Magnetic resonance angiography method and magnetic resonance imaging device

Abstract

The application provides a magnetic resonance angiography method and a magnetic resonance imaging device, the magnetic resonance angiography method comprising: for each magnetic resonance image to be generated in a magnetic resonance image sequence, sequentially generating a layer selection 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, the N inversion pulse signals being used for performing a first inversion operation on tissues in the at least imaging region; after or simultaneously with performing the first inversion operation on the tissues in the at least imaging region by using an (N-i+1)th inversion pulse signal, and before performing the first inversion operation on the tissues in the at least imaging region by using an (N-i)th inversion pulse signal, performing a second inversion operation on blood in a labeling region; collecting a magnetic resonance signal of the tissues in the imaging region, and generating the magnetic resonance image. In the above scheme, the total time consumption of the magnetic resonance imaging process is shorter, and the imaging efficiency is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of data processing technology, and more specifically to a magnetic resonance angiography method, a magnetic resonance imaging device, a non-volatile storage medium, and a computer program product. Background Technology

[0002] Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging technique that uses radiofrequency pulses and gradient magnetic fields to generate detailed images of the internal structures of the human body. Unlike X-ray or CT scans, MRI does not use ionizing radiation, making it safer for the subject. Based on 4D MRI technology, a sequence of MRI images, comprising multiple images, can be generated over a period of time. This sequence allows for the observation of continuous changes in the internal tissue structure of the object being imaged.

[0003] To improve the visibility of blood in certain areas of an imaging subject, traditional 4D magnetic resonance imaging (MRI) often relies on the use of contrast agents (such as gadolinium-based contrast agents). While this approach increases the contrast of MRI images, contrast agents can place a metabolic burden on the kidneys of the imaging subject. Furthermore, the use of contrast agents increases imaging costs. In other approaches, MRI images can be generated based on subtraction techniques to form an MRI image sequence. However, using subtraction techniques requires acquiring two independent imaging datasets to generate a single MRI image within the sequence. Therefore, this imaging process is time-consuming and inefficient. On the one hand, this severely impacts the patient's experience. On the other hand, the imaging subject struggles to maintain a stable pose during prolonged imaging. Changes in pose lead to poor contrast in the MRI images obtained through subtraction. Summary of the Invention

[0004] The present invention was proposed in view of the above-mentioned 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 method comprising: for each magnetic resonance image to be generated in a magnetic resonance image sequence, during a preset time period corresponding to the magnetic resonance image and in at least the imaging region of 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 (i+1)th inverse of the N inversion pulse signals, and while performing the first inversion operation on tissue in at least the imaging region using the (i+1)th inverse of the N inversion pulse signals, a layer-selected saturation pulse signal and N inversion pulse signals are sequentially generated. Before performing a first inversion operation on at least the tissue in the imaging region using i inversion pulse signals, a second inversion operation is performed on the blood in the marked region of the target object, so that the longitudinal magnetization direction of the blood after the second inversion operation is positive when it is 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 marked region is adjacent to the imaging region and the blood to be imaged flows into the imaging region through the marked region; magnetic resonance signals of the tissue in the imaging region are acquired, and the 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, the longer the preset time period corresponding to the magnetic resonance image.

[0006] For example, the above-described magnetic resonance angiography method further includes:

[0007] When N is a positive odd number, after the layer-selected saturation pulse signal saturates the tissue in at least the imaging region, and before the first inversion pulse signal in the N inversion pulse signals performs a first inversion operation on the tissue in at least the imaging region, another inversion pulse signal is generated in the marker region, wherein the other inversion pulse signal is used to perform a second inversion operation on the blood in the marker region.

[0008] For example, performing a second inversion operation on blood in a marked region of a target object includes:

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

[0010] For example, the additional inverted pulse signal is generated at the end of the generation of the (i+1)th inverted pulse signal from the end, and continues until the start of the generation of the ith inverted pulse signal from the end.

[0011] For example, performing a second inversion operation on blood in a marked region of a target object includes:

[0012] A second inversion operation is performed on the blood in the marked region 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 region and the marked region.

[0013] For example, the length of the marked region along the flow direction of the blood to be imaged is greater than or equal to the first product, and the difference between the marked region and the first product is less than the difference threshold, wherein the first product is the product of the time interval between the (i+1)th inverted pulse signal and the i-th inverted pulse signal and the blood flow velocity of the blood to be imaged.

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

[0015] For example, in at least the imaging region of the target object, a layer-selected saturation pulse signal and N inverted pulse signals are sequentially generated, including:

[0016] Layer-selected saturated pulse signals and N inverted pulse signals are sequentially generated in the background suppression region of the target object. The background suppression region includes the imaging region. The background suppression region and the imaging region have the same edge that is adjacent to the marker region. In the direction of blood flow to be imaged, the length of the background suppression region is greater than or equal to the maximum value in the second product. The second product includes the product of the time interval between every two adjacent target pulse signals and the blood flow velocity of the blood to be suppressed. The target pulse signals include layer-selected saturated pulse signals and N inverted pulse signals.

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

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

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

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

[0021] For each target coding gradient, perform the following steps until the data in each row of space corresponding to each target coding gradient in the filled K-space is updated to obtain the updated data, where the target coding gradient is the phase coding 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 one row space corresponding to the target encoding gradient;

[0024] The updated data is then subjected to an inverse Fourier transform to obtain the background image.

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

[0026] For example, generating the magnetic resonance image based on the acquired magnetic resonance signal includes:

[0027] Based on the acquired magnetic resonance signals, data is filled into the K-space;

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

[0029] According to another aspect of the present invention, a magnetic resonance imaging (MRI) apparatus is also provided, comprising a processor and an execution device. For each MRI image to be generated in a sequence of MRI images, the processor is configured to control the execution device to perform the following steps: during a preset time period corresponding to the MRI image and within at least the imaging region of 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 (i+1)th inverse inversion pulse signal from the N inversion pulse signals, and while using the N inversion pulse signals... Before the i-th inverse inverse pulse signal in the inverse pulse signal performs a first inverse operation on the tissue in at least the imaging region, a second inverse operation is performed on the blood in the marked region of the target object, so that the longitudinal magnetization direction of the blood after the second inverse operation is positive when it is imaged in the imaging region. N is a non-negative integer, i is a positive odd number less than N, the marked region is adjacent to the imaging region and the blood to be imaged flows into the imaging region through the marked region; magnetic resonance signals of the tissue in the imaging region are acquired; the processor is also 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, the longer the preset time period corresponding to the magnetic resonance image.

