Magnetic resonance scanning method and device, computer equipment and storage medium

Abstract

The invention relates to a magnetic resonance scanning method and device, computer equipment and a storage medium. The method comprises the following steps: acquiring a target pulse sequence; the target pulse sequence comprises a selected layer excitation pulse and a refocusing pulse pair, the refocusing pulse pair comprises a first refocusing pulse and a second refocusing pulse, and selected layer gradient directions corresponding to the first refocusing pulse and the second refocusing pulse are opposite; the target pulse sequence further comprises a first dispersed phase gradient applied before the first refocusing pulse and a second dispersed phase gradient applied after the second refocusing pulse, and the first dispersed phase gradient is different from the second dispersed phase gradient; performing imaging scanning on a target area of the to-be-scanned object based on the target pulse sequence to obtain a magnetic resonance scanning signal of the target area; and generating a scanning image of the target area according to the magnetic resonance scanning signal. Two refocusing pulses with reverse layer selection gradients are combined with a dispersed phase gradient, so that out-of-layer interference signals caused by a chemical shift effect are eliminated, and the imaging quality of a layer selection image is improved.

Description

Technical Field

[0001] The present application relates to the field of magnetic resonance technology, and in particular to a magnetic resonance scanning method, device, computer equipment and storage medium. Background Art

[0002] Magnetic resonance imaging, as a technical means of non-invasively detecting changes in human body structure or metabolism, is widely used in various clinical auxiliary detection scenarios and plays an important role.

[0003] In organic compounds, the electron cloud density around various hydrogen nuclei in different structures and positions is different, resulting in different resonance frequencies, that is, the displacement of the resonance absorption peak, which is called chemical shift. In magnetic resonance imaging, due to the different chemical structures of different substances, the resonance frequencies are different, and the frequency value of this difference is directly proportional to the field strength of the main magnetic field. In the process of magnetic resonance imaging, it is necessary to select a layer first, and then perform magnetic resonance scanning on the selected layer area. In the process of magnetic resonance scanning of the selected layer area, the layer selection radio frequency bandwidth is limited, and the chemical shift phenomenon will cause the spatial position of the scanned signals of different substances to deviate, that is, the chemical shift effect. When the proton frequency difference between two substances is equal to the radio frequency bandwidth, the two will be exactly separated in the selected spatial area, that is, there is no overlapping area. Under high field strength, the chemical shift frequency increases. If the radio frequency bandwidth remains unchanged, the spatial non-overlap degree of the scan signals corresponding to different substances collected will increase compared to low field.

[0004] When using traditional methods for layer-selected imaging, it is easy to superimpose signals from materials in different spatial regions onto the image corresponding to the current layer selection, thus causing problems such as confusion of different components and poor imaging quality in the image corresponding to the current layer selection. Summary of the invention

[0005] Based on this, it is necessary to provide a magnetic resonance scanning method, device, computer equipment, computer-readable storage medium and computer program product that can avoid the signals of materials in different selected layer spaces from being superimposed on the image corresponding to the current selected layer space during selected layer imaging, solve the problem of material composition confusion, and improve the quality of selected layer imaging in response to the above-mentioned technical problems.

[0006] In a first aspect, the present application provides a magnetic resonance scanning method. The method comprises:

[0007] Acquire a target pulse sequence; the target pulse sequence includes a layer selection excitation pulse and a refocusing pulse pair, the refocusing pulse pair includes a first refocusing pulse and a second refocusing pulse, and the layer selection gradients corresponding to the first refocusing pulse and the second refocusing pulse are in opposite directions; the target pulse sequence also includes a first dephasing gradient applied before the first refocusing pulse, and a second dephasing gradient applied after the second refocusing pulse, and the first dephasing gradient is different from the second dephasing gradient;

[0008] Performing imaging scanning on a target area of ​​the object to be scanned based on a target pulse sequence to obtain a magnetic resonance scanning signal of the target area;

[0009] A scan image of the target area is generated based on the magnetic resonance scanning signal.

[0010] In one embodiment, acquiring a target pulse sequence includes:

[0011] Acquire an initial pulse sequence; the initial pulse sequence includes a layer selection excitation pulse and an initial refocusing pulse;

[0012] generating a refocusing pulse pair corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse;

[0013] generating a first dephasing gradient and a second dephasing gradient according to time information of the refocusing pulse pair;

[0014] A target pulse sequence is generated based on the layer-selective excitation pulse, the focusing pulse pair, the first dephasing gradient and the second dephasing gradient.

[0015] In one embodiment, generating a refocusing pulse pair corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse includes:

[0016] Obtaining the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse;

[0017] Generate a target refocusing pulse corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse; the layer selection gradient of the target refocusing pulse is opposite to the layer selection gradient of the initial refocusing pulse, and the target refocusing pulse is adjacent to the initial refocusing pulse in time series;

[0018] Based on the initial refocusing pulse and the target refocusing pulse, a refocusing pulse pair corresponding to the initial refocusing pulse is generated.

[0019] In one embodiment, generating a first dephasing gradient and a second dephasing gradient according to time information of the refocusing pulse pair includes:

[0020] Obtaining the start time information and the end time information of the focusing pulse pair;

[0021] A first dephasing gradient is generated before the start time information of the refocusing pulse pair, and a second dephasing gradient is generated after the end time information of the refocusing pulse pair; the first dephasing gradient and the second dephasing gradient have the same amplitude and opposite directions.

[0022] In one embodiment, if the bandwidth of each focusing pulse in the focusing pulse pair is greater than a preset bandwidth threshold, imaging scanning is performed on a target area of ​​the object to be scanned based on the target pulse sequence to obtain a magnetic resonance scanning signal of the target area, including:

[0023] Performing an imaging scan on a target area of ​​the object to be scanned based on a target pulse sequence to obtain a first magnetic resonance scanning signal corresponding to a first substance in the target area and a second magnetic resonance scanning signal corresponding to a second substance in the target area; the preset bandwidth threshold is determined according to a frequency difference between a precession frequency of the first substance under a preset magnetic field and a precession frequency of the second substance under the preset magnetic field;

[0024] Accordingly, a scan image of the target area is generated according to the magnetic resonance scan signal, including:

[0025] A scan image of the target area is generated according to a first magnetic resonance scan signal corresponding to the first substance and a second magnetic resonance scan signal corresponding to the second substance.

