A one-stop multi-delay arterial spin labeling kidney perfusion measurement method and system

Abstract

The application provides a one-stop multi-delay arterial spin labeling kidney perfusion measurement method and system, and belongs to the field of magnetic resonance imaging. The method comprises the following steps: acquiring a time-encoding-based kidney arterial spin labeling sequence image of a subject; acquiring a kidney M0 image of the subject, wherein the M0 image is consistent with the number of layers, resolution and image acquisition mode of the kidney arterial spin labeling sequence image; and performing registration on the kidney arterial spin labeling sequence image and the M0 image to obtain a kidney perfusion measurement result of the subject. The application can realize one-stop multi-delay blood perfusion quantitative imaging of the kidney, greatly improves the imaging efficiency of traditional kidney multi-delay arterial spin labeling imaging, and fills the blank of one-stop multi-delay blood perfusion imaging of the kidney.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of magnetic resonance imaging, and particularly relates to a one-stop multi-delay arterial spin labeling kidney perfusion measurement method and system. BACKGROUND

[0002] The kidney is one of the main organs of the human body and is the main regulator of the body's balance, having important physiological functions such as maintaining normal body fluid composition, excreting external and metabolic waste, regulating blood pressure, and generating hormones. Chronic or acute damage to the kidney can lead to a series of serious complications such as anemia, hypertension, heart failure, acid-base imbalance, digestive diseases, mineral bone metabolism abnormalities, hyperparathyroidism, and central nervous system disorders, significantly reducing the quality of life of patients and even endangering the lives of patients.

[0003] Narrowing of the renal artery and adjacent abdominal aorta and other large arteries, renal microvascular dysfunction, hypotension, hemorrhage, and reduced cardiac output can all lead to reduced kidney perfusion, which in turn leads to acute or chronic ischemia of the kidney, causing damage to kidney function. Currently, kidney perfusion has become the main alternative indicator of kidney function in addition to glomerular filtration rate (GFR) in clinical practice. Common traditional kidney tissue perfusion quantification imaging methods include dynamic contrast-enhanced computed tomography (DCE-CT) technology and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) technology. However, since such dynamic contrast-enhanced techniques require the injection of a contrast agent that is toxic to the kidneys, their application to patients with renal dysfunction has certain limitations, and most related examinations use low-dose contrast agents or arrange post-examination dialysis to reduce the associated risks. Positron emission tomography (PET) can evaluate kidney perfusion by tracking positron-emitting nuclide-labeled blood, but PET imaging is relatively expensive and is still difficult to become a routine clinical examination method, and patients are also harmed by ionizing radiation.

[0004] Unlike traditional kidney perfusion evaluation methods such as DCE-CT, DCE-MRI, and PET, which require the injection of a contrast agent, magnetic resonance arterial spin labeling (ASL) technology uses the magnetization of water in arterial blood as an endogenous tracer, eliminating the need for the injection of a contrast agent and reducing the burden of examination on patients with renal dysfunction.

[0005] However, there are still many problems and challenges in ASL (Advanced Perfusion Sampling) for the kidneys. To achieve contrast-free perfusion measurement, ASL technology requires using radiofrequency pulses to magnetize and label hydrogen atoms in the blood. Labeled and control images are acquired after labeled and unlabeled blood flows into the target organ, respectively. Subtracting the two images yields the perfusion-weighted ASL signal. By fitting the ASL signal using an ASL kinetic model, the specific perfusion value of the target organ can be obtained. The ASL signal in each voxel changes with the post-labeling delay time (PLD). In ASL studies, the setting of PLD is crucial. A longer PLD allows a larger volume of labeled blood to be delivered to the target organ, but at the cost of ASL signal loss due to T1 decay. Therefore, the optimal PLD setting point should be near the peak of the ASL signal change curve, i.e., near the labeled blood arrival time (BAT). Compared to the brain, the kidney BAT is more affected by age, individual differences, and various pathological factors, and the range of PLD selection reported in related kidney ASL studies is extremely wide (0.9–2.3 s). Therefore, the application of single-delay time ASL technology, commonly used in cranial examinations, to the kidneys has significant limitations due to the inability to determine a suitable PLD. Traditional multi-delay time ASL requires repeated scanning of the single-delay time ASL sequence, resulting in long imaging times and cumbersome operation, making it difficult to apply clinically. Currently, there is no time-coding-based one-stop multi-delay renal artery spin labeling technology. Summary of the Invention

[0006] The purpose of this invention is to fill the gap in existing technologies by proposing a one-stop, multi-delay arterial spin labeling method and system for measuring renal perfusion. This invention enables one-stop, multi-delay renal perfusion quantitative imaging of the kidney, reducing imaging time, improving imaging efficiency, and filling the gap in one-stop, multi-delay arterial spin labeling technology for the kidney.

