Dispersion sensitive factor calculation method, magnetic resonance imaging method and system

Abstract

The invention relates to a dispersion sensitive factor calculation method and a magnetic resonance imaging method and system.The dispersion sensitive factor calculation method comprises the steps that the distribution condition of stimulation echoes in each target component in echo signals is obtained; the distribution condition indicates the forming times and positions of the stimulation echoes; determining a weight coefficient of each target component relative to an echo signal based on the distribution condition of stimulation echoes; and determining a target dispersion sensitive factor according to the weight coefficient, the target component and the distribution condition of the stimulation echoes. According to the method and the device, the influence of the stimulation echo generated in the sequence on the dispersion sensitive factor can be considered, the calculation precision of the dispersion sensitive factor is improved, and the problem that the dispersion sensitive factor cannot be accurately calculated is solved.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic resonance imaging, and particularly to a method for calculating a diffusion sensitivity factor, a magnetic resonance imaging method, and a system. Background Art

[0002] The basic principle of magnetic resonance imaging is to generate a macroscopic magnetization vector of protons in the object to be measured through an externally applied magnetic field, and to excite the macroscopic magnetization vector to precess around the magnetic field direction by applying a radio frequency pulse sequence, thereby generating a magnetic resonance signal and forming a magnetic resonance image. By applying different radio frequency pulse sequences, the differences in certain characteristics between tissues of the object to be measured can be emphasized to meet different imaging requirements.

[0003] Diffusion-Weighted Imaging (DWI) can reflect the contrast of water molecule diffusion between tissues and is a commonly used brain imaging method at present. In addition, diffusion phenomena also exist in some non-diffusion imaging. Among them, the diffusion sensitivity factor can reflect the diffusion ability of the magnetic resonance sequence to the signal and is of great significance for imaging. At present, the calculation of the diffusion sensitivity factor only considers the influence of the spin echoes (SE) generated by the radio frequency pulse sequence. However, under the combined action of multiple radio frequency pulses in the sequence, stimulated echoes will also be generated, which affects the calculation of the diffusion sensitivity factor and an accurate diffusion sensitivity factor cannot be obtained.

[0004] In view of the problem in the related art that the diffusion sensitivity factor cannot be accurately calculated, no effective solution has been proposed yet. Summary of the Invention

[0005] Based on this, in view of the above technical problems, it is necessary to provide a method for calculating a diffusion sensitivity factor, a magnetic resonance imaging method, and a system that can accurately calculate the diffusion sensitivity factor.

[0006] In a first aspect, a method for calculating a diffusion sensitivity factor is provided in this embodiment, including:

[0007] Obtaining the distribution of stimulated echoes in each target component in the echo signal; the distribution indicates the number of times and positions where the stimulated echoes are formed;

[0008] Determining the weight coefficient of each target component relative to the echo signal based on the distribution of the stimulated echoes;

[0009] Determining a target diffusion sensitivity factor according to the weight coefficient, the target component, and the distribution of the stimulated echoes.

[0010] In some of these embodiments, the above method further includes: acquiring the echo signal by applying an echo sequence; the echo signal includes a spin echo and the stimulated echo.

[0011] In some of these embodiments, obtaining the distribution of the stimulated echo in each target component in the acquired echo signal includes:

[0012] Determining the component located at the center of the K-space in the echo signal as the target component;

[0013] Based on the radio frequency pulses in the echo sequence, determining the number and position of the stimulated echo in the target component.

[0014] In some of these embodiments, based on the distribution of the stimulated echo, determining the weight coefficient of each target component relative to the echo signal includes:

[0015] Based on the distribution of the stimulated echo, obtaining the target component;

[0016] Based on the target component and the echo spacing in the echo sequence, obtaining the weight coefficient of each target component.

[0017] In some of these embodiments, the above method further includes: representing the target component in the form of a spin echo and a stimulated echo;

[0018] wherein, the spin echo and the stimulated echo are represented by the flip angle of the corresponding radio frequency pulse in the echo sequence.