[0030] According to another aspect of the present invention, a non-volatile storage medium is also provided. Program instructions are stored on this non-volatile storage medium, which, when executed, are used to perform the aforementioned magnetic resonance angiography method.

[0031] According to another aspect of the present invention, a computer program product is also provided. This computer program product includes computer program instructions that, when executed by a processor, are used to perform the aforementioned magnetic resonance angiography method.

[0032] According to the above-described solution of the present invention, on the one hand, no contrast agent is needed, which is more health-friendly to the target object and lower in cost; in addition, no subtraction technique is needed, so the total time of the magnetic resonance imaging process in the above solution is shorter, significantly improving imaging efficiency and also helping to reduce the impact of the target object's pose change on the imaging contrast of the magnetic resonance image. Furthermore, the duration of the preset time period corresponding to each magnetic resonance image varies, and compared to solutions using a fixed-length preset time period, the imaging efficiency of the solution provided by the present invention is also higher. Attached Figure Description

[0033] The above and other objects, features, and advantages of the present invention will become more apparent from the more detailed description of the embodiments of the invention in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same parts or steps.

[0034] Figure 1 A schematic flowchart of a magnetic resonance angiography method according to an embodiment of the present invention is shown;

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

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

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

[0038] Figure 5 A schematic diagram of magnetic resonance images a2 to e2 in a magnetic resonance image sequence according to an embodiment of the present invention is shown;

[0039] Figure 6 A schematic diagram illustrating the generation process of a magnetic resonance image f according to an embodiment of the present invention is shown;

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

[0041] To make the objectives, technical solutions, and advantages of the present invention more apparent, exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely a part of the embodiments of the present invention, and not all of the embodiments of the present invention. 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 herein, all other embodiments obtained by those skilled in the art without inventive effort should fall within the protection scope of the present invention.

[0042] To at least partially solve the above problems, embodiments of the present invention provide a magnetic resonance angiography method. Figure 1 A schematic flowchart of a magnetic resonance angiography method according to an embodiment of the present invention is shown. 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 layer-selected saturation pulse signal and N inversion pulse signals are generated sequentially in the preset time period corresponding to the magnetic resonance image and in at least the imaging area of ​​the target object.

[0044] A magnetic resonance imaging (MRI) image sequence may include multiple MRI images to be generated. With each MRI image generated, a user can determine the actual blood flow in a target object by viewing the MRI image sequence. It can be understood that an MRI image sequence may be a video comprising multiple MRI images.

[0045] For example, magnetic resonance imaging (MRI) equipment can be used to acquire magnetic resonance signals for a target object. The target object can be a subject requiring MRI. The MRI equipment may include a scanner, an examination platform, and a host computer. The scanner has space to accommodate the examination platform. The target object can lie flat on the examination platform, and then the examination platform can be moved to the space. Hydrogen atoms in the target object's tissue are subjected to the magnetic force of the main magnetic field (or BO magnetic field), which can be viewed from a macroscopic perspective as the direction of the net magnetization vector formed by several hydrogen atoms being close to the Z-axis direction. The Z-axis direction can be the direction from the head placement area to the foot placement area in the examination platform. The head placement area can be used to place the head of the target object, and the foot placement area can be used to place the feet of the target object. After applying a radio frequency pulse signal (e.g., the layer-selected saturation pulse signal and the inversion pulse signal in the embodiments of this application) to at least the imaging area of ​​the target object, some hydrogen atoms in the applied area will absorb energy and transition from a low energy state to a high energy state. From a macroscopic perspective, this can be manifested as a change in the direction of the net magnetization vector. After the radio frequency pulse signal is applied, the high-energy hydrogen atoms undergo relaxation, 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, where it is used to generate a magnetic resonance image through a magnetic resonance imaging algorithm.

[0046] The imaging region of the target object can be a portion of the target object's body that the user wishes to observe. For example, if the user wishes to observe the head of the target object, the imaging region can be the head region or a portion of the head region. Similarly, if the user wishes to observe the kidneys of the target object, the imaging region can be the kidney region or a portion of the kidney region. It is understood that the user can also select the imaging region of the target object according to actual needs, and this embodiment of the invention does not impose limitations.

[0047] Each magnetic resonance imaging (MRI) image to be generated may correspond to a different preset time period. For each MRI image to be generated, the later the MRI image is in the MRI image sequence, the longer the preset time period corresponding to that MRI image.

[0048] For each magnetic resonance imaging (MRI) image to be generated, the preset time period corresponding to that MRI image may include a period from a first time point to a second time point. The first time point is the start time of generating the layer-selected saturation pulse signal used to generate the MRI image. The second time point is the start time of signal acquisition for that MRI image. Taking a MRI image a1 in a sequence as an example, the preset time period is 1000 milliseconds. MRI image a1 can be used to display blood newly flowing into the imaging area within 1000 milliseconds. Taking the last MRI image e1 in a sequence as an example, the preset time period is 2000 milliseconds. MRI image e1 can be used to display blood newly flowing into the imaging area within 2000 milliseconds. Since the preset time period is longer the later an MRI image is in the sequence, MRI image e1 can be located after MRI image a1. It is understood that the two images can also be non-adjacent, meaning there can be at least one MRI image between them. When viewing the above MRI image sequence, the user can observe the process of blood continuously being injected into the blood vessels in the imaging area. It is understandable that the specific duration of the preset time period corresponding to each magnetic resonance image to be generated can be set by developers or users according to actual needs. For example, the smaller the duration difference between the preset time periods of adjacent magnetic resonance images, the more magnetic resonance images can be in the magnetic resonance sequence, and the smoother the visual effect of blood flowing into the blood vessels in the imaging area.

