Motion monitoring method, device and equipment for nuclear magnetic resonance scanning process

Abstract

The invention relates to the technical field of nuclear magnetic resonance imaging, and provides a motion monitoring method, device and equipment in a nuclear magnetic resonance scanning process, which not only can monitor the motion condition of a scanned object in real time in the scanning process, but also can reduce the possibility of image artifacts. Setting M insertion positions in N imaging excitation modules for the imaging layer included in the to-be-imaged sequence; at each insertion position, adding a motion monitoring excitation module for a non-imaging layer close to the imaging layer to obtain a nuclear magnetic resonance imaging adjustment sequence; and comparing the consistency degree of the latest signal formed based on the motion monitoring excitation module and the historical signal in the process of scanning the scanned object through the nuclear magnetic resonance imaging adjustment sequence so as to determine whether the scanned object moves along the direction vertical to the imaging layer in the scanning process.

Description

Technical Field

[0001] The present application relates to the technical field of nuclear magnetic resonance imaging, and in particular to a method and apparatus for motion monitoring during a nuclear magnetic resonance scanning process, a motion monitoring device during a nuclear magnetic resonance scanning process, a storage medium, and a computer program product. Background Art

[0002] Based on the nuclear magnetic resonance method, an image of a certain layer of the scanned object can be obtained. This imaging method is called nuclear magnetic resonance imaging. Specifically, through the imaging excitation module corresponding to the imaging layer (the imaging excitation module includes an excitation pulse RF and a layer selection gradient, where the layer selection gradient is located at G SS axis), excite the protons on the imaging layer of the scanned object, and then apply a phase gradient of Gy_1 (the phase gradient is located at G PE axis), the phase gradient is turned off after a period of time, and then the frequency gradient (the frequency gradient is located at G RO The signal is read from the ADC axis, and the signal read corresponds to that shown in FIG1(a) ADC axis; the signal is obtained through the phase gradient of Gy_1, and when the signal is filled into the k-space, it is filled into the ky_1 row corresponding to Gy_1 to obtain the phase encoding line of ky_1.

[0003] In the above manner, the phase gradient of Gy_2 is used to obtain the phase encoding line of ky_2; when reconstruction requires N phase encoding lines, N phase encoding lines can be obtained by using the above manner.

[0004] In the above process, the imaging excitation module is applied at least twice. If the scanned object moves in a direction perpendicular to the imaging layer between the two times the imaging excitation module is applied, the protons of the scanned object on the imaging layer are not in the same tissue layer, resulting in the phase encoding lines in the k-space not being in the same tissue layer, and the reconstructed image will have artifacts. In the example shown in Figure 1(b), the imaging layer is located in the transverse plane, and the direction perpendicular to the imaging layer is the head-to-foot direction, which can be recorded as the z-axis direction.

[0005] If the patient moves perpendicular to the imaging layer during the scanning process, it will be a waste of time to find that the reconstructed image has artifacts when the scan is finished, and it is necessary to rescan. Therefore, it is necessary to monitor the patient's motion in real time during the scanning process.

[0006] Current technology provides a real-time motion monitoring solution, which can add an imaging excitation module for the imaging layer between the imaging excitation modules 101 and 102, and perform motion monitoring based on the signal generated by the imaging excitation module; however, this solution is likely to affect the proton movement of the scanned object on the imaging layer, resulting in disturbance of the signal generated by the imaging excitation module 102, especially for steady-state sequences. If the steady state is destroyed, the reconstructed image is prone to produce artifacts. Summary of the invention

[0007] Based on this, it is necessary to provide a motion monitoring method, apparatus, motion monitoring equipment, storage medium and computer program product for an MRI scanning process so as to reduce the possibility of image artifacts while monitoring the motion of the scanned object in real time.

[0008] The present application provides a motion monitoring method for a nuclear magnetic resonance scanning process, the method comprising:

[0009] In N imaging excitation modules for the imaging layer included in the imaging sequence to be imaged, M insertion positions are set; both N and M are positive integers;

[0010] At each of the M insertion positions, a motion monitoring and excitation module for a non-imaging layer close to the imaging layer is added to obtain a nuclear magnetic resonance imaging adjustment sequence corresponding to the sequence to be imaged;

[0011] During the scanning of the scanned object through the magnetic resonance imaging adjustment sequence, the consistency between the latest signal formed based on the motion monitoring excitation module and the historical signal is compared to determine whether the scanned object moves in a direction perpendicular to the imaging layer during the scanning process based on the consistency.

[0012] The present application provides a motion monitoring device for a nuclear magnetic resonance scanning process, the device comprising:

[0013] An insertion processing unit, used to set M insertion positions in N imaging excitation modules for the imaging layer included in the sequence to be imaged; both N and M are positive integers;

[0014] A sequence adjustment unit, configured to add, at each of the M insertion positions, a motion monitoring and excitation module for a non-imaging layer close to the imaging layer, to obtain a nuclear magnetic resonance imaging adjustment sequence corresponding to the sequence to be imaged;

[0015] The motion monitoring unit is used to compare the consistency between the latest signal formed based on the motion monitoring excitation module and the historical signal during the scanning of the scanned object through the magnetic resonance imaging adjustment sequence, so as to determine whether the scanned object moves in a direction perpendicular to the imaging layer during the scanning process according to the consistency.

[0016] The present application provides a motion monitoring device for a nuclear magnetic resonance scanning process, comprising a memory and a processor, wherein the memory stores a computer program, and the processor executes the above method.

[0017] The present application provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to execute the above method.

[0018] The present application provides a computer program product, on which a computer program is stored, and the computer program is executed by a processor to perform the above method.

