Magnetic resonance imaging method and device and storage medium

Abstract

The invention relates to a magnetic resonance imaging method and device and a storage medium, and the method comprises the steps: scanning a target region through employing a first magnetic resonance sequence, setting a plurality of echo times, and collecting a plurality of spin echo images; recording a plurality of echo times and corresponding dispersion sensitivity coefficients according to the first magnetic resonance sequence; scanning the target area by using the second magnetic resonance sequence to obtain an apparent dispersion coefficient; and according to the plurality of spin echo images, the plurality of echo times, the dispersion sensitivity coefficient and the apparent dispersion coefficient, fitting to obtain a transverse relaxation time constant quantitative image for correcting the dispersion influence. According to the method and the device, the problem of dispersion when a magnetic resonance transverse relaxation time constant quantitative image is obtained through a variable echo time spin echo method in the prior art is solved, and the beneficial effect of effectively improving the quantitative accuracy is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic resonance imaging, and particularly to a method, device and storage medium for magnetic resonance imaging. Background Art

[0002] Magnetic resonance imaging (MRI) technology is a non-invasive diagnostic technology based on the principle of nuclear magnetic resonance. It has no ionizing radiation, can image through any cross-section, and can perform three-dimensional reconstruction to obtain the anatomical and functional structures of tissues and organs, thereby providing diagnostic information for lesions. The longitudinal relaxation time constant (T1) and the transverse relaxation time constant (T2) are the most basic contrast mechanisms in MRI, and the relaxation times of different tissues in the human body are also different. Most clinical conventional sequences are based on the differences in T1 and T2 between different tissues to achieve tissue identification and lesion detection.

[0003] Quantitative magnetic resonance (QMR), compared with qualitative weighted imaging, directly measures parameter values such as T1 and T2 of voxels. This not only has higher sensitivity and specificity for the detection of human pathological tissues, but also greatly reduces the differences in results of different devices. Therefore, it has very important clinical value and research value. Classified according to the quantitative object, QMR is mainly divided into three categories: quantitative imaging of tissue relaxation parameters, quantitative imaging of tissue chemical components, and quantitative imaging of tissue physiology. Among them, the most widely used is quantitative imaging of tissue relaxation parameters, including T1 quantitative maps, T2 quantitative maps, T2* quantitative maps, etc. How to quickly and accurately measure the relaxation time of voxels has always been the goal of magnetic resonance scientists. In particular, T2 quantitative maps have been one of the research hotspots in the field of magnetic resonance imaging in recent years.

[0004] The magnetic resonance transverse relaxation time constant (T2) reflects the specificity of tissues by describing the decay of transverse magnetization of tissues. By measuring the magnetic resonance signal intensities at different echo times and calculating the T2 value from the equation S(t) = Sexp(-t / T2). The most classic existing methods for quantitative imaging of the magnetic resonance transverse relaxation time constant (T2) are the Variable Time of Echo Spin Echo (VTE_SE) method and the Multi-Echo Spin Echo (ME_SE) method. The ME_SE method has a short scanning time, but the signals collected by this method are mixed with stimulated echo signals in addition to spin echo signals. Therefore, the accuracy of the multi-echo spin echo method is often questioned. The signals collected by the variable time of echo spin echo method only contain spin echo components, and the quantitative results are more accurate. It is usually used as the gold standard for quantitative measurement of the magnetic resonance transverse relaxation time constant. However, in this method, the change in echo time will cause different degrees of signal attenuation caused by diffusion, resulting in errors in the quantitative results of the transverse relaxation time constant.

[0005] In the related art, when obtaining a quantitative image of the transverse relaxation time constant of magnetic resonance through the spin echo method with variable echo time, there is a problem of diffusion. Currently, no effective solution has been proposed except for strictly designing the gradient timing. Summary of the Invention

[0006] In this embodiment, a method, device, electronic device, and storage medium for magnetic resonance imaging are provided to solve the problem that diffusion affects the quantitative accuracy when obtaining a quantitative image of the transverse relaxation time constant of magnetic resonance through the spin echo method with variable echo time in the related art.