[0049] The aforementioned layer-select saturation pulse signal can be used to adjust the direction of the net magnetization vector to be close to the X-axis direction. The X-axis direction can be the direction from the left-hand placement area to the right-hand placement area in the examination platform. The left-hand placement area can be used to place the left hand of the target object, and the right-hand placement area can be used to place the right hand of the target object. Through this process, the components of the net magnetization vector in the plane containing the X and Y axes will increase. With the precession of hydrogen atoms, a time-varying magnetic resonance signal can be generated. The Y-axis can be the vertical axis. For example, if the signal intensity of the untreated magnetic resonance signal corresponding to blood (hereinafter referred to as the signal) is taken as 1 (greater than 0 can be considered as positive in the longitudinal magnetization direction, which can be considered as the direction of the projection of the net magnetization vector in the Z-axis direction), and the signal intensity after applying the reverse pulse signal to the blood is taken as -1 (less than 0 can be considered as negative in the longitudinal magnetization direction), then ideally, the layer-select saturation pulse signal can adjust the signal intensity of the signal generated by the tissue in the application area to 0. It can be understood that the tissue in the application area can include solid tissues, such as fat and brain tissue, and can also include fluid tissues, such as blood and cerebrospinal fluid. Therefore, background signal suppression can be achieved through this layer-selective saturation pulse signal. It can be understood that the aforementioned layer-selective saturation pulse signal may include a single pulse or multiple pulses.

[0050] In one example, a layer-selective saturation pulse signal can be generated only within the imaging region. In another example, a layer-selective saturation pulse signal can also be generated in a region larger than the imaging region. This larger region includes at least the imaging region. Applying the layer-selective saturation pulse signal to a larger region can more effectively suppress the signal of solid tissue to near zero, thereby reducing its impact on image quality. This can also suppress background signals for venous blood, whose flow direction is opposite to that of arterial blood. Furthermore, it ensures that even if the tissue is located at the edge of the imaging region, its signal is adequately suppressed, thereby avoiding signal contamination caused by edge effects. Developers can determine the application region of the layer-selective saturation pulse signal according to actual needs, and the embodiments of the present invention are not limited thereto. For ease of description, the application region of the layer-selective saturation pulse signal is referred to below as the background suppression region of the target object.

[0051] N inversion pulse signals can be used to perform a first inversion operation on at least the tissue in the imaging region. N can be a non-negative integer. In one example, N can also be 0. Specifically, for example, signals for generating a magnetic resonance image can be acquired after the tissue in at least the imaging region has been saturated by a slice-select saturation pulse signal, without generating any inversion pulse signals. This magnetic resonance image can be a relatively early magnetic resonance image in a magnetic resonance image sequence.

[0052] Similar to the layer-select saturation pulse signal, the aforementioned inverted pulse signal can be generated only within the imaging region. Alternatively, the aforementioned inverted pulse signal can also be generated in a region larger than the imaging region. This larger region includes the imaging region. It is understood that the application region of the aforementioned inverted pulse signal can be the same as or different from the application region of the aforementioned layer-selected saturation pulse signal. For ease of description, the following embodiments will use the example where both are applied in the same background suppression region.

[0053] From a macroscopic perspective, the aforementioned 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 located in the application region of the inversion pulse signal. For example, through the aforementioned first inversion operation, the direction of the net magnetization vector can be reversed by 180 degrees. After a suitable inversion recovery time (TI), the intensity of the net magnetization vector can approach zero. Therefore, the aforementioned inversion pulse signal can also be used for selective background signal suppression. It is understood that the aforementioned inversion pulse signal may include a single pulse or multiple pulses. The target parameters (e.g., pulse frequency, pulse duration, pulse intensity, etc.) of multiple inversion pulse signals can be the same.

[0054] In one example, N could be 4. See also Figure 2 , Figure 2A schematic diagram of a magnetic resonance angiography method according to an embodiment of the present invention is shown. (Combined with...) Figure 2 If the inverted pulse signals are arranged in reverse chronological order, then the N inverted pulse signals can include inverted pulse signals 1 to 4. Specifically, for example, taking the time point of magnetic resonance signal acquisition as time 0, the generation start time of the layer-selected saturation pulse signal can be -2000 milliseconds, the generation start time of inverted pulse signal 4 can be approximately -1652.1 milliseconds, the generation start time of inverted pulse signal 3 can be approximately -987.7 milliseconds, the generation start time of inverted pulse signal 2 can be approximately -435.8 milliseconds, and the generation start time of inverted pulse signal 1 can be approximately -107 milliseconds. The time period from the generation start time of the layer-selected saturation pulse signal to time 0 can be the preset time 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 the tissue in at least the imaging region using the (i+1)th inversion pulse signal out of N inversion pulse signals, and before performing the first inversion operation on the tissue in at least the imaging region using the ith inversion pulse signal out of N inversion pulse signals, a second inversion operation can be performed on the blood in the marked region of the target object. This second inversion operation ensures that the longitudinal magnetization direction of the blood after this operation is positive when it is 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 layer-selection saturation pulse signal saturates the tissue in at least the imaging region, and before the inversion pulse signal performs the first inversion operation on the tissue in at least the imaging region, an additional inversion pulse signal (an additional inversion pulse signal relative to the N inversion pulse signals, hereinafter referred to as the first pulse signal) can be generated in the marked region. It can 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+1)th inversion pulse signal mentioned above does not exist. See also... Figure 3 , Figure 3 A schematic diagram of a magnetic resonance angiography method according to an embodiment of the present invention is shown. Figure 3In the example, N is 1. A first pulse signal h can be generated in the marked region after the layer-selection saturation pulse signal saturates the tissue in at least the imaging region, and before the inversion pulse signal 1 performs a first inversion operation on the tissue in at least the imaging region. No other inversion pulse signals may be generated between the start time of the generation of the inversion pulse signal 1 and the start time of signal acquisition (refer to the start time of imaging in the figure). Specifically, in this example, blood flowing into the imaging region from the end time of the generation of the layer-selection saturation pulse signal to the start time of the generation of the inversion pulse signal 1 initially has a positive longitudinal magnetization direction. This blood first undergoes a second inversion operation of the first pulse signal h in the marked region, and then undergoes a first inversion operation of the inversion pulse signal 1 in the imaging region. Therefore, the longitudinal magnetization direction of this blood is positive when it is imaged in the imaging region.

