Magnetic resonance blood imaging method, device and non-transitory storage medium

Abstract

The application provides a magnetic resonance blood imaging method, device and nonvolatile storage medium. The method comprises: generating a layer selection saturation pulse signal in an imaging region; sequentially generating N inversion pulse signals in the imaging region to perform a first inversion operation on tissues in the imaging region; after or simultaneously with performing the first inversion operation on the tissues in the imaging region by using an (N-i+1)th inversion pulse signal in the N inversion pulse signals, and before performing the first inversion operation on the tissues in the imaging region by using an (N-i)th inversion pulse signal in the N inversion pulse signals, performing a second inversion operation on blood in a labeling region, i being a positive odd number smaller than N; collecting a magnetic resonance signal of the tissues in the imaging region, and generating a magnetic resonance image. The total imaging time is shorter, and the generation efficiency of the magnetic resonance image is improved. Moreover, the influence of the pose of a target object on the contrast of the magnetic resonance image is reduced.

Description

Technical Field

[0001] This invention relates to the field of medical imaging technology, and more specifically to a magnetic resonance blood imaging method, a magnetic resonance blood 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 body's internal structures. Unlike X-ray or CT scans, MRI does not use ionizing radiation, making it safer for the subject. However, current MRI technology has several limitations, particularly in applications requiring high-contrast images and rapid imaging.

[0003] To improve the visibility of blood in certain areas of an imaging subject, traditional 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. Other approaches utilize subtraction techniques to generate MRI images. Subtraction requires acquiring at least two MRI images and then subtracting them to visualize the blood. Therefore, this imaging process is time-consuming and inefficient. On the one hand, this significantly impacts the patient's experience. On the other hand, it is difficult for the subject to maintain a stable posture during the long imaging process. Changes in posture lead to poor contrast in the subtraction-generated MRI image. Summary of the Invention

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

[0005] According to one aspect of the present invention, a magnetic resonance blood imaging method is provided, the method comprising: generating a layer-selected saturation pulse signal in an imaging region of at least a target object; sequentially generating N inversion pulse signals in the imaging region to perform a first inversion operation on tissue in the imaging region, wherein, after or simultaneously with performing the first inversion operation on tissue in the imaging region using the (i+1)th inverse of the N inversion pulse signals, and before performing the first inversion operation on tissue in the imaging region using the i-th inverse of the N inversion pulse signals, a second inversion operation is performed on blood in a marker region of the target object, i being a positive odd number less than N, the marker region being adjacent to the imaging region and the blood to be imaged flowing into the imaging region through the marker region; acquiring magnetic resonance signals of tissue in the imaging region, and generating a magnetic resonance image based on the acquired magnetic resonance signals.

[0006] For example, performing a second inversion operation on blood in a marked region of a target object includes:

[0007] Only between the end of the generation of the (i+1)th inverted pulse signal and the start of the generation of the ith inverted pulse signal, another inverted pulse signal is generated in the marked area of ​​the target object to perform a second inverted operation on the blood in the marked area.

[0008] For example, the additional inverted pulse signal is generated at the end of the generation of the (i+1)th inverted pulse signal and continues until the start of the generation of the ith inverted pulse signal.

[0009] For example, another inverted pulse signal is an arterial spin labeling pulse signal, wherein the arterial spin labeling pulse signal is used to label the blood in the labeling region with arterial spin.

[0010] For example, arterial spin labeling includes any one of the following: continuous arterial spin labeling and pseudo-continuous arterial spin labeling.

[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 equal to a first value, wherein the first value is the product of the time interval between the (i+1)th inverted pulse signal and the i-th inverted pulse signal from the end and the blood flow velocity of the blood to be imaged.

[0014] For example, generating a layer-selective saturation pulse signal in at least the imaging region of the target object includes:

[0015] A layer-selected saturated pulse signal is generated in the background suppression region of the target object, wherein the background suppression region includes the imaging region, the background suppression region and the imaging region have the same edge adjacent to the marker region, and the length of the background suppression region is greater than or equal to the maximum value in the second value in the direction of blood flow to be imaged, the second value 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, and the target pulse signal includes a layer-selected saturated pulse signal and N inverted pulse signals;

[0016] N inversion pulse signals are sequentially generated in at least the imaging region to perform a first inversion operation on the tissue in at least the imaging region, including:

[0017] N inversion pulse signals are generated sequentially in the background suppression region to perform the first inversion operation on the tissue in the background suppression region.

[0018] 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:

[0019] 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;

[0020] The data in the filled K-space are then subjected to inverse Fourier transform to obtain the magnetic resonance image.

[0021] For example, acquiring magnetic resonance signals of tissue in the imaging region and generating a magnetic resonance image based on the acquired magnetic resonance signals further includes:

[0022] 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. Here, the target coding gradient is the phase coding gradient corresponding to the preset region in the K-space:

[0023] Based on the target encoding gradient, magnetic resonance signals are acquired in the imaging region;

[0024] Update the data in one row space corresponding to the target encoding gradient;

[0025] The updated data is then subjected to an inverse Fourier transform to obtain the background image.

[0026] The magnetic resonance image is fused with the background image to obtain a fused image.

[0027] For example, the preset area is the central area in the K space.

[0028] According to another aspect of the present invention, a magnetic resonance blood imaging device is provided, the magnetic resonance blood imaging device comprising a processor and an execution device, the processor being configured to control the execution device to perform the following steps:

[0029] Generate a layer-selected saturation pulse signal in at least the imaging region of the target object;

[0030] N inversion pulse signals are generated sequentially in at least the imaging region 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. 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.

[0031] The magnetic resonance signals of the tissue in the imaging area are acquired, and a magnetic resonance image is generated based on the acquired magnetic resonance signals.

[0032] According to another aspect of the present invention, a non-volatile storage medium is also provided. Computer program instructions are stored on this non-volatile storage medium, which, when executed, are used to perform the aforementioned magnetic resonance blood imaging method.