[0007] In a first aspect, in this embodiment, a method for magnetic resonance imaging is provided. The method for magnetic resonance imaging includes: scanning a target region using a first magnetic resonance sequence, setting multiple echo times, and acquiring multiple spin echo images; recording the multiple echo times and corresponding diffusion sensitivity coefficients according to the first magnetic resonance sequence; scanning the target region using a second magnetic resonance sequence to obtain an apparent diffusion coefficient; and fitting a quantitative image of the transverse relaxation time constant that corrects for diffusion effects based on the multiple spin echo images, the multiple echo times, the diffusion sensitivity coefficients, and the apparent diffusion coefficient.

[0008] In some embodiments, the first magnetic resonance sequence is a spin echo sequence for scanning to obtain the spin echo images; the second magnetic resonance sequence is a magnetic resonance sequence with a diffusion encoding gradient for obtaining the apparent diffusion coefficient of the target tissue.

[0009] In some embodiments, the spin echo sequence is a single echo spin echo pulse sequence.

[0010] In some embodiments, the scanning the target region using the second magnetic resonance sequence to obtain an apparent diffusion coefficient includes: the second magnetic resonance sequence having the same position, image size, and voxel size as the first magnetic resonance sequence; the second magnetic resonance sequence scanning the target region by setting multiple magnetic resonance sequences with the diffusion encoding gradient, fitting to generate a two-dimensional map including the apparent diffusion coefficient, and obtaining the apparent diffusion coefficient according to the two-dimensional map.

[0011] In some of these embodiments, the method of fitting a transverse relaxation time constant quantitative image that corrects for diffusion effects based on the plurality of spin echo images, the plurality of echo times, the diffusion sensitivity coefficient, and the apparent diffusion coefficient includes: obtaining the correspondence between the signal intensity, the transverse magnetization vector, the echo time, the transverse relaxation time constant, the diffusion sensitivity coefficient, and the apparent diffusion coefficient; and fitting, for each voxel, the transverse relaxation time constant quantitative image that corrects for diffusion effects based on the correspondence, the signal intensity, the plurality of echo times, the diffusion sensitivity coefficients corresponding to the plurality of echo times, and the apparent diffusion coefficient.

[0012] In some of these embodiments, obtaining the correspondence between the signal intensity, the transverse magnetization vector, the echo time, the transverse relaxation time constant, the diffusion sensitivity coefficient, and the apparent diffusion coefficient includes: generating a first coefficient based on the exponential function of the ratio of the echo time to the transverse relaxation time constant; generating a second coefficient based on the exponential function of the product of the diffusion sensitivity coefficient and the apparent diffusion coefficient; generating a third coefficient based on the product of the transverse magnetization vector, the first coefficient, and the second coefficient; and generating the correspondence based on the signal intensity and the third coefficient.

[0013] In a second aspect, an apparatus for magnetic resonance imaging is provided in this embodiment. The apparatus for magnetic resonance imaging includes: a first scanning module configured to scan a target region using a first magnetic resonance sequence, set a plurality of echo times, and acquire a plurality of spin echo images; a recording module configured to record the plurality of echo times and corresponding diffusion sensitivity coefficients according to the first magnetic resonance sequence; a second scanning module configured to scan the target region using a second magnetic resonance sequence to obtain an apparent diffusion coefficient; and a fitting module configured to fit a transverse relaxation time constant quantitative image that corrects for diffusion effects based on the plurality of spin echo images, the plurality of echo times, the diffusion sensitivity coefficient, and the apparent diffusion coefficient.

[0014] In a third aspect, an electronic device is provided in this embodiment, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the method for magnetic resonance imaging described in the first aspect above is implemented.

[0015] In a fourth aspect, a storage medium is provided in this embodiment, on which a computer program is stored. When the program is executed by a processor, the method for magnetic resonance imaging described in the first aspect above is implemented.

[0016] Compared with the related art, in a method, apparatus, electronic device, and storage medium for magnetic resonance imaging provided in this embodiment, by using a first magnetic resonance sequence to scan a target region, setting multiple echo times, and acquiring multiple spin echo images; recording multiple echo times and corresponding diffusion sensitivity coefficients according to the first magnetic resonance sequence; using a second magnetic resonance sequence to scan the target region to obtain an apparent diffusion coefficient; and fitting a transverse relaxation time constant quantitative image that corrects the influence of diffusion based on the multiple spin echo images, multiple echo times, diffusion sensitivity coefficients, and apparent diffusion coefficient, the problem of diffusion in the related art when obtaining a magnetic resonance transverse relaxation time constant quantitative image by the spin echo method with variable echo time is solved, and the beneficial effect of effectively improving the quantitative accuracy is achieved.