[0019] In the scheme provided by the present application, M insertion positions are set in the N imaging excitation modules for the imaging layer included in the sequence to be imaged; at each insertion position, a motion monitoring excitation module for the non-imaging layer close to the imaging layer is added to obtain a nuclear magnetic resonance imaging adjustment sequence; the motion monitoring excitation module is for the non-imaging layer, and when the motion monitoring is performed using the motion monitoring excitation module, it will not affect the proton motion of the scanned object on the imaging layer, and will not interfere with the signal formed based on the imaging excitation module, thereby reducing the possibility of artifacts in the reconstructed image; then, during the scanning of the scanned object through the nuclear magnetic resonance imaging adjustment sequence, the consistency between the latest signal formed based on the motion monitoring excitation module and the historical signal is compared to determine whether the scanned object moves in a direction perpendicular to the imaging layer during the scanning process, thereby performing real-time motion monitoring of the scanned object during the nuclear magnetic resonance scanning process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1( a ) is a schematic diagram of the principle of magnetic resonance imaging in one embodiment;

[0021] FIG1( b ) is a schematic diagram of a scanned object moving during a scanning process in one embodiment;

[0022] Figure 2 A schematic diagram of a flow chart of a motion monitoring method during a nuclear magnetic resonance scanning process in one embodiment;

[0023] FIG3( a ) is a schematic diagram of scanning of a single layer imaging in one embodiment;

[0024] FIG3( b ) is a schematic diagram of optional insertion positions in a single-slice nuclear magnetic resonance imaging sequence in one embodiment;

[0025] FIG4( a ) is a schematic diagram of scanning of multi-layer imaging in one embodiment;

[0026] FIG4( b ) is a schematic diagram of inserting a motion monitoring excitation module into a multi-slice nuclear magnetic resonance imaging sequence in one embodiment;

[0027] Figure 5 A schematic diagram of a magnetic resonance imaging scan sequence that can perform real-time motion monitoring and reduce image artifacts;

[0028] Figure 6 Possible implementations of the position of the non-imaging layer in the case of a single imaging layer;

[0029] Figure 7 Possible implementations of the positions of non-imaging layers in the case of multiple imaging layers;

[0030] Figure 8 A schematic diagram of the layer selection gradient and the radio frequency pulse in cooperation with each other in one embodiment;

[0031] Fig. 9 is a schematic diagram of comparing the consistency degree based on a discretized sampling point sequence in one embodiment;

[0032] Fig.10 A schematic diagram of introducing a non-imaging layer into a nuclear magnetic resonance scanning process in one embodiment;

[0033] Fig.11 A schematic diagram of the effect of applying the method provided by the present application in one embodiment;

[0034] Fig.12 is a structural block diagram of a motion monitoring device for a nuclear magnetic resonance scanning process in one embodiment;

[0035] Fig.13 FIG. 1 is a diagram showing the internal structure of a motion monitoring device during a nuclear magnetic resonance scanning process in one embodiment. DETAILED DESCRIPTION

[0036] 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.

[0037] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0038] The present application provides a motion monitoring method for a nuclear magnetic resonance scanning process, the method comprising: Figure 2 Steps shown.

[0039] Step S201 : setting M insertion positions in N imaging excitation modules for the imaging layer included in the sequence to be imaged; both N and M are positive integers.

[0040] The process of acquiring signals by MRI scanning can be briefly described as: using radio frequency pulses (RF) and slice gradient directions (corresponding to G SS axis) cooperate with each other to apply a specific magnetic field to excite the protons in the target layer of the scanned object; after the protons are excited, the phase encoding gradient direction (corresponding to G PE axis), apply a specific magnetic field, and after a period of time, turn off the magnetic field in the phase encoding gradient direction; then, apply the readout gradient direction (corresponding to G RO axis) to obtain the signal corresponding to the target layer.

[0041] The above RF, G SS , G PE and G RO The corresponding magnetic field has a specific application order, which can be illustrated by a sequence, which can be called a nuclear magnetic resonance scanning sequence; in addition, the acquisition time of the signal compared to the magnetic field application time can also be illustrated in the sequence, as shown in Figure 1(a) of the ADC axis.

[0042] The above-mentioned radio frequency pulse and slice selection gradient can be regarded as an excitation module, and the readout gradient can be regarded as a readout module.

[0043] If one wishes to observe the anatomical structure of the scanned object in the target layer, the signal corresponding to the target layer may be used to perform image reconstruction to obtain a cross-sectional image of the scanned object in the target layer. Specifically, the signal used for imaging may be filled into the K space to obtain a phase encoding line, and image reconstruction may be performed based on several phase encoding lines to obtain an image.

[0044] In the imaging scenario, the target layer can be called the imaging layer, the signal corresponding to the target layer belongs to the signal used for imaging, the nuclear magnetic resonance scanning sequence can be called the sequence to be imaged, the excitation module used for imaging can be called the imaging excitation module, and the readout module used for imaging can be called the imaging readout module.

[0045] The plane where the imaging layer is located can be: a coronal plane, a sagittal plane or a transverse plane, and the directions perpendicular to the imaging layer are: the front-to-back direction of a person (which can be recorded as the x-axis direction), the left-to-right direction of a person (which can be recorded as the y-axis direction), and the head-to-foot direction of a person (which can be recorded as the z-axis direction). In order to facilitate the introduction and understanding of the present application, the examples of the present application are all based on: the imaging layer is in the transverse plane, and the direction perpendicular to the imaging layer is the head-to-foot direction of a person (which can be recorded as the z-axis direction), as shown in Figure 1(a), Figure 1(b), etc.