[0007] A first aspect of this invention provides a one-stop, multi-delay arterial spin labeling method for measuring renal perfusion, comprising:

[0008] Acquire time-coded renal artery spin label sequence images of the subjects;

[0009] The subject's kidney M0 image was acquired, and the M0 image was consistent with the renal artery spin labeling sequence image in terms of layer number, resolution, and image acquisition mode.

[0010] The renal perfusion measurement results of the subject were obtained by registering the renal artery spin label sequence image and the M0 image.

[0011] In one specific embodiment of the present invention, the time-coded renal artery spin labeling sequence image is obtained by setting a renal artery spin labeling sequence on a magnetic resonance scanner;

[0012] The renal artery spin labeling sequence consists of N cycles, where N ≥ 4 and is an integer multiple of 4; each cycle includes: a pre-saturation pulse phase, an artery spin labeling phase, a post-labeling delay phase, and a data acquisition phase;

[0013] The pre-saturation pulse stage uses a single saturation pulse or a combination of saturation pulses to zero out the signal at the imaging plane before the arterial spin labeling stage, thereby eliminating errors caused by incomplete relaxation.

[0014] The arterial spin labeling element is used to transmit radio frequency pulses according to a set code in order to label the blood flowing through the kidneys of the subject.

[0015] The post-labeling delay step is used to wait for the labeled blood to flow from the labeled layer into the subject's kidneys;

[0016] The data acquisition step is used to acquire images of the subject's kidneys.

[0017] In a specific embodiment of the present invention, the arterial spin labeling link is a combination of N-1 label blocks and control blocks, wherein the blood signal is labeled when the label blocks are in use, and the blood signal is kept unchanged when the control blocks are in use; both the label blocks and the control blocks are composed of continuous small-angle radio frequency pulses and gradients, such that the ideal cumulative phase of the label blocks is 2π and the ideal cumulative phase of the control blocks is 0; the radio frequency pulses are transmitted according to a preset time coding matrix, the size of which is N*(N-1).

[0018] In a specific embodiment of the present invention, the method for constructing the time encoding matrix is ​​as follows:

[0019] An N-order square matrix formed by N cycles of arterial spin labeling is encoded to obtain an initial encoding matrix of size N*N. In the initial encoding matrix, the label block is marked as +1 and the control block is marked as -1. The initial encoding matrix Hn satisfies Hn*Hn'=NI, where Hn' is the transpose of Hn and I is the identity matrix. The column in the initial encoding matrix that is all +1 is deleted to obtain a time encoding matrix of size (N-1)*N.

[0020] In one specific embodiment of the present invention, prior to acquiring time-coded renal artery spin label sequence images of the subject, the method further includes:

[0021] The renal artery spin labeling sequence was localized to determine its position within the imaging frame of the subject's abdomen.

[0022] In one specific embodiment of the present invention, prior to acquiring the kidney M0 image of the subject, the method further includes:

[0023] The acquisition sequence of the M0 image is localized, and the localization result of the acquisition sequence of the M0 image is consistent with the localization result of the renal artery spin labeling sequence.

[0024] In one specific embodiment of the present invention, the step of registering the renal artery spin label sequence image and the M0 image to obtain the renal perfusion measurement results of the subject includes:

[0025] 1) Using a non-rigid group registration algorithm, the renal artery spin label sequence images are registered layer by layer to obtain the pre-registered renal artery spin label sequence images, wherein the number of renal artery spin label sequence images = N × average number of times × number of layers, and the average number of times is the number of times the renal artery spin label sequence is completed when acquiring the renal artery spin label sequence images;

[0026] 2) Using a non-rigid or rigid registration algorithm, the renal artery spin label sequence image obtained after the preliminary registration in step 1) is registered with the M0 image layer by layer to obtain the final registered renal artery spin label sequence image;

[0027] 3) Based on the final encoding matrix, the renal artery spin label sequence image after final registration is decoded and averaged to obtain renal perfusion weighted images at different delay times. The number of renal perfusion weighted images is (N-1) × number of layers.

