Vascular imaging system, method and device, and electronic device and storage medium

Abstract

A vascular imaging system, method and device, and an electronic device and a storage medium. The vascular imaging system comprises: an ultrasound device, which is used for collecting intravascular ultrasound images of a target object; an angiography device, which is used for collecting coronary angiography images of the target object; and a processing device, which is connected to both the ultrasound device and the angiography device, and is used for: determining a waveform-free interval of a diastolic phase within a cardiac cycle of the target object; respectively acquiring, from the images respectively collected by the ultrasound device and the angiography device, a target ultrasound image and a target angiography image of a target blood vessel of the target object within the waveform-free interval of the diastolic phase; performing vascular reconstruction on the basis of the target ultrasound image and the target angiography image, so as to generate a vascular model for the target blood vessel; and determining a fractional flow reserve of the target blood vessel on the basis of vascular parameters in the vascular model. The solution can reduce the discomfort of a subject, save on the test costs of the subject, and facilitate an improvement in the calculation precision of the fractional flow reserve of the target blood vessel.

Description

Vascular imaging system, method, device, electronic device and storage medium Technical Field

[0001] The present application relates to the technical field of image acquisition and processing, and more specifically to a vascular imaging system, a vascular imaging method, a vascular imaging device, an electronic device, and a computer-readable storage medium. Background Art

[0002] Fractional flow reserve (FFR) is defined as the ratio of the maximum blood flow that can be obtained in the myocardial area innervated by the coronary artery under the condition of stenosis to the maximum blood flow that can be obtained in the same area under normal conditions. FFR truly reflects the impact of coronary artery stenosis caused by obstruction on its function, and describes the limitation of the maximum myocardial blood flow in the case of coronary stenosis. In the case of maximum hyperemia (when the coronary resistance is the smallest and relatively constant), the blood flow in the coronary artery is linearly related to the pressure. Therefore, the value of FFR can be simplified as the average pressure distal to the coronary stenosis in the maximum hyperemia state (P d ) and the mean pressure at the aortic root or coronary artery ostium (P a ) ratio.

[0003] In the prior art, FFR is primarily measured by measuring the ratio of arterial pressure distal to the stenosis during maximal hyperemia using a pressure-sensitive guidewire or microcatheter. This process typically requires the administration of vasodilators (such as adenosine) to achieve maximal vascular hyperemia. The measurement process must span several cardiac cycles to ensure that intracoronary pressure is at its lowest and relatively stable. However, even after administration of potent drugs such as adenosine, intracoronary resistance is not static but rather fluctuates in a phased pattern throughout the cardiac cycle. These fluctuations reflect changes in myocardial and microvascular function during systole (high intracoronary resistance and microvascular compression) and diastole (low intracoronary resistance). Therefore, to minimize these effects, FFR typically calculates the maximum flow rate to the vascular bed during hyperemia and averages it over several cardiac cycles to ensure constant and minimal intracoronary resistance. Consequently, the entire process is time-consuming and requires high standards for drug dosage and administration. Furthermore, individual patient responses and tolerance to drugs vary, which can also affect measurement accuracy. Adenosine also has related contraindications in clinical use, such as asthma, severe chronic obstructive pulmonary disease, hypotension and bradycardia, which further limit its clinical use.

[0004] Summary of the Invention

[0005] The present application is proposed in view of the above problems. The present application provides a vascular imaging system, a vascular imaging method, a vascular imaging device, an electronic device and a computer-readable storage medium.

[0006] According to one aspect of the present application, a vascular imaging system is provided, comprising: an ultrasound device for acquiring an ultrasound image within a blood vessel of a target object; an angiography device for acquiring a coronary angiography image of the target object; a processing device, connected to the ultrasound device and the angiography device, respectively, and configured to: determine a diastolic waveform-free interval within the cardiac cycle of the target object; obtain a target ultrasound image and a target angiography image of a target blood vessel of the target object within the diastolic waveform-free interval from images acquired by the ultrasound device and the angiography device, respectively; perform vascular reconstruction based on the target ultrasound image and the target angiography image to generate a vascular model of the target blood vessel; and determine a blood flow reserve fraction of the target blood vessel based on vascular parameters in the vascular model.

[0007] Exemplarily, the vascular imaging system also includes an electrocardiogram device for acquiring an electrocardiogram signal of a target object, and a processing device is connected to the electrocardiogram device, wherein the processing device determines the diastolic waveform-free interval within the cardiac cycle of the target object in the following manner: receiving the electrocardiogram signal of the target object from the electrocardiogram device; identifying the diastolic waveform-free interval based on the electrocardiogram signal; the processing device is also used to: when the start moment of the diastolic waveform-free interval is identified, control the ultrasound device to start acquiring an intravascular ultrasound image; when the end moment of the diastolic waveform-free interval is identified, control the ultrasound device to stop acquiring the intravascular ultrasound image; the processing device obtains a target ultrasound image of the target blood vessel of the target object within the diastolic waveform-free interval from the image acquired by the ultrasound device in the following manner: acquiring the intravascular ultrasound image acquired by the ultrasound device as the target ultrasound image.

[0008] Exemplarily, the vascular imaging system also includes an electrocardiogram device for acquiring an electrocardiogram signal of a target object, and a processing device is connected to the electrocardiogram device, wherein the processing device determines the diastolic waveform-free interval within the cardiac cycle of the target object in the following manner: receiving the electrocardiogram signal of the target object from the electrocardiogram device; identifying the diastolic waveform-free interval based on the electrocardiogram signal; the processing device obtains a target ultrasound image of a target blood vessel of the target object within the diastolic waveform-free interval from an image acquired by an ultrasound device in the following manner: selecting a target ultrasound image from an intravascular ultrasound image acquired by the ultrasound device based on the identified diastolic waveform-free interval; wherein the ultrasound device and the electrocardiogram device synchronously acquire their respective corresponding intravascular ultrasound images and electrocardiogram signals, and the ultrasound device continuously acquires intravascular ultrasound images.

