Magnetic resonance angiography method and magnetic resonance imaging device

Abstract

The invention provides a magnetic resonance imaging method and magnetic resonance imaging equipment, and the method comprises the steps: for each to-be-generated magnetic resonance image in a magnetic resonance image sequence, in a preset time period corresponding to the magnetic resonance image and in an imaging region of at least a target object, carrying out the magnetic resonance imaging on the target object; sequentially generating a layer selection saturation pulse signal and N reversal pulse signals, wherein the N reversal pulse signals are used for performing first reversal operation on tissue in at least the imaging area; after or at the same time as performing the first inversion operation on the tissue in at least the imaging region by using the reciprocal (i + 1) th inversion pulse signal, and before performing the first inversion operation on the tissue in at least the imaging region by using the reciprocal ith inversion pulse signal, performing a second inversion operation on the blood in the marked region; magnetic resonance signals of tissue in the imaging region are acquired and a magnetic resonance image is generated. According to the scheme, the total consumed time of the magnetic resonance imaging process is shorter, and the imaging efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of data processing, and more particularly to a magnetic resonance angiography method, a magnetic resonance imaging device, a non-volatile storage medium, and a computer program product. Background Art

[0002] Magnetic resonance imaging (MRI) is a non-invasive medical imaging technique that uses radiofrequency pulses and gradient magnetic fields to produce detailed images of the human body's internal structures. Unlike X-rays or CT scans, MRI does not use ionizing radiation, making it safer for the subject. 4D MRI technology generates a sequence of multiple MRI images over time. This sequence allows observation of continuous changes in the subject's internal tissue structure.

[0003] To improve the visibility of blood in certain areas of the imaging subject, traditional 4D MRI technology often relies on the use of contrast agents (such as gadolinium-based contrast agents). Although this approach increases the contrast of MRI images, the contrast agent may impose a metabolic burden on the kidneys of the imaging subject. In addition, the use of contrast agents also increases the cost of imaging. In other approaches, MRI images can be generated based on subtraction technology to form an MRI image sequence. Based on subtraction technology, two sets of independent imaging data sets need to be acquired to generate a single MRI image in an MRI image sequence. Therefore, the imaging process is time-consuming and has low imaging efficiency. On the one hand, this seriously affects the imaging subject's experience. On the other hand, it is difficult for the imaging subject to maintain a constant posture during the long imaging process. Changes in posture will result in poor contrast in the MRI images obtained by subtraction. Summary of the Invention

[0004] The present invention is proposed in view of the above problems. The present invention provides a magnetic resonance angiography method, a magnetic resonance imaging device, a non-volatile storage medium and a computer program product.

[0005] According to one aspect of the present invention, a magnetic resonance angiography method is provided, the magnetic resonance angiography method comprising: for each magnetic resonance image to be generated in a magnetic resonance image sequence, in a preset time period corresponding to the magnetic resonance image and in an imaging region of at least a target object, sequentially generating a slice-selective saturation pulse signal and N inversion pulse signals, wherein the N inversion pulse signals are used to perform a first inversion operation on tissue in at least the imaging region, after or simultaneously with performing the first inversion operation on tissue in at least the imaging region using the reciprocal (i+1)th inversion pulse signal of the N inversion pulse signals, and in the reciprocal (i+1)th inversion pulse signal of the N inversion pulse signals. Before performing a first inversion operation on tissue in at least an imaging region using i inversion pulse signals, a second inversion operation is performed on blood in a marked region of the target subject, so that the longitudinal magnetization direction of the blood subjected to the second inversion operation is positive when imaged in the imaging region, where N is a non-negative integer, i is a positive odd number less than or equal to N-1, the marked region is adjacent to the imaging region, and the blood to be imaged flows into the imaging region via the marked region; magnetic resonance signals of the tissue in the imaging region are acquired, and a magnetic resonance image is generated based on the acquired magnetic resonance signals; wherein the later the position of the magnetic resonance image in the magnetic resonance image sequence is, the longer the preset time period corresponding to the magnetic resonance image is.

[0006] Exemplarily, the magnetic resonance angiography method further includes:

[0007] When N is a positive odd number, after the slice-selective saturation pulse signal performs saturation processing on tissue in at least the imaging area and before the first inversion pulse signal among the N inversion pulse signals performs a first inversion operation on tissue in at least the imaging area, another inversion pulse signal is generated in the marking area, wherein the another inversion pulse signal is used to perform a second inversion operation on blood in the marking area.

[0008] Exemplarily, performing a second inversion operation on the blood in the marked area of ​​the target object includes:

[0009] Another inversion pulse signal is generated in the marked area of ​​the target object, wherein the other inversion pulse signal is used to perform a second inversion operation on the blood in the marked area.

[0010] Exemplarily, another inversion pulse signal is generated at the time when generation of the (i+1)th inversion pulse signal from the last is finished, and continues until the time when generation of the (i)th inversion pulse signal from the last is started.

[0011] Exemplarily, performing a second inversion operation on the blood in the marked area of ​​the target object includes:

[0012] A second inversion operation is performed on the blood in the marking area using the (i+1)th inversion pulse signal from the end, wherein the (i+1)th inversion pulse signal from the end is generated in at least the imaging area and the marking area.

[0013] Exemplarily, the length of the marking area along the flow direction of the blood to be imaged is greater than or equal to a first product, and the difference between the length of the marking area and the first product is less than a difference threshold, wherein the first product is the product of the time interval between the penultimate (i+1)th inversion pulse signal and the penultimate (i)th inversion pulse signal and the blood flow velocity of the blood to be imaged.

[0014] Exemplarily, the value of N is determined based on the duration of a preset time period corresponding to the magnetic resonance image.

[0015] Exemplarily, in at least an imaging region of a target object, sequentially generating a slice-selective saturation pulse signal and N inversion pulse signals includes:

[0016] A layer-selected saturation pulse signal and N inversion pulse signals are sequentially generated in a background suppression area of ​​the target object, wherein the background suppression area includes an imaging area, the background suppression area and the imaging area have the same edge adjacent to the marking area, and in the flow direction of the blood to be imaged, the length of the background suppression area is greater than or equal to the maximum value in the second product, the second product includes the product of the time interval between each two adjacent target pulse signals and the blood flow velocity of the blood to be suppressed, and the target pulse signal includes the layer-selected saturation pulse signal and the N inversion pulse signals.

[0017] Exemplarily, acquiring magnetic resonance signals of tissue in an imaging region and generating the magnetic resonance image based on the acquired magnetic resonance signals includes:

[0018] Based on a center-first sampling mode of K-space, magnetic resonance signals of tissues are collected in an imaging region, and data filling of the K-space is performed based on the collected magnetic resonance signals;

[0019] The magnetic resonance image is generated based on the data in the filled K-space.

[0020] Exemplarily, acquiring magnetic resonance signals of tissue in an imaging region and generating the magnetic resonance image based on the acquired magnetic resonance signals further includes:

[0021] For each target encoding gradient, perform the following steps until the data in a row of space corresponding to each target encoding gradient in the filled K space is updated to obtain updated data, where the target encoding gradient is the phase encoding gradient corresponding to the central region in the K space:

[0022] Based on the target encoding gradient, magnetic resonance signals are acquired in the imaging region;

[0023] Update the data in a row of space corresponding to the target encoding gradient;

[0024] Perform inverse Fourier transform on the updated data to obtain a background image;

[0025] The magnetic resonance image is fused with the background image to obtain a fused image.

[0026] Exemplarily, generating the magnetic resonance image based on the acquired magnetic resonance signals includes:

[0027] Filling the K space with data based on the acquired magnetic resonance signals;

[0028] The magnetic resonance image is generated based on the data in the filled K space through a spatiotemporal joint reconstruction algorithm.

