A magnetic resonance imaging method, apparatus, electronic device, and storage medium

Abstract

The application provides a magnetic resonance imaging method, device, electronic equipment and storage medium. The method comprises: acquiring a plurality of scan selected layers of a target human body; for each diffusion direction, after performing a target operation corresponding to the diffusion direction on each scan selected layer, applying a signal acquisition window to the scan selected layer to obtain an imaging signal of the scan selected layer corresponding to the diffusion direction; and based on the imaging signal of the scan selected layer corresponding to the diffusion direction, performing image reconstruction to obtain a magnetic resonance diffusion weighted image of the scan selected layer corresponding to the diffusion direction. The application can reduce the pressure on the magnetic resonance system (in the gradient power amplifier coil) by advancing the application time of the eddy current elimination gradient, and in addition, the eddy current elimination gradient in the application can also disperse the fat suppression pulse additionally applied to suppress the generation of fat signals, further reducing the interference on the acquired imaging signal, thereby greatly reducing the deformation of the diffusion weighted image.

Description

Technical Field

[0001] The present application relates to the field of magnetic resonance imaging, and in particular to a magnetic resonance imaging method, apparatus, electronic device, and storage medium. Background Art

[0002] In order to obtain a diffusion-weighted image of a certain scanning layer of the human body in a certain diffusion direction, it is necessary to apply a diffusion-weighted sequence corresponding to the diffusion direction to the scanning layer through the magnetic resonance system (including, in sequence, a 90-degree radio frequency pulse, the first diffusion-weighted gradient in the diffusion direction, a 180-degree radio frequency pulse, and the second diffusion-weighted gradient in the diffusion direction). After that, a signal acquisition window is applied to acquire the imaging signal of the scanning layer in the diffusion direction (the imaging signal of the scanning layer in the diffusion direction can then be used to reconstruct the image to obtain the diffusion-weighted image of the scanning layer in the diffusion direction). However, the (two) diffusion-weighted gradients in the diffusion direction in the diffusion-weighted sequence will generate eddy currents that interfere with the imaging signal, thereby causing the diffusion-weighted image to deform. Therefore, an additional eddy current elimination gradient is required to eliminate the above-mentioned eddy currents.

[0003] In the prior art, the eddy current elimination gradient is applied after the first diffusion-weighted gradient in the diffusion direction and before the 180-degree radio frequency pulse is applied. Doing so will also affect the application intervals between the various gradients and the various radio frequency pulses (making the application intervals very small). As a result, it is necessary to successively apply a 90-degree radio frequency pulse, the first diffusion-weighted gradient in the diffusion direction, the eddy current elimination gradient in the diffusion direction (for eliminating the eddy currents generated by the first diffusion-weighted gradient in the diffusion direction and the second diffusion-weighted gradient in the diffusion direction), the 180-degree radio frequency pulse, and the second diffusion-weighted gradient in the diffusion direction. In other words, multiple gradients need to be applied in a short period of time (in addition, the intensity of the eddy current elimination gradient is also very strong), which will put great pressure on the gradient power amplifier coil in the magnetic resonance system (the gradients are all applied by the gradient power amplifier coil). Summary of the Invention

[0004] In view of this, the purpose of the present application is to provide a magnetic resonance imaging method, device, electronic device and storage medium, which can reduce the pressure on the magnetic resonance system (the gradient amplifier coil therein) by advancing the application time of the eddy current gradient. In addition, the eddy current gradient in the present application can also break up the additional fat suppression pulses applied to suppress the generation of fat signals, further reducing the interference of the collected imaging signals, thereby greatly reducing the deformation of the diffusion-weighted image.

[0005] In a first aspect, an embodiment of the present application provides a magnetic resonance imaging method, the method comprising:

[0006] Acquire multiple scanned layers of the target human body;

[0007] For each diffusion direction, after performing a target operation corresponding to the diffusion direction on each scanning selection layer through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer to obtain an imaging signal of the scanning selection layer corresponding to the diffusion direction, wherein the target operation corresponding to the diffusion direction includes: sequentially applying a fat suppression pulse for suppressing fat signals, an eddy current gradient in the diffusion direction, a 90-degree radio frequency pulse, a first diffusion weighted gradient in the diffusion direction, a 180-degree radio frequency pulse, and a second diffusion weighted gradient in the diffusion direction to the scanning selection layer, the eddy current gradient in the diffusion direction being used to eliminate eddy currents generated by the first diffusion weighted gradient in the diffusion direction and eddy currents generated by the second diffusion weighted gradient in the diffusion direction, and the eddy current gradient in the diffusion direction being further used to eliminate a stimulated echo effect caused by the fat suppression pulse and the 90-degree radio frequency pulse, and the diffusion directions include: an X-axis direction, a Y-axis direction, and a Z-axis direction;

[0008] Image reconstruction is performed based on the imaging signal of the scan selected layer corresponding to the diffusion direction to obtain a magnetic resonance diffusion weighted image of the scan selected layer corresponding to the diffusion direction.

[0009] In one possible implementation, a time interval between a moment when a target operation corresponding to the diffusion direction is performed on a current scanning layer selection and a moment when a target operation corresponding to the diffusion direction is performed on a previous scanning layer selection is greater than or equal to a characteristic time of a first target vortex, wherein the characteristic time of the first target vortex is used to represent a time duration for an initial amplitude of the first target vortex to decay to a target amplitude, the target amplitude being 1 / e of the initial amplitude of the first target vortex, the first target vortex being a vortex generated by a first target diffusion weighted gradient, and the first target diffusion weighted gradient being the first diffusion weighted gradient in the diffusion direction applied to the previous scanning layer selection.

[0010] In a possible implementation, after performing image reconstruction based on the imaging signal of the scan selected slice corresponding to the diffusion direction to obtain the magnetic resonance diffusion weighted image of the scan selected slice corresponding to the diffusion direction, the method further includes:

[0011] Obtaining pixel values ​​of pixel points at the same coordinates in the magnetic resonance diffusion-weighted image corresponding to each diffusion direction of the scanned slice;

[0012] Perform arithmetic averaging on the pixel values ​​of each pixel at the same coordinate to obtain the average pixel value corresponding to the coordinate;

[0013] For each coordinate, the pixel value of the pixel point at the coordinate in the blank image is set to the average pixel value corresponding to the coordinate, so as to obtain a composite magnetic resonance diffusion weighted image of the scanned slice.

