Magnetic resonance blood imaging method and device and non-volatile storage medium

Abstract

The invention provides a magnetic resonance blood imaging method, magnetic resonance blood imaging equipment and a nonvolatile storage medium. The method comprises the following steps: generating a layer selection saturation pulse signal in an imaging area; n inversion pulse signals are sequentially generated in the imaging area so as to perform first inversion operation on the tissue in the imaging area, and after or at the same time of performing the first inversion operation on the tissue in the imaging area by using the (i + 1)-th inversion pulse signal in the N inversion pulse signals, the (i + 1)-th inversion pulse signal in the N inversion pulse signals is converted into the (i + 1)-th inversion pulse signal, before the first inversion operation is carried out on the tissue in the imaging area by utilizing the inverse ith inversion pulse signal in the N inversion pulse signals, the second inversion operation is carried out on the blood in the marking area, and i is a positive odd number smaller than N; magnetic resonance signals of the tissue in the imaging region are acquired and a magnetic resonance image is generated. The total time consumption of imaging is shorter, and the generation efficiency of the magnetic resonance image is improved. And moreover, the influence of the pose of the target object on the contrast of the magnetic resonance image can be reduced.

Description

Technical Field

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

[0002] Magnetic resonance imaging (MRI) is a non-invasive medical imaging technique that uses radiofrequency pulses and gradient magnetic fields to produce detailed images of the human body's internal structures. Unlike X-rays or CT scans, MRI does not use ionizing radiation, making it safer for the subjects. However, existing MRI technology has the following issues, particularly in applications requiring high-contrast images and rapid imaging.

[0003] In order to improve the visibility of blood in certain areas of the imaging object, traditional MRI often relies on the use of contrast agents (such as gadolinium-based contrast agents). Although this solution will increase the contrast of magnetic resonance images, the contrast agent may impose a metabolic burden on the kidneys of the imaging subject. In addition, the use of contrast agents also increases the cost of imaging. In other solutions, magnetic resonance images are generated based on subtraction technology. Subtraction technology requires the acquisition of at least two magnetic resonance images and the use of subtraction to achieve blood imaging. Therefore, the imaging process takes too long and the imaging efficiency is low. On the one hand, this seriously affects the imaging subject's experience. On the other hand, it is difficult for the imaging subject to maintain a constant posture during a long imaging process. Changes in posture will result in poor contrast in the magnetic resonance images obtained by subtraction. Summary of the Invention

[0004] The present invention is proposed in view of the above problems. The present invention provides a magnetic resonance 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, which includes: generating a layer-selective saturation pulse signal in at least an imaging area of a target object; sequentially generating N inversion pulse signals in at least the imaging area to perform a first inversion operation on tissue in at least the imaging area, wherein after or simultaneously with performing the first inversion operation on tissue in at least the imaging area using the reciprocal (i+1)th inversion pulse signal among the N inversion pulse signals, and before performing the first inversion operation on tissue in at least the imaging area using the reciprocal (i)th inversion pulse signal among the N inversion pulse signals, a second inversion operation is performed on blood in a marking area of the target object, where i is a positive odd number less than N, the marking area is adjacent to the imaging area, and the blood to be imaged flows into the imaging area via the marking area; acquiring magnetic resonance signals of the tissue in the imaging area, and generating a magnetic resonance image based on the acquired magnetic resonance signals.

[0006] Exemplarily, performing a second inversion operation on the blood in the marked area of the target object includes:

[0007] 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, another inversion pulse signal is generated in the marked area of the target object to perform a second inversion operation on the blood in the marked area.

[0008] Exemplarily, another inversion pulse signal is generated at the end time of generation of the (i+1)th inversion pulse signal from the last and continues until the start time of generation of the (i)th inversion pulse signal from the last.

[0009] Exemplarily, the additional inversion pulse signal is an arterial spin labeling pulse signal, wherein the arterial spin labeling pulse signal is used to perform arterial spin labeling on blood in the labeling region.

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

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

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

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

[0014] Exemplarily, generating a slice-selective saturation pulse signal in at least an imaging region of a target object includes:

[0015] generating a slice-selected saturation pulse signal in a background suppression region of the target object, wherein the background suppression region includes an imaging region, the background suppression region and the imaging region have the same edge adjacent to the marking region, and in a flow direction of blood to be imaged, a length of the background suppression region is greater than or equal to a maximum value of second values, wherein the second value includes a product of a time interval between every two adjacent target pulse signals and a blood flow velocity of the blood to be suppressed, and the target pulse signal includes the slice-selected saturation pulse signal and N inversion pulse signals;

[0016] Sequentially generating N inversion pulse signals in at least an imaging region to perform a first inversion operation on tissue in at least the imaging region includes:

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

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

[0020] The data in the filled K space is subjected to inverse Fourier transform processing to obtain a magnetic resonance image.

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

[0022] For each target encoding gradient, perform the following steps until the data in a row of space corresponding to each target encoding gradient in the filled K space is updated to obtain updated data, where the target encoding gradient is the phase encoding gradient corresponding to the preset area 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 a row of space corresponding to the target encoding gradient;

[0025] Perform inverse Fourier transform on the updated data to obtain a background image;

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

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

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

[0029] generating a slice-selective saturation pulse signal in at least an imaging region of the target object;

[0030] sequentially generating N inversion pulse signals in at least an imaging region to perform a first inversion operation on tissue in at least the imaging region, wherein after or simultaneously with performing the first inversion operation on the tissue in at least the imaging region using the reciprocal (i+1)th inversion pulse signal among the N inversion pulse signals and before performing the first inversion operation on the tissue in at least the imaging region using the reciprocal (i)th inversion pulse signal among the N inversion pulse signals, a second inversion operation is performed on blood in a marking region of the target object, where i is a positive odd number less than N, the marking region is adjacent to the imaging region, and the blood to be imaged flows into the imaging region via the marking region;

[0031] Magnetic resonance signals of tissue in an imaging region 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 provided, on which computer program instructions are stored, and the computer program instructions are used to execute the above-mentioned magnetic resonance blood imaging method when running.

[0033] According to another aspect of the present invention, a computer program product is further provided, wherein the computer program product comprises computer program instructions, and the computer program instructions are used to execute the above-mentioned magnetic resonance blood imaging method when running.

[0034] In an embodiment of the present invention, by applying a slice-selective 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. Furthermore, a second inversion operation is performed on the blood in the marked region, thereby enhancing the imaging contrast of the blood to be imaged in the imaging region. Because subtraction techniques are not required to generate magnetic resonance images, the overall magnetic resonance imaging process of the embodiment of the present application is shortened, significantly improving imaging efficiency. Finally, this helps reduce the impact of the target subject's posture on the contrast of the magnetic resonance image. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other objects, features, and advantages of the present invention will become more apparent through a more detailed description of the embodiments of the present invention with reference to the accompanying drawings. The accompanying drawings are provided to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and are not intended to limit the present invention. In the drawings, the same reference numerals generally represent the same components or steps.