[0026] In one embodiment, imaging scanning is performed on a target area of ​​a subject to be scanned based on a target pulse sequence to obtain a first magnetic resonance scanning signal corresponding to a first substance in the target area and a second magnetic resonance scanning signal corresponding to a second substance in the target area, including:

[0027] Based on the focusing pulse pair in the target pulse sequence, a focusing operation is performed on the target area of ​​the scanned object to obtain a first focusing result corresponding to the first substance in the target area and a second focusing result corresponding to the second substance in the target area and the offset area; the offset area is an area obtained by performing a spatial position offset based on the target area during the focusing operation;

[0028] generating a first magnetic resonance scanning signal corresponding to the first substance according to a first aggregation result corresponding to the first substance;

[0029] Based on the first dephasing gradient and the second dephasing gradient, a dephasing operation is performed on the invalid refocusing results in the second refocusing results to obtain a second magnetic resonance scanning signal corresponding to the second substance; the invalid refocusing results include the refocusing results of the second substance in the target area after a refocusing operation is performed on the refocusing pulse pair, and the refocusing results of the second substance in the offset area.

[0030] In one embodiment, if the bandwidth of each focusing pulse in the focusing pulse pair is less than or equal to a preset bandwidth threshold, imaging scanning is performed on a target area of ​​the object to be scanned based on the target pulse sequence to obtain a magnetic resonance scanning signal of the target area, including:

[0031] Performing an imaging scan on a target area of ​​the object to be scanned based on a target pulse sequence to obtain a third magnetic resonance scanning signal corresponding to a first substance in the target area; the preset bandwidth threshold is determined according to a frequency difference between a precession frequency of the first substance under a preset magnetic field and a precession frequency of the second substance under the preset magnetic field;

[0032] Accordingly, a scan image of the target area is generated according to the magnetic resonance scan signal, including:

[0033] A scan image of the target area is generated according to the third magnetic resonance scan signal corresponding to the first substance.

[0034] In a second aspect, the present application also provides a magnetic resonance scanning device. The device comprises:

[0035] The acquisition module is used to acquire a target pulse sequence; the target pulse sequence includes a layer selection excitation pulse and a refocusing pulse pair, the refocusing pulse pair includes a first refocusing pulse and a second refocusing pulse, and the layer selection gradients corresponding to the first refocusing pulse and the second refocusing pulse are in opposite directions; the target pulse sequence also includes a first dephasing gradient applied before the first refocusing pulse, and a second dephasing gradient applied after the second refocusing pulse, and the first dephasing gradient is different from the second dephasing gradient.

[0036] A scanning module, used for performing imaging scanning on a target area of ​​the object to be scanned based on a target pulse sequence to obtain a magnetic resonance scanning signal of the target area;

[0037] The generating module is used to generate a scanning image of the target area according to the magnetic resonance scanning signal.

[0038] In a third aspect, the present application further provides a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the magnetic resonance scanning method in the first aspect when executing the computer program.

[0039] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the magnetic resonance scanning method in the first aspect when executed by a processor.

[0040] In a fifth aspect, the present application further provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the magnetic resonance scanning method in the first aspect are implemented.

[0041] The above-mentioned magnetic resonance scanning method, device, computer equipment, storage medium and computer program product, the computer equipment obtains a target pulse sequence; the target pulse sequence includes a layer selection excitation pulse and a refocusing pulse pair, the refocusing pulse pair includes a first refocusing pulse and a second refocusing pulse, and the layer selection gradients corresponding to the first refocusing pulse and the second refocusing pulse are in opposite directions; the target pulse sequence also includes a first dephasing gradient applied before the first refocusing pulse, and a second dephasing gradient applied after the second refocusing pulse, and the first dephasing gradient is different from the second dephasing gradient; based on the target pulse sequence, an imaging scan is performed on the target area of ​​the object to be scanned to obtain a magnetic resonance scanning signal of the target area; according to the magnetic resonance scanning signal, a scanning image of the target area is generated. That is, in the embodiment of the present application, two focusing operations are performed on the signal through two focusing pulses with opposite directions of the layer selection gradient, so as to change the offset direction of the chemical shift, and under the action of the phase dispersion gradient, the signal after the two focusing operations is retained, while the signal after the one focusing operation is eliminated; thereby, not only can the interference signals outside the layer caused by the chemical shift effect be completely eliminated, and the adverse effects of the interference signals outside the layer on the layer selection image be avoided; but also part of the interference signals within the layer can be eliminated, thereby further improving the imaging quality of the layer selection image. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A diagram showing an application environment of a magnetic resonance scanning method in one embodiment;

[0043] Figure 2 is a schematic flow chart of a magnetic resonance scanning method in one embodiment;

[0044] Figure 3 A schematic diagram of a chemical shift improvement module in one embodiment;

[0045] FIG4( a ) is a schematic diagram of chemical shift shift caused by a single polymerization in one embodiment;

[0046] FIG4( b ) is a schematic diagram of chemical shift shift caused by two polymerizations in one embodiment;

[0047] Figure 5 A diagram showing the derivation process of the signal magnetization vector of a single refocusing and a double refocusing in one embodiment;

[0048] Figure 6 is a schematic flow chart of a magnetic resonance scanning method in another embodiment;

[0049] Figure 7 is a schematic flow chart of a magnetic resonance scanning method in another embodiment;

[0050] Figure 8 is a schematic flow chart of a magnetic resonance scanning method in another embodiment;

[0051] Fig. 9 is a schematic flow chart of a magnetic resonance scanning method in another embodiment;

[0052] Fig.10 A schematic diagram of the sequence structure of a traditional diffusion sequence in one embodiment;

[0053] Fig.11 A schematic diagram of the sequence structure of an improved diffusion sequence in one embodiment;

[0054] Fig.12 is a structural block diagram of a magnetic resonance scanning device in one embodiment;

[0055] Fig.13 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0057] In organic compounds, the electron cloud density around various hydrogen nuclei in different structures and positions is different, resulting in different resonance frequencies, that is, the displacement of the resonance absorption peak, which is called chemical shift. In magnetic resonance imaging, for different substances, the precession frequency of each substance is different under the action of the main magnetic field, resulting in frequency differences between different substances; among them, water signals and fat signals are both signals with very high content in the human body, and the frequency difference between water signals and fat signals is 3.4ppm (parts per million); and the frequency difference will form a chemical shift effect, which is manifested as: when performing selective imaging, the water signals and fat signals collected in the selected layer have spatial position offsets, that is, relative to the water signals in the selected layer, part of the fat signal comes from the selected layer, and the other part comes from the adjacent selected layer of the selected layer, or even all from the adjacent selected layer of the selected layer; resulting in the fat signal in the adjacent selected layer being superimposed on the selected layer image corresponding to the selected layer.

