Motion monitoring method, device and equipment during magnetic resonance imaging scanning

Abstract

The present application relates to the field of nuclear magnetic resonance imaging technology, and provides a motion monitoring method, apparatus, and motion monitoring device for a nuclear magnetic resonance scanning process, which can not only monitor the motion of a scanned object in real time during the scanning process, but also reduce the possibility of artifacts in the image. M insertion positions are set in 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 a non-imaging layer adjacent to the imaging layer is added to obtain a nuclear magnetic resonance imaging adjustment sequence; during the scanning of the scanned object using the nuclear magnetic resonance imaging adjustment sequence, the consistency of the latest signal generated based on the motion monitoring excitation module and the historical signal is compared to determine whether the scanned object has moved in a direction perpendicular to the imaging layer during the scanning process.

Description

Technical Field

[0001] The present application relates to the field of nuclear magnetic resonance imaging technology, and in particular to a method and apparatus for monitoring motion during a nuclear magnetic resonance scanning process, a motion monitoring device for 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, wherein 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 size 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 is applied (the frequency gradient is located at G RO The signal is read from the ADC axis (axis), and the signal read corresponds to the ADC axis shown in Figure 1(a); this signal is obtained through the phase gradient of Gy_1. When this 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] According to the above method, 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 method.

[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 scan, it will be time-consuming to find artifacts in the reconstructed image at the end of the scan, and a rescan will be required. Therefore, it is necessary to monitor the patient's motion in real time during the scan.

[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 motion 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, device, motion monitoring equipment, storage medium and computer program product for a nuclear magnetic resonance 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 during 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 generated 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, configured to set M insertion positions in N imaging excitation modules for the imaging layer included in the sequence to be imaged; wherein N and M are both positive integers;

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

[0015] A motion monitoring unit is used to compare the consistency of the latest signal generated by the motion monitoring excitation module with 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 based on 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, and the computer program is used by a processor to execute the above method.

[0018] The present application provides a computer program product having a computer program stored thereon, wherein the computer program is used by a processor to execute the above method.

[0019] In the solution provided in the present application, M insertion positions are set in the N imaging excitation modules for the imaging layer included in the imaging 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, will not interfere with the signal formed based on the imaging excitation module, and will reduce the possibility of artifacts in the reconstructed image; then, through the nuclear magnetic resonance imaging adjustment sequence, during the scanning of the scanned object, the consistency of 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 1 is a flow chart of a method for motion monitoring during a nuclear magnetic resonance scanning process according to 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 according to 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 an MRI scanning 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 coordination of slice selection gradients and radio frequency pulses for slice selection in one embodiment;

[0031] Figure 9 Schematic diagram of consistency comparison based on a discretized sampling point sequence in one embodiment;

[0032] Figure 10 A schematic diagram of introducing a non-imaging layer into a nuclear magnetic resonance scanning process according to one embodiment;

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

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

[0035] Figure 13 FIG. 1 is a diagram showing the internal structure of a motion monitoring device during an MRI scanning process in one embodiment. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0037] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, 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 an imaging layer included in a 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 follows: using radio frequency pulses (RF) and slice gradient direction (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 A specific magnetic field is applied, and after a period of time, the magnetic field in the phase encoding gradient direction is turned off; then, 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 can 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 can be filled into the K space to obtain a phase encoding line, and image reconstruction can 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 in which 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-toe direction of a person (which can be recorded as the z-axis direction). To facilitate the introduction and understanding of the present application, the examples of this application are all based on: the imaging layer is in a transverse plane, and the direction perpendicular to the imaging layer is the head-to-toe direction of a person (which can be recorded as the z-axis direction), as shown in Figures 1(a) and 1(b).

[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 set to include N imaging excitation modules for the imaging layer, that is, these N imaging excitation modules are set 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 an adjusted magnetic resonance imaging 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, where M is a positive integer, and further can be a positive integer greater than or equal to 2.