[0046] When reconstructing a cross-sectional image of the scanned object in a certain imaging layer, in some cases it is necessary to use at least two imaging excitation modules to successively excite the protons of the scanned object in the imaging layer. At this time, the imaging sequence is configured to include N imaging excitation modules for the imaging layer, that is, these N imaging excitation modules are configured to excite the protons of the scanned object in the imaging layer, and N is a positive integer, and can further be a positive integer greater than or equal to 2.

[0047] If the sequence to be imaged is directly used for scanning, the problems mentioned in the background art may easily occur. Therefore, it is necessary to adjust the sequence to be imaged. The adjusted sequence is called a nuclear magnetic resonance imaging adjustment sequence.

[0048] After obtaining N imaging excitation modules for the same imaging layer, M insertion positions can be selected from the N imaging excitation modules at random, where M is a positive integer, and further can be a positive integer greater than or equal to 2.

[0049] Exemplarily, as shown in FIG3(a), if a certain imaging layer is denoted as 101, to reconstruct a cross-sectional image of the scanned object in the imaging layer 101, the six imaging excitation modules shown in FIG3(b) are required. These six imaging excitation modules are denoted as {101_1, 101_2, 101_3, 101_4, 101_5, 101_6}. These six imaging excitation modules can be used to obtain several phase encoding lines required to reconstruct the cross-sectional image of the scanned object in the imaging layer 101.

[0050] For the six imaging excitation modules {101_1, 101_2, 101_3, 101_4, 101_5, 101_6} of the imaging layer 101, there is an optional insertion position a before the first imaging excitation module 101_1, there is an optional insertion position g after the last imaging excitation module 101_6, and there is an optional insertion position between any two imaging excitation modules, such as insertion positions b, c, d, e and f; among these optional insertion positions, at least two insertion positions can be selected.

[0051] The above process of selecting the insertion position is for a single imaging layer and multiple imaging layers; in a single-layer imaging scenario, the insertion position can be directly selected using the process introduced in the above example.

[0052] In multi-layer imaging, there are multiple imaging layers, such as imaging layer 101, imaging layer 102, and imaging layer 103 shown in FIG4(a). The two imaging excitation modules for imaging layer 101 are denoted as {101_1, 101_2}, the two imaging excitation modules for imaging layer 102 are denoted as {102_1, 102_2}, and the two imaging excitation modules for imaging layer 103 are denoted as {103_1, 103_2}.

[0053] In a multi-layer imaging scenario, the insertion position can be directly selected using the process introduced in the above example, and the insertion position can be selected by considering the imaging excitation module of a certain imaging layer. For example, an arbitrary position between the imaging excitation modules 101_1 and 101_2 is determined as the insertion position, and an arbitrary insertion position after the imaging excitation module 101_2 is determined as the insertion position.

[0054] In a multi-layer imaging scenario, the insertion position can also be selected using a process introduced in another example, for example: the imaging layers 101, 102 and 103 are regarded as imaging layer minimum units, and the three consecutive imaging excitation modules for the imaging layer minimum units are regarded as imaging excitation module minimum units, for example, imaging excitation modules 101_1, 102_1 and 103_1 are regarded as imaging excitation module minimum units, and imaging excitation modules 101_2, 102_2 and 103_2 are regarded as imaging excitation module minimum units; among the determined imaging excitation module minimum units, at least two insertion positions are selected; in the example shown in FIG. 4( b), the position between the imaging excitation module minimum units {101_1, 102_1, 103_1} and the imaging excitation modules {101_2, 102_2, 103_2} is used as the insertion position, and the position after the imaging excitation modules {101_2, 102_2, 103_2} is used as the insertion position.

[0055] Step S202: adding a motion monitoring excitation module for a non-imaging layer close to the imaging layer at each of the M insertion positions to obtain a nuclear magnetic resonance imaging adjustment sequence that is consistent with the nuclear magnetic resonance imaging basic sequence.

[0056] As mentioned above, the excitation module used for imaging is called an imaging excitation module. Thus, the excitation module used for motion monitoring is called a motion monitoring excitation module. The corresponding layer of the motion monitoring excitation module is the non-imaging layer, which is used to excite the protons of the scanned object in the non-imaging layer.

[0057] In order to ensure the accuracy of motion monitoring, the non-imaging layer is close to the imaging layer. The closeness is measured based on the distance between the two in the z-axis direction. If the distance between the two in the z-axis direction does not exceed the set threshold, the two are considered to be close.

[0058] After selecting at least two insertion positions, a motion monitoring excitation module for the same non-imaging layer is added at each insertion position to obtain a nuclear magnetic resonance imaging adjustment sequence. The phase encoding gradient corresponding to the motion monitoring excitation module may not be set, so that the projection of the object in a certain direction can be directly seen.

[0059] If the phase encoding gradient corresponding to the motion monitoring excitation module can also be set, then the motion monitoring excitation module added at each insertion position (such as Figure 5 The motion monitoring module 110_1 and the motion monitoring module 110_2 shown have the same phase encoding gradients.

[0060] Step S203, during the scanning of the scanned object by adjusting the sequence of nuclear magnetic resonance imaging, the consistency between the latest signal generated by the motion monitoring excitation module and the historical signal is compared to determine whether the scanned object moves in a direction perpendicular to the imaging layer during the scanning process according to the consistency.

