CN117011409A - Multi-position physical intelligent high-definition diffusion magnetic resonance data generation method - Google Patents

Multi-position physical intelligent high-definition diffusion magnetic resonance data generation method Download PDF

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CN117011409A
CN117011409A CN202311004982.7A CN202311004982A CN117011409A CN 117011409 A CN117011409 A CN 117011409A CN 202311004982 A CN202311004982 A CN 202311004982A CN 117011409 A CN117011409 A CN 117011409A
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屈小波
管飞强
钱晨
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Abstract

The multi-part physical intelligent high-definition diffusion magnetic resonance data generation method comprises 1) generating a simulated high-definition diffusion magnetic resonance amplitude diagram by using a diffusion physical model; 2) Generating a high-order simulation motion phase of each excitation diffusion image based on the physical motion model; 3) Combining the simulated diffusion magnetic resonance amplitude diagram, the high-order simulated motion phase diagram and the acquired multichannel coil sensitivity map, transforming to k space by utilizing Fourier transformation to obtain fully sampled network training tag data, and 4) adding Gaussian noise to obtain noisy k space data; 5) Undersampling noisy k-space data according to a sampling track of an acquisition sequence of high-definition diffusion data of a target to obtain simulated multichannel multi-excitation diffusion magnetic resonance data with motion artifact interference; 6) Repeating 1) to 5) to generate network training input data and full-sampling training label data; 7) And (3) utilizing the generated diffusion magnetic resonance data set training neural network to realize reconstruction or denoising of the actual measurement high-definition diffusion magnetic resonance data.

Description

Multi-position physical intelligent high-definition diffusion magnetic resonance data generation method
Technical Field
The invention relates to a generation method based on multichannel multi-excitation diffusion image data, in particular to a generation method for generating paired multi-part physical intelligent high-definition diffusion magnetic resonance data by using a diffusion physical model and a high-order physical motion phase model, wherein the generated data can be used for training of a reconstructed neural network.
Background
Diffusion weighted imaging (Diffusion weighted imaging) is a way to assess human molecular function and microstructure and to detect the diffusion movement of water molecules in tissues without intrusion (v.baliyan et al., "Diffusion weighted imaging: technique and applications," World Journal of Radiology,8,785,2016). Multi-shot planar echo imaging techniques have the ability to improve resolution and reduce low-distortion in diffusion weighting applications (H.An, X.Ma, Z.Pan, H.Guo, E.Y.P.Lee, "Qualitative and quantitative comparison of image quality between single-shot echo-planar and interleaved multi-shot echo-planar dispersion-weighted imaging in female pelvis," European radiology,30,1876-1884,2020). However, there is a severe phase error between the different excitations, resulting in severe motion artifacts (A.W.Anderson, J.C.Gore, "Analysis and correction of motion artifacts in diffusion weighted imaging," Magnetic Resonance in Medicine,32,379-387,1994).
Recently, the deep learning approach has shown great potential in multi-shot diffusion weighted imaging (Aggarwal.H.K., M.Mani, M.Jacob, "MoDL-MUSSELS: model-based deep learning for multi-shot sensitivity-encoded diffusion MRI", IEEE Transactions on Medical Imaging,39,1268-1277,2019). However, the multi-shot diffusion weighted image lacks high quality training labels, the training labels generated using conventional iterative reconstruction methods (C.Qian et al., "A paired phase and magnitude reconstruction for advanced diffusion-weighted imaging," IEEE Transactions on Biomedical Engineering, DOI:10.1109/TBME.2023.3288031, 2023) are a popular solution (F.Wang et al., "Multiple b-value model-based residual network (MORN) for accelerated high-resolution-weighted imaging," IEEE Journal ofBiomedical and Health Informatics,26,4575-4586,2022), but it greatly limits the potential of these intelligent reconstruction methods: (1) The traditional iterative reconstruction method generally needs extremely long time to generate a large number of training labels, and the parameter adjustment is complicated, so that the robust reconstruction is difficult to obtain on a large actual measurement data set; (2) The performance of the deep learning method will be limited by the tag generation method; (3) Due to insufficient data sets, the deep learning method is poor in generalization under the reconstruction of multiple scenes such as multiple resolutions, multiple b values, multiple manufacturers, multiple undersamples and the like; (4) The measured data collection is time consuming and is more limited because of privacy concerns. Meanwhile, the traditional iterative reconstruction method is only suitable for rigid motion, and the abdomen has more complex elastic motion, so that the invention adopts a high-order physical motion phase simulation model in motion phase simulation.