[0028] 4) Using a kinetic model targeting arterial spin labels, the renal perfusion weighted images obtained in step 3) at different delay times are fitted to obtain a quantitative map of renal blood flow perfusion and a quantitative map of arterial transit time, which are the renal perfusion measurement results of the subject.

[0029] A second aspect of the present invention provides a one-stop multi-delay arterial spin labeling renal perfusion measurement device, comprising:

[0030] A renal artery spin labeling sequence image acquisition module is used to acquire time-coded renal artery spin labeling sequence images of the subject;

[0031] The M0 image acquisition module is used to acquire the kidney M0 image of the subject. The M0 image is consistent with the number of layers, resolution and image acquisition mode of the renal artery spin labeling sequence image.

[0032] The post-processing module is used to obtain the renal perfusion measurement results of the subject by registering the renal artery spin label sequence image and the M0 image.

[0033] A third aspect of the present invention provides an electronic device comprising:

[0034] At least one processor; and a memory communicatively connected to said at least one processor;

[0035] The memory stores instructions that can be executed by the at least one processor, and the instructions are configured to perform the above-described one-stop multi-delay arterial spin labeling renal perfusion measurement method.

[0036] A fourth aspect of the present invention provides a computer-readable storage medium storing computer instructions for causing the computer to execute the above-described one-stop multi-delay arterial spin labeling renal perfusion measurement method.

[0037] Features and beneficial effects of the present invention:

[0038] Traditional multi-delay arterial labeling techniques for the kidneys require multiple repeated single-delay arterial labeling scans, resulting in excessively long scanning times and complex procedures. This invention employs time-coded arterial spin labeling technology to achieve one-stop acquisition of multi-delay renal perfusion images. Post-processing steps, such as retrospective registration, enable multi-delay renal perfusion metrology, significantly reducing imaging time and improving imaging efficiency compared to traditional techniques. This invention makes multi-delay renal perfusion metrology imaging potentially applicable to routine clinical diagnosis and evaluation of kidney diseases, filling the gap in one-stop multi-delay arterial spin labeling technology for the kidneys. Attached Figure Description

[0039] Figure 1 This is an overall flowchart of a one-stop multi-delay arterial spin labeling method for measuring renal perfusion according to an embodiment of the present invention.

[0040] Figure 2 This is a time-coded renal artery spin label (TASK) sequence design diagram in a specific embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram of the location of the TASK sequence in a specific embodiment of the present invention.

[0042] Figure 4This is a flowchart illustrating how, in a specific embodiment of the present invention, renal perfusion measurement results are obtained by registering TASK sequence images and M0 images.

[0043] Figure 5 This is a specific embodiment of the present invention applied to the quantitative map of renal blood perfusion and the quantitative map of arterial transit time obtained in healthy individuals.

[0044] Figure 6 This invention provides a specific embodiment of renal artery magnetic resonance angiography, renal artery wall imaging, renal blood flow perfusion quantification, and arterial transit time quantification for patients with renal artery stenosis.

[0045] Figure 7 This is a specific embodiment of the present invention applied to the renal blood perfusion quantification map and arterial transit time quantification map obtained in patients with diabetic nephropathy. Detailed Implementation

[0046] This invention proposes a one-stop multi-delay arterial spin labeling method and system for measuring renal perfusion, which is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] A first aspect of this invention provides a one-stop, multi-delay arterial spin labeling method for measuring renal perfusion, comprising:

[0048] Acquire time-coded renal artery spin label sequence images of the subjects;

[0049] The subject's kidney M0 image was acquired, and the M0 image was consistent with the renal artery spin labeling sequence image in terms of layer number, resolution, and image acquisition mode.

[0050] The renal perfusion measurement results of the subject were obtained by registering the renal artery spin label sequence image and the M0 image.