[0014] In a possible implementation, applying a signal acquisition window to the scanning selected layer to obtain an imaging signal of the scanning selected layer corresponding to the diffusion direction includes:

[0015] The signal acquisition window is applied to the scanning selected layer, and an imaging signal of the scanning selected layer corresponding to the diffusion direction is obtained in combination with at least one of the target technologies, wherein the target technologies include: ramp acquisition technology, parallel acceleration acquisition technology, and half-Fourier imaging technology.

[0016] In a possible implementation, the signal acquisition window is an echo planar imaging (EPI) acquisition window or a fast spin echo (FSE) acquisition window.

[0017] In a second aspect, an embodiment of the present application further provides a magnetic resonance imaging device, comprising:

[0018] A first acquisition module is used to acquire multiple scanned selected layers of the target human body;

[0019] A first processing module is configured to, for each diffusion direction, apply a signal acquisition window to each scanning selected layer after performing a target operation corresponding to the diffusion direction on each scanning selected layer through a magnetic resonance system, so as to obtain an imaging signal of the scanning selected layer corresponding to the diffusion direction, wherein the target operation corresponding to the diffusion direction includes: sequentially applying a fat suppression pulse for suppressing fat signals, an eddy current elimination gradient in the diffusion direction, a 90-degree radio frequency pulse, a first diffusion weighted gradient in the diffusion direction, a 180-degree radio frequency pulse, and a second diffusion weighted gradient in the diffusion direction to the scanning selected layer, the eddy current elimination gradient in the diffusion direction being used to eliminate eddy currents generated by the first diffusion weighted gradient in the diffusion direction and eddy currents generated by the second diffusion weighted gradient in the diffusion direction, and the eddy current elimination gradient in the diffusion direction being further used to eliminate a stimulated echo effect caused by the fat suppression pulse and the 90-degree radio frequency pulse, and the diffusion directions include: an X-axis direction, a Y-axis direction, and a Z-axis direction;

[0020] The image reconstruction module is used to perform image reconstruction based on the imaging signal of the scanning selected layer corresponding to the diffusion direction, so as to obtain a magnetic resonance diffusion weighted image of the scanning selected layer corresponding to the diffusion direction.

[0021] In one possible implementation, a time interval between a moment when a target operation corresponding to the diffusion direction is performed on a current scanning layer selection and a moment when a target operation corresponding to the diffusion direction is performed on a previous scanning layer selection is greater than or equal to a characteristic time of a first target vortex, wherein the characteristic time of the first target vortex is used to represent a time duration for an initial amplitude of the first target vortex to decay to a target amplitude, the target amplitude being 1 / e of the initial amplitude of the first target vortex, the first target vortex being a vortex generated by a first target diffusion weighted gradient, and the first target diffusion weighted gradient being the first diffusion weighted gradient in the diffusion direction applied to the previous scanning layer selection.

[0022] In a possible implementation, the device further includes:

[0023] a second acquisition module, configured to, after the image reconstruction module performs image reconstruction based on the imaging signal of the scan selected slice corresponding to the diffusion direction to obtain the magnetic resonance diffusion weighted image of the scan selected slice corresponding to the diffusion direction, acquire pixel values ​​of pixel points at the same coordinates in the magnetic resonance diffusion weighted image of the scan selected slice corresponding to each diffusion direction;

[0024] A calculation module is used to perform arithmetic averaging on the pixel values ​​of each pixel at the same coordinate to obtain the average pixel value corresponding to the coordinate;

[0025] The second processing module is used to set the pixel value of the pixel point at each coordinate in the blank image to the average pixel value corresponding to the coordinate to obtain the composite magnetic resonance diffusion weighted image of the scanned selected layer.

[0026] When the first processing module applies a signal acquisition window to the scanning selected layer to obtain an imaging signal of the scanning selected layer corresponding to the diffusion direction, the first processing module is specifically configured to:

[0027] The signal acquisition window is applied to the scanning selected layer, and an imaging signal of the scanning selected layer corresponding to the diffusion direction is obtained in combination with at least one of the target technologies, wherein the target technologies include: ramp acquisition technology, parallel acceleration acquisition technology, and half-Fourier imaging technology.

[0028] In a possible implementation, the signal acquisition window is an echo planar imaging (EPI) acquisition window or a fast spin echo (FSE) acquisition window.

[0029] In a third aspect, an embodiment of the present application further provides an electronic device comprising: a processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor. When the electronic device is running, the processor and the storage medium communicate via the bus, and the processor executes the machine-readable instructions to perform the steps of the magnetic resonance imaging method described in any one of the first aspects.

[0030] In a fourth aspect, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the magnetic resonance imaging method as described in any one of the first aspects are executed.

[0031] The embodiments of the present application provide a magnetic resonance imaging method, device, electronic device, and storage medium that can reduce the pressure on the magnetic resonance system (the gradient amplifier coil therein) by advancing the application time of the eddy current gradient. In addition, the eddy current gradient in the present application can also break up the additionally applied fat suppression pulses used to suppress the generation of fat signals, further reducing the interference with the collected imaging signals, thereby significantly reducing the deformation of the diffusion-weighted image. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A flow chart of a magnetic resonance imaging method provided by an embodiment of the present application is shown;

[0034] Figure 2 A schematic diagram of a timing of applying a diffusion weighted sequence and a signal acquisition window provided by the prior art is shown;

[0035] Figure 3 A schematic diagram of a timing sequence for applying an eddy current gradient, a diffusion weighted sequence, and a signal acquisition window provided by the prior art is shown;

[0036] Figure 4 A schematic diagram of the timing of applying a fat compression pulse, an eddy current gradient, a diffusion weighted sequence, and a signal acquisition window provided in an embodiment of the present application is shown;

[0037] Figure 5 A flow chart of another magnetic resonance imaging method provided by an embodiment of the present application is shown;

[0038] Figure 6 A schematic structural diagram of a magnetic resonance imaging device provided in an embodiment of the present application is shown;

[0039] Figure 7 A schematic structural diagram of an electronic device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of illustration and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowcharts can be implemented out of sequence, and steps without logical context can be reversed or implemented simultaneously. In addition, those skilled in the art, under the guidance of the contents of this application, can add one or more other operations to the flowchart, or remove one or more operations from the flowchart.