In summary, the current intelligent reconstruction method of high-definition diffusion imaging is limited by the bottleneck of high-quality paired training data, and the potential of the intelligent reconstruction method cannot be effectively exerted.
Disclosure of Invention
The invention aims to provide a multi-position physical intelligent high-definition diffusion magnetic resonance data generation method capable of rapidly generating multi-b-value, multi-resolution, multi-sampling-rate and multi-sequence high-definition diffusion imaging data.
The invention comprises the following steps:
1) Generating a simulation high-definition diffusion magnetic resonance amplitude diagram by using diffusion physical models such as diffusion indexes, tensors, kurtosis and the like;
2) Generating a high-order simulation motion phase diagram of each excitation diffusion image based on the physical motion model;
3) Combining the generated simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map, and transforming the simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map into k space by utilizing Fourier transformation to obtain fully-sampled network training label data;
4) Adding Gaussian noise into the full-sampling training label data to obtain noisy k-space data;
5) Undersampling noisy k-space data according to a sampling track of an acquisition sequence of high-definition diffusion data of a target to obtain simulated multichannel multi-excitation diffusion magnetic resonance data with motion artifact interference, wherein the simulated multichannel multi-excitation diffusion magnetic resonance data is used as input data of network training;
6) Repeating steps 1) to 5) in a large number to generate a large number of paired network training input data and full-sampling training label data;
7) Training a neural network by using the generated diffusion magnetic resonance data set, wherein the network is used for reconstructing or denoising the high-definition diffusion magnetic resonance data after training.
In step 1), the generated simulated high-definition diffusion magnetic resonance amplitude graph can be generated by diffusion physical models such as diffusion indexes, tensors, kurtosis and the like:
(diffusion single exponential model) m (b) =exp { -bdadc } m 0 (1)
Wherein,for diffusion magnitude image with diffusion b value b, < ->For diffusion images where no diffusion gradient is applied, the ADC is an apparent diffusion coefficient matrix.
(diffusion tensor model) m (b, g) =exp { -bg T Dg}m 0 (2)
Wherein,for diffusion amplitude image with diffusion b value b in diffusion gradient direction g, +.>For a diffusion image to which no diffusion gradient is applied, g represents a single diffusion gradient directionBit vector, T is the transposed symbol, and D is the diffusion tensor matrix.
(diffusion kurtosis model)Wherein (1)>For diffusion amplitude image with diffusion b value b in diffusion gradient direction g, +.>For a diffusion image to which a diffusion gradient is not applied, g represents a unit vector of a diffusion gradient direction, D is a diffusion tensor matrix, and K is a diffusion kurtosis matrix.
The constants of ADC, D, K and the like with tissue diffusion information in the diffusion single-index, tensor, kurtosis and other physical models can be calculated by acquiring actual diffusion images with enough diffusion b values and diffusion direction numbers through linear fitting and other algorithms.
Thus, given the diffusion direction g and b value b, a diffusion magnitude image m of the target diffusion direction and b value can be generated with constants of ADC, D, K, etc. known.
In step 2), the high-order simulated motion phases of each excitation-diffusion image can be generated by a physical motion model:
wherein the diagonal matrixThe phase obtained by simulation of the model is that N and M are the length of the frequency code and the phase code of the image respectively, x and y are coordinates on a selected layer of the two-dimensional image, and i is an imaginary symbol. L is the highest order of the single expressions in the polynomial model, m and L-m are the powers of the single expressions x and y in the current first order polynomial, A lm Is the corresponding item x m y l-m Is a coefficient of (a).By using an L-order polynomial phase model, J motion phases can be obtained by fitting the motion phases of the measured data through phase unwrapping and phase crimping operations>J is the excitation times of the multi-excitation diffusion weighted data to be reconstructed; and then according to the distribution rule of polynomial coefficients in the L-order polynomial phase model, a large number of polynomial coefficients meeting the distribution rule can be obtained to form a simulation phase set. The motion conditions of different parts are different, the brain, the prostate and other parts can be approximately modeled as rigid motion, and a motion model with L=3 is used for simulating motion phases; the abdominal liver and pancreas have more complex elastic motions, and the motion model of l=7 or higher order is used to approximate the simulated motion phase.
In step 3), the generated simulated high definition diffusion magnetic resonance amplitude mapHigh-order simulation motion phase diagram->And an acquired multichannel coil sensitivity map +.>Combining according to the following formula to obtain fully sampled network training label data:
wherein,is +.>Or in a non-Cartesian coordinate system>Fourier transform operator of>Is synthesized H channel J-time excited full-sampling k-space data as network training label data.