[0033] 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, perform the aforementioned magnetic resonance blood imaging method.

[0034] In embodiments of the present invention, on one hand, by applying a layer-selected saturation pulse signal and an inversion pulse signal to at least the imaging region, background signals in the imaging region are suppressed. This improves the contrast of the magnetic resonance image. On the other hand, a second inversion operation is performed on the blood in the marked region, thus enhancing the imaging contrast of the blood to be imaged in the imaging region. Since no subtraction technique is needed to generate the magnetic resonance image, the overall magnetic resonance imaging process in this embodiment is shorter, significantly improving imaging efficiency. Finally, this helps to reduce the influence of the target object's pose on the contrast of the magnetic resonance image. Attached Figure Description

[0035] 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.

[0036] Figure 1 A schematic flowchart of a magnetic resonance blood imaging method according to an embodiment of the present invention is shown;

[0037] Figure 2 A schematic diagram of a magnetic resonance blood imaging method according to an embodiment of the present invention is shown;

[0038] Figure 3 A simulation graph showing the signal strength of an tissue over time according to an embodiment of the present invention is shown;

[0039] Figure 4 A schematic diagram of a magnetic resonance image of the head according to an embodiment of the present invention is shown;

[0040] Figure 5 A schematic diagram of a magnetic resonance image of a kidney is shown according to an embodiment of the present invention;

[0041] Figure 6 A simulation diagram showing the change of signal intensity of arterial blood over time according to an embodiment of the present invention is shown;

[0042] Figure 7 A simulation diagram showing the change in signal intensity of arterial blood over time according to an embodiment of the present invention is shown; and

[0043] Figure 8 A schematic block diagram of a magnetic resonance blood imaging apparatus according to an embodiment of the present invention is shown. Detailed Implementation

[0044] 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.

[0045] To at least partially solve the above problems, embodiments of the present invention provide a magnetic resonance blood imaging method. Figure 1A schematic flowchart of a magnetic resonance blood imaging method according to an embodiment of the present invention is shown. Figure 1 As shown, the method may include the following steps S110 to S130.

[0046] In step S110, a layer-selected saturation pulse signal is generated in at least the imaging region of the target object.

[0047] For example, a magnetic resonance imaging (MRI) system can be used to acquire magnetic resonance signals for a target object. The MRI system 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 into 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, from a macroscopic perspective, can be considered 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, which, from a macroscopic perspective, 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.

[0048] 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 should be 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.

[0049] The aforementioned layer-selective 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 increase, and with the precession of hydrogen atoms, a time-varying magnetic resonance signal is generated. The Y-axis can be the vertical axis. For example, if the signal intensity of the unprocessed magnetic resonance signal corresponding to arterial blood (hereinafter referred to as the signal) is taken as 1, and the signal intensity after applying the inverted pulse signal to the arterial blood is taken as -1, then ideally, the layer-selective saturation pulse signal can adjust the signal intensity of the signal generated by the tissue in the application area to 0. It is understood that the tissue in the application area can include solid tissues, such as fat and brain tissue, and can also include fluid tissues, such as blood and cerebrospinal fluid. Therefore, through this layer-selective saturation pulse signal, background signal suppression, such as fat suppression and fluid suppression such as cerebrospinal fluid, can be achieved. It should be understood that the aforementioned layer-selection saturation pulse signal may include a single pulse or multiple pulses.

[0050] In one example, a layer-selective saturation pulse signal may be generated only within the imaging region. In another example, a layer-selective saturation pulse signal may 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, and can also suppress venous blood flowing in the opposite direction of arterial blood flow. Furthermore, it can ensure that the signal is adequately suppressed even if the tissue is located at the edge of the imaging region, 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 as the background suppression region of the target object below.

[0051] In step S120, N inversion pulse signals are sequentially generated in at least the imaging region to perform a first inversion operation on the tissue in at least the imaging region.

[0052] 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 in the region where the inversion pulse signal is applied. 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 to selectively suppress background tissue signals, such as adipose tissue. It should be 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 pulses may be the same.

[0053] 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.

[0054] The aforementioned N can be a preset positive integer value, used to represent the total number of inversion pulse signals for the first inversion operation. The specific value can be determined by the developers based on actual conditions. It should be understood that in related technologies, the inversion recovery time can be related to the magnitude of N, blood transit time (BTT), etc. The aforementioned inversion recovery time can be used to represent the optimal time for image acquisition.

[0055] It should be understood that the values ​​mentioned in the embodiments of this application are all values ​​under ideal conditions, and the values ​​under actual conditions may deviate.

[0056] In one example, N could be 4. See also Figure 2 , Figure 2 A schematic diagram of a magnetic resonance blood imaging method according to an embodiment of the present invention is shown. (Combined with...) Figure 2If the inverted pulse signals are arranged in reverse chronological order, then the N inverted pulse signals can include inverted pulse signals 1 to 4. 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. It should be understood that the time interval from the generation start time of the layer-selected saturation pulse signal to time 0 can be set according to the actual needs of the developers, and this embodiment of the application does not impose any limitations. For example, for older individuals, this time interval can be set to be longer, while for younger individuals it can be set to be shorter.

[0057] In one example, after performing a first inversion operation on the tissue in the background suppression region or 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 the background suppression region or imaging region using the ith inversion pulse signal out of N inversion pulse signals, a second inversion operation is performed on the blood in the marked region of the target object. 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. It should be understood that the blood to be imaged can be arterial blood or venous blood.

[0058] For example, if there are a total of 4 inversion pulse signals, a second inversion operation can be performed on the blood in the marked area of ​​the target object after the first inversion operation is performed on the tissue in the background suppression region or imaging region using the second-to-last inversion pulse signal (e.g., inversion pulse signal 2 mentioned above) and before the first inversion operation is performed on the tissue in the background suppression region or imaging region using the penultimate inversion pulse signal (e.g., inversion pulse signal 1 mentioned above).