[0009] Exemplarily, the vascular imaging system also includes an electrocardiogram device for acquiring an electrocardiogram signal of a target object, and a processing device is connected to the electrocardiogram device. The processing device determines the diastolic waveform-free interval within the cardiac cycle of the target object in the following manner: receiving the electrocardiogram signal of the target object from the electrocardiogram device; identifying the diastolic waveform-free interval based on the electrocardiogram signal; the processing device is also used to: when the start moment of the diastolic waveform-free interval is identified, control the angiography device to start acquiring coronary angiography images; when the end moment of the diastolic waveform-free interval is identified, control the angiography device to stop acquiring coronary angiography images; the processing device obtains a target angiography image of the target blood vessel of the target object within the diastolic waveform-free interval from the image acquired by the angiography device in the following manner: selecting at least two frames of angiography images at different angiography angles as target angiography images from the coronary angiography images acquired by the angiography device.

[0010] Exemplarily, the vascular imaging system also includes an electrocardiogram device for acquiring an electrocardiogram signal of a target object, and a processing device is connected to the electrocardiogram device, and the processing device determines the diastolic waveform-free interval within the cardiac cycle of the target object in the following manner: receiving the electrocardiogram signal of the target object from the electrocardiogram device; identifying the diastolic waveform-free interval based on the electrocardiogram signal; the processing device obtains a target angiography image of a target blood vessel of the target object within the diastolic waveform-free interval from an image acquired by an angiography device in the following manner: based on the identified diastolic waveform-free interval, selecting at least two frames of candidate coronary angiography images of different angiography angles from the coronary angiography images acquired by the angiography device as target angiography images; wherein the candidate coronary angiography images are coronary angiography images acquired by the angiography device during the diastolic waveform-free interval; wherein the angiography device and the electrocardiogram device synchronously acquire their respective corresponding coronary angiography images and electrocardiogram signals, and the angiography device continuously acquires coronary angiography images.

[0011] Exemplarily, the processing device identifies the diastolic waveform-free interval based on the ECG signal in the following manner: calculating the instantaneous resistance at each moment in the cardiac cycle based on the waveform amplitude characteristics of the ECG signal; and determining the diastolic waveform-free interval based on the instantaneous resistance at each moment in the cardiac cycle.

[0012] Exemplarily, the processing device performs blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel in the following manner: identifying the centerline of the target blood vessel from the target angiography image; identifying the lumen contour of the target blood vessel from the target ultrasound image; and aligning and reconstructing the lumen contour along the centerline to obtain a blood vessel model.

[0013] Exemplarily, the processing device is also used to: identify side branches of the target blood vessel from the target ultrasound image; the processing device aligns and reconstructs the lumen contour along the centerline to obtain a blood vessel model by aligning and reconstructing the side branches along the centerline together with the lumen contour.

[0014] Exemplarily, the ultrasound device includes an ultrasound catheter and an ultrasound transducer arranged on the ultrasound catheter; the ultrasound transducer is used to collect an intravascular ultrasound image of the target object during the retraction process of the ultrasound catheter; the processing device identifies the centerline of the target blood vessel from the target angiography image in the following manner: for each frame of coronary angiography image in the target angiography image, determine the retraction starting point and retraction end point of the ultrasound catheter in the coronary angiography image; based on the retraction starting point and retraction end point, extract the retraction path of the ultrasound catheter from the coronary angiography image; based on the retraction path corresponding to each frame of coronary angiography image in the target angiography image, generate a three-dimensional retraction path of the ultrasound catheter; wherein the centerline of the target blood vessel is represented by a three-dimensional retraction path.

[0015] Exemplarily, the processing device extracts the retraction path of the ultrasound catheter from the coronary angiography image based on the retraction starting point and the retraction end point in the following manner: preprocessing the coronary angiography image to obtain a preprocessed coronary angiography image, wherein the preprocessing includes filtering and / or histogram enhancement processing; performing vascular boundary enhancement on the target blood vessel in the preprocessed coronary angiography image to obtain a boundary-enhanced coronary angiography image; performing image binarization and morphological denoising processing on the boundary-enhanced coronary angiography image to obtain a processed coronary angiography image; extracting the shortest path with the retraction starting point as the starting point and the retraction end point as the end point from the processed coronary angiography image as the retraction path.

[0016] Exemplarily, the vascular parameters include the cross-sectional area corresponding to each point on the long axis of the vascular model, and the processing device determines the blood flow reserve fraction of the target blood vessel based on the vascular parameters in the vascular model in the following manner: determining the stenotic vascular segment and the normal vascular segment in the vascular model based on the size of the cross-sectional area corresponding to each point on the long axis of the vascular model; obtaining the mean arterial pressure of the target blood vessel; determining the pressure difference corresponding to the stenotic vascular segment based on the cross-sectional area corresponding to the stenotic vascular segment, the cross-sectional area corresponding to the normal vascular segment, and the length of the stenotic vascular segment; and determining the blood flow reserve fraction of the target blood vessel based on the mean arterial pressure and the pressure difference.

[0017] According to another aspect of the present application, a vascular imaging method is also provided, including: determining a diastolic waveform-free interval within a cardiac cycle of a target object; obtaining a target ultrasound image and a target angiography image of a target blood vessel of the target object within the diastolic waveform-free interval from images respectively acquired by an ultrasound device and an angiography device; performing vascular reconstruction based on the target ultrasound image and the target angiography image to generate a vascular model of the target blood vessel; and determining a blood flow reserve fraction of the target blood vessel based on vascular parameters in the vascular model.