[0036] Figure 1 FIG2 shows a schematic flow chart of a magnetic resonance blood imaging method according to an embodiment of the present invention;

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

[0038] Figure 3 A simulation diagram showing changes in signal intensity of tissue over time according to one embodiment of the present invention is shown;

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

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

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

[0042] Figure 7 A simulation diagram showing changes in the signal intensity of arterial blood with blood inflow time according to one embodiment of the present invention; and

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

[0044] In order to make the purpose, technical solutions and advantages of the present invention more apparent, exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein. Based on the embodiments of the present invention described in the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0045] In order to at least partially solve the above problems, an embodiment of the present invention provides a magnetic resonance blood imaging method. Figure 1FIG. 1 shows a schematic flow chart of a magnetic resonance blood imaging method according to an embodiment of the present invention. Figure 1 As shown, the method may include the following steps S110 to S130.

[0046] In step S110 , a slice-selective saturation pulse signal is generated in at least an imaging region of a target object.

[0047] For example, a magnetic resonance imaging system can be used to acquire magnetic resonance signals from a target subject. The magnetic resonance imaging system may include a scanner, an inspection platform, and a host computer. The scanner has a space for accommodating the inspection platform. The target subject can lie flat on the inspection platform, which can then be moved into the space. Hydrogen atoms in the target subject's tissue are affected by the magnetic force of the main magnetic field (also known as the B0 magnetic field). From a macroscopic perspective, this can be seen as a net magnetization vector formed by several hydrogen atoms with a direction close to the Z-axis. The Z-axis direction can be the direction from the head placement area to the foot placement area on the inspection platform. The head placement area can be used to place the target subject's head, and the foot placement area can be used to place the target subject's feet. When a radio frequency pulse signal (such as the slice-selective saturation pulse signal and inversion pulse signal in the embodiments of the present application) is applied to at least the imaging area of the target subject, some hydrogen atoms in the application area absorb energy, transitioning from a low-energy state to a high-energy state. From a macroscopic perspective, this can be seen as a change in the direction of the net magnetization vector. After the RF pulse signal is applied, the high-energy hydrogen atoms relax, generating an electrical signal that is received by the scanner. The scanner converts the electrical signal into a digital signal and sends it to the host computer, which uses the MRI algorithm to generate an MRI image.

[0048] The imaging area of the target object may be a portion of the target object's body that the user desires to observe. For example, if the user desires to observe the target object's head, the imaging area may be the target object's head area, or a portion of the head area. For another example, if the user desires to observe the target object's kidneys, the imaging area may be the target object's kidney area, or a portion of the kidney area. It should be understood that the user may also select the imaging area of the target object based on actual needs, and this embodiment of the present invention does not impose any limitation thereto.

[0049] The slice-selective saturation pulse signal can be used to adjust the direction of the net magnetization vector to be close to the X-axis. The X-axis can be the direction from the left-hand placement area to the right-hand placement area on the examination platform. The left-hand placement area can be used to place the subject's left hand, and the right-hand placement area can be used to place the subject's right hand. Through this process, the components of the net magnetization vector in the planes containing the X- and Y-axes increase, and as the hydrogen atoms precess, a time-varying magnetic resonance signal is generated. The Y-axis can be a vertical axis. For example, if the signal intensity of the magnetic resonance signal (hereinafter referred to as the signal) corresponding to untreated arterial blood is taken as 1, and the signal intensity of the arterial blood after applying the inversion pulse signal is taken as -1, then, ideally, the slice-selective saturation pulse signal can adjust the signal intensity of the signal generated by the tissue in the application area to 0. It will be understood that the tissue in the application area can include solid tissues such as fat and brain tissue, as well as fluid tissues such as blood and cerebrospinal fluid. Therefore, the slice-selective saturation pulse signal can achieve background signal suppression, such as fat suppression and fluid suppression such as cerebrospinal fluid. It should be understood that the above-mentioned layer-selective saturation pulse signal may include a single pulse or multiple pulses.

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

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

[0053] Similar to the slice-selective saturation pulse signal, the inversion pulse signal can be generated only in the imaging area. Alternatively, the inversion pulse signal can be generated in a larger area than the imaging area. This larger area includes the imaging area. It will be appreciated that the application area of the inversion pulse signal can be the same as or different from the application area of the slice-selective saturation pulse signal. For ease of description, the following embodiments illustrate the case where both application areas are the same background suppression area.

[0054] N can be a preset positive integer representing the total number of inversion pulse signals used to perform the first inversion operation. The specific value can be determined by the developer based on actual conditions. It should be understood that in related art, the inversion recovery time can be related to the value of N, the blood transit time (BTT), and other factors. The inversion recovery time can be used to indicate the optimal time for image acquisition.

[0055] It should be understood that the numerical values mentioned in the embodiments of the present application are all values under ideal conditions, and there may be deviations in the numerical values under actual conditions.

[0056] In one example, N may be 4. Figure 2 , Figure 2 FIG2 shows a schematic diagram of a magnetic resonance blood imaging method according to an embodiment of the present invention. Figure 2, the inversion pulse signals are arranged in reverse chronological order, and the N inversion pulse signals may include inversion pulse signals 1 to 4. Taking the time point of acquiring the magnetic resonance signal as time 0, the generation start time of the slice-selective saturation pulse signal may be -2000 milliseconds, the generation start time of inversion pulse signal 4 may be approximately -1652.1 milliseconds, the generation start time of inversion pulse signal 3 may be approximately -987.7 milliseconds, the generation start time of inversion pulse signal 2 may be approximately -435.8 milliseconds, and the generation start time of inversion pulse signal 1 may be approximately -107 milliseconds. It should be understood that the time interval between the generation start time of the slice-selective saturation pulse signal and time 0 can be set according to the actual needs of the developer and is not limited in this embodiment of the present application. For example, for the elderly, the time interval can be set longer, while for the younger ones, the time interval can be set shorter.

[0057] In one example, after performing a first inversion operation on tissue in the background suppression region or the imaging region using the (i+1)th inversion pulse signal from the N inversion pulse signals, and before performing the first inversion operation on tissue in the background suppression region or the imaging region using the (i)th inversion pulse signal from the N inversion pulse signals, a second inversion operation is performed on blood in the marking region of the target object. i is a positive odd number less than N. The marking region is adjacent to the imaging region, and the blood to be imaged flows into the imaging region via the marking region. It should be understood that the blood to be imaged can be either arterial blood or venous blood.