[0029] According to another aspect of the present invention, a magnetic resonance imaging device is provided, the magnetic resonance imaging device comprising a processor and an execution device, wherein for each magnetic resonance image to be generated in a magnetic resonance image sequence, the processor is configured to control the execution device to perform the following steps: in a preset time period corresponding to the magnetic resonance image and in an imaging region of at least a target object, sequentially generating a layer-selected saturation pulse signal and N inversion pulse signals, wherein the N inversion pulse signals are used to perform a first inversion operation on tissue in at least the imaging region, after or simultaneously with performing the first inversion operation on tissue in at least the imaging region using the reciprocal (i+1)th inversion pulse signal among the N inversion pulse signals, and Before the i-th inversion pulse signal from the inversion pulse signal performs a first inversion operation on tissue in at least an imaging area, a second inversion operation is performed on blood in a marking area of ​​the target object, so that the longitudinal magnetization direction of the blood after the second inversion operation is positive when imaged in the imaging area, N is a non-negative integer, i is a positive odd number less than N, the marking area is adjacent to the imaging area, and the blood to be imaged flows into the imaging area through the marking area; magnetic resonance signals of tissue in the imaging area are acquired; the processor is further configured to generate the magnetic resonance image based on the acquired magnetic resonance signals; wherein, the later the position of the magnetic resonance image in the magnetic resonance image sequence is, the longer the preset time period corresponding to the magnetic resonance image is.

[0030] According to another aspect of the present invention, a non-volatile storage medium is provided, wherein program instructions are stored on the non-volatile storage medium, and the program instructions are used to execute the above-mentioned magnetic resonance angiography method when running.

[0031] According to another aspect of the present invention, a computer program product is further provided, wherein the computer program product comprises computer program instructions, and when the computer program instructions are executed by a processor, the computer program instructions are used to execute the above-mentioned magnetic resonance angiography method.

[0032] According to the above-mentioned solution of the present invention, on the one hand, the use of contrast agents is not required, which is more friendly to the health of the target subject and lowers the cost. In addition, since subtraction technology is not required, the total time required for the magnetic resonance imaging process in the above-mentioned solution is shortened, significantly improving imaging efficiency and also helping to reduce the impact of changes in the target subject's posture on the imaging contrast of the magnetic resonance image. On the other hand, the duration of the preset time period corresponding to each magnetic resonance image varies, and compared with solutions using preset time periods of fixed lengths, the imaging efficiency provided by the solution provided by the present invention is also higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and other objects, features, and advantages of the present invention will become more apparent through a more detailed description of the embodiments of the present invention with reference to the accompanying drawings. The accompanying drawings are provided to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and are not intended to limit the present invention. In the drawings, the same reference numerals generally represent the same components or steps.

[0034] Figure 1 FIG2 shows a schematic flow chart of a magnetic resonance angiography method according to an embodiment of the present invention;

[0035] Figure 2 A schematic diagram showing a magnetic resonance angiography method according to an embodiment of the present invention is shown;

[0036] Figure 3 A schematic diagram showing a magnetic resonance angiography method according to an embodiment of the present invention is shown;

[0037] Figure 4 A schematic diagram showing a marking area, an imaging area, and a background suppression area according to an embodiment of the present invention is shown;

[0038] Figure 5 Schematic diagram showing magnetic resonance images a2 to e2 in a magnetic resonance image sequence according to one embodiment of the present invention;

[0039] Figure 6 A schematic diagram showing a process of generating a magnetic resonance image f according to an embodiment of the present invention;

[0040] Figure 7 A schematic block diagram of a magnetic resonance imaging device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention more apparent, exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein. Based on the embodiments of the present invention described in the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0042] In order to at least partially solve the above problems, an embodiment of the present invention provides a magnetic resonance angiography method. Figure 1 FIG. 1 shows a schematic flow chart of a magnetic resonance angiography method according to an embodiment of the present invention. Figure 1 As shown, the method may include the following steps S110 and S120.

[0043] In step S110 , for each magnetic resonance image to be generated in the magnetic resonance image sequence, a slice-selective saturation pulse signal and N inversion pulse signals are sequentially generated in a preset time period corresponding to the magnetic resonance image and in at least an imaging region of the target object.

[0044] The MRI sequence may include multiple MRI images to be generated. Once each MRI image has been generated, the user can determine the actual blood flow of the target subject by viewing the MRI sequence. It will be appreciated that the MRI sequence may be a video comprising multiple MRI images.

[0045] For example, magnetic resonance imaging equipment can be used to acquire magnetic resonance signals from a target subject. The target subject can be a human subject undergoing magnetic resonance imaging. The magnetic resonance imaging equipment can include a scanner, an examination platform, and a host computer. The scanner has a space for accommodating the examination platform. The target subject can lie flat on the examination platform, which can then be moved into the space. Hydrogen atoms in the target subject's tissue are affected by the magnetic force of the main magnetic field (also known as the B0 magnetic field). From a macroscopic perspective, this can be seen as a net magnetization vector formed by several hydrogen atoms with a direction close to the Z-axis. The Z-axis direction can be the direction from the head placement area to the foot placement area on the examination platform. The head placement area can be used to place the target subject's head, and the foot placement area can be used to place the target subject's feet. When a radio frequency pulse signal (such as the slice-selective saturation pulse signal and inversion pulse signal in the embodiments of the present application) is applied to at least the imaging area of ​​the target subject, some hydrogen atoms in the application area absorb energy, transitioning from a low-energy state to a high-energy state. From a macroscopic perspective, this can be seen as a change in the direction of the net magnetization vector. After the RF pulse signal is applied, the high-energy hydrogen atoms relax, generating an electrical signal that is received by the scanner. The scanner converts the electrical signal into a digital signal and sends it to the host computer, which uses the MRI algorithm to generate an MRI image.

[0046] The imaging area of ​​the target object may be a portion of the target object's body that the user desires to observe. For example, if the user desires to observe the target object's head, the imaging area may be the target object's head area, or a portion of the head area. For another example, if the user desires to observe the target object's kidneys, the imaging area may be the target object's kidney area, or a portion of the kidney area. It is understood that the user may also select the imaging area of ​​the target object based on actual needs, and this embodiment of the present invention does not impose any limitation thereto.

[0047] The preset time period corresponding to each magnetic resonance image to be generated may be different. For each magnetic resonance image to be generated, the later the magnetic resonance image is in the magnetic resonance image sequence, the longer the preset time period corresponding to the magnetic resonance image is.

[0048] For each magnetic resonance image to be generated, the preset time period corresponding to the magnetic resonance image may include a period from a first moment to a second moment. The first moment is the start time of generating the slice-selective saturation pulse signal used to generate the magnetic resonance image. The second moment is the start time of signal acquisition for the magnetic resonance image. In practical scenarios, for example, a magnetic resonance image a1 in a magnetic resonance image sequence corresponds to a preset time period of 1000 milliseconds. Magnetic resonance image a1 can be used to display blood that has newly flowed into the imaging region within 1000 milliseconds. For example, the last magnetic resonance image e1 in the magnetic resonance image sequence corresponds to a preset time period of 2000 milliseconds. Magnetic resonance image e1 can be used to display blood that has newly flowed into the imaging region within 2000 milliseconds. Since the later a magnetic resonance image is in the magnetic resonance image sequence, the longer the preset time period corresponding to that image, magnetic resonance image e1 can be located after magnetic resonance image a1. It is understood that the two images may not be adjacent, that is, there may be at least one magnetic resonance image between them. When viewing this magnetic resonance image sequence, a user can observe the continuous infusion of blood into the blood vessels in the imaging region. It will be appreciated that the specific duration of each preset time period corresponding to each magnetic resonance image to be generated can be set by the developer or user based on actual needs. For example, the smaller the difference in the duration of the preset time periods between adjacent magnetic resonance images, the more magnetic resonance images can be included in the magnetic resonance sequence, and the smoother the visual effect of blood flowing into the blood vessels in the imaging area.

[0049] The slice-selective saturation pulse signal can be used to adjust the direction of the net magnetization vector to be close to the X-axis. The X-axis can be the direction from the left hand placement area to the right hand placement area on the examination platform. The left hand placement area can be used to place the subject's left hand, and the right hand placement area can be used to place the subject's right hand. Through this process, the components of the net magnetization vector in the planes containing the X and Y axes increase. As hydrogen atoms precess, a time-varying magnetic resonance signal is generated. The Y-axis can be the vertical axis. For example, if the signal intensity of the magnetic resonance signal (hereinafter referred to as the signal) corresponding to untreated blood is considered 1 (a value greater than 0 is considered to indicate a positive longitudinal magnetization direction, which can be considered the direction of the net magnetization vector's projection on the Z-axis), and the signal intensity after applying the inversion pulse signal to the blood is considered -1 (a value less than 0 is considered to indicate a negative longitudinal magnetization direction), then ideally, the slice-selective saturation pulse signal can adjust the signal intensity of the signal generated by the tissue in the application area to 0. It is understood that the tissue in the application area may include solid tissue, such as fat and brain tissue, as well as fluid tissue, such as blood and cerebrospinal fluid. Thus, background signal suppression can be achieved through the slice-selective saturation pulse signal. It is understood that the slice-selective saturation pulse signal may include a single pulse or multiple pulses.