[0019] In some of these embodiments, determining the target diffusion sensitivity factor according to the weight coefficient, the target component, and the distribution of the stimulated echo includes:

[0020] Calculating the diffusion sensitivity factor of each target component according to the position of the stimulated echo in the echo sequence and the distribution of the stimulated echo;

[0021] Based on the weight coefficient, performing a weighting process on the diffusion sensitivity factor of each target component to obtain the target diffusion factor.

[0022] In some of these embodiments, the above method further includes: determining a diffusion coefficient based on the target diffusion factor; the diffusion coefficient is used for diffusion weighted imaging.

[0023] Second aspect, in this embodiment, a magnetic resonance imaging method is provided, including:

[0024] Determining a diffusion coefficient based on the target diffusion sensitivity factor obtained by the diffusion sensitivity factor calculation method described in the above first aspect;

[0025] Diffusion-weighted imaging is performed based on the diffusion coefficient to obtain a magnetic resonance image.

[0026] In a third aspect, a magnetic resonance imaging system is provided in this embodiment, including:

[0027] A magnetic resonance scanning device for applying an echo sequence to form a radio frequency field and receiving an echo signal through a radio frequency coil;

[0028] A controller for executing the diffusion sensitivity factor calculation method described in the first aspect or the magnetic resonance imaging method described in the second aspect.

[0029] In a fourth aspect, a computer 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, it implements the diffusion sensitivity factor calculation method described in the first aspect or the magnetic resonance imaging method described in the second aspect.

[0030] In a fifth aspect, a storage medium is provided in this embodiment, on which a computer program is stored. When the program is executed by a processor, it implements the diffusion sensitivity factor calculation method described in the first aspect or the magnetic resonance imaging method described in the second aspect.

[0031] Compared with the related art, a diffusion sensitivity factor calculation method, a magnetic resonance imaging method, and a system provided in this embodiment can consider the influence of the stimulated echo generated in the sequence on the diffusion sensitivity factor by obtaining the distribution of the stimulated echo in each target component in the echo signal; the distribution indicates the number and position of the formation of the stimulated echo; based on the distribution of the stimulated echo, determining the weight coefficient of each target component relative to the echo signal; and determining the target diffusion sensitivity factor according to the weight coefficient, the target component, and the distribution of the stimulated echo, improving the calculation accuracy of the diffusion sensitivity factor and solving the problem of being unable to accurately calculate the diffusion sensitivity factor.

[0032] 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

[0033] 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:

[0034] Figure 1 It is a hardware structure block diagram of a terminal of the diffusion sensitivity factor calculation method in an embodiment;

[0035] Figure 2 is a flowchart of a method for calculating a diffusion sensitivity factor in an embodiment;

[0036] Figure 3 is a schematic diagram of a stimulated echo in an embodiment;

[0037] Figure 4 is a schematic diagram of a target component in an embodiment;

[0038] Figure 5 is a flowchart of a method for calculating a diffusion sensitivity factor in another embodiment;

[0039] Figure 6 is a structural block diagram of a diffusion sensitivity factor calculation device in an embodiment.

[0040] In the figure: 102, a processor; 104, a memory; 106, a transmission device; 108, an input / output device; 10, an acquisition module; 20, a weight coefficient determination module; 30, a diffusion sensitivity factor calculation module. Detailed implementation manners

[0041] For a clearer understanding of the purpose, technical solution, and advantages of the present application, the present application will be described and explained below with reference to the accompanying drawings and embodiments.

[0042] 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 can be singular or plural. The terms "include", "comprise", "have" and any variants thereof used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes 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", "coupled" and the like used in this application do not limit to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The term "plurality" used in this application means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, "A and / or B" may 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. used in this application only distinguish similar objects and do not represent a specific order for the objects.