[0017] 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 concise and understandable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments and descriptions thereof of the present application are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0019] Figure 1 is a hardware structural block diagram of a terminal for executing a method for magnetic resonance imaging according to this embodiment;

[0020] Figure 2 is a flowchart of a method for magnetic resonance imaging according to this embodiment;

[0021] Figure 2-1 is a waveform diagram of a first magnetic resonance sequence according to this embodiment;

[0022] Figure 2-2 is a waveform diagram of another first magnetic resonance sequence according to this embodiment;

[0023] Figure 3 is a flowchart of a method for magnetic resonance imaging according to this preferred embodiment;

[0024] Figure 4 is a structural block diagram of an apparatus for magnetic resonance imaging according to this embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] To more clearly understand the purpose, technical solution, and advantages of the present application, the present application is described and illustrated below with reference to the drawings and embodiments.

[0026] Unless otherwise defined, technical or scientific terms used in this application shall have the ordinary meanings as understood by those of ordinary skill in the technical field to which this application belongs. In this application, words such as "a", "an", "one kind", "the", "these", etc. do not indicate a limitation in quantity, and they can be singular or plural. The terms "including", "containing", "having" and any variants thereof involved in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product or device containing a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent in these processes, methods, products or devices. The terms "connected", "linked", "coupled" and other similar words involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "plurality" involved in this application means two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, and B exists alone. Usually, the character " / " indicates that the objects associated before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific order for the objects.

[0027] The method embodiments provided in this embodiment can be executed on a terminal, a computer or a similar computing device. For example, when running on a terminal, Figure 1 is a hardware structure block diagram of a terminal for executing a magnetic resonance imaging method of this embodiment. As Figure 1 shown, the terminal may include one or more ( Figure 1 only one is shown in the figure) processors 102 and a memory 104 for storing data. Among them, the processor 102 may include, but is not limited to, a processing device such as a microprocessor MCU or a programmable logic device FPGA. The above terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those of ordinary skill in the art can understand that Figure 1 the structure shown is only schematic and does not limit the structure of the above terminal. For example, the terminal may further include more or fewer components than those shown in Figure 1 the figure, or have a different configuration from that shown in Figure 1 the figure.

[0028] The memory 104 can be used to store computer programs, for example, software programs and modules of application software, such as the computer program corresponding to a magnetic resonance imaging method in this embodiment. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, implements the above-mentioned method. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memories. In some instances, the memory 104 may further include a memory remotely disposed relative to the processor 102, and these remote memories can be connected to the terminal through a network. Examples of the above-mentioned network include but are not limited to the Internet, enterprise intranet, local area network, mobile communication network, and combinations thereof.

[0029] The transmission device 106 is used to receive or send data via a network. The above-mentioned network includes the wireless network provided by the communication provider of the terminal. In one instance, the transmission device 106 includes a network adapter (Network Interface Controller, abbreviated as NIC), which can be connected to other network devices through a base station and thus communicate with the Internet. In one instance, the transmission device 106 can be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0030] In the prior art, a magnetic resonance imaging method is provided, and the method includes the following steps:

[0031] By setting different echo times TE, spin echo images with different T2 contrasts can be obtained, and a T2 quantitative image can be obtained by performing data fitting pixel by pixel according to the T2 quantitative formula. Among them, the transverse relaxation time constant quantitative formula is as follows:

[0032]

[0033] Among them, M xy is the transverse magnetization vector, S(TE) is the signal intensity, that is, the spin echo image data collected, and TE is the echo time. However, when changing the TE of the spin echo sequence, the distance between its gradients changes accordingly, resulting in different degrees of diffusion attenuation of the signals collected at different TEs. The transverse relaxation time constant quantitative formula considering the diffusion effect becomes:

[0034]

[0035] Among them, b is the diffusion sensitivity coefficient, which is related to the distribution of gradients in the sequence and varies with TE; D is the apparent diffusion coefficient (ADC), which is an inherent parameter characterizing the level of water molecule movement. In existing magnetic resonance imaging methods, diffusion causes signal attenuation of the acquired echo images to varying degrees, resulting in errors in the finally fitted T2 quantitative images.