In step 4), gaussian noise is added to the fully sampled training tag data to obtain noisy k-space data as follows:
wherein,is Gaussian noise with real and imaginary parts satisfying mean value mu and variance sigma, < >>Is noisy fully sampled k-space data with a signal-to-noise ratio (dB) of X GT And calculating to obtain the noiseless reference diagram.
In step 5), undersampling the noisy k-space data according to a sampling track of an acquisition sequence of the high-definition diffusion data of the target to obtain simulated multichannel multi-excitation diffusion magnetic resonance data with motion artifact interference, wherein the simulated multichannel multi-excitation diffusion magnetic resonance data is used as input data of network training and comprises the following steps:
wherein,is simulated multichannel multi-excitation diffusion magnetic resonance data of motion artifact interference, is taken as input data of network training, and is a sampling template ∈>Can be used forSampling tracks for a plurality of multi-excitation diffusion sequences, in the case of Cartesian coordinates +.>Sampling template->Multi-shot staggered planar echo sequence (multi-shot interleaved echo planer imaging, ms-iEPI), multi-shot read-out-segmented echo planer imaging, ms-rsEPI), etc. can be selected; when in a non-Cartesian coordinate systemSampling template->A multi-shot helical (ms-helical) sampling sequence, a multi-shot propeller (ms-propeller) sampling sequence, and the like may be selected. The number of shots was set to J.
In step 6), repeating steps 1) to 5) K times to generate K-component-pair network training input data X inp And full sample training tag data X GT Thereby constructing a high-quality paired high-definition diffusion imaging training data set based on physical intelligence and containing K samples.
In step 7), the generated diffusion magnetic resonance data set may be used to train a neural network, after which the network may be used to reconstruct or denoise the high-definition diffusion magnetic resonance data.
The invention provides a physical intelligent data generation method based on a physical intelligent driving data generation scheme (Q.Yang, Z.Wang, K.Guo, C.Cai and X.Qu, "Physics-driven syntheticdata learning for biomedical magnetic resonance: the imaging Physics based data synthesis paradigm for artificial intelligence," IEEE SignalProcessing Magazine,40,129-140,2023). Compared with brain rigid body motion modeling (C.Qian et al, "Physics-informed deep diffusion reconstruction: break the bottleneck of training data in artificial intelligence", arXiv:2210.11388,2023), the random high-order motion phase model provided by the invention is suitable for fitting non-rigid body elastic motion, can rapidly generate multi-b-value, multi-resolution, multi-sampling rate and multi-sequence high-definition diffusion imaging data, breaks through the bottleneck that the existing high-definition diffusion magnetic resonance intelligent network depends on actual measurement data, lacks high-quality training labels, and has wide application prospect.
Drawings
FIG. 1 is a flow chart of an embodiment of the present invention.
FIG. 2 is a sequence sampling template for constructing undersampled network input dataRespectively (a) 4-time excitation staggered plane echo sequences and (b) 4-time excitation read-out dimension segmented plane echo sequences.
FIG. 3 is a representation of physical intelligent simulation data versus image domain. (a) brain high-definition diffusion data based on 4-shot staggered plane echoes, (b) abdomen high-definition diffusion data based on 4-shot segmented plane echoes, and (c) brain diffusion data based on a single-shot plane echo sequence.
Detailed Description
The embodiment of the invention comprises a specific process of generating brain and abdomen multi-excitation physical intelligent high-definition diffusion magnetic resonance data, and the method for generating the multi-position physical intelligent high-definition diffusion magnetic resonance data is described in detail by combining with a drawing.
Example 1
The brain high-definition diffusion data generation and reconstruction network training process based on four excitation staggered plane echoes is shown in the flow chart of fig. 1, and is described in detail as follows:
the embodiment of the invention comprises the following steps:
1) Generating a simulation high-definition diffusion magnetic resonance amplitude diagram by using diffusion physical models such as diffusion indexes, tensors, kurtosis and the like;
2) Generating a high-order simulation motion phase diagram of each excitation diffusion image based on the physical motion model;
3) Combining the generated simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map, and transforming the simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map into k space by utilizing Fourier transformation to obtain fully-sampled network training label data;
4) Adding Gaussian noise into the full-sampling training label data to obtain noisy k-space data;
5) Undersampling noisy k-space data according to a sampling track of an acquisition sequence of high-definition diffusion data of a target to obtain simulated multichannel multi-excitation diffusion magnetic resonance data with motion artifact interference, wherein the simulated multichannel multi-excitation diffusion magnetic resonance data is used as input data of network training;
6) Repeating steps 1) to 5) in a large number to generate a large number of paired network training input data and full-sampling training label data;
7) Training a neural network by using the generated diffusion magnetic resonance data set, wherein the network is used for reconstructing or denoising the high-definition diffusion magnetic resonance data after training.