[0061] by Figure 5 The example shown introduces:

[0062] Reference Figure 5 The MRI adjustment sequence includes imaging excitation modules 101_1 and 101_2 for the imaging layer 101, and motion monitoring excitation modules 110_1 and 110_2 for the non-imaging layer. The application order of these excitation modules is, from first to last: imaging excitation module 101_1, motion monitoring excitation module 110_1, imaging excitation module 101_2, motion monitoring excitation module 110_2. During the scanning process, the corresponding magnetic field is applied according to this application order.

[0063] After the image excitation module 101_1 is applied, the corresponding phase encoding gradient PE is applied. After the phase encoding gradient is applied, the signal ADC_101_1 is obtained by reading the gradient RO. The signal is used for imaging, that is, for reconstructing the cross-sectional image of the scanned object in the imaging layer 101. Then, the motion monitoring excitation module 110_1 is applied. Figure 5 The exemplary motion monitoring module sets the phase encoding gradient PE, so after applying the motion monitoring excitation module 110_1, the signal ADC_110_1 is directly obtained by reading out the gradient RO, and the signal is used for motion monitoring; thus, the signal ADC_101_2 for imaging and the signal ADC_110_2 for motion monitoring are obtained in turn.

[0064] Specifically, acquiring the signal formed based on the motion monitoring excitation module may include the steps of: applying the motion monitoring readout module after applying the motion monitoring excitation module to acquire the signal formed based on the motion monitoring excitation module.

[0065] After the motion monitoring excitation module 110_1 is applied and before the next motion monitoring module is applied, the latest signal generated based on the motion monitoring excitation module is ADC_110_1. Figure 5 It can be seen from the sequence shown that ADC_110_1 is the first signal formed by the motion monitoring excitation module obtained in this scan based on the nuclear magnetic resonance imaging adjustment sequence. At this time, there is no historical signal and the consistency degree is not determined.

[0066] After applying the motion monitoring excitation module 110_2 and before applying the next motion monitoring module, the latest signal formed based on the motion monitoring excitation module is ADC_110_2, and the historical signal relative to ADC_110_2 is ADC_110_1. Compare the consistency between ADC_110_2 and ADC_110_1. If the consistency is high, it is determined that the scanned object has not undergone a large movement in the direction perpendicular to the imaging layer during the application of the imaging excitation modules 101_1 and 101_2; the basis for measuring the large movement is whether the movement will cause artifacts in the reconstructed image. If the consistency is low, it is determined that the scanned object has undergone a large movement in the direction perpendicular to the imaging layer during the application of the imaging excitation modules 101_1 and 101_2. In this case, scanning can be discontinued.

[0067] In the scheme provided by the present application, M insertion positions are set in the N imaging excitation modules for the imaging layer included in the sequence to be imaged; at each insertion position, a motion monitoring excitation module for the non-imaging layer close to the imaging layer is added to obtain a nuclear magnetic resonance imaging adjustment sequence; the motion monitoring excitation module is for the non-imaging layer, and when the motion monitoring is performed using the motion monitoring excitation module, it will not affect the proton motion of the scanned object on the imaging layer, and will not interfere with the signal formed based on the imaging excitation module, thereby reducing the possibility of artifacts in the reconstructed image; then, during the scanning of the scanned object through the nuclear magnetic resonance imaging adjustment sequence, the consistency between the latest signal formed based on the motion monitoring excitation module and the historical signal is compared to determine whether the scanned object moves in a direction perpendicular to the imaging layer during the scanning process, thereby performing real-time motion monitoring of the scanned object during the nuclear magnetic resonance scanning process.

[0068] Among them, the non-imaging layer and the imaging layer are arranged in a direction perpendicular to the imaging layer, for example, in a head-to-foot direction; the distance between the non-imaging layer and the imaging layer in a direction perpendicular to the imaging layer is less than or equal to a first set value; the first set value can be determined according to actual conditions.

[0069] The non-imaging layer can be located on either side of the imaging layer, or on both sides of the imaging layer at the same time; further, when there are multiple imaging layers, the non-imaging layer can also be located between adjacent imaging layers; when there are multiple imaging layers, when the spacing between adjacent imaging layers along the direction perpendicular to the imaging layers is greater than a second set value, further, the non-imaging layer is between adjacent imaging layers; wherein the second set value can be determined based on actual conditions.

[0070] Taking the direction perpendicular to the imaging layer as the head-to-foot direction, combined with Figure 6 The arrangement of non-imaging layers and imaging layers is introduced.

[0071] Figure 6 The relative positions of the non-imaging layer and the imaging layer are shown when there is one imaging layer. The non-imaging layer can be further divided into one and multiple for discussion:

[0072] 1. When there is one imaging layer and one non-imaging layer, Figure 6 (a) shows that the non-imaging layer is on the head-side of the imaging layer;

[0073] 2. When there is one imaging layer and two non-imaging layers, Figure 6 (b) shows that the two non-imaging layers are both on the head-side of the imaging layer;

[0074] 3. When there is one imaging layer and one non-imaging layer, Figure 6 (c) shows that the non-imaging layer is on the side of the imaging layer in the foot direction;

[0075] 4. When there is one imaging layer and two non-imaging layers, Figure 6 (d) shows that the two non-imaging layers are on the side of the imaging layer in the foot direction;

[0076] 5. When there is one imaging layer and two non-imaging layers, Figure 6 (e) shows that a non-imaging layer is on the head side of the imaging layer, and the other imaging layer is on the foot side.