[0043] The method embodiment provided in this embodiment can be executed on a terminal, a computer or a similar computing device. For example, it runs on a terminal. Figure 1 It is a hardware structure block diagram of the terminal of the diffusion sensitivity factor calculation method in this embodiment. As Figure 1 shown, the terminal may include one or more ( Figure 1 only one is shown in Figure 1 ) 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 also 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 also include more or fewer components than Figure 1 shown, or have a different configuration from

[0044] 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 the diffusion sensitivity factor calculation method in this embodiment. The processor 102 executes various functional applications and data processing by running the computer programs stored in the memory 104, that is, implements the above-mentioned method. The memory 104 may include a high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memories, 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 their combinations.

[0045] 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 (Radio Frequency, abbreviated as RF) module, which is used to communicate with the Internet wirelessly.

[0046] The basic principle of magnetic resonance imaging is to apply an external magnetic field to make the protons in the object to be measured generate a macroscopic magnetization vector in the body, and by applying a radio frequency pulse sequence, the macroscopic magnetization vector is excited to precess around the magnetic field direction, thereby generating a magnetic resonance signal. After collecting the magnetic resonance signal, the magnetic resonance signal is reconstructed through spatial phase encoding technology to obtain the tissue image of the object to be measured, forming a magnetic resonance image. By applying different radio frequency pulse sequences, it is possible to focus on reflecting the differences in certain characteristics between tissues of the object to be measured to meet different imaging requirements.

[0047] Diffusion-Weighted Imaging (DWI) can reflect the contrast of the diffusion of water molecules between tissues, and it is a currently commonly used cranial imaging method. In addition, there is also a diffusion phenomenon in some non-diffusion imaging. Among them, the diffusion sensitivity factor can reflect the strength of the diffusion signal, which is of great significance for imaging. Currently, the calculation of the diffusion sensitivity factor only considers the influence of the spin echoes (SE) generated by the radio frequency pulse sequence, but under the combined action of multiple radio frequency pulses in the sequence, a stimulated echo will also be generated, thereby affecting the calculation of the diffusion sensitivity factor and making it impossible to obtain an accurate diffusion sensitivity factor.

[0048] In this embodiment, a method for calculating the diffusion sensitivity factor is provided.Figure 2 is the flowchart of the diffusion sensitivity factor calculation method in this embodiment. As Figure 2 shown, this method includes the following steps:

[0049] Step S210, obtaining the distribution of the stimulated echo in each target component in the echo signal; the distribution indicates the number and position of the formed stimulated echoes.

[0050] Specifically, by applying an echo sequence such as a diffusion-weighted sequence or a non-diffusion-weighted sequence, the echo signal is obtained, and the target component in the echo signal is determined by a pre-specified K-space region.

[0051] In some cases, when the second radio frequency pulse in the echo sequence is excited, the FID (free induction decay) signal generated by the previous radio frequency pulse has not completely decayed. Then, the second radio frequency pulse will have a focusing effect on the FID signal of the previous radio frequency pulse, thereby generating a spin echo. By applying three or more radio frequency pulses, a focusing effect is generated on some of the self-selected echoes again, thereby generating a stimulated echo. Figure 3 is the schematic diagram of the stimulated echo in this embodiment. As Figure 3 shown, three radio frequency pulses are applied respectively, and their angles are α 1 、α 2 、α 3 . After a spin echo is generated by two consecutive radio frequency pulses, a stimulated echo is generated by three radio frequency pulses.

[0052] According to the applied echo sequence, the distribution of the stimulated echo in the target component is obtained. The distribution includes, but is not limited to, the number and position of the formed stimulated echoes in the target component.

[0053] Step S220, determining the weight coefficient of each target component relative to the echo signal based on the distribution of the stimulated echo.

[0054] Specifically, by applying an echo sequence, the echo signal is obtained, where the echo signal includes a spin echo and a stimulated echo. Correspondingly, the target component also includes a spin echo and a stimulated echo.

[0055] Based on the number and position of the formed stimulated echoes in the target component in the distribution of the stimulated echo, the target component represented by the spin echo and the stimulated echo is obtained. Among them, the spin echo and the stimulated echo are respectively represented by the radio frequency pulses corresponding to each spin echo and stimulated echo generated in the echo sequence.

[0056] According to the target component and the echo interval in the echo sequence, the proportion of each target component in the echo signal is calculated, that is, the weight coefficient relative to the echo signal.

