Echo time-dependent magnetic resonance diffusion imaging signal generation method and apparatus, computing device and medium

Abstract

An echo time-dependent magnetic resonance diffusion imaging signal generation method and apparatus. The method comprises: acquiring magnetic resonance non-diffusion-weighted images acquired using a plurality of echo times and magnetic resonance multiple-b-value diffusion-weighted images acquired using a single echo time (S110); on the basis of the non-diffusion-weighted images and quantitative T2 values of multiple water components in human tissues, calculating voxel-by-voxel non-T2 value-weighted magnetic resonance diffusion signals corresponding to the multiple water components in the human tissues (S120); on the basis of the multi-b-value diffusion-weighted images, the magnetic resonance diffusion signals, and the quantitative T2 values, calculating voxel-by-voxel diffusion coefficients corresponding to the multiple water components in the human tissues (S130); and, on the basis of the multi-b-value diffusion-weighted images, the magnetic resonance diffusion signals, the quantitative T2 values and the diffusion coefficients, calculating voxel-by-voxel magnetic resonance diffusion imaging signals acquired using any echo time (S140).

Description

Echo time-dependent magnetic resonance diffusion imaging signal generation method, device, computing device and medium

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 202311521346.1, filed on November 15, 2023, entitled “A method and device for generating echo time-dependent magnetic resonance diffusion imaging signals,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application belongs to the field of medical imaging and processing, and specifically relates to a method, apparatus, computing device and medium for generating an echo time-dependent magnetic resonance diffusion imaging signal. Background Art

[0004] Magnetic resonance imaging is a non-invasive in vivo medical imaging method for the human body, and is widely used in clinical medicine and medical research. The principle of magnetic resonance imaging is that hydrogen atoms generate magnetic moments when excited by radio frequency pulses of fixed frequency in a constant magnetic field. The magnetization intensity gradually weakens according to a certain T1 (longitudinal relaxation time) and T2 (transverse relaxation time). Then, at a certain TE (Echo Time), the magnetic resonance signal is acquired for imaging. Diffusion magnetic resonance imaging, referred to as diffusion imaging, is an imaging method in magnetic resonance imaging. By applying paired diffusion gradients within the echo time, the directional characteristics of the diffusion movement of water molecules in the cellular environment can be collected, thereby measuring the microenvironmental structure of the water molecules. The measurement method of diffusion imaging has been widely used in analyzing the structure of the human nervous system and in diagnosing diseases of the brain, kidneys and other parts of the body.

[0005] Diffusion imaging uses specific diffusion sequences to acquire diffusion signals from human tissue. Through post-processing and calculation, the microstructural characteristics of the cellular environment can be measured. On clinical magnetic resonance imaging devices, images are typically acquired using a spin-echo-based echo-planar imaging sequence. By adjusting numerous parameters within the sequence, such as the echo time, diffusion b-value, and diffusion gradient direction, the desired diffusion-weighted image is obtained. In the acquired image, the brightness of a pixel represents the signal within a rectangular voxel. The size of a single voxel is typically hundreds or thousands of times that of a human cell, so each signal point in the diffusion image represents the sum of the signals of all water molecules within the voxel. To measure the microstructure of the cellular environment in which water molecules reside, the diffusion signal needs to be post-processed and modeled using a corresponding diffusion model. Currently, models such as Diffusion Tensor Imaging (DTI), Diffusion Kurtosis Imaging (DKI), and Neurite Orientation Dispersion and Density Imaging (NODDI) can be used to obtain quantitative model parameters such as average diffusion coefficient, anisotropy fraction, neurite fraction, free water fraction, and directional dispersion to describe various characteristics of the microenvironment.

[0006] In these diffusion models, the T2 of all water molecules within a single voxel is considered to be a uniform value. However, the calculated model parameters are dependent on TE. When imaging is performed using different magnetic resonance imaging devices and different acquisition strategies, the parameter results acquired and processed at different TEs will show measurement deviations. The main reason for this is that the T2 of water molecules in different cellular environments is different, resulting in the contribution of each component to the total signal in the acquired signal varying with TE. Generally speaking, water molecules in the cellular environment of human tissues can be divided into intracellular water molecules, extracellular water molecules, and free water molecules. These three components are distributed in different proportions in different tissues of the human body. Studies have shown that the T2 of these three components is different. Therefore, in the signal acquired using a certain TE, the proportion of the three components varies according to the ratio of TE to their respective T2.

[0007] Summary of the Invention

[0008] According to various embodiments of the present application, a method, apparatus, computing device, and medium for generating an echo time-dependent magnetic resonance diffusion imaging signal are provided.

