WO2020037814A1 - Procédé et appareil d'imagerie à diffusion par résonance magnétique à voxels égaux fondés sur une excitation simultanée multi-plaque - Google Patents

Procédé et appareil d'imagerie à diffusion par résonance magnétique à voxels égaux fondés sur une excitation simultanée multi-plaque Download PDF

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WO2020037814A1
WO2020037814A1 PCT/CN2018/112353 CN2018112353W WO2020037814A1 WO 2020037814 A1 WO2020037814 A1 WO 2020037814A1 CN 2018112353 W CN2018112353 W CN 2018112353W WO 2020037814 A1 WO2020037814 A1 WO 2020037814A1
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excitation
image
plate
magnetic resonance
multiple plates
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戴二鹏
郭华
吴宥萱
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Tsinghua University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver

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  • the present invention relates to the technical field of magnetic resonance diffusion imaging, and in particular, to a method and device for iso-voxel magnetic resonance diffusion imaging based on simultaneous excitation of multiple plates.
  • Magnetic resonance diffusion imaging technology is currently the only imaging method for measuring the diffusion motion of water molecules in vivo. It detects the microstructure of tissues by applying a diffusion gradient to sense the microscopic motion of water molecules. It can obtain both structural information and functional information. Therefore, This technology has developed rapidly in the past two decades and has gradually become an important routine clinical examination and scientific research tool.
  • the conventional magnetic resonance diffusion imaging technology in neuroscience and clinical diagnosis is single-shot EPI (echoplanar imaging).
  • the single-shot EPI completes the acquisition of the entire k-space after a single-layer excitation of RF (radiofrequency, radio frequency) pulses, which has the advantages of fast imaging speed, insensitivity to motion, and relatively simple reconstruction algorithm.
  • RF radiofrequency, radio frequency
  • high-resolution voxel diffusion imaging technology is of great significance in neuroscience research, especially in detecting the microstructure and regional connections of the brain.
  • high-resolution voxel-diffusion imaging can help more accurately distinguish between different nerve fiber structures; better detect gray matter boundaries; and more accurately detect complex nerve fiber structures such as bends and Crossed nerve fibers.
  • the main challenge of high-resolution voxel diffusion imaging is how to ensure that the diffusion image has a sufficient signal-to-noise ratio without reducing the imaging efficiency.
  • the ultra-high field magnetic resonance scanner can increase the strength of the signal itself, and is used to compensate for the loss of signal-to-noise ratio caused by high resolution.
  • the ultra-high field magnetic resonance scanner also has its own limiting factors: the B 0 / B 1 magnetic field is more uneven, the T 2 / T 2 * decay time constant becomes shorter, the energy deposition effect increases, and so on.
  • the second scheme is to use a high SNR efficiency acquisition strategy.
  • the first category is the SMS (simultaneous multi-slice) technology.
  • the TR time can be shortened to 1 / R SMS of the traditional two-dimensional imaging method.
  • the second type of method is the three-dimensional multi-plate acquisition technology: firstly, a "thick layer" is excited, and then three-dimensional Fourier coding is used to reconstruct a high-resolution diffusion image such as voxels.
  • three-dimensional multi-plate diffusion imaging since the plate excited each time is relatively thick, there are fewer N slices (or N slabs ) in a single TR (repetition time) and the TR time is relatively short.
  • the present invention aims to solve at least one of the technical problems in the related technology.
  • an object of the present invention is to propose an iso-voxel magnetic resonance diffusion imaging method based on simultaneous excitation of multiple plates, which can obtain high-resolution images while still maintaining a high signal-to-noise ratio and reducing three-dimensional
  • the interference of the navigation echo error improves the quality and stability of the reconstructed image, and improves the signal-to-noise ratio efficiency and scanning efficiency on the basis of ensuring the image quality.
  • Another object of the present invention is to provide an iso-voxel magnetic resonance diffusion imaging device based on simultaneous excitation of multiple plates.
  • an embodiment of the present invention provides an iso-voxel magnetic resonance diffusion imaging method based on simultaneous excitation of multiple plates, including the following steps: Step S1: Exciting pulses simultaneously through multiple plates to perform multi-target detection. For each excitation, and during each excitation, signal acquisition is performed on the measured target through a multi-channel coil to obtain k-space data for each excitation reduction; step S2: through the combined k-space and image domain The multiple-excitation diffusion imaging reconstruction algorithm recovers the k-space position data that was not collected for each excitation; step S3: correct the edge artifacts by using the improved NPEN algorithm to obtain imaging images.