[0058] For example, if there are a total of 4 inversion pulse signals, the 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 area or the imaging area using the second to last inversion pulse signal (for example, the inversion pulse signal 2 mentioned above), and before the first inversion operation is performed on the tissue in the background suppression area or the imaging area using the first to last inversion pulse signal (for example, the inversion pulse signal 1 mentioned above).

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

[0060] The marking area may be adjacent to the imaging area. Figure 2 shows an example in which the imaging region is a portion of the target subject's brain region. In this example, the blood to be imaged is cerebral arterial blood. Since the heart, which supplies cerebral arterial blood, is located below the brain region, the region below the brain region can be used as the aforementioned marking region. Figure 2The figure also shows an example where the imaging area is the kidney region of the target object. In this example, the 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 aforementioned marking area.

[0061] In another example, while a first inversion operation is performed on tissue in at least the imaging area using the reciprocal (i+1)th inversion pulse signal among N inversion pulse signals, and before a first inversion operation is performed on tissue in at least the imaging area using the reciprocal (i)th inversion pulse signal among N inversion pulse signals, a second inversion operation is performed on blood in the marking area of the target object.

[0062] As mentioned above, the slice-selective saturation pulse signal can adjust the signal intensity of the signal generated by the tissue in the background suppression area to 0. As time goes by, due to the relaxation phenomenon of hydrogen atoms, the signal intensity of this signal will gradually increase towards 1. At time 0 when the magnetic resonance signal is acquired after the application of N inversion pulse signals, the signal intensity of this signal can be close to 0. Figure 3 , Figure 3 FIG1 shows a simulation diagram of the signal intensity of a tissue changing over time according to an embodiment of the present invention. Figure 3 In the example, the tissue may specifically include cerebrospinal fluid (CSF), gray matter (GM), white matter (WM), and fat (Fat). In this example, N is 4, and a layer-selected saturation pulse signal may be applied in the background suppression area at -2000 milliseconds to adjust the signal intensity of the signal generated by the tissue in the background suppression area at -2000 milliseconds to 0. The blood in the background suppression area may include arterial blood and venous blood. The blood flow rate of venous blood is slower, so most of the hydrogen atoms in the venous blood will remain in the background suppression area at time 0. The signal intensity (hereinafter referred to as the first intensity) of the signal generated by the hydrogen atoms remaining in the background suppression area can be adjusted by applying N inversion pulse signals. It should be understood that the above-mentioned hydrogen atoms remaining in the background suppression area may also include hydrogen atoms of the tissue in the background suppression area. Specifically, between -2000 milliseconds and -1652.1 milliseconds, due to the relaxation phenomenon of hydrogen atoms, the first intensity will gradually increase toward 1, for example Figure 3 The signal intensity of the cerebrospinal fluid increases to 0.7. After the first inversion pulse signal performs the first inversion operation on the tissue in the background suppression area, the direction of the net magnetization vector of the cerebrospinal fluid will reverse 180 degrees, so that the first intensity of the cerebrospinal fluid is adjusted to -0.7. Through the action of N inversion pulse signals, the first intensity of the cerebrospinal fluid can be close to 0 at time 0, that is, background suppression of the cerebrospinal fluid is achieved. For another example, Figure 3 The signal intensity of the gray matter in the background suppression region increases from 0 to 0.35 between -2000 milliseconds and -1652.1 milliseconds. After the first inversion pulse signal performs the first inversion operation on the tissue in the background suppression region, the direction of the gray matter's net magnetization vector reverses 180 degrees, adjusting the gray matter's first intensity to -0.35. Through the action of N inversion pulse signals, the gray matter's first intensity is brought close to 0 at time 0, achieving background suppression for the gray matter. Background suppression for other tissues is similar and will not be detailed here.

[0063] In an embodiment of the present invention, blood to be imaged that has experienced an even number of inversion pulse signals in the imaging area appears as a positive signal during imaging. A second inversion operation is performed on the blood in the marking area before or simultaneously with the first inversion operation performed on the tissue in the background suppression area using the penultimate (i+1)th inversion pulse signal. Here, i is a positive odd number. The second inversion operation is used to pre-invert a portion of the blood to be imaged before it flows into the imaging area. Thus, blood to be imaged that has experienced an odd number of inversion pulse signals in the imaging area also appears as a positive signal during imaging due to the combined effects of the second and first inversion operations.

[0064] According to the embodiments of the present invention, the available blood inflow time is extended, and the selection range of the inversion recovery time is wider, which is conducive to decoupling the blood inflow time and the inversion recovery time and improving the scenario adaptability.

[0065] In step S130 , 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.

[0066] After steps S110 and S120, magnetic resonance signals of tissue in the imaging region can be acquired at time 0. In some examples, multiple preset phase encoding gradients can be sequentially applied in at least the imaging region using gradient coils in the scanner to sequentially form multiple gradient magnetic fields. Each phase encoding gradient can correspond to a row in K-space. Magnetic resonance signals acquired in the gradient magnetic field formed based on the phase gradient encoding can be filled into the row in K-space corresponding to the phase gradient encoding. After each row is filled, the data in the filled K-space can be converted into a magnetic resonance image using an inverse Fourier transform. In one example, magnetic resonance signals corresponding to only a portion of K-space can be acquired, and then, based on the conjugate symmetry of K-space, a preset algorithm can be used to complete the unfilled space in K-space. A magnetic resonance image is then generated using the data in the fully filled K-space. It should be understood that if 3D imaging technology is used, the data in K-space can be acquired sequentially in blocks, but this is not a limitation in the present embodiment.

[0067] In some embodiments, magnetic resonance images may also be generated using imaging techniques known in the art, such as MP-RAGE (Magnetization Prepared Rapid Gradient Echo) imaging, GRE (Gradient Recalled Echo) imaging, FSE (Fast Spin Echo) imaging, and bSSFP (balanced Steady State free processing) imaging. These techniques include stack-of-star golden angle sampling (STAR) imaging, etc.

[0068] In one example, the magnetic resonance image can be processed using an image processing algorithm known in the related art before being displayed. For example, the magnetic resonance image can be subjected to feature enhancement or noise suppression. In another example, a region segmentation algorithm or model known in the related art can be used to determine a region of interest in the magnetic resonance image.

[0069] See Figure 4 and Figure 5 , Figure 4 FIG. 1 is a schematic diagram showing a magnetic resonance image of a head according to an embodiment of the present invention, Figure 5 FIG2 shows a schematic diagram of a magnetic resonance image of a kidney according to an embodiment of the present invention. Figure 4 and Figure 5 , the pixels with larger pixel values in the magnetic resonance image are the pixels corresponding to the blood to be imaged. It can be seen that the imaging contrast of the blood to be imaged is relatively high, which is helpful in assisting the user to conduct qualitative research on the brain or kidney of the target object.