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

[0058] See Figure 4 , Figure 4 A schematic diagram illustrating a marker region, an imaging region, and a background suppression region according to an embodiment of the present invention is shown. Figure 4 Taking a portion of the brain region as the target area for imaging as an example. 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 marked area mentioned above. Figure 4 The example also shows an imaging region of the target object's kidney. In this example, arterial blood to be imaged flows from the heart through the abdominal aorta into the kidney region. The heart is located above the kidney region. Therefore, in this example, the area above the kidney region can be used as the marked region. Similarly, Figure 4 The example also illustrates an imaging area where the target object's hip bone region is the imaging area. In this example, the area above the hip bone region can be used as the aforementioned marked area. The specific locations of the marked area and imaging area can be determined by the developer or user, and this embodiment of the invention does not impose any limitations. It is understood that the blood to be imaged can be arterial blood or venous blood.

[0059] Continue reading Figure 2In the example where N equals 4, i can be 1 or 3. For example, after the first inversion operation is performed on the tissue in at least the imaging region by the inversion pulse signal 2 (the (i+1)th inversion pulse signal from the end in this example, assuming i is 1), 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 for the second inversion operation). As another example, after the first inversion operation is performed on the tissue in at least the imaging region by the inversion pulse signal 4 (the (i+1)th inversion pulse signal from the end in this example, assuming i is 3), 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 for the second inversion operation).

[0060] Since the marked area is adjacent to the imaging area, and the blood to be imaged flows into the imaging area through the marked area, a pre-reversal operation, i.e., a second reversal operation, is performed on the blood to be injected into the imaging area within a preset time period before imaging. Thus, under the combined effect of the first and second reversal operations, the longitudinal magnetization direction of the blood flowing into the imaging area 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, the magnetic resonance signal of the tissue in the imaging area is acquired, and the magnetic resonance image is generated based on the acquired magnetic resonance signal.

[0061] For each magnetic resonance image to be generated in a magnetic resonance image sequence, magnetic resonance signals of the tissue in the imaging region can be acquired after the corresponding period of the magnetic resonance image ends. In some examples, multiple preset phase-encoded gradients can be sequentially used in at least the imaging region through gradient coils in the scanner to sequentially form multiple gradient magnetic fields. Each phase-encoded gradient can correspond to a row in K-space. The magnetic resonance signals acquired in the gradient magnetic fields formed based on the phase gradient encoding can be filled into the row in K-space corresponding to that phase gradient encoding. The data in the filled K-space can be converted into a magnetic resonance image through inverse Fourier transform. In one example, only the magnetic resonance signals corresponding to a portion of the K-space can be acquired, and then the unfilled spaces in K-space can be filled in using a preset algorithm based on the conjugate symmetry of K-space. Then, a magnetic resonance image is generated using the data in the now fully filled K-space. It is understood that if 3D imaging technology is used, the data in K-space can be acquired in blocks sequentially, and this embodiment of the invention is not limited thereto.

[0062] In some embodiments, various magnetic resonance imaging techniques can be used to generate magnetic resonance images. For example, MP-RAGE imaging (Magnetization Prepared Rapid Gradient Echo, an imaging technique using gradient echo sequences), GRE imaging (Gradient Recalled Echo, an imaging technique using short radio frequency pulse signals to generate echo signals), FSE imaging (Fast Spin Echo, an imaging technique using conventional spin echo sequences), bSSFP imaging (balanced Steady State Free Precessing), and stack-of-star golden angle sampling imaging techniques, etc.

[0063] In one example, the magnetic resonance image can be processed and displayed using image processing algorithms. For instance, feature enhancement and noise suppression can be performed on the magnetic resonance image. Another example is the use of region segmentation algorithms or models to determine the region of interest within the magnetic resonance image.

[0064] See Figure 5 , Figure 5 A schematic diagram of magnetic resonance images a2 to e2 in a magnetic resonance image sequence according to an embodiment of the present invention is shown. Figure 5 The solid rectangle in the image represents the background suppression region mentioned above. The dashed rectangle represents the imaging region mentioned above. The grid region represents the marker region mentioned above. In the magnetic resonance images a2 to e2, the area occupied by blood flowing into the imaging region during the preset time period increases with the duration of the preset time period. As magnetic resonance images are continuously generated, the user can view the blood injection process in the blood vessels of the imaging region through the magnetic resonance image sequence.

[0065] According to the above-described solution of the present invention, on the one hand, no contrast agent is needed, which is more health-friendly to the target object and lower in cost; in addition, no subtraction technique is needed, so the total time of the magnetic resonance imaging process in the above solution is shorter, significantly improving imaging efficiency and also helping to reduce the impact of the target object's pose change on the imaging contrast of the magnetic resonance image. Furthermore, the duration of the preset time period corresponding to each magnetic resonance image varies, and compared to solutions using a fixed-length preset time period, the imaging efficiency of the solution provided by the present invention is also higher.

[0066] For example, the above-described magnetic resonance angiography method further includes: when N is a positive odd number, after the slice-selected saturation pulse signal saturates the tissue in at least the imaging region, and before the first inversion pulse signal in the N inversion pulse signals performs a first inversion operation on the tissue in at least the imaging region, generating another inversion pulse signal (hereinafter referred to as the first pulse signal) in the marked region.