[0051] In a specific embodiment of the present invention, the overall process of the one-stop multi-delay arterial spin labeling renal perfusion measurement method is as follows: Figure 1 As shown, it includes the following steps:

[0052] 1) Raw images of the subject’s renal perfusion were obtained by setting up a time-coded renal artery spin label (TASK) sequence on a magnetic resonance scanner.

[0053] In one specific embodiment of the present invention, the design diagram of the renal artery spin labeling sequence is as follows: Figure 2As shown, the sequence consists of N cycles (N = 4, 8, 12..., N ≥ 4 and N is an integer multiple of 4). Each cycle includes: a pre-saturation pulse stage, an arterial spin labeling (ASL) stage based on pseudo-continuous arterial spin labeling (pCASL) technology, a post-labeling delay (PLD) stage, and a data acquisition stage.

[0054] It should be noted that in actual clinical use, the arterial spin labeling signal may be very weak. Therefore, it is usually necessary to acquire multiple sets of renal artery spin labeling sequences consisting of N cycles and then average them to achieve a higher signal-to-noise ratio in the perfusion images. Typically, it is necessary to ensure that at least 40 images per slice are acquired. For example, if the number of cycles N = 8, then at least 5 sets of N cycles should be acquired and averaged, i.e., the average number of times should be 5.

[0055] In one specific embodiment of the present invention, such as Figure 2 As shown, N = 8. In each cycle, the pre-saturation pulse stage can use a single saturation pulse (e.g., a 90° radio frequency pulse) or a combination of saturation pulses (e.g., T1-effect enhanced water suppression WET) to zero the signal across the entire imaging plane before the arterial spin labeling stage, thereby eliminating errors caused by incomplete relaxation. Within the same sequence, the saturation pulse used in the pre-saturation stage remains constant for each cycle. In one specific embodiment of the invention, the pre-saturation pulse stage uses a combination of saturation pulses (WET).

[0056] Each ASL (Arterial Spin Marking) stage in a cycle is a combination of (N-1) marker blocks and control blocks. The marker blocks mark the blood signal (i.e., progressively flipping the blood signal to 180°); the control blocks keep the blood signal unchanged, serving as a reference for marking the blood. Both the marker blocks and control blocks consist of continuous small-angle radio frequency pulses and gradients, ensuring that the ideal cumulative phase of the marker blocks is 2π, while the ideal cumulative phase of the control blocks is 0. The radio frequency pulses are transmitted according to a preset time-coding matrix. In this embodiment, the time-coding matrix is ​​constructed as follows: an N*N initial encoding matrix is ​​obtained by encoding an N-order square matrix formed by N cycles of arterial spin marking stages. In this initial encoding matrix, marker blocks are denoted as "+1", control blocks as "-1", and the initial encoding matrix Hn must satisfy Hn*Hn' = NI, where Hn' is the transpose of Hn, and NI is the identity matrix. In this N*N coding matrix, there must be a column consisting entirely of "+1" (i.e., a column consisting entirely of marker blocks, usually the first column of the matrix). This column is removed, resulting in an (N-1)*N time coding matrix. The coding matrix includes, but is not limited to, the Hadamard matrix and the Walsh-Hadamard matrix.Figure 2 The Walsh-Hadamard matrix is ​​used for encoding. After the encoding is set up, markers or control radio frequency pulses are emitted according to the corresponding codes to mark the subject's blood. It should be noted that, depending on the specific encoding of the matrix, a row may consist entirely of marker blocks or control blocks. (The last sentence appears to be incomplete and possibly refers to a different process.) Figure 2 In the illustrated embodiment, the first row consists entirely of marker blocks. However, typically one row consists entirely of marker blocks, and it is rare for an entire row to consist entirely of control blocks.

[0057] In the post-labeling delay phase, no radiofrequency pulses or gradients are applied. This phase allows the blood awaiting labeling to flow from the labeled layer into the target organ, namely the kidney.

[0058] The data acquisition stage is used to acquire images of the subject's kidneys. This stage can acquire abdominal imaging data through various magnetic resonance data acquisition modes such as two-dimensional, multi-layer two-dimensional, and three-dimensional. Each cycle completes the acquisition of one image (using the two-dimensional acquisition method) or a set of multi-layer images (using the multi-layer two-dimensional or three-dimensional acquisition method).