[0070] According to the above-mentioned solution provided by the embodiment of the present invention, on the one hand, by applying a layer-selective saturation pulse signal and an inversion pulse signal to at least the imaging area, the background signal in the imaging area 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 area, thereby enhancing the imaging contrast of the blood to be imaged in the imaging area. Because there is no need to use subtraction technology to generate the magnetic resonance image, the total time required for the magnetic resonance imaging process of the embodiment of the present application is shortened, significantly improving imaging efficiency. Finally, this helps to reduce the impact of the target object's posture on the contrast of the magnetic resonance image.

[0071] Illustratively, the above-mentioned second inversion operation on the blood in the marked area of the target object may include: generating another inversion pulse signal in the marked area of the target object only between the end time of generation of the penultimate (i+1) inversion pulse signal and the start time of generation of the penultimate (i) inversion pulse signal, so as to perform the second inversion operation on the blood in the marked area.

[0072] From a macroscopic perspective, the additional inversion pulse signal can be used to implement a second inversion operation. The second inversion operation can be to reverse the direction of the net magnetization vector formed by the tissue in the marked area. For example, the second inversion operation can reverse the direction of the net magnetization vector by 180 degrees. In one example, the target parameters of the additional inversion pulse signal can be the same as the target parameters of the inversion pulse signal used to implement the first inversion operation in step S120. In another example, a pulse signal with a different pulse type that can reverse the direction of the net magnetization vector can also be used. The additional inversion pulse signal can include a single pulse or multiple pulses, and the embodiment of the present invention is not limited thereto.

[0073] exist Figure 2In the illustrated embodiment, an additional inversion pulse signal for performing a second inversion operation is generated between the time when inversion pulse signal 1 is generated (i.e., -107 milliseconds) and the time when inversion pulse signal 2 is generated (i.e., -435.8 milliseconds). An additional inversion pulse signal for performing a second inversion operation is also generated between the time when inversion pulse signal 3 is generated (i.e., -987.7 milliseconds) and the time when inversion pulse signal 4 is generated (i.e., -1652.1 milliseconds). Arterial blood flowing into the imaging region between time 0 and time -107 milliseconds does not experience any inversion pulse signals. Arterial blood flowing into the imaging region between time -435.8 milliseconds and time -987.7 milliseconds and before time -1652.1 milliseconds has already experienced an even number of inversion pulse signals applied in the background suppression region by time 0. For the arterial blood flowing into the imaging area between time -107 milliseconds and time -435.8 milliseconds, by time 0, it not only experienced inversion pulse signal 1 applied to the background suppression area, but also experienced another inversion pulse signal applied to the marking area before flowing into the background suppression area. In other words, the arterial blood in the imaging area between time -107 milliseconds and time -435.8 milliseconds underwent a pre-inversion operation (i.e., a second inversion operation) in the marking area through which it flowed. Similarly, the arterial blood flowing into the imaging area between time -1652.1 milliseconds and time -987.7 milliseconds experienced, by time 0, another inversion pulse signal in the marking area, inversion pulse signal 3, inversion pulse signal 2, and inversion pulse signal 1. Thus, by time 0, all arterial blood in the imaging area had experienced an even number of inversion pulse signals. This ensures that the blood that successively flows into the imaging area has a positive signal at time 0, maintaining sufficient signal strength.

[0074] See Figure 6 and Figure 7 , Figure 6 FIG2 shows a simulation diagram showing the change of the signal intensity of arterial blood over time according to one embodiment of the present invention. Figure 7 A simulation diagram showing the variation of the signal intensity of arterial blood with blood inflow time according to one embodiment of the present invention is shown.

[0075] Combine Figure 6 and Figure 7, if the arterial blood (in this embodiment, it can be regarded as the blood to be imaged) flows in for a time 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 marking area before the generation start time of the inversion pulse signal 1. The initial signal intensity of the signal of the arterial blood (hereinafter referred to as the second intensity) is 1. Another inversion pulse signal can perform a second inversion operation on the blood in the marking area to adjust the second intensity 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 intensity will gradually increase toward 1. Here, Figure 6 For example, for arterial blood with a blood inflow time of -210 milliseconds, the second intensity of the arterial blood may increase to -0.9. In this example, performing a first inversion operation on the tissue in the imaging area using the inversion pulse signal 1 may include performing a first inversion operation on the arterial blood flowing into the imaging area to adjust the second intensity to 0.9. Due to the relaxation of hydrogen atoms, the second intensity gradually increases toward 1. At time 0, the second intensity is approximately 0.95.

[0076] If the blood inflow time of the arterial blood 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), the arterial blood is located in the marked area before the start time of the generation of the inversion pulse signal 2. The initial signal intensity of the signal of the arterial blood (hereinafter referred to as the third intensity) is 1. There is no other inversion pulse signal between the inversion pulse signal 3 and the inversion pulse signal 2, so the third intensity is almost unchanged between the end time of the generation of the inversion pulse signal 3 and the start time of the generation of the inversion pulse signal 2. At the start time of the generation of the inversion pulse signal 2, the arterial blood has 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 above-mentioned arterial blood flowing into the imaging area so that the third intensity is adjusted to -1. Due to the relaxation phenomenon of hydrogen atoms, the third intensity will gradually increase toward 1. Here, Figure 6 For example, for arterial blood flowing into the imaging area for a time of -540 milliseconds, the third intensity of the arterial blood can increase to -0.6. Inversion pulse signal 1 performs a first inversion operation on tissue in the imaging area, which may include: performing a first inversion operation on the arterial blood flowing into the imaging area to adjust the third intensity to 0.6. Due to the relaxation phenomenon of hydrogen atoms, the third intensity gradually increases toward 1. At time 0, the third intensity is approximately 0.65.

[0077] If the blood inflow time of the arterial blood 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), the arterial blood is located in the marking area before the start time of the generation of the inversion pulse signal 3. The initial signal intensity of the signal of the arterial blood (hereinafter referred to as the fourth intensity) is 1. Another inversion pulse signal is generated between the end time of the generation of the inversion pulse signal 4 and the start time of the generation of the inversion pulse signal 3. The other inversion pulse signal can perform a second inversion operation on the blood in the marking area to adjust the fourth intensity to -1. At the start time of the generation of the inversion pulse signal 3, the arterial blood has flowed into the imaging area, and due to the relaxation phenomenon of hydrogen atoms, the fourth intensity will gradually increase toward 1. Here, Figure 6 Taking arterial blood with a blood inflow time of -1090 milliseconds as an example, the fourth intensity of the arterial blood may increase to -0.8. In this example, inversion pulse signal 3 performs a first inversion operation on the tissue in the imaging area, which may include: performing a first inversion operation on the arterial blood flowing into the imaging area to adjust the fourth intensity to 0.8. Due to the relaxation of hydrogen atoms, the fourth intensity gradually increases toward 1, for example, to 0.9. 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 arterial blood flowing into the imaging area to adjust the fourth intensity to -0.9. Due to the relaxation of hydrogen atoms, the fourth intensity gradually increases toward 1, in this example, to -0.5. Inversion pulse signal 1 performs a first inversion operation on the tissue in the imaging area, which may include: performing a first inversion operation on the arterial blood flowing into the imaging area to adjust the fourth intensity to 0.5. Due to the relaxation of hydrogen atoms, the fourth intensity gradually increases toward 1, and at time 0, the fourth intensity is approximately 0.55.