  • the isovoxel magnetic resonance diffusion imaging method based on simultaneous excitation of multiple plates can acquire high-resolution images while maintaining a high signal-to-noise ratio while using a three-dimensional multi-plate acquisition technology; the proposed combination K-space and image domain phase correction algorithms reduce the interference of 3D navigation echo errors and improve the quality and stability of reconstructed images; combined with the use of multi-plate simultaneous excitation technology, on the basis of ensuring image quality, improve the signal-to-noise ratio efficiency and scanning effectiveness.
  • the iso-voxel magnetic resonance diffusion imaging method based on the simultaneous excitation of multiple plates may also have the following additional technical features:
  • the step S1 further includes: applying different phase compensation to the sub-pulses of different plates in the multi-plate to eliminate the phase error generated by the plate interval; and / or During each excitation process, navigation echoes are collected to obtain phase information for each excitation, wherein the simultaneous excitation pulses of the multiple plates are represented as:
  • RF is a single-layer excited RF pulse
  • R SMS is the number of simultaneous excitation layers
  • i is the i-th layer that is excited simultaneously
  • ⁇ i is the frequency modulation
  • ⁇ i ⁇ ⁇ (i-1) ⁇ G ⁇ d
  • ⁇ is the spin Magnetic ratio
  • G is the gradient of layer selection
  • d is the center distance between two adjacent layers. It is the phase error generated by the plate interval in the gradient encoding process.
  • the step S2 further comprises: restoring the initial diffusion image for each excitation through a 2D CK-GRAPPA algorithm; and reconstructing by POCSMUSE to introduce coil sensitivity and phase smoothing constraints to reduce residual artifact And noise, the reconstruction diffusion image is estimated for each excitation, and is continuously updated in each iteration to obtain the final diffusion image for each excitation.
  • the improved NPEN algorithm is to obtain a non-linear optimization problem according to the contour coding of the plate level, and to solve the non-linear optimization problem by inverse of a non-linear equation, and in the process of solving , Iteratively optimizes the slice-level contours to correct the edge artifacts.
  • the target equation of plate edge artifact correction is:
  • n represents the n-th sector
  • P is the operator that selects the corresponding collected k-space position
  • F is the Fourier transform
  • C is the coil sensitivity code. It is the slice contour of simultaneous excitation pulses of multiple plates, ⁇ is the image to be reconstructed.
  • an embodiment of another aspect of the present invention proposes an iso-voxel magnetic resonance diffusion imaging device based on simultaneous excitation of multiple plates, including: an acquisition module for simultaneously exciting pulses through multiple plates to perform a measurement on a target to be measured. Multiple excitations, and during each excitation, signal acquisition is performed on the measured target through a multi-channel coil to obtain k-space data that is reduced for each excitation; a reconstruction module is used to pass the joint k-space The multiple-excitation diffusion imaging reconstruction algorithm in the image field and the image domain recovers the k-space position data that is not collected for each excitation; a correction module is used to correct edge artifacts through an improved NPEN algorithm to obtain an imaging image.
  • the iso-voxel magnetic resonance diffusion imaging device based on simultaneous excitation of multiple plates can acquire high-resolution images while still maintaining a high signal-to-noise ratio by using three-dimensional multi-plate acquisition technology; the proposed combination K-space and image domain phase correction algorithms reduce the interference of 3D navigation echo errors and improve the quality and stability of reconstructed images; combined with the use of multi-plate simultaneous excitation technology, on the basis of ensuring image quality, improve the signal-to-noise ratio efficiency and scanning effectiveness.
  • the iso-voxel magnetic resonance diffusion imaging device based on simultaneous excitation of multiple plates may also have the following additional technical features:
  • the acquisition module is further configured to apply different phase compensation to the sub-pulses of different plates in the multi-plate to eliminate phase errors generated by the plate interval; and / or During each excitation process, navigation echoes are collected to obtain phase information for each excitation.
  • the reconstruction module is further configured to recover an initial diffusion image for each excitation through a 2D CK-GRAPPA algorithm; and reconstructing by POCSMUSE to introduce coil sensitivity and phase smoothing constraints to reduce residual artifacts And noise, the reconstruction diffusion image is estimated for each excitation, and is continuously updated in each iteration to obtain the final diffusion image for each excitation.