[0059] An additional inversion pulse signal can be generated in the marked region to perform a second inversion operation on the blood in the marked region. The inversion pulse signal acting on the marked region can have the same target parameters (e.g., pulse frequency, pulse duration, etc.) as the inversion pulse signal acting on the background suppression region.

[0060] The marked area can be adjacent to the imaging area. For example, Figure 2 The image shows an example where the imaging area is a portion of a target's brain region. In this example, the blood being 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 described above. Figure 2The example also illustrates 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 area.

[0061] In another example, while 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 is performed on the blood in the marked region of the target object.

[0062] As previously mentioned, layer-selective saturation pulse signals can adjust the signal intensity of the signal generated by tissue in the background suppression region to 0. Over time, due to the relaxation phenomenon of hydrogen atoms, the signal intensity gradually increases towards 1. At time 0, after N inversion pulse signals have been applied and the magnetic resonance signal is acquired, the signal intensity can approach 0. (See also...) Figure 3 , Figure 3 A simulation graph showing the signal strength of an tissue over time according to an embodiment of the present invention is shown. Figure 3 In this example, the tissue may specifically include cerebrospinal fluid (CSF), gray matter (GM), white matter (WM), and fat. In this example, N is 4, and a layer-selected saturation pulse signal can be applied to the background suppression region at -2000 ms to adjust the signal intensity of the signal generated by the tissue in the background suppression region at -2000 ms to 0. The blood in the background suppression region may include arterial blood and venous blood. Venous blood has a slower flow rate, so most of the hydrogen atoms in the venous blood will remain in the background suppression region at time 0. The signal intensity of the signal generated by the hydrogen atoms remaining in the background suppression region (hereinafter referred to as the first intensity) can be adjusted by applying N inverted pulse signals. It should be understood that the hydrogen atoms remaining in the background suppression region may also include hydrogen atoms from the tissue in the background suppression region. Specifically, between -2000 ms and -1652.1 ms, due to the relaxation phenomenon of hydrogen atoms, the first intensity will gradually increase towards 1, for example... Figure 3 The signal intensity of the cerebrospinal fluid (CSF) increases to 0.7. After the first inversion pulse signal performs the first inversion operation on the tissue in the background suppression region, the direction of the net magnetization vector of the CSF will reverse 180 degrees, adjusting the first intensity of the CSF to -0.7. Through the action of N inversion pulse signals, the first intensity of the CSF can be made close to 0 at time 0, thus achieving background suppression of the CSF. For example... Figure 3 The signal intensity of the gray matter increases from 0 to 0.35 between -2000 ms and -1652.1 ms. Therefore, after the first inversion pulse signal performs the first inversion operation on the tissue in the background suppression region, the direction of the net magnetization vector of the gray matter is reversed by 180 degrees, adjusting the first intensity of the gray matter to -0.35. Through the action of N inversion pulse signals, the first intensity of the gray matter can be made close to 0 at time 0, thus achieving background suppression for the gray matter. Background suppression for other tissues is similar and will not be elaborated here.

[0063] In this embodiment of the invention, blood samples undergoing an even number of inversion pulse signals in the imaging region are represented as positive signals during imaging. A second inversion operation is performed on the blood in the marked region before or simultaneously with the first inversion operation on the tissue in the background suppression region using the (i+1)th inversion pulse signal from the end. Here, i is a positive odd number. The second inversion operation is used to pre-invert a portion of the blood sample before it flows into the imaging region. Thus, for blood samples undergoing an odd number of inversion pulse signals in the imaging region, the combined effect of the second and first inversion operations also results in a positive signal during imaging.

[0064] According to embodiments of the present invention, the available blood inflow time is extended, and the range of selectable reversal recovery times is wider. This facilitates the decoupling of blood inflow time and reversal recovery time, improving scenario adaptability.

[0065] In step S130, magnetic resonance signals of the tissue in the imaging area are acquired, and a magnetic resonance image is generated based on the acquired magnetic resonance signals.

[0066] After steps S110 and S120, magnetic resonance signals of the tissue in the imaging region can be acquired at time 0. In some examples, multiple preset phase-encoded gradients can be sequentially used in at least the imaging region via 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 fill the row corresponding to that phase gradient encoding in K-space. After each row is filled, 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 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 should be 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.

[0067] In some embodiments, imaging techniques from related technologies can also 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.

[0068] In one example, the magnetic resonance image can be processed and displayed using image processing algorithms from related technologies. For instance, feature enhancement and noise suppression can be performed on the magnetic resonance image. As another example, region segmentation algorithms or models from related technologies can be used to determine the region of interest in the magnetic resonance image.

[0069] See Figure 4 and Figure 5 , Figure 4 A schematic diagram of a magnetic resonance imaging (MRI) image of the head according to an embodiment of the present invention is shown. Figure 5 A schematic diagram of a magnetic resonance imaging (MRI) image of a kidney according to an embodiment of the present invention is shown. Figure 4 and Figure 5 In magnetic resonance imaging, pixels with larger pixel values ​​correspond to the blood being imaged, indicating that the blood being imaged has higher imaging contrast, which is helpful for users to conduct qualitative studies on the brain or kidneys of the target object.

[0070] According to the above-described solution provided by the embodiments of the present invention, on the one hand, by applying a layer-selected saturation pulse signal and an inversion pulse signal to at least the imaging region, the background signal in the imaging region is suppressed. This improves the contrast of the magnetic resonance image. On the other hand, a second inversion operation is performed on the blood in the marked region, thus enhancing the imaging contrast of the blood to be imaged in the imaging region. Since no subtraction technique is needed to generate the magnetic resonance image, the total time consumed by the magnetic resonance imaging process in the embodiments of this application is shorter, significantly improving imaging efficiency. Finally, this helps to reduce the influence of the pose of the target object on the contrast of the magnetic resonance image.

