CN110680325B - Perfusion imaging method and device - Google Patents

Abstract

This application is applicable to the field of medical imaging technology, and provides a perfusion imaging method and device, including: applying a saturation pulse on the marking layer according to the resonance frequency of the substance to be measured, and the saturation pulse is used to excite the blood to be measured flowing through the marking layer. Substances chemically exchange with free water molecules to complete the signal labeling of free water molecules; the first magnetic resonance signal of signal-labeled free water molecules is collected in the imaging layer; when the marking layer is not applied with a saturation pulse, the imaging layer is collected The second magnetic resonance signal of free water molecules that have not been signal-labeled after flowing through the labeling layer, wherein, along the direction of blood flow, the labeling layer is located upstream of the target area, the imaging layer is located in the target area, and after flowing through the labeling layer Free water molecules and the substance to be tested flow into the imaging layer with the blood; the second magnetic resonance signal is subtracted from the first magnetic resonance signal to obtain a difference signal; perfusion images.

Description

A perfusion imaging method and device

technical field

The present application relates to the technical field of medical imaging, in particular to a perfusion imaging method and device.

Background technique

Magnetic Resonance Imaging (MRI) technology is the core technology in medical imaging. Using magnetic resonance imaging technology to image the perfusion process of blood entering the tissue (also called perfusion imaging), the obtained perfusion images allow people to observe the perfusion of blood after entering the tissue, and provide a reference for assessing the health of the tissue.

Arterial spin labeling (ASL) tracking is a common perfusion imaging method. By marking the free water molecules in the blood upstream of the tissue, that is, the MRI equipment marks the free water molecules in the blood upstream of the tissue, so that the relaxation parameters of the free water molecules change. A perfusion image of the tissue is then acquired based on changes in the relaxation parameters of free water molecules.

However, the existing ASL tracking method often obtains the perfusion imaging of free water molecules, which can only reflect the perfusion of blood after entering the tissue, but cannot know the perfusion of specific substances in the blood in the tissue.

Contents of the invention

In view of this, the present application provides a perfusion imaging method and device, aiming at acquiring a perfusion image when a specific substance in blood is perfused into a target area.

In the first aspect, the present application provides a perfusion imaging method, including: applying a saturation pulse on the labeling layer according to the resonance frequency of the substance to be tested, and the saturation pulse is used to excite the substance to be tested in the blood flowing through the labeling layer and free water molecules Chemical exchange to complete the signal labeling of free water molecules; the first magnetic resonance signal of the signal-labeled free water molecules is collected in the imaging layer; The second magnetic resonance signal of the free water molecules marked by the signal, wherein, along the direction of blood flow, the marking layer is located at the upstream position of the target area, the imaging layer is located at the target area, and the free water molecules flowing through the marking layer and the target area The substance flows into the imaging layer with the blood; the second magnetic resonance signal is subtracted from the first magnetic resonance signal to obtain a difference signal; according to the difference signal, the perfusion image of the substance to be tested is obtained when the substance is perfused into the target area with the blood.

Using the perfusion imaging method provided in this application, the MRI equipment applies saturation pulses to the labeling layer through the resonant frequency of the substance to be tested, and excites the substance to be tested to perform chemical exchange with free water molecules, thereby realizing the signal labeling of free water molecules corresponding to the substance to be tested . Furthermore, after the imaging layer collects the first magnetic resonance signal and the second magnetic resonance signal of free water molecules before and after being marked by the signal, the MRI equipment can obtain the measured The perfusion image of the substance in the target area realizes the acquisition of specific perfusion images for different substances to be tested.

Optionally, the method further includes: calculating chemical parameters of the substance to be tested according to the difference signal.

Based on this optional method, the MRI equipment uses chemical exchange saturation transfer (chemical exchange saturation transfer, CEST) method to excite the analyte and free water molecules in the marking layer to perform chemical exchange, so as to realize the signal labeling of the free water molecules corresponding to the analyte. Furthermore, after the imaging layer collects the first magnetic resonance signal and the second magnetic resonance signal of free water molecules before and after being marked by the signal, the MRI equipment can calculate the measured The chemical parameters of the substance realize the process of quantifying the chemical parameters of the substance to be measured.