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

[0068] According to the above-described scheme of the present invention, when N is a positive odd number, after the layer-selection saturation pulse signal saturates the tissue in at least the imaging region, and before the first inversion pulse signal in the N inversion pulse signals performs a first inversion operation on the tissue in at least the imaging region, a first pulse signal can be generated in the marked region. The above scheme can utilize the first pulse signal to perform a second inversion operation on the blood flowing through the marked region after the generation of the layer-selection saturation pulse signal and before the generation of the first inversion pulse signal. This ensures that the longitudinal magnetization direction of the blood after the second inversion operation is positive when imaged in the imaging region. The above scheme can improve the display effect of magnetic resonance images, and further improve the display effect of magnetic resonance image sequences.

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

[0070] In one example, for each magnetic resonance image to be generated, the value of N can be determined by combining 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 the target duration. The target duration can be the sum of the pulse durations of the layer-selected saturation pulse signal and the N inversion pulse signals. For example, for a magnetic resonance image located relatively early in the magnetic resonance image sequence, the magnetic resonance image signal can be acquired immediately after the layer-selected saturation pulse signal saturates at least the tissue in the imaging region. As another example, for a magnetic resonance image located relatively late in the magnetic resonance image sequence, after the layer-selected saturation pulse signal saturates at least the tissue in the imaging region, the N inversion pulse signals are used to perform a first inversion operation on these tissues before the magnetic resonance image signal is acquired. The longer the preset time period corresponding to these magnetic resonance images, the larger the value of N can be; otherwise, the opposite is true. For any pair of adjacent magnetic resonance images in the magnetic resonance image sequence, the value of N corresponding to the earlier magnetic resonance image can be less than or equal to the value of N corresponding to the later magnetic resonance image.

[0071] According to the above-described scheme of the present invention, for each magnetic resonance image to be generated in the magnetic resonance image sequence, the value of N can be determined based on the duration of a preset time period corresponding to that magnetic resonance image. The value of N in the above scheme is more flexible, which can improve the adaptability of the magnetic resonance angiography method. This also helps to improve the display effect of the magnetic resonance images and the display effect of the magnetic resonance image sequence.

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

[0073] The background suppression region may include the imaging region. Both the background suppression region and the imaging region share the same edges that are adjacent to the marked region. (Continue to refer to...) Figure 4 In the example where the imaging region is a brain region, the lower edge of the background suppression region and the imaging region are the same edge, which is adjacent to the labeled region. In the examples where the imaging regions are the kidney region and the hip region, respectively, the upper edge of the background suppression region and the imaging region are the same edge, which is adjacent to the labeled region.

[0074] For ease of understanding, in this embodiment of the invention, the layer-selected saturation pulse signal and the N inverted pulse signals are collectively referred to as the target pulse signal. The second product includes the product of the time interval between any two adjacent target pulse signals and the blood flow velocity of the blood to be suppressed. For example, continuing 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 inverted pulse signal 4 and the blood flow velocity of the blood to be suppressed, the product of the time interval between the inverted pulse signal 4 and the inverted pulse signal 3 and the blood flow velocity of the blood to be suppressed, etc. In the direction of blood flow to be imaged, the length of the background suppression region is greater than or equal to the maximum value in the second product. This ensures that the signals of all blood flowing into the imaging region to be suppressed can be sufficiently 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 interested in. For example, if the user is interested in the flow state of arterial blood in the brain, the aforementioned blood to be suppressed may include venous blood in the brain.

[0075] According to the above-described scheme of the present invention, a layer-selected saturated pulse signal and N inverted pulse signals can be sequentially generated in the background suppression region of the target object. The background suppression region may include the imaging region and other regions. Since the effective range of the saturated pulse signal and the N inverted pulse signals is larger than that of the imaging region, the interference of the background signal is reduced, the signal-to-noise ratio is improved, and thus the imaging contrast of the blood to be imaged can be improved. This is beneficial to improving the display effect of magnetic resonance images, and thus improving the display effect of magnetic resonance image sequences. In addition, the background suppression region of the above-described size also avoids artifacts in magnetic resonance images and avoids unnecessary increases in scanning time and computational resource consumption.

[0076] For example, the second inversion operation on the blood in the marked area of ​​the target object may include: generating an additional inversion pulse signal (hereinafter referred to as a first pulse signal) in the marked area of ​​the target object. The first pulse signal can be used to perform the second inversion operation on the blood in the marked area. The second inversion operation can be used to invert the direction of the net magnetization vector formed by the tissue in the marked area. For example, the second inversion operation can invert the direction of the net magnetization vector by 180 degrees. In one example, the target parameter of the first pulse signal may be the same as the target parameter of the inversion pulse signal used in step S110 to perform the first inversion operation. In another example, pulse signals with different pulse types that can invert the direction of the net magnetization vector may also be used. The first pulse signal may include a single pulse or multiple pulses, which is not limited in this embodiment of the invention.

[0077] The above text Figure 2 In the relevant examples, a first pulse signal for performing the second inversion operation is generated between the time of generating inversion pulse signal 1 (i.e., -107 ms) and the time of generating inversion pulse signal 2 (i.e., -435.8 ms). A first pulse signal for performing the second inversion operation is also generated between the time of generating inversion pulse signal 3 (i.e., -987.7 ms) and the time of generating inversion pulse signal 4 (i.e., -1652.1 ms). Arterial blood flowing into the imaging region during the time period from time 0 to time -107 ms does not experience any inversion pulse signals. Arterial blood flowing into the imaging region during the time periods from time -435.8 ms to time -987.7 ms and before time -1652.1 ms has experienced an even number of inversion pulse signals applied to the background suppression region up to time 0. For arterial blood flowing into the imaging region between -107 ms and -435.8 ms, by time 0, it not only experienced the inversion pulse signal 1 applied to the background suppression region, but also the first pulse signal applied to the marker region before flowing into the background suppression region. In other words, a pre-inversion operation (i.e., a second inversion operation) was performed on the arterial blood in the imaging region between -107 ms and -435.8 ms during its flow through the marker region. Similarly, for arterial blood flowing into the imaging region between -1652.1 ms and -987.7 ms, by time 0, it successively experienced the first pulse signal, inversion pulse signal 3, inversion pulse signal 2, and inversion pulse signal 1 in the marker region. Thus, by time 0, all arterial blood in the imaging region experienced an even number of inversion pulse signals. This ensures that the blood flowing into the imaging region successively has a positive signal at time 0 and maintains sufficient signal strength.