[0009] An embodiment of the present application provides a method for generating an echo time-dependent magnetic resonance diffusion imaging signal, comprising the following steps:

[0010] acquiring magnetic resonance non-diffusion-weighted images acquired using multiple echo times and magnetic resonance multi-b-value diffusion-weighted images acquired using a single echo time;

[0011] Calculating, voxel by voxel, magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​corresponding to the various water components in the human tissue according to the non-diffusion-weighted magnetic resonance image and the transverse relaxation time values ​​of the various water components in the human tissue;

[0012] Calculating diffusion coefficients corresponding to various water components in human tissue voxel by voxel based on the magnetic resonance multi-b-value diffusion-weighted image, the magnetic resonance diffusion signal, and the transverse relaxation time value;

[0013] A magnetic resonance diffusion imaging signal acquired using any echo time is generated by voxel-by-voxel calculation based on the magnetic resonance multi-b-value diffusion weighted image, the magnetic resonance diffusion signal, the transverse relaxation time value, and the diffusion coefficient.

[0014] Optionally, when acquiring non-diffusion-weighted MRI images and multi-b-value diffusion-weighted MRI images, the same MRI diffusion imaging sequence is used. Except for two MRI sequence parameters, namely, echo time or diffusion b-value, which are set to multiple values ​​within a certain range, other MRI sequence parameters are set to be consistent. Specifically, when acquiring non-diffusion-weighted MRI images, the diffusion b-value is set to zero and at least two echo times are set; when acquiring multi-b-value diffusion-weighted MRI images, the echo time is set to a single fixed value and at least two diffusion b-values ​​are set.

[0015] Optionally, the multiple water components in human tissue include two categories, one is that there are two water components in human tissue, including intracellular water and extracellular water; the other is that there are three water components in human tissue, including intracellular water, extracellular water and free water.

[0016] Optionally, when the multiple water components in human tissue include intracellular water and extracellular water, the following formula (1) is used to calculate the magnetic resonance diffusion signal without transverse relaxation time value weighting on a voxel-by-voxel basis:

[0017] When the human body contains multiple water components including intracellular water, extracellular water and free water, the following formula (2) is used to calculate the magnetic resonance diffusion signal without transverse relaxation time value weighting on a voxel-by-voxel basis:

[0018] Wherein, S0(TE) is the signal of the non-diffusion-weighted magnetic resonance image acquired at the echo time TE, as well as are the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively. as well as are the transverse relaxation times of intracellular water, extracellular water, and free water, respectively.

[0019] Optionally, when the multiple water components in human tissue include intracellular water and extracellular water, the diffusion coefficients corresponding to the multiple water components in human tissue are calculated voxel by voxel using the following formula (3):

[0020] When the multiple water components in human tissue include intracellular water, extracellular water, and free water, the diffusion coefficients corresponding to the multiple water components in human tissue are calculated voxel by voxel using the following formula (4);

[0021] Where S(b,TE0) is the signal of the magnetic resonance multi-b value diffusion weighted image acquired at a single echo time TE0, D in 、 D ex and D iso are the diffusion coefficients of intracellular water, extracellular water, and free water, respectively. as well as are the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively. as well as are the transverse relaxation times of intracellular water, extracellular water, and free water, respectively, and b is the diffusion b value.

[0022] Optionally, when calculating the diffusion coefficient, a fitting calculation is performed once in the vector direction of each diffusion weighted gradient for the signal of the magnetic resonance multi-b-value diffusion weighted image used.

[0023] Optionally, when the multiple water components in human tissue include intracellular water and extracellular water, the following formula (5) is used to calculate and generate the magnetic resonance diffusion imaging signal acquired using any echo time on a voxel-by-voxel basis:

[0024] When the human body contains multiple water components including intracellular water, extracellular water and free water, the following formula (6) is used to calculate the magnetic resonance diffusion imaging signal collected at any echo time on a voxel-by-voxel basis:

[0025] Where S(b,TE0) is the signal of the MRI multi-b-value diffusion-weighted image acquired at a single echo time TE0, ΔTE is the difference between the echo time of the generated MRI diffusion imaging signal and the single echo time value TE0, TE0+ΔTE is set to any positive value starting from zero, S ′ (b, TE0+ΔTE) is the generated magnetic resonance diffusion imaging signal, as well as are the transverse relaxation times of intracellular water, extracellular water and free water, respectively. and are the magnetic resonance diffusion signals weighted by the transverse relaxation time values ​​of extracellular water and free water, respectively. ex and D iso are the diffusion coefficients of extracellular water and free water, respectively, and b is the diffusion b value.