In a second aspect, the present application provides a perfusion imaging device, including: a labeling unit, configured to apply a saturation pulse on the labeling layer according to the resonance frequency of the substance to be tested, and the saturation pulse is used to excite the substance to be tested in the blood flowing through the labeling layer Carry out chemical exchange with free water molecules to complete the signal labeling of free water molecules; the acquisition unit is used to collect the first magnetic resonance signal of signal-labeled free water molecules on the imaging layer; and when the marking layer is not applied with a saturation pulse , the imaging layer collects the second magnetic resonance signal of free water molecules that have not been signal-labeled after flowing through the labeling layer, wherein, along the direction of blood flow, the labeling layer is located upstream of the target area, the imaging layer is located in the target area, and the flow The free water molecules and the substance to be tested flow into the imaging layer with the blood after passing through the marking layer; the calculation unit is used to subtract the second magnetic resonance signal from the first magnetic resonance signal to obtain a difference signal; the imaging unit is used to obtain a difference signal according to The difference signal acquires a perfusion image when the substance to be tested is perfused into the target area along with the blood.

Optionally, the calculation unit is also used to calculate the chemical parameters of the substance to be tested according to the difference signal.

It can be understood that the perfusion imaging device may be an MRI device, or a chip in the MRI device, or a functional module integrated in the MRI device. Wherein, the chip or the functional module can be located in the control center (for example, console) of the MRI equipment, and control the MRI equipment to implement the perfusion imaging method provided in the present application.

It can be understood that, for the beneficial effects of the perfusion imaging device described in the second aspect, reference may be made to the description of the corresponding beneficial effects of the perfusion imaging method in the first aspect, which will not be repeated here.

Based on the above first or second aspect, optionally, the above chemical parameters include chemical exchange rate and/or concentration of the substance to be tested.

计算化学交换速率和/或浓度；其中，CESTR表示待测物质的化学交换饱和转移率，取值为差值信号的信号强度；f_s表示待测物质的浓度；k_CA表示待测物质的化学交换速率；R_1w表示自由水分子的纵向驰豫率；σ所述饱和脉冲的溢出因子。Optionally, calculate the chemical parameters of the substance to be tested according to the difference signal, including: using the formula

Calculate the chemical exchange rate and/or concentration; among them, CESTR represents the chemical exchange saturation transfer rate of the test substance, and the value is the signal intensity of the difference signal; f _s represents the concentration of the test substance; k _CA represents the chemical Exchange rate; R _1w represents the longitudinal relaxation rate of free water molecules; σ is the overflow factor of the saturation pulse.

Optionally, the imaging parameters used when acquiring the first magnetic resonance signal at the imaging layer are the same as the imaging parameters used when acquiring the second magnetic resonance signal.

Optionally, the above-mentioned substances to be tested may be metabolites or drugs in blood.

In a third aspect, the present application provides an MRI device, including a processor, a memory, and a computer program stored in the memory and operable on the processor, characterized in that, when the processor executes the computer program, the above-mentioned first aspect or The perfusion imaging method described in any optional mode of the first aspect.

In a fourth aspect, the present application provides a computer-readable storage medium, which stores a computer program, and is characterized in that, when the computer program is executed by a processor, any optional Methods described perfusion imaging method.

In a fifth aspect, the present application provides a computer program product. When the computer program product is run on a control device, the control device is made to execute the perfusion imaging method described in the first aspect or any optional manner of the first aspect.

It can be understood that, for the beneficial effects of the above third aspect to the fifth aspect, reference may be made to the relevant description in the above first aspect, which will not be repeated here.

Description of drawings

In order to illustrate the technical solution in this application more clearly, the accompanying drawings that need to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some implementations of the present invention For example, those skilled in the art can also obtain other drawings based on these drawings without paying creative labor.

Fig. 1 is a flowchart of an embodiment of a perfusion imaging method provided by the present application;

Fig. 2 is a schematic diagram of a marking layer and an imaging layer provided by the present application;

Fig. 3 is a schematic diagram of a perfusion image provided by the present application;

Fig. 4 is a flowchart of another embodiment of a perfusion imaging method provided by the present application;

Fig. 5 is a schematic structural diagram of a perfusion imaging device provided by the present application;

Fig. 6 is a schematic structural diagram of an MRI device provided by the present application.

Detailed ways

In the following description, for purposes of illustration rather than limitation, specific details, such as specific system architectures and techniques, are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the invention may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

Reference to "one embodiment" or "some embodiments" or the like in the specification of the present application means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in other embodiments," etc. in various places in this specification are not necessarily All refer to the same embodiment, but mean "one or more but not all embodiments" unless specifically stated otherwise. The terms "including", "comprising", "having" and variations thereof mean "including but not limited to", unless specifically stated otherwise.