[0050] In one example, the layer-selective saturation pulse signal can be generated only in the imaging area. In another example, the layer-selective saturation pulse signal can also be generated in an area larger than the imaging area. The larger area at least includes the imaging area. Applying the layer-selective saturation pulse signal to a larger area can more effectively suppress the signal of solid tissue to near zero, thereby reducing its impact on the imaging quality. This can also suppress the background signal of venous blood, which flows in the opposite direction to the direction of arterial blood. In addition, it can also ensure that even if the tissue is located at the edge of the imaging area, its signal can be fully suppressed, thereby avoiding signal contamination caused by edge effects. Developers can determine the application area of ​​the layer-selective saturation pulse signal according to actual needs, and the embodiments of the present invention do not limit this. For the convenience of description, the application area of ​​the layer-selective saturation pulse signal is referred to as the background suppression area of ​​the target object.

[0051] N inversion pulse signals may be used to perform a first inversion operation on tissue in at least the imaging region. N may be a non-negative integer. In one example, N may also be 0. Specifically, after the slice-selective saturation pulse signal saturates tissue in at least the imaging region, acquisition of signals for generating a magnetic resonance image may begin without generating any inversion pulse signals. This magnetic resonance image may be an earlier magnetic resonance image in a magnetic resonance image sequence.

[0052] Similar to the slice-selective saturation pulse signal, the inversion pulse signal can be generated only in the imaging area. Alternatively, the inversion pulse signal can be generated in a larger area than the imaging area. This larger area includes the imaging area. It will be appreciated that the application area of ​​the inversion pulse signal can be the same as or different from the application area of ​​the slice-selective saturation pulse signal. For ease of description, the following embodiments illustrate the case where both application areas are the same background suppression area.

[0053] From a macroscopic perspective, the above-mentioned inversion pulse signal can be used to implement a first inversion operation. The first inversion operation can be used to reverse the direction of the net magnetization vector of the tissue in the application area of ​​the inversion pulse signal. For example, through the above-mentioned first inversion operation, the direction of the above-mentioned net magnetization vector can be reversed 180 degrees. After an appropriate inversion recovery time (Inversion Time, or TI), the intensity of the net magnetization vector can be close to zero. Therefore, the above-mentioned inversion pulse signal can also be used to selectively suppress background signals. It can be understood that the above-mentioned inversion pulse signal may include a single pulse or multiple pulses. The target parameters of multiple inversion pulse signals (for example, pulse frequency, pulse duration, pulse intensity, etc.) may be the same.

[0054] In one example, N may be 4. Figure 2 , Figure 2FIG2 is a schematic diagram showing a magnetic resonance angiography method according to an embodiment of the present invention. Figure 2 , the inversion pulse signals are arranged in reverse chronological order, and the N inversion pulse signals may include inversion pulse signals 1 to 4. For example, with the time point of magnetic resonance signal acquisition being time 0, the generation start time of the slice-selective saturation pulse signal may be -2000 milliseconds, the generation start time of inversion pulse signal 4 may be approximately -1652.1 milliseconds, the generation start time of inversion pulse signal 3 may be approximately -987.7 milliseconds, the generation start time of inversion pulse signal 2 may be approximately -435.8 milliseconds, and the generation start time of inversion pulse signal 1 may be approximately -107 milliseconds. The period from the generation start time of the slice-selective saturation pulse signal to time 0 may be the preset period corresponding to the magnetic resonance image in this example.

[0055] Regardless of whether N is any integer greater than 1, after or simultaneously with performing a first inversion operation on at least the tissue in the imaging region using the (i+1)th inversion pulse signal from the N inversion pulse signals, and before performing the first inversion operation on at least the tissue in the imaging region using the (i)th inversion pulse signal from the N inversion pulse signals, a second inversion operation may be performed on the blood in the marked region of the target subject. This second inversion operation can cause the longitudinal magnetization direction of the blood subjected to this inversion operation to be uniformly positive when imaged in the imaging region. i is a positive odd number less than or equal to N-1.

[0056] For the case where N is 1, after the slice-selective saturation pulse signal saturates the tissue in at least the imaging region and before the inversion pulse signal performs a first inversion operation on the tissue in at least the imaging region, an additional inversion pulse signal (the additional inversion pulse signal relative to the N inversion pulse signals, hereinafter referred to as the first pulse signal) may be generated in the marking region. It will be understood that for the case where N is 1, N-1=0, and there is no positive odd number less than or equal to N-1. That is, for the case where N is 1, the i+1th inversion pulse signal mentioned above does not exist. See [Referring to the following text] Figure 3 , Figure 3 FIG. 1 is a schematic diagram showing a magnetic resonance angiography method according to an embodiment of the present invention. Figure 3In the example, N is 1. A first pulse signal h can be generated in the marking region after the slice-selective saturation pulse signal saturates tissue in at least the imaging region and before the inversion pulse signal 1 performs a first inversion operation on tissue in at least the imaging region. No other inversion pulse signals may be generated between the start of inversion pulse signal 1 generation and the start of signal acquisition (see the imaging start time in the figure). Specifically, in this example, the longitudinal magnetization direction of blood flowing into the imaging region between the end of the slice-selective saturation pulse signal generation and the start of inversion pulse signal 1 is initially positive. This blood first undergoes the second inversion operation of the first pulse signal h in the marking region. It then undergoes the first inversion operation of the inversion pulse signal 1 in the imaging region. Therefore, the longitudinal magnetization direction of the blood when imaged in the imaging region is positive.

[0057] The marking area is adjacent to the imaging area and the blood to be imaged flows into the imaging area via the marking area. It is understood that the blood to be imaged can be arterial blood or venous blood.

[0058] See Figure 4 , Figure 4 Schematic diagram showing a marking area, an imaging area, and a background suppression area according to an embodiment of the present invention. Figure 4 For example, the imaging area is a portion of the target subject's brain region. In this example, the blood to be imaged is cerebral arterial blood. Since the heart, which supplies cerebral arterial blood, is located below the brain region, the area below the brain region can be used as the aforementioned marked area. Figure 4 The figure also shows an example where the imaging area is the kidney area of ​​the target object. In this example, the arterial blood to be imaged flows from the heart through the abdominal aorta into the kidney area. The heart is located above the kidney area. Therefore, in this example, the area above the kidney area can be used as the above-mentioned marked area. Similarly, Figure 4 The figure also shows an example where the imaging area is the target subject's hip region. In this example, the area above the hip region can be used as the aforementioned marked area. The specific locations of the aforementioned marked and imaging areas can be determined by the developer or user and are not limited in this embodiment of the present invention. It is understood that the blood to be imaged can be either arterial or venous blood.

[0059] Continue reading Figure 2In the example where N is equal to 4, i can be 1 or 3. For example, after the inversion pulse signal 2 (the i+1th to last inversion pulse signal in this example, i is 1 here as an example) performs a first inversion operation on at least the tissue in the imaging area (in other examples, it can be simultaneous with it), and before the first to last inversion pulse signal (the i-th to last inversion pulse signal in this example) performs the first inversion operation on at least the tissue in the imaging area, a second inversion operation can be performed on the blood in the marked area of ​​the target object (in this example, the first pulse signal a is used to perform the above-mentioned second inversion operation). For another example, after the inversion pulse signal 4 (the i+1th to last inversion pulse signal in this example, i is 3 here as an example) performs a first inversion operation on at least the tissue in the imaging area (in other examples, it can be simultaneous with it), and before the third to last inversion pulse signal (the i-th to last inversion pulse signal in this example) performs the first inversion operation on at least the tissue in the imaging area, a second inversion operation can be performed on the blood in the marked area of ​​the target object (in this example, the first pulse signal b is used to perform the above-mentioned second inversion operation).