[0058] Intuitively, the selected layer image contains fat information in adjacent layers, resulting in image confusion, which will affect the user's viewing and analysis of the selected layer image. It may be due to interference from fat in non-same layers in space, and in severe cases, the lesions may be misjudged or missed.

[0059] In addition, according to the formula Δf∝γ*B0*Δppm, Δf represents the frequency difference; γ is a constant; B0 is the intensity of the main magnetic field; Δppm is a constant, representing the fixed frequency difference between water and fat. It can be seen that as the B0 field increases, the frequency difference between the water and fat signals increases, and the chemical shift effect is enhanced, that is, the spatial position offset between the water signal and the fat signal will increase, which will cause more fat signals different from the water signal level to be superimposed on the selected layer image; for the case of ultra-high field, the chemical shift effect can be weakened by increasing the bandwidth of the RF pulse, that is, the problem of different sources of water and fat signals can be weakened; or the fat signal can be suppressed by implementing a fat suppression module.

[0060] However, the fat compression module will increase the number of radio frequencies, resulting in an increase in the Specific Absorption Ratio (SAR) value, which means that the electromagnetic radiation energy absorbed by the patient will increase, affecting the patient's health. Among them, f(t) represents the intensity value of the RF transmission field, ‖‖ represents the second norm operation, BW represents the bandwidth of the RF transmission field, and θ represents the RF pulse reversal angle that forms the RF transmission field. It can be seen that increasing the RF pulse bandwidth of the RF transmission field will lead to an increase in the specific absorption rate value, affecting the health of patients.

[0061] Based on this, an embodiment of the present application proposes a magnetic resonance scanning method, which can effectively suppress fat interference signals different from the water signal level in the selected layer space without changing the pulse bandwidth, improve the chemical shift excitation effect, and improve the imaging quality.

[0062] The magnetic resonance scanning method provided in the embodiment of the present application can be applied to Figure 1 In the application environment shown. Among them, a magnetic resonance imaging device 102 (Magnetic Resonance Imaging, referred to as MRI) is connected to a computer device 104 through a network, and the computer device 104 is used to control the magnetic resonance imaging device 102 to perform magnetic resonance scanning on the object to be scanned, so as to obtain a scanned image of the object to be scanned. The magnetic resonance scanning method can be applied to the magnetic resonance imaging device 102, and can also be applied to the computer device 104 that is communicatively connected to the magnetic resonance imaging device 102, and the embodiment of the present application does not specifically limit this.

[0063] In one embodiment, Figure 2 As shown, a magnetic resonance scanning method is provided, which is applied to Figure 1 The computer device in the example is used to illustrate, including the following steps:

[0064] Step 201, acquiring a target pulse sequence; the target pulse sequence includes a layer selection excitation pulse and a refocusing pulse pair, the refocusing pulse pair includes a first refocusing pulse and a second refocusing pulse, and the layer selection gradients corresponding to the first refocusing pulse and the second refocusing pulse are in opposite directions; the target pulse sequence also includes a first dephasing gradient applied before the first refocusing pulse, and a second dephasing gradient applied after the second refocusing pulse, and the first dephasing gradient is different from the second dephasing gradient.

[0065] Exemplarily, the target pulse sequence may be a pulse sequence determined based on the precession frequency of the water signal, so as to suppress fat interference signals at a level different from the water signal; of course, the target pulse sequence may also be a pulse sequence determined based on the precession frequency of the fat signal, so as to suppress water interference signals at a level different from the fat signal; the embodiment of the present application does not specifically limit the target pulse sequence, and it may be determined according to scanning requirements during actual application.

[0066] The following is an example of suppressing fat interference signals that are different from water signal levels.

[0067] Exemplarily, the target pulse sequence may include a layer selection excitation pulse and a refocusing pulse pair. In terms of timing, the refocusing pulse pair is arranged after the layer selection excitation pulse, that is, the layer selection excitation pulse is applied first, and then the first refocusing pulse and the second refocusing pulse in the refocusing pulse pair are applied in sequence.

[0068] refer to Figure 3 As shown, the layer selection gradients corresponding to the first refocusing pulse and the second refocusing pulse in the refocusing pulse pair are in opposite directions, and dephasing gradients of the same size and opposite directions are coordinated before and after the implementation of the refocusing pulse pair, that is, the first dephasing gradient is applied before the first refocusing pulse is applied (the black area on the left), and the second dephasing gradient is applied after the second refocusing pulse is applied (the black area on the right); the first dephasing gradient is different from the second dephasing gradient, wherein the first dephasing gradient is different from the second dephasing gradient, which may include that the two dephasing gradients are of the same size and opposite directions, or that the two dephasing gradients are of different sizes and opposite directions.

[0069] Step 202 : performing imaging scanning on a target area of ​​the object to be scanned based on a target pulse sequence to obtain a magnetic resonance scanning signal of the target area.

[0070] The layer selection excitation pulse is used to locate the target area of ​​the object to be scanned. By applying the layer selection excitation pulse to the object to be scanned, the target area of ​​the object to be scanned can be located and imaging scanning can be performed on the target area of ​​the object to be scanned.

[0071] Exemplarily, when the target pulse sequence is a pulse sequence determined based on the precession frequency of the water signal to suppress fat interference signals different from the water signal level, the magnetic resonance scanning signal of the target area includes the water signal within the target area and the fat signal within a partial area of ​​the target area.

[0072] Referring to FIG4(a), when the pulse sequence includes only a layer-selective excitation pulse and a single focusing pulse, the water signal and the fat signal are respectively focused at different spatial positions, that is, the acquired magnetic resonance scanning signal includes the target area, such as the water signal in the area (a1-a2) surrounded by the solid line in FIG4(a), and the area after the target area is offset, such as the fat signal in the area (b1-b2) surrounded by the thin dotted line in FIG4(a); that is, the fat signal includes part of the fat signal (b1-a2) in the target area (i.e., the water signal level) and part of the fat signal (a2-b2) outside the target area (i.e., the water signal level).