[0071] For example, the second inversion operation on the blood in the marked area of ​​the target object described above may include: generating an additional inversion pulse signal in the marked area of ​​the target object only between the end time of the generation of the (i+1)th inversion pulse signal and the start time of the generation of the i-th inversion pulse signal, so as to perform the second inversion operation on the blood in the marked area.

[0072] From a macroscopic perspective, the aforementioned additional reversal pulse signal can be used to implement the second reversal operation. The second reversal operation can be to reverse the direction of the net magnetization vector formed by the tissue in the marked region. For example, the second reversal operation can reverse the direction of the net magnetization vector by 180 degrees. In one example, the target parameters of the aforementioned additional reversal pulse signal can be the same as the target parameters of the reversal pulse signal used to implement the first reversal operation in step S120. In yet another example, pulse signals with different pulse types that can reverse the direction of the net magnetization vector can also be used. The aforementioned additional reversal pulse signal can include a single pulse or multiple pulses; this embodiment of the invention does not impose any limitations.

[0073] exist Figure 2In the illustrated embodiment, between the time of generating inverted pulse signal 1 (i.e., -107 ms) and the time of generating inverted pulse signal 2 (i.e., -435.8 ms), an additional inverted pulse signal is generated for performing the second inversion operation. Between the time of generating inverted pulse signal 3 (i.e., -987.7 ms) and the time of generating inverted pulse signal 4 (i.e., -1652.1 ms), an additional inverted pulse signal is also generated for performing the second inversion operation. Arterial blood flowing into the imaging region during the period from time 0 to time -107 ms does not experience any inverted pulse signals. Arterial blood flowing into the imaging region during the period from time -435.8 ms to time -987.7 ms and before time -1652.1 ms has experienced an even number of inverted pulse signals applied to the background suppression region by 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 another inversion 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 another inversion 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.

[0074] See Figure 6 and Figure 7 , Figure 6 A simulation graph showing the change of arterial blood signal intensity over time according to an embodiment of the present invention is shown. Figure 7 A simulation diagram showing the change in signal intensity of arterial blood over time according to an embodiment of the present invention is shown.

[0075] Combination Figure 6 and Figure 7If the inflow time of arterial blood (which in this embodiment can be considered as the blood to be imaged) is between -435.8 and -107 milliseconds (in other words, the arterial blood flows into the imaging area between -435.8 and -107 milliseconds), then the arterial blood is located in the marked area before the generation start time of the inversion pulse signal 1. The initial signal strength of the arterial blood signal (hereinafter referred to as the second strength) is 1. A further inversion pulse signal can perform a second inversion operation on the blood in the marked area to adjust the second strength to -1. At the generation start time of the inversion pulse signal 1, the arterial blood has already flowed into the imaging area, and due to the relaxation phenomenon of hydrogen atoms, the second strength will gradually increase towards 1. Figure 6 Taking arterial blood with an inflow time of -210 milliseconds as an example, the second intensity of this arterial blood can be increased to -0.9. In this example, the inversion pulse signal 1 performs a first inversion operation on the tissue in the imaging region, which may include performing a first inversion operation on the aforementioned arterial blood flowing into the imaging region to adjust the second intensity to 0.9. Due to the relaxation phenomenon of hydrogen atoms, the second intensity will gradually increase towards 1. At time 0, the second intensity is approximately 0.95.

[0076] If the arterial blood inflow time is between -987.7 and -435.8 milliseconds (in other words, the arterial blood flows into the imaging area between -987.7 and -435.8 milliseconds), then the arterial blood is located in the marked area before the generation start time of the inversion pulse signal 2. The initial signal strength of the arterial blood signal (hereinafter referred to as the third strength) is 1. There is no other inversion pulse signal between inversion pulse signal 3 and inversion pulse signal 2, so the third strength remains almost unchanged between the generation end time of inversion pulse signal 3 and the generation start time of inversion pulse signal 2. At the generation start time of inversion pulse signal 2, the arterial blood has already flowed into the imaging area. The inversion pulse signal 2 performs a first inversion operation on the tissue in the imaging area, which may include: performing a first inversion operation on the aforementioned arterial blood flowing into the imaging area to adjust the third strength to -1. Due to the relaxation phenomenon of hydrogen atoms, the third strength will gradually increase towards 1. Here, it is used as... Figure 6 Taking arterial blood with an inflow time of -540 milliseconds as an example, the third intensity of this arterial blood can be increased to -0.6. The inversion pulse signal 1 performs a first inversion operation on the tissue in the imaging region, which may include performing a first inversion operation on the aforementioned arterial blood flowing into the imaging region to adjust the third intensity to 0.6. Due to the relaxation phenomenon of hydrogen atoms, the third intensity gradually increases towards 1, and at time 0, the third intensity is approximately 0.65.

[0077] If the arterial blood inflow time is between -1652.1 and -987.7 milliseconds (in other words, the arterial blood flows into the imaging area between -1652.1 and -987.7 milliseconds), then the arterial blood is located in the marked area before the generation start time of inversion pulse signal 3. The initial signal strength of the arterial blood signal (hereinafter referred to as the fourth strength) is 1. Another inversion pulse signal is generated between the generation end time of inversion pulse signal 4 and the generation start time of inversion pulse signal 3. This additional inversion pulse signal can perform a second inversion operation on the blood in the marked area to adjust the fourth strength to -1. At the generation start time of inversion pulse signal 3, the arterial blood has already flowed into the imaging area, and due to the relaxation phenomenon of hydrogen atoms, the fourth strength will gradually increase towards 1. Here, we use... Figure 6 Taking arterial blood with an inflow time of -1090 milliseconds as an example, the fourth intensity of this arterial blood can be increased to -0.8. In this example, the inversion pulse signal 3 performs a first inversion operation on the tissue in the imaging region, which may include performing a first inversion operation on the aforementioned arterial blood flowing into the imaging region to adjust the fourth intensity to 0.8. Due to the relaxation phenomenon of hydrogen atoms, the fourth intensity will gradually increase towards 1, for example, increasing to 0.9. The inversion pulse signal 2 performs a first inversion operation on the tissue in the imaging region, which may include performing a first inversion operation on the aforementioned arterial blood flowing into the imaging region to adjust the fourth intensity to -0.9. Due to the relaxation phenomenon of hydrogen atoms, the fourth intensity will gradually increase towards 1, increasing to -0.5 in this example. The inversion pulse signal 1 performs a first inversion operation on the tissue in the imaging region, which may include performing a first inversion operation on the aforementioned arterial blood flowing into the imaging region to adjust the fourth intensity to 0.5. Due to the relaxation phenomenon of hydrogen atoms, the fourth intensity will gradually increase towards 1, and at time 0, the fourth intensity is approximately 0.55.