  • the improved NPEN algorithm is to obtain a non-linear optimization problem according to the contour coding of the plate level, and to solve the non-linear optimization problem by inverse of a non-linear equation, and in the process of solving , Iteratively optimizes the slice-level contours to correct the edge artifacts.
  • the target equation of plate edge artifact correction is:
  • n represents the n-th sector
  • P is the operator that selects the corresponding collected k-space position
  • F is the Fourier transform
  • C is the coil sensitivity code. It is the slice contour of simultaneous excitation pulses of multiple plates, ⁇ is the image to be reconstructed.
  • FIG. 1 is a flowchart of an isotope voxel magnetic resonance diffusion imaging method based on simultaneous excitation of multiple plates according to an embodiment of the present invention
  • FIG. 2 is a sequence diagram of simultaneous excitation magnetic resonance diffusion imaging of a multi-plate with navigation echo based on spin echo based on an embodiment of the present invention
  • FIG. 3 is a schematic diagram of the shapes of excitation pulses and first refocusing pulses in 4 different kz planes according to an embodiment of the present invention
  • FIG. 5 is a schematic structural diagram of an isotope magnetic resonance diffusion imaging device based on simultaneous excitation of multiple plates according to an embodiment of the present invention.
  • FIG. 1 is a flowchart of an iso-voxel magnetic resonance diffusion imaging method based on simultaneous excitation of multiple plates according to an embodiment of the present invention.
  • the iso-voxel magnetic resonance diffusion imaging method based on simultaneous excitation of multiple plates includes the following steps:
  • Step S1 Simultaneous excitation of pulses through multiple plates to perform multiple excitations on the measured target, and during each excitation, signal acquisition is performed on the measured targets through multi-channel coils to obtain the k-space for each excitation reduction. data.
  • step S1 further includes: applying different phase compensation to the sub-pulses of different plates in the multiple plates to eliminate the phase error generated by the plate interval; and / or during each excitation, Acquire navigation echoes to obtain phase information for each shot.
  • RF represents a single-layer excited RF pulse
  • ⁇ i frequency modulation
  • ⁇ i ⁇ ⁇ (i-1) ⁇ G ⁇ d
  • ⁇ is a gyromagnetic ratio (2 ⁇ ⁇ 42.575MHz for H 1 )
  • i indicates simultaneous excitation.
  • G is the selection gradient
  • d is the center interval between two adjacent layers
  • R SMS is the number of simultaneous excitation layers.
  • phase generated by the gradient encoding is related to the position.
  • plate spacing will bring additional phase error, and its size is:
  • d slab represents the interval between two adjacent plates
  • k z is the index of the collected k space in the layer direction
  • R SMS is the number of plates excited at the same time
  • N is the number of layers to be reconstructed for each plate
  • ⁇ z is the desired High resolution of reconstructed layer orientation.
  • the spin-echo based multi-plate simultaneous magnetic resonance diffusion imaging sequence with navigation echo is shown in Figure 2.
  • the excitation pulse and the first refocusing pulse (for generating imaging echo) can be designed according to Equation 3.
  • Equation 2 for different kz, The sizes are different, that is, the RF SMSlab shapes corresponding to different kz are not exactly the same.
  • Figure 3 shows the shape of the excitation pulse and the first refocusing pulse in 4 different kz planes.
  • multi-plate excitation pulse is the basic composition of the multi-plate excitation pulse.
  • more advanced SLR designs can be used for basic RF pulses.
  • multi-plate excitation pulses can use more advanced designs, such as VERSE, PINS, etc. ⁇ i and Optimized so that the final RF SMSlab only has amplitude information, which can achieve better performance on some systems.
  • a navigation echo needs to be collected for each excitation pair to record the phase information of each excitation. Because navigation echoes are usually collected using a single-shot EPI, phase interference caused by plate spacing cannot be resolved by the RF pulse coding method described above, so three-dimensional navigation echoes cannot be directly collected. At the same time, it is considered that the phase change along the layer direction in each plate is not large, so a two-dimensional navigation echo is collected each time it is excited. It is worth noting that the shape of the second refocusing pulse does not match the shape of the first refocusing pulse. Assuming the first refocusing pulse is shown in Equation 3, the second refocusing pulse is:
  • the signal acquisition may use an imaging sequence with multiple excitations with navigation data, such as, but not limited to, multiple excitation EPI diffusion imaging with navigation data, propeller diffusion imaging, or multiple excitation spiral diffusion imaging .