[0041] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0042] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0043] To facilitate understanding of this embodiment, a magnetic resonance imaging method, device, electronic device and storage medium provided in the embodiments of the present application are introduced in detail.

[0044] Reference Figure 1 FIG. 1 is a flow chart of a magnetic resonance imaging method provided in an embodiment of the present application, wherein the method comprises:

[0045] S101, obtaining multiple scanned layers of a target human body.

[0046] The target human body is located in the magnetic resonance system, and multiple scanning selection layers are parallel to each other.

[0047] S102. For each diffusion direction, after performing a target operation corresponding to the diffusion direction on each scanning selection layer through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer to obtain an imaging signal of the scanning selection layer corresponding to the diffusion direction, wherein the target operation corresponding to the diffusion direction includes: applying a fat suppression pulse for suppressing fat signals, an eddy current gradient in the diffusion direction, a 90-degree radio frequency pulse, a first diffusion weighted gradient in the diffusion direction, a 180-degree radio frequency pulse and a second diffusion weighted gradient in the diffusion direction to the scanning selection layer in sequence, the eddy current gradient in the diffusion direction is used to eliminate the eddy current generated by the first diffusion weighted gradient in the diffusion direction and the eddy current generated by the second diffusion weighted gradient in the diffusion direction, and the eddy current gradient in the diffusion direction is also used to eliminate the stimulated echo effect caused by the fat suppression pulse and the 90-degree radio frequency pulse, and the diffusion directions include: X-axis direction, Y-axis direction, and Z-axis direction.

[0048] That is, for each diffusion direction, after the target operation corresponding to the diffusion direction is performed on each scanning selection layer through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer (after the target operation corresponding to the diffusion direction is performed) to obtain the imaging signal of the scanning selection layer (after the target operation corresponding to the diffusion direction is performed) corresponding to the diffusion direction.

[0049] Compared with the prior art, in addition to advancing the application time of the eddy current gradient (by adjusting the parameters of the eddy current gradient, which include: amplitude, polarity, shape, duration, area, etc.), the eddy current gradient in the present application can also eliminate the stimulated echo effect caused by the additionally applied fat suppression pulse (the fat suppression pulse can avoid the inclusion of fat signals in the imaging signal) and the 90-degree radio frequency pulse (that is, the eddy current gradient in the diffusion direction can break up the fat suppression pulse).

[0050] Exemplarily, there are three scanning selection layers, namely scanning selection layer 1, scanning selection layer 2 and scanning selection layer 3.

[0051] Since there are three diffusion directions (X-axis direction, Y-axis direction, and Z-axis direction), (the following steps are for illustrative purposes only and are not in any particular order) after performing a target operation corresponding to the X-axis direction on scanning selection layer 1, a signal acquisition window is applied to scanning selection layer 1 to obtain an imaging signal of scanning selection layer 1 corresponding to the X-axis direction; after performing a target operation corresponding to the X-axis direction on scanning selection layer 2, a signal acquisition window is applied to scanning selection layer 2 to obtain an imaging signal of scanning selection layer 2 corresponding to the X-axis direction; after performing a target operation corresponding to the X-axis direction on scanning selection layer 3, a signal acquisition window is applied to scanning selection layer 3 to obtain an imaging signal of scanning selection layer 3 corresponding to the X-axis direction;

[0052] Similarly, after performing a target operation corresponding to the Y-axis direction on scanning selection layer 1, a signal acquisition window is applied to scanning selection layer 1 to obtain an imaging signal corresponding to the Y-axis direction of scanning selection layer 1; after performing a target operation corresponding to the Y-axis direction on scanning selection layer 2, a signal acquisition window is applied to scanning selection layer 2 to obtain an imaging signal corresponding to the Y-axis direction of scanning selection layer 2; after performing a target operation corresponding to the Y-axis direction on scanning selection layer 3, a signal acquisition window is applied to scanning selection layer 3 to obtain an imaging signal corresponding to the Y-axis direction of scanning selection layer 3;

[0053] Similarly, after performing the target operation corresponding to the Z-axis direction on scanning selection layer 1, a signal acquisition window is applied to scanning selection layer 1 to obtain the imaging signal of scanning selection layer 1 corresponding to the Z-axis direction; after performing the target operation corresponding to the Z-axis direction on scanning selection layer 2, a signal acquisition window is applied to scanning selection layer 2 to obtain the imaging signal of scanning selection layer 2 corresponding to the Z-axis direction; after performing the target operation corresponding to the Z-axis direction on scanning selection layer 3, a signal acquisition window is applied to scanning selection layer 3 to obtain the imaging signal of scanning selection layer 3 corresponding to the Z-axis direction.

[0054] It should be noted that the above steps cannot be executed synchronously (in actual situations, there is no situation where multiple magnetic resonance systems are used to simultaneously perform magnetic resonance scans in the same or different diffusion directions on the same or different scanning selection layers of a patient. Similarly, there is no situation where the same magnetic resonance system is used to simultaneously perform magnetic resonance scans in the same diffusion direction or different diffusion directions on different scanning selection layers of a patient. Also, there is no situation where the same magnetic resonance system is used to simultaneously perform magnetic resonance scans in different diffusion directions on a certain scanning selection layer of a patient). For example, it is impossible to perform a target operation corresponding to any diffusion direction on scanning selection layer 1 while performing a target operation corresponding to any diffusion direction on scanning selection layer 2 or scanning selection layer 3; and it is impossible to perform a target operation corresponding to the Y-axis direction or a target operation corresponding to the Z-axis direction on scanning selection layer 1 while performing a target operation corresponding to the X-axis direction on scanning selection layer 1.