[0078] If the arterial blood inflow time is between -2000 and -1652.1 milliseconds (in other words, the arterial blood flows into the imaging area between -2000 and -1652.1 milliseconds), then the arterial blood is located in the marked area before the generation start time of the inversion pulse signal 1. The initial signal strength of the arterial blood signal (hereinafter referred to as the fifth strength) is 1. At the generation start time of the inversion pulse signal 4, the arterial blood has flowed into the imaging area. The inversion pulse signal 4 performs a first inversion operation on the tissue in the imaging area, which may include: performing a first inversion operation on the aforementioned arterial blood flowing into the imaging area to adjust the fifth strength to -1. Due to the relaxation phenomenon of hydrogen atoms, the fifth strength will gradually increase towards 1. Here, it is used as... Figure 6Taking arterial blood with an inflow time of -1750 milliseconds as an example, the fourth intensity of this arterial blood can be increased to -0.25. The inversion pulse signal 3 performs a first inversion operation on the tissue in the imaging region, which may include performing a first inversion operation on the aforementioned arterial blood flowing into the imaging region to adjust the fifth intensity to 0.25. Due to the relaxation phenomenon of hydrogen atoms, the fifth intensity will gradually increase towards 1, for example, increasing to 0.5. The inversion pulse signal 2 performs a first inversion operation on the tissue in the imaging region, which may include performing a first inversion operation on the aforementioned arterial blood flowing into the imaging region to adjust the fifth intensity to -0.5. Due to the relaxation phenomenon of hydrogen atoms, the fifth intensity will gradually increase towards 1, increasing to -0.2 in this example. The inversion pulse signal 1 performs a first inversion operation on the tissue in the imaging region, which may include performing a first inversion operation on the aforementioned arterial blood flowing into the imaging region to adjust the fifth intensity to 0.2. Due to the relaxation phenomenon of hydrogen atoms, the fifth intensity will gradually increase towards 1, and at time 0, the fifth intensity is approximately 0.25.

[0079] According to the above-described scheme of the present invention, an additional inversion pulse signal can be generated in the marked region of the target object only between the end time of the generation of the (i+1)th inversion pulse signal from the end and the start time of the generation of the ith inversion pulse signal from the end, to perform a second inversion operation on the blood in the marked region. In the above scheme, the time interval between the inversion pulse signal used to perform the second inversion operation and the inversion pulse signal used to perform the adjacent first inversion operation is shorter, thus more effectively performing the second inversion operation on the blood about to flow into the imaging region. This ensures the contrast of the blood in the magnetic resonance image.

[0080] For example, an additional inverted pulse signal may be generated at the end of the generation of the (i+1)th inverted pulse signal and continue until the start of the generation of the ith inverted pulse signal.

[0081] In this example, the duration of the additional inverted pulse signal can be greater than the duration of any single inverted pulse signal among the N inverted pulse signals. The duration of any single inverted pulse signal among the additional inverted pulse signals can also be different.

[0082] Referring back to the example of N=4 above, another inverted pulse signal can be generated in the marked area between the end time of inverted pulse signal 2 and the start time of inverted pulse signal 1. The duration of this inverted pulse signal can be a first duration. This first duration can be equal to the absolute value obtained by subtracting the start time of inverted pulse signal 1 from the end time of inverted pulse signal 2. Similarly, another inverted pulse signal can be generated in the marked area between the end time of inverted pulse signal 4 and the start time of inverted pulse signal 3. The duration of this inverted pulse signal can be a second duration. This second duration can be equal to the absolute value obtained by subtracting the start time of inverted pulse signal 3 from the end time of inverted pulse signal 4.

[0083] According to the above-described scheme of the present invention, the additional inversion pulse signal can be generated at the end of the generation of the (i+1)th inversion pulse signal from the end and continue until the start of the generation of the ith inversion pulse signal from the end. This scheme improves the pre-inversion effect of the blood to be imaged by extending the duration of the additional inversion pulse signal, which is beneficial for enhancing the imaging contrast of the blood to be imaged.

[0084] For example, the additional inverted pulse signal mentioned above is an arterial spin labeling pulse signal, wherein the arterial spin labeling pulse signal is used to label the blood in the labeling region with arterial spin.

[0085] The aforementioned arterial spin labeling pulse signal can be the labeling pulse signal used in Arterial Spin Labeling (ASL) technology. Based on the arterial spin labeling pulse signal, arterial spin labeling can be performed on blood flowing into the imaging area. For example, the blood flow status in the anterior cerebral artery and anterior inferior cerebellar artery of a target subject can be determined to achieve qualitative research on cerebral blood vessels.

[0086] According to the above-described scheme of the present invention, arterial spin labeling is performed on the blood in the labeled area. After the labeled blood flows into the imaging area, it can be used for more accurate qualitative studies of the imaging area. In particular, it can be used for qualitative studies of areas where arterial blood flow is complex, such as the brain and kidneys of the target subject.

[0087] For example, arterial spin labeling may include any one of the following: continuous arterial spin labeling and pseudo-continuous arterial spin labeling.