[0026] In a second aspect, the present application provides an echo time-dependent magnetic resonance diffusion imaging signal generation device, comprising an image acquisition module, a multi-component diffusion signal calculation module, a multi-component diffusion coefficient calculation module, and a diffusion imaging signal generation module.

[0027] The image acquisition module is used to acquire a magnetic resonance non-diffusion-weighted image acquired using multiple echo times and a magnetic resonance multi-b-value diffusion-weighted image acquired using a single echo time;

[0028] The multi-component diffusion signal calculation module is used to calculate the magnetic resonance diffusion signal weighted by the non-transverse relaxation time values ​​corresponding to the multiple water components in the human tissue on a voxel-by-voxel basis according to the magnetic resonance diffusion-weighted non-image and the transverse relaxation time values ​​of the multiple water components in the human tissue;

[0029] The multi-component diffusion coefficient calculation module is used to calculate the diffusion coefficients corresponding to multiple water components in human tissue voxel by voxel based on the magnetic resonance multi-b-value diffusion-weighted image, the magnetic resonance diffusion signal and the transverse relaxation time value;

[0030] The diffusion imaging signal generation module is used to calculate and generate a magnetic resonance diffusion imaging signal acquired using any echo time on a voxel-by-voxel basis based on the magnetic resonance multi-b-value diffusion weighted image, the magnetic resonance diffusion signal, the transverse relaxation time value, and the diffusion coefficient.

[0031] In a third aspect, the present application also provides a computing device comprising a memory and one or more processors, wherein the memory stores executable code, and when the one or more processors execute the executable code, they are used to implement the above-mentioned echo time-dependent magnetic resonance diffusion imaging signal generation method.

[0032] In a fourth aspect, the present application further provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the above-mentioned echo time-dependent magnetic resonance diffusion imaging signal generation method.

[0033] Compared with the related art, the present application has the following beneficial effects:

[0034] The calculation of various existing diffusion model coefficients is affected by the inconsistency of echo times in sequence parameters, resulting in a certain degree of calculation deviation in different imaging devices and acquisition strategies. This application uses a multi-component hypothesis to set different relaxation time and diffusion coefficient values ​​for each type of water molecule in the cellular environment. The collected magnetic resonance diffusion-weighted signal is decomposed and reconstructed. The reconstructed signal fully preserves the cellular physiological information in the original signal while avoiding the measurement deviation of the diffusion model coefficient caused by inconsistent echo times.

[0035] This application performs voxel-by-voxel reconstruction of the collected original diffusion signal to generate a new signal, which is not limited by the resolution of the diffusion image and the number of diffusion directions. The current diffusion imaging sequences in clinical magnetic resonance imaging can all collect the original diffusion imaging data required in this application and reconstruct it using the method in this application, which has high clinical practicality.

[0036] The diffusion-weighted imaging signal generation method proposed in this application achieves a reconstructed image that is identical in size and dimension to the original image, while also maintaining the same diffusion direction and b-value. Therefore, any diffusion model that can be used to process the original image can also be used to process the reconstructed image, providing flexibility in application.

[0037] The details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] FIG1 is a flow chart of a method for generating an echo time-dependent magnetic resonance diffusion imaging signal provided by an embodiment.

[0040] FIG2 is a schematic diagram of hypothetical classification of various water components in human tissue provided by an embodiment.

[0041] FIG3 is a flow chart of an example of a method for generating magnetic resonance diffusion imaging signals provided by an embodiment.

[0042] FIG4 is a schematic structural diagram of an echo time-dependent magnetic resonance diffusion imaging signal generating device provided by an embodiment.

[0043] FIG5 is a schematic diagram of the structure of a computing device provided in an embodiment. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and do not limit the scope of protection of this application.

[0045] The inventive concept of the present application is as follows: in order to eliminate the influence of different TE on the diffusion model coefficient, it is necessary to perform multi-component decomposition on the acquired original diffusion signal, extract the resolvable initial signal components therefrom, and reconstruct and generate a diffusion-weighted signal under any consistent TE to prevent deviations in the post-processing calculation of the diffusion model, thereby improving the accuracy of the model coefficient measurement. Specifically, using the assumption based on the multi-component water model of human tissue, after performing multi-component decomposition on the original signal in the magnetic resonance diffusion image, a non-T2-weighted magnetic resonance diffusion signal and the corresponding diffusion coefficient are reconstructed to generate a magnetic resonance diffusion imaging signal acquired at any echo time.

[0046] Based on the inventive concept, as shown in FIG1 , an embodiment provides a method for generating an echo time-dependent magnetic resonance diffusion imaging signal, comprising the following steps:

[0047] S110 , acquiring a non-diffusion-weighted magnetic resonance image acquired using multiple echo times and a multi-b-value diffusion-weighted magnetic resonance image acquired using a single echo time.