[0018] Exemplarily, determining the diastolic waveform-free interval within the cardiac cycle of the target object includes: receiving an electrocardiogram signal of the target object from an electrocardiogram device; identifying the diastolic waveform-free interval based on the electrocardiogram signal; the method also includes: when the starting moment of the diastolic waveform-free interval is identified, controlling the ultrasound device to start acquiring the intravascular ultrasound image; when the ending moment of the diastolic waveform-free interval is identified, controlling the ultrasound device to stop acquiring the intravascular ultrasound image; obtaining a target ultrasound image of the target blood vessel of the target object within the diastolic waveform-free interval from the image acquired by the ultrasound device, including: obtaining the intravascular ultrasound image acquired by the ultrasound device as the target ultrasound image.

[0019] Exemplarily, determining the diastolic waveform-free interval within the cardiac cycle of the target object includes: receiving the electrocardiogram signal of the target object from an electrocardiogram device; identifying the diastolic waveform-free interval based on the electrocardiogram signal; obtaining a target ultrasound image of the target blood vessel of the target object within the diastolic waveform-free interval from an image acquired by an ultrasound device, including: selecting a target ultrasound image from the intravascular ultrasound images acquired by the ultrasound device based on the identified diastolic waveform-free interval; wherein the ultrasound device and the electrocardiogram device synchronously acquire their respective corresponding intravascular ultrasound images and electrocardiogram signals, and the ultrasound device continuously acquires the intravascular ultrasound images.

[0020] Exemplarily, determining the diastolic waveform-free interval within the cardiac cycle of the target object includes: receiving the electrocardiogram signal of the target object from an electrocardiogram device; identifying the diastolic waveform-free interval based on the electrocardiogram signal; the method also includes: when the starting moment of the diastolic waveform-free interval is identified, controlling the angiography device to start acquiring coronary angiography images; when the ending moment of the diastolic waveform-free interval is identified, controlling the angiography device to stop acquiring coronary angiography images; obtaining a target angiography image of the target blood vessel of the target object within the diastolic waveform-free interval from the image acquired by the angiography device, including: selecting at least two frames of coronary angiography images at different angiography angles from the coronary angiography images acquired by the angiography device as target angiography images.

[0021] Exemplarily, determining the diastolic waveform-free interval within the cardiac cycle of the target object includes: receiving the electrocardiogram (ECG) signal of the target object from an electrocardiogram (ECG) device; identifying the diastolic waveform-free interval based on the ECG signal; obtaining a target angiography image of the target blood vessel of the target object within the diastolic waveform-free interval from an image acquired by an angiography device, including: based on the identified diastolic waveform-free interval, selecting at least two frames of candidate coronary angiography images of different angiography angles as target angiography images from the coronary angiography images acquired by the angiography device; wherein the candidate coronary angiography image is a coronary angiography image acquired by the angiography device during the diastolic waveform-free interval; wherein the angiography device and the ECG device synchronously acquire their respective corresponding coronary angiography images and ECG signals, and the angiography device continuously acquires coronary angiography images.

[0022] Exemplarily, identifying the diastolic waveform-free interval based on the electrocardiogram signal includes: calculating the instantaneous resistance at each moment in the cardiac cycle based on the waveform amplitude characteristics of the electrocardiogram signal; and determining the diastolic waveform-free interval based on the instantaneous resistance at each moment in the cardiac cycle.

[0023] Exemplarily, blood vessel reconstruction is performed based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel, including: identifying the centerline of the target blood vessel from the target angiography image; identifying the lumen contour of the target blood vessel from the target ultrasound image; and aligning and reconstructing the lumen contour along the centerline to obtain a blood vessel model.

[0024] Exemplarily, before the lumen contour is registered and reconstructed along the centerline to obtain a vascular model, vascular reconstruction is performed based on the target ultrasound image and the target angiography image to generate a vascular model of the target blood vessel, which also includes: identifying side branches of the target blood vessel from the target ultrasound image; and registering and reconstructing the lumen contour along the centerline to obtain a vascular model, including: registering and reconstructing the side branches together with the lumen contour along the centerline.

[0025] Exemplarily, the ultrasound device includes an ultrasound catheter and an ultrasound transducer disposed on the ultrasound catheter; the ultrasound transducer is used to collect an intravascular ultrasound image of a target object during the retraction of the ultrasound catheter; identifying the centerline of the target blood vessel from the target angiography image, including: for each frame of coronary angiography image in the target angiography image, determining the retraction starting point and retraction end point of the ultrasound catheter in the coronary angiography image; based on the retraction starting point and retraction end point, extracting the retraction path of the ultrasound catheter from the coronary angiography image; generating a three-dimensional retraction path of the ultrasound catheter based on the retraction path corresponding to each frame of coronary angiography image in the target angiography image; wherein the centerline of the target blood vessel is represented by a three-dimensional retraction path.

[0026] Exemplarily, based on the retracement starting point and the retracement end point, the retracement path of the ultrasound catheter is extracted from the coronary angiography image, including: preprocessing the coronary angiography image to obtain a preprocessed coronary angiography image, wherein the preprocessing includes filtering and / or histogram enhancement processing; performing vascular boundary enhancement on the target blood vessel in the preprocessed coronary angiography image to obtain a boundary-enhanced coronary angiography image; performing image binarization and morphological denoising processing on the boundary-enhanced coronary angiography image to obtain a processed coronary angiography image; and extracting the shortest path with the retracement starting point as the starting point and the retracement end point as the end point from the processed coronary angiography image as the retracement path.

[0027] Exemplarily, the vascular parameters include the cross-sectional area corresponding to each point on the long axis of the vascular model; based on the vascular parameters in the vascular model, the blood flow reserve fraction of the target blood vessel is determined, including: determining the stenotic blood vessel segment and the normal blood vessel segment in the vascular model based on the size of the cross-sectional area corresponding to each point on the long axis of the vascular model; obtaining the mean arterial pressure of the target blood vessel; determining the pressure difference corresponding to the stenotic blood vessel segment based on the cross-sectional area corresponding to the stenotic blood vessel segment, the cross-sectional area corresponding to the normal blood vessel segment, and the length of the stenotic blood vessel segment; and determining the blood flow reserve fraction of the target blood vessel based on the mean arterial pressure and the pressure difference.