[0088] Continuous Arterial Spin Labeling (CASL) can effectively label the blood to be imaged by using a long-duration radio frequency pulse signal sequence to invert the net magnetization vector of hydrogen atoms in the labeling region, thereby improving the imaging contrast of the blood.

[0089] Pseudo-Continuous Arterial Spin Labeling (pCASL) can achieve an effect similar to continuous arterial spin labeling by using multiple short-duration, high-intensity radiofrequency pulse sequences, which helps to reduce adverse effects on the target object.

[0090] According to the above-described scheme of the present invention, continuous arterial spin labeling or pseudo-continuous arterial spin labeling can be used to label the blood to be imaged, thereby improving the imaging contrast of the blood. Furthermore, the above scheme is highly flexible, allowing users to use different labeling methods according to actual needs, which is beneficial for improving the adaptability of magnetic resonance blood imaging to different scenarios.

[0091] For example, performing a second inversion operation on the blood in the marked region of the target object as described above may include: performing a second inversion operation on the blood in the marked region using a (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.

[0092] The effective range of the (i+1)th inversion pulse signal can be expanded. For example, the effective range of the inversion pulse signal may include the marked region and the aforementioned background suppression region. In this example, the (i+1)th inversion pulse signal is used not only to perform a first inversion operation on the tissue in the background suppression region, but also to perform a second inversion operation on the blood in the marked region.

[0093] Referring to the example of N=4 above, the range of action of inverted pulse signal 1 can include the imaging area, the range of action of inverted pulse signal 2 can include the marking area and the imaging area, the range of action of inverted pulse signal 3 can include the imaging area, and the range of action of inverted pulse signal 4 can include the marking area and the imaging area.

[0094] 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 blood imaging to different scenarios.

[0095] For example, the length of the marked region along the flow direction of the blood to be imaged is equal to a first value. The first value is the product of the time interval between the (i+1)th inverted pulse signal and the i-th inverted pulse signal from the end and the blood flow velocity of the blood to be imaged.

[0096] The background suppression region can be extended by a first numerical value 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 / ms and the aforementioned time interval is 300 ms, then the first value 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-invert the net magnetization vector of the blood about to flow into the imaging region using the (i+1)th inversion pulse signal from the end.

[0097] In practical scenarios, the blood to be imaged can be venous blood or arterial blood. Since the blood flow velocity of venous blood is generally lower than that of arterial blood, the first value of the first marked region can be lower than the first value of the second marked region. Specifically, the first value of the first marked region can be the product of the time interval between the (i+1)th and the ith (i)th inverted pulse signal from the end of the spectrum and the blood flow velocity of the venous blood to be imaged. Similarly, the first value of the second marked region can be the product of the time interval between the (i+1)th and the ith (i)th (i)th inverted pulse signal from the end of the spectrum and the blood flow velocity of the arterial blood to be imaged.

[0098] It should be understood that the time interval between the (i+1)th inverted pulse signal and the ith inverted pulse signal can vary with i. In other words, the length of the marked region can be different for different inverted pulse signals. Referring to the example of N=4 above, 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 effective range of inverted pulse signal 4 can include the background suppression region and the third marked region, and the effective range of inverted pulse signal 2 can include the background suppression region and the fourth marked region. Since the time interval between inverted pulse signals 4 and 3 is greater than the time interval between inverted pulse signals 2 and 1, the length of the third marked region can be greater than the length of the fourth marked region.

[0099] 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. This helps to reduce the configuration cost of the host computer and scanner, and improves the adaptability of magnetic resonance blood imaging 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, effectively improving the imaging contrast, but also avoids an excessively large marked area, thus avoiding wasted resources.

[0100] As described above, step S110, generating a layer-selected saturation pulse signal in at least the imaging region of the target object, may include: generating a layer-selected saturation pulse signal in the background suppression region of the target object.

[0101] The background suppression region includes the imaging region. Both the background suppression region and the imaging region share the same edges adjacent to the labeled region. (See again...) Figure 2 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.

[0102] Refer again Figure 2 In the horizontal direction, the location of the background suppression region coincides with the location of the imaging region. In the vertical direction, the length of the background suppression region is longer than the length of the imaging region. The layer selection saturation pulse signal and N inversion pulse signals are collectively referred to as the target pulse signal. The second value 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 blood to be suppressed can be blood that the user is not interested in. For example, if the user is interested in the flow of arterial blood in the brain, the aforementioned blood to be suppressed may include venous blood in the brain. Figure 2 In the illustrated embodiment, a total of four second values ​​are included. Specifically, the second values ​​include the product of the time interval between inverted pulse signal 1 and inverted pulse signal 2 and the blood flow velocity of the blood to be suppressed, the product of the time interval between inverted pulse signal 2 and inverted pulse signal 3 and the blood flow velocity of the blood to be suppressed, etc. In the flow direction of the blood to be imaged, the length of the background suppression region is greater than or equal to the maximum value among the second values. This ensures that the signals of all blood flowing into the imaging region to be suppressed can be sufficiently and effectively suppressed, avoiding interference with the signal of the blood to be imaged.

[0103] Further, step S120, which involves sequentially generating N inversion pulse signals in at least the imaging region to perform a first inversion operation on the tissue in at least the imaging region, may include: sequentially generating N inversion pulse signals in the background suppression region to perform a first inversion operation on the tissue in the background suppression region.

[0104] 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 includes 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. 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.

[0105] For example, step S130, acquiring magnetic resonance signals of tissue in the imaging area and generating a magnetic resonance image based on the acquired magnetic resonance signals, may include steps S131 and S132.

[0106] In step S131, magnetic resonance signals of the tissue are acquired in the imaging region based on the center-priority sampling mode of K-space. Furthermore, data is filled into the K-space based on the acquired magnetic resonance signals.

[0107] 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.

[0108] 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.