[0055] The diffusion-weighted gradient corresponding to the diffusion direction applied to the scanning selected slice and the eddy current (in the diffusion direction) generated by the diffusion-weighted gradient applied to the scanning selected slice and the diffusion-weighted gradient corresponding to the diffusion direction have the same polarity (for example, if the polarity of the first diffusion-weighted gradient is positive, then the polarity of the eddy current generated by the first diffusion-weighted gradient is also positive) and are in the same direction (both are in the diffusion direction). In addition, the greater the amplitude of the diffusion-weighted gradient corresponding to the diffusion direction applied to the scanning selected slice, the greater the amplitude of the eddy current (in the diffusion direction) generated by the diffusion-weighted gradient applied to the scanning selected slice and the diffusion-weighted gradient is applied to the scanning selected slice. The characteristic time of the eddy current is related to the gradient power amplifier coil in the magnetic resonance system. That is, the characteristic time of the eddy current generated by the first diffusion-weighted gradient and the characteristic time of the eddy current generated by the second diffusion-weighted gradient should be the same because both are applied by the same hardware (the gradient power amplifier coil in the magnetic resonance system).

[0056] It should also be noted that, generally, the first diffusion-weighted gradient in the diffusion direction applied to the scanning selection layer and the second diffusion-weighted gradient in the diffusion direction applied to the scanning selection layer should be exactly the same (same area, same polarity, same amplitude, same duration and same shape).

[0057] The intensity (amplitude) of the eddy current gradient in the diffusion direction applied to the scanning layer selection is calculated by the following formula:

[0058]

[0059] Wherein, G3 is the amplitude of the eddy current gradient in the diffusion direction (applied to the scanning selected layer), G1 is the amplitude of the first diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer), G2 is the amplitude of the second diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer) (generally, G1 and G2 are the same), Δt is the time interval between the starting moment of the eddy current gradient in the diffusion direction (applied to the scanning selected layer) and the starting moment of the first diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer), TE is the time interval between the starting moment of the first diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer) and the center point of the signal acquisition window (applied to the scanning selected layer), TE / 2 is the time interval between the starting moment of the first diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer) and the starting moment of the second diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer), and Δt1 is the time interval between the starting moment of the first diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer) and the center point of the signal acquisition window (applied to the scanning selected layer). The time interval between the starting moment of the diffusion-weighted gradient and the center point moment of the first diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer), Δt2 is the time interval between the starting moment of the second diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer) and the center point moment of the second diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer) (generally, Δt1 and Δt2 are the same), t0 is the characteristic time of the first vortex, the first vortex is the vortex generated by the first diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer), the characteristic time of the first vortex is the time length for the initial amplitude of the first vortex to decay to the first amplitude, and the first amplitude is 1 / e of the initial amplitude of the first vortex. At the same time, t0 is also the characteristic time of the second vortex, the second vortex is the vortex generated by the second diffusion-weighted gradient in the diffusion direction (applied to the scanning selected layer), the characteristic time of the second vortex is the time length for the initial amplitude of the second vortex to decay to the second amplitude, and the second amplitude is 1 / e of the initial amplitude of the second vortex.

[0060] Reference Figure 2 FIG. 1 is a timing diagram of applying a diffusion weighted sequence and a signal acquisition window provided by the prior art. Figure 2 The method includes sequentially applying a 90-degree radio frequency pulse, a first diffusion weighted gradient in the diffusion direction, a 180-degree radio frequency pulse, a second diffusion weighted gradient in the diffusion direction, and a signal acquisition window to the scan selected layer;

[0061] Reference Figure 3 FIG. 1 is a timing diagram of applying an eddy current gradient, a diffusion weighted sequence, and a signal acquisition window provided by the prior art. Figure 3The method includes a 90-degree radio frequency pulse sequentially applied to the scan selected layer, a first diffusion weighted gradient in the diffusion direction, an eddy current gradient in the diffusion direction, a second diffusion weighted gradient in the diffusion direction, and a signal acquisition window;

[0062] Reference Figure 4 FIG. 1 is a timing diagram of applying a fat compression pulse, an eddy current gradient, a diffusion weighted sequence, and a signal acquisition window provided in an embodiment of the present application. Figure 4 The fat suppression pulse, the eddy current gradient in the diffusion direction, the 90-degree radio frequency pulse, the first diffusion weighted gradient in the diffusion direction, the 180-degree radio frequency pulse, the second diffusion weighted gradient in the diffusion direction and the signal acquisition window are sequentially applied to the scan selection layer. In addition, Figure 4 The corresponding Δt1, Δt2, TE, TE / 2 and Δt are also marked.

[0063] S103 , performing image reconstruction based on the imaging signal of the scan selected layer corresponding to the diffusion direction, to obtain a magnetic resonance diffusion weighted image of the scan selected layer corresponding to the diffusion direction.

[0064] Then, as described in step S102, the magnetic resonance diffusion weighted image corresponding to the X-axis direction of the scanning selected layer 1, the magnetic resonance diffusion weighted image corresponding to the Y-axis direction of the scanning selected layer 1, and the magnetic resonance diffusion weighted image corresponding to the Z-axis direction of the scanning selected layer 1 are obtained;

[0065] And, scanning selected layer 2 corresponds to the magnetic resonance diffusion weighted image in the X-axis direction, scanning selected layer 2 corresponds to the magnetic resonance diffusion weighted image in the Y-axis direction, and scanning selected layer 2 corresponds to the magnetic resonance diffusion weighted image in the Z-axis direction;

[0066] And, scanning selection layer 3 corresponds to the magnetic resonance diffusion weighted image in the X-axis direction, scanning selection layer 3 corresponds to the magnetic resonance diffusion weighted image in the Y-axis direction, and scanning selection layer 3 corresponds to the magnetic resonance diffusion weighted image in the Z-axis direction.

[0067] In one possible implementation, a time interval between a moment when a target operation corresponding to the diffusion direction is performed on a current scanning layer selection and a moment when a target operation corresponding to the diffusion direction is performed on a previous scanning layer selection is greater than or equal to a characteristic time of a first target vortex, wherein the characteristic time of the first target vortex is used to represent a time duration for an initial amplitude of the first target vortex to decay to a target amplitude, the target amplitude being 1 / e of the initial amplitude of the first target vortex, the first target vortex being a vortex generated by a first target diffusion weighted gradient, and the first target diffusion weighted gradient being the first diffusion weighted gradient in the diffusion direction applied to the previous scanning layer selection.