[0036] In this embodiment, a magnetic resonance imaging method is provided. Figure 2 It is a flowchart of a magnetic resonance imaging method in this embodiment, as Figure 2 shown, and this process includes the following steps:

[0037] Step S202: Scan the target area using a first magnetic resonance sequence, set multiple echo times, and acquire multiple spin echo images.

[0038] Specifically, the magnetic resonance device sets the first magnetic resonance sequence based on the magnetic resonance scanning protocol. The scanner of the magnetic resonance device scans the target area through the first magnetic resonance sequence. By setting different echo times, multiple spin echo images are acquired, and the multiple spin echo images obtained by scanning are sent to the computer device. Due to different echo times, these spin echo images have different image contrasts. The above-mentioned first magnetic resonance sequence can be a spin echo sequence. The above-mentioned target area can be a certain part of the human body or an organism, such as the brain or the heart, etc.

[0039] In some of these embodiments, the first magnetic resonance sequence is a single echo spin echo sequence, such as Figure 2-1 or Figure 2-2The abscissa represents time and the ordinate represents amplitude. The first row is the radiofrequency pulse part. In the spin echo sequence, its classic structure is 90°-180°. The flip angle of the 180° radiofrequency pulse is twice that of the 90°, indicating that the radiofrequency pulse lasts longer or has a higher voltage. The radiofrequency pulse is one of the most important parts of the magnetic resonance sequence. Without the radiofrequency pulse, it is impossible to generate magnetic resonance signals. Generally, the flip angle is used to reflect the effect of the radiofrequency pulse, such as the 90° radiofrequency pulse and 180° radiofrequency pulse in the figure. The 90° radiofrequency pulse in the figure plays the role of exciting signals, and the 180° radiofrequency pulse plays the role of refocusing signals to generate spin echoes. The second row is the slice selection gradient. Cooperating with the radiofrequency pulse, it can selectively excite a certain slice. Therefore, when the radiofrequency pulse works, the slice selection gradient is generally turned on at the same time. The third row is the phase encoding gradient. In order to spatially locate the signals within the slice, the phase encoding gradient needs to be turned on first to perform phase encoding on the protons. The fourth row is the frequency encoding gradient. After the 180° refocusing pulse, the spin echo signal is generated. While collecting the signal, the frequency encoding gradient is turned on to encode the precession frequency of the signal, and the frequency information of protons at different positions can be obtained. The fifth row is the generation of magnetic resonance signals. After being excited by the 90° radiofrequency pulse, a free induction decay (FID) signal will first be generated in the horizontal direction. Due to the T2 relaxation of the tissue and the inhomogeneity of the main magnetic field, the protons will dephase, resulting in a rapid attenuation of the signal. After the 180° refocusing pulse, waiting for the same amount of time, the proton phases will refocus to generate a spin echo signal. At this time, the frequency encoding gradient is turned on while collecting the magnetic resonance signal, and the obtained data is filled into a phase encoding line of the K-space. Performing an inverse Fourier transform on the K-space data can obtain the spin echo image.

[0040] Step S204: According to the first magnetic resonance sequence, record multiple echo times and corresponding diffusion sensitivity coefficients.

[0041] Specifically, record the multiple different echo times set in step S202. Usually, a change in the echo time is accompanied by a change in the gradient timing, which ultimately leads to a change in the diffusion sensitivity coefficient b value. The b value can be calculated using formula (3):

[0042]

[0043] where γ is the gyromagnetic ratio, which is a constant; G is the amplitude of the gradient; δ is the duration of the gradient; Δ is the interval between gradients. A change in the echo time affects the Δ value, and the corresponding diffusion sensitivity coefficient is calculated and recorded.

[0044] Step S206: Use the second magnetic resonance sequence to scan the target area to obtain the apparent diffusion coefficient.

[0045] Specifically, in the embodiments of the present application, the second magnetic resonance sequence may adopt a magnetic resonance sequence with diffusion encoding gradients, such as an echo-planar imaging diffusion-weighted imaging sequence (EPI-DWI, Echo-Planar Imaging-Diffusion Weighted Imaging). The second magnetic resonance sequence maintains the same geometric position, image size, and voxel size as the first magnetic resonance sequence, scans the same target area to generate an ADC map, and obtains spatially corresponding D values.