[0077] Figure 7 The relative position between the non-imaging layer and the imaging layer when there are multiple imaging layers is shown. This can be discussed based on whether there is only one non-imaging layer and whether the spacing between the imaging layers is greater than a threshold:

[0078] When the spacing of the imaging layers is less than the threshold, the following situations may occur:

[0079] 1. When there are multiple imaging layers and one non-imaging layer, Figure 7 (a) shows that: the non-imaging layer is on the side of the imaging layer closest to the head; the imaging layer closest to the head is the imaging layer closest to the head among the multiple imaging layers;

[0080] 2. When there are multiple imaging layers and two non-imaging layers, Figure 7 (b) shows that the non-imaging layer is on the side closest to the imaging layer in the head direction;

[0081] 3. When there are multiple imaging layers and one non-imaging layer, Figure 7 (c) shows that: the non-imaging layer is on the side of the imaging layer closest to the foot in the direction of the foot; the imaging layer closest to the foot is the imaging layer closest to the foot among the multiple imaging layers;

[0082] 4. When there are multiple imaging layers and two non-imaging layers, Figure 7 (d) shows that the non-imaging layer is on the side of the imaging layer closest to the foot in the direction of the foot;

[0083] 5. When there are multiple imaging layers and two non-imaging layers, Figure 7 (e) shows: a non-imaging layer is on the side of the imaging layer closest to the head in the direction of the head, and another imaging layer is on the side of the imaging layer closest to the foot in the direction of the foot;

[0084] 6. When the distance between adjacent imaging layers is greater than a threshold, the non-imaging layer is between the adjacent imaging layers.

[0085] When the spacing between adjacent imaging layers along the head-to-foot direction is greater than the second set value, the following situations may be included:

[0086] 7. When there are multiple imaging layers, the distance between adjacent imaging layers in the head-to-foot direction is greater than the second set value, and there is only one non-imaging layer, Figure 7 (f) shows that the non-imaging layer is between two adjacent imaging layers;

[0087] 8. When there are multiple imaging layers, the distance between adjacent imaging layers in the head-to-foot direction is greater than the second set value, and there are two non-imaging layers, Figure 7 (g) shows: a non-imaging layer is on the side of the imaging layer closest to the head in the head direction, and another imaging layer is between two adjacent imaging layers;

[0088] 9. When there are multiple imaging layers, the distance between adjacent imaging layers in the head-to-foot direction is greater than the second set value, and there are two non-imaging layers, Figure 7 (h) shows: a non-imaging layer is on the side of the imaging layer closest to the foot in the direction of the foot, and another imaging layer is between the two adjacent imaging layers.

[0089] In the above-mentioned excitation module, the radio frequency pulse and the slice selection gradient can cooperate with each other to excite the protons in the target layer of the scanned object; specifically, the size of the slice selection gradient describes the change of the slice selection magnetic field (the magnetic field perpendicular to the z-axis, which can be recorded as Gz) at different positions along the z-axis. The larger the slice selection gradient, Figure 8 The steeper the line corresponding to Gz shown, the greater the change of the magnetic field at each position from head to toe on the z-axis; therefore, Gz can make the protons at different positions of the scanned object along the z-axis have a specific spin frequency; by applying a radio frequency pulse of a specific frequency, the protons at a certain position can be excited. If a radio frequency pulse of a specific frequency range is applied, the protons in the corresponding position range can be excited; the frequency range of the radio frequency pulse can be called the bandwidth of the radio frequency pulse.

[0090] In this case, the motion monitoring excitation module formed by the present application includes the following steps: when the size of the layer selection gradient used in the motion monitoring excitation module is determined in advance before the bandwidth of the radio frequency pulse, the method provided by the present application also includes: obtaining the position and thickness of the non-imaging layer in a direction perpendicular to the imaging layer; according to the thickness, under the layer selection gradient, determining the layer selection magnetic field range corresponding to the position; using the frequency range corresponding to the layer selection magnetic field range as the bandwidth of the radio frequency pulse used in the motion monitoring excitation module; based on the radio frequency pulse corresponding to the bandwidth and the layer selection gradient, obtaining the motion monitoring excitation module for the non-imaging layer.

[0091] In another embodiment, when the bandwidth of the RF pulse is determined in advance before the size of the layer selection gradient used by the motion monitoring excitation module, the method provided in the present application also includes: obtaining the position and thickness of the non-imaging layer in a direction perpendicular to the imaging layer; determining the size of the layer selection gradient based on the bandwidth, so that under the determined size of the layer selection gradient, the layer selection magnetic field range corresponding to the position corresponds to the thickness.

[0092] In the above embodiment, after the position and thickness of the non-imaging layer in a direction perpendicular to the imaging layer are determined, if the size of the layer selection gradient used by the motion monitoring excitation module is determined first, a corresponding method is used to determine the bandwidth of the radio frequency pulse used by the motion monitoring excitation module; if the bandwidth of the radio frequency pulse is determined first, another method is used to determine the size of the layer selection gradient used by the motion monitoring excitation module, thereby obtaining a motion monitoring excitation module for the non-imaging layer.

[0093] In one embodiment, the historical signal used for comparing the consistency with the latest signal formed based on the motion monitoring and excitation module can be: a signal formed based on any application of the motion monitoring and excitation module in the nuclear magnetic resonance imaging adjustment sequence;

[0094] Taking the magnetic resonance imaging adjustment sequence of {101_1, 110_1, 101_2, 110_2, 101_3, 110_3, 101_4, 110_4, 101_5, 110_5, 101_6, 110_6} as an example, the following is introduced:

[0095] In the MRI adjustment sequence, the motion monitoring excitation modules {101_1, 101_2, 101_3, 101_4, 101_5, 101_6} are applied sequentially, and the signal formed based on any application of the motion monitoring excitation module can be used as a historical signal to compare the consistency with the latest signal.