[0068] Preferably, step S101 may include the following steps:

[0069] S1011. After performing a target operation corresponding to the jth diffusion direction on the i-th scanning selected layer through the magnetic resonance system, applying the signal acquisition window to the i-th scanning selected layer to obtain an imaging signal of the i-th scanning selected layer corresponding to the j-th diffusion direction, wherein the initial values ​​of i and j are both 1;

[0070] As mentioned in step S101, there are three diffusion directions: X-axis, Y-axis, and Z-axis. The first diffusion direction can be any one of the X-axis, Y-axis, and Z-axis directions. The second diffusion direction can be any one of the X-axis, Y-axis, and Z-axis directions that is different from the first diffusion direction. The third diffusion direction can be any one of the X-axis, Y-axis, and Z-axis directions that is different from both the first and second diffusion directions.

[0071] For example, the first diffusion direction is the X-axis direction, the second diffusion direction is the Y-axis direction, and the third diffusion direction is the Z-axis direction.

[0072] S1012: Determine whether an imaging signal corresponding to each diffusion direction has been obtained for each scan selected slice. If so, return to step S103 to perform image reconstruction based on the imaging signal corresponding to the diffusion direction of the scan selected slice to obtain a magnetic resonance diffusion weighted image corresponding to the diffusion direction of the scan selected slice. If not, execute step S1013.

[0073] S1013. If the current value of i is less than n and the value of j is less than 3, then i and j are each incremented by 1, and step S1014 is executed, where n is the number of scanned layers; if the current value of i is less than n and the value of j is equal to 3, then i is incremented by 1, j is set to 1, and step S1014 is executed; if the current value of i is equal to n and the value of j is less than 3, then the value of i is set to 1, j is set to 1, and step S1014 is executed; if the current value of i is equal to n and the value of j is equal to 3, then the value of i is set to 1, j is set to 2, and step S1014 is executed;

[0074] S1014, determine whether n is divisible by 3, if so, execute step S1015, if not, return to step S1011;

[0075] S1015, determining whether the imaging signal corresponding to the second diffusion direction of the first scanning selected layer has been obtained, if so, executing step S1016, if not, returning to step S1011;

[0076] S1016. If the current value of i is 1 and the value of j is 2, set the value of j to 3 and return to step S1011; otherwise, directly return to step S1011.

[0077] Exemplarily, there are three scanning selection layers, namely scanning selection layer 1, scanning selection layer 2 and scanning selection layer 3 (ie, n=3).

[0078] Then, the imaging signals of the three scanning selected layers corresponding to each diffusion direction can be acquired in the following order (i.e., the first scanning selected layer is scanning selected layer 1, the second scanning selected layer is scanning selected layer 2, and the third scanning selected layer is scanning selected layer 3; the first diffusion direction is the X-axis direction, the second diffusion direction is the Y-axis direction, and the third diffusion direction is the Z-axis direction):

[0079] After performing a target operation corresponding to the X-axis direction on the scanning selection layer 1 through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer 1 to obtain an imaging signal corresponding to the X-axis direction of the scanning selection layer 1;

[0080] After performing a target operation corresponding to the Y-axis direction on the scanning selection layer 2 through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer 2 to obtain an imaging signal corresponding to the Y-axis direction of the scanning selection layer 2;

[0081] After performing a target operation corresponding to the Z-axis direction on the scanning selection layer 3 through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer 3 to obtain an imaging signal corresponding to the Z-axis direction of the scanning selection layer 3;

[0082] After performing a target operation corresponding to the Y-axis direction on the scanning selection layer 1 through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer 1 to obtain an imaging signal corresponding to the Y-axis direction of the scanning selection layer 1;

[0083] After performing a target operation corresponding to the Z-axis direction on the scanning selection layer 2 through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer 2 to obtain an imaging signal corresponding to the Z-axis direction of the scanning selection layer 2;

[0084] After performing a target operation corresponding to the X-axis direction on the scanning selection layer 3 through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer 3 to obtain an imaging signal corresponding to the X-axis direction of the scanning selection layer 3;

[0085] After performing a target operation corresponding to the Z-axis direction on the scanning selection layer 1 through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer 1 to obtain an imaging signal corresponding to the Z-axis direction of the scanning selection layer 3;

[0086] After performing a target operation corresponding to the X-axis direction on the scanning selection layer 2 through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer 2 to obtain an imaging signal corresponding to the X-axis direction of the scanning selection layer 2;

[0087] After the magnetic resonance system performs a target operation corresponding to the Y-axis direction on the scanning selection layer 3, a signal acquisition window is applied to the scanning selection layer 3 to obtain an imaging signal of the scanning selection layer 3 corresponding to the Y-axis direction.

[0088] In the present application, when the target operation corresponding to the current diffusion direction is performed on the current selected layer, although the eddy current elimination gradient of the current diffusion direction is applied to the current scanning selected layer, the diffusion weighted gradient of the current diffusion direction will still have residual tiny eddy currents after the signal acquisition window (duration) ends. If, after obtaining the imaging signal of the current scanning selected layer corresponding to the current diffusion direction by using the signal acquisition window, the target operation corresponding to the current diffusion direction is immediately performed on the next scanning selected layer, (the tiny eddy currents remaining by the diffusion weighted gradient of the current diffusion direction) will affect the imaging signal of the next scanning selected layer corresponding to the current diffusion direction, thereby causing a certain degree of deformation in the reconstructed magnetic resonance diffusion weighted image of the next scanning selected layer corresponding to the current diffusion direction. Since eddy currents in different diffusion directions will not accumulate, through the above steps (steps S1011 to S1016), the target operations corresponding to the same diffusion direction on different scanning selection layers are separated by at least the sum of the time of one target operation and the duration of a signal acquisition window (when n is a multiple of 3, the sum of the time of at least one target operation and the duration of a signal acquisition window; when n is not a multiple of 3, the sum of the time of two target operations and the duration of two signal acquisition windows. Generally, the sum of the time of one target operation and the duration of a signal acquisition window is greater than or equal to the characteristic time of the eddy current). In this way, it can be ensured that the eddy current generated by the weighted gradient of the current diffusion direction (including the first diffusion weighted gradient and the second diffusion weighted gradient) applied to the current scanning selection layer will not affect the imaging signal of another scanning selection layer corresponding to the current diffusion direction.