[0073] As shown in reference figure 4(b), under the action of the target pulse sequence in the present application, that is, when the layer selection gradient of the second focusing pulse of the focusing pulse pair changes its polarity, the spatial position of the focusing fat signal is shifted to another direction, as shown in the area (c1-c2) surrounded by the thick dotted line in figure 4(b); then, combined with the action of the first dephasing gradient and the second dephasing gradient applied before and after the focusing pulse pair, the fat signals between the c1-b1 area and the c2-b2 area can be dispersed. At this time, the fat signal collected is only a part of the fat signal (b1-c2) in the target area (i.e., the water signal layer).

[0074] refer to Figure 5 As shown in FIG4(b), it shows the evolution of the magnetization vector at different positions in space under two dephasing and refocusing operations. It can be seen that after the signal has undergone two dephasing and two refocusing operations, the direction of the signal remains the same as the direction of the signal before the refocusing operation; that is, the corresponding spatial position of the signal after two 180° refocusing is the same, so the water signal a1-a2 in the plane can be effectively refocused; and for the fat signal, the two refocusings respectively stimulate different spatial positions, such as the thin dotted line enclosed area (b1-b2) and the thick dotted line enclosed area (c1-c2) in FIG4(b). Only the spatial position where the two intersect has undergone two refocusings can the signal be effectively refocused, that is, the fat signal between the b1-c2 area is effectively refocused; the signals in the remaining spatial areas, including the fat signals between the a1-b1 and c2-a2 areas in the plane, and the fat signals between the c1-a1 and a2-b2 areas outside the plane caused by the chemical shift offset effect, will be dephased.

[0075] Step 203: Generate a scan image of the target area according to the magnetic resonance scan signal.

[0076] Exemplarily, after acquiring the magnetic resonance signal, the computer device can perform image reconstruction based on the magnetic resonance signal to generate a scan image corresponding to the target area; that is, by performing image reconstruction on the water signal in the target area and part of the fat signal in the target area, a scan image of the target area is generated.

[0077] In the above-mentioned magnetic resonance scanning method, the computer device acquires a target pulse sequence; the target pulse sequence includes a layer selection excitation pulse and a refocusing pulse pair, the refocusing pulse pair includes a first refocusing pulse and a second refocusing pulse, and the layer selection gradients corresponding to the first refocusing pulse and the second refocusing pulse are opposite in direction; the target pulse sequence also includes a first dephasing gradient applied before the first refocusing pulse, and a second dephasing gradient applied after the second refocusing pulse, and the first dephasing gradient is different from the second dephasing gradient; based on the target pulse sequence, the target area of ​​the object to be scanned is imaged and scanned to obtain a magnetic resonance scanning signal of the target area; according to the magnetic resonance scanning signal, a scanning image of the target area is generated. That is, in the embodiment of the present application, two refocusing pulses with mutually opposite layer selection gradients are used to perform two refocusing operations on the signal, so as to change the offset direction of the chemical shift, and under the action of the dephasing gradient, the signal after the two refocusing operations is retained, while the signal after the one refocusing operation is eliminated; thereby, not only can the interference signal outside the layer caused by the chemical shift effect be completely eliminated, and the adverse effect of the interference signal outside the layer on the layer selection image can be avoided; but also part of the interference signal within the layer can be eliminated, so as to further improve the imaging quality of the layer selection image.

[0078] Figure 6 FIG. 1 is a flow chart of a magnetic resonance scanning method in another embodiment. This embodiment relates to an optional implementation process of obtaining a target pulse sequence. Based on the above embodiment, Figure 6 As shown, the above step 201 includes:

[0079] Step 601, obtaining an initial pulse sequence; the initial pulse sequence includes a layer selection excitation pulse and an initial refocusing pulse.

[0080] The initial pulse sequence may be a pulse sequence determined according to the scanning requirements of the object to be scanned. The initial pulse sequence includes a single refocusing pulse, that is, when periodic scanning is performed based on the initial pulse sequence, the initial pulse sequence corresponding to one scanning cycle includes a layer selection excitation pulse and a single initial refocusing pulse, that is, only one signal refocusing operation is performed in one scanning cycle.

[0081] Step 602: Generate a refocusing pulse pair corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse.

[0082] Exemplarily, the computer device can first determine a target refocusing pulse that is opposite to the layer selection gradient of the initial refocusing pulse based on the layer selection gradient corresponding to the initial refocusing pulse, and then determine the time node for applying the target refocusing pulse based on the time information of the initial refocusing pulse, that is, the time node for applying the initial refocusing pulse, so as to obtain the time information corresponding to the target refocusing pulse; further, based on the layer selection gradient of the initial refocusing pulse, the time information of the initial refocusing pulse, the layer selection gradient of the target refocusing pulse and the time information of the target refocusing pulse, a refocusing pulse pair corresponding to the initial refocusing pulse is generated.

[0083] In one implementation, after acquiring the initial pulse sequence, the computer device can obtain the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse from the initial pulse sequence; then, based on the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse, generate a target refocusing pulse corresponding to the initial refocusing pulse; further, based on the initial refocusing pulse and the target refocusing pulse, generate a refocusing pulse pair corresponding to the initial refocusing pulse; wherein the layer selection gradient of the target refocusing pulse is opposite to the direction of the layer selection gradient of the initial refocusing pulse, and the target refocusing pulse is adjacent to the initial refocusing pulse in the time series; optionally, the target refocusing pulse can be set before the initial refocusing pulse, or after the initial refocusing pulse; the initial refocusing pulse and the target refocusing pulse can be separated by a certain time length, or the second refocusing pulse can be directly applied after the first refocusing pulse is applied.

[0084] Step 603: Generate a first dephasing gradient and a second dephasing gradient according to the time information of the refocusing pulse pair.

[0085] In the embodiment of the present application, for the refocusing pulse pair, it is necessary to apply dephasing gradients before and after the refocusing pulse pair, that is, a first dephasing gradient needs to be applied before the first refocusing pulse, and a second dephasing gradient needs to be applied after the second refocusing pulse.