In step 1), the generated simulated high definition diffusion magnetic resonance amplitude map may be generated by a diffusion tensor physical model:
(diffusion tensor model) m (b, g) =exp { -bg T Dg}m 0 (8)
Wherein,for diffusion amplitude image with diffusion b value b in diffusion gradient direction g, +.>For a diffusion image without applied diffusion gradient, T is a transposed symbol, D is a diffusion tensor matrix, and the diffusion gradient is represented by acquiring 1 b value of 0s/mm 2 M of (2) 0 And 64 diffusion direction numbers b of 1000s/mm 2 The actual acquired diffusion image of (2) is calculated by a linear fitting algorithm.
Thus, given a diffusion direction g of [0, 1 ] given D is known]And b has a value b of 1000s/mm 2 A diffusion amplitude image m (g= [0, 1) of the target diffusion direction and b value can be generated],b=1000)。
In step 2), the high-order simulated motion phases of each excited diffusion image can be generated by a physical motion model:
wherein the diagonal matrixIs the phase obtained by simulation of the model, the integer x, y E [1,256 ]]Coordinates at the level are selected for the two-dimensional image, i being an imaginary symbol. L=3 is the single highest order in the polynomial model. By using an L-order polynomial phase model, 4 motion phases can be obtained by fitting the motion phases of the measured data through phase unwrapping and phase wrapping operations>The target multi-shot diffusion weighted data to be reconstructed is four shots.
In step 3), the generated simulated diffusion magnetic resonance amplitude map is generatedHigh-order simulation motion phase diagramAnd an acquired multichannel coil sensitivity map +.>Combining according to the following formula to obtain fully sampled network training label data:
wherein,is a two-dimensional Cartesian systemUnder the coordinate system->Or in a non-Cartesian coordinate system>Fourier transform operator of>Is synthesized 8-channel 4-shot fully sampled k-space data as network training tag data.
In step 4), gaussian noise is added to the fully sampled training tag data to obtain noisy k-space data:
wherein,is Gaussian noise with real and imaginary parts meeting the mean value of 0 and the variance of 0.05,is noisy fully sampled k-space data with a signal-to-noise ratio of X GT Calculated for the noiseless reference diagram is 10dB.
In step 5), setting a sampling track of an acquisition sequence of high-definition diffusion data of a target as a four-time excitation staggered plane echo sequence, undersampling noisy k-space data to obtain simulation 8-channel 4-time excitation diffusion magnetic resonance data of motion artifact interference, wherein the simulation 8-channel 4-time excitation diffusion magnetic resonance data is used as input data of network training:
wherein,the simulation multichannel multi-excitation diffusion magnetic resonance data of motion artifact interference are used as input data of network training. Sampling template->The interleaved planar echo sequence (4 shot-iEPI) may be excited four times, as shown in fig. 2 (a).
In step 6), repeating steps 1) to 5) 100000 times, each time setting different parameters g, b, A lm μ, σ. Generating 100000 group pairs of network training input data X inp And full sample training tag data X GT Thereby constructing a physical intelligence based high quality paired high definition diffusion imaging training dataset containing 100000 samples. Fig. 3 (a) illustrates a pair of physically intelligent generated network training tags and input band motion artifact data.
In step 7), the generated high quality paired high definition diffusion imaging training dataset of physical intelligence can be used to train a neural network. A convolutional neural network is designed that contains 5 identical reconstruction modules, each comprising 6 convolutional layers, each comprising 32 convolutional kernels of 3 x 3 size and a layer of linear rectifying activation functions (the sixth layer does not contain a linear rectifying activation function). After training, the convolutional neural network can be used for reconstructing actual measurement 4-time excitation high-definition diffusion imaging data.