[0046] Step S208: According to multiple spin echo images, multiple echo times, diffusion sensitivity coefficients, and apparent diffusion coefficients, fit to obtain a transverse relaxation time constant quantitative image that corrects the influence of diffusion.

[0047] Specifically, according to formula (2), substitute the data of multiple spin echo images, multiple echo times, diffusion sensitivity coefficients, and apparent diffusion coefficients into formula (2), perform optimization processing, fit to obtain the transverse relaxation time constant T2 that minimizes the error, and finally obtain a transverse relaxation time constant quantitative image that corrects the influence of diffusion.

[0048] Through the above steps S202 to S208, by using the first magnetic resonance sequence to scan the target area, setting multiple echo times, and acquiring multiple spin echo images; according to the first magnetic resonance sequence, recording multiple echo times and corresponding diffusion sensitivity coefficients; using the second magnetic resonance sequence to scan the target area based on the same position, image size, and voxel size to obtain the apparent diffusion coefficient; according to multiple spin echo images, multiple echo times, diffusion sensitivity coefficients, and apparent diffusion coefficients, fit to obtain a transverse relaxation time constant quantitative image that corrects the influence of diffusion. By adding a diffusion influence term to the T2 quantitative fitting formula, it is possible to effectively correct the influence caused by diffusion in the spin echo method with variable echo times under any gradient timing conditions that conform to the sequence design.

[0049] In some of these embodiments, the first magnetic resonance sequence is a spin echo sequence for scanning to obtain spin echo images; the second magnetic resonance sequence is a magnetic resonance sequence with diffusion encoding gradients for obtaining the apparent diffusion coefficient of the target tissue.

[0050] In the embodiments of the present application, the first magnetic resonance scanning sequence may be a spin echo sequence, and a 180° pulse is applied once after a 90° radio frequency pulse excitation.

[0051] In some of these embodiments, the spin echo sequence is a single echo spin echo pulse sequence. Among them, the single echo spin echo pulse sequence applies a 180° pulse only once after a 90° radio frequency pulse excitation and acquires one echo, which is the most classic spin echo sequence.

[0052] In some of these embodiments, the magnetic resonance sequence with a diffusion encoding gradient includes an echo-planar diffusion-weighted imaging sequence.

[0053] In some of these embodiments, scanning a target region using a second magnetic resonance sequence to obtain an apparent diffusion coefficient includes: the second magnetic resonance sequence being set with the same position, image size, and voxel size as the first magnetic resonance sequence; the second magnetic resonance sequence scanning the target region through a magnetic resonance sequence with multiple diffusion encoding gradients, fitting to generate a two-dimensional map containing the apparent diffusion coefficient, and obtaining the apparent diffusion coefficient according to the two-dimensional map.

[0054] Specifically, the first magnetic resonance sequence can be a spin-echo sequence, and the second magnetic resonance sequence can be an echo-planar diffusion-weighted imaging sequence. The position of the echo-planar diffusion-weighted imaging sequence is aligned with the position of the spin-echo sequence. The echo-planar diffusion-weighted imaging sequence and the spin-echo sequence have the same voxel size and the same image size. Scanning the target region through a magnetic resonance sequence with multiple diffusion encoding gradients, fitting to generate a two-dimensional map containing the apparent diffusion coefficient. The target region image is obtained by setting multiple b values. The computer device selects the target region image corresponding to the corresponding b value and calculates f(x, y, D). The f(x, y, D) carries known two-dimensional position information, where f(x, y, D) represents the D value at the coordinate point (x, y). Then the computer device can process f(x, y, D) to obtain a two-dimensional spectrum, that is, a coupled spectrum; this two-dimensional spectrum carries all discrete Ds, and for any point in the two-dimensional spectrum, the corresponding D has a corresponding f(x, y, D).

[0055] In some of these embodiments, fitting to obtain a transverse relaxation time constant quantitative image for correcting the diffusion effect according to multiple spin-echo images, multiple echo times, diffusion sensitivity coefficients, and apparent diffusion coefficients includes: obtaining the correspondence between the signal intensity and the transverse magnetization vector, echo time, transverse relaxation time constant, diffusion sensitivity coefficient, and apparent diffusion coefficient; according to the correspondence, signal intensity, multiple echo times, diffusion sensitivity coefficients corresponding to the multiple echo times, and apparent diffusion coefficient, fitting voxel by voxel to obtain a transverse relaxation time constant quantitative image for correcting the diffusion effect.