In addition, in the description of the specification and appended claims of the present application, the terms "first", "second", "third" and so on are only used to distinguish descriptions, and should not be understood as indicating or implying relative importance.

In order to illustrate the technical solutions provided by the present application, specific examples are used below to illustrate.

Referring to FIG. 1, it is a flow chart of an embodiment of a perfusion imaging method provided by the present application, the method comprising:

In step 101, the MRI equipment applies a saturation pulse to the labeling layer according to the resonance frequency of the substance to be tested, and the saturation pulse is used to excite the substance to be tested in the blood flowing through the labeling layer to chemically exchange with free water molecules, so as to complete the signal labeling of free water molecules.

Wherein, the marking layer is located upstream of the arterial blood flow in the target area, that is, along the direction of blood flow, and the marking layer is located upstream of the target area. The target area is an area where perfusion images need to be obtained, for example, brain tissue, myocardial tissue, kidney tissue, and the like. Exemplarily, as shown in FIG. 2 , the position of the marking layer is upstream of the arterial blood flow of the brain tissue, and the arrow indicates the direction of blood flow.

In this application, the substance to be tested may be a substance in the blood that can undergo chemical exchange with free water molecules, including metabolites in the blood or drugs that enter the blood. Wherein, the chemical exchange between the test substance in the blood and the free water molecules refers to the energy exchange between the exchangeable protons (such as hydrogen protons) in the test substance and the hydrogen protons of the free water molecules.

The MRI equipment can be based on the chemical exchange saturation transfer (chemical exchange saturation transfer, CEST) method, and a saturation pulse is applied to the marking layer according to the resonant frequency of the substance to be measured. The exchangeable protons in the substance to be tested flowing through the labeling layer apply a saturation pulse to saturate the exchangeable protons. The saturated exchangeable protons chemically exchange with the hydrogen protons of free water molecules, and a part of the energy is transferred to the hydrogen protons of free water molecules, so that the magnetic resonance signal of the hydrogen protons of free water molecules is changed from the second magnetic resonance signal (that is, by The magnetic resonance signal before signal labeling) is reduced to the first magnetic resonance signal, and then the signal labeling of free water molecules is completed.

Step 102, the MRI equipment collects the first magnetic resonance signal of the signal-labeled free water molecule on the imaging layer.

Wherein, the imaging layer is located in the target area (for example, where the imaging layer is located as shown in FIG. 2 ), and is used to collect perfusion data when blood flows into the target area to perfuse the target area, so as to facilitate subsequent generation of perfusion images.

In this application, free water molecules are signal-labeled as they flow through the labeling layer to which a saturation pulse is applied. Then, when the signal-labeled free water molecules flow into the imaging layer of the target area along with the blood, the MRI equipment can collect the first magnetic resonance signals of the signal-labeled free water molecules.

Step 103 , when no saturation pulse is applied to the marking layer, the MRI equipment collects second magnetic resonance signals of free water molecules that have not been signal-marked after flowing through the marking layer on the imaging layer.

In this application, the MRI equipment needs to acquire the first magnetic resonance signal and the second magnetic resonance signal based on the same imaging parameters. That is, the imaging parameters used by the MRI equipment when acquiring the first magnetic resonance signal at the imaging layer are the same as the imaging parameters used when acquiring the second magnetic resonance signal, so as to ensure subsequent accurate difference signals. Wherein, the imaging parameters may include acquisition trajectory, reconstruction parameters and the like.

It is worth noting that the MRI equipment can first apply a saturation pulse to the labeling layer to collect the first magnetic resonance signal of the free water molecule marked by the signal, and then turn off the saturation pulse to collect the second magnetic resonance signal of the free water molecule not marked by the signal Signal. It is also possible to first collect the second magnetic resonance signal of the free water molecule not marked with the signal, and then apply a saturation pulse to the marking layer and collect the first magnetic resonance signal of the free water molecule marked with the signal. That is to say, the MRI device may first execute steps 101-102, and then execute step S103, or may first execute step S103, and then execute steps 101-102.

Step 104, the MRI equipment subtracts the second magnetic resonance signal from the first magnetic resonance signal to obtain a difference signal.