[0109] refer to Figure 2The K-space shown in the lower right corner allows us to first collect the data corresponding to the dark gray portion, and then collect the data corresponding to the light gray portion. It can be understood that the data corresponding to the dark gray portion in the K-space represents the data collected from time t1 to time t2, and the data corresponding to the light gray portion represents the data collected from time t2 to time t3.

[0110] In step S132, the data in the filled K space is subjected to inverse Fourier transform to obtain a magnetic resonance image.

[0111] Data in the K-space can be converted to data in the spatial domain through inverse Fourier transform to obtain magnetic resonance images. It should 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.

[0112] 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 data in the filled K-space is subjected to inverse Fourier transform processing to obtain a magnetic resonance image. 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 images that show the true physical differences between the imaging tissues and is more in line with the actual needs of users.

[0113] For example, step S130, acquiring magnetic resonance signals of tissue in the imaging area and generating a magnetic resonance image based on the acquired magnetic resonance signals, may further include steps S133 to S135.

[0114] In step S133, for each target coding gradient, sub-steps 1 and 2 are performed until the data in each row 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 space corresponding to the target coding gradient is updated.

[0115] The target encoding gradient is the phase encoding gradient corresponding to a preset region in the K-space. This preset region can be determined by the developer or user according to actual needs, and this embodiment of the invention does not impose any limitations. For example, the preset region can be the central region mentioned above, or it can be a portion of the central region.

[0116] In step S134, the updated data is subjected to inverse Fourier transform to obtain the background image.

[0117] The execution process of step S134 is similar to that of step S132 above, and will not be repeated here for the sake of brevity.

[0118] Steps S133 to S135 are executed after step S132. (Refer to the previous section for further details.) Figure 2 During the time interval between time t3 and time t4, steps S133 and S134 are executed. As time progresses, due to the relaxation phenomenon of hydrogen atoms, the intensity of the signals generated by various tissues in the imaging region gradually increases towards 1. It is understandable that the execution of steps S131 and S132 requires a certain amount of time (…). Figure 2 (Times t1 to t3). When step S133 is executed, the signals of each tissue have largely recovered to their initial signal strength. Therefore, the images obtained through steps S133 and S134 can be considered as background images of blood vessels in the imaging area.

[0119] Step S135: The magnetic resonance image is fused with the background image to obtain a fused image.

[0120] The magnetic resonance image and the background image can be superimposed and fused using preset coefficients. It should be understood that before fusion, one or both of the magnetic resonance image and the background image can be processed through 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 magnetic resonance image to primarily display blood vessels. In other examples, minimum projection, 3D segmentation reconstruction, and other methods can be used to process the magnetic resonance image and / or the background image.

[0121] 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 can mainly provide blood flow information, and the background image can mainly provide background information. Therefore, the obtained fused image can provide richer information for user analysis, which is beneficial for qualitative research on the target object.

[0122] For example, the preset region can be the central region in the K space.

[0123] According to the above-described scheme of the present invention, the central region in K-space is typically related to the low-frequency components in the image, which can represent the basic structural information of the tissue in the image. Therefore, re-acquiring data only in the central region can help quickly generate a background image that reflects the true physical differences between the imaging tissues, thereby improving the overall efficiency of magnetic resonance imaging.

[0124] This invention also provides a magnetic resonance blood imaging device. Figure 8 A schematic block diagram of a magnetic resonance blood imaging device 200 according to an embodiment of the present invention is shown. (In conjunction with...) Figure 8 As shown, the magnetic resonance blood imaging device 200 includes a processor 210 and an actuator 220. The processor 210 is configured to control the actuator 220 to perform the following steps: generating a layer-selective saturation pulse signal in at least an imaging region of a target object; sequentially generating N inversion pulse signals in at least the imaging region to perform a first inversion operation on the tissue in at least the imaging region. Specifically, after or simultaneously with performing the first inversion operation on the blood in the imaging region using the (i+1)th inverse of the N inversion pulse signals, and before performing the first inversion operation on the blood in the imaging region using the ith inverse of the N inversion pulse signals, a second inversion operation is performed on the blood in a marker region of the target object. i is a positive odd number less than N, the marker region is adjacent to the imaging region, and the blood to be imaged flows into the imaging region through the marker region. Magnetic resonance signals of the tissue in the imaging region are acquired, and a magnetic resonance image is generated based on the acquired magnetic resonance signals.

[0125] The aforementioned execution device 220 may include a scanner. The scanner is used to apply a main magnetic field, radio frequency pulse signals, and acquire magnetic resonance signals. The specific functions of the scanner can be found in the relevant description of step S110.

[0126] For example, the processor 210 controls the execution device 220 to perform a second inversion operation on the blood in the marked area of ​​the target object, and is further configured to control the execution device 220 to perform: generate another inversion pulse signal in the marked area of ​​the target object only between the end time of the generation of the (i+1)th inversion pulse signal and the start time of the generation of the i-th inversion pulse signal, so as to perform a second inversion operation on the blood in the marked area.

[0127] For example, the additional inverted pulse signal is generated at the end of the generation of the (i+1)th inverted pulse signal and continues until the start of the generation of the ith inverted pulse signal.

[0128] For example, another inverted pulse signal is an arterial spin labeling pulse signal, wherein the arterial spin labeling pulse signal is used to label the blood in the labeling region with arterial spin.

[0129] For example, arterial spin labeling includes any one of the following: continuous arterial spin labeling and pseudo-continuous arterial spin labeling.

[0130] For example, the processor 210 controls the execution device 220 to perform a second inversion operation on the blood in the marked area of ​​the target object, and is further configured to control the execution device 220 to perform: perform a second inversion operation on the blood in the marked area using the (i+1)th inversion pulse signal from the end, wherein the (i+1)th inversion pulse signal from the end is generated in at least the imaging area and the marked area.