[0056] In some of these embodiments, obtaining the correspondence between the signal intensity and the transverse magnetization vector, echo time, transverse relaxation time constant, diffusion sensitivity coefficient, and apparent diffusion coefficient includes: generating a first coefficient according to the exponential function of the ratio of the echo time to the transverse relaxation time constant; generating a second coefficient according to the exponential function of the product of the diffusion sensitivity coefficient and the apparent diffusion coefficient; generating a third coefficient according to the product of the transverse magnetization vector, the first coefficient, and the second coefficient; generating the correspondence according to the signal intensity and the third coefficient.

[0057] In an embodiment of the present application, the correspondence between signal intensity and transverse magnetization vector, echo time, transverse relaxation time constant, diffusion sensitivity coefficient, and apparent diffusion coefficient is shown in formula (2). According to the exponential function of the ratio TE / T2 of the echo time TE to the transverse relaxation time constant T2 generate a first coefficient According to the exponential function e of the product bD of the diffusion sensitivity coefficient b and the apparent diffusion coefficient D bD , generate a second coefficient e -bD . According to the product of the transverse magnetization vector M xy , the first coefficient, and the second coefficient, generate a third coefficient. The signal intensity forms an equation relationship with the third coefficient. According to the detected signal intensity and the already known echo time TE, b value, and D value, the transverse magnetization vector and T2 value can be calculated. The transverse relaxation time constant quantitative image is obtained by combining the T2 values of each voxel.

[0058] The following describes and illustrates this embodiment through preferred embodiments.

[0059] Figure 3 is a flowchart of a magnetic resonance imaging method of this preferred embodiment, as shown in Figure 3 shown, the magnetic resonance imaging method includes the following steps:

[0060] Step S302, collect spin echo images with different echo times for the quantitative object.

[0061] Specifically, perform nuclear magnetic resonance scanning on the target object according to the set pulse sequence and collect spin echo images with different echo times. In some embodiments, the set pulse sequence can be a spin echo sequence.

[0062] Step S304, calculate the diffusion sensitivity coefficients corresponding to different echo times in the spin echo sequence.

[0063] Specifically, the corresponding b value can be determined according to different echo times TE. Among them, b is the diffusion sensitivity coefficient, which represents the time, amplitude, and shape of the applied diffusion gradient magnetic field. The higher the b value, the greater the diffusion weight, the more sensitive to the diffusion movement of water molecules, and the more obvious the signal drop. The unit of the b value is s / mm 2 .

[0064] Step S306, use a sequence with a diffusion encoding gradient to scan the target area and generate an ADC map to obtain the spatially corresponding apparent diffusion coefficient. Among them, the unit of the apparent diffusion coefficient is mm 2 / s.

[0065] Specifically, the sequence with a diffusion-encoding gradient includes an echo-planar diffusion-weighted imaging sequence. The sequence with a diffusion-encoding gradient maintains the same geometric position, image size, and voxel size as the first magnetic resonance sequence. When acquiring DWI images with different b values by applying the sequence with a diffusion-encoding gradient, the signals of the multiple acquired DWI images show an exponential decay with ADC as the attenuation coefficient as the b value changes. By performing an exponential function fitting on the DWI images with multiple diffusion-sensitizing coefficient b values, an ADC map can be calculated. According to the formula apparent diffusion coefficient D = Ln(S2 / S1) / (b1 - b2), the value of the apparent diffusion coefficient D can be calculated.

[0066] Step S308: According to the obtained echo time, diffusion-sensitizing coefficient, and apparent diffusion coefficient, fit the T2 value voxel by voxel.

[0067] Specifically, substitute the obtained echo time TE value, diffusion-sensitizing coefficient b value, and apparent diffusion coefficient D value into the transverse relaxation time quantification formula (2) considering the influence of diffusion, and fit the T2 value voxel by voxel.