  • the embodiments of the present invention are not limited to the types of imaging methods with multiple excitations.
  • the navigation data may be self-navigation data (such as VDS (variable density spiral)), or it may be navigation data acquired in addition.
  • a set of low-resolution images is acquired in advance ("calibration scan 1").
  • the pulse sequence can be different from the above-mentioned real image acquisition, and the traditional two-dimensional acquisition method is usually used.
  • the coil sensitivity is transformed to the corresponding position of the real image through operations such as interpolation.
  • step S3 In order to estimate the RF pulse slice profile required in step S3, an additional set of non-diffusion-coded calibration data is acquired in advance ("calibration scan 2"). Oversampling 2 times in the kz direction, using the same pulse shape as the real image acquisition, and keeping the TR consistent.
  • Step S2 The k-space position data that is not collected for each excitation is restored by a multiple excitation diffusion imaging reconstruction algorithm combining k-space and image domain.
  • the embodiment of the present invention proposes a multiple-excitation diffusion imaging reconstruction technique that combines k-space and image domains, recovers data of k-space positions that are not collected for each excitation, and corrects phase changes between different excitations.
  • the complete k-space data of each excitation is recovered to perform inverse Fourier transform, and the images of each excitation are complexly combined.
  • the reconstruction technology of parallel imaging is used to restore the navigation echo data of each excitation to a complete k-space.
  • the recovery process can use k-space algorithms (such as GRAPPA).
  • k-space algorithms such as GRAPPA
  • the k-space-based data interpolation process can be expressed by the following formula:
  • d j (m, n, p) is the k-space data corresponding to the j-th channel of the data point to be restored, and (m, n, p) is the kx-ky-kz coordinate of the point to be interpolated
  • d j ' ( m ', n', p ') is the k-space data collected by the interpolation kernel on the j'th channel
  • (m', n ', p') is the kx- of the points collected by the interpolation kernel (represented by K) ky-kz coordinates
  • w 1 (j ′, m ′, n ′, p ′) is the weight coefficient corresponding to the j′-th channel and data point (m ′, n ′, p ′), which can be estimated from the data of calibration scan 1.
  • step S2 further includes: restoring the initial diffusion image for each excitation by a 2D CK-GRAPPA algorithm; and reconstructing by POCSMUSE to introduce coil sensitivity and phase smoothing constraints to reduce residual artifacts and noise ,
  • the reconstructed diffusion image for each excitation is estimated and continuously updated in each iteration to obtain the final diffusion image for each excitation.
  • step 1 The specific interpolation process using the 2D CK-GRAPPA algorithm can be expressed by the following formula:
  • d i, j (m, n, p) is the k-space data corresponding to the i-th excitation and j-th channel of the data point to be recovered, and (m, n, p) is the kx-ky- kz coordinates; d i ', j' (m ', n', p ') is the k-space data collected by the interpolation kernel at the i'th excitation and j'th channel, (m', n ', p' ) Is the kx-ky-kz coordinates of the points collected by the interpolation kernel (represented by K); i, i' ⁇ (1, N shot ), N shot is the total number of shots; j, j' ⁇ (1, N c ), N c is the total number of channels.
  • w 2 is a weight matrix, which can be calculated from the restored navigation echo (formula 5), and the specific process is similar to that of formulas 6 to 8.
  • Step 2 On the basis of 2D CK-GRAPPA, plus POCSMUSE reconstruction, by introducing coil sensitivity and phase smoothing constraints, the residual artifacts and noise are further reduced.
  • the initial phase map is estimated from the diffusion image of each excitation reconstructed by 2DCK-GRAPPA, and is continuously updated in each iteration.
  • the termination condition of POCSMUSE is that the error between two successive iterations is less than a preset threshold, or the number of iterations is equal to a preset value. Among them, the overall reconstruction process is shown in Figure 4.
  • Step S3 The edge artifact is corrected by the improved NPEN algorithm to obtain an imaging image.
  • the improved NPEN algorithm is to obtain a non-linear optimization problem according to the contour coding of the plate level, and solve the non-linear optimization problem by inverse of a non-linear equation, and in the process of solving, iteratively optimize the plate Layer contours to correct edge artifacts.