[0096] The historical signal used for comparing the consistency with the latest signal formed based on the motion monitoring excitation module may also be: a signal formed by the first motion monitoring excitation module applied in the nuclear magnetic resonance imaging adjustment sequence;

[0097] Taking the magnetic resonance imaging adjustment sequence of {101_1, 110_1, 101_2, 110_2, 101_3, 110_3, 101_4, 110_4, 101_5, 110_5, 101_6, 110_6} as an example, the following is introduced:

[0098] In the nuclear magnetic resonance imaging adjustment sequence, the first motion monitoring and excitation module is 110_1, and the signal generated based on the motion monitoring and excitation module 110_1 can be used as a historical signal to compare the consistency with the latest signal.

[0099] The historical signal used to compare the degree of consistency with the latest signal formed based on the motion monitoring and excitation module can also be: a signal formed based on the target motion monitoring and excitation module; the target motion monitoring and excitation module is a motion monitoring and excitation module that is applied before the motion monitoring and excitation module that forms the latest signal and is closest to the motion monitoring and excitation module that forms the latest signal in terms of application time.

[0100] Taking the magnetic resonance imaging adjustment sequence of {101_1, 110_1, 101_2, 110_2, 101_3, 110_3, 101_4, 110_4, 101_5, 110_5, 101_6, 110_6} as an example, the following is introduced:

[0101] If the latest signal obtained based on the motion monitoring excitation module is ADC_110_4 formed based on the motion monitoring excitation module 110_4, at this time, the motion monitoring excitation module applied before the motion monitoring excitation module 110_4 and the application time closest to the motion monitoring excitation module 110_4 is 110_3, and the signal ADC_110_3 formed based on the motion monitoring excitation module 110_3 is compared for consistency with the latest signal ADC_110_4.

[0102] In one embodiment, comparing the consistency between the latest signal and the historical signal formed based on the motion monitoring excitation module includes: obtaining the latest sampling point sequence in the discretized form of the latest signal; obtaining the historical sampling point sequence in the discretized form of the historical signal; and determining the consistency between the latest signal and the historical signal based on the difference between the latest sampling point sequence and the historical sampling point sequence.

[0103] After the protons in the non-imaging layer of the scanned object are excited by the motion monitoring excitation module, corresponding signals will be generated. The signals are sampled to obtain a discrete sampling point sequence.

[0104] The difference between the latest sampling point sequence and the historical sampling point sequence can be characterized by difference, correlation, sum of squares of differences, etc. If characterized by difference, a difference sequence can be obtained based on subtraction of the latest sampling point from the corresponding historical sampling point in sampling order, and the difference sequence is used to characterize the difference between the latest sampling point sequence and the historical sampling point sequence.

[0105] Take the latest signal ADC_110_4 and the historical signal ADC_110_1 as an example:

[0106] After applying the motion monitoring excitation module 110_1, signal acquisition can be performed to obtain a discrete sampling point sequence of ADC_110_1 {ADC_110_1_1, ADC_110_1_2, ADC_110_1_3, ADC_110_1_4, ADC_110_1_5, ...}; similarly, a discrete sampling point sequence of ADC_110_4 {ADC_110_4_1, ADC_110_4_2, ADC_110_4_3, ADC_110_4_4, ADC_110_4_5, ...} can be obtained.

[0107] In the sampling point sequence, each sampling point has its own corresponding sampling order; the sampling points corresponding to the same sampling order in the sampling point sequence discretized by ADC_110_1 and the sampling point sequence discretized by ADC_110_4 are subtracted, such as Fig. 9 As shown, a difference sequence is obtained, and the consistency degree between the latest signal and the historical signal is determined based on the difference sequence.

[0108] Further, if the difference sequence is used to characterize the difference between the latest sampling point sequence and the historical sampling point sequence, then the consistency between the latest signal and the historical signal is determined according to the difference, including: when one or more difference values ​​in the difference sequence are higher than a set threshold, it is determined that the consistency between the latest signal and the historical signal is low. For example, if one or three difference values ​​in the difference sequence are higher than the set threshold, it can be considered that the consistency between the latest signal and the historical signal is low.

[0109] In the above embodiment, the signal consistency degree is compared based on the signal discretization sampling point sequence to improve the processing efficiency.

[0110] In one embodiment, when the motion monitoring time resolution is to perform a comparison once for every P signals formed by the motion monitoring excitation module, the consistency between the latest signal formed by the motion monitoring excitation module and the historical signal is compared, including: when the latest signal formed by the motion monitoring excitation module is obtained, determine whether the number of signals between the latest signal and the last compared signal is P; if it is P, compare the consistency between the latest signal formed by the motion monitoring excitation module and the historical signal. The method provided by the present application also includes: if it is not P, then do not compare the consistency between the latest signal formed by the motion monitoring excitation module and the historical signal.

[0111] Reference Fig.10 , the same non-imaging layer was subjected to five motion monitoring excitations, and the acquired signals were recorded as ①②③④⑤⑥, where signal ① was the signal obtained by the first motion monitoring excitation (i.e., the signal formed based on the first motion monitoring excitation module).

[0112] If the motion monitoring time resolution is set to: perform a comparison every time a signal formed by the motion monitoring excitation module is received, then compare the degree of consistency between signals ②③④⑤⑥ and signal ①; if the motion monitoring time resolution is set to: perform a comparison every time two signals formed by the motion monitoring excitation module are received, then compare the degree of consistency between signals ③⑤ and signal ①.

[0113] In this embodiment, by adjusting the time resolution of motion monitoring, it is possible to properly balance computer processing resources and the real-time performance of motion monitoring.