[0057] Further, according to the distribution of stimulated echoes, the target components can be grouped and classified, and the weight coefficients can be calculated for each group of target components. For example, the target components can be grouped according to the number of times the target components experience stimulated echoes, and then each target component in each group can be further divided according to the position where the stimulated echoes are formed.

[0058] Step S230: Determine the target diffusion sensitivity factor according to the weight coefficients, the target components, and the distribution of the stimulated echoes.

[0059] Specifically, the diffusion sensitivity factor can reflect the diffusion ability of the magnetic resonance sequence to the signal, and is an important inherent attribute parameter of the echo sequence (such as the diffusion-weighted sequence), which is only related to the sequence gradient and the RF arrangement.

[0060] According to the position of the stimulated echoes in the distribution, combined with the gradient of the echo sequence, the diffusion sensitivity factor of each target component is calculated respectively. Based on the weight coefficients, the diffusion sensitivity factors of each target component are weighted to obtain the target diffusion sensitivity factor.

[0061] The above steps include obtaining the distribution of the stimulated echoes in each target component in the echo signal; the distribution indicates the number of times and the position where the stimulated echoes are formed; based on the distribution of the stimulated echoes, determining the weight coefficients of each target component relative to the echo signal; and determining the target diffusion sensitivity factor according to the weight coefficients, the target components, and the distribution of the stimulated echoes. Compared with the prior art that only considers the influence of the spin echoes generated by the RF pulse sequence on the calculation of the diffusion factor, the present application obtains the distribution of the stimulated echoes in each target component in the echo signal and determines the weight coefficients of each target component relative to the echo signal, which can consider the influence of the stimulated echoes generated in the sequence on the diffusion sensitivity factor, improve the calculation accuracy of the diffusion sensitivity factor, and solve the problem of inaccurate calculation of the diffusion sensitivity factor.

[0062] In some of the embodiments, the above method further includes: collecting an echo signal by applying an echo sequence; the echo signal includes spin echoes and stimulated echoes.

[0063] Specifically, an echo signal is obtained by applying an echo sequence such as a diffusion-weighted sequence or a non-diffusion-weighted sequence. In diffusion imaging, the diffusion-weighted sequence refers to various sequences designed specifically to increase diffusion sensitivity, which add motion-sensitive gradient fields on the basis of traditional sequences (such as spin echo sequences, fast spin echo sequences, or gradient echo sequences, etc.), and can show signal differences caused by different diffusion speeds of water molecules in different tissues. For non-diffusion imaging, an echo signal is collected by applying a non-diffusion-weighted sequence.

[0064] In this embodiment, echo sequences such as diffusion-weighted sequences or non-diffusion-weighted sequences are applied to obtain echo signals, thereby providing echo signals for subsequent determination of the distribution of stimulated echoes in the target components.

[0065] In some of these embodiments, obtaining the distribution of stimulated echoes in each target component in step S210 can be achieved through the following steps:

[0066] Step S211, determining the components located at the center of the K-space in the echo signal as the target components.

[0067] Step S212, determining the number and positions of the stimulated echoes in the target components based on the radiofrequency pulses in the echo sequence.

[0068] Specifically, in magnetic resonance imaging, the calculation of the diffusion sensitivity factor is mainly affected by the echo signals at the center of the K-space. In this embodiment, the components located at the center of the K-space in the echo signal are determined as the target components.

[0069] Based on the radiofrequency pulses in the echo sequence, after applying the first radiofrequency pulse (as the excitation pulse) for excitation, several radiofrequency pulses (as refocusing pulses) are continuously applied to form spin echoes and stimulated echoes. For example, the spin echo is formed after the target component experiences the i-th refocusing pulse, and the stimulated echo is formed after the target component experiences the i-th and (i + 1)-th refocusing pulses, thereby determining the number and positions of the stimulated echoes in the target components.