  • RF pulse level profile should be rectangular, and its layer selection width is equal to the layer thickness, but it requires an infinitely long pulse time, so it is impossible to achieve in practice.
  • RF pulses In practice, due to various practical factors such as the truncation effect in the time domain, RF pulses always produce non-ideal layer contours, such as Gibbs ringing artifacts, transition bands, etc. Wait. In 3D multi-plate imaging, if the reconstructed "thin layer" is located in the transition zone area, the actual signal amplitude is lower than the theoretical value.
  • the size of the field-of-view (FOV) of the spatial coding of the layer selection direction is generally smaller than the excited FOV, resulting in aliasing artifacts. There may be overlap between adjacent plates, causing crosstalk between plates.
  • PEN believes that plate edge artifacts are linear coding problems, which can be solved by linear equation inversion. PEN can effectively solve the problem of aliasing between plates, but there may be residual plate crosstalk artifacts, especially at short TR.
  • NPEN is based on PEN. Plate-level contour coding is considered as a non-linear optimization problem, which can be solved using the method of inverse of nonlinear equations, and iteratively optimizes the plate-level contour during the solution process.
  • the objective equation of NPEN can be written as follows:
  • ⁇ is the image to be reconstructed
  • N is the total number of plates
  • E is a non-linear coding matrix, and is composed of three parts: C is the coil sensitivity code, which can be estimated from calibration scan 1, F is the Fourier transform, P is an operator that selects the corresponding acquired k-space position.
  • the main challenge is that the aliasing form of plate edge artifacts will change: from intra-slab aliasing to inter-slab aliasing, so the original plate
  • the objective equation of edge artifact correction needs corresponding improvement, as shown in the following formula.
  • the algorithm for solving the objective equation can be as before.
  • the target equation of plate edge artifact correction is:
  • n represents the n-th sector
  • P is the operator that selects the corresponding collected k-space position
  • F is the Fourier transform
  • C is the coil sensitivity code. It is the slice contour of simultaneous excitation pulses of multiple plates, ⁇ is the image to be reconstructed.
  • the embodiment of the present invention uses magnetic resonance diffusion imaging as an example to introduce the proposed image acquisition and reconstruction strategy, but is not limited to diffusion imaging.
  • the related image acquisition and reconstruction methods can be applied to other imaging modes, such as functions Magnetic resonance imaging (fMRI).
  • fMRI Magnetic resonance imaging
  • the acquisition module is as described above.
  • a three-dimensional multi-plate diffusion imaging sequence is designed to acquire signals.
  • the reconstruction module is simpler and there is no phase inconsistency between different excitations.
  • you can directly use traditional parallel imaging reconstruction algorithms such as 2D GRAPPA).
  • the multi-layer simultaneous excitation technology and the three-dimensional multi-plate imaging technology are further combined to achieve high-resolution voxel imaging while improving imaging efficiency and signal-to-noise ratio efficiency.
  • the iso-voxel magnetic resonance diffusion imaging method based on simultaneous excitation of multiple plates by using a three-dimensional multi-plate acquisition technology, a high-resolution image can be acquired while maintaining a high signal-to-noise ratio; Phase correction algorithm that combines k-space and image domain, reduces the interference of 3D navigation echo error, improves the quality and stability of reconstructed image; combined with the use of multi-plate simultaneous excitation technology, improves the signal-to-noise efficiency on the basis of ensuring image quality And scanning efficiency.
  • FIG. 5 is a schematic structural diagram of an iso-voxel magnetic resonance diffusion imaging device based on simultaneous excitation of multiple plates according to an embodiment of the present invention.
  • the iso-voxel magnetic resonance diffusion imaging apparatus 10 based on simultaneous excitation of multiple plates includes: an acquisition module 100, a reconstruction module 200, and a correction module 300.
  • the acquisition module 100 is used for simultaneously stimulating pulses through multiple plates to perform multiple excitations on the measured target, and during each excitation, signal acquisition is performed on the measured target through a multi-channel coil to obtain each excitation drop.
  • the reconstruction module 200 is configured to recover k-space position data that is not collected for each excitation through multiple excitation diffusion imaging reconstruction algorithms combining k-space and image domain.
  • the correction module 300 is configured to correct edge artifacts by using an improved NPEN algorithm to obtain an imaging image.