[0114] The method provided in this application can be applied, but is not limited to, to the Gre_2d sequence, which is a steady-state sequence. Fig.11 (a) is the reconstructed image without motion. There are no artifacts in the image. The corresponding curve monitoring is Fig.11 (c) Fig.11The curve at the bottom in (c) is stable, and the above-mentioned movement of the scanned object is not detected; Fig.11 (b) is the reconstructed image after the above motion occurs during the scanning process. There are motion artifacts in the image, and the corresponding curve monitoring is Fig.11 (d) Fig.11 In (c), the lower curve fluctuates, and the upper curve is the monitoring alarm value. Some peaks exceed the upper curve. At this time, the MRI scan can be discontinued.

[0115] 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.

[0116] In one embodiment, Fig.12 As shown, a motion monitoring device for a nuclear magnetic resonance scanning process is provided, comprising:

[0117] The insertion processing unit 1201 is used to set M insertion positions in N imaging excitation modules for the imaging layer included in the sequence to be imaged; both N and M are positive integers;

[0118] A sequence adjustment unit 1202 is configured to add a motion monitoring excitation module for a non-imaging layer close to the imaging layer at each of the M insertion positions, so as to obtain a nuclear magnetic resonance imaging adjustment sequence corresponding to the sequence to be imaged;

[0119] The motion monitoring unit 1203 is used to compare the consistency between the latest signal formed based on the motion monitoring excitation module and the historical signal during the scanning of the scanned object through the magnetic resonance imaging adjustment sequence, so as to determine whether the scanned object moves in a direction perpendicular to the imaging layer during the scanning process according to the consistency.

[0120] In one embodiment, when the size of the layer selection gradient used by the motion monitoring excitation module is determined before the bandwidth of the radio frequency pulse, the device also includes a motion monitoring processing unit, which is used to obtain the position and thickness of the non-imaging layer in a direction perpendicular to the imaging layer; according to the thickness, under the layer selection gradient, determine the layer selection magnetic field range corresponding to the position; use the frequency range corresponding to the layer selection magnetic field range as the bandwidth of the radio frequency pulse used by the motion monitoring excitation module; and obtain the motion monitoring excitation module for the non-imaging layer based on the radio frequency pulse corresponding to the bandwidth and the layer selection gradient.

[0121] In one embodiment, when the bandwidth of the radio frequency pulse is determined before the size of the layer selection gradient used by the motion monitoring excitation module, the device also includes a motion monitoring processing unit for obtaining the position and thickness of the non-imaging layer in a direction perpendicular to the imaging layer; based on the bandwidth, the size of the layer selection gradient is determined so that under the determined size of the layer selection gradient, the layer selection magnetic field range corresponding to the position corresponds to the thickness.

[0122] In one embodiment, the distance between the non-imaging layer and the imaging layer along a direction perpendicular to the imaging layer is less than or equal to a first set value.

[0123] In one embodiment, when there are multiple imaging layers and the spacing between adjacent imaging layers along a direction perpendicular to the imaging layers is greater than a second set value, the non-imaging layer is between adjacent imaging layers.

[0124] In one embodiment, the motion monitoring processing unit is further used to apply a motion monitoring readout module after applying the motion monitoring excitation module to obtain a signal formed based on the motion monitoring excitation module.

[0125] In one embodiment, the historical signal used to compare the degree of consistency with the latest signal formed based on the motion monitoring and excitation module is: a signal formed based on the target motion monitoring and excitation module; the target motion monitoring and excitation module is a motion monitoring and excitation module that is applied before the motion monitoring and excitation module that forms the latest signal and is closest in application time to the motion monitoring and excitation module that forms the latest signal.

[0126] In one embodiment, when the motion monitoring time resolution is to perform a comparison for every P signals generated based on the motion monitoring excitation module, the motion monitoring unit 1203 is also used to determine whether the number of signals between the latest signal and the last compared signal is P when the latest signal generated based on the motion monitoring excitation module is obtained; if it is P, compare the consistency between the latest signal generated based on the motion monitoring excitation module and the historical signal; if it is not P, do not compare the consistency between the latest signal generated based on the motion monitoring excitation module and the historical signal.

[0127] In one embodiment, the motion monitoring unit 1203 is further used to obtain the latest sampling point sequence in the discretized form of the latest signal; obtain the historical sampling point sequence in the discretized form of the historical signal; and determine the degree of consistency between the latest signal and the historical signal based on the difference between the latest sampling point sequence and the historical sampling point sequence.

[0128] In one embodiment, the motion monitoring unit 1203 is further configured to determine that the consistency between the latest signal and the historical signal is low when a plurality of differences in the difference sequence are all higher than a set threshold.

[0129] For the specific definition of the motion monitoring device for the nuclear magnetic resonance scanning process, please refer to the definition of the motion monitoring method for the nuclear magnetic resonance scanning process in the above text, which will not be repeated here. Each module in the above-mentioned motion monitoring device for the nuclear magnetic resonance scanning process can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the motion monitoring device for the nuclear magnetic resonance scanning process in the form of hardware, or can be stored in the memory of the motion monitoring device for the nuclear magnetic resonance scanning process in the form of software, so that the processor can call and execute the operations corresponding to the above-mentioned modules.