[0028] According to another aspect of the present application, a vascular imaging device is provided, comprising: a first determination module for determining a diastolic waveform-free interval within a cardiac cycle of a target object; an acquisition module for acquiring a target ultrasound image and a target angiography image of a target blood vessel of the target object within the diastolic waveform-free interval from images acquired by an ultrasound device and an angiography device, respectively; a blood vessel reconstruction module for performing blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel; and a second determination module for determining a blood flow reserve fraction of the target blood vessel based on blood vessel parameters in the blood vessel model.

[0029] According to another aspect of the present application, an electronic device is provided, comprising a processor and a memory, wherein the memory stores computer program instructions, and the computer program instructions are used by the processor to perform the following operations when executed: determining a diastolic waveform-free interval within the cardiac cycle of a target object; acquiring a target ultrasound image and a target angiography image of a target blood vessel of the target object within the diastolic waveform-free interval; performing blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel; and determining a blood flow reserve fraction of the target blood vessel based on blood vessel parameters in the blood vessel model.

[0030] According to another aspect of the present application, a computer-readable storage medium is provided, on which program instructions are stored, and the program instructions are used to perform the following operations when run: determine the diastolic waveform-free interval within the cardiac cycle of the target object; obtain a target ultrasound image and a target angiography image of the target blood vessel of the target object within the diastolic waveform-free interval; perform blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel; and determine the blood flow reserve fraction of the target blood vessel based on the blood vessel parameters in the blood vessel model.

[0031] According to the above technical solution, the blood flow reserve fraction of the target vessel is determined by obtaining a target ultrasound image and a target angiography image of the target vessel during the diastolic wave-free interval. The coronary artery resistance during the diastolic wave-free interval under normal conditions is not significantly different from the coronary artery resistance during the maximum hyperemia state achieved by applying vasodilator drugs such as adenosine. Therefore, this solution can achieve the measurement of the blood flow reserve fraction without the use of drugs. In addition, the present application can perform vascular reconstruction based on the target ultrasound image and the target angiography image to generate a vascular model of the target vessel, and determine the blood flow reserve fraction of the target vessel based on the vascular parameters in the vascular model. Therefore, this solution can determine the blood flow reserve fraction of the target vessel through algorithms such as vascular reconstruction without the need for pressure measurement. In summary, this solution is a minimally invasive method for determining the blood flow reserve fraction, which can reduce discomfort to the subject (i.e., the target object), reduce consumables during the test, reduce the subject's expenses and time, and thus save the subject's test costs. In addition, the duration of the waveform-free interval in diastole is longer, which is conducive to obtaining more ultrasound image data, so that a vascular model of the target blood vessel can be generated more accurately based on the ultrasound image data, which in turn is conducive to improving the calculation accuracy of the blood flow reserve fraction of the target blood vessel.

[0032] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and other purposes, features, and advantages of the present application will become more apparent through a more detailed description of the embodiments of the present application in conjunction with the accompanying drawings. The accompanying drawings are intended to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the drawings, the same reference numerals generally represent the same components or steps.

[0034] FIG1 is a schematic block diagram of a vascular imaging system according to an embodiment of the present application;

[0035] FIG2 is a schematic diagram showing a reconstructed blood vessel model according to one embodiment of the present application;

[0036] FIG3 is a schematic diagram showing a centerline of a target blood vessel according to one embodiment of the present application;

[0037] FIG4 shows a schematic flow chart of a blood vessel imaging method according to an embodiment of the present application;

[0038] FIG5 is a schematic block diagram of a blood vessel imaging device according to an embodiment of the present application;

[0039] FIG6 shows a schematic block diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of this application more apparent, the following exemplary embodiments of this application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of this application, rather than all the embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein. Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this application.

[0041] The commonly used method for measuring FFR is to use a pressure-guided catheter or microcatheter to measure the ratio of the pressure distal to the stenosis and the arterial pressure proximal to the lesion under conditions of maximum hyperemia to calculate the FFR. However, pressure-guided catheters are invasive and single-use, which increases the patient's costs and prolongs the interventional procedure. Furthermore, pressure-guided catheters can result in significant measurement errors in vessels with severe blockage and smaller lumens. Furthermore, during the measurement process, maximum hyperemia is typically achieved by injecting vasodilators, such as adenosine, into the patient's vein or artery. As mentioned above, vasodilators are somewhat harmful to the human body and are unsuitable for some patient groups (e.g., those with hepatic and renal insufficiency or drug allergies), significantly increasing measurement time and complexity. In light of this, the present application provides a vascular imaging system, method, device, electronic device, and computer-readable storage medium that, without the use of vasodilators, can accurately determine the target vessel's fractional flow reserve in a relatively short period of time. The vascular imaging system, method, device, electronic device, and computer-readable storage medium are described below.

[0042] To address the above technical issues, the present application provides a vascular imaging system. FIG1 shows a schematic block diagram of a vascular imaging system 100 according to one embodiment of the present application. As shown in FIG1 , the vascular imaging system 100 may include an ultrasound device 110 , an angiography device 120 , and a processing device 130 .

[0043] Ultrasound device 110 is used to acquire intravascular ultrasound images (also referred to as ultrasound images) of a target subject. Ultrasound device 110 is an intravascular ultrasound (IVUS) device. Ultrasound device 110 may include an ultrasound catheter, the top end of which may be equipped with an ultrasound transducer. The ultrasound catheter in ultrasound device 110 may be placed within a blood vessel, and the ultrasound transducer may be used to acquire the intravascular ultrasound image.

