completed within each gradient echo sequence of the train of gradient echo sequences. The system and the method further include acquiring, via the processor, k-space data from the train of gradient echo sequences. The system and the method still further include converting, via the processor, the k-space data to eddy current gradient fields. The system and the method even further include estimating, via the processor, the eddy currents as a function of time based on the eddy current gradient fields.

The present disclosure provides a single-sided magnetic resonance imaging system comprising a plurality of components. The present disclosure also provides a method for generating a multi-dimensional image by using an imaging system. The present disclosure also provides a process of applying multiple xSPEN readout gradients on the single-sided magnetic resonance imaging system disclosed herein. There are several techniques for collecting dynamic magnetic resonance (MR) images. The fast pulse sequence may be used to fast sample the entire k-space, thereby generating images acquired within a small time window. For example, a spiral trajectory gradient echo sequence may be used to sample the entire k-space within tens of milliseconds. Another method is to use small flip angle excitation to quickly collect lines in k-space. These methods may also be combined with undersampling to collect images more quickly.

The invention discloses a multi-parameter quantitative imaging method and device, nuclear magnetic resonance equipment and a storage medium, the multi-parameter quantitative imaging method is applied to the nuclear magnetic resonance equipment, and the nuclear magnetic resonance equipment comprises a T2 preparation sequence module and a variable flip angle multi-echo gradient echo sequence module connected with the T2 preparation sequence module. Comprising the steps that equivalent echo time is controlled through a T2 preparation sequence module, a flip angle is controlled through a variable flip angle multi-echo gradient echo sequence module, a target object is scanned, and a multi-parameter echo signal is obtained; and performing imaging processing on the multi-parameter echo signal based on the image demand configuration information to obtain a required multi-parameter quantitative image. According to the invention, T2 preparation and a variable flip angle technology are combined, and a multi-parameter echo signal can be obtained through one-time scanning, so that a multi-parameter quantitative image is obtained, and the parameter imaging efficiency is improved.

This application discloses a system and method for processing precise synthetic CT images of the spine based on deep learning algorithms for axial spondyloarthritis. The system includes: a data acquisition unit for acquiring three-dimensional T1-weighted multi-gradient echo sequences, T2-weighted sequences, and water-lipid separation sequences obtained from magnetic resonance imaging of the target user's spine; a spatial registration unit for inputting multi-sequence data into a deformable registration network to perform spatial registration of multimodal features; a feature processing unit for fusing the registered multimodal features and performing dual-domain splitting based on an anatomical attention gating mechanism to obtain skeletal features and soft tissue features; and an image fusion unit for synthesizing synthetic CT images with HU values ​​corresponding to the target user's spine based on skeletal features and soft tissue features, achieving radiation-free, high-precision CT image acquisition, which can meet the diagnostic and grading requirements of axial spondyloarthritis while reducing the impact of radiation on the target user.

An ablation calculation method and an ablation calculation system, the ablation calculation method comprising: scanning a target to be measured using a gradient echo sequence containing i different echo times, obtaining a phase map corresponding to the echo time, i being a positive integer greater than or equal to 2 (S101); selecting at least two groups of phase maps corresponding to different echo times to obtain corresponding temperature difference maps (S102); obtaining a temperature map according to the temperature difference maps (S103); calculating an ablation condition according to the temperature map (S104); and the ablation calculation system comprising an ablation calculation module capable of executing the ablation calculation method.

A method of acquiring magnetic resonance (MR) data from a subject using a magnetic resonance imaging (MRI) system includes generating, for each of at least one level in the subject, a first pre-saturated RF pulse having a first flip angle, generating, after each first pre-saturated RF pulse, a series of first gradient echo sequences, and calculating a B0 value for each of the at least one level. A second pre-saturated RF pulse having a second flip angle is generated for each of the at least one planes in the subject, then a series of second gradient echo sequences is generated, and B1 is calculated for each of the at least one planes based on the first gradient echo sequences and the second gradient echo sequences.