The MRI equipment subtracts the first magnetic resonance signal from the second magnetic resonance signal to obtain a difference signal.

Step 105, the MRI equipment acquires a perfusion image when the substance to be tested is perfused into the target area along with the blood according to the difference signal.

Exemplarily, the target area is brain tissue as an example. As shown in FIG. 3 , the MRI equipment does not apply a saturation pulse to the marker layer, and the image generated based on the second magnetic resonance signal collected in the imaging layer is image 1 . The MRI equipment applies a saturation pulse to the marking layer, and the image generated based on the first magnetic resonance signal collected in the imaging layer is image 2 . The MRI device generates a perfusion image of the substance to be tested in the brain tissue based on the difference signal between the second magnetic resonance signal and the first magnetic resonance signal. It can also be considered that by subtracting image 1 and image 2, the perfusion image when the substance to be tested is perfused into the brain tissue can be obtained. It can be seen that the perfusion image obtained by the MRI equipment can intuitively see the perfusion situation of the substance to be tested in the brain tissue.

In summary, with the perfusion method provided in this application, the MRI equipment uses the CEST method to excite the substance to be tested on the labeling layer to perform chemical exchange with free water molecules, thereby realizing the signal labeling of free water molecules. Furthermore, after the imaging layer collects the first magnetic resonance signal and the second magnetic resonance signal of free water molecules before and after being marked by the signal, the MRI equipment can obtain the measured The perfusion image of the substance in the target area realizes the acquisition of specific perfusion images for different substances to be tested.

In an embodiment, after the MRI equipment obtains the difference signal, it can further quantify the chemical parameters of the substance to be tested according to the difference signal. For example, see FIG. 4 , which is a flow chart of another embodiment of a perfusion imaging method provided by the present application. As shown in FIG. 4 , the difference between this embodiment and the embodiment corresponding to FIG. 1 is that after step 205 the The method further includes step 206. Steps 201 to 205 in this embodiment are the same as steps 101 to 105 in the embodiment corresponding to FIG. 1 . For details, please refer to the relevant description of the embodiment corresponding to FIG. 1 , and details are not repeated here. Step 206 is specifically as follows:

Step 206, the MRI equipment calculates the chemical parameters of the substance to be tested according to the difference signal.

Wherein, the chemical parameter of the substance to be tested may be the concentration and/or chemical exchange rate of the substance to be tested, or other chemical parameters.

Exemplarily, when the chemical parameter of the substance to be tested is the concentration and/or the chemical exchange rate of the substance to be tested, in a possible implementation, the MRI equipment may continue to apply the energy of the saturation pulse to the marking layer, and calculate The concentration and/or chemical exchange rate of the substance to be measured.

For example, the MRI device can calculate chemical exchange rates and/or concentrations using equation (1) below.

Among them, f _s represents the concentration of the analyte; k _CA represents the chemical exchange rate of the analyte; R _1w represents the longitudinal relaxation rate of free water molecules; α represents the saturation efficiency of the analyte. σ is the overflow factor of the saturation pulse. CESTR represents the chemical exchange saturation transfer ratio of the substance to be measured, and is taken as the signal intensity of the difference signal. The MRI equipment will bring the signal strength of each difference signal collected in the target area into formula (1) one by one for calculation, and finally obtain f _s and/or k _CA .

To sum up, using the perfusion imaging method provided in this application, the MRI equipment uses the CEST method to excite the substance to be tested and free water molecules in the labeling layer for chemical exchange, so as to realize the signal labeling of the free water molecules corresponding to the substance to be tested. Furthermore, after the imaging layer collects the first magnetic resonance signal and the second magnetic resonance signal of free water molecules before and after being marked by the signal, the MRI equipment can calculate the measured The chemical parameters of the substance realize the process of quantifying the chemical parameters of the substance to be measured.

It should be understood that the sequence numbers of the steps in the above embodiments do not mean the order of execution, and the execution order of each process should be determined by its functions and internal logic, and should not constitute any limitation to the implementation process of the present application.

Corresponding to the perfusion imaging method described in the above embodiments, Fig. 5 shows a structural block diagram of a perfusion imaging device provided by the present application, and for the convenience of description, only the parts relevant to the present application are shown.

Referring to FIG. 5 , the perfusion imaging device includes: a marking unit 51 , an acquisition unit 52 , a calculation unit 53 and an imaging unit 54 .