[0048] In the embodiment, when acquiring non-diffusion-weighted MRI images and multi-b-value diffusion-weighted MRI images, the same MRI diffusion imaging sequence is used. Except for two MRI sequence parameters, echo time or diffusion b-value, which are set to multiple values ​​within a certain range, the remaining MRI sequence parameters are set to be consistent.

[0049] When acquiring MRI multi-b-value diffusion-weighted images using a single echo time, the echo time in the imaging sequence is set to the minimum value adjustable within the MRI scanner, and the diffusion b-value is set to an intermediate value greater than zero but not exceeding the maximum value achievable by the MRI scanner, with at least two diffusion b-values ​​set in total.

[0050] When acquiring magnetic resonance diffusion-free weighted images at multiple echo times, the echo time is set starting from the minimum value adjustable in the magnetic resonance scanner, and one echo time is set each time a fixed interval value is added, with a total of at least two echo times set. The diffusion b-value is set to zero, and a set of diffusion-free weighted images is acquired at each echo time, and the acquisition can be repeated.

[0051] S120 , calculating, voxel by voxel, magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​corresponding to the various water components in the human tissue according to the non-diffusion weighted magnetic resonance image and the transverse relaxation time values ​​of the various water components in the human tissue.

[0052] In this embodiment, as shown in FIG2 , the assumptions regarding the multiple water components within human tissue are categorized into two types: one assuming that human tissue contains two water components, including intracellular water and extracellular water; and the other assuming that human tissue contains three water components, including intracellular water, extracellular water, and free water. Under these two classification assumptions, the quantitative T2 value, non-T2-weighted MRI diffusion signal, and diffusion coefficient of each water component are different.

[0053] When the human body contains multiple water components including intracellular water and extracellular water, the following formula (1) is used to calculate the magnetic resonance diffusion signal without transverse relaxation time value weighting on a voxel-by-voxel basis:

[0054] When the human body contains multiple water components including intracellular water, extracellular water and free water, the following formula (2) is used to calculate the magnetic resonance diffusion signal without transverse relaxation time value weighting on a voxel-by-voxel basis:

[0055] Wherein, S0(TE) is the signal of the non-diffusion-weighted magnetic resonance image acquired at the echo time TE, as well as are the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively. as well as are the transverse relaxation times of intracellular water, extracellular water, and free water, respectively.

[0056] S130 , calculating diffusion coefficients corresponding to various water components in human tissue voxel by voxel based on the magnetic resonance multi-b-value diffusion-weighted image, the magnetic resonance diffusion signal, and the transverse relaxation time value.

[0057] In the embodiment, the diffusion coefficients corresponding to various water components in human tissue are calculated based on two assumptions, specifically including:

[0058] When the multiple water components in human tissue include intracellular water and extracellular water, the diffusion coefficients corresponding to the multiple water components in human tissue are calculated voxel by voxel using the following formula (3):

[0059] When the multiple water components in human tissue include intracellular water, extracellular water, and free water, the diffusion coefficients corresponding to the multiple water components in human tissue are calculated voxel by voxel using the following formula (4);

[0060] Where S(b,TE0) is the signal of the magnetic resonance multi-b value diffusion weighted image acquired at a single echo time TE0, D in 、D ex and D isoare the diffusion coefficients of intracellular water, extracellular water, and free water, respectively. as well as are the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively. as well as are the transverse relaxation times of intracellular water, extracellular water, and free water, respectively, and b is the diffusion b value.

[0061] In the embodiment, when calculating the diffusion coefficient, a fitting calculation is performed once in each diffusion weighting gradient vector direction for the signal of the magnetic resonance multi-b-value diffusion weighted image used.

[0062] S140 , generating a magnetic resonance diffusion imaging signal acquired using any echo time by calculating voxel by voxel based on the magnetic resonance multi-b-value diffusion weighted image, the magnetic resonance diffusion signal, the transverse relaxation time value, and the diffusion coefficient.

[0063] In the embodiment, when calculating and generating the magnetic resonance diffusion imaging signal acquired using any echo time, the calculation is also based on two assumptions, specifically including:

[0064] When there are multiple water components in human tissue, including intracellular water and extracellular water, the following formula (5) is used to calculate the magnetic resonance diffusion imaging signal collected using any echo time on a voxel-by-voxel basis:

[0065] When the human tissue contains multiple water components including intracellular water, extracellular water and free water, the following formula (6) is used to calculate the magnetic resonance diffusion imaging signal collected using any echo time on a voxel-by-voxel basis:

[0066] Where S(b,TE0) is the signal of the MRI multi-b-value diffusion-weighted image acquired at a single echo time TE0, ΔTE is the difference between the echo time of the generated MRI diffusion imaging signal and the single echo time value TE0, TE0+ΔTE is set to any positive value starting from zero, S ′ (b, TE0+ΔTE) is the generated magnetic resonance diffusion imaging signal, as well as are the transverse relaxation times of intracellular water, extracellular water and free water, respectively. and are the magnetic resonance diffusion signals weighted by the transverse relaxation time values ​​of extracellular water and free water, respectively. ex and D iso are the diffusion coefficients of extracellular water and free water, respectively, and b is the diffusion b value.