[0089] In addition, in the present application, since the diffusion weighted gradients of various diffusion directions are adopted alternately, the power consumption of the average gradient in a single direction is minimized.

[0090] In the prior art, imaging signals corresponding to the same diffusion direction in different scanning slices are preferentially acquired. This not only leads to accumulation of eddy currents in the same diffusion direction, but also further increases the power consumption of the gradient amplifier coil.

[0091] Reference Figure 5 FIG. 1 is a flow chart of another magnetic resonance imaging method provided by an embodiment of the present application. In one possible implementation, after performing image reconstruction based on the imaging signal of the scan selected slice corresponding to the diffusion direction to obtain the magnetic resonance diffusion weighted image of the scan selected slice corresponding to the diffusion direction, the method further includes:

[0092] S501: Obtain pixel values ​​of pixels at the same coordinates in the diffusion-weighted magnetic resonance image corresponding to each diffusion direction of the scanned slice.

[0093] Exemplarily, a certain scanning selection layer has a magnetic resonance diffusion weighted image corresponding to the X-axis direction, a magnetic resonance diffusion weighted image corresponding to the Y-axis direction, and a magnetic resonance diffusion weighted image corresponding to the Z-axis direction. Each of these three magnetic resonance diffusion weighted images includes the same number of pixels (different coordinates correspond to different pixels, and each coordinate corresponds to one pixel).

[0094] S502 : performing arithmetic averaging on the pixel values ​​of each pixel point at the same coordinate to obtain an average pixel value corresponding to the coordinate.

[0095] Taking the lower left corner coordinate as an example, in the magnetic resonance diffusion weighted image corresponding to the X-axis direction of the scan selection layer, the pixel value of the pixel point at the lower left corner coordinate is 50, in the magnetic resonance diffusion weighted image corresponding to the Y-axis direction of the scan selection layer, the pixel value of the pixel point at the lower left corner coordinate is 100, and in the magnetic resonance diffusion weighted image corresponding to the Z-axis direction of the scan selection layer, the pixel value of the pixel point at the lower left corner coordinate is 150.

[0096] Then, the average pixel value corresponding to the coordinate of the lower left corner is (50+100+150) / 3=100.

[0097] S503 . For each coordinate, set the pixel value of the pixel point at the coordinate in the blank image to the average pixel value corresponding to the coordinate, so as to obtain a composite magnetic resonance diffusion weighted image of the scanned slice.

[0098] The number of pixels of the blank image is the same as the number of pixels of the magnetic resonance diffusion weighted image corresponding to each diffusion direction of the scanned slice.

[0099] Then, in the blank image, the pixel value of the pixel at the lower left corner coordinate is 100 (the method for obtaining the pixel values ​​of the pixel points at the other coordinates is similar and will not be repeated here).

[0100] In a possible implementation, applying a signal acquisition window to the scanning selected layer to obtain an imaging signal of the scanning selected layer corresponding to the diffusion direction includes:

[0101] The signal acquisition window is applied to the scanning selected layer, and an imaging signal of the scanning selected layer corresponding to the diffusion direction is obtained in combination with at least one of the target technologies, wherein the target technologies include: ramp acquisition technology, parallel acceleration acquisition technology, and half-Fourier imaging technology.

[0102] Parallel accelerated acquisition technology and ramp acquisition technology can effectively shorten the echo interval during the acquisition of imaging signals in the signal acquisition window.

[0103] Half-Fourier imaging technology can shorten the total width of the signal acquisition window, thereby reducing the eddy current complexity during the acquisition of imaging signals in the signal acquisition window.

[0104] In a possible implementation, the signal acquisition window is an echo planar imaging (EPI) acquisition window or a fast spin echo (FSE) acquisition window.

[0105] An embodiment of the present application provides a magnetic resonance imaging method that can reduce the pressure on the magnetic resonance system (the gradient amplifier coil therein) by advancing the time of applying the eddy current gradient. In addition, the eddy current gradient in the present application can also break up the additionally applied fat suppression pulses used to suppress the generation of fat signals, further reducing the interference of the collected imaging signals, thereby significantly reducing the deformation of the diffusion-weighted image.

[0106] Based on the same inventive concept, the embodiments of the present application also provide a magnetic resonance imaging device corresponding to the magnetic resonance imaging method in the embodiments. Since the principle of solving the problem by the device in the embodiments of the present application is similar to that of the magnetic resonance imaging method in the embodiments of the present application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0107] Reference Figure 6 FIG. 1 is a schematic diagram of the structure of a magnetic resonance imaging device provided in an embodiment of the present application, wherein the device comprises:

[0108] The first acquisition module 601 is used to acquire multiple scanned selected layers of the target human body;

[0109] The first processing module 602 is configured to, for each diffusion direction, apply a signal acquisition window to each scanning selected layer after performing a target operation corresponding to the diffusion direction on each scanning selected layer through the magnetic resonance system, so as to obtain an imaging signal of the scanning selected layer corresponding to the diffusion direction, wherein the target operation corresponding to the diffusion direction includes: sequentially applying a fat suppression pulse for suppressing fat signals, an eddy current elimination gradient in the diffusion direction, a 90-degree radio frequency pulse, a first diffusion weighted gradient in the diffusion direction, a 180-degree radio frequency pulse, and a second diffusion weighted gradient in the diffusion direction to the scanning selected layer, the eddy current elimination gradient in the diffusion direction being used to eliminate eddy currents generated by the first diffusion weighted gradient in the diffusion direction and eddy currents generated by the second diffusion weighted gradient in the diffusion direction, and the eddy current elimination gradient in the diffusion direction being further used to eliminate a stimulated echo effect caused by the fat suppression pulse and the 90-degree radio frequency pulse, and the diffusion directions include: an X-axis direction, a Y-axis direction, and a Z-axis direction;

[0110] The image reconstruction module 603 is configured to perform image reconstruction based on the imaging signal of the scan selected layer corresponding to the diffusion direction, and obtain a magnetic resonance diffusion weighted image of the scan selected layer corresponding to the diffusion direction.