[0070] In this embodiment, the number and positions of the stimulated echoes in the target components are determined according to the radiofrequency pulses in the echo sequence, thereby obtaining the distribution of the target components in the stimulated echoes, and further determining the weight coefficients of each target component according to the distribution in the subsequent process, which can consider the influence of the stimulated echoes generated in the sequence on the diffusion sensitivity factor and reflect it with the weight coefficients.

[0071] In some of these embodiments, the above step S220 of determining the weight coefficient of each target component relative to the echo signal based on the distribution of the stimulated echoes can be achieved through the following steps:

[0072] Step S221, obtaining the target components based on the distribution of the stimulated echoes.

[0073] Specifically, by applying an echo sequence, echo signals are obtained, where the echo signals include spin echoes and stimulated echoes. Correspondingly, the target components also include spin echoes and stimulated echoes.

[0074] Based on the number of times and positions where the stimulated echoes are formed in the target component in the distribution of the stimulated echoes, the target component represented by the spin echo and the stimulated echo is obtained. Among them, the spin echo and the stimulated echo are respectively represented by the radio frequency pulses corresponding to generating each spin echo and stimulated echo in the echo sequence.

[0075] Further, the target component is represented in the form of a spin echo and a stimulated echo; among them, the spin echo and the stimulated echo are represented by the flip angles of the corresponding radio frequency pulses in the echo sequence.

[0076] Figure 4 It is a schematic diagram of the target component in this embodiment. Before obtaining the target component, the number of refocusing pulses in the echo sequence is N. For example, when N is 6, there are a total of 13 target components in the echo signal.

[0077] Such as Figure 4 shown, A i represents the spin echo, which is formed after the target component experiences the i-th refocusing pulse. (B i B i+1 ) represents the stimulated echo, which is formed after the target component experiences the i-th and (i + 1)-th refocusing pulses. For 1 target component that experiences 0 stimulated echoes, it only contains spin echoes; for 5 target components that experience 1 stimulated echo and 6 target components that experience 2 stimulated echoes, they are divided according to the positions where the stimulated echoes are formed; for 1 target component that experiences 3 stimulated echoes, it only contains stimulated echoes.

[0078] Among them, the spin echo A i and the stimulated echo (B i B i+1 ) are expressed as follows:

[0079]

[0080]

[0081] Among them, θ i is the flip angle of the i-th refocusing pulse.

[0082] Step S222, based on the target component and the echo interval in the echo sequence, obtain the weight coefficient of each target component.

[0083] Specifically, according to the target component and the echo interval in the echo sequence, calculate the proportion of each target component in the echo signal, that is, the weight coefficient of each target component relative to the echo signal. Among them, according to the echo interval in the echo sequence and T 2The relaxation time determines the signal attenuation degree of each target component within an echo interval, and then, based on the target component and the signal attenuation degree of the target component within an echo interval, the weight coefficient of each target component is calculated.

[0084] The following is a calculation expression for the weight coefficient w of each target component k,q :

[0085] W k,q = A 1 A 2 …(B i B i+1 )…A N T N-k ;

[0086] Wherein,

[0087]

[0088] k represents the number of times each target component experiences a stimulated echo; after grouping by the number of times of stimulated echo, q represents the position order of each target component in each group of target components; i represents a refocusing pulse; N represents the number of refocusing pulses in the echo sequence; A 1 A 2 …(B i B i+1 )…A N represents the target component, and the target component is represented by the product of a spin echo and a stimulated echo; A 1 、A 2 、A N represent spin echoes; (B i B i+1 ) represents the stimulated echo formed after the target component experiences the i-th and (i + 1)-th refocusing pulses; T represents the signal attenuation degree of the target component within an echo interval; T 2 represents T 2 relaxation time, and T echo represents the echo interval of the echo sequence.

[0089] In this embodiment, by according to the distribution of the stimulated echoes in the target component, the influence of the stimulated echoes generated in the sequence on the diffusion sensitivity factor can be considered and reflected by the weight coefficient of each target component relative to the echo signal, so that the target diffusion sensitivity factor of the echo sequence can be calculated according to the weight coefficient of each target component.