[0060] Because the marking region is adjacent to the imaging region, and the blood to be imaged flows into the imaging region through the marking region, a pre-inversion operation (i.e., a second inversion operation) is performed in the marking region on the blood that will flow into the imaging region within a preset time period before imaging. Thus, due to the combined effects of the first and second inversion operations, the longitudinal magnetization direction of the blood that has flowed into the imaging region within the preset time period is positive during imaging. In step S120, for each magnetic resonance image to be generated in the magnetic resonance image sequence, magnetic resonance signals of tissue in the imaging region are acquired, and the magnetic resonance image is generated based on the acquired magnetic resonance signals.

[0061] For each magnetic resonance image to be generated in a magnetic resonance image sequence, magnetic resonance signals of tissue in the imaging region may be acquired after the cycle corresponding to the magnetic resonance image has completed. In some examples, multiple preset phase encoding gradients may be sequentially applied in at least the imaging region using gradient coils in a scanner to sequentially form multiple gradient magnetic fields. Each phase encoding gradient may correspond to a row in K-space. Magnetic resonance signals acquired in the gradient magnetic field formed based on the phase gradient encoding may be filled into the row in K-space corresponding to the phase gradient encoding. The data in the filled K-space may be converted into a magnetic resonance image using an inverse Fourier transform. In one example, magnetic resonance signals corresponding to only a portion of K-space may be acquired, and then, based on the conjugate symmetry of K-space, a preset algorithm may be used to complete the unfilled space in K-space. A magnetic resonance image is then generated using the data in the fully filled K-space. It will be appreciated that if 3D imaging technology is used, the data in K-space may be acquired sequentially in blocks, but this is not a limitation in the present embodiment.

[0062] In some embodiments, various magnetic resonance imaging techniques may be used to generate magnetic resonance images, such as MP-RAGE (Magnetization Prepared Rapid Gradient Echo) imaging, GRE (Gradient Recalled Echo) imaging, FSE (Fast Spin Echo) imaging, balanced Steady State Free Processing (bSSFP), and stack-of-star golden angle imaging.

[0063] In one example, the magnetic resonance image can be processed using an image processing algorithm before being displayed. For example, the magnetic resonance image can be subjected to feature enhancement or noise suppression. In another example, a region segmentation algorithm or model can be used to determine a region of interest in the magnetic resonance image.

[0064] See Figure 5 , Figure 5 Schematic diagram showing magnetic resonance images a2 to e2 in a magnetic resonance image sequence according to an embodiment of the present invention. Figure 5 The solid rectangle in the image may represent the background suppression area mentioned above. The dashed rectangle may represent the imaging area mentioned above. The mosaic area may represent the marked area mentioned above. In magnetic resonance images a2 through e2, the area occupied by blood flowing into the imaging area during the preset time period increases as the preset time period increases. As magnetic resonance images are continuously generated, the user can view the blood flow process of the blood vessels in the imaging area through the magnetic resonance image sequence.

[0065] According to the above-mentioned solution of the embodiment of the present invention, on the one hand, it does not require the use of contrast agents, which is more friendly to the health of the target subject and lowers the cost. In addition, it does not require the use of subtraction technology, so the total time required for the magnetic resonance imaging process in the above-mentioned solution is shortened, significantly improving imaging efficiency and also helping to reduce the impact of changes in the target subject's posture on the imaging contrast of the magnetic resonance image. On the other hand, the duration of the preset time period corresponding to each magnetic resonance image varies, and compared with solutions using preset time periods of fixed lengths, the imaging efficiency of the solution provided by the present invention is also higher.

[0066] Exemplarily, the above-mentioned magnetic resonance angiography method further includes: when N is a positive odd number, after the slice-selective saturation pulse signal performs saturation processing on tissue in at least the imaging area, and before the first inversion pulse signal among the N inversion pulse signals performs a first inversion operation on tissue in at least the imaging area, generating another inversion pulse signal (hereinafter referred to as the first pulse signal) in the marking area.

[0067] The first pulse signal is used to perform a second inversion operation on the blood in the marking area. Specifically, the longitudinal magnetization direction of the blood after the second inversion operation can be positive when imaged in the imaging area. Figure 6 As shown, Figure 6 FIG. 1 is a schematic diagram showing a process of generating a magnetic resonance image f according to an embodiment of the present invention. Figure 6 In the example where N is 3, after the slice-selective saturation pulse signal saturates at least the tissue in the imaging region and before the inversion pulse signal 3 (the first inversion pulse signal in this example) performs a first inversion operation on at least the tissue in the imaging region, a first pulse signal f can be generated in the marking region. Specifically, blood flowing into the imaging region between the end of the slice-selective saturation pulse signal generation and the start of the inversion pulse signal 3 has an initial positive longitudinal magnetization direction. This blood first undergoes the second inversion operation of the first pulse signal f in the marking region and then sequentially undergoes the first inversion operations of the inversion pulse signals 3 to 1 in the imaging region. Therefore, the longitudinal magnetization direction of the blood when imaged in the imaging region is positive. For another example, blood flowing into the imaging region between the end of the inversion pulse signal 3 and the start of the inversion pulse signal 2 has an initial positive longitudinal magnetization direction. This blood sequentially undergoes the first inversion operations of the inversion pulse signals 2 and 1 in the imaging region. Therefore, the longitudinal magnetization direction of the blood when imaged in the imaging region is positive. For another example, blood that flows into the imaging region between the end of inversion pulse signal 2 and the start of inversion pulse signal 1 has an initially positive longitudinal magnetization direction. This blood first undergoes the second inversion operation of the first pulse signal e in the marking region and then undergoes the first inversion operation of the inversion pulse signal 1 in the imaging region. Therefore, the longitudinal magnetization direction of this blood when imaged in the imaging region is positive.

[0068] According to the above-described solution of an embodiment of the present invention, when N is a positive odd number, a first pulse signal can be generated in the marking region after the slice-selective saturation pulse signal saturates tissue in at least the imaging region and before the first of the N inversion pulse signals performs a first inversion operation on tissue in at least the imaging region. This solution utilizes the first pulse signal to perform a second inversion operation on blood flowing through the marking region after the slice-selective saturation pulse signal is generated and before the first inversion pulse signal is generated. This ensures that the longitudinal magnetization direction of the blood undergoing this second inversion operation is uniformly positive when imaged in the imaging region. This solution can improve the display quality of magnetic resonance images, and thereby improve the display quality of magnetic resonance image sequences.

[0069] Exemplarily, for each magnetic resonance image to be generated in the magnetic resonance image sequence, the value of N may be determined based on the duration of a preset time period corresponding to the magnetic resonance image.

[0070] In one example, for each magnetic resonance image to be generated, the value of N can be determined based on the pulse duration of the inversion pulse signal and the duration of the preset time period. Specifically, the duration of the preset time period corresponding to the magnetic resonance image can be greater than or equal to a target duration. The target duration can be the sum of the pulse durations of the slice-selective saturation pulse signal and the N inversion pulse signals. For example, for an MRI image positioned relatively early in the MRI image sequence, MRI image signal acquisition can begin immediately after the slice-selective saturation pulse signal saturates at least the tissue in the imaging region. For another example, for an MRI image positioned relatively late in the MRI image sequence, MRI image signal acquisition can begin after the slice-selective saturation pulse signal saturates at least the tissue in the imaging region and the N inversion pulse signals perform a first inversion operation on the tissue. The longer the duration of the preset time period corresponding to these MRI images, the larger the value of N can be; otherwise, the value of N is reversed. For any pair of adjacent MRI images in the MRI image sequence, the value of N corresponding to the earlier MRI image can be less than or equal to the value of N corresponding to the later MRI image.

[0071] According to the above-described solution of an embodiment of the present invention, for each magnetic resonance image to be generated in a magnetic resonance image sequence, the value of N can be determined based on the duration of the preset time period corresponding to the magnetic resonance image. This solution provides a more flexible value for N, thereby improving the adaptability of the magnetic resonance angiography method. This also facilitates improved display quality of magnetic resonance images and magnetic resonance image sequences.