[0078] According to the above-described scheme 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 the second inversion operation on the blood in the marked region, which is beneficial for improving the display effect of the magnetic resonance image. This also helps to improve the display effect of the magnetic resonance image sequence.

[0079] For example, an additional inverted pulse signal (hereinafter referred to as the first pulse signal) is generated at the end of the generation of the (i+1)th inverted pulse signal from the end, and continues until the start of the generation of the ith inverted pulse signal from the end.

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

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

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

[0083] According to the above-described scheme 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 end and continues until the start of the generation of the ith inversion pulse signal from the end. This scheme, by using a first pulse signal with a longer duration, improves the pre-inversion effect of the blood to be imaged, which is beneficial for enhancing the imaging contrast of the blood. This is beneficial for improving the display effect of magnetic resonance images, and thus improving the display effect of magnetic resonance image sequences.

[0084] For example, the above-described second inversion operation on the blood in the marked area of ​​the target object may include: using the (i+1)th inversion pulse signal from the end to perform the second inversion operation on the blood in the marked area.

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

[0086] Continue reading Figure 2 The blood in the marked area can be reversed using inversion pulse signal 4 and inversion pulse signal 2 (the (i+1)th inversion pulse signal from the end in this example, where i can be 3 or 1). In this example, the first pulse signal is not required. See further... Figure 6 The blood in the marked area can be reversed using the inversion pulse signal 2 (the (i+1)th inversion pulse signal from the end in this example, where i can be 1). In this example, no other inversion pulse signal is needed to perform the second inversion operation besides using the first pulse signal f.

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

[0088] For example, the length of the marked region along the flow direction of the blood to be imaged is greater than or equal to the first product, and the difference between the marked region and the first product is less than the difference threshold.

[0089] The first product can be the product of the time interval between the (i+1)th and ith inverted pulse signals from the end and the blood flow velocity of the blood to be imaged. The specific value of the difference threshold can be determined by the developers according to actual needs. By setting the difference threshold, the size of the marked area can be ensured to be reasonable.

[0090] The background suppression region can be extended by the length of the first product towards the source of the blood to be imaged, thereby expanding the effective range of the (i+1)th inversion pulse signal from the end. For example, if the blood flow velocity of the blood flow to be imaged is 0.03 cm per millisecond, and the aforementioned time interval is 300 milliseconds, then the first product can be 9 cm (i.e., 0.03 * 300). The background suppression region of the inversion pulse signal can be extended by 9 cm to pre-reverse the longitudinal magnetization direction of the blood about to flow into the imaging region using the (i+1)th inversion pulse signal from the end. It can be understood that the time interval between the (i+1)th inversion pulse signal from the end and the ith inversion pulse signal from the end can vary with i. In other words, the aforementioned length of the marked region can be different for different inversion pulse signals. The above scheme allows for flexible configuration of the effective range of the inversion pulse signal based on the first product.

[0091] According to the above-described solution of the present invention, on the one hand, the second inversion operation can be performed using the (i+1)th inversion pulse signal from the end, thereby reducing the total number of inversion pulse signals generated, which is beneficial for reducing the configuration cost of magnetic resonance imaging equipment and improving the adaptability of magnetic resonance angiography to 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] For example, the acquisition of magnetic resonance signals of tissue in the imaging region in step S120, and the generation of the magnetic resonance image based on the acquired magnetic resonance signals, may include steps S121a and S122a.

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

[0094] K-space can be used to store magnetic resonance imaging (MRI) data in the frequency domain. In MRI, acquired data is filled into K-space, and then the data in the frequency domain is converted to data in the spatial domain (or image domain) to obtain the MRI image. The center-first sampling mode described above prioritizes sampling the central region in K-space. The central region in K-space is typically associated with low-frequency components in the MRI image. These low-frequency components can represent the basic structural information of the tissue in the MRI image. Therefore, using the center-first sampling mode helps to quickly generate MRI images that show the true physical differences between the imaging tissues. The aforementioned central region may include multiple rows of space located in the middle of K-space. The specific number of rows can be determined by the developers or users based on actual needs, and this embodiment of the invention does not impose any limitations.

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

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

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

[0098] According to the above-described scheme of the present invention, magnetic resonance signals of tissue can be acquired in the imaging region based on the center-first sampling mode of K-space. Data filling is performed on the K-space based on the acquired magnetic resonance signals. Finally, the magnetic resonance image is generated based on the data in the filled K-space. Users are typically more concerned with the data in the central region of K-space. Therefore, the above scheme uses a center-first sampling mode to fill the K-space, which is beneficial for quickly generating magnetic resonance image sequences that show the true physical differences between the imaging tissues, and also better meets the actual needs of users.

[0099] For example, step S120, which involves acquiring magnetic resonance signals of tissue in the imaging region 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 coding gradient, sub-steps 1 and 2 are performed until the data in each row of space corresponding to each target coding gradient in the filled K-space is updated to obtain the updated data. In sub-step 1, magnetic resonance signals are acquired in the imaging region based on the target coding gradient. In sub-step 2, the data in the row of space corresponding to the target coding gradient is updated.

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

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

[0103] The execution process of step S124 is similar to that of step S122a, and will not be described again for simplicity. Steps S123 to S125 are executed after step S122a. Over time, due to the relaxation phenomenon of hydrogen atoms, the intensity of the signals generated by various tissues in the imaging region will gradually increase towards 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 signals of various tissues have largely recovered to their initial signal intensities. Therefore, the images obtained through steps S123 and S124 can be considered as the background image of blood vessels in the imaging region.

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

[0105] Magnetic resonance imaging (MRI) images can be superimposed and fused with a background image using preset coefficients. It should be understood that before fusion, one or both of the MRI and background images can be processed using image processing operations. For example, these image processing operations may include image enhancement, brightness adjustment, filtering, and image segmentation. In one example, maximum projection processing can be performed on the MRI image to primarily display blood vessels. In other examples, minimum projection, 3D segmentation reconstruction, etc., can also be used to process the MRI image and / or the background image. It is understood that an MRI image sequence may also include multiple fused images.