[0059] In this embodiment, during magnetic resonance imaging (MRI) scanning, the subject is guided into the MRI scanner with the trunk coil already connected. The subject lies face up, head pointing towards the magnet, on the MRI scanner bed. The trunk coil is placed over the subject's chest and abdomen, completely covering the abdomen. The MRI scanner bed is moved so that the infrared positioning center in the MRI scanner is located at the center of the subject's diaphragm. The MRI scanner is used to perform a positioning scan on the subject's abdomen. A conventional positioning sequence can be used to determine the location of the subject's bilateral kidneys and abdominal aorta. Then, the TASK sequence of this embodiment is positioned on the interactive interface of the MRI scanning platform. A positioning diagram of a specific embodiment of this invention is shown below. Figure 3 As shown, where, Figure 3 The white rectangular frames in the three images are all photo frames. Figure 3 The three images from left to right are schematic diagrams of the same frame viewed from three different perspectives: coronal, axial, and sagittal. The positioning images were obtained by scanning according to a conventional positioning sequence, where, as in... Figure 3 The coronal view of the localization image shown in the left-hand image and Figure 3 The positions of the imaging frames are determined on the axial views shown in the intermediate images. Imaging is mostly coronal scanning. If it is a two-dimensional single-slice imaging, the axial view is placed in the central layer of both kidneys, and the coronal view includes both kidneys with the kidneys centered in the imaging field of view. If it is a multi-slice or three-dimensional sequence, the axial view covers both kidneys (multi-slice is approximately 7-10 layers, which may vary depending on the resolution), and the coronal view includes both kidneys with the kidneys centered in the imaging field of view. The marker bands (i.e.,...) are then used to define the imaging frames.Figure 3 The white shaded horizontal bar in the left image is positioned above both kidneys in the coronal plane, with its center at the abdominal aorta. Confirm the marker band in the coronal plane. Figure 3 (left image) and sagittal ( Figure 3 Place the marker parallel to the right side of the image, with the center of the marker about 10cm from the center of both kidneys.

[0060] This embodiment uses a method for renal perfusion imaging. A resolution of 3-5 mm within an imaging slice and 5-10 mm between slices are recommended. These can be adjusted as needed, but it should be noted that higher resolution results in longer scan times and may reduce the signal-to-noise ratio. The durations of the arterial spin labeling stage and the post-labeling delay stage, as well as the duration allocation of each labeling block and control block, are relatively flexible. Table 1 lists several commonly used duration allocations for a single cycle in a specific embodiment of this invention using a 7×8 coding matrix for the arterial spin labeling stage. This parameter enables time-coded quantitative imaging of renal perfusion. It should be noted that the duration allocation for each cycle remains consistent within the same sequence.

[0061] Table 1. A table showing the commonly used duration allocation of a single cycle in a specific embodiment of the present invention using a 7×8 encoding matrix for the arterial spin labeling step.

[0062]

[0063] 2) Obtain the M0 image of the subject's kidney.

[0064] The M0 acquisition sequence is set for image post-processing. In this embodiment, this sequence is a standard proton density-weighted image (PDW). The number of image layers, resolution, and data acquisition mode must be consistent with the TASK sequence in step 1), but there is no need to add the pre-saturation pulse step, arterial spin labeling step, and post-labeling delay step. The M0 image can be acquired before or after the TASK sequence (only once), and the positioning must be consistent with the TASK sequence, but there is no need to place a label band.

[0065] 3) Renal perfusion measurement results were obtained by registering time-coded renal artery spin label sequence images and M0 images.

[0066] In this embodiment, the images acquired through the TASK sequence and the M0 image are registered layer by layer. The number of images acquired through the TASK sequence = N × average number of iterations × number of layers, where the average number of iterations is the number of times N cycles are completed. Kidney perfusion measurement is then performed based on the registered images. The overall process of this step in this embodiment is as follows: Figure 4 As shown, the specific steps are as follows:

[0067] 3-1) Using a non-rigid group registration algorithm, all images obtained from the TASK sequence are registered by plane to obtain pre-registered TASK sequence images. In a specific embodiment of the present invention, a group registration algorithm based on principal component analysis (PCA) is used.

[0068] 3-2) Using a non-rigid or rigid registration algorithm, the TASK sequence image obtained after the preliminary registration in step 3-1) is registered with the M0 image by layer to obtain the final registered TASK sequence image. In a specific embodiment of the present invention, a non-rigid registration method based on mutual information is adopted.