[0072] Exemplarily, in step S110, sequentially generating a layer-selected saturation pulse signal and N inversion pulse signals in at least the imaging area of ​​the target object may include: sequentially generating a layer-selected saturation pulse signal and N inversion pulse signals in the background suppression area of ​​the target object.

[0073] The background suppression region may include the imaging region. The background suppression region and the imaging region have the same edges that are adjacent to the marking region. Figure 4 For an example in which the imaging region is the brain region, the lower edges of the background suppression region and the imaging region are the same edge, and this edge is adjacent to the marked region. For an example in which the imaging regions are the kidney region and the hip region, respectively, the upper edges of the background suppression region and the imaging region are the same edge, and this edge is adjacent to the marked region.

[0074] For ease of understanding, the embodiment of the present invention collectively refers to the layer-selected saturation pulse signal and the N inversion pulse signals as target pulse signals. The second product includes the product of the time interval between each two adjacent target pulse signals and the blood flow velocity of the blood to be suppressed. For example, continue to refer to Figure 2 For example, the second product may include: the product of the time interval between the layer-selected saturation pulse signal and the inversion pulse signal 4 and the blood flow velocity of the blood to be suppressed, the product of the time interval between the inversion pulse signal 4 and the inversion pulse signal 3 and the blood flow velocity of the blood to be suppressed, etc. In the flow direction of the blood to be imaged, the length of the background suppression area is greater than or equal to the maximum value in the second product. In this way, it is ensured that all signals of the blood to be suppressed that flows into the imaging area can be fully and effectively suppressed, reducing their interference with the signal of the blood to be imaged. The blood to be suppressed may be blood that the user is not concerned about. For example, in the case where the user is concerned about the flow state of the arterial blood in the brain, the above-mentioned blood to be suppressed may include the venous blood in the brain.

[0075] According to the above-described scheme of an embodiment of the present invention, a layer-selected saturation pulse signal and N inversion pulse signals can be sequentially generated within the background suppression region of the target object. The background suppression region may include the imaging region and other regions. Because the saturation pulse signal and the N inversion pulse signals have a larger range of action than the imaging region, background signal interference is reduced, the signal-to-noise ratio is improved, and the imaging contrast of the blood being imaged can be enhanced. This facilitates improved display quality of magnetic resonance images, and thus, improved display quality of magnetic resonance image sequences. Furthermore, a background suppression region of the aforementioned size avoids artifacts in magnetic resonance images, and prevents excessive scanning times and unnecessary increases in computing resource consumption.

[0076] Illustratively, the above-mentioned second reversal operation on the blood in the marked area of ​​the target object may include: generating another reversal pulse signal (hereinafter referred to as the first pulse signal) in the marked area of ​​the target object. The first pulse signal can be used to perform a second reversal operation on the blood in the marked area. The above-mentioned second reversal operation can be used to reverse the direction of the net magnetization vector formed by the tissue in the marked area. For example, the above-mentioned second reversal operation can reverse the direction of the above-mentioned net magnetization vector by 180 degrees. In one example, the target parameter of the above-mentioned first pulse signal may be the same as the target parameter of the reversal pulse signal in step S110 to implement the first reversal operation. In another example, a pulse signal with a different pulse type that can reverse the direction of the net magnetization vector may also be used. The above-mentioned first pulse signal may include a single pulse or multiple pulses, and the embodiment of the present invention is not limited here.

[0077] In the above Figure 2 In a related example, a first pulse signal for performing a second inversion operation may be generated between the time when inversion pulse signal 1 is generated (i.e., -107 milliseconds) and the time when inversion pulse signal 2 is generated (i.e., -435.8 milliseconds). A first pulse signal for performing a second inversion operation may also be generated between the time when inversion pulse signal 3 is generated (i.e., -987.7 milliseconds) and the time when inversion pulse signal 4 is generated (i.e., -1652.1 milliseconds). Arterial blood flowing into the imaging region during the period between time 0 and time -107 milliseconds does not experience any inversion pulse signals. Arterial blood flowing into the imaging region during the period between time -435.8 milliseconds and time -987.7 milliseconds and before time -1652.1 milliseconds has already experienced an even number of inversion pulse signals applied in the background suppression region by time 0. For the arterial blood flowing into the imaging area between time -107 milliseconds and time -435.8 milliseconds, by time 0, it not only experienced the inversion pulse signal 1 applied to the background suppression area, but also experienced the first pulse signal applied to the marking area before flowing into the background suppression area. In other words, the arterial blood in the imaging area between time -107 milliseconds and time -435.8 milliseconds underwent a pre-inversion operation (i.e., a second inversion operation) in the marking area through which it flowed. Similarly, the arterial blood flowing into the imaging area between time -1652.1 milliseconds and time -987.7 milliseconds experienced the first pulse signal, inversion pulse signal 3, inversion pulse signal 2, and inversion pulse signal 1 in the marking area by time 0. Thus, by time 0, all arterial blood in the imaging area had experienced an even number of inversion pulse signals. This ensures that the blood that successively flows into the imaging area has a positive signal at time 0, maintaining sufficient signal strength.

[0078] According to the above-described solution of an embodiment of the present invention, a first pulse signal can be generated in the marked region of the target object. This first pulse signal can more effectively perform a second inversion operation on the blood in the marked region, thereby improving the display quality of the magnetic resonance image. This also helps improve the display quality of the magnetic resonance image sequence.

[0079] Exemplarily, another inversion pulse signal (hereinafter referred to as the first pulse signal) is generated at the end time of the generation of the (i+1)th inversion pulse signal from the end, and continues until the start time of the generation of the (i)th inversion pulse signal from the end.

[0080] In this example, the pulse duration of the first pulse signal may be greater than the pulse duration of any inversion pulse signal among the N inversion pulse signals. The pulse durations of any inversion pulse signal among the multiple first pulse signals may also be different.

[0081] Combine Figure 2 In the example where N is 4, the first pulse signal may be generated at the end of the generation of the inversion pulse signal 2 and continue until the start of the generation of the inversion pulse signal 1. The first pulse signal may also be generated at the end of the generation of the inversion pulse signal 4 and continue until the start of the generation of the inversion pulse signal 3.

[0082] In one example, when N is a positive odd number, a first pulse signal may be generated at the end of the generation of the layer selection saturation pulse signal, and the first pulse signal may last until the start of the generation of the first inversion pulse signal. Figure 6 In the example where N is 3, the first pulse signal f can be generated at the end time of the generation of the layer-selected saturation pulse signal, and it continues until the start time of the generation of the inversion pulse signal 3 (the first inversion pulse signal in this example).

[0083] According to the above-described solution of an embodiment of the present invention, the first pulse signal is generated at the end of the generation of the (i+1)th inversion pulse signal from the last digit and continues until the start of the generation of the (i)th inversion pulse signal from the last digit. This solution can enhance the pre-inversion effect of the blood to be imaged by using the first pulse signal with a longer duration, thereby facilitating enhanced imaging contrast of the blood to be imaged. This facilitates improved display quality of magnetic resonance images, and thereby enhanced display quality of magnetic resonance image sequences.

[0084] Illustratively, performing the second inversion operation on the blood in the marked area of ​​the target object may include: performing the second inversion operation on the blood in the marked area using the (i+1)th inversion pulse signal from the last digit.

[0085] As previously described, the N inversion pulse signals can perform a first inversion operation on the blood in the background suppression area. The effective range of the (i+1)th inversion pulse signal from the N inversion pulse signals can be expanded. For example, the (i+1)th inversion pulse signal from the last can be generated in at least the imaging area and the marking area. Specifically, for example, the effective range of the inversion pulse signal can include the marking area and the aforementioned background suppression area. In this example, the (i+1)th inversion pulse signal from the last can be used not only to perform the first inversion operation on the tissue in the background suppression area, but can also be used to perform a second inversion operation on the blood in the marking area.

[0086] Continue reading Figure 2 , the second inversion operation can be performed on the blood in the marked area using the inversion pulse signal 4 and the inversion pulse signal 2 (the penultimate i+1 inversion pulse signal in this example, where i can be 3 or 1). In this example, the first pulse signal is not required. Figure 6 , a second inversion operation can be performed on the blood in the marked area using inversion pulse signal 2 (the penultimate (i+1) inversion pulse signal in this example, where i can be 1). In this example, in addition to using the first pulse signal f to perform the second inversion operation, no other inversion pulse signal is required to perform the second inversion operation.