[0111] In one possible implementation, a time interval between a moment when a target operation corresponding to the diffusion direction is performed on a current scanning layer selection and a moment when a target operation corresponding to the diffusion direction is performed on a previous scanning layer selection is greater than or equal to a characteristic time of a first target vortex, wherein the characteristic time of the first target vortex is used to represent a time duration for an initial amplitude of the first target vortex to decay to a target amplitude, the target amplitude being 1 / e of the initial amplitude of the first target vortex, the first target vortex being a vortex generated by a first target diffusion weighted gradient, and the first target diffusion weighted gradient being the first diffusion weighted gradient in the diffusion direction applied to the previous scanning layer selection.

[0112] In a possible implementation, the device further includes:

[0113] a second acquisition module, configured to, after the image reconstruction module 603 performs image reconstruction based on the imaging signal of the scan selected layer corresponding to the diffusion direction, obtain the magnetic resonance diffusion weighted image of the scan selected layer corresponding to the diffusion direction, and then obtain pixel values ​​of pixel points at the same coordinates in the magnetic resonance diffusion weighted image of the scan selected layer corresponding to each diffusion direction;

[0114] A calculation module is used to perform arithmetic averaging on the pixel values ​​of each pixel at the same coordinate to obtain the average pixel value corresponding to the coordinate;

[0115] The second processing module is used to set the pixel value of the pixel point at each coordinate in the blank image to the average pixel value corresponding to the coordinate to obtain the composite magnetic resonance diffusion weighted image of the scanned selected layer.

[0116] When the first processing module 602 applies a signal acquisition window to the scanned selected layer to obtain the imaging signal of the scanned selected layer corresponding to the diffusion direction, it is specifically configured to:

[0117] The signal acquisition window is applied to the scanning selected layer, and an imaging signal of the scanning selected layer corresponding to the diffusion direction is obtained in combination with at least one of the target technologies, wherein the target technologies include: ramp acquisition technology, parallel acceleration acquisition technology, and half-Fourier imaging technology.

[0118] In a possible implementation, the signal acquisition window is an echo planar imaging (EPI) acquisition window or a fast spin echo (FSE) acquisition window.

[0119] An embodiment of the present application provides a magnetic resonance imaging device that can reduce the pressure on the magnetic resonance system (the gradient amplifier coil therein) by advancing the time of applying the eddy current gradient. In addition, the eddy current gradient in the present application can also break up the additionally applied fat suppression pulses used to suppress the generation of fat signals, further reducing the interference with the collected imaging signals, thereby significantly reducing the deformation of the diffusion-weighted image.

[0120] Reference Figure 7 As shown, an electronic device 700 provided in an embodiment of the present application includes: a processor 701, a memory 702 and a bus, wherein the memory 702 stores machine-readable instructions executable by the processor 701. When the electronic device is running, the processor 701 communicates with the memory 702 via the bus, and the processor 701 executes the machine-readable instructions to perform the steps of the magnetic resonance imaging method as described above.

[0121] Specifically, the memory 702 and the processor 701 can be general-purpose memories and processors, which are not specifically limited here. When the processor 701 runs the computer program stored in the memory 702, the magnetic resonance imaging method can be executed.

[0122] Corresponding to the above-mentioned magnetic resonance imaging method, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned magnetic resonance imaging method are executed.

[0123] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can refer to the corresponding process in the method embodiment, and will not be repeated in this application. In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0124] The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical units, that is, they may be located in one place or distributed across multiple network elements. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0125] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0126] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

[0127] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A magnetic resonance imaging method, characterized in that: The method comprises: Acquire multiple scanned layers of the target human body; For each diffusion direction, after performing a target operation corresponding to the diffusion direction on each scanning selection layer through the magnetic resonance system, a signal acquisition window is applied to the scanning selection layer to obtain an imaging signal of the scanning selection layer corresponding to the diffusion direction, wherein the target operation corresponding to the diffusion direction includes: sequentially applying a fat suppression pulse for suppressing fat signals, an eddy current gradient in the diffusion direction, a 90-degree radio frequency pulse, a first diffusion weighted gradient in the diffusion direction, a 180-degree radio frequency pulse, and a second diffusion weighted gradient in the diffusion direction to the scanning selection layer, the eddy current gradient in the diffusion direction being used to eliminate eddy currents generated by the first diffusion weighted gradient in the diffusion direction and eddy currents generated by the second diffusion weighted gradient in the diffusion direction, and the eddy current gradient in the diffusion direction being further used to eliminate a stimulated echo effect caused by the fat suppression pulse and the 90-degree radio frequency pulse, and the diffusion directions include: an X-axis direction, a Y-axis direction, and a Z-axis direction; The first diffusion-weighted gradient in the diffusion direction applied to the scan selected slice and the second diffusion-weighted gradient in the diffusion direction applied to the scan selected slice have the same area, polarity, amplitude, duration, and shape; the fat suppression pulse can prevent fat signals from being mixed in the imaging signal, and the eddy current elimination gradient in the diffusion direction can break up the fat suppression pulse; The amplitude of the eddy current gradient in the diffusion direction applied to the scanning layer selection is calculated by the following formula: ； in, is the amplitude of the anti-eddy current gradient, is the amplitude of the first diffusion weighted gradient, is the magnitude of the second diffusion weighted gradient, is the time interval between the starting time of the anti-eddy flow gradient and the starting time of the first diffusion weighted gradient, is the time interval between the start time of the first diffusion weighted gradient and the start time of the second diffusion weighted gradient, is the time interval between the start time of the first diffusion weighted gradient and the center time of the first diffusion weighted gradient, is the time interval between the start time of the second diffusion weighted gradient and the center time of the second diffusion weighted gradient, is the characteristic time of the eddy current generated by the first diffusion-weighted gradient; Image reconstruction is performed based on the imaging signal of the scan selected layer corresponding to the diffusion direction to obtain a magnetic resonance diffusion weighted image of the scan selected layer corresponding to the diffusion direction.

2. The magnetic resonance imaging method according to claim 1, wherein The time interval between the moment when the target operation corresponding to the diffusion direction is performed on the current scanning layer selection and the moment when the target operation corresponding to the diffusion direction is performed on the previous scanning layer selection is greater than or equal to the characteristic time of the first target vortex, wherein the characteristic time of the first target vortex is used to represent the time length for the initial amplitude of the first target vortex to decay to the target amplitude, and the target amplitude is the initial amplitude of the first target vortex. The first target eddy current is the eddy current generated by the first target diffusion weighted gradient, and the first target diffusion weighted gradient is the first diffusion weighted gradient of the diffusion direction applied to the previous scanning layer selection.