[0078] If the blood inflow time of the arterial blood is between -2000 and -1652.1 milliseconds (in other words, the arterial blood flows into the imaging area between -2000 and -1652.1 milliseconds), the arterial blood is located in the marking area before the generation start time of the inversion pulse signal 1. The initial signal intensity of the signal of the arterial blood (hereinafter referred to as the fifth intensity) 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 above-mentioned arterial blood flowing into the imaging area so that the fifth intensity is adjusted to -1. Due to the relaxation phenomenon of hydrogen atoms, the fifth intensity will gradually increase toward 1. Here, Figure 6Taking arterial blood with a blood inflow time of -1750 milliseconds as an example, the fourth intensity of the arterial blood may increase to -0.25. Inversion pulse signal 3 performs a first inversion operation on the tissue in the imaging area, which may include: performing a first inversion operation on the arterial blood flowing into the imaging area to adjust the fifth intensity to 0.25. Due to the relaxation of hydrogen atoms, the fifth intensity gradually increases toward 1, for example, to 0.5. 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 arterial blood flowing into the imaging area to adjust the fifth intensity to -0.5. Due to the relaxation of hydrogen atoms, the fifth intensity gradually increases toward 1, in this example, to -0.2. Inversion pulse signal 1 performs a first inversion operation on the tissue in the imaging area, which may include: performing a first inversion operation on the arterial blood flowing into the imaging area to adjust the fifth intensity to 0.2. Due to the relaxation of hydrogen atoms, the fifth intensity gradually increases toward 1, and at time 0, the fifth intensity is approximately 0.25.

[0079] According to the above-described embodiment of the present invention, an additional inversion pulse signal can be generated in the marked area of the target object only between the end of generation of the (i+1)th inversion pulse signal and the start of generation of the (i)th inversion pulse signal from the end of the last inversion pulse, thereby performing a second inversion operation on the blood in the marked area. In this embodiment, 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 short, making the second inversion operation more effective for blood about to flow into the imaging area. This ensures the contrast of the blood in the magnetic resonance image.

[0080] Exemplarily, another inversion pulse signal may be generated at the end time of generation of the (i+1)th inversion pulse signal from the last to the last and continue until the start time of generation of the (i)th inversion pulse signal from the last to the last.

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

[0082] In conjunction with the example in which N is 4 above, another inversion pulse signal can be generated in the marking area between the end time of the generation of the inversion pulse signal 2 and the start time of the generation of the inversion pulse signal 1. The duration of the inversion pulse signal can be a first duration. The first duration can be equal to the absolute value of the value obtained by subtracting the start time of the generation of the inversion pulse signal 1 from the end time of the generation of the inversion pulse signal 2. Another inversion pulse signal can also be generated in the marking area between the end time of the generation of the inversion pulse signal 4 and the start time of the generation of the inversion pulse signal 3. The duration of the inversion pulse signal can be a second duration. The second duration can be equal to the absolute value of the value obtained by subtracting the start time of the generation of the inversion pulse signal 3 from the end time of the generation of the inversion pulse signal 4.

[0083] According to the above-described embodiment of the present invention, an additional inversion pulse signal can be generated at the end of the generation of the (i+1)th inversion pulse signal from the last to the end and continue until the generation of the (i)th inversion pulse signal from the last to the end begins. By extending the duration of the additional inversion pulse signal, the above-described embodiment enhances the pre-inversion effect of the blood to be imaged, thereby facilitating enhanced imaging contrast of the blood to be imaged.

[0084] Exemplarily, the additional inversion pulse signal is an arterial spin labeling pulse signal, wherein the arterial spin labeling pulse signal is used to perform arterial spin labeling on blood in the labeling area.

[0085] The arterial spin labeling pulse signal described above may be a labeling pulse signal used in arterial spin labeling (ASL) technology. Based on the ASL pulse signal, blood flowing into the imaging region can be subjected to arterial spin labeling. For example, blood flow in the anterior cerebral artery and anterior inferior cerebellar artery of a target subject can be determined to enable qualitative analysis of cerebral blood vessels.

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

[0087] Illustratively, 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 fully label the blood to be imaged by using a long radiofrequency pulse signal sequence to reverse the net magnetization vector of hydrogen atoms in the labeled area, which is beneficial to improving the imaging contrast of the blood to be imaged.

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

[0090] According to the above-described solution of an embodiment 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 to be imaged. Furthermore, the above-described solution offers high flexibility, allowing users to use different labeling methods according to their actual needs, thereby improving the adaptability of MRI blood imaging to different scenarios.

[0091] For example, performing the second inversion operation on the blood in the marked area of the target object may include performing the second inversion operation on the blood in the marked area using the (i+1)th inversion pulse signal from the last digit. The (i+1)th inversion pulse signal from the last digit is generated in at least the imaging area and the marking area.

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

[0093] In combination with the example above where N is 4, the range of action of the inversion pulse signal 1 may include the imaging area, the range of action of the inversion pulse signal 2 may include the marking area and the imaging area, the range of action of the inversion pulse signal 3 may include the imaging area, and the range of action of the inversion pulse signal 4 may include the marking area and the imaging area.

[0094] According to the above scheme of an embodiment of the present invention, the penultimate (i+1) inversion pulse signal can be used to perform the second inversion operation, thereby reducing the total amount of inversion pulse signals generated, which is beneficial to reducing the configuration cost of the host computer and the scanner, and improving the adaptability of magnetic resonance blood imaging to different scenarios.

[0095] Exemplarily, the length of the marking area 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 penultimate (i+1)th inversion pulse signal and the penultimate (i)th inversion pulse signal and the blood flow velocity of the blood to be imaged.

[0096] The background suppression region can be extended by a first value toward the source of the blood to be imaged to expand the effective range of the (i+1)th inversion pulse signal from the end. For example, if the blood velocity of the blood to be imaged is 0.03 cm / millisecond and the aforementioned time interval is 300 milliseconds, 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 utilize the (i+1)th inversion pulse signal from the end to pre-invert the net magnetization vector of the blood about to flow into the imaging region.