The physical intelligent data generation specific scheme can rapidly generate paired high-definition diffusion imaging data with multiple b values and multiple resolutions, breaks through the bottleneck that the existing intelligent high-definition diffusion imaging network depends on actual measured data and is lack of high-quality training labels, and has wide application prospect
Example 2
The abdomen high-definition diffusion data generation and reconstruction network training process based on four-time excitation readout dimension segmentation sampling is shown in the flow chart of fig. 1, and is described in detail as follows:
the embodiment of the invention comprises the following steps:
1) Generating a simulation high-definition diffusion magnetic resonance amplitude diagram by using diffusion physical models such as diffusion indexes, tensors, kurtosis and the like;
2) Generating a high-order simulation motion phase diagram of each excitation diffusion image based on the physical motion model;
3) Combining the generated simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map, and transforming the simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map into k space by utilizing Fourier transformation to obtain fully-sampled network training label data;
4) Adding Gaussian noise into the full-sampling training label data to obtain noisy k-space data;
5) Undersampling noisy k-space data according to a sampling track of an acquisition sequence of high-definition diffusion data of a target to obtain simulated multichannel multi-excitation diffusion magnetic resonance data with motion artifact interference, wherein the simulated multichannel multi-excitation diffusion magnetic resonance data is used as input data of network training;
6) Repeating steps 1) to 5) in a large number to generate a large number of paired network training input data and full-sampling training label data;
7) Training a neural network by using the generated diffusion magnetic resonance data set, wherein the network is used for reconstructing or denoising the high-definition diffusion magnetic resonance data after training.
In step 1), the generated simulated high definition diffusion magnetic resonance amplitude plot may be generated by a diffusion single-index physical model:
(diffusion single exponential model) m (b) =exp { -bdadc } m 0 (13)
Wherein,is a diffusion amplitude image with diffusion b value b, a>For diffusion images without applied diffusion gradients, ADC is an apparent diffusion coefficient matrix obtained by acquiring 1 b value of 0s/mm 2 M of (2) 0 And 3 diffusion directions b have a value of 1000s/mm 2 The actual acquired diffusion image of (2) is calculated by a linear fitting algorithm to obtain the ADC.
Thus, given a spread b value b of 1000s/mm, given that the ADC is known 2 A diffusion amplitude map of the target diffusion b value can be generatedImage m (b=1000).
In step 2), the high-order simulated motion phases of each excited diffusion image can be generated by a physical motion model:
wherein the diagonal matrixIs the phase obtained by simulation of the model, the integer x, y E [1,256 ]]Coordinates on a level are selected for the two-dimensional image, i is an imaginary symbol, and l=3 is the single highest order in the polynomial model. By using an L-order polynomial phase model, 4 motion phases can be obtained by fitting the motion phases of the measured data through phase unwrapping and phase wrapping operations>The target multi-shot diffusion weighted data to be reconstructed is four shots.
In step 3), the generated simulated diffusion magnetic resonance amplitude map is generatedHigh-order simulation motion phase diagramAnd an acquired multichannel coil sensitivity map +.>Combining according to the following formula to obtain fully sampled network training label data:
wherein,is +.>Or in a non-Cartesian coordinate system>Fourier transform operator of>Is synthesized 8-channel 4-shot fully sampled k-space data as network training tag data.
In step 4), gaussian noise is added to the fully sampled training tag data to obtain noisy k-space data:
wherein,is Gaussian noise with real and imaginary parts meeting the mean value of 0 and the variance of 0.05,is noisy fully sampled k-space data with a signal-to-noise ratio (dB) of X GT Calculated as 10 for the noiseless reference map.
In step 5), setting a sampling track of an acquisition sequence of high-definition diffusion data of a target as a four-time excitation staggered plane echo sequence, undersampling noisy k-space data to obtain simulation 8-channel 4-time excitation diffusion magnetic resonance data of motion artifact interference, wherein the simulation 8-channel 4-time excitation diffusion magnetic resonance data is used as input data of network training:
wherein,the simulation multichannel multi-excitation diffusion magnetic resonance data of motion artifact interference are used as input data of network training. Sampling template->The planar echo sequence (4 shot-rsEPI) of the dimension segment can be read for four excitations, as shown in fig. 2 (b).
In step 6), repeating steps 1) to 5) 100000 times, each time setting different parameters b, A lm μ, σ. Generating 100000 group pairs of network training input data X inp And full sample training tag data X GT Thereby constructing a physical intelligence based high quality paired high definition diffusion imaging training dataset containing 100000 samples. Fig. 3 (b) illustrates a pair of physically intelligent generated network training tags and input band motion artifact data.
In step 7), the generated high quality paired high definition diffusion imaging training dataset of physical intelligence can be used to train a neural network. A convolutional neural network is designed that contains 5 identical reconstruction modules, each comprising 6 convolutional layers, each comprising 32 convolutional kernels of 3 x 3 size and a layer of linear rectifying activation functions (the sixth layer does not contain a linear rectifying activation function). After training, the convolutional neural network can be used for reconstructing actual measurement 4-time excitation high-definition diffusion imaging data.