[0067] It should be emphasized that the calculation of the non-T2-weighted MRI diffusion signal in S120, the fitting of the diffusion coefficient in S130, and the generation of the MRI diffusion imaging signal in S140 all use a pixel-by-pixel calculation method. That is, any one or a group of pixels extracted from the complete image are applicable to the calculation of the echo time-dependent MRI diffusion imaging signal generation.

[0068] The magnetic resonance diffusion imaging signal generated by S140 through S110 - S140 , and the multi-echo time magnetic resonance non-diffusion weighted image and the magnetic resonance multi-b-value diffusion weighted image acquired in the magnetic resonance scanner of S110 are from the same individual.

[0069] Based on the echo time-dependent magnetic resonance diffusion imaging signal generation method provided in the above embodiment, the embodiment further provides a specific experimental example, as shown in FIG3 , including the following steps:

[0070] S310, magnetic resonance diffusion imaging image acquisition.

[0071] The human brain was imaged using a spin-echo-based echo-planar imaging diffusion sequence on any clinical MRI scanner. Non-diffusion-weighted MRI images were acquired with three or more echo times, and multi-b-value diffusion-weighted MRI images were acquired with a single echo time. If the MRI scanner's sequence parameters permitted, additional non-diffusion-weighted images with inverse phase encoding were acquired to facilitate preprocessing correction.

[0072] S320, preprocessing of magnetic resonance diffusion imaging images.

[0073] All acquired MRI diffusion imaging images were converted from the Dicom image format to the NIfTI format, commonly used in neuroimaging processing, using dcm2niix software. Preprocessing then took place using MRtrix3 and the FSL software package. The preprocessing process included PCA noise reduction, Gibbs ripple artifact removal, main magnetic field distortion estimation and correction, eddy current distortion and head motion correction, and Rician background noise removal. For main magnetic field distortion estimation and correction, if the S310 acquired reverse phase-encoded images, main magnetic field distortion estimation and correction were performed; otherwise, no main magnetic field distortion estimation and correction were performed. Four-dimensional diffusion-weighted images were obtained after preprocessing, with the first three dimensions representing the spatial dimensions and the fourth dimension representing the diffusion-weighted gradient dimension.

[0074] S330, Modeling and fitting of multi-component signals.

[0075] The preprocessed diffusion imaging image is processed in step S120 using the non-diffusion-weighted MRI images from multiple echo times to calculate, on a voxel-by-voxel basis, the non-T2-weighted MRI diffusion signals corresponding to various water components. The quantitative T2 values ​​for various water components in human tissue can be set according to reference values ​​in the literature, such as, under the assumption of a three-component water classification: intracellular water T2 is 90 ms, extracellular water T2 is 60 ms, and free water T2 is 3000 ms. Subsequently, in step S130, the diffusion coefficients corresponding to the various water components are calculated on a voxel-by-voxel basis using the diffusion-weighted MRI images from a single echo time and the non-T2-weighted MRI diffusion signals from step S120, traversing all voxels within the brain. The assumptions for the various water components must be consistent in both step S120 and step S130, i.e., consistent assumptions for two or three water components.

[0076] S340 , generating an echo time-dependent magnetic resonance diffusion image signal.

[0077] The magnetic resonance diffusion-weighted image of a single echo time obtained by S330, the non-T2-weighted magnetic resonance diffusion signals of various water components in human tissue, the diffusion coefficients of various water components in human tissue, and the quantitative T2 values ​​of various water components in human tissue are calculated and generated voxel by voxel through S140 to generate the magnetic resonance diffusion imaging signal of any echo time. After traversing all voxels, a four-dimensional diffusion-weighted image identical to the preprocessed image matrix is ​​generated.

[0078] In general, the embodiments provide a method for generating an echo time-dependent magnetic resonance diffusion imaging signal, which can decompose and reconstruct the original magnetic resonance diffusion signal into multiple components. While fully preserving the physiological information of the original signal, the non-T2-weighted magnetic resonance diffusion signal and diffusion coefficient corresponding to the multiple components are extracted, thereby generating a diffusion-weighted signal under any TE, eliminating the diffusion coefficient measurement deviation caused by inconsistent acquisition echo times in the diffusion model.