[0130] In one embodiment, a motion monitoring device for a nuclear magnetic resonance scanning process is provided, and its internal structure diagram can be shown as follows: Fig.13As shown. The motion monitoring device for the nuclear magnetic resonance scanning process includes a processor, a memory and a network interface connected through a system bus. Among them, the processor of the motion monitoring device for the nuclear magnetic resonance scanning process is used to provide computing and control capabilities. The memory of the motion monitoring device for the nuclear magnetic resonance scanning process includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the motion monitoring device for the nuclear magnetic resonance scanning process is used to store the motion monitoring data of the nuclear magnetic resonance scanning process. The network interface of the motion monitoring device for the nuclear magnetic resonance scanning process is used to communicate with an external terminal through a network connection. The motion monitoring device for the nuclear magnetic resonance scanning process also includes an input and output interface, which is a connection circuit for exchanging information between the processor and the external device, and they are connected to the processor through a bus, referred to as an I / O interface. When the computer program is executed by the processor, a motion monitoring method for a nuclear magnetic resonance scanning process is implemented.

[0131] 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 present application scheme, and does not constitute a limitation on the motion monitoring device for the magnetic resonance imaging process to which the present application scheme is applied. The specific motion monitoring device for the magnetic resonance imaging process may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0132] In one embodiment, a motion monitoring device for a nuclear magnetic resonance scanning process is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps in the above-mentioned various method embodiments when executing the computer program.

[0133] 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 in the above-mentioned method embodiments are implemented.

[0134] In one embodiment, a computer program product is provided, on which a computer program is stored, and the computer program is used by a processor to execute the steps in the above-mentioned various method embodiments.

[0135] Those of ordinary skill 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 above-mentioned 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 memory, storage, database or other media used in the embodiments provided in this 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 or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. 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).

[0136] 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.

[0137] The above 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 invention patent. 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 patent of the present application shall be subject to the attached claims.

Claims

1. A method for motion monitoring during a nuclear magnetic resonance scanning process, characterized in that: The method comprises: In N imaging excitation modules for the imaging layer included in the imaging sequence to be imaged, M insertion positions are set; both N and M are positive integers; At each of the M insertion positions, a motion monitoring and excitation module for a non-imaging layer close to the imaging layer is added to obtain a nuclear magnetic resonance imaging adjustment sequence corresponding to the sequence to be imaged; During the scanning of the scanned object through the magnetic resonance imaging adjustment sequence, the consistency between the latest signal formed based on the motion monitoring excitation module and the historical signal is compared to determine whether the scanned object moves in a direction perpendicular to the imaging layer during the scanning process based on the consistency.

2. The method according to claim 1, characterized in that In the case where the size of the slice selection gradient used by the motion monitoring excitation module is determined before the bandwidth of the radio frequency pulse, the method further includes: Obtaining the position and thickness of the non-imaging layer in a direction perpendicular to the imaging layer; According to the thickness, under the layer selection gradient, determining a layer selection magnetic field range corresponding to the position; Using the frequency range corresponding to the layer selection magnetic field range as the bandwidth of the radio frequency pulse used by the motion monitoring excitation module; Based on the radio frequency pulse corresponding to the bandwidth and the slice selection gradient, a motion monitoring excitation module for the non-imaging layer is obtained.

3. The method according to claim 1, characterized in that In the case where the bandwidth of the radio frequency pulse is determined before the size of the slice selection gradient used by the motion monitoring excitation module, the method further includes: Obtaining the position and thickness of the non-imaging layer in a direction perpendicular to the imaging layer; The size of the layer selection gradient is determined according to the bandwidth, so that under the determined size of the layer selection gradient, the layer selection magnetic field range corresponding to the position corresponds to the thickness.

4. The method according to claim 1, characterized in that: The distance between the non-imaging layer and the imaging layer along a direction perpendicular to the imaging layer is less than or equal to a first set value.

5. The method according to claim 1, characterized in that: When there are multiple imaging layers, and the spacing between adjacent imaging layers along a direction perpendicular to the imaging layers is greater than a second set value, the non-imaging layer is between the adjacent imaging layers.

6. The method according to claim 1, characterized in that The method further comprises: After applying the motion monitoring excitation module, a motion monitoring readout module is applied to obtain a signal formed based on the motion monitoring excitation module.

7. The method according to claim 1, characterized in that The historical signal used to compare the consistency with the latest signal formed by the motion monitoring excitation module is: Based on the signal formed by the target motion monitoring and excitation module; the target motion monitoring and excitation module is a motion monitoring and excitation module applied before the motion monitoring and excitation module that forms the latest signal and is closest to the motion monitoring and excitation module that forms the latest signal in terms of application time.

8. The method according to claim 1, characterized in that Comparing the consistency between the latest signal and the historical signal formed based on the motion monitoring excitation module, including: Obtaining the latest sampling point sequence of the latest signal discretization form; Obtaining a historical sampling point sequence in a discretized form of the historical signal; Based on the difference between the latest sampling point sequence and the historical sampling point sequence, the consistency degree between the latest signal and the historical signal is determined.

9. A motion monitoring device for a nuclear magnetic resonance scanning process, characterized in that: The device comprises: An insertion processing unit, used to set M insertion positions in N imaging excitation modules for the imaging layer included in the sequence to be imaged; both N and M are positive integers; A sequence adjustment unit, configured to add, at each of the M insertion positions, a motion monitoring and excitation module for a non-imaging layer close to the imaging layer, to obtain a nuclear magnetic resonance imaging adjustment sequence corresponding to the sequence to be imaged; The motion monitoring unit is used to compare the consistency between the latest signal formed based on the motion monitoring excitation module and the historical signal during the scanning of the scanned object through the magnetic resonance imaging adjustment sequence, so as to determine whether the scanned object moves in a direction perpendicular to the imaging layer during the scanning process according to the consistency.

10. A motion monitoring device for a nuclear magnetic resonance scanning process, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 8 is implemented.

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