[0049] For example, 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) need to be used. These six imaging excitation modules are denoted as {101_1, 101_2, 101_3, 101_4, 101_5, 101_6}. By using these six imaging excitation modules, several phase encoding lines required for reconstructing the cross-sectional image of the scanned object in the imaging layer 101 can be obtained.

[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 described in the above example.

[0052] In multilayer imaging, there are multiple imaging layers, such as imaging layer 101, imaging layer 102, and imaging layer 103 shown in Figure 4(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 described in the above example, and the insertion position can be selected 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 the process introduced in another example, for example: the imaging layers 101, 102 and 103 are regarded as the minimum units of the imaging layers, and the three consecutive imaging excitation modules for the minimum units of the imaging layers are regarded as the minimum units of the imaging excitation modules, for example, the imaging excitation modules 101_1, 102_1 and 103_1 are regarded as the minimum units of the imaging excitation modules, and the imaging excitation modules 101_2, 102_2 and 103_2 are regarded as the minimum units of the imaging excitation modules; among the determined imaging excitation module minimum units, at least two insertion positions are selected; in the example shown in Figure 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 an MRI adjustment sequence corresponding to the MRI 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, they are considered to be close.

[0058] After selecting at least two insertion locations, a motion monitoring excitation module targeting the same non-imaging layer is added at each insertion location to obtain an MRI adjustment sequence. The phase encoding gradient corresponding to the motion monitoring excitation module can be omitted, allowing the projection of the object in a specific direction to be directly viewed.

[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 gradient.

[0060] In 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 based on 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 order in which these excitation modules are applied, from earliest to latest, is: imaging excitation module 101_1, motion monitoring excitation module 110_1, imaging excitation module 101_2, motion monitoring excitation module 110_2. During scanning, the corresponding magnetic field is applied in this 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 out the gradient RO. This signal is used for imaging, that is, for reconstructing the cross-sectional image of the scanned object at the imaging layer 101. Then, the motion monitoring excitation module 110_1 is applied. Since no phase encoding gradient is applied, the signal ADC_101_1 is obtained. Figure 5 The exemplary motion monitoring module sets a phase encoding gradient PE. Therefore, after applying the motion monitoring excitation module 110_1, the signal ADC_110_1 is directly obtained by reading out the gradient RO. This 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 sequence.

[0064] Specifically, acquiring the signal formed based on the motion monitoring excitation module may include the steps of: applying the motion monitoring excitation module after applying the motion monitoring readout 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 As can be seen from the sequence shown, ADC_110_1 is the first signal generated by the motion monitoring excitation module obtained in this scan based on the magnetic resonance imaging adjustment sequence. At this time, there is no historical signal and the consistency degree is not determined.

[0066] After applying motion monitoring and excitation module 110_2 and before applying the next motion monitoring module, the latest signal generated by the motion monitoring and excitation module is ADC_110_2, and the historical signal relative to ADC_110_2 is ADC_110_1. The consistency between ADC_110_2 and ADC_110_1 is compared. If the consistency is high, it is determined that the scanned object did not undergo significant motion perpendicular to the imaging layer during the application of imaging excitation modules 101_1 and 101_2. The criterion for determining significant motion is whether the motion causes artifacts in the reconstructed image. If the consistency is low, it is determined that the scanned object did undergo significant motion perpendicular to the imaging layer during the application of imaging excitation modules 101_1 and 101_2. In this case, scanning may be discontinued.

[0067] In the solution provided in the present application, M insertion positions are set in the N imaging excitation modules for the imaging layer included in the imaging 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, will not interfere with the signal formed based on the imaging excitation module, and will reduce the possibility of artifacts in the reconstructed image; then, through the nuclear magnetic resonance imaging adjustment sequence, during the scanning of the scanned object, the consistency of 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] In which, 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 in a 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 according to actual conditions.

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

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

[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 side of the imaging layer in the head direction;

[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-facing 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 toward the foot;

[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 toward the foot;

[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-facing side of the imaging layer, and another imaging layer is on the foot-facing side.