[0044] The angiography device 120 is used to acquire a coronary angiography image (which may be referred to as an angiography image) of the target object. The angiography device 120 is a coronary angiography (CAG) device. During coronary angiography, a contrast agent may be injected into the coronary artery to visualize the blood vessel under X-rays. The angiography device 120 may emit X-rays to acquire the corresponding coronary angiography image. Optionally, the blood vessel may be replaced with a blood vessel other than the coronary artery, and the implementation method is similar to that of the coronary artery, which will not be described in detail here.

[0045] The processing device 130 is connected to the ultrasound device 110 and the angiography device 120, respectively. The processing device 130 can be configured to perform the following operations: determine a diastolic waveform-free interval within a target subject's cardiac cycle; obtain a target ultrasound image and a target angiography image of a target vessel of the target subject during the diastolic waveform-free interval from images captured by the ultrasound device and the angiography device, respectively; perform vascular reconstruction based on the target ultrasound image and the target angiography image to generate a vascular model of the target vessel; and determine the fractional flow reserve of the target vessel based on vascular parameters in the vascular model.

[0046] It can be understood that the diastolic waveform-free interval refers to the period in the diastolic phase of the cardiac cycle when the resting coronary artery resistance reaches its minimum and is relatively constant. The coronary artery resistance during the diastolic waveform-free interval, under the premise that the blood vessels remain in a normal state (i.e., without the use of vasodilators), is not significantly different from the coronary artery resistance when the blood vessels reach a state of maximum congestion through the use of vasodilators such as adenosine. During the diastolic waveform-free interval, the blood flow and pressure in the blood vessels are linearly related, and the rise and fall of the pressure value can directly reflect the changes in blood flow, and thus reflect the true physiological stenosis of the blood vessels. Therefore, during the diastolic waveform-free interval, the coronary artery resistance of the target vessel can be directly measured without the need to inject vasodilators into the target vessel.

[0047] Optionally, the method for determining the diastolic waveform-free interval during the cardiac cycle can employ any existing or future method. In one embodiment, the diastolic waveform-free interval can be determined based on empirical values. For example, the start time of the diastolic waveform-free interval can be determined to be 112 ms after the onset of diastole, and the duration of the diastolic waveform-free interval can be determined to be 354 ms. In another embodiment, the diastolic waveform-free interval can be determined based on the electrocardiogram (ECG) signal of the target subject. The specific determination method is described below. The time period occupied by the diastolic waveform-free interval during the entire cardiac cycle can be the same or different for different target subjects. Optionally, the current target subject can be pre-tested to determine the time period occupied by its diastolic waveform-free interval during the entire cardiac cycle. Subsequently, vascular imaging can be performed on the current target subject. Based on the results of the previous test, it can be determined which of the acquired intravascular ultrasound images and coronary angiography images were acquired during the diastolic waveform-free interval. Optionally, during the process of vascular imaging of the current target object, it is also possible to determine in real time which period of time the diastolic waveform-free interval is in each cardiac cycle, and then determine in real time which intravascular ultrasound images and coronary angiography images are acquired during the diastolic waveform-free interval.

[0048] The processing device 130 may respectively obtain a target ultrasound image and a target angiography image of a target blood vessel of the target object in a diastolic waveform-free interval from the images acquired by the ultrasound device 110 and the angiography device 120 .

[0049] Optionally, the target blood vessel may be any blood vessel in the target subject's body for which FFR calculation is required, and the present application does not impose any restrictions on the location, blood vessel type, etc.

[0050] Optionally, the target ultrasound image and the target contrast imaging image can both be acquired directly by corresponding acquisition devices (e.g., ultrasound device 110 and contrast imaging device 120), or they can be acquired by performing image preprocessing on the acquired ultrasound image and contrast imaging image. Image preprocessing can include operations such as mean filtering. In some embodiments, the target ultrasound image and the target contrast imaging image can be acquired simultaneously. Alternatively, the target ultrasound image and the target contrast imaging image can be acquired asynchronously. This application is not limited to this.

[0051] Optionally, while ultrasound equipment 110 is capturing ultrasound images, it can withdraw an ultrasound catheter inserted into a blood vessel and utilize an ultrasound transducer mounted on the tip of the ultrasound catheter to capture and display an ultrasound image of the target vessel, i.e., a cross-sectional image of the target vessel, in real time. The ultrasound image captured by ultrasound equipment 110 can clearly display information such as the thickness of the vessel wall structure, the size and shape of the lumen, and so on. Therefore, by acquiring a target ultrasound image of the target vessel, the cross-sectional characteristics of the target vessel can be accurately determined.

[0052] The number of target ultrasound images can be selected based on actual needs. For any target vessel, the greater the number of ultrasound images corresponding to that target vessel, the more accurately the resulting vascular model will reflect the target vessel during subsequent vessel reconstruction. In some embodiments, target ultrasound images of the target vessel can be obtained by uniformly retracting an ultrasound catheter placed within the vessel. In this embodiment, the number of target ultrasound images obtained can be adjusted by adjusting the retraction speed of the ultrasound catheter and / or the acquisition frequency of the ultrasound transducer. Optionally, the target ultrasound images can be acquired using a high-speed retraction and high-frame-rate acquisition method. That is, the ultrasound device 110 can be used to acquire ultrasound images using a high retraction speed and a high imaging frame rate. This helps ensure that ultrasound images of the target vessel are acquired as quickly as possible, shortening acquisition time and facilitating the acquisition of a larger number of target ultrasound images, thereby more accurately determining the true target vessel structure. The high retraction speed can be, for example, 3 millimeters per second (mm / s), 6 mm / s, or 9 mm / s, and the high imaging frame rate can be, for example, 60 frames per second (frames / s) or 90 frames / s.