[0068] Among them, S(TE) represents the signal intensity at TE, that is, the spin echo image data, M xy represents the transverse magnetization vector, TE represents the echo time, T2 represents the transverse relaxation time constant, b represents the diffusion-sensitizing coefficient, and D represents the apparent diffusion coefficient. In formula (2), only M xy and T2 are unknown, and through maximum-minimum calculation processing, the T2 value corresponding to each voxel can be obtained.

[0069] Step S310: Combine the T2 values of the voxels to obtain a T2 quantification image that effectively corrects the influence of diffusion.

[0070] Specifically, according to the T2 value corresponding to each voxel obtained in step S308, combining the T2 values corresponding to these voxels can generate a two-dimensional image, that is, a T2 quantification image. The influence of diffusion is eliminated during the fitting process of this T2 quantification image, and the quantification accuracy is improved.

[0071] Through the above steps S302 to S310, by executing the above magnetic resonance data processing flow, it is possible to effectively correct the influence of diffusion in the spin-echo method with variable echo time under any gradient timing that conforms to the sequence design.

[0072] It should be noted that the steps shown in the above process or the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0073] In this embodiment, a magnetic resonance imaging device is further provided. This device is used to implement the above-mentioned embodiments and preferred implementation manners, and those that have been described will not be repeated here. The following terms such as "module", "unit", "sub-unit", etc. can be a combination of software and / or hardware that can achieve a predetermined function. Although the device described in the following embodiments is preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0074] Figure 4 is a structural block diagram of a magnetic resonance imaging device according to this embodiment. As Figure 4 shown, the device includes:

[0075] A first scanning module 10, configured to scan a target area using a first magnetic resonance sequence, set multiple echo times, and acquire multiple spin echo images;

[0076] A recording module 20, configured to record multiple echo times and corresponding diffusion sensitivity coefficients according to the first magnetic resonance sequence;

[0077] A second scanning module 30, configured to scan the target area using a second magnetic resonance sequence to obtain an apparent diffusion coefficient;

[0078] A fitting module 40, configured to fit a transverse relaxation time constant quantitative image for correcting the diffusion effect according to multiple spin echo images, multiple echo times, diffusion sensitivity coefficients, and apparent diffusion coefficients.

[0079] It should be noted that the above-mentioned each module can be a functional module or a program module, and can be implemented either by software or by hardware. For the modules implemented by hardware, the above-mentioned each module can be located in the same processor; or the above-mentioned each module can also be located in different processors in any combined form.

[0080] In this embodiment, an electronic device is further provided, including a memory and a processor. A computer program is stored in the memory, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0081] Optionally, the above-mentioned electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the above-mentioned processor, and the input / output device is connected to the above-mentioned processor.

[0082] Optionally, in this embodiment, the above-mentioned processor may be configured to execute the following steps through a computer program:

[0083] S1, scan a target area using a first magnetic resonance sequence, set multiple echo times, and acquire multiple spin echo images.

[0084] S2. Record a plurality of echo times and corresponding diffusion sensitivity coefficients according to the first magnetic resonance sequence.

[0085] S3. Scan the target region using the second magnetic resonance sequence to obtain the apparent diffusion coefficient.

[0086] S4. Fit a transverse relaxation time constant quantitative image that corrects for the diffusion effect based on the plurality of spin echo images, the plurality of echo times, the diffusion sensitivity coefficients, and the apparent diffusion coefficient.

[0087] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementation manners, and will not be elaborated in this embodiment.

[0088] In addition, in combination with the method for magnetic resonance imaging provided in the above embodiments, a storage medium can also be provided in this embodiment to implement it. A computer program is stored on the storage medium; when the computer program is executed by a processor, any one of the methods for magnetic resonance imaging in the above embodiments is implemented.

[0089] It should be understood that the specific embodiments described here are only used to explain this application, rather than to limit it. According to the embodiments provided in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0090] Obviously, the drawings are only some examples or embodiments of the present application. For those of ordinary skill in the art, the present application can also be applied to other similar situations based on these drawings without creative work. Additionally, it can be understood that although the work done during this development process may be complex and time-consuming, for those of ordinary skill in the art, certain design, manufacturing, or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be regarded as insufficient disclosure of the present application.