[0106] According to the above-described scheme of the present invention, for each target encoding gradient, the data in the corresponding space in the K-space can be updated. Then, the updated data is subjected to inverse Fourier transform processing to obtain a background image. Finally, the magnetic resonance image and the background image are fused to obtain a fused image. In the above scheme, the magnetic resonance image mainly provides blood flow information, and the background image mainly provides background information. Therefore, the obtained fused image can provide richer information for user analysis, which is beneficial for qualitative research on the target object.

[0107] For example, the generation of the magnetic resonance image based on the acquired magnetic resonance signal in step S120 may include steps S121b and S122b.

[0108] In step S121b, the K-space is filled with data based on the acquired magnetic resonance signal.

[0109] This invention does not limit the specific method of data filling in the K-space; the method can be determined according to the actual needs of the developers or users. In one example, the aforementioned 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 using a spatiotemporal joint reconstruction algorithm.

[0111] Spatiotemporal joint reconstruction (SLTRC) algorithms can rapidly generate magnetic resonance images by undersampling data in the K-space. Examples of SLTRC algorithms include compressed sensing-based algorithms, low-rank matrix / tensor decomposition-based algorithms, deep learning-based algorithms, and algorithms based on the golden flip angle. In one example, SLTRC algorithms can also generate additional magnetic resonance images based on pre-filled K-space data obtained at different times (e.g., data in the K-space used to generate different magnetic resonance images). This increases the total number of magnetic resonance images in a sequence, improving the visual smoothness of the sequence.

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

[0113] According to the above-described scheme of the present invention, data filling can be performed on the K-space based on the acquired magnetic resonance signal. Then, based on the data in the filled K-space, a magnetic resonance image is generated through a spatiotemporal joint reconstruction algorithm. The above scheme can utilize the spatiotemporal joint reconstruction algorithm to quickly generate magnetic resonance images, which is beneficial to improving the generation efficiency of magnetic resonance images.

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

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

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

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

[0118] For example, processor 210 is configured to control execution device 220 to perform the following steps: when N is a positive odd number, after the layer-selection saturation pulse signal saturates the tissue in at least the imaging region, and before the first inversion pulse signal among N inversion pulse signals performs a first inversion operation on the 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 the blood in the marking region.

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

[0120] For example, the first pulse signal is generated at the end of the generation of the (i+1)th inverted pulse signal from the end, and continues until the start of the generation of the ith inverted pulse signal from the end.

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

[0122] For example, the length of the marked region along the flow direction of the blood to be imaged is greater than or equal to the first product, and the difference between the marked region and the first product is less than the difference threshold, wherein the first product is the product of the time interval between the (i+1)th inverted pulse signal and the i-th inverted pulse signal and the blood flow velocity of the blood to be imaged.

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

[0124] For example, processor 210 is configured to control execution device 220 to sequentially generate a layer-selected saturation pulse signal and N inverted pulse signals in at least the imaging region of the target object, and is further configured to sequentially generate a layer-selected saturation pulse signal and N inverted pulse signals in a background suppression region of the target object. The background suppression region includes the imaging region. The background suppression region and the imaging region have the same edges adjacent to the marked region, and the length of the background suppression region is greater than or equal to the maximum value in the second product in the flow direction of the blood to be imaged. The second product includes the product of the time interval between every two adjacent target pulse signals and the blood flow velocity of the blood to be suppressed. The target pulse signal includes a layer-selected saturation pulse signal and N inverted pulse signals.

[0125] For example, processor 210 is configured to control execution device 220 to acquire magnetic resonance signals of tissue in the imaging region, and processor 210 is configured to generate the magnetic resonance image based on the acquired magnetic resonance signals. Further configured, execution device 220 acquires magnetic resonance signals of tissue in the imaging region based on a center-priority sampling mode in K-space. Processor 210 is configured to fill 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.

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

[0127] Processor 210 is configured to perform an inverse Fourier transform on the updated data to obtain a background image. The magnetic resonance image is then fused with the background image to obtain a fused image.

[0128] For example, the processor 210 generates the magnetic resonance image based on the acquired magnetic resonance signal, and is further configured to: fill the K-space with data based on the acquired magnetic resonance signal. Based on the data in the filled K-space, the magnetic resonance image is generated through a spatiotemporal joint reconstruction algorithm.

[0129] Furthermore, according to another aspect of the present invention, a non-volatile storage medium is provided, on which program instructions are stored. When the program instructions are executed by a computer or processor, the computer or processor performs corresponding steps of the magnetic resonance angiography method described in the embodiments of the present invention, and is used to implement corresponding modules in the magnetic resonance imaging device described in the embodiments of the present invention. The non-volatile storage medium may, for example, include a memory card of a smartphone, a storage component of a tablet computer, a hard disk of a personal computer, 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 non-volatile storage media. The non-volatile 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 also provided, including computer program instructions. When the computer program instructions are executed by a computer or processor, the computer or processor performs corresponding steps of the magnetic resonance angiography method described above.

[0130] Those skilled in the art can understand the specific implementation scheme of the above-mentioned magnetic resonance imaging device and non-volatile storage medium by reading the relevant description of the magnetic resonance angiography method. For the sake of brevity, it will not be described in detail here.

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

[0132] Those skilled in the art will recognize that the units and algorithm steps of the various examples 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 implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0133] In the several embodiments provided by this 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 instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0134] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

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

[0136] Those skilled in the art will understand that, apart from the mutual exclusion of features, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or elements of any method or apparatus so disclosed may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

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

[0138] The various component embodiments of the present invention can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some modules in the magnetic resonance imaging apparatus according to embodiments of the present invention. The present invention can also be implemented as an apparatus program (e.g., a computer program and computer program product) for performing some or all of the methods described herein. Such programs implementing the present invention can be stored on a computer-readable medium or can be in the form of one or more signals. Such signals can 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 are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses 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 invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims 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 can be interpreted as names.