[0079] Based on the same inventive concept, as shown in FIG4 , an embodiment further provides an echo time-dependent magnetic resonance diffusion imaging signal generating device 400, comprising an image acquisition module 410, a multi-component diffusion signal calculation module 420, a multi-component diffusion coefficient calculation module 430, and a diffusion imaging signal generating module 440. The image acquisition module 410 is used to acquire a magnetic resonance diffusion-weighted image acquired using multiple echo times and a magnetic resonance multi-b-value diffusion-weighted image acquired using a single echo time; the multi-component diffusion signal calculation module 420 is used to calculate the diffusion coefficient of the magnetic resonance diffusion-weighted image based on the magnetic resonance diffusion-weighted image and the multiple water components in human tissue. The transverse relaxation time value is used to calculate the magnetic resonance diffusion signals corresponding to multiple water components in human tissue on a voxel-by-voxel basis without weighting by the transverse relaxation time value; the multi-component diffusion coefficient calculation module 430 is used to calculate the diffusion coefficients corresponding to multiple water components in human tissue on a voxel-by-voxel basis based on the magnetic resonance multi-b-value diffusion-weighted image, the magnetic resonance diffusion signal, and the transverse relaxation time value; the diffusion imaging signal generation module 440 is used to calculate and generate the magnetic resonance diffusion imaging signal acquired using any echo time on a voxel-by-voxel basis based on the magnetic resonance multi-b-value diffusion-weighted image, the magnetic resonance diffusion signal, the transverse relaxation time value, and the diffusion coefficient.

[0080] It should be noted that the echo-time-dependent MRI signal generation device provided in the above-mentioned embodiments, when generating MRI signals, is illustrated by the division of the above-mentioned functional modules. The above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the terminal or server can be divided into different functional modules to complete all or part of the functions described above. Furthermore, the echo-time-dependent MRI signal generation device provided in the above-mentioned embodiments and the echo-time-dependent MRI signal generation method embodiment are based on the same concept. The specific implementation process is detailed in the echo-time-dependent MRI signal generation method embodiment and will not be further described here.

[0081] Based on the same inventive concept, an embodiment further provides a computing device comprising a memory and one or more processors. The memory stores executable code. When the one or more processors execute the executable code, the device is configured to implement the above-mentioned echo time-dependent magnetic resonance diffusion imaging signal generation method, which specifically includes the following steps:

[0082] S110, acquiring a non-diffusion-weighted magnetic resonance image acquired using multiple echo times and a multi-b-value diffusion-weighted magnetic resonance image acquired using a single echo time;

[0083] S120, calculating, voxel by voxel, magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​corresponding to the various water components in the human tissue based on the non-diffusion weighted magnetic resonance image and the transverse relaxation time values ​​of the various water components in the human tissue;

[0084] S130, calculating diffusion coefficients corresponding to multiple water components in human tissue voxel by voxel based on the magnetic resonance multi-b-value diffusion-weighted image, the magnetic resonance diffusion signal, and the transverse relaxation time value;

[0085] S140 , generating a magnetic resonance diffusion imaging signal acquired using any echo time by calculating voxel by voxel based on the magnetic resonance multi-b-value diffusion weighted image, the magnetic resonance diffusion signal, the transverse relaxation time value, and the diffusion coefficient.

[0086] As shown in FIG5 , the computing device provided in the embodiment includes, at the hardware level, not only a processor and memory, but also hardware required for other services, such as an internal bus, a network interface, and memory. The memory is a non-volatile memory, and the processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to implement the echo time-dependent magnetic resonance diffusion imaging signal generation method described in S110-S140 above. Of course, in addition to software implementation, this application does not exclude other implementation methods, such as logic devices or a combination of software and hardware, etc. In other words, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0087] Based on the same inventive concept, an embodiment further provides a computer-readable storage medium having a program stored thereon. When the program is executed by a processor, the method for generating an echo time-dependent magnetic resonance diffusion imaging signal is implemented, specifically comprising the following steps:

[0088] S110, acquiring a non-diffusion-weighted magnetic resonance image acquired using multiple echo times and a multi-b-value diffusion-weighted magnetic resonance image acquired using a single echo time;

[0089] S120, calculating, voxel by voxel, magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​corresponding to the various water components in the human tissue based on the non-diffusion weighted magnetic resonance image and the transverse relaxation time values ​​of the various water components in the human tissue;

[0090] S130, calculating diffusion coefficients corresponding to multiple water components in human tissue voxel by voxel based on the magnetic resonance multi-b-value diffusion-weighted image, the magnetic resonance diffusion signal, and the transverse relaxation time value;

[0091] S140 , generating a magnetic resonance diffusion imaging signal acquired using any echo time by calculating voxel by voxel based on the magnetic resonance multi-b-value diffusion weighted image, the magnetic resonance diffusion signal, the transverse relaxation time value, and the diffusion coefficient.