[0090] In some of these embodiments, the above step S230 of determining the target diffusion sensitivity factor according to the weight coefficient, the target component, and the distribution of the stimulated echoes can be implemented by the following steps:

[0091] Step S231: Calculate the diffusion sensitivity factor of each target component according to the position of the stimulated echo in the echo sequence and the distribution of the stimulated echoes.

[0092] Specifically, according to the position in the distribution of the stimulated echoes and in combination with the gradient of the echo sequence, calculate the diffusion sensitivity factor of each target component respectively. Among them, for the two refocusing pulses before the position where the stimulated echo is formed, the gradient amplitude between them is regarded as 0.

[0093] The following is a calculation expression for the diffusion sensitivity factor b of each target component: k,q One kind of calculation expression:

[0094] b k,q = G 2 γ 2 δ 2 (Δ - δ / 3);

[0095] Among them, G represents the diffusion gradient amplitude; γ represents the gyromagnetic ratio; Δ represents the interval between two diffusion gradients; δ represents the duration of one diffusion gradient.

[0096] Step S232: Based on the weight coefficient, perform weighted processing on the diffusion sensitivity factor of each target component to obtain the target diffusion factor.

[0097] Specifically, based on the weight coefficient, perform weighted processing on the diffusion sensitivity factor of each target component, and obtain the target diffusion factor according to the ratio between the weighted sum of the diffusion sensitivity factors and the weighted sum of the weight coefficients.

[0098] The following is a calculation expression for the target diffusion sensitivity factor b:

[0099]

[0100] Among them, b k,q represents the diffusion sensitivity factor of each target component; W k,q represents the weight coefficient of each target component; k represents the number of times the target component experiences the stimulated echo; N represents the number of refocusing pulses in the echo sequence; after grouping by the number of times of experiencing the stimulated echo, P represents the number of target components in each group; q represents the position order of each target component in each group of target components.

[0101] In this embodiment, by obtaining the weight coefficient and the diffusion sensitivity factor of each target component, an accurately calculated target diffusion sensitivity factor is comprehensively obtained. On the one hand, it is beneficial to improve the imaging quality of diffusion imaging. On the other hand, for non-diffusion imaging, it can improve the evaluation accuracy of the diffusion sensitivity factor therein.

[0102] This application also provides a magnetic resonance imaging method, including:

[0103] Determine the diffusion coefficient based on the target diffusion sensitivity factor obtained by the diffusion sensitivity factor calculation method in any of the above embodiments; perform diffusion-weighted imaging based on the diffusion coefficient to obtain a magnetic resonance image.

[0104] Specifically, the diffusion coefficient is a parameter that describes the diffusion characteristics of a substance. The diffusion coefficient in magnetic resonance imaging is a physical quantity that measures the degree of water molecule diffusion in a living organism in diffusion-weighted imaging (DWI). In diffusion-weighted imaging, the diffusion factor (b value) is changed by changing the diffusion gradient, thereby affecting the image signal of the diffusion-weighted imaging. The image signal of the diffusion-weighted imaging decays in an exponential form with different diffusion factors, and the diffusion coefficient is the decay coefficient, which can indirectly reflect the tissue structure of the living organism. Therefore, diffusion-weighted imaging is performed based on the diffusion coefficient.

[0105] In this embodiment, by calculating an accurate target diffusion sensitivity factor, the imaging quality of diffusion imaging is improved.

[0106] The following describes and illustrates this embodiment through preferred embodiments.

[0107] Figure 5 is a flowchart of the diffusion sensitivity factor calculation method in this embodiment, as Figure 5 shown, the method includes the following steps:

[0108] Step S510, collect echo signals by applying an echo sequence, and extract the echo signal at the center of the k-space as the target component.

[0109] Step S520, determine the number and position of the stimulated echoes in the target component based on the radiofrequency pulses in the echo sequence.

[0110] Step S530, obtain the target component represented in the form of spin echoes and stimulated echoes based on the number and position of the stimulated echoes in the target component.

[0111] Step S540, obtain the weight coefficient of each target component based on the target component and the echo spacing in the echo sequence.