[0087] According to the above scheme of the embodiment of the present invention, the penultimate (i+1) inversion pulse signal can be used to perform the second inversion operation, thereby reducing the total amount of inversion pulse signals generated, which is beneficial to reducing the configuration cost of the host computer and the scanner, and improving the adaptability of magnetic resonance angiography to different scenarios.

[0088] Exemplarily, the length of the marking area along the flow direction of the blood to be imaged is greater than or equal to the first product, and the difference between the length of the marking area and the first product is less than a difference threshold.

[0089] The first product can be the product of the time interval between the (i+1)th and (i)th inversion pulse signals before and after the (i)th inversion pulse signal before and after, and the blood flow velocity of the blood to be imaged. The specific value of the difference threshold can be determined by the developer based on actual needs. By setting the difference threshold, a reasonable size of the marked area can be ensured.

[0090] The background suppression area can be extended by the length of the first product toward the side of the source of the blood to be imaged to expand the range of action of the penultimate (i+1) inversion pulse signal. For example, if the blood flow velocity of the blood flow to be imaged is 0.03 cm per millisecond and the above time interval is 300 milliseconds, the first product can be 9 cm (i.e., 0.03*300). The background suppression area of ​​the inversion pulse signal can be extended by 9 cm to utilize the penultimate (i+1) inversion pulse signal to pre-reverse the longitudinal magnetization direction of the blood that is about to flow into the imaging area. It can be understood that the time interval between the penultimate (i+1) inversion pulse signal and the penultimate (i) inversion pulse signal can change with the change of i. In other words, the above length of the marking area can be different for different inversion pulse signals. The above scheme can flexibly configure the range of action of the inversion pulse signal based on the first product.

[0091] According to the above-described solution of the embodiment of the present invention, on the one hand, the penultimate (i+1) inversion pulse signal can be used for the second inversion operation, thereby reducing the total number of inversion pulse signals generated, which helps reduce the configuration cost of magnetic resonance imaging equipment and improves the adaptability of magnetic resonance angiography for different scenarios. On the other hand, the effective range of the inversion pulse signal can be flexibly configured based on the blood flow velocity of the blood to be imaged. This not only fully inverts the blood to be imaged, but also effectively improves the imaging contrast of the blood to be imaged.

[0092] Exemplarily, acquiring magnetic resonance signals of tissues in the imaging region and generating the magnetic resonance image based on the acquired magnetic resonance signals in step S120 may include: step S121a and step S122a.

[0093] In step S121a, magnetic resonance signals of tissues are acquired in the imaging region based on a center-first sampling mode of the K-space, and data filling is performed on the K-space based on the acquired magnetic resonance signals.

[0094] K space can be used to store data of magnetic resonance images in the frequency domain. In magnetic resonance imaging, the collected data can be filled into the K space, and then the data in the frequency domain can be converted into data in the spatial domain (or image domain) to obtain a magnetic resonance image. The above-mentioned center-priority sampling mode can give priority to sampling the central area in the K space. The central area in the K space is usually related to the low-frequency component in the magnetic resonance image. The low-frequency component can represent the basic structural information of the tissue in the magnetic resonance image. Therefore, the use of the center-priority sampling mode helps to quickly generate magnetic resonance images that show the real physical differences between the imaged tissues. The above-mentioned central area may include multiple rows of space located in the middle of the K space. The specific number of rows can be determined by the developer or user based on actual needs, and the embodiment of the present invention does not limit this.

[0095] Each row of data in K-space can correspond to an encoding gradient. The host computer can send the encoding gradient to the gradient coils in the scanner to generate a gradient magnetic field. Magnetic resonance signals generated by this gradient magnetic field can be acquired and populated into the K-space corresponding to the encoding gradient. In this embodiment, magnetic resonance signals can be acquired preferentially based on the encoding gradient corresponding to the central region, achieving center-priority sampling.

[0096] In step S122a, the magnetic resonance image is generated based on the data in the filled K space.

[0097] The data in K-space can be converted into data in the spatial domain through an inverse Fourier transform to obtain a magnetic resonance image. It can be understood that if K-space is a two-dimensional space, a two-dimensional magnetic resonance image can be obtained, and if K-space is a three-dimensional space, multiple two-dimensional magnetic resonance images can be obtained.

[0098] According to the above-described solution of an embodiment of the present invention, magnetic resonance signals of tissues in the imaging region can be acquired using a center-priority sampling mode in K-space. Based on the acquired magnetic resonance signals, data is then filled into the K-space. Finally, the magnetic resonance image is generated based on the data in the filled K-space. Users are generally more interested in data in the central region of K-space. Therefore, the above-described solution utilizes a center-priority sampling mode to fill the K-space, which facilitates the rapid generation of magnetic resonance image sequences that depict realistic physical differences between imaged tissues and better meets the actual needs of users.

[0099] Exemplarily, acquiring magnetic resonance signals of tissues in the imaging region in step S120 and generating the magnetic resonance image based on the acquired magnetic resonance signals may further include steps S123 to S125.

[0100] In step S123, for each target encoding gradient, the following sub-steps 1 and 2 are performed until the data in each row of space corresponding to each target encoding gradient in the filled K-space is updated to obtain updated data. In sub-step 1, magnetic resonance signals are acquired in the imaging region based on the target encoding gradient. In sub-step 2, the data in the row of space corresponding to the target encoding gradient is updated.

[0101] The target encoding gradient may be a phase encoding gradient corresponding to the central region in the K space.

[0102] In step S124, the updated data is subjected to inverse Fourier transform processing to obtain a background image.

[0103] The execution process of this step S124 is similar to that of step S122a and will not be repeated here for the sake of brevity. Steps S123 to S125 are executed after step S122a. As time passes, due to the relaxation phenomenon of hydrogen atoms, the intensity of the signal generated by each tissue in the imaging area will gradually increase toward 1. It can be understood that the execution of steps S121a and S122a requires a certain amount of time. When step S123 is executed, the signal of each tissue has roughly returned to the initial signal intensity. Therefore, the image obtained through steps S123 and S124 can be considered as a background image of the blood vessels in the imaging area.

[0104] In step S125 , the magnetic resonance image is fused with the background image to obtain a fused image.

[0105] The magnetic resonance image and background image can be superimposed and fused using preset coefficients. It should be understood that before fusion, one or both of the magnetic resonance image and background image can be processed using some image processing operations before fusion. For example, such image processing operations may include image enhancement, brightness adjustment, filtering, image segmentation, etc. In one example, maximum projection processing can be performed on the magnetic resonance image to primarily display blood vessels. In other examples, the magnetic resonance image and / or background image can also be processed using minimum projection, 3D segmentation reconstruction, etc. It will be understood that the magnetic resonance image sequence may also include multiple fused images.

[0106] According to the above-described solution of an embodiment of the present invention, the data in the corresponding space in K-space can be updated for each target encoding gradient. The updated data is then subjected to an inverse Fourier transform to obtain a background image. Finally, the magnetic resonance image and the background image are fused to produce a fused image. In this solution, the magnetic resonance image primarily provides blood flow information, while the background image primarily provides background information. Therefore, the resulting fused image provides richer information for user analysis, facilitating qualitative research on the target object.

[0107] Exemplarily, generating the magnetic resonance image based on the acquired magnetic resonance signals in step S120 may include: step S121b and step S122b.

[0108] In step S121b, data filling is performed on the K space based on the acquired magnetic resonance signals.

[0109] The embodiment of the present invention does not limit the specific method of filling the K space with data, which can be determined according to the actual needs of the developer or user. In one example, the center-first sampling mode can also be used to fill the K space with data.

[0110] In step S122b, the magnetic resonance image is generated based on the data in the filled K space by a spatiotemporal joint reconstruction algorithm.