[0077] Figure 7 The relative positions of the non-imaging layer and the imaging layer when there are multiple imaging layers are 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 between 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 in the direction of 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;

[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 closest to the head imaging layer in the head direction, and the other imaging layer is on the side closest to the foot imaging layer in the foot direction;

[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 distance between adjacent imaging layers in the head-to-foot direction is greater than the second set value, the following situations may occur:

[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 that: 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 the 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 that: 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 content about the excitation module, the radio frequency pulse and the slice selection gradient can be used to 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, the Figure 8 The steeper the line corresponding to Gz, the greater the variation in the magnetic field from head to toe along the z-axis. Thus, Gz can be used to impart specific spin frequencies to protons at different z-axis positions in the scanned subject. Applying an RF pulse of a specific frequency can excite protons at a specific location. Applying an RF pulse within a specific frequency range can excite protons within a corresponding range of locations. This frequency range of the RF pulse is referred to as the RF pulse's bandwidth.

[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 the 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 and the layer selection gradient corresponding to the bandwidth, 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 compared to the size of the layer selection gradient used in the motion monitoring excitation module, the method provided in the present application further includes: obtaining the position and thickness of the non-imaging layer in a direction perpendicular to the imaging layer; and 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 the 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, the bandwidth of the radio frequency pulse used by the motion monitoring excitation module is determined in a corresponding manner; 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 generated by the motion monitoring and excitation module can be: a signal generated by applying the motion monitoring and excitation module at any time in the magnetic resonance imaging adjustment sequence;

[0094] Taking the MRI 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 this 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 generated by any applied 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 generated by the motion monitoring and excitation module may also be: a signal generated by the first motion monitoring and excitation module applied in the nuclear magnetic resonance imaging adjustment sequence;

[0097] Taking the MRI 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 MRI adjustment sequence, the first motion monitoring and excitation module is 110_1 . The signal generated by 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 excitation module can also be: a signal formed based on the target motion monitoring excitation module; the target motion monitoring excitation module is a motion monitoring excitation module applied before the motion monitoring excitation module that forms the latest signal and is closest to the motion monitoring excitation module that forms the latest signal in terms of application time.

[0100] Taking the MRI 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 and excitation module is ADC_110_4 generated based on the motion monitoring and excitation module 110_4, then the motion monitoring and excitation module 110_3 that was applied before the motion monitoring and excitation module 110_4 and whose application time was closest to the motion monitoring and excitation module 110_4 is 110_3. Then, a consistency comparison is performed between the signal ADC_110_3 generated based on the motion monitoring and excitation module 110_3 and the latest signal ADC_110_4.

[0102] In one embodiment, comparing the consistency between the latest signal generated by the motion monitoring excitation module and the historical signal includes: obtaining a latest sampling point sequence in a discretized form of the latest signal; obtaining a historical sampling point sequence in a 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 are 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 by subtracting the latest sampling point from the corresponding historical sampling point in sampling order, and the difference sequence can be 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 discretized sampling point sequence of ADC_110_1 and the discretized sampling point sequence of ADC_110_4 are subtracted, such as Figure 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] Furthermore, if the difference sequence is used to represent the difference between the latest sampling point sequence and the historical sampling point sequence, then the degree of consistency between the latest signal and the historical signal is determined based on the difference, including: when one or more difference values ​​in the difference sequence are greater than a set threshold, determining that the degree of consistency between the latest signal and the historical signal is low. For example, if one or three difference values ​​in the difference sequence are greater than the set threshold, it can be considered that the degree of consistency between the latest signal and the historical signal is low.

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

[0110] In one embodiment, when the motion monitoring time resolution is to perform a comparison once for every P signals generated by the motion monitoring excitation module, the degree of consistency between the latest signal generated by the motion monitoring excitation module and the historical signal is compared, including: when the latest signal generated by the motion monitoring excitation module is obtained, determining whether the number of signals between the latest signal and the last compared signal is P; if it is P, then comparing the degree of consistency between the latest signal generated 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 not comparing the degree of consistency between the latest signal generated by the motion monitoring excitation module and the historical signal.