3. The magnetic resonance imaging method according to claim 1, wherein After performing image reconstruction based on the imaging signal of the scan selected layer corresponding to the diffusion direction to obtain a magnetic resonance diffusion weighted image of the scan selected layer corresponding to the diffusion direction, the method further includes: Obtaining pixel values ​​of pixel points at the same coordinates in the magnetic resonance diffusion-weighted image corresponding to each diffusion direction of the scanned slice; Perform arithmetic averaging on the pixel values ​​of each pixel at the same coordinate to obtain the average pixel value corresponding to the coordinate; For each coordinate, the pixel value of the pixel point at the coordinate in the blank image is set to the average pixel value corresponding to the coordinate, so as to obtain a composite magnetic resonance diffusion weighted image of the scanned slice.

4. The magnetic resonance imaging method according to claim 1, wherein: Applying a signal acquisition window to the scanning selected layer to obtain an imaging signal of the scanning selected layer corresponding to the diffusion direction, including: The signal acquisition window is applied to the scanning selected layer, and an imaging signal of the scanning selected layer corresponding to the diffusion direction is obtained in combination with at least one of the target technologies, wherein the target technologies include: ramp acquisition technology, parallel acceleration acquisition technology, and half-Fourier imaging technology.

5. The magnetic resonance imaging method according to claim 1, wherein: The signal acquisition window is an echo planar imaging (EPI) acquisition window or a fast spin echo (FSE) acquisition window.

6. A magnetic resonance imaging apparatus, characterized in that: The device comprises: A first acquisition module is used to acquire multiple scanned selected layers of the target human body; A first processing module is configured to, for each diffusion direction, apply a signal acquisition window to each scanning selected layer after performing a target operation corresponding to the diffusion direction on each scanning selected layer through a magnetic resonance system, so as to obtain an imaging signal of the scanning selected layer corresponding to the diffusion direction, wherein the target operation corresponding to the diffusion direction includes: sequentially applying a fat suppression pulse for suppressing fat signals, an eddy current elimination gradient in the diffusion direction, a 90-degree radio frequency pulse, a first diffusion weighted gradient in the diffusion direction, a 180-degree radio frequency pulse, and a second diffusion weighted gradient in the diffusion direction to the scanning selected layer, the eddy current elimination gradient in the diffusion direction being used to eliminate eddy currents generated by the first diffusion weighted gradient in the diffusion direction and eddy currents generated by the second diffusion weighted gradient in the diffusion direction, and the eddy current elimination gradient in the diffusion direction being further used to eliminate a stimulated echo effect caused by the fat suppression pulse and the 90-degree radio frequency pulse, and the diffusion directions include: an X-axis direction, a Y-axis direction, and a Z-axis direction; The first diffusion-weighted gradient in the diffusion direction applied to the scan selected slice and the second diffusion-weighted gradient in the diffusion direction applied to the scan selected slice have the same area, polarity, amplitude, duration, and shape; the fat suppression pulse can prevent fat signals from being mixed in the imaging signal, and the eddy current elimination gradient in the diffusion direction can break up the fat suppression pulse; The first processing module calculates the amplitude of the eddy current gradient in the diffusion direction applied to the scanning layer selection by the following formula: ； in, is the amplitude of the anti-eddy current gradient, is the amplitude of the first diffusion weighted gradient, is the magnitude of the second diffusion weighted gradient, is the time interval between the starting time of the anti-eddy flow gradient and the starting time of the first diffusion weighted gradient, is the time interval between the start time of the first diffusion weighted gradient and the start time of the second diffusion weighted gradient, is the time interval between the start time of the first diffusion weighted gradient and the center time of the first diffusion weighted gradient, is the time interval between the start time of the second diffusion weighted gradient and the center time of the second diffusion weighted gradient, is the characteristic time of the eddy current generated by the first diffusion-weighted gradient; The image reconstruction module is used to perform image reconstruction based on the imaging signal of the scanning selected layer corresponding to the diffusion direction, so as to obtain a magnetic resonance diffusion weighted image of the scanning selected layer corresponding to the diffusion direction.

7. The magnetic resonance imaging apparatus according to claim 6, wherein: The time interval between the moment when the target operation corresponding to the diffusion direction is performed on the current scanning layer selection and the moment when the target operation corresponding to the diffusion direction is performed on the previous scanning layer selection is greater than or equal to the characteristic time of the first target vortex, wherein the characteristic time of the first target vortex is used to represent the time length for the initial amplitude of the first target vortex to decay to the target amplitude, and the target amplitude is the initial amplitude of the first target vortex. The first target eddy current is the eddy current generated by the first target diffusion weighted gradient, and the first target diffusion weighted gradient is the first diffusion weighted gradient of the diffusion direction applied to the previous scanning layer selection.

8. The magnetic resonance imaging apparatus according to claim 6, wherein The device further comprises: a second acquisition module, configured to, after the image reconstruction module performs image reconstruction based on the imaging signal of the scan selected slice corresponding to the diffusion direction to obtain the magnetic resonance diffusion weighted image of the scan selected slice corresponding to the diffusion direction, acquire pixel values ​​of pixel points at the same coordinates in the magnetic resonance diffusion weighted image of the scan selected slice corresponding to each diffusion direction; A calculation module is used to perform arithmetic averaging on the pixel values ​​of each pixel at the same coordinate to obtain the average pixel value corresponding to the coordinate; The second processing module is used to set the pixel value of the pixel point at each coordinate in the blank image to the average pixel value corresponding to the coordinate to obtain the composite magnetic resonance diffusion weighted image of the scanned selected layer.

9. An electronic device, characterized in that: include: A processor, a storage medium, and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor and the storage medium communicate via the bus, and the processor executes the machine-readable instructions to perform the steps of the magnetic resonance imaging method according to any one of claims 1 to 5.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the magnetic resonance imaging method according to any one of claims 1 to 5 are executed.

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