[0053] Optionally, the angiography device 120 can be an X-ray angiography machine, a CT scanner, etc. This application is not limited to this. Optionally, the number of target angiography images is at least two frames. Each frame of the at least two frames of target angiography images has a different angiography angle. The difference in the angiography angle between any two frames of the at least two frames of target angiography images satisfies an angle difference condition. The angle difference condition is that the difference in the angiography angle between the two frames of target angiography images is within the range of [30°, 150°]. In a specific embodiment, the number of target angiography images is two frames, and the difference in the angiography angle between the two frames of target angiography images is 60°. In this embodiment, by making each frame of the target angiography images have a different angiography angle, it helps to provide a more accurate basis for the subsequent vascular reconstruction step.

[0054] After acquiring the target ultrasound image and the target contrast image, the processing device 130 may perform blood vessel reconstruction based on the target ultrasound image and the target contrast image to generate a blood vessel model of the target blood vessel.

[0055] As can be understood, the target angiography image can provide the ultrasound catheter's retraction trajectory, geometric information along the target vessel's long axis, and the spatial location of the vessel's cross-sections. The target ultrasound image can also provide the morphological structure of multiple cross-sections of the target vessel. This embodiment, by fusing these two, facilitates accurate reconstruction of the target vessel's three-dimensional structure. The specific reconstruction method is described in detail below.

[0056] Acquiring target ultrasound images during many commonly used periods of the cardiac cycle, such as the end-diastole phase of each cardiac cycle, results in a smaller number of target ultrasound images collected during the shorter end-diastole phase, leading to significant data loss. Consequently, the amount of data used to reconstruct the vascular model is limited, and the reconstructed vascular model fails to accurately reflect the condition of the target vessel. In an embodiment of the present application, target ultrasound images are acquired during the waveform-free interval of diastole. Compared to other cardiac periods, such as the end-diastole phase, the echo-free interval is longer, enabling target ultrasound images to be acquired over a longer period of each cardiac cycle. This increases the number of target ultrasound images captured per cardiac cycle, allowing for more cross-sectional information of the target vessel to be obtained, thereby more accurately reflecting the condition of the target vessel. Furthermore, by increasing the acquisition period of target ultrasound images within each cardiac cycle, the ultrasound catheter retraction speed can be increased while ensuring sufficient target ultrasound image data, further improving image acquisition efficiency.

[0057] After obtaining the blood vessel model, the processing device 130 may determine the blood flow reserve fraction of the target blood vessel based on the blood vessel parameters in the blood vessel model.

[0058] Optionally, the vascular parameters may include characteristic data for each vascular cross-section in the vascular model, such as cross-sectional diameter, cross-sectional area, etc. The vascular parameters may also include the length of a specific vascular segment in the vascular model. For example, the specific vascular segment may be a stenotic vascular segment as described below.

[0059] During the diastolic waveform-free interval, a new pressure indicator that can be used to evaluate the degree of vascular stenosis without the need for vasodilator medication can be obtained through pressure measurement: the instantaneous wave-free ratio (iFR). iFR is defined as the mean pressure distal to the stenosis during the diastolic waveform-free interval divided by the mean arterial pressure during the diastolic waveform-free interval. The diastolic waveform-free interval can be determined using algorithms related to the calculation of iFR, or the coronary flow reserve (cFR) derived from iFR, or the diastolic hyperemia-free ratio (dFR) derived from iFR. The processing device 130 can perform vascular reconstruction based on the target ultrasound image and target angiography image acquired during the diastolic waveform-free interval to generate a vascular model. After obtaining the vascular parameters in the vascular model, the flow reserve fraction of the target vessel can be determined based on the mean arterial pressure in the target vessel and the blood flow velocity in the target vessel. The specific determination method is described in detail below.

[0060] According to the above technical solution, the blood flow reserve fraction of the target vessel is determined by obtaining a target ultrasound image and a target angiography image of the target vessel during the diastolic wave-free interval. The coronary artery resistance during the diastolic wave-free interval under normal conditions is not significantly different from the coronary artery resistance during the maximum hyperemia state achieved by applying vasodilator drugs such as adenosine. Therefore, this solution can achieve the measurement of the blood flow reserve fraction without the use of drugs. In addition, the present application can perform vascular reconstruction based on the target ultrasound image and the target angiography image to generate a vascular model of the target vessel, and determine the blood flow reserve fraction of the target vessel based on the vascular parameters in the vascular model. Therefore, this solution can determine the blood flow reserve fraction of the target vessel through algorithms such as vascular reconstruction without the need for pressure measurement. In summary, this solution is a minimally invasive method for determining the blood flow reserve fraction, which can reduce discomfort to the subject (i.e., the target object), reduce consumables during the test, reduce the subject's expenses and time, and thus save the subject's test costs. In addition, the duration of the waveform-free interval in diastole is longer, which is conducive to obtaining more ultrasound image data, so that a vascular model of the target blood vessel can be generated more accurately based on the ultrasound image data, which in turn is conducive to improving the calculation accuracy of the blood flow reserve fraction of the target blood vessel.

[0061] Exemplarily, the vascular imaging system further includes an electrocardiogram (ECG) device for acquiring an ECG signal of a target subject, and a processing device 130 is connected to the ECG device. The processing device 130 determines the diastolic waveform-free interval within the cardiac cycle of the target subject by: receiving the ECG signal of the target subject from the ECG device; and identifying the diastolic waveform-free interval based on the ECG signal. The processing device 130 obtains a target ultrasound image of a target blood vessel of the target subject within the diastolic waveform-free interval from an image acquired by the ultrasound device 110 by: selecting a target ultrasound image from the intravascular ultrasound images acquired by the ultrasound device 110 based on the identified diastolic waveform-free interval. The ultrasound device 110 and the ECG device synchronously acquire their respective corresponding intravascular ultrasound images and ECG signals, and the ultrasound device continuously acquires intravascular ultrasound images.

[0062] It is understood that the ultrasound image of the target blood vessel can be acquired in one or more cardiac cycles. The target ultrasound image includes an ultrasound image acquired in the diastolic waveform-free interval of each cardiac cycle.