The marking unit 51 is used to apply a saturation pulse to the marking layer according to the resonant frequency of the substance to be measured, and the saturation pulse is used to excite the substance to be measured in the blood flowing through the marking layer to chemically exchange with free water molecules, so as to complete the signal marking of free water molecules .

The acquisition unit 52 is used to acquire the first magnetic resonance signal of the free water molecules marked by the signal on the imaging layer; The second magnetic resonance signal of water molecules, wherein, along the direction of blood flow, the marking layer is located upstream of the target area, the imaging layer is located in the target area, and the free water molecules and substances to be tested flow into the marking layer with the blood imaging layer.

The computing unit 53 is configured to subtract the second magnetic resonance signal from the first magnetic resonance signal to obtain a difference signal.

The imaging unit 54 is configured to acquire a perfusion image when the substance to be tested is perfused into the target area along with the blood according to the difference signal.

Optionally, the calculation unit 53 is also used to calculate chemical parameters of the substance to be tested according to the difference signal.

The specific way in which the marking unit 51 applies a saturation pulse on the marking layer, the specific way in which the acquisition unit 42 acquires the first magnetic resonance signal and the second magnetic resonance signal, the specific way in which the calculation unit 53 calculates the difference signal and chemical parameters, and the acquisition by the imaging unit 54 For the specific manner of the perfusion image of the substance to be tested in the target area, reference may be made to the relevant descriptions in the above embodiments shown in FIGS. 1-4 , which will not be repeated here.

In this application, the perfusion imaging device may be an MRI device, or a chip in the MRI device, or a functional module integrated in the MRI device. Wherein, the chip or the functional module can be located in the control center (for example, console) of the MRI equipment, and control the MRI equipment to implement the perfusion imaging method provided in the present application.

Referring to Fig. 6, a kind of MRI equipment provided for the present application comprises: at least one processor 60 (only one is shown in Fig. 6 ) processor, memory 61 and be stored in memory 61 and can be on at least one processor 60 The running computer program 62, when the processor 60 executes the computer program 62, implements the steps in the above embodiment of the perfusion imaging method. For example, when the processor 60 executes the computer program 62, the above steps 101-105 and steps 201-206 are realized.

The so-called processor 60 may be a central processing unit (Central Processing Unit, CPU), and the processor 60 may also be other general-purpose processors, a digital signal processor (Digital Signal Processor, DSP), an application specific integrated circuit (Application Specific Integrated Circuit) , ASIC), off-the-shelf programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor, or the processor may be any conventional processor, or the like.

The memory 61 may be an internal storage unit of the MRI device in some embodiments, such as a hard disk or memory of the MRI device. The memory 61 may also be an external storage device of the MRI device in other embodiments, such as a plug-in hard disk equipped on the MRI device, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, Flash card (Flash Card), etc. Further, the memory 61 may also include both an internal storage unit of the MRI device and an external storage device. The memory 61 is used to store an operating system, application programs, boot loader (BootLoader), data and other programs, such as program codes of the computer program 62 . The memory 61 can also be used to temporarily store data that has been output or will be output.

Those skilled in the art can understand that Fig. 6 is only an example of MRI equipment, and does not constitute a limitation to MRI equipment, and may include more or less components than shown in the figure, or combine some components, or different components, for example It can also include input and output devices, network access devices, scanners, etc.

Those skilled in the art can clearly understand that for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used for illustration. In practical applications, the above-mentioned functions can be assigned to different functional units, Completion of modules means that the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment may be integrated into one processing unit, or each unit may exist separately physically, or two or more units may be integrated into one unit, and the above-mentioned integrated units may adopt hardware It can also be implemented in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the protection scope of the present application. For the specific working process of the units and modules in the above system, reference may be made to the corresponding process in the foregoing method embodiments, and details will not be repeated here.

In the above-mentioned embodiments, the descriptions of each embodiment have their own emphases, and for parts that are not detailed or recorded in a certain embodiment, refer to the relevant descriptions of other embodiments.

Those skilled in the art can appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal equipment and method may be implemented in other ways. For example, the device/terminal device embodiments described above are only illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units Or components may be combined or may be integrated into another system, or some features may be omitted, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

If the integrated module/unit is realized in the form of a software function unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention realizes all or part of the processes in the methods of the above embodiments, and can also be completed by instructing related hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer When the program is executed by the processor, the steps in the above-mentioned various method embodiments can be realized.