[0092] In an embodiment, computer-readable media includes permanent and non-permanent, removable and non-removable media that can be used to store information by any method or technology. The information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include temporary computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0093] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present application. It should be understood that the above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, supplements, and equivalent substitutions made within the scope of the principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for generating an echo time-dependent magnetic resonance diffusion imaging signal, characterized in that: The following steps are involved: Acquiring a non-diffusion-weighted magnetic resonance image acquired using multiple echo times and a multi-b-value diffusion-weighted magnetic resonance image acquired using a single echo time; According to the magnetic resonance diffusion-free weighted image and the transverse relaxation time values ​​of the various water components in the human tissue, the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​corresponding to the various water components in the human tissue are calculated voxel by voxel, including: the various water components in the human tissue include two categories, one category is that there are two water components in the human tissue, including intracellular water and extracellular water; the other category is that there are three water components in the human tissue, including intracellular water, extracellular water and free water; When multiple water components in human tissue include intracellular water and extracellular water, the following formula (1) is used to calculate the magnetic resonance diffusion signal without transverse relaxation time value weighting on a voxel-by-voxel basis: When there are multiple water components in human tissues, including intracellular water, extracellular water and free water, the following formula (2) is used to calculate the magnetic resonance diffusion signal without transverse relaxation time value weighting on a voxel-by-voxel basis: Among them, S0(TE) is the signal of the magnetic resonance diffusion-free weighted image acquired at the echo time TE, as well as are the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively. as well as are the transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively; Calculating diffusion coefficients corresponding to multiple water components in human tissue voxel by voxel according to the magnetic resonance multi-b-value diffusion weighted image, the magnetic resonance diffusion signal and the transverse relaxation time value, including: When the multiple water components in human tissue include intracellular water and extracellular water, the diffusion coefficients corresponding to the multiple water components in human tissue are calculated voxel by voxel using the following formula (3): When the multiple water components in human tissue include intracellular water, extracellular water and free water, the diffusion coefficients corresponding to the multiple water components in human tissue are calculated voxel by voxel using the following formula (4): Where S(b,TE0) is the signal of the magnetic resonance multi-b value diffusion weighted image acquired at a single echo time TE0, D in , D ex and D iso are the diffusion coefficients of intracellular water, extracellular water and free water, respectively. as well as respectively is the magnetic resonance diffusion signal weighted by the non-transverse relaxation time values ​​of intracellular water, extracellular water and free water, as well as are the transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively, and b is the diffusion b value; The method comprises: generating a magnetic resonance diffusion imaging signal acquired using any echo time by calculating voxel by voxel according to the magnetic resonance multi-b-value diffusion weighted image, the magnetic resonance diffusion signal, the transverse relaxation time value and the diffusion coefficient, comprising: When there are multiple water components in human tissues, including intracellular water and extracellular water, the following formula (5) is used to calculate the magnetic resonance diffusion imaging signal collected using any echo time on a voxel-by-voxel basis: When there are multiple water components in human tissues, including intracellular water, extracellular water, and free water, the following formula (6) is used to calculate the magnetic resonance diffusion imaging signal collected using any echo time on a voxel-by-voxel basis: Wherein, S(b,TE0) is the signal of the magnetic resonance multi-b value diffusion weighted image acquired at a single echo time TE0, ΔTE is the difference between the echo time of the generated magnetic resonance diffusion imaging signal and the single echo time value TE0, TE0+ΔTE is set to any positive value starting from zero, and S′(b,TE0+ΔTE) is the generated magnetic resonance diffusion imaging signal. as well as are the transverse relaxation times of intracellular water, extracellular water and free water, respectively. and are the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​of extracellular water and free water, respectively. ex and D iso are the diffusion coefficients of extracellular water and free water, respectively, and b is the diffusion b value.

2. The method for generating echo time-dependent magnetic resonance diffusion imaging signals according to claim 1, wherein: When acquiring MRI non-diffusion-weighted images and MRI multi-b-value diffusion-weighted images, the same MRI diffusion imaging sequence is used. Except for the two MRI sequence parameters of echo time or diffusion b-value being set to multiple values ​​within a certain range, the other MRI sequence parameters are set to be consistent. Specifically, when acquiring MRI non-diffusion-weighted images, the diffusion b-value is set to zero and the echo time is set to at least two values; when acquiring MRI multi-b-value diffusion-weighted images, the echo time is set to a single fixed value and the diffusion b-value is set to at least two values.