  • the device 10 can maintain a high signal-to-noise ratio while acquiring a high-resolution image, and reduce the interference of three-dimensional navigation echo errors, improve the quality and stability of the reconstructed image, and ensure the quality of the image. In order to improve the signal-to-noise ratio efficiency and scanning efficiency.
  • the acquisition module 100 is further configured to apply different phase compensation to the sub-pulses of different plates in the multiple plates to eliminate the phase error generated by the plate interval; and / or at each excitation In the process of collecting navigation echoes to obtain phase information of each excitation, wherein the simultaneous excitation pulses of the multiple plates are expressed as:
  • RF is a single-layer excited RF pulse
  • R SMS is the number of simultaneous excitation layers
  • i is the i-th layer that is excited simultaneously
  • ⁇ i is the frequency modulation
  • ⁇ i ⁇ ⁇ (i-1) ⁇ G ⁇ d
  • ⁇ is the spin Magnetic ratio
  • G is the gradient of layer selection
  • d is the center distance between two adjacent layers. It is the phase error generated by the plate interval in the gradient encoding process.
  • the reconstruction module 200 is further configured to recover the initial diffusion image for each excitation by the 2D CK-GRAPPA algorithm; and reconstruct the POCSMUSE to introduce coil sensitivity and phase smoothing constraints to reduce residual artifacts and Noise, reconstructed diffusion image estimates for each excitation, and continuously update in each iteration to obtain the final diffusion image for each excitation.
  • the improved NPEN algorithm is to obtain a non-linear optimization problem according to the contour coding of the plate level, and to solve the non-linear optimization problem by inverse of the non-linear equation, and in the process of solving, iterative optimization Plate-level contours to correct edge artifacts.
  • the target equation of plate edge artifact correction is:
  • n represents the n-th sector
  • P is the operator that selects the corresponding collected k-space position
  • F is the Fourier transform
  • C is the coil sensitivity code. It is the slice contour of simultaneous excitation pulses of multiple plates, ⁇ is the image to be reconstructed.
  • an iso-voxel magnetic resonance diffusion imaging device based on simultaneous excitation of multiple plates can acquire high-resolution images while maintaining a high signal-to-noise ratio by using three-dimensional multi-plate acquisition technology.
  • Phase correction algorithm that combines k-space and image domain, reduces the interference of 3D navigation echo error, improves the quality and stability of reconstructed image; combined with the use of multi-plate simultaneous excitation technology, improves the signal-to-noise efficiency on the basis of ensuring image quality And scanning efficiency.
  • first and second are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as “first” and “second” may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "a plurality” is at least two, for example, two, three, etc., unless it is specifically and specifically defined otherwise.

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Abstract

L'invention concerne un procédé et un appareil d'imagerie à diffusion par résonance magnétique à voxels égaux fondés sur une excitation simultanée à plaques multiples. Le procédé comprend : étape S1 : la réalisation d'une excitation sur une cible à tester à de nombreuses reprises au moyen d'une impulsion d'excitation simultanée à plusieurs plaques, et dans le processus de chaque excitation, la réalisation d'une acquisition de signal sur la cible à tester au moyen d'une bobine multicanal, ce qui permet d'obtenir des données d'espace k acquises au moyen d'un sous-échantillonnage dans chaque excitation ; étape S2 : par l'intermédiaire d'un algorithme de reconstruction d'imagerie par diffusion à excitation multiple qui réunit un espace k et un domaine d'image, la récupération de données de position d'espace k qui ne sont pas acquises dans chaque excitation ; et S3, la correction d'un artéfact de bord au moyen d'un algorithme NPEN amélioré, ce qui permet d'obtenir une image imagée. Selon le procédé, des images à haute résolution sont acquises tout en permettant de maintenir simultanément un rapport signal sur bruit relativement élevé ; une interférence d'erreurs d'écho de navigation tridimensionnelles est réduite, la qualité et la stabilité des images reconstruites sont améliorées et l'efficacité de rapport signal sur bruit et l'efficacité de balayage sont améliorées conformément à la garantie de la qualité d'images.
PCT/CN2018/112353 2018-08-23 2018-10-29 Procédé et appareil d'imagerie à diffusion par résonance magnétique à voxels égaux fondés sur une excitation simultanée multi-plaque Ceased WO2020037814A1 (fr)

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