The physical intelligent data generation specific scheme can rapidly generate paired high-definition diffusion imaging data with multiple b values and multiple resolutions, breaks through the bottleneck that the existing intelligent high-definition diffusion imaging network depends on actual measured data and is lack of high-quality training labels, and has wide application prospect
Example 3
The brain diffusion data generation and denoising network training process based on single excitation planar echo sampling is as follows:
the embodiment of the invention comprises the following steps:
1) Generating a simulation high-definition diffusion magnetic resonance amplitude diagram by using diffusion physical models such as diffusion indexes, tensors, kurtosis and the like;
2) Generating a high-order simulation motion phase diagram of each excitation diffusion image based on the physical motion model;
3) Combining the generated simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map, and transforming the simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map into k space by utilizing Fourier transformation to obtain fully-sampled network training label data;
4) Adding Gaussian noise into the full-sampling training label data to obtain noisy k-space data;
5) Undersampling noisy k-space data according to a sampling track of an acquisition sequence of high-definition diffusion data of a target to obtain simulated multichannel multi-excitation diffusion magnetic resonance data with motion artifact interference, wherein the simulated multichannel multi-excitation diffusion magnetic resonance data is used as input data of network training;
6) Repeating steps 1) to 5) in a large number to generate a large number of paired network training input data and full-sampling training label data;
7) Training a neural network by using the generated diffusion magnetic resonance data set, wherein the network is used for reconstructing or denoising the high-definition diffusion magnetic resonance data after training.
In step 1), the generated simulated high definition diffusion magnetic resonance amplitude map may be generated by a diffusion tensor physical model:
(diffusion tensor model) m (b, g) =exp { -bg T Dg}m 0 (8)
Wherein,for diffusion amplitude image with diffusion b value b in diffusion gradient direction g, +.>For a diffusion image without applied diffusion gradient, T is a transposed symbol, D is a diffusion tensor matrix, and the diffusion gradient is represented by acquiring 1 b value of 0s/mm 2 M of (2) 0 And 64 diffusion direction numbers b of 1000s/mm 2 The actual acquired diffusion image of (2) is calculated by a linear fitting algorithm.
Thus, given a diffusion direction g of [0, 1 ] given D is known]And b has a value b of 1000s/mm 2 A diffusion amplitude image m (g= [0, 1) of the target diffusion direction and b value can be generated],b=1000)。
In step 2), the high-order simulated phase of the diffusion image may be generated by a physical model:
wherein the diagonal matrixIs the phase obtained by simulation through the model. Integer x, y E [1,128 ]]Coordinates at the level are selected for the two-dimensional image, i being an imaginary symbol. L=3 is the single highest order in the polynomial model. And fitting the motion phase of the measured data through phase unwrapping and phase crimping operation by using a 3-order polynomial phase model to obtain the phase.
In step 3), the generated simulated diffusion magnetic resonance amplitude map is generatedHigh-order simulation motion phase diagramAnd an acquired multichannel coil sensitivity map +.>Combining according to the following formula to obtain fully sampled network training label data:
wherein,is +.>Or in a non-Cartesian coordinate system>Fourier transform operator of>Is synthesized 8-channel fully sampled k-space data as network training tag data.
In step 4), gaussian noise is added to the fully sampled training tag data to obtain noisy k-space data:
wherein,is Gaussian noise with real and imaginary parts meeting the mean value of 0 and the variance of 0.05,is noisy fully sampled k-space data with a signal-to-noise ratio of X GT Calculated for the noiseless reference diagram is 10dB.
The generated physical intelligent data in this embodiment is not undersampled through k-space, thus skipping step 5).
In step 6), repeating steps 1) to 4) 100000 times, each time setting different parameters b, A lm μ, σ. Generating 100000 group pairs of network training input dataAnd full sample training tag data X GT Thereby constructing a physical intelligence based high quality paired high definition diffusion imaging training dataset containing 100000 samples. Fig. 3 (c) shows a pair of physically intelligent generated noise-free high signal-to-noise ratio network training tags and input noisy data.
In step 7), the generated high quality paired high definition diffusion imaging training dataset of physical intelligence can be used to train a neural network. A convolutional neural network is designed that contains 3 identical denoising modules, each denoising module containing 6 convolutional layers, each convolutional layer containing 32 convolutional kernels of 3 x 3 size and a linear rectification activation function layer (the sixth layer contains no linear rectification activation function). After training, the convolutional neural network can be used for denoising actually measured single-shot diffusion imaging data.