[0131] For example, the length of the marked region along the flow direction of the blood to be imaged is equal to a first value, wherein the first value is the product of the time interval between the (i+1)th inverted pulse signal and the i-th inverted pulse signal from the end and the blood flow velocity of the blood to be imaged.

[0132] For example, processor 210 controls execution device 220 to generate a layer-select saturated pulse signal in at least the imaging region of the target object, and is further configured to control execution device 220 to generate a layer-select saturated pulse signal in the background suppression region of the target object, wherein the background suppression region includes the imaging region, the background suppression region and the imaging region have the same edge adjacent to the marker region, and the length of the background suppression region is greater than or equal to the maximum value in the flow direction of the blood to be imaged, the second value including 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 including a layer-selected saturated pulse signal and N inverted pulse signals.

[0133] The processor 210 controls the execution device 220 to execute the generation of N inversion pulse signals in at least the imaging region to perform a first inversion operation on the tissue in at least the imaging region, and is further configured to control the execution device 220 to execute the generation of N inversion pulse signals in the background suppression region to perform a first inversion operation on the tissue in the background suppression region.

[0134] For example, processor 210 controls execution device 220 to acquire magnetic resonance signals of tissue in the imaging region and generate a magnetic resonance image based on the acquired magnetic resonance signals. Further configured, processor 210 controls execution device 220 to: acquire magnetic resonance signals of tissue in the imaging region based on a center-priority sampling mode in K-space, and fill the K-space with data based on the acquired magnetic resonance signals. The data in the filled K-space is then subjected to an inverse Fourier transform to obtain the magnetic resonance image.

[0135] For example, processor 210 controls execution device 220 to acquire magnetic resonance signals of tissue in the imaging region and generate a magnetic resonance image based on the acquired magnetic resonance signals. Further configured, processor 210 controls execution device 220 to perform the following sub-steps 1 and 2 for each target coding gradient until the data in each row of the space corresponding to each target coding gradient in the filled K-space is updated to obtain updated data. Here, the target coding gradient is the phase coding gradient corresponding to a preset region in the K-space. Sub-step 1: Acquire magnetic resonance signals in the imaging region based on the target coding gradient. Sub-step 2: Update the data in the row of the space corresponding to the target coding gradient. Perform inverse Fourier transform on the updated data to obtain a background image. Fuse the magnetic resonance image with the background image to obtain a fused image.

[0136] For example, the preset area is the central area in the K space.

[0137] Furthermore, according to another aspect of the present invention, a non-volatile storage medium is provided, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor performs corresponding steps of the magnetic resonance blood imaging method described in the embodiments of the present invention, and is used to implement corresponding modules in the magnetic resonance blood imaging device described in the embodiments of the present invention. The non-volatile storage medium may, for example, include 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 computer-readable non-volatile storage medium may be any combination of one or more computer-readable non-volatile storage media.

[0138] According to another aspect of the present invention, a computer program product is also provided, comprising computer program instructions that, when executed by a processor, cause the processor to perform corresponding steps of the aforementioned magnetic resonance blood imaging method. Those skilled in the art can understand the specific implementation schemes of the aforementioned device, non-volatile storage medium, and computer program product by reading the above description of the magnetic resonance blood imaging method; for the sake of brevity, further details are omitted here.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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 units of any method or apparatus so disclosed can 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.

[0145] 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.

[0146] 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 blood imaging device according to embodiments of the present invention. The present invention can also be implemented as a device program (e.g., a computer program and computer program product) for performing some or all of the methods described herein. Such a program 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.

[0147] 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 devices, several of these devices 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.

[0148] 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 imaging method for blood, characterized in that, The method includes: Generate a layer-selected saturation pulse signal in at least the imaging region of the target object; N inversion pulse signals are sequentially generated in at least the imaging region 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 from 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 from the N inversion pulse signals, a second inversion operation is performed on the blood in the marked region of the target object. Here, 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 via the marked region. Magnetic resonance signals of tissue in the imaging region are acquired, and a magnetic resonance image is generated based on the acquired magnetic resonance signals.

2. 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: Only between the end of the generation of the (i+1)th inverted pulse signal and the start of the generation of the ith inverted pulse signal, another inverted pulse signal is generated in the marked area of ​​the target object to perform a second inverted operation on the blood in the marked area.

3. The method as described in claim 2, characterized in that, The additional inverted pulse signal is generated at the end of the generation of the (i+1)th inverted pulse signal and continues until the start of the generation of the ith inverted pulse signal.

4. The method as described in claim 2, characterized in that, The additional inverted pulse signal is an arterial spin labeling pulse signal, wherein the arterial spin labeling pulse signal is used to label the blood in the labeling region with arterial spin.

5. The method as described in claim 4, characterized in that, The arterial spin markers include any one of the following: continuous arterial spin markers and pseudo-continuous arterial spin markers.

6. 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: The blood in the marked region is subjected to the second inversion operation 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.

7. The method as described in claim 6, characterized in that, The length of the marked region along the flow direction of the blood to be imaged is equal to a first value, wherein the first value is the product of the time interval between the (i+1)th inverted pulse signal and the i-th inverted pulse signal from the end and the blood flow velocity of the blood to be imaged.

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

9. The method according to any one of claims 1 to 8, 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 data in the filled K-space are then subjected to inverse Fourier transform to obtain the magnetic resonance image.

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 a 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 a preset 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 as described in claim 10, characterized in that, The preset area is the central area in the K-space.

12. A magnetic resonance blood imaging device, characterized in that, The device includes a processor and an execution device, the processor being configured to control the execution device to perform the following steps: Generate a layer-selected saturation pulse signal in at least the imaging region of the target object; N inversion pulse signals are sequentially generated in at least the imaging region 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 from 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 from the N inversion pulse signals, a second inversion operation is performed on the blood in the marked region of the target object. Here, 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 via the marked region. Magnetic resonance signals of tissue in the imaging region are acquired, and a magnetic resonance image is generated based on the acquired magnetic resonance signals.

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

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