[0086] Then, after determining the re-focusing pulse pair based on the initial pulse sequence, the computer device can determine the application node of the first de-phase gradient and the application node of the second de-phase gradient based on the start application node and the end application node of the re-focusing pulse pair, and then add the first de-phase gradient at the application node of the first de-phase gradient, and add the second de-phase gradient at the application node of the second de-phase gradient; wherein the amplitudes of the first de-phase gradient and the second de-phase gradient are the same, and the directions of the first de-phase gradient and the second de-phase gradient are opposite.

[0087] Exemplarily, the computer device can first obtain the start time information and the end time information of the refocusing pulse pair; then, generate a first dephasing gradient before the start time information of the refocusing pulse pair, and generate a second dephasing gradient with the same amplitude and opposite direction as the first dephasing gradient after the end time information of the refocusing pulse pair.

[0088] Step 604: Generate a target pulse sequence based on the layer selection excitation pulse, the focusing pulse pair, the first dephasing gradient, and the second dephasing gradient.

[0089] The refocusing pulse pair includes a first refocusing pulse and a second refocusing pulse; when the first refocusing pulse is an initial refocusing pulse, the second refocusing pulse is a target refocusing pulse; when the first refocusing pulse is a target refocusing pulse, the second refocusing pulse is an initial refocusing pulse.

[0090] Exemplarily, the computer device may sequentially form a target pulse sequence having a certain time sequence according to the layer selection excitation pulse, the first dephasing gradient, the first refocusing pulse, the second refocusing pulse and the second dephasing gradient.

[0091] In this embodiment, the computer device obtains an initial pulse sequence including a layer selection excitation pulse and an initial refocusing pulse, and then generates a refocusing pulse pair corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse, and generates a first dephasing gradient and a second dephasing gradient according to the time information of the refocusing pulse pair; further, based on the layer selection excitation pulse, the refocusing pulse pair, the first dephasing gradient and the second dephasing gradient, a target pulse sequence is generated; thereby, the target pulse sequence is automatically generated by analyzing the initial pulse sequence, thereby improving the generation efficiency of the pulse sequence.

[0092] In one embodiment, the chemical shift offset effect can be weakened by increasing the pulse bandwidth; that is, the wider the bandwidth, the smaller the spatial offset of the fat signal relative to the water signal. After two reverse convergences in the embodiment of the present application, the more effective fat signals are converged, that is, the larger the spatial range between the overlapping areas b1-c2 of the two offsets. On the contrary, if the pulse bandwidth is reduced, the narrower the bandwidth, the stronger the chemical shift offset effect, and the larger the spatial offset of the fat signal relative to the water signal; when the spatial offset is greater than or equal to one-half of the water signal selection space, that is, when the spatial offset of the fat signal relative to the water signal reaches half or more of the water signal selection space, there will be no overlapping area between the fat signal spatial ranges b1-b2 and c1-c2 caused by the chemical shift offset effect; at this time, no fat signal will be collected, and the interference of all fat signals in the water signal layer will be removed, and only the water signal in the selection space will be collected.

[0093] Based on this, the critical bandwidth value can be determined according to the size of the water signal layer selection space as the preset bandwidth threshold; when the bandwidth of each refocusing pulse in the refocusing pulse pair is greater than the preset bandwidth threshold, both the water signal and part of the fat signal can be collected; when the bandwidth of each refocusing pulse in the refocusing pulse pair is less than or equal to the preset bandwidth threshold, the fat interference signal can be completely eliminated and only the water signal in the selected layer space can be collected.

[0094] The above two situations will be described in detail below.

[0095] The first case: Figure 7 As shown, in the case where the bandwidth of each refocusing pulse in the refocusing pulse pair is greater than a preset bandwidth threshold, the above step 202 may include:

[0096] Step 701 : performing imaging scanning on a target region of a scanned object based on a target pulse sequence to obtain a first magnetic resonance scanning signal corresponding to a first substance in the target region and a second magnetic resonance scanning signal corresponding to a second substance in the target region.

[0097] The preset bandwidth threshold is determined according to a frequency difference between a precession frequency of the first substance under a preset magnetic field and a precession frequency of the second substance under a preset magnetic field.

[0098] Exemplarily, in the case of collecting water signals to suppress fat signals, the first substance may be a water signal and the second substance may be a fat signal; in the case of collecting fat signals to suppress water signals, the first substance may be a fat signal and the second substance may be a water signal. Of course, the first substance and the second substance may also be other types of signals in the body of the object to be scanned, such as bone signals, soft tissue signals, hematoma signals, calcification signals, air signals, etc.; the embodiments of the present application do not specifically limit the types of the first substance and the second substance.

[0099] During the actual scanning process, after determining the target pulse sequence, the computer device can control the magnetic resonance imaging device to perform magnetic resonance scanning on the object to be scanned based on the target pulse sequence, and collect magnetic resonance scanning signals of the target area of ​​the object to be scanned through the magnetic resonance imaging device; wherein the magnetic resonance scanning signal includes a first magnetic resonance scanning signal corresponding to a first substance in the target area and a second magnetic resonance scanning signal corresponding to a second substance in a partial area of ​​the target area.

[0100] Accordingly, the above step 203 includes:

[0101] Step 702 : generating a scan image of a target area according to a first magnetic resonance scan signal corresponding to the first substance and a second magnetic resonance scan signal corresponding to the second substance.

[0102] Exemplarily, when a computer device acquires a magnetic resonance scanning signal including a first magnetic resonance scanning signal corresponding to a first substance and a second magnetic resonance scanning signal corresponding to a second substance, it can perform image reconstruction on the magnetic resonance scanning signal including the first magnetic resonance scanning signal corresponding to the first substance and the second magnetic resonance scanning signal corresponding to the second substance, thereby generating a scan image of the target area.

[0103] The second case: Figure 8 As shown, in the case where the bandwidth of each refocusing pulse in the refocusing pulse pair is less than or equal to the preset bandwidth threshold, the above step 202 may include:

[0104] Step 801 : performing imaging scanning on a target region of a scanned object based on a target pulse sequence to obtain a third magnetic resonance scanning signal corresponding to a first substance in the target region.

[0105] The preset bandwidth threshold is determined according to a frequency difference between a precession frequency of the first substance under a preset magnetic field and a precession frequency of the second substance under a preset magnetic field.

[0106] In this embodiment, since the bandwidth of the refocusing pulse is less than or equal to the preset bandwidth threshold, the signal of the second substance is dispersed after two refocusings. At this time, the magnetic resonance scanning signal collected by the computer device only includes the third magnetic resonance scanning signal corresponding to the first substance in the target area, but does not include the magnetic resonance scanning signal of the second substance.