[0063] It is understood that for different target subjects, the duration of the diastolic waveform-free interval in the target subject's cardiac cycle may vary. For the same target subject, the duration of the diastolic waveform-free interval in different cardiac cycles may also vary. Therefore, the diastolic waveform-free interval in each cardiac cycle can be determined separately. Therefore, compared to using empirical values ​​to determine the diastolic waveform-free interval in the cardiac cycle, determining the diastolic waveform-free interval based on the electrocardiogram signal is more helpful in ensuring the accuracy of the determined blood flow reserve fraction. The specific method for identifying the diastolic waveform-free interval based on the electrocardiogram signal is described in detail below.

[0064] In this embodiment, the ECG signal and ultrasound image are acquired synchronously. For any cardiac cycle, the ultrasound device can acquire multiple frames of ultrasound images during that cardiac cycle. It is possible that only some of the ultrasound images in the multiple frames correspond to the diastolic waveform-free interval. In some embodiments, the multiple frames of ultrasound images correspond to different acquisition times. In this embodiment, the diastolic waveform-free interval of the current cardiac cycle can be identified based on the ECG signal. Based on the time period corresponding to the diastolic waveform-free interval, the ultrasound image corresponding to that time period is selected from the multiple frames of ultrasound images. The selected ultrasound image is the target ultrasound image. For example, if the time period corresponding to the diastolic waveform-free interval of the current cardiac cycle is identified as being from 230 ms to 600 ms after the start of acquisition, the ultrasound image acquired between 230 ms and 600 ms after the start of acquisition can be selected from the multiple frames of ultrasound images acquired by the ultrasound device. The ultrasound image acquired within this time period is the target ultrasound image.

[0065] In the above embodiment, synchronously acquiring ECG signals and ultrasound images and selecting a target ultrasound image from the ultrasound images using the diastolic waveform-free interval determined based on the ECG signals helps ensure the accuracy of the vascular model generated based on the target ultrasound image, thereby further improving the accuracy of fractional flow reserve calculation. Furthermore, this embodiment continuously acquires ultrasound images, which helps increase imaging speed.

[0066] Exemplarily, the vascular imaging system further includes an electrocardiogram (ECG) device for acquiring an ECG signal of a target subject, and the processing device is connected to the ECG device. The processing device 130 determines the diastolic waveform-free interval within the cardiac cycle of the target subject by: receiving the ECG signal of the target subject from the ECG device; and identifying the diastolic waveform-free interval based on the ECG signal. The processing device 130 is further configured to: control the ultrasound device 110 to begin acquiring intravascular ultrasound images upon identifying the start of the diastolic waveform-free interval; and control the ultrasound device 110 to stop acquiring intravascular ultrasound images upon identifying the end of the diastolic waveform-free interval. The processing device 130 acquires a target ultrasound image of the target blood vessel of the target subject within the diastolic waveform-free interval from the image acquired by the ultrasound device 110 by: acquiring the intravascular ultrasound image acquired by the ultrasound device 110 as the target ultrasound image.

[0067] The electrocardiogram (ECG) signal can be acquired in real time by any existing or future electrocardiogram (ECG) device. It is understood that each cardiac cycle corresponds to a continuous ECG signal. The diastolic waveform-free interval in the corresponding cardiac cycle can be determined based on the ECG signal. Optionally, the start time of the diastolic waveform-free interval can correspond to a specific data point on the ECG signal. This data point can be referred to as the first data point. Similarly, the end time of the diastolic waveform-free interval can also correspond to a specific data point in the ECG. This data point can be referred to as the second data point. In one embodiment, when the first data point is identified, the ultrasound device 110 can be controlled to start acquiring ultrasound images. When the second data point is identified, the ultrasound device 110 can be controlled to stop acquiring ultrasound images. Thus, the ultrasound device 110 can be controlled to acquire sufficient target ultrasound images within the diastolic waveform-free interval. The specific method for identifying the diastolic waveform-free interval based on the ECG signal is described in detail below.

[0068] As described above, during the retraction of the ultrasound catheter within a blood vessel, the ultrasound transducer at the catheter's tip acquires an intravascular ultrasound image of the blood vessel. In this description, controlling the ultrasound device 110 to begin image acquisition may refer to controlling the ultrasound catheter placed within the blood vessel to begin retracting and acquire ultrasound images. Controlling the ultrasound device 110 to stop acquiring ultrasound images may refer to controlling the ultrasound catheter placed within the blood vessel to stop retracting and cease acquiring ultrasound images.

[0069] The above technical solution uses an ECG signal to trigger an ultrasound device to acquire ultrasound images of the target blood vessel. Consequently, this solution only acquires ultrasound images during the diastolic, waveform-free interval of the cardiac cycle, and does not acquire ultrasound images during periods other than the diastolic, waveform-free interval (e.g., the systolic, period). Compared to continuous ultrasound image acquisition, this solution prevents the loss of intravascular ultrasound images corresponding to periods other than the diastolic, allowing for more complete spatial geometric information of the target blood vessel, thereby improving computational accuracy. Furthermore, this solution minimizes the acquisition of useless ultrasound images (i.e., ultrasound images acquired during periods other than the diastolic, waveform-free interval), thereby improving ultrasound image utilization and reducing data redundancy. Preferably, the above triggered ultrasound image acquisition solution can be primarily applied to vascular imaging systems capable of high-speed retrieval and high-frame-rate acquisition. In such vascular imaging systems, the above triggered ultrasound image acquisition solution is relatively feasible.