[0091] The term "embodiment" in the present application means that the specific features, structures, or characteristics described in combination with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily mean the same embodiment, nor does it mean being independent or alternative to other embodiments and mutually exclusive. Those of ordinary skill in the art can clearly or implicitly understand that the embodiments described in the present application can be combined with other embodiments without conflict.

[0092] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of patent protection. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for magnetic resonance imaging, characterized in that, The method for magnetic resonance imaging includes: Scanning a target region using a first magnetic resonance sequence, setting multiple echo times, and acquiring multiple spin echo images; Recording the multiple echo times and corresponding diffusion sensitivity coefficients according to the first magnetic resonance sequence; Scanning the target region using a second magnetic resonance sequence to obtain an apparent diffusion coefficient; Fitting a transverse relaxation time constant quantitative image corrected for diffusion effects based on the multiple spin echo images, the multiple echo times, the diffusion sensitivity coefficients, and the apparent diffusion coefficient.

2. The method for magnetic resonance imaging according to claim 1, wherein, The first magnetic resonance sequence is a spin echo sequence for scanning to obtain the spin echo images; The second magnetic resonance sequence is a magnetic resonance sequence with diffusion encoding gradients for obtaining the apparent diffusion coefficient of the target tissue.

3. The method for magnetic resonance imaging according to claim 2, wherein The spin echo sequence is a single echo spin echo pulse sequence.

4. The method for magnetic resonance imaging according to claim 2, wherein The magnetic resonance sequence with diffusion encoding gradients includes an echo planar diffusion weighted imaging sequence.

5. The method for magnetic resonance imaging according to claim 2, characterized in that, The step of scanning the target region using the second magnetic resonance sequence to obtain an apparent diffusion coefficient includes: The second magnetic resonance sequence is set with the same position, image size, and voxel size as the first magnetic resonance sequence; The second magnetic resonance sequence scans the target region by setting multiple magnetic resonance sequences with the diffusion encoding gradients, fits and generates a two-dimensional map including the apparent diffusion coefficient, and obtains the apparent diffusion coefficient according to the two-dimensional map.

6. The method for magnetic resonance imaging according to claim 1, wherein The step of fitting a transverse relaxation time constant quantitative image corrected for diffusion effects based on the multiple spin echo images, the multiple echo times, the diffusion sensitivity coefficients, and the apparent diffusion coefficient includes: Obtaining the correspondence between the signal intensity and the transverse magnetization vector, the echo time, the transverse relaxation time constant, the diffusion sensitivity coefficient, and the apparent diffusion coefficient; Fitting the transverse relaxation time constant quantitative image corrected for diffusion effects voxel by voxel based on the correspondence, the signal intensity, the multiple echo times, the diffusion sensitivity coefficients corresponding to the multiple echo times, and the apparent diffusion coefficient.

7. The method for magnetic resonance imaging according to claim 6, characterized in that, The step of obtaining the correspondence between the signal intensity and the transverse magnetization vector, the echo time, the transverse relaxation time constant, the diffusion sensitivity coefficient, and the apparent diffusion coefficient includes: Generating a first coefficient according to the exponential function of the ratio of the echo time to the transverse relaxation time constant; Generating a second coefficient according to the exponential function of the product of the diffusion sensitivity coefficient and the apparent diffusion coefficient; Generating a third coefficient according to the product of the transverse magnetization vector, the first coefficient, and the second coefficient; Generating the correspondence according to the signal intensity and the third coefficient.

8. An apparatus for magnetic resonance imaging, characterized in that, The apparatus for magnetic resonance imaging includes: A first scanning module for scanning a target region using a first magnetic resonance sequence, setting multiple echo times, and acquiring multiple spin echo images; A recording module for recording the multiple echo times and corresponding diffusion sensitivity coefficients according to the first magnetic resonance sequence; A second scanning module for scanning the target region using a second magnetic resonance sequence to obtain an apparent diffusion coefficient; A fitting module, configured to obtain a quantitative image of the transverse relaxation time constant for correcting diffusion effects by fitting based on the multiple spin echo images, the multiple echo times, the diffusion sensitivity coefficient, and the apparent diffusion coefficient.

9. An electronic device, comprising a memory and a processor, characterized in that, A computer program is stored in the memory, and the processor is configured to run the computer program to execute the magnetic resonance imaging method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the magnetic resonance imaging method according to any one of claims 1 to 7 are implemented.

Images