The application discloses a kind of optimization methods of residual magnetism measurement process in magnetic resonance imaging system, adopt positive and negative combination gradient as test gradient, the difference of the action of spin echo and gradient echo is combined with magnetic field inhomogeneity, the change of magnetic field uniformity caused by test gradient is measured, then the change of echo peak caused by the change is used to measure the strength of residual magnetism.The method avoids the reference test under the condition that test gradient is zero, overcomes the adverse effects of magnetic hysteresis on reference signal, ensures that the magnetic field distribution state when collecting echo signal in measurement process is determined and stable, eliminates the influence of test sequence on test result, so as to improve the accuracy and stability of residual magnetism measurement result.The method of the application is simple and easy to operate, can measure the spatial anisotropy of residual magnetism, can be used to evaluate the influence of residual magnetism on imaging space positioning, and is especially suitable for judging whether permanent magnetic resonance imaging system meets the requirements of space positioning for monitoring and navigation in interventional therapy.

The invention provides a magnetic resonance parameter determination method and device, electronic equipment and a computer program product, and the method comprises the steps: scanning a scanning object through employing a plurality of gradient echo sequences of different repetition times, and obtaining a magnetic resonance image corresponding to the gradient echo sequence of each repetition time; the radio frequency flip angles set by the plurality of gradient echo sequences are the same; performing nonlinear fitting according to a plurality of different repetition times, a radio frequency flip angle set by the gradient echo sequence, the signal intensity of each magnetic resonance image and a preset signal model to determine a longitudinal relaxation time constant, the independent variables of the signal model including the repetition time and the longitudinal relaxation time constant, the dependent variable of the signal model is the signal intensity of the magnetic resonance image. Therefore, the gradient echo sequences with the same flip angle and different repetition times are adopted for scanning, and nonlinear fitting is performed based on the steady-state signal model, so that the longitudinal relaxation time constant can be quickly and accurately determined without long waiting time.

The invention relates to an improved mute multi-gradient echo magnetic resonance imaging system and method. Methods and systems for generating muted multi-gradient echo magnetic resonance images include employing iterative applications of small updates to the magnetic field gradient followed by short non-selective radio frequency pulse excitation, and for free induction decay data acquisition. Updating of the magnetic field gradient allows for a muted self-refocusing pulse sequence. Each magnetic field gradient is based in part on a k-space spoke. A closed k-space trajectory is generated when multiple spokes are cascaded, which results in a self-refocusing pulse sequence. The k-space spokes in the k-space spoke sequence forming the closed k-space trajectory oscillate inside and outside the plane of the frequency space. Subsequent application of the magnetic field gradient allows multiple echo data acquisition.

Disclosed herein is a medical system (100, 500). The execution of the machine executable instructions (120) causes a computational system (104) to: receive (200) multi-echo gradient echo k-space data (122) comprising multiple in-phase groups (124) of k-space data acquired at echo times that are multiples of an interval when water and fat are in phase; reconstruct (204) a preliminary magnetic resonance image (128) for each of the group of k-space data; construct (206) an averaged magnetic resonance image (130) from the preliminary magnetic resonance images; construct (208) a temporary magnetic resonance image (132) from the preliminary magnetic resonance image with the longest echo time; construct (210) an intermediate magnetic resonance image (134) by subtracting the average magnetic resonance image from the temporary magnetic resonance image; construct (216) a subject mask from a reference scan magnetic resonance image (136); construct (218) a clinical magnetic resonance image (144) by setting pixels of the intermediate magnetic resonance image that are outside of the subject mask to a predetermined background value.

The present application discloses a magnetic resonance temperature imaging method, which comprises the following steps: obtaining a phase map using a gradient echo sequence containing at least two different echo times, obtaining a phase difference map corresponding to at least two different echo times according to the phase map, and in the process of obtaining the phase difference map, using at least one phase difference map corresponding to an echo time as a reference phase difference map to calibrate at least one phase difference map corresponding to a different echo time; obtaining a temperature difference map corresponding to at least two different echo times according to the phase difference map, and obtaining a temperature map corresponding to at least two different echo times by using the temperature difference map; and obtaining a weighted temperature map using the temperature map corresponding to at least two different echo times.