[0069] 3-3) Based on the time encoding matrix in step 1), the final registered TASK sequence images (number of N × average number of times × number of layers) obtained in step 3-2) are decoded and averaged to obtain renal perfusion weighted images (number of (N-1) × number of layers) under different delay times;

[0070] 3-4) Using a kinetic model targeting arterial spin labels, quantitative renal blood flow perfusion (RBF) and arterial transit time (ATT) maps are obtained by fitting the renal perfusion weighted images at different delay times obtained in step 3-3). The kinetic model includes, but is not limited to, the classic single-compartment model or the dual-compartment model. In a specific embodiment of the present invention, the classic single-compartment Buxton model is used.

[0071] In a specific embodiment of the present invention, the quantitative RBF map and ATT map of healthy individuals obtained by the method are as follows: Figure 5 As shown. Figure 5 The upward image is a quantitative RBF map of a healthy person from two different layers (the two on the left are the same layer, and the two on the right are the same layer. In this example, seven layers of coronal images of the kidney were acquired, and two layers were selected as examples). The downward image is a quantitative ATT map of a healthy person from the corresponding two layers.

[0072] Figure 6 This is a schematic diagram illustrating the results obtained from a specific embodiment of the present invention applied to a 49-year-old male patient with left renal artery stenosis. The results were obtained through renal artery magnetic resonance angiography. Figure 6 (A) Obvious narrowing can be seen at the opening of the left renal artery, and imaging can be performed through the renal artery wall. Figure 6 (B) It can be seen that the wall of the left renal artery is significantly thickened and the lumen is narrowed at the stenosis site. Quantitative RBF maps are obtained using this invention. Figure 6 (C) and ATT quantitative chart Figure 6 (D) It can be seen that the RBF of the affected kidney (left side) in this patient is decreased, while the ATT is increased. This demonstrates the feasibility of the present invention for detecting renal blood perfusion status.

[0073] Figure 7 In a specific embodiment of the present invention, the RBF quantitative map and ATT map were obtained from a 65-year-old male patient with diabetic nephropathy, wherein... Figure 7 (A) is the RBF quantitative graph of this patient. Figure 7 (B) is the ATT quantitative map of the patient. The RBF of the patient's kidney was significantly reduced and the ATT was significantly increased, indicating that the patient's renal blood perfusion was reduced and the blood perfusion rate was slowed down, which shows that the present invention is feasible for detecting the renal blood perfusion status.

[0074] To achieve the above embodiments, a second aspect of the present invention provides a one-stop multi-delay arterial spin labeling renal perfusion measurement device, comprising:

[0075] A renal artery spin labeling sequence image acquisition module is used to acquire time-coded renal artery spin labeling sequence images of the subject;

[0076] The M0 image acquisition module is used to acquire the kidney M0 image of the subject. The M0 image is consistent with the number of layers, resolution and image acquisition mode of the renal artery spin labeling sequence image.

[0077] The post-processing module is used to obtain the renal perfusion quantitative measurement results of the subject by registering the renal artery spin label sequence image and the M0 image.

[0078] It should be noted that the foregoing explanation of the embodiment of a one-stop multi-delay arterial spin labeling renal perfusion measurement method also applies to the one-stop multi-delay arterial spin labeling renal perfusion measurement device of this embodiment, and will not be repeated here. According to the embodiments of the present invention, a one-stop multi-delay arterial spin labeling renal perfusion measurement device acquires a time-coded renal artery spin labeling sequence image of a subject; acquires a kidney M0 image of the subject, wherein the M0 image and the renal artery spin labeling sequence image have the same layer number, resolution, and image acquisition mode; and obtains the renal perfusion measurement result of the subject by registering the renal artery spin labeling sequence image and the M0 image. This enables one-stop multi-delay renal perfusion quantitative imaging of the kidney, reducing imaging time, improving imaging efficiency, and filling the gap in one-stop multi-delay arterial spin labeling technology for the kidney. To implement the above embodiments, a third aspect of the present invention proposes an electronic device, comprising:

[0079] At least one processor; and a memory communicatively connected to said at least one processor;

[0080] The memory stores instructions that can be executed by the at least one processor, and the instructions are configured to perform the above-described one-stop multi-delay arterial spin labeling renal perfusion measurement method.