Correspondingly, the present application provides a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the perfusion imaging method as provided in the present application is implemented.

The present application also provides a computer program product, which, when the computer program product runs on the MRI equipment, causes the MRI equipment to execute the perfusion imaging method provided in the present application.

Wherein, the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer memory, and a read-only memory (ROM, Read-Only Memory) , Random Access Memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, computer-readable media Excludes electrical carrier signals and telecommunication signals.

The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still implement the foregoing embodiments Modifications to the technical solutions described in the examples, or equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the application, and should be included in the Within the protection scope of this application.

Claims (10)

1. A perfusion imaging method, comprising: A saturation pulse is applied to the marking layer according to the resonant frequency of the substance to be measured, and the saturation pulse is used to excite the substance to be measured in the blood flowing through the marking layer to perform chemical exchange with free water molecules, so as to complete the separation of the free water molecules signal mark; acquiring a first magnetic resonance signal of signal-labeled free water molecules at the imaging layer; When the saturation pulse is not applied to the marking layer, a second magnetic resonance signal of free water molecules that are not signal-labeled after flowing through the marking layer is collected on the imaging layer, wherein, along the direction of blood flow , the marking layer is located upstream of the target area, the imaging layer is located in the target area, free water molecules and the analyte flowing through the marking layer flow into the imaging layer with blood, the The first magnetic resonance signal and the second magnetic resonance signal are acquired based on the same imaging parameters; subtracting the second magnetic resonance signal from the first magnetic resonance signal to obtain a difference signal; Acquiring a perfusion image when the substance to be tested is perfused into the target area along with the blood according to the difference signal. 2. The method according to claim 1, characterized in that the method further comprises: The chemical parameters of the substance to be tested are calculated according to the difference signal. 3. The method according to claim 2, wherein the chemical parameters include the chemical exchange rate and/or concentration of the substance to be tested. 4. The method according to claim 3, wherein the calculating the chemical parameters of the substance to be tested according to the difference signal comprises: use the formula

Calculate chemical exchange rates and/or concentrations; Wherein, CESTR represents the chemical exchange saturation transfer rate of the analyte, which is the signal intensity of the difference signal; f _s represents the concentration of the analyte; k _CA represents the chemical exchange of the analyte Rate; R _1w represents the longitudinal relaxation rate of free water molecules; σ overflow factor of the saturation pulse; α represents the saturation efficiency of the analyte. 5 . The method according to claim 1 , wherein the imaging parameters used when acquiring the first magnetic resonance signal at the imaging layer are the same as the imaging parameters used when acquiring the second magnetic resonance signal. 6. The method according to any one of claims 1-5, wherein the substance to be tested is a metabolite or a drug in blood. 7. A perfusion imaging device, comprising: The marking unit is used to apply a saturation pulse on the marking layer according to the resonant frequency of the substance to be tested, and the saturation pulse is used to excite the substance to be tested in the blood flowing through the marking layer to perform chemical exchange with free water molecules, so as to complete the A signal label for free water molecules; an acquisition unit, configured to acquire a first magnetic resonance signal of a signal-labeled free water molecule on the imaging layer; and when the saturation pulse is not applied to the marker layer, acquire the signal flowing through the marker layer The second magnetic resonance signal of free water molecules that are not labeled by the signal, wherein, along the direction of blood flow, the labeling layer is located upstream of the target area, the imaging layer is located in the target area, and flows through the The free water molecules behind the marking layer and the substance to be measured flow into the imaging layer with the blood, and the first magnetic resonance signal and the second magnetic resonance signal are collected based on the same imaging parameters; a calculation unit, configured to subtract the second magnetic resonance signal from the first magnetic resonance signal to obtain a difference signal; An imaging unit, configured to acquire a perfusion image of the substance to be tested when the substance is perfused into the target area along with the blood according to the difference signal. 8. The perfusion imaging device according to claim 7, characterized in that, The calculation unit is further configured to calculate chemical parameters of the substance to be tested according to the difference signal. 9. A magnetic resonance imaging MRI device, comprising a processor, a memory, and a computer program stored in the memory and operable on the processor, characterized in that, when the processor executes the computer program, it realizes The perfusion imaging method according to any one of claims 1 to 6. 10. A computer-readable storage medium, the computer-readable storage medium storing a computer program, characterized in that, when the computer program is executed by a processor, the perfusion imaging according to any one of claims 1 to 6 is realized method.

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