[0107] Accordingly, the above step 203 includes:

[0108] Step 802: Generate a scan image of the target area according to the third magnetic resonance scan signal corresponding to the first substance.

[0109] In this case, the computer device can perform image reconstruction based only on the third magnetic resonance scanning signal corresponding to the first substance, thereby generating a scanned image of the target area, and the scanned image does not include tissue information corresponding to the second substance, such as: the scanned image generated only based on the water signal does not include fat tissue.

[0110] In this embodiment, by controlling the bandwidth of the refocusing pulse, on the basis of eliminating the interference signals outside the plane, the interference signals within the plane can be further eliminated, or even completely eliminated. Compared with the traditional method of eliminating interference signals, that is, it is necessary to use an additional interference removal module to separate the collected mixed magnetic resonance scanning signals and then remove the separated interference signals, by using the method in the embodiment of the present application, it is only necessary to reduce the bandwidth of the refocusing pulse to below the preset bandwidth threshold to achieve complete elimination of interference signals within and outside the plane. There is no need to set up an additional interference removal module, the implementation method is simple, the processing efficiency is high, and the interference removal is more accurate.

[0111] In one embodiment, Fig. 9 As shown, the above step 701 may include:

[0112] Step 901 , based on the focusing pulse pair in the target pulse sequence, a focusing operation is performed on the target area of ​​the scanned object to obtain a first focusing result corresponding to the first material in the target area and a second focusing result corresponding to the second material in the target area and the offset area.

[0113] The offset region is a region obtained by performing spatial position offset based on the target region during the convergence operation. Referring to FIG4(b), the offset region includes the region between a2-b2 and the region between c1-a1.

[0114] Taking the first substance being a water signal and the second substance being a fat signal as an example, referring to FIG4(b), when the target area is the area between a1 and a2, after performing two focusing operations on the target area of ​​the scanned object based on the focusing pulse, the first focusing result of the collected water signal includes the water signal between a1 and a2; the focusing area of ​​the fat signal includes the area b1-b2 corresponding to the first focusing pulse, and the area c1-c2 corresponding to the second focusing pulse, that is, relative to the water signal area, the fat signal generates a single focusing between the a2-b2 and a1-c1 areas outside the water signal area and between the c2-a2 and b1-a1 areas within the water signal area, and generates a double focusing only between the b1-c2 area like the water signal.

[0115] In other words, the second refocusing result corresponding to the fat signal includes the fat signal between b1-a2 areas in the target area, the fat signal between a2-b2 areas in the offset area, the fat signal between c1-a1 areas in the offset area and the fat signal between a1-c2 areas in the target area; wherein the fat signal between b1-a2 areas and the fat signal between a2-b2 areas can be used as the fat signal between b1-b2 corresponding to the spatial position offset collected after the first refocusing operation corresponding to the first refocusing pulse; the fat signal between c1-a1 areas and the fat signal between a1-c2 areas can be used as the fat signal between c1-c2 corresponding to the spatial position offset collected after the second refocusing operation corresponding to the second refocusing pulse.

[0116] Step 902: Generate a first magnetic resonance scanning signal corresponding to the first substance according to a first polymerization result corresponding to the first substance.

[0117] Step 903: performing a dephasing operation on the invalid refocusing results in the second refocusing results based on the first dephasing gradient and the second dephasing gradient to obtain a second magnetic resonance scanning signal corresponding to the second substance.

[0118] The invalid refocusing result includes the refocusing result of the second material in the target area after a refocusing pulse performs a refocusing operation, and the refocusing result of the second material in the offset area.

[0119] Refer to the above Figure 5 As shown, after the signal has undergone two convergence operations, its direction remains consistent with the initial direction before the convergence operation (i.e., the signal direction at time t1), and the signal is effectively converged; refer to FIG4 , for the second convergence result of the fat signal, the fat signal between b1-c2 has undergone two convergence operations and can be effectively converged; while the fat signal between c1-b1 and the fat signal between c2-b2 have only undergone one convergence operation and cannot be effectively converged.

[0120] At this time, combined with the effect of the dephasing gradient, the fat signal that has only undergone one refocusing operation in the second refocusing result is dephased, that is, the fat signal between the c1-b1 region that has only undergone one refocusing operation and the fat signal between the c2-b2 region are dephased, so that only the effective fat signal between the b1-c2 region that has undergone two refocusing operations is retained, and the second magnetic resonance scanning signal of the fat signal in the target region is obtained. Exemplarily, the first dephasing gradient can be used to dephasing the fat signal between the c1-b1 region, and the second dephasing gradient can be used to dephasing the fat signal between the c2-b2 region; or the first dephasing gradient can also be used to dephasing the fat signal between the c2-b2 region, and the second dephasing gradient can also be used to dephasing the fat signal between the c1-b1 region. Thereby, the effect of suppressing the fat signal outside the plane a1-a2 is achieved, and further, the partial fat signal in the plane a1-a2 can be effectively suppressed.

[0121] In this embodiment, two focusing pulses in opposite directions are combined with two phase dispersion gradients to eliminate interference signals outside the layer, and at the same time, it can also eliminate interference signals within some layers, reduce the impact of interference signals on the scanned image, and improve the quality of the scanned image.

[0122] In one embodiment, a diffusion sequence is used as an example for explanation. The diffusion sequence is a sequence that uses the state of water molecules to perform magnetic resonance imaging. The sequence structure diagram of the diffusion sequence is as follows: Fig.10 As shown in Figure 2, it can be seen that the diffusion sequence includes a single refocusing pulse, such as Fig.10 Shown in the dashed box.

[0123] like Fig.11 As shown, it shows the diffusion sequence after the improvement by the method proposed in the embodiment of the present application; that is, the original single refocusing pulse is modified into a refocusing pulse pair, and the two refocusing pulses in the refocusing pulse pair are respectively applied with layer selection gradients in opposite directions, and dispersion gradients of the same size and opposite directions are respectively added before and after the refocusing pulse pair, so as to improve the excitation effect of chemical shift of fat in the layer and eliminate the fat interference signal outside the layer.