3. The method for generating echo time-dependent magnetic resonance diffusion imaging signals according to claim 1, wherein: When calculating the diffusion coefficient, a fitting calculation is performed once in the vector direction of each diffusion weighted gradient for the signal of the magnetic resonance multi-b-value diffusion weighted image used.

4. An echo time-dependent magnetic resonance diffusion imaging signal generating device, characterized in that: It includes an image acquisition module, a multi-component diffusion signal calculation module, a multi-component diffusion coefficient calculation module, and a diffusion imaging signal generation module. The image acquisition module is used to acquire a magnetic resonance diffusion-free weighted image acquired using multiple echo times and a magnetic resonance diffusion-weighted image acquired using a single echo time; The multi-component diffusion signal calculation module is used to calculate the magnetic resonance diffusion signal weighted by the non-transverse relaxation time value corresponding to the multiple water components in the human tissue voxel by voxel according to the magnetic resonance non-diffusion weighted image and the transverse relaxation time values ​​of the multiple water components in the human tissue, including: the multiple water components in the human tissue include two categories, one category is that the human tissue has two water components, including intracellular water and extracellular water; the other category is that the human tissue has three water components, including intracellular water, extracellular water and free water; When multiple water components in human tissue include intracellular water and extracellular water, the following formula (1) is used to calculate the magnetic resonance diffusion signal without transverse relaxation time value weighting on a voxel-by-voxel basis: When there are multiple water components in human tissues, including intracellular water, extracellular water and free water, the following formula (2) is used to calculate the magnetic resonance diffusion signal without transverse relaxation time value weighting on a voxel-by-voxel basis: Among them, S0(TE) is the signal of the magnetic resonance diffusion-free weighted image acquired at the echo time TE, as well as are the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively. as well as are the transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively; The multi-component diffusion coefficient calculation module is used to calculate the diffusion coefficients corresponding to multiple water components in human tissue voxel by voxel according to the magnetic resonance multi-b-value diffusion weighted image, the magnetic resonance diffusion signal and the transverse relaxation time value, including: When the multiple water components in human tissue include intracellular water and extracellular water, the diffusion coefficients corresponding to the multiple water components in human tissue are calculated voxel by voxel using the following formula (3): When the multiple water components in human tissue include intracellular water, extracellular water and free water, the diffusion coefficients corresponding to the multiple water components in human tissue are calculated voxel by voxel using the following formula (4): Where S(b,TE0) is the signal of the magnetic resonance multi-b value diffusion weighted image acquired at a single echo time TE0, D in , D ex and D iso are the diffusion coefficients of intracellular water, extracellular water and free water, respectively. as well as are the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively. as well as are the transverse relaxation time values ​​of intracellular water, extracellular water and free water, respectively, and b is the diffusion b value; The diffusion imaging signal generation module is used to calculate and generate a magnetic resonance diffusion imaging signal acquired using any echo time on a voxel-by-voxel basis according to the magnetic resonance multi-b-value diffusion weighted image, the magnetic resonance diffusion signal, the transverse relaxation time value, and the diffusion coefficient, including: When there are multiple water components in human tissues, including intracellular water and extracellular water, the following formula (5) is used to calculate the magnetic resonance diffusion imaging signal collected using any echo time on a voxel-by-voxel basis: When there are multiple water components in human tissues, including intracellular water, extracellular water, and free water, the following formula (6) is used to calculate the magnetic resonance diffusion imaging signal collected using any echo time on a voxel-by-voxel basis: Wherein, S(b,TE0) is the signal of the magnetic resonance multi-b value diffusion weighted image acquired at a single echo time TE0, ΔTE is the difference between the echo time of the generated magnetic resonance diffusion imaging signal and the single echo time value TE0, TE0+ΔTE is set to any positive value starting from zero, and S′(b,TE0+ΔTE) is the generated magnetic resonance diffusion imaging signal. as well as are the transverse relaxation times of intracellular water, extracellular water and free water, respectively. and are the magnetic resonance diffusion signals weighted by the non-transverse relaxation time values ​​of extracellular water and free water, respectively. ex and D iso are the diffusion coefficients of extracellular water and free water, respectively, and b is the diffusion b value.

5. A computing device comprising a memory and one or more processors, wherein the memory stores executable code, characterized in that: When the one or more processors execute the executable code, they are used to implement the echo time-dependent magnetic resonance diffusion imaging signal generation method according to any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that: A program is stored thereon, and when the program is executed by a processor, the method for generating an echo time-dependent magnetic resonance diffusion imaging signal according to any one of claims 1 to 3 is implemented.

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