[0111] Spatiotemporal joint reconstruction (also known as spatiotemporal joint reconstruction) algorithms can rapidly generate magnetic resonance images by undersampling data in k-space. For example, spatiotemporal joint reconstruction algorithms can be based on compressed sensing, low-rank matrix / tensor decomposition, deep learning, or golden flip angle. In one example, the spatiotemporal joint reconstruction algorithm can also generate additional magnetic resonance images based on data in populated k-space obtained at different times (e.g., data in k-space used to generate different magnetic resonance images). This can increase the total number of magnetic resonance images in a magnetic resonance image sequence, which helps improve the visual fluency of the magnetic resonance image sequence.

[0112] It is understood that the relevant contents of steps S121a and S122a can also be used in conjunction with the relevant contents of steps S121b and S122b. For example, a center-first sampling mode can be used to fill the K-space with data. A spatiotemporal joint reconstruction algorithm can then be used to undersample the data in the filled K-space to generate a magnetic resonance image.

[0113] According to the above-described solution of an embodiment of the present invention, data can be filled into the K-space based on the acquired magnetic resonance signals. A magnetic resonance image can then be generated using a spatiotemporal joint reconstruction algorithm based on the data in the filled K-space. This solution utilizes the spatiotemporal joint reconstruction algorithm to rapidly generate magnetic resonance images, thereby improving the efficiency of magnetic resonance image generation.

[0114] An embodiment of the present invention also provides a magnetic resonance imaging device. Figure 7 FIG2 shows a schematic block diagram of a magnetic resonance imaging device 200 according to an embodiment of the present invention. Figure 7 As shown, the magnetic resonance imaging apparatus 200 may include a processor 210 and an execution device 220 .

[0115] For each magnetic resonance image to be generated in a magnetic resonance image sequence, the processor 210 is configured to control the execution device 220 to perform the following steps: sequentially generating a slice-selective saturation pulse signal and N inversion pulse signals in a preset time period corresponding to the magnetic resonance image and in at least an imaging region of a target object, wherein the N inversion pulse signals are used to perform a first inversion operation on tissue in at least the imaging region. After or simultaneously with performing the first inversion operation on tissue in at least the imaging region using the reciprocal (i+1)th inversion pulse signal of the N inversion pulse signals, and before performing the first inversion operation on tissue in at least the imaging region using the reciprocal (i)th inversion pulse signal of the N inversion pulse signals, a second inversion operation is performed on blood in a labeled region of the target object, such that the longitudinal magnetization direction of the blood subjected to the second inversion operation is uniformly positive when imaged in the imaging region. N is a non-negative integer. i is a positive odd number less than N. The labeled region is adjacent to the imaging region, and the blood to be imaged flows into the imaging region via the labeled region.

[0116] The processor 210 is configured to control the execution device 220 to execute the following steps: acquiring magnetic resonance signals of tissue in the imaging region.

[0117] The processor 210 is further configured to generate the magnetic resonance image based on the acquired magnetic resonance signals. The later the magnetic resonance image is in the magnetic resonance image sequence, the longer the preset time period corresponding to the magnetic resonance image is.

[0118] Exemplarily, the processor 210 is configured to control the execution device 220 to perform the following steps: when N is a positive odd number, after the slice-selective saturation pulse signal performs saturation processing on tissue in at least the imaging region and before the first inversion pulse signal among the N inversion pulse signals performs a first inversion operation on tissue in at least the imaging region, a first pulse signal is generated in the marking region. The first pulse signal is used to perform a second inversion operation on blood in the marking region.

[0119] Exemplarily, the processor 210 is configured to control the execution device 220 to perform a second inversion operation on the blood in the marked area of ​​the target object, and further configured to generate a first pulse signal in the marked area of ​​the target object, wherein the first pulse signal is used to perform the second inversion operation on the blood in the marked area.

[0120] Exemplarily, the first pulse signal is generated at the end time of generation of the (i+1)th inversion pulse signal from the last, and continues until the start time of generation of the (i)th inversion pulse signal from the last.

[0121] Exemplarily, the processor 210 is configured to control the execution device 220 to perform a second inversion operation on the blood in the marked area of ​​the target object, and is further configured to perform the second inversion operation on the blood in the marked area using the (i+1)th inversion pulse signal from the last digit. The (i+1)th inversion pulse signal from the last digit is generated in at least the imaging area and the marked area.

[0122] Exemplarily, the length of the marking area along the flow direction of the blood to be imaged is greater than or equal to a first product, and the difference between the length of the marking area and the first product is less than a difference threshold, wherein the first product is the product of the time interval between the penultimate (i+1)th inversion pulse signal and the penultimate (i)th inversion pulse signal and the blood flow velocity of the blood to be imaged.

[0123] Exemplarily, the value of N is determined based on the duration of a preset time period corresponding to the magnetic resonance image.

[0124] Exemplarily, the processor 210 is configured to control the execution device 220 to sequentially generate a slice-selected saturation pulse signal and N inversion pulse signals in at least the imaging area of ​​the target object, and is further configured to sequentially generate a slice-selected saturation pulse signal and N inversion pulse signals in the background suppression area of ​​the target object. The background suppression area includes the imaging area. The background suppression area and the imaging area have identical edges adjacent to the marking area, and the length of the background suppression area in the direction of blood flow to be imaged is greater than or equal to the maximum value in the second product. The second product includes the product of the time interval between each two adjacent target pulse signals and the blood flow velocity of the blood to be suppressed. The target pulse signal includes the slice-selected saturation pulse signal and the N inversion pulse signals.

[0125] Exemplarily, the processor 210 is configured to control the execution device 220 to acquire magnetic resonance signals of tissue in an imaging region, and the processor 210 is configured to generate the magnetic resonance image based on the acquired magnetic resonance signals. The execution device 220 is further configured to acquire magnetic resonance signals of tissue in the imaging region based on a center-first sampling mode of K-space. The processor 210 is configured to perform data filling in the K-space based on the acquired magnetic resonance signals, and to generate the magnetic resonance image based on the data in the filled K-space.

[0126] Exemplarily, the processor 210 is configured to control the execution device 220 to acquire magnetic resonance signals of tissue in the imaging region, and to generate the magnetic resonance image based on the acquired magnetic resonance signals. The processor 210 is further configured to control the execution device 220 to perform the following steps for each target encoding gradient until the data in a row of space corresponding to each target encoding gradient in the populated K-space is updated to obtain updated data. The target encoding gradient is the phase encoding gradient corresponding to the central region in K-space. Magnetic resonance signals are acquired in the imaging region based on the target encoding gradient. The data in the row of space corresponding to the target encoding gradient is updated.

[0127] The processor 210 is configured to perform inverse Fourier transform processing on the updated data to obtain a background image, and to fuse the magnetic resonance image with the background image to obtain a fused image.

[0128] Exemplarily, the processor 210 generates the magnetic resonance image based on the acquired magnetic resonance signals, and is further configured to: fill the K-space with data based on the acquired magnetic resonance signals, and generate the magnetic resonance image based on the data in the filled K-space using a spatiotemporal joint reconstruction algorithm.

[0129] According to yet another aspect of the present invention, a nonvolatile storage medium is provided. The nonvolatile storage medium stores program instructions. When executed by a computer or processor, the program instructions cause the computer or processor to perform the corresponding steps of the magnetic resonance angiography method according to an embodiment of the present invention and are used to implement the corresponding modules in the magnetic resonance imaging device according to an embodiment of the present invention or the corresponding modules in the magnetic resonance angiography device. The nonvolatile storage medium may include, for example, a smartphone memory card, a tablet computer storage component, a personal computer hard drive, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a portable compact disc read-only memory (CD-ROM), a USB memory, or any combination of the above nonvolatile storage media. The nonvolatile storage medium may be any combination of one or more computer-readable storage media. According to yet another aspect of the present invention, a computer program product is provided, including computer program instructions. When executed by a computer or processor, the computer or processor causes the computer or processor to perform the corresponding steps of the magnetic resonance angiography method.

[0130] A person skilled in the art can understand the specific implementation scheme of the magnetic resonance imaging device and the non-volatile storage medium by reading the above description of the magnetic resonance angiography method, and for the sake of brevity, it is not repeated here.

[0131] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely illustrative and are not intended to limit the scope of the present invention. Various changes and modifications may be made therein by those skilled in the art without departing from the scope and spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as claimed in the appended claims.