[0070] Exemplarily, the vascular imaging system further includes an electrocardiogram (ECG) device for acquiring an ECG signal from a target subject, and a processing device is connected to the ECG device. The processing device 130 determines the diastolic waveform-free interval within the target subject's cardiac cycle by: receiving the target subject's ECG signal from the ECG device; and identifying the diastolic waveform-free interval based on the ECG signal. The processing device 130 obtains a target angiographic image of a target vessel of the target subject within the diastolic waveform-free interval from an image acquired by the angiography device 120 by: based on the identified diastolic waveform-free interval, selecting at least two candidate coronary angiography images from different angiography angles from among the coronary angiography images acquired by the angiography device 120 as target angiography images; wherein the candidate coronary angiography images are coronary angiography images acquired by the angiography device during the diastolic waveform-free interval. The angiography device and the ECG device synchronously acquire their respective coronary angiography images and ECG signals, with the angiography device continuously acquiring coronary angiography images.

[0071] As described above, during a cardiac cycle, the pressure and volume of the blood vessels change periodically. Therefore, to ensure the accuracy of the ultrasonic catheter's retraction trajectory and the geometric information of the target vessel's long axis determined based on the target angiographic image when generating the vascular model, an angiographic image during the diastolic waveform-free interval can be acquired as the target angiographic image. In this embodiment, the ECG signal and angiographic image are acquired synchronously. In a specific embodiment, after acquisition is completed, the diastolic waveform-free interval within each cardiac cycle can be first determined based on the ECG signal corresponding to each cardiac cycle. Then, from all angiographic images acquired by the angiographic device, an angiographic image corresponding to the diastolic waveform-free interval is selected as a candidate coronary angiographic image. Finally, at least two angiographic images with different angiographic angles can be selected from the candidate angiographic images as the target angiographic images. In this embodiment, the difference in the angiographic angle between any two of the at least two target angiographic images satisfies an angle difference condition. The angle difference condition has been described in detail above and will not be further elaborated here for the sake of brevity.

[0072] The above embodiment synchronously acquires the ECG signal and the angiography image, and selects the target angiography image from the angiography image using the diastolic waveform-free interval determined based on the ECG signal. This helps to ensure the accuracy of the vascular model generated based on the target angiography image, thereby further improving the calculation accuracy of the blood flow reserve fraction.

[0073] Exemplarily, the vascular imaging system further includes an electrocardiogram (ECG) device for acquiring an ECG signal from a target subject, and a processing device 130 is connected to the ECG device. The processing device 130 determines the diastolic waveform-free interval within the target subject's cardiac cycle by: receiving the target subject's ECG signal from the ECG device; and identifying the diastolic waveform-free interval based on the ECG signal. The processing device 130 is further configured to: upon identifying the start of the diastolic waveform-free interval, control the angiography device 120 to begin acquiring coronary angiography images; and upon identifying the end of the diastolic waveform-free interval, control the angiography device 120 to stop acquiring coronary angiography images. The processing device 130 obtains a target angiography image of a target vessel of the target subject within the diastolic waveform-free interval from the images acquired by the angiography device 120 by: selecting at least two frames of coronary angiography images acquired by the angiography device 120 at different angiography angles as target angiography images.

[0074] In this embodiment, all angiography images are acquired during the waveform-free interval of diastole. Alternatively, all angiography images acquired by the angiography device can be used as target angiography images. Alternatively, two angiography images acquired by the angiography device at different angiography angles can be selected as target angiography images. The difference in the angiography angles between the two target angiography images satisfies the angle difference requirement. In this embodiment, selecting only two angiography images as target angiography images helps reduce the amount of data required for vascular model generation, thereby further improving FFR calculation efficiency.

[0075] The above technical solution uses ECG signals to trigger the angiography device to acquire angiographic images of the target blood vessels. This minimizes the acquisition of useless angiographic images (i.e., images acquired during periods other than the diastolic, waveform-free interval), thereby improving angiographic image utilization and reducing data redundancy.

[0076] It should be noted that the aforementioned selection of images based on the diastolic waveform-free interval and the acquisition of images of the target blood vessels by the device triggered by the ECG signal can be combined to obtain the target ultrasound image and the target angiography image. This can include at least the following combinations:

[0077] 1) When the start moment of the diastolic waveform-free interval is identified, the ultrasound device is controlled to start acquiring intravascular ultrasound images and the angiography device is controlled to start acquiring coronary angiography images; when the end moment of the diastolic waveform-free interval is identified, the ultrasound device is controlled to stop acquiring intravascular ultrasound images and the angiography device is controlled to stop acquiring coronary angiography images; the intravascular ultrasound image acquired by the ultrasound device is obtained as a target ultrasound image; and from the coronary angiography images acquired by the angiography device, at least two frames of coronary angiography images at different angiography angles are selected as target angiography images.

[0078] 2) When the start moment of the diastolic waveform-free interval is identified, the ultrasound device is controlled to start acquiring the intravascular ultrasound image; when the end moment of the diastolic waveform-free interval is identified, the ultrasound device is controlled to stop acquiring the intravascular ultrasound image, and the intravascular ultrasound image acquired by the ultrasound device is obtained as the target ultrasound image; based on the identified diastolic waveform-free interval, at least two frames of candidate coronary angiography images with different angiography angles are selected from the coronary angiography images acquired by the angiography device as the target angiography image.

[0079] 3) Based on the identified diastolic waveform-free interval, a target ultrasound image is selected from the intravascular ultrasound images acquired by the ultrasound device; when the start moment of the diastolic waveform-free interval is identified, the angiography device is controlled to start acquiring coronary angiography images, and when the end moment of the diastolic waveform-free interval is identified, the angiography device is controlled to stop acquiring coronary angiography images, and at least two frames of coronary angiography images at different angiography angles are selected from the coronary angiography images acquired by the angiography device as target angiography images.

[0080] 4) Based on the identified diastolic waveform-free interval, a target ultrasound image is selected from the intravascular ultrasound image acquired by the ultrasound device; based on the identified diastolic waveform-free interval, at least two frames of candidate coronary angiography images at different angiography angles are selected as target angiography images from the coronary angiography images acquired by