[0081] To implement the above embodiments, a fourth aspect of the present invention provides a computer-readable storage medium storing computer instructions for causing the computer to execute the above-described one-stop multi-delay arterial spin labeling renal perfusion measurement method.

[0082] It should be noted that the computer-readable medium described in this disclosure can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this disclosure, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in connection with an instruction execution system, apparatus, or device. In this disclosure, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (radio frequency), etc., or any suitable combination thereof.

[0083] The aforementioned computer-readable medium may be included in the aforementioned electronic device; or it may exist independently and not assembled into the electronic device. The aforementioned computer-readable medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to perform a one-stop multi-delay arterial spin labeling renal perfusion measurement method according to the above embodiments.

[0084] Computer program code for performing the operations of this disclosure can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0085] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0086] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0087] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0088] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0089] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0090] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0091] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0092] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A one-stop multi-delay arterial spin labeling renal perfusion measurement method, characterized in that, The method comprises the following steps: acquiring a time-encoding based renal arterial spin labeling sequence image of a subject; acquiring a renal M0 image of the subject, which is consistent with the renal arterial spin labeling sequence image in terms of number of layers, resolution and image acquisition mode; obtaining a renal perfusion measurement result of the subject by registering the renal arterial spin labeling sequence image and the M0 image; wherein the time-encoding based renal arterial spin labeling sequence image is acquired by setting a renal arterial spin labeling sequence on a magnetic resonance scanner; the renal arterial spin labeling sequence comprises N cycles, N≥4 and is an integer multiple of 4; each cycle comprises a presaturation pulse link, an arterial spin labeling link, a post-labeling delay link and a data acquisition link; the arterial spin labeling link is used to emit a radio frequency pulse according to a set encoding to label blood flowing through the kidney of the subject; the arterial spin labeling link is a combination of N-1 labeling blocks and a control block, wherein blood signal is labeled in the labeling block and kept unchanged in the control block; the labeling block and the control block are both composed of continuous small-angle radio frequency pulses and gradients, so that the ideal cumulative phase of the labeling block is 2π and the ideal cumulative phase of the control block is 0; the radio frequency pulse is emitted according to a preset time-encoding matrix, and the size of the time-encoding matrix is N*(N-1); the construction method of the time-encoding matrix is as follows: an N-order square matrix formed by the arterial spin labeling links of the N cycles is encoded to obtain an initial encoding matrix with a size of N*N, wherein the labeling block is recorded as +1 and the control block is recorded as -1 in the initial encoding matrix, the initial encoding matrix Hn satisfies Hn*Hn’=NI, wherein Hn’ is the transpose of Hn and I is a unit matrix; a column of all +1 in the initial encoding matrix is deleted to obtain a time-encoding matrix with a size of (N-1)*N; the renal perfusion measurement result of the subject is obtained by registering the renal arterial spin labeling sequence image and the M0 image, which comprises the following steps: 1) using a non-rigid registration algorithm, the renal arterial spin labeling sequence image is registered layer by layer to obtain a preliminary registered renal arterial spin labeling sequence image, wherein the number of the renal arterial spin labeling sequence images is N×average number×number of layers, and the average number is the number of times of completing the renal arterial spin labeling sequence when the renal arterial spin labeling sequence image is acquired; 2) using a non-rigid or rigid registration algorithm, the preliminary registered renal arterial spin labeling sequence image obtained in step 1) is registered layer by layer with the M0 image to obtain a final registered renal arterial spin labeling sequence image; 3) based on the time-encoding matrix, the final registered renal arterial spin labeling sequence image is decoded and averaged to obtain renal perfusion weighted images under different delay times, and the number of the renal perfusion weighted images is (N-1)×number of layers. 4) using a kinetic model for arterial spin labeling, fitting the renal perfusion weighted images at different delay times obtained in step 3) to obtain quantitative maps of renal blood flow perfusion and arterial transit time, which are the renal perfusion measurement results of the subject.