[0140] The above description is merely a specific embodiment of the present invention or an explanation of that embodiment. The scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A magnetic resonance angiography method, characterized in that, The method includes: 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 the imaging area of ​​the target object, a layer-selected saturation pulse signal and N inversion pulse signals are generated sequentially. The preset time period corresponding to the magnetic resonance image includes a period from a first moment to a second moment. The first moment is the start moment for generating the layer-selected saturation pulse signal used to generate the magnetic resonance image, and the second moment is the start moment for signal acquisition of the magnetic resonance image. The N inversion pulse signals are used to perform a first inversion operation on the tissue in at least the imaging area. After or simultaneously with performing the first inversion operation on the tissue in at least the imaging area using the (i+1)th inverse inversion pulse signal among the N inversion pulse signals, and before performing the first inversion operation on the tissue in at least the imaging area using the i-th inverse inversion pulse signal among the N inversion pulse signals, a second inversion operation is performed on the blood in the marked area of ​​the target object, so that the longitudinal magnetization direction of the blood after the second inversion operation is positive when it is imaged in the imaging area. N is a non-negative integer, and i is a positive odd number less than or equal to N-1. The marked area is adjacent to the imaging area, and the blood to be imaged flows into the imaging area through the marked area. 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; 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.

2. The method as described in claim 1, characterized in that, The method further includes: When N is a positive odd number, after the layer-selected saturation pulse signal saturates the tissue in at least the imaging region, and before the first inversion pulse signal of the N inversion pulse signals performs a first inversion operation on the tissue in at least the imaging region, another inversion pulse signal is generated in the marked region, wherein the other inversion pulse signal is used to perform a second inversion operation on the blood in the marked region.

3. The method as described in claim 1, characterized in that, The second inversion operation on the blood in the marked area of ​​the target object includes: An additional inversion pulse signal is generated in the marked area of ​​the target object, wherein the additional inversion pulse signal is used to perform a second inversion operation on the blood in the marked area.

4. The method as described in claim 3, characterized in that, The additional inverted pulse signal is generated at the end of the generation of the (i+1)th inverted pulse signal from the end, and continues until the start of the generation of the ith inverted pulse signal from the end.

5. The method as described in claim 1, characterized in that, The 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 marked region 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 region and the marked region.

6. The method as described in claim 5, characterized in that, The length of the marked region along the flow direction of the blood to be imaged is greater than or equal to the first product, and the difference between the marked region and the first product is less than the difference threshold, wherein the first product is the product of the time interval between the (i+1)th inverted pulse signal and the i-th inverted pulse signal and the blood flow velocity of the blood to be imaged.

7. The method as described in claim 1, characterized in that, The value of N is determined based on the duration of a preset time period corresponding to the magnetic resonance image.

8. The method as described in claim 1, characterized in that, In at least the imaging region of the target object, a layer-selected saturation pulse signal and N inverted pulse signals are generated sequentially, including: Layer-selected saturated pulse signals and N inverted pulse signals are sequentially generated in the background suppression region of the target object. The background suppression region includes the imaging region. The background suppression region and the imaging region have the same edge adjacent to the marked region. In the direction of blood flow to be imaged, the length of the background suppression region is greater than or equal to the maximum value in the second product. The second product includes the product of the time interval between every two adjacent target pulse signals and the blood flow velocity of the blood to be suppressed. The target pulse signals include the layer-selected saturated pulse signals and the N inverted pulse signals.

9. The method as described in claim 1, characterized in that, The process of acquiring magnetic resonance signals from tissues in the imaging region and generating a magnetic resonance image based on the acquired magnetic resonance signals includes: Based on the center-priority sampling mode of K-space, magnetic resonance signals of tissue are acquired in the imaging region, and the K-space is filled with data based on the acquired magnetic resonance signals. The magnetic resonance image is generated based on the data in the filled K-space.

10. The method as described in claim 9, characterized in that, The method of acquiring 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 coding gradient, the following steps are performed until the data in each row of space corresponding to each target coding gradient in the filled K-space is updated to obtain the updated data, wherein the target coding gradient is the phase coding gradient corresponding to the central region in the K-space: Based on the target encoding gradient, magnetic resonance signals are acquired in the imaging region; Update the data in one row space corresponding to the target encoding gradient; The updated data is then subjected to an inverse Fourier transform to obtain the 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, The process of generating the magnetic resonance image based on the acquired magnetic resonance signal includes: Based on the acquired magnetic resonance signals, data is filled into the K-space; The magnetic resonance image is generated based on the data in the filled K-space using a spatiotemporal joint reconstruction algorithm.

12. A magnetic resonance imaging device, characterized in that, The device includes a processor and an execution device, wherein, for each magnetic resonance image to be generated in a sequence of magnetic resonance images, 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 the imaging area of ​​the target object, a layer-selected saturation pulse signal and N inversion pulse signals are generated sequentially. The preset time period corresponding to the magnetic resonance image includes a period from a first moment to a second moment. The first moment is the start moment for generating the layer-selected saturation pulse signal used to generate the magnetic resonance image, and the second moment is the start moment for signal acquisition of the magnetic resonance image. The N inversion pulse signals are used to perform a first inversion operation on the tissue in at least the imaging area. After or simultaneously with performing the first inversion operation on the tissue in at least the imaging area using the (i+1)th inverse inversion pulse signal among the N inversion pulse signals, and before performing the first inversion operation on the tissue in at least the imaging area using the i-th inverse inversion pulse signal among the N inversion pulse signals, a second inversion operation is performed on the blood in the marked area of ​​the target object, so that the longitudinal magnetization direction of the blood after the second inversion operation is positive when it is imaged in the imaging area. N is a non-negative integer, and i is a positive odd number less than N. The marked area is adjacent to the imaging area, and the blood to be imaged flows into the imaging area through the marked area. Acquire magnetic resonance signals from the tissue in the imaging region; The processor is also 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.

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

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

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