[0112] Step S550, calculate the diffusion sensitivity factor of each target component according to the position of the stimulated echo in the echo sequence and the distribution of the stimulated echoes; based on the weight coefficient, perform weighted processing on the diffusion sensitivity factor of each target component to obtain the target diffusion factor.

[0113] Step S560, determine the diffusion coefficient based on the target diffusion factor; the diffusion coefficient is used for diffusion-weighted imaging.

[0114] 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.

[0115] By obtaining the distribution of the stimulated echo in each target component in the echo signal in this embodiment and determining the weight coefficient of each target component relative to the echo signal, the influence of the stimulated echo generated in the sequence on the diffusion sensitivity factor can be considered, the calculation accuracy of the diffusion sensitivity factor is improved, and the imaging quality of diffusion-weighted imaging is further improved.

[0116] In this embodiment, a diffusion sensitivity factor calculation device is also provided. This device is used to implement the above embodiments and preferred implementation manners, and those that have been described will not be repeated here. The terms "module", "unit", "sub-unit", etc. used below can be a combination of software and / or hardware that can achieve a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0117] Figure 6 is the structural block diagram of the diffusion sensitivity factor calculation device of this embodiment, as Figure 6 shown, the device includes: an acquisition module 10, a weight coefficient determination module 20, and a diffusion sensitivity factor calculation module 30.

[0118] The acquisition module 10 is used to obtain the distribution of the stimulated echo in each target component in the echo signal; the distribution indicates the number of times and positions where the stimulated echo is formed.

[0119] The weight coefficient determination module 20 is used to determine the weight coefficient of each target component relative to the echo signal based on the distribution of the stimulated echo.

[0120] The diffusion sensitivity factor calculation module 30 is used to determine the target diffusion sensitivity factor according to the weight coefficient, the target component, and the distribution of the stimulated echo.

[0121] By using the device provided in this embodiment to obtain the distribution of the stimulated echo in each target component in the echo signal and determine the weight coefficient of each target component relative to the echo signal, the influence of the stimulated echo generated in the sequence on the diffusion sensitivity factor can be considered, the calculation accuracy of the diffusion sensitivity factor is improved, and the problem of being unable to accurately calculate the diffusion sensitivity factor is solved.

[0122] It should be noted that the above-mentioned modules can be functional modules or program modules, and can be implemented either by software or by hardware. For the modules implemented by hardware, the above-mentioned modules can be located in the same processor; or the above-mentioned modules can also be located in different processors in any combined form.

[0123] This application also provides a magnetic resonance imaging system, including: a magnetic resonance scanning device for applying an echo sequence to form a radio frequency field and receiving an echo signal through a radio frequency coil;

[0124] A controller for executing the diffusion sensitivity factor calculation method or the magnetic resonance imaging method in the above embodiments.

[0125] Among them, after the magnetic resonance imaging system receives a scan instruction, it obtains the pulse sequence corresponding to this scan instruction (i.e., the echo sequence in the above embodiments), and performs magnetic resonance scanning based on the pulse waveform corresponding to the echo sequence emitted by the magnetic resonance scanning device to execute this pulse sequence. The magnetic resonance scanning device includes various coils, such as an RF transmitting coil, an RF receiving coil, etc., and gradient coils, etc. The magnetic resonance signal (i.e., the echo signal in the above embodiments) can be received or the corresponding pulse can be emitted through the coils of the magnetic resonance scanning device, and the controller obtains the received echo signal and calculates the target diffusion sensitivity factor or performs magnetic resonance imaging accordingly.

[0126] This application also provides a computer device. The magnetic resonance imaging system includes a processor, a memory, and a magnetic resonance scanning device. A computer program is stored in the memory, and the processor is configured to run this computer program to execute the diffusion sensitivity factor calculation method or the magnetic resonance imaging method in the embodiments of this application. The processor controls the magnetic resonance scanning device to emit a target pulse waveform for magnetic resonance scanning.

[0127] Optionally, the above computer device may further include a transmission device and an input / output device. Among them, the transmission device is connected to the above processor, and the input / output device is connected to the above processor.