The physical intelligent data generation specific scheme can rapidly generate paired high-definition diffusion imaging data with multiple b values and multiple resolutions, breaks through the bottleneck that the existing intelligent high-definition diffusion imaging network depends on actual measurement data and is lack of high-quality training labels, and has wide application prospects.
Reference is made to:
[1]V.Baliyan et al.,“Diffusion weighted imaging:technique and applications,”World Journal of Radiology,8,785,2016.
[2]H.An,X.Ma,Z.Pan,H.Guo,E.Y.P.Lee,“Qualitative and quantitative comparison of image quality between single-shot echo-planar and interleaved multi-shot echo-planar diffusion-weighted imaging in female pelvis,”European Radiology,30,1876-1884,2020.
[3]A.W.Anderson,J.C.Gore,“Analysis and correction of motion artifacts in diffusion weighted imaging,”Magnetic Resonance in Medicine,32,379-387,1994.
[4]Aggarwal.H.K.,M.Mani,M.Jacob,“MoDL-MUSSELS:Model-based deep learning for multi-shot sensitivity-encoded diffusion MRI”,IEEE Transactions on Medical Imaging,39,1268-1277,2019.
[5]C.Qian et al.,“A paired phase and magnitude reconstruction for advanced diffusion-weighted imaging,”IEEE Transactions on Biomedical Engineering,DOI:10.1109/TBME.2023.3288031,2023.
[6]F.Wang et al.,“Multiple b-value model-based residual network(MORN)for accelerated high-resolutiondiffusion-weighted imaging”,IEEE Journal of Biomedical and Health Informatics,26,4575-4586,2022.
[7]Q.Yang,Z.Wang,K.Guo,C.Cai,and X.Qu,“Physics-driven synthetic data learning for biomedical magnetic resonance:The imaging physics based data synthesis paradigm for artificial intelligence,”IEEE Signal Processing Magazine,40,129-140,2023.
[8]C.Qian et al.,“Physics-informed deep diffusion reconstruction:Break the bottleneck of training data in artificial intelligence”,arXiv:2210.11388,2023.

Claims (9)

1. the multi-part physical intelligent high-definition diffusion magnetic resonance data generation method is characterized by comprising the following steps of:
1) Generating a simulation high-definition diffusion magnetic resonance amplitude diagram by using a diffusion index, tensor and kurtosis diffusion physical model;
2) Generating a high-order simulation motion phase diagram of each excitation diffusion image based on the physical motion model;
3) Combining the generated simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map, and transforming the simulation high-definition diffusion magnetic resonance amplitude diagram, the high-order simulation motion phase diagram and the acquired multichannel coil sensitivity map into k space by utilizing Fourier transformation to obtain fully-sampled network training label data;
4) Adding Gaussian noise into the full-sampling training label data to obtain noisy k-space data;
5) Undersampling noisy k-space data according to a sampling track of an acquisition sequence of high-definition diffusion data of a target to obtain simulated multichannel multi-excitation diffusion magnetic resonance data with motion artifact interference, wherein the simulated multichannel multi-excitation diffusion magnetic resonance data is used as input data of network training;
6) Repeating steps 1) to 5) in a large number to generate a large number of paired network training input data and full-sampling training label data;
7) Training a neural network by using the generated diffusion magnetic resonance data set, wherein the network is used for reconstructing or denoising the high-definition diffusion magnetic resonance data after training.
2. The method for generating multi-site physical intelligent high-definition diffusion magnetic resonance data according to claim 1, wherein in step 1), the generated simulated high-definition diffusion magnetic resonance amplitude map is generated by a diffusion index, tensor and kurtosis diffusion physical model:
diffusion single-index model: m (b) =exp { -bdadc } m 0 (1)
Wherein,for diffusion magnitude image with diffusion b value b, < ->For a diffusion image with no diffusion gradient applied, ADC is an apparent diffusion coefficient matrix;
diffusion tensor model: m (b, g) =exp { -bg T Dg}m 0 (2)
Wherein,for diffusion amplitude image with diffusion b value b in diffusion gradient direction g, +.>For a diffusion image to which a diffusion gradient is not applied, g represents a unit vector of a diffusion gradient direction, T is a transpose symbol, and D is a diffusion tensor matrix;
diffusion kurtosis model:
wherein,for diffusion amplitude image with diffusion b value b in diffusion gradient direction g, +.>For a diffusion image to which a diffusion gradient is not applied, g represents a unit vector of a diffusion gradient direction, D is a diffusion tensor matrix, and K is a diffusion kurtosis matrix.