[0132] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0133] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units described is merely a logical functional division. In actual implementation, other division methods may be used. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not implemented.

[0134] In the description provided herein, numerous specific details are described. However, it is understood that embodiments of the present invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0135] Similarly, it should be understood that in order to streamline the present invention and aid in understanding one or more of the various inventive aspects, in the description of exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this approach to the present invention should not be interpreted as reflecting the intention that the claimed invention requires more features than those explicitly recited in each claim. More precisely, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with fewer features than all the features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into the detailed description, with each claim itself serving as a separate embodiment of the present invention.

[0136] It will be understood by those skilled in the art that, except where mutually exclusive, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or apparatus disclosed herein may be combined in any combination. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature providing the same, equivalent, or similar purpose.

[0137] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of the present invention and to form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

[0138] The various component embodiments of the present invention may be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will appreciate that, in practice, a microprocessor or digital signal processor (DSP) may be used to implement some or all of the functions of some modules in a magnetic resonance imaging device according to an embodiment of the present invention. The present invention may also be implemented as a device program (e.g., a computer program or computer program product) for performing part or all of the methods described herein. Such a program implementing the present invention may be stored on a computer-readable medium or in the form of one or more signals. Such signals may be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0139] It should be noted that the above embodiments illustrate rather than limit the invention, and that those skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between brackets should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present invention may be implemented by means of hardware comprising several different elements and by means of appropriately programmed computers. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0140] The foregoing description is merely a specific embodiment of the present invention or an illustration of a specific embodiment. The scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed in the present invention are intended to be encompassed by the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A magnetic resonance angiography method, characterized in that: The method comprises: For each magnetic resonance image to be generated in the magnetic resonance image sequence, In a preset time period corresponding to the magnetic resonance image and in at least an imaging region of the target object, a slice-selective saturation pulse signal and N inversion pulse signals are sequentially generated, wherein the N inversion pulse signals are used to perform a first inversion operation on tissue in at least the imaging region, and after or simultaneously with the first inversion operation on tissue in at least the imaging region using the reciprocal (i+1)th inversion pulse signal among the N inversion pulse signals, and before the first inversion operation on tissue in at least the imaging region using the reciprocal (i)th inversion pulse signal among the N inversion pulse signals, a second inversion operation is performed on blood in a marking region of the target object, so that the longitudinal magnetization direction of the blood subjected to the second inversion operation is positive when imaged in the imaging region, N is a non-negative integer, i is a positive odd number less than or equal to N-1, the marking region is adjacent to the imaging region, and the blood to be imaged flows into the imaging region via the marking region; Acquiring magnetic resonance signals of tissue in the imaging region, and generating the magnetic resonance image based on the acquired magnetic resonance signals; The later the position of the magnetic resonance image in the magnetic resonance image sequence is, the longer the preset time period corresponding to the magnetic resonance image is.

2. The method according to claim 1, wherein The method further comprises: When N is a positive odd number, after the layer-selective saturation pulse signal performs saturation processing on tissue in at least the imaging area and before the first inversion pulse signal among the N inversion pulse signals performs a first inversion operation on tissue in at least the imaging area, another inversion pulse signal is generated in the marking area, wherein the another inversion pulse signal is used to perform a second inversion operation on blood in the marking area.

3. The method according to claim 1, wherein The performing a second inversion operation on the blood in the marked area of ​​the target object includes: Another inversion pulse signal is generated in the marked area of ​​the target object, wherein the other inversion pulse signal is used to perform a second inversion operation on the blood in the marked area.

4. The method according to claim 3, wherein The other inversion pulse signal is generated at the time when the generation of the (i+1)th inversion pulse signal from the last is finished, and continues until the time when the generation of the (i)th inversion pulse signal from the last is started.

5. The method according to claim 1, wherein The performing a second inversion operation on the blood in the marked area of ​​the target object includes: A second inversion operation is performed on the blood in the marking area using the (i+1)th inversion pulse signal from the end, wherein the (i+1)th inversion pulse signal from the end is generated in at least the imaging area and the marking area.

6. The method according to claim 5, wherein The length of the marking area along the flow direction of the blood to be imaged is greater than or equal to a first product, and the difference between the first product and the first product is less than a difference threshold, wherein the first product is the product of the time interval between the penultimate (i+1)th inversion pulse signal and the penultimate (i)th inversion pulse signal and the blood flow velocity of the blood to be imaged.

7. The method according to claim 1, wherein The value of N is determined based on the duration of a preset time period corresponding to the magnetic resonance image.

8. The method according to claim 1, wherein In at least an imaging region of a target object, a slice-selective saturation pulse signal and N inversion pulse signals are sequentially generated, including: A layer-selected saturation pulse signal and N inversion pulse signals are sequentially generated in a background suppression area of ​​the target object, wherein the background suppression area includes the imaging area, the background suppression area and the imaging area have the same edge adjacent to the marking area, and in the flow direction of the blood to be imaged, the length of the background suppression area is greater than or equal to the maximum value in the second product, the second product includes the product of the time interval between each two adjacent target pulse signals and the blood flow velocity of the blood to be suppressed, and the target pulse signal includes the layer-selected saturation pulse signal and the N inversion pulse signals.

9. The method according to claim 1, wherein The acquiring magnetic resonance signals of tissue in the imaging region and generating the magnetic resonance image based on the acquired magnetic resonance signals includes: Based on a center-first sampling mode of K space, magnetic resonance signals of tissue are collected in the imaging region, and data filling is performed on the K space based on the collected magnetic resonance signals; The magnetic resonance image is generated based on the data in the filled K-space.

10. The method according to claim 9, wherein The acquiring of magnetic resonance signals of tissue in the imaging region and generating the magnetic resonance image based on the acquired magnetic resonance signals further includes: For each target encoding gradient, perform the following steps until the data in a row of space corresponding to each target encoding gradient in the filled K space is updated to obtain updated data, wherein the target encoding gradient is the phase encoding gradient corresponding to the central region in the K space: acquiring magnetic resonance signals in the imaging region based on the target encoding gradient; Update the data in a row of space corresponding to the target encoding gradient; Performing inverse Fourier transform processing on the updated data to obtain a background image; The magnetic resonance image is fused with the background image to obtain a fused image.

11. The method according to any one of claims 1 to 10, characterized in that Generating the magnetic resonance image based on the acquired magnetic resonance signal includes: Filling the K space with data based on the acquired magnetic resonance signals; The magnetic resonance image is generated based on the data in the filled K space through a spatiotemporal joint reconstruction algorithm.

12. A magnetic resonance imaging device, characterized in that: The apparatus includes a processor and an execution device, wherein for each magnetic resonance image to be generated in a magnetic resonance image sequence, the processor is configured to control the execution device to perform the following steps: In a preset time period corresponding to the magnetic resonance image and in at least an imaging region of the target object, a slice-selective saturation pulse signal and N inversion pulse signals are sequentially generated, wherein the N inversion pulse signals are used to perform a first inversion operation on tissue in at least the imaging region, and after or simultaneously with performing the first inversion operation on tissue in at least the imaging region using the reciprocal (i+1)th inversion pulse signal among the N inversion pulse signals, and before performing the first inversion operation on tissue in at least the imaging region using the reciprocal (i)th inversion pulse signal among the N inversion pulse signals, a second inversion operation is performed on blood in a marking region of the target object, so that the longitudinal magnetization direction of the blood subjected to the second inversion operation is positive when imaged in the imaging region, N is a non-negative integer, i is a positive odd number less than N, the marking region is adjacent to the imaging region, and the blood to be imaged flows into the imaging region via the marking region; acquiring magnetic resonance signals of tissue in the imaging region; The processor is further configured to generate the magnetic resonance image based on the acquired magnetic resonance signals; The later the position of the magnetic resonance image in the magnetic resonance image sequence is, the longer the preset time period corresponding to the magnetic resonance image is.

13. A non-volatile storage medium storing computer program instructions, characterized in that: The computer program instructions are used to execute the magnetic resonance angiography method according to any one of claims 1 to 11 when executed.

14. A computer program product comprising computer program instructions, characterized in that When the computer program instructions are executed by a processor, the computer program instructions are used to perform the magnetic resonance angiography method according to any one of claims 1 to 11.

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