[0128] 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 repeated in this embodiment.

[0129] In addition, in combination with the diffusion sensitivity factor calculation method provided in the above embodiments, a storage medium can also be provided to implement it in this embodiment. A computer program is stored on this storage medium; when this computer program is executed by a processor, it implements any one of the diffusion sensitivity factor calculation methods or magnetic resonance imaging methods in the above embodiments.

[0130] It should be understood that the specific embodiments described herein are for explaining this application rather than limiting it. All other embodiments obtained by those of ordinary skill in the art without creative efforts according to the embodiments provided in this application fall within the protection scope of this application.

[0131] Obviously, the accompanying drawings are only some examples or embodiments of this application. For those of ordinary skill in the art, this application can also be applied to other similar situations based on these drawings without creative efforts. 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 this application are only routine technical means and should not be regarded as insufficient disclosure of this application.

[0132] The term "embodiment" in this application means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of this application. The phrase appears in various positions in the specification and 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 this application can be combined with other embodiments without conflict.

[0133] The above-described embodiments only represent several implementation manners of this application. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of patent protection. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be subject to the appended claims.

Claims

1. A method for calculating a diffusion sensitivity factor, characterized in that: include: Acquiring the distribution of the stimulus echo in each target component in the echo signal; the distribution indicates the number and position of the stimulus echo; Determining a weight coefficient of each target component relative to the echo signal based on the distribution of the stimulus echo; A target diffusion sensitivity factor is determined according to the weight coefficient, the target component and the distribution of the stimulation echo.

2. The method for calculating the diffusion sensitivity factor according to claim 1, characterized in that: Also includes: The echo signal is collected by applying an echo sequence; the echo signal includes a spin echo and the stimulation echo.

3. The method for calculating the diffusion sensitivity factor according to claim 1, characterized in that: The obtaining of the distribution of the stimulus echo in each target component in the echo signal includes: Determine the component of the echo signal located at the center of the K space as the target component; The number and position of the stimulation echo in the target component are determined based on the radio frequency pulses in the echo sequence.

4. The method for calculating the diffusion sensitivity factor according to claim 2, characterized in that: The step of determining a weight coefficient of each target component relative to the echo signal based on the distribution of the stimulus echo comprises: Based on the distribution of the stimulus echo, obtaining the target component; A weight coefficient of each target component is obtained based on the target component and the echo interval in the echo sequence.

5. The method for calculating the diffusion sensitivity factor according to claim 4, characterized in that: Also includes: representing the target component in the form of a spin echo and a stimulation echo; The spin echo and the stimulation echo are represented by the flip angles of the corresponding radio frequency pulses in the echo sequence.

6. The method for calculating the diffusion sensitivity factor according to claim 2, characterized in that: Determining the target diffusion sensitivity factor according to the weight coefficient, the target component and the distribution of the stimulus echo includes: Calculating the diffusion sensitivity factor of each target component according to the position of the stimulus echo in the echo sequence and the distribution of the stimulus echo; Based on the weight coefficient, the diffusion sensitivity factor of each target component is weighted to obtain the target diffusion factor.

7. A magnetic resonance imaging method, characterized in that: include: Determine the diffusion coefficient based on the target diffusion sensitivity factor obtained by the diffusion sensitivity factor calculation method according to any one of claims 1 to 6; Diffusion weighted imaging is performed based on the diffusion coefficient to obtain a magnetic resonance image.

8. A magnetic resonance imaging system, characterized in that: include: A magnetic resonance scanning device for applying an echo sequence to form a radio frequency field and receiving an echo signal through a radio frequency coil; A controller, used to execute the diffusion sensitivity factor calculation method according to any one of claims 1 to 6 or the magnetic resonance imaging method according to claim 7.

9. A computer 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 diffusion sensitivity factor calculation method according to any one of claims 1 to 6 or the magnetic resonance imaging method according to claim 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the diffusion sensitivity factor calculation method according to any one of claims 1 to 6 or the magnetic resonance imaging method according to claim 7 are implemented.

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