3. The method for generating the multi-part physical intelligent high-definition diffusion magnetic resonance data according to claim 2, wherein constants of ADC, D and K in a diffusion single-index, tensor and kurtosis physical model with tissue diffusion information are calculated by acquiring actual diffusion images with enough diffusion b values and diffusion direction numbers through algorithms such as linear fitting;
given the diffusion direction g and b values b, a diffusion magnitude image m of the target diffusion direction and b values is generated, given the ADC, D, K constants are known.
4. The multi-site physical intelligent high definition diffusion magnetic resonance data generating method as claimed in claim 1, wherein in step 2), the high order simulation motion phases of each excitation diffusion image are generated by a physical motion model:
wherein the diagonal matrixIs the phase obtained by simulation of the model, N and M are the lengths of the frequency code and the phase code of the image, x and y are the coordinates on the selected layer of the two-dimensional image, i is the imaginary symbol, L is the highest order of the single expressions in the polynomial model, M and L-M are the powers of the single expressions x and y in the current first order polynomial, A lm Is the corresponding item x m y l-m Coefficients of (2); fitting the motion phases of the measured data by phase unwrapping and phase crimping operations using an L-th order polynomial phase model to obtain J motion phases +.>J is the excitation times of the multi-excitation diffusion weighted data to be reconstructed; then according to the distribution rule of polynomial coefficients in the L-order polynomial phase model, a large number of polynomial coefficients meeting the distribution rule are obtained, and the groupForming a simulation phase set; the motion conditions of different parts are different, the brain and the prostate part are approximately modeled as rigid motion, and a motion model with L=3 is used for simulating motion phases; the abdominal liver and pancreas regions have more complex elastic motions, and motion models of l=7 or higher order are used to approximate simulated motion phases.
5. The method for generating multi-region physical intelligent high-definition diffusion magnetic resonance data as claimed in claim 1, wherein in step 3), the generated simulated high-definition diffusion magnetic resonance amplitude map is generatedHigh-order simulation motion phase diagram->And an acquired multichannel coil sensitivity map +.>Combining according to the following formula to obtain fully sampled network training label data:
wherein,is +.>Or in a non-Cartesian coordinate system>Fourier transform operator of>Is synthesized H channel J-time excited full-sampling k-space data as network training label data.
6. The method for generating multi-part physical intelligent high-definition diffusion magnetic resonance data according to claim 1, wherein in step 4), gaussian noise is added to the fully sampled training tag data to obtain noisy k-space data as follows:
wherein,is Gaussian noise with real and imaginary parts satisfying mean value mu and variance sigma, < >>Is noisy fully sampled k-space data with a signal-to-noise ratio (dB) of X GT And calculating to obtain the noiseless reference diagram.
7. The method for generating multi-part physical intelligent high-definition diffusion magnetic resonance data according to claim 1, wherein in step 5), the noisy k-space data is undersampled according to a sampling track of an acquisition sequence of target high-definition diffusion data to obtain simulated multi-channel multi-excitation diffusion magnetic resonance data with motion artifact interference, and the simulated multi-channel multi-excitation diffusion magnetic resonance data is used as input data of network training:
wherein,is simulated multichannel multi-excitation diffusion magnetic resonance data of motion artifact interference, is taken as input data of network training, and is sampledForm->Sampling tracks for multiple multi-excitation diffusion sequences in Cartesian coordinate systemSampling template->Selecting a multi-excitation staggered plane echo sequence, and multi-excitation reading-out dimension segmentation plane echo sequence; in the case of a non-Cartesian coordinate system +.>Sampling template->The multi-excitation screw sampling sequence and the multi-excitation screw sampling sequence are selected, and the excitation times are set to J times.
8. The method for generating multi-part physical intelligent high definition diffusion magnetic resonance data as claimed in claim 1, wherein in step 6), repeating steps 1) to 5) K times generates K component pairs of network training input data X inp And full sample training tag data X GT Thereby constructing a high-quality paired high-definition diffusion imaging training data set based on physical intelligence and containing K samples.
9. The multi-site physical intelligent high-definition diffusion magnetic resonance data generation method of claim 1, wherein in step 7), the generated diffusion magnetic resonance data set is used for training a neural network, and after training, the network is used for reconstructing or denoising the high-definition diffusion magnetic resonance data.
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