[0111] Reference Figure 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 from 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 of signals ②③④⑤⑥ with signal ① respectively; 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 of signals ③⑤ with signal ① respectively.

[0113] In this embodiment, by adjusting the temporal 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 to, but is not limited to, the Gre_2d sequence, which is a steady-state sequence. Figure 11 (a) is the reconstructed image without motion. There is no artifact in the image. The corresponding curve monitoring is Figure 11 (c), Figure 11The lower curve in (c) is stable, and no movement of the scanned object is detected; Figure 11 (b) is the image reconstructed after the above motion occurs during the scanning process. There are motion artifacts in the image, and the corresponding curve monitoring is Figure 11 (d), Figure 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 various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed 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 portion of steps or stages in other steps.

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

[0117] The insertion processing unit 1201 is configured to set M insertion positions in N imaging excitation modules for imaging layers 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 and excitation module for a non-imaging layer close to the imaging layer at each of the M insertion positions, to obtain a 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 generated by 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 based on the consistency.

[0120] In one embodiment, 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 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; 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; and obtaining 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 in advance compared to the size of the layer selection gradient used by the motion monitoring excitation module, the device further 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; and 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.

[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 in a direction perpendicular to the imaging layers is greater than a second set value, the non-imaging layer is between the adjacent imaging layers.

[0124] In one embodiment, the motion monitoring processing unit is further configured to apply a motion monitoring readout module after applying the motion monitoring excitation module to obtain a signal generated 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 excitation module is: a signal formed based on the target motion monitoring excitation module; the target motion monitoring excitation module is a motion monitoring excitation module applied before the motion monitoring excitation module that forms the latest signal and is closest in application time to the motion monitoring 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 degree of 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 degree of 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 configured to obtain a latest sampling point sequence in a discretized form of the latest signal; obtain a historical sampling point sequence in a discretized form of the historical signal; and determine a degree of consistency between the latest signal and the historical signal based on a 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 multiple differences in the difference sequence are all higher than a set threshold.

[0129] The specific definition of the motion monitoring device for the MRI scanning process can be found in the definition of the motion monitoring method for the MRI scanning process described above, and will not be repeated here. The various modules in the above-mentioned motion monitoring device for the MRI scanning process can be implemented in whole or in part by software, hardware, or a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the motion monitoring device for the MRI scanning process in the form of hardware, or can be stored in the memory of the motion monitoring device for the MRI 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: Figure 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. 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 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. 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 Figure 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 nuclear magnetic resonance scanning process to which the present application scheme is applied. The specific motion monitoring device for the nuclear magnetic resonance scanning process may include more or fewer components than 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. The memory stores a computer program, and the processor implements the steps of the above-mentioned 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. The computer program is used by a processor to execute the steps in the above-mentioned various method embodiments.

[0135] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented 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 may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory may 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 can 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 merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended 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 generated 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 When the size of the slice selection gradient used in the motion monitoring excitation module is determined in advance compared to 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; The frequency range corresponding to the layer selection magnetic field range is used 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 in advance relative to 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, wherein 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, wherein When there are multiple imaging layers, and the distance 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 generated 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 generated by the motion monitoring and excitation module and the historical signal, 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, configured to set M insertion positions in N imaging excitation modules for the imaging layer included in the sequence to be imaged; wherein N and M are both positive integers; a sequence adjustment unit, configured to add a motion monitoring and excitation module for a non-imaging layer close to the imaging layer at each of the M insertion positions, to obtain a magnetic resonance imaging adjustment sequence corresponding to the sequence to be imaged; A motion monitoring unit is used to compare the consistency of the latest signal generated by the motion monitoring excitation module with 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 based on 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.

Images