[0097] In practical scenarios, the blood to be imaged may 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 marking area may be lower than the first value of the second marking area. Specifically, the first value of the first marking area may be the product of the time interval between the penultimate (i+1) inversion pulse signal and the penultimate (i) inversion pulse signal and the blood flow velocity of the venous blood to be imaged. The first value of the second marking area may be the product of the time interval between the penultimate (i+1) inversion pulse signal and the penultimate (i) inversion pulse signal and the blood flow velocity of the arterial blood to be imaged.

[0098] It should be understood that the time interval between the i+1th inversion pulse signal from the end and the ith inversion pulse signal from the end may vary as i changes. In other words, the above-mentioned length of the marking area may be different for different inversion pulse signals. In conjunction with the example in which N is 4 above, the generation start time of the inversion pulse signal 4 may be approximately -1652.1 milliseconds, the generation start time of the inversion pulse signal 3 may be approximately -987.7 milliseconds, the generation start time of the inversion pulse signal 2 may be approximately -435.8 milliseconds, and the generation start time of the inversion pulse signal 1 may be approximately -107 milliseconds. The range of action of the inversion pulse signal 4 may include the background suppression area and the third marking area, and the range of action of the inversion pulse signal 2 may include the background suppression area and the fourth marking area. Since the time interval between the inversion pulse signal 4 and the inversion pulse signal 3 is greater than the time interval between the inversion pulse signal 2 and the inversion pulse signal 1, the above-mentioned length of the third marking area may be greater than the above-mentioned length of the fourth marking area.

[0099] According to the above-mentioned scheme of the embodiment of the present invention, on the one hand, the penultimate (i+1) inversion pulse signal can be used to perform the second inversion operation, thereby reducing the total amount of inversion pulse signals generated, which is beneficial to reducing the configuration cost of the host computer and scanner and improving the adaptability of magnetic resonance blood imaging for different scenarios. On the other hand, the range of action of the inversion pulse signal can be flexibly configured based on the blood flow velocity of the blood to be imaged. Not only can the blood to be imaged be fully inverted, effectively improving the imaging contrast of the blood to be imaged, but it also avoids excessive marking area and waste of resources.

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

[0101] The background suppression area includes the imaging area. The background suppression area and the imaging area have the same edge adjacent to the marking area. Figure 2 For an example in which the imaging region is the brain region, the lower edges of the background suppression region and the imaging region are the same edge, and this edge is adjacent to the marked region. For an example in which the imaging regions are the kidney region and the hip region, respectively, the upper edges of the background suppression region and the imaging region are the same edge, and this edge is adjacent to the marked region.

[0102] Reference again Figure 2 , in the horizontal direction, the position of the background suppression area coincides with the position of the imaging area. In the vertical direction, the length of the background suppression area is longer than the length of the imaging area. The layer-selected saturation pulse signal and the N inversion pulse signals are collectively referred to as target pulse signals. The second numerical value includes the product of the time interval between each two adjacent target pulse signals and the blood flow velocity of the blood to be suppressed. The blood to be suppressed may be blood that the user is not concerned about. For example, in the case where the user is concerned about the flow state of the arterial blood in the brain, the above-mentioned blood to be suppressed may include the venous blood in the brain. In 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 inversion pulse signal 1 and inversion pulse signal 2 and the blood flow velocity of the blood to be suppressed, the product of the time interval between inversion pulse signal 2 and inversion pulse signal 3 and the blood flow velocity of the blood to be suppressed, and so on. 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 of the second values. This ensures that the signals of all blood to be suppressed flowing into the imaging area are fully and effectively suppressed, preventing interference with the blood signal to be imaged.

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

[0104] According to the above-described solution of an embodiment of the present invention, a layer-selected saturation pulse signal and N inversion pulse signals can be sequentially generated within the background suppression region of the target object. The background suppression region includes the imaging region and other regions. Because the saturation pulse signal and the N inversion pulse signals have a larger range than the imaging region, background signal interference is reduced, the signal-to-noise ratio is improved, and the imaging contrast of the blood being imaged is enhanced. Furthermore, the background suppression region of the above-described size avoids artifacts in magnetic resonance images, and avoids excessive scanning times and unnecessary increases in computing resources.

[0105] Illustratively, step S130 , acquiring magnetic resonance signals of tissues in an imaging region 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 tissues are acquired in an imaging region based on a center-first sampling mode of the K space, and data filling is performed on the K space based on the acquired magnetic resonance signals.

[0107] K space can be used to store data of magnetic resonance images in the frequency domain. In magnetic resonance imaging, the collected data can be filled into the K space, and then the data in the frequency domain can be converted into data in the spatial domain (or image domain) to obtain a magnetic resonance image. The above-mentioned center-priority sampling mode can give priority to sampling the central area in the K space. The central area in the K space is usually related to the low-frequency component in the magnetic resonance image. The low-frequency component can represent the basic structural information of the tissue in the magnetic resonance image. Therefore, the use of the center-priority sampling mode helps to quickly generate magnetic resonance images that show the real physical differences between the imaged tissues. The above-mentioned central area may include multiple rows of space located in the middle of the K space. The specific number of rows can be determined by the developer or user based on actual needs, and the embodiment of the present invention does not limit this.

[0108] Each row of data in K-space can correspond to an encoding gradient. The host computer can send the encoding gradient to the gradient coils in the scanner to generate a gradient magnetic field. Magnetic resonance signals generated by this gradient magnetic field can be acquired and populated into the K-space corresponding to the encoding gradient. In this embodiment, magnetic resonance signals can be acquired preferentially based on the encoding gradient corresponding to the central region, achieving center-priority sampling.

[0109] refer to Figure 2In the K-space shown in the lower right corner, the data corresponding to the dark gray portion can be collected first, and then the data corresponding to the light gray portion can be collected. It can be understood that the data corresponding to the dark gray portion in the K-space is the data collected from time t1 to time t2, and the data corresponding to the light gray portion in the K-space is 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 processing to obtain a magnetic resonance image.

[0111] The data in K-space can be converted into data in the spatial domain through an inverse Fourier transform to obtain a magnetic resonance image. It should be understood that if K-space is two-dimensional, a two-dimensional magnetic resonance image can be obtained, and if K-space is three-dimensional, multiple two-dimensional magnetic resonance images can be obtained.

[0112] According to the above-described solution of an embodiment of the present invention, magnetic resonance signals of tissues in the imaging region can be acquired based on a center-priority sampling mode in K-space. Based on the acquired magnetic resonance signals, data is then filled in the K-space. Finally, the data in the filled K-space is subjected to an inverse Fourier transform to obtain a magnetic resonance image. Users are generally more interested in data in the central region of K-space. Therefore, the above-described solution utilizes a center-priority sampling mode to fill the K-space, which facilitates the rapid generation of magnetic resonance images that depict the true physical differences between the imaged tissues and better meets the actual needs of users.