2. The method of claim 1, wherein, Also comprising: The pre-saturation pulse link uses a single saturation pulse or a combined saturation pulse to zero the signal at the imaging level before the arterial spin labeling link to eliminate errors caused by incomplete relaxation; The post-labeling delay link is used to wait for the labeled blood to flow from the labeling level to the subject's kidney; The data acquisition link is used to acquire images of the subject's kidney.

3. The method of claim 2, wherein, Before the acquiring of the time-encoding based renal arterial spin labeling sequence images of the subject, the method further comprises: Positioning the renal arterial spin labeling sequence to determine the imaging frame position of the renal arterial spin labeling sequence in the subject's abdomen.

4. The method of claim 3, wherein, Before the acquiring of the M0 image of the subject's kidney, the method further comprises: Positioning the acquisition sequence of the M0 image, and the positioning result of the acquisition sequence of the M0 image is consistent with the positioning result of the renal arterial spin labeling sequence.

5. A one-stop multi-delay arterial spin labeling renal perfusion measurement apparatus, characterized by, Comprising: A renal arterial spin labeling sequence image acquisition module for acquiring time-encoding based renal arterial spin labeling sequence images of a subject; An M0 image acquisition module for acquiring an M0 image of the subject's kidney, the M0 image being consistent with the number of layers, resolution, and image acquisition mode of the renal arterial spin labeling sequence images; A post-processing module for obtaining renal perfusion measurement results of the subject by registering the renal arterial spin labeling sequence images and the M0 image; Wherein, the time-encoding based renal arterial spin labeling sequence images are acquired by setting a renal arterial spin labeling sequence on a magnetic resonance scanner; the renal arterial spin labeling sequence consists of N cycles, N≥4 and is an integer multiple of 4; wherein each cycle includes a pre-saturation pulse link, an arterial spin labeling link, a post-labeling delay link, and a data acquisition link; The arterial spin labeling link is used to emit radio frequency pulses according to a set encoding to label the blood flowing through the subject's kidney; the arterial spin labeling link is a combination of N-1 labeling blocks and control blocks, wherein the blood signal is labeled in the labeling blocks and remains unchanged in the control blocks; both the labeling blocks and the control blocks consist of continuous small-angle radio frequency pulses and gradients, so that the ideal cumulative phase of the labeling blocks is 2π and the ideal cumulative phase of the control blocks is 0; the radio frequency pulses are emitted according to a preset time encoding matrix, and the size of the time encoding matrix is N*(N-1); The construction method of the time encoding matrix is: An initial encoding matrix of N*N size is obtained by encoding an N-order square matrix formed by N cycles of arterial spin labeling loops, wherein a labeling block is recorded as +1 and a control block is recorded as -1 in the initial encoding matrix, the initial encoding matrix Hn satisfies Hn*Hn'=I, wherein Hn' is the transpose of Hn, and I is a unit matrix; a column of all +1 in the initial encoding matrix is deleted, and a time encoding matrix of (N-1)*N size is obtained; The kidney perfusion measurement result of the subject is obtained by registering the renal arterial spin labeling sequence images and the M0 image, including: 1) using a non-rigid group registration algorithm, the renal arterial spin labeling sequence images are registered layer by layer to obtain the preliminary registered renal arterial spin labeling sequence images, wherein the number of the renal arterial spin labeling sequence images=N×average number×number of layers, the average number is the number of times of completing the renal arterial spin labeling sequence when collecting the renal arterial spin labeling sequence images; 2) using a non-rigid or rigid registration algorithm, the preliminary registered renal arterial spin labeling sequence images obtained in step 1) are registered layer by layer with the M0 image to obtain the final registered renal arterial spin labeling sequence images; 3) based on the time encoding matrix, the final registered renal arterial spin labeling sequence images are decoded and averaged to obtain kidney perfusion weighted images under different delay times, and the number of the kidney perfusion weighted images is (N-1)×number of layers; 4) using a kinetic model for arterial spin labeling, the kidney perfusion weighted images under different delay times obtained in step 3) are fitted to obtain a kidney blood perfusion quantitative map and an arterial transit time quantitative map, which are the kidney perfusion measurement results of the subject.

6. An electronic device, comprising: It comprises: at least one processor; and a memory in communication connection with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are configured to execute the method of any one of claims 1-4.

7. A computer readable storage medium characterized in that, The computer readable storage medium stores computer instructions for causing the computer to execute the method of any one of claims 1-4.

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