[0124] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0125] Based on the same inventive concept, the embodiment of the present application also provides a magnetic resonance scanning device for implementing the magnetic resonance scanning method involved above. The implementation solution provided by the device to solve the problem is similar to the implementation solution recorded in the above method, so the specific limitations in one or more magnetic resonance scanning device embodiments provided below can refer to the limitations on the magnetic resonance scanning method above, and will not be repeated here.

[0126] In one embodiment, Fig.12 As shown, a magnetic resonance scanning device is provided, including: an acquisition module 1201, a scanning module 1202 and a generation module 1203, wherein:

[0127] An acquisition module 1201 is used to acquire a target pulse sequence; the target pulse sequence includes a layer selection excitation pulse and a refocusing pulse pair, the refocusing pulse pair includes a first refocusing pulse and a second refocusing pulse, and the layer selection gradients corresponding to the first refocusing pulse and the second refocusing pulse are in opposite directions; the target pulse sequence also includes a first dephasing gradient applied before the first refocusing pulse, and a second dephasing gradient applied after the second refocusing pulse, and the first dephasing gradient is different from the second dephasing gradient.

[0128] The scanning module 1202 is used to perform imaging scanning on a target area of ​​the object to be scanned based on a target pulse sequence to obtain a magnetic resonance scanning signal of the target area.

[0129] The generating module 1203 is used to generate a scan image of the target area according to the magnetic resonance scanning signal.

[0130] In one embodiment, the acquisition module 1201 includes a first acquisition submodule, a first generation submodule, a second generation submodule and a third generation submodule; wherein,

[0131] The first acquisition submodule is used to acquire an initial pulse sequence; the initial pulse sequence includes a layer selection excitation pulse and an initial refocusing pulse;

[0132] A first generating submodule is used to generate a refocusing pulse pair corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse;

[0133] A second generating submodule, used for generating a first dephasing gradient and a second dephasing gradient according to time information of the refocusing pulse pair;

[0134] The third generation submodule is used to generate a target pulse sequence based on the layer selection excitation pulse, the refocusing pulse pair, the first dephasing gradient and the second dephasing gradient.

[0135] In one embodiment, the first generation submodule includes a first acquisition unit, a first generation unit, and a second generation unit; wherein,

[0136] A first acquisition unit is used to acquire the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse;

[0137] A first generating unit is used to generate a target refocusing pulse corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse; the layer selection gradient of the target refocusing pulse is opposite to the layer selection gradient of the initial refocusing pulse, and the target refocusing pulse is adjacent to the initial refocusing pulse in time series;

[0138] The second generating unit is used to generate a refocusing pulse pair corresponding to the initial refocusing pulse based on the initial refocusing pulse and the target refocusing pulse.

[0139] In one embodiment, the second generation submodule includes a second acquisition unit and a third generation unit; wherein,

[0140] A second acquisition unit, used to acquire the start time information and the end time information of the focusing pulse pair;

[0141] The third generating unit is used to generate a first dephasing gradient before the start time information of the refocusing pulse pair, and to generate a second dephasing gradient after the end time information of the refocusing pulse pair; the amplitude of the first dephasing gradient is the same as that of the second dephasing gradient, and the directions of the first dephasing gradient and the second dephasing gradient are opposite.

[0142] In one of the embodiments, if the bandwidth of each refocusing pulse in the refocusing pulse pair is greater than a preset bandwidth threshold, the scanning module 1202 includes a second acquisition submodule;

[0143] a second acquisition submodule, configured to perform imaging scanning on a target area of ​​the object to be scanned based on a target pulse sequence, and obtain a first magnetic resonance scanning signal corresponding to a first substance in the target area and a second magnetic resonance scanning signal corresponding to a second substance in the target area; the preset bandwidth threshold is determined according to a frequency difference between a precession frequency of the first substance under a preset magnetic field and a precession frequency of the second substance under the preset magnetic field;

[0144] Accordingly, the generating module 1203 is used to generate a scan image of the target area according to the first magnetic resonance scanning signal corresponding to the first substance and the second magnetic resonance scanning signal corresponding to the second substance.

[0145] In one embodiment, the second acquisition submodule includes a third acquisition unit, a fourth generation unit and a fourth acquisition unit; wherein,

[0146] A third acquisition unit is used to perform a focusing operation on a target area of ​​the scanned object based on the focusing pulse pair in the target pulse sequence, and obtain a first focusing result corresponding to a first substance in the target area, and a second focusing result corresponding to a second substance in the target area and an offset area; the offset area is an area obtained by performing a spatial position offset based on the target area during the focusing operation;

[0147] A fourth generating unit, configured to generate a first magnetic resonance scanning signal corresponding to the first substance according to a first polymerization result corresponding to the first substance;

[0148] The fourth acquisition unit is used to perform a dephasing operation on the invalid refocusing results in the second refocusing results based on the first dephasing gradient and the second dephasing gradient to obtain a second magnetic resonance scanning signal corresponding to the second substance; the invalid refocusing results include the refocusing results of the second substance in the target area after a refocusing operation is performed on the second substance after the refocusing pulse pair, and the refocusing results of the second substance in the offset area.

[0149] In one of the embodiments, if the bandwidth of each refocusing pulse in the refocusing pulse pair is less than or equal to a preset bandwidth threshold, the scanning module 1202 further includes a third acquisition submodule;

[0150] A third acquisition submodule is used to perform imaging scanning on a target area of ​​the object to be scanned based on a target pulse sequence to obtain a third magnetic resonance scanning signal corresponding to the first substance in the target area; the preset bandwidth threshold is determined according to a frequency difference between a precession frequency of the first substance under a preset magnetic field and a precession frequency of the second substance under the preset magnetic field;

[0151] Accordingly, the generating module 1203 is used to generate a scan image of the target area according to the third magnetic resonance scanning signal corresponding to the first substance.

[0152] Each module in the above-mentioned magnetic resonance scanning device can be implemented in whole or in part by software, hardware or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to each module.

[0153] In one embodiment, a computer device is provided. The computer device may be a control terminal connected to a magnetic resonance imaging device for communication. The internal structure diagram of the computer device may be as follows: Fig.13 As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a magnetic resonance scanning method is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0154] Those skilled in the art will understand that Fig.13 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0155] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps of the magnetic resonance scanning method in each of the above embodiments when executing the computer program.

[0156] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the magnetic resonance scanning method in the above-mentioned embodiments are implemented.