[0113] Exemplarily, step S130 , acquiring magnetic resonance signals of tissues in the imaging region 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 encoding gradient, the following sub-steps 1 and 2 are performed until the data in each row of space corresponding to each target encoding gradient in the filled K-space is updated to obtain updated data. In sub-step 1, magnetic resonance signals are acquired in the imaging region based on the target encoding gradient. In sub-step 2, the data in the row of space corresponding to the target encoding gradient is updated.

[0115] The target encoding gradient is the phase encoding gradient corresponding to a preset region in K-space. The preset region can be determined by the developer or user based on actual needs and is not limited in this embodiment of the present invention. For example, the preset region can be the central region described above, or a portion of the central region.

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

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

[0118] Steps S133 to S135 are executed after step S132 is executed. Figure 2 , between time t3 and time t4, step S133 and step S134 are executed. As time goes by, due to the relaxation phenomenon of hydrogen atoms, the intensity of the signal generated by each tissue in the imaging area will gradually increase toward 1. It can be understood that the execution of step S131 and step S132 requires a certain amount of time ( Figure 2 (Time t1 to t3). When step S133 is executed, the signals of each tissue have substantially recovered to their initial signal strength. Therefore, the image obtained through steps S133 and S134 can be considered as a background image of the blood vessels in the imaging area.

[0119] Step S135 , fusing the magnetic resonance image with the background image to obtain a fused image.

[0120] The MRI image and background image can be superimposed and fused using preset coefficients. It should be understood that prior to fusion, one or both of the MRI image and background image can be processed using image processing operations. For example, these image processing operations may include image enhancement, brightness adjustment, filtering, image segmentation, etc. In one example, maximum projection processing can be performed on the MRI image to primarily highlight blood vessels. In other examples, the MRI image and / or background image can be processed using minimum projection, 3D segmentation reconstruction, and other methods.

[0121] According to the above-described solution of an embodiment of the present invention, data in the corresponding space in K-space can be updated for each target encoding gradient. The updated data is then subjected to an inverse Fourier transform to obtain a background image. Finally, the magnetic resonance image and the background image are fused to produce a fused image. In this solution, the magnetic resonance image primarily provides blood flow information, while the background image primarily provides background information. Therefore, the resulting fused image provides richer information for user analysis, facilitating qualitative research on the target object.

[0122] Exemplarily, the preset area may be a central area in the K space.

[0123] According to the above-described solution of an embodiment of the present invention, the central region of K-space is generally associated with low-frequency components in the image, which can represent basic structural information of the tissue in the image. Therefore, reacquiring data only in the central region can help quickly generate a background image that reflects the actual physical differences between the imaged tissues, thereby improving the overall efficiency of magnetic resonance imaging.

[0124] An embodiment of the present invention also provides a magnetic resonance blood imaging device. Figure 8 FIG2 shows a schematic block diagram of a magnetic resonance blood imaging device 200 according to an embodiment of the present invention. Figure 8 As shown, the magnetic resonance blood imaging apparatus 200 includes a processor 210 and an execution device 220. The processor 210 is configured to control the execution device 220 to perform the following steps: generating a slice-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 tissue in at least the imaging region. After or simultaneously with the first inversion operation on the blood in the imaging region using the reciprocal (i+1)th inversion pulse signal of the N inversion pulse signals, and before the first inversion operation on the blood in the imaging region using the reciprocal (i)th inversion pulse signal of the N inversion pulse signals, a second inversion operation is performed on the blood in the marking region of the target object. i is a positive odd number less than N, the marking region is adjacent to the imaging region, and the blood to be imaged flows into the imaging region via the marking region. 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 execution device 220 may include a scanner. The scanner is used to apply a main magnetic field, a radio frequency pulse signal, and acquire magnetic resonance signals. The specific functions of the scanner can be found in the description of step S110.

[0126] Exemplarily, 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 execute: only between the end time of generation of the penultimate (i+1) inversion pulse signal and the start time of generation of the penultimate (i) inversion pulse signal, generate another inversion pulse signal in the marked area of the target object to perform a second inversion operation on the blood in the marked area.

[0127] Exemplarily, another inversion pulse signal is generated at the end time of generation of the (i+1)th inversion pulse signal from the last and continues until the start time of generation of the (i)th inversion pulse signal from the last.

[0128] Exemplarily, the additional inversion pulse signal is an arterial spin labeling pulse signal, wherein the arterial spin labeling pulse signal is used to perform arterial spin labeling on blood in the labeling region.

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

[0130] Exemplarily, 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: performing a second inversion operation on the blood in the marked area using the penultimate (i+1)th inversion pulse signal, wherein the penultimate (i+1)th inversion pulse signal is generated in at least the imaging area and the marking area.

[0131] Exemplarily, the length of the marking area 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 penultimate (i+1)th inversion pulse signal and the penultimate (i)th inversion pulse signal and the blood flow velocity of the blood to be imaged.

[0132] Exemplarily, the processor 210 controls the execution device 220 to execute generating a layer-selected saturation pulse signal in at least the imaging area of the target object, and is further configured to control the execution device 220 to execute: generating a layer-selected saturation pulse signal in the background suppression area of the target object, wherein the background suppression area includes the imaging area, the background suppression area and the imaging area have the same edge adjacent to the marking area, and in the flow direction of the blood to be imaged, the length of the background suppression area is greater than or equal to the maximum value of the second value, the second value includes the time interval between each two adjacent target pulse signals and the product of the blood flow velocity of the blood to be suppressed, and the target pulse signal includes the layer-selected saturation pulse signal and N inversion pulse signals.

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

[0134] Exemplarily, the processor 210 controls the 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. The processor 210 is further configured to control the execution device 220 to acquire magnetic resonance signals of tissue in the imaging region based on a center-first sampling mode of K-space, perform data filling on the K-space based on the acquired magnetic resonance signals, and perform inverse Fourier transform processing on the data in the filled K-space to obtain a magnetic resonance image.

[0135] Exemplarily, the processor 210 controls the 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. The processor 210 is further configured to control the execution device 220 to execute: for each target encoding gradient, execute the following sub-steps 1 and 2 until the data in a row of space corresponding to each target encoding gradient in the filled K space is updated to obtain updated data. The target encoding gradient is a phase encoding gradient corresponding to a preset region in the K space. Sub-step 1: Based on the target encoding gradient, acquire magnetic resonance signals in the imaging region. Sub-step 2: Update the data in a row of space corresponding to the target encoding gradient. Perform inverse Fourier transform processing on the updated data to obtain a background image. Fuse the magnetic resonance image with the background image to obtain a fused image.

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

[0137] In addition, 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 is caused to perform the corresponding steps of the magnetic resonance blood imaging method according to the embodiment of the present invention, and is used to implement the corresponding modules in the magnetic resonance blood imaging device according to the embodiment of the present invention. The non-volatile storage medium may include, for example, 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 disk 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 provided, comprising computer program instructions. When executed by a processor, the computer program instructions cause the processor to perform the corresponding steps of the magnetic resonance blood imaging method. A person skilled in the art will understand the specific implementation of the apparatus, non-volatile storage medium, and computer program product described above after reading the above description of the magnetic resonance blood imaging method. For the sake of brevity, these details are not further described here.

[0139] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely illustrative and are not intended to limit the scope of the present invention. Various changes and modifications may be made therein by those skilled in the art without departing from the scope and spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as claimed in the appended claims.

[0140] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0141] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units described is merely a logical functional division. In actual implementation, other division methods may be used. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not implemented.

[0142] In the description provided herein, numerous specific details are described. However, it is understood that embodiments of the present invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0143] Similarly, it should be understood that in order to streamline the present invention and aid in understanding one or more of the various inventive aspects, in the description of exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this approach to the present invention should not be interpreted as reflecting the intention that the claimed invention requires more features than those explicitly recited in each claim. More precisely, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with fewer features than all the features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into the detailed description, with each claim itself serving as a separate embodiment of the present invention.

[0144] It will be understood by those skilled in the art that, except where mutually exclusive, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or apparatus disclosed herein may be combined in any combination. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature providing the same, equivalent, or similar purpose.

[0145] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of the present invention and to form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

[0146] The various component embodiments of the present invention can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art will appreciate that a microprocessor or digital signal processor (DSP) can be used in practice to implement some or all of the functions of some modules in a magnetic resonance blood imaging device according to an embodiment of the present invention. The present invention can also be implemented as a device program (e.g., a computer program and a computer program product) for executing part or all of the methods described herein. Such a program for implementing the present invention can be stored on a computer-readable medium, or can be in the form of one or more signals. Such a signal can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0147] It should be noted that the above embodiments illustrate rather than limit the invention, and that those skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between brackets should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present invention may be implemented by means of hardware comprising several different elements and by means of suitably programmed computers. In a unit claim 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 may be interpreted as names.

[0148] The foregoing description is merely a specific embodiment of the present invention or an illustration of a specific embodiment. The scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed in the present invention are intended to be encompassed by the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A magnetic resonance blood imaging method, characterized in that: The method comprises: generating a slice-selective saturation pulse signal in at least an imaging region of the target object; sequentially generating N inversion pulse signals in at least the imaging region to perform a first inversion operation on tissue in at least the imaging region, wherein after or simultaneously with performing the first inversion operation on the tissue in at least the imaging region using the reciprocal (i+1)th inversion pulse signal among the N inversion pulse signals and before performing the first inversion operation on the tissue in at least the imaging region using the reciprocal (i)th inversion pulse signal among the N inversion pulse signals, a second inversion operation is performed on blood in a marking region of the target object, where i is a positive odd number less than N, the marking region is adjacent to the imaging region and the blood to be imaged flows into the imaging region via the marking region; 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 according to claim 1, wherein The performing a second inversion operation on the blood in the marked area of the target object includes: Only between the end time of the generation of the (i+1)th inversion pulse signal from the last and the start time of the generation of the (i)th inversion pulse signal from the last, another inversion pulse signal is generated in the marked area of the target object to perform a second inversion operation on the blood in the marked area.

3. The method according to claim 2, wherein The other inversion pulse signal is generated at the time when the generation of the (i+1)th inversion pulse signal from the last is finished and continues until the time when the generation of the (i)th inversion pulse signal from the last is started.

4. The method according to claim 2, wherein The additional inversion pulse signal is an arterial spin labeling pulse signal, wherein the arterial spin labeling pulse signal is used to perform arterial spin labeling on the blood in the labeling region.

5. The method according to claim 4, wherein The arterial spin labeling includes any one of the following: continuous arterial spin labeling and pseudo-continuous arterial spin labeling.

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

7. The method according to claim 6, wherein The length of the marking area 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 penultimate (i+1)th inversion pulse signal and the penultimate (i)th inversion pulse signal and the blood flow velocity of the blood to be imaged.

8. The method according to claim 1, wherein Generating a slice-selective saturation pulse signal in at least an imaging region of the target object comprises: generating a slice-selected saturation pulse signal in a 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 marking region, and in the flow direction of the blood to be imaged, a length of the background suppression region is greater than or equal to a maximum value of second values, the second value including a product of a time interval between every two adjacent target pulse signals and a blood flow velocity of the blood to be suppressed, and the target pulse signal includes the slice-selected saturation pulse signal and the N inversion pulse signals; Sequentially generating N inversion pulse signals in at least the imaging region to perform a first inversion operation on tissue in at least the imaging region, comprising: N inversion pulse signals are sequentially generated 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 acquiring magnetic resonance signals of tissue in the imaging region and generating a magnetic resonance image based on the acquired magnetic resonance signals includes: Based on a center-first sampling mode of K space, magnetic resonance signals of tissue are acquired in the imaging region, and data filling is performed on the K space based on the acquired magnetic resonance signals; The data in the filled K space is subjected to inverse Fourier transform processing to obtain a magnetic resonance image.

10. The method according to claim 9, wherein The 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 encoding gradient, the following steps are performed until the data in a row of space corresponding to each target encoding gradient in the filled K space is updated to obtain updated data, wherein the target encoding gradient is a phase encoding gradient corresponding to a preset area in the K space: acquiring magnetic resonance signals in the imaging region based on the target encoding gradient; Update the data in a row of space corresponding to the target encoding gradient; Performing inverse Fourier transform processing on the updated data to obtain a background image; The magnetic resonance image is fused with the background image to obtain a fused image.

11. The method according to claim 10, wherein 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, wherein the processor is configured to control the execution device to perform the following steps: generating a slice-selective saturation pulse signal in at least an imaging region of the target object; sequentially generating N inversion pulse signals in at least the imaging region to perform a first inversion operation on tissue in at least the imaging region, wherein after or simultaneously with performing the first inversion operation on the tissue in at least the imaging region using the reciprocal (i+1)th inversion pulse signal among the N inversion pulse signals and before performing the first inversion operation on the tissue in at least the imaging region using the reciprocal (i)th inversion pulse signal among the N inversion pulse signals, a second inversion operation is performed on blood in a marking region of the target object, where i is a positive odd number less than N, the marking region is adjacent to the imaging region and the blood to be imaged flows into the imaging region via the marking region; 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: When the computer program instructions are executed by a processor, the computer program instructions are used to perform the magnetic resonance blood imaging method according to any one of claims 1 to 11.

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

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