[0157] In one embodiment, a computer program product is provided, comprising a computer program, wherein when the computer program is executed by a processor, the steps of the magnetic resonance scanning method in the above-mentioned embodiments are implemented.

[0158] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0159] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0160] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0161] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A magnetic resonance scanning method, characterized in that: The method comprises: Acquire a target pulse sequence; the target pulse sequence includes a layer selection excitation pulse and a refocusing pulse pair, the refocusing pulse pair includes a first refocusing pulse and a second refocusing pulse, and the layer selection gradients corresponding to the first refocusing pulse and the second refocusing pulse are in opposite directions; the target pulse sequence also includes a first dephasing gradient applied before the first refocusing pulse, and a second dephasing gradient applied after the second refocusing pulse, and the first dephasing gradient is different from the second dephasing gradient; Performing imaging scanning on a target area of ​​the object to be scanned based on the target pulse sequence to obtain a magnetic resonance scanning signal of the target area; A scan image of the target area is generated according to the magnetic resonance scan signal.

2. The method according to claim 1, characterized in that The step of acquiring a target pulse sequence comprises: Acquire an initial pulse sequence; the initial pulse sequence includes the layer selection excitation pulse and the initial refocusing pulse; generating a refocusing pulse pair corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse; generating the first dephasing gradient and the second dephasing gradient according to the time information of the refocusing pulse pair; A target pulse sequence is generated based on the slice selection excitation pulse, the refocusing pulse pair, the first dephasing gradient, and the second dephasing gradient.

3. The method according to claim 2, characterized in that The step of generating a refocusing pulse pair corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse comprises: Acquire the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse; Generate a target refocusing pulse corresponding to the initial refocusing pulse according to the layer selection gradient corresponding to the initial refocusing pulse and the time information of the initial refocusing pulse; the layer selection gradient of the target refocusing pulse is opposite to the layer selection gradient of the initial refocusing pulse, and the target refocusing pulse is adjacent to the initial refocusing pulse in time sequence; Based on the initial refocusing pulse and the target refocusing pulse, a refocusing pulse pair corresponding to the initial refocusing pulse is generated.

4. The method according to claim 2 or 3, characterized in that: The step of generating the first dephasing gradient and the second dephasing gradient according to the time information of the refocusing pulse pair comprises: Acquiring the start time information and the end time information of the focusing pulse pair; The first dephasing gradient is generated before the start time information of the refocusing pulse pair, and the second dephasing gradient is generated after the end time information of the refocusing pulse pair; the amplitudes of the first dephasing gradient and the second dephasing gradient are the same, and the directions of the first dephasing gradient and the second dephasing gradient are opposite.

5. The method according to any one of claims 1 to 4, characterized in that: If the bandwidth of each of the refocusing pulses in the refocusing pulse pair is greater than a preset bandwidth threshold, performing imaging scanning on a target area of ​​the object to be scanned based on the target pulse sequence to obtain a magnetic resonance scanning signal of the target area includes: performing an imaging scan on a target area of ​​the object to be scanned based on the target pulse sequence, and obtaining a first magnetic resonance scanning signal corresponding to a first substance in the target area and a second magnetic resonance scanning signal corresponding to a second substance in the target area; the preset bandwidth threshold is determined according to a frequency difference between a precession frequency of the first substance under the preset magnetic field and a precession frequency of the second substance under the preset magnetic field; Accordingly, generating a scan image of the target area according to the magnetic resonance scan signal includes: A scan image of the target area is generated according to a first magnetic resonance scan signal corresponding to the first substance and a second magnetic resonance scan signal corresponding to the second substance.

6. The method according to claim 5, characterized in that The method of performing imaging scanning on a target area of ​​the object to be scanned based on the target pulse sequence to obtain a first magnetic resonance scanning signal corresponding to a first substance in the target area and a second magnetic resonance scanning signal corresponding to a second substance in the target area comprises: Based on the focusing pulse pair in the target pulse sequence, a focusing operation is performed on the target area of ​​the scanned object to obtain a first focusing result corresponding to the first substance in the target area and a second focusing result corresponding to the second substance in the target area and the offset area; the offset area is an area obtained by performing a spatial position offset based on the target area during the focusing operation; generating a first magnetic resonance scanning signal corresponding to the first substance according to a first aggregation result corresponding to the first substance; Based on the first dephasing gradient and the second dephasing gradient, a dephasing operation is performed on the invalid refocusing results in the second refocusing results to obtain a second magnetic resonance scanning signal corresponding to the second substance; the invalid refocusing results include the refocusing results of the second substance in the target area after a refocusing operation is performed on the refocusing pulse pair, and the refocusing results of the second substance in the offset area.

7. The method according to any one of claims 1 to 4, characterized in that If the bandwidth of each of the refocusing pulses in the refocusing pulse pair is less than or equal to a preset bandwidth threshold, performing imaging scanning on a target area of ​​the object to be scanned based on the target pulse sequence to obtain a magnetic resonance scanning signal of the target area includes: performing an imaging scan on a target area of ​​the object to be scanned based on the target pulse sequence, and obtaining a third magnetic resonance scanning signal corresponding to the first substance in the target area; the preset bandwidth threshold is determined according to a frequency difference between a precession frequency of the first substance under the preset magnetic field and a precession frequency of the second substance under the preset magnetic field; Accordingly, generating a scan image of the target area according to the magnetic resonance scan signal includes: A scan image of the target area is generated according to a third magnetic resonance scan signal corresponding to the first substance.

8. A magnetic resonance scanning device, characterized in that: The device comprises: An acquisition module, used for acquiring a target pulse sequence; the target pulse sequence includes a layer selection excitation pulse and a refocusing pulse pair, the refocusing pulse pair includes a first refocusing pulse and a second refocusing pulse, and the layer selection gradients corresponding to the first refocusing pulse and the second refocusing pulse are in opposite directions; the target pulse sequence also includes a first dephasing gradient applied before the first refocusing pulse, and a second dephasing gradient applied after the second refocusing pulse, and the first dephasing gradient is different from the second dephasing gradient; A scanning module, configured to perform imaging scanning on a target area of ​​the object to be scanned based on the target pulse sequence, and obtain a magnetic resonance scanning signal of the target area; A generating module is used to generate a scanning image of the target area according to the magnetic resonance scanning signal.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

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 method according to any one of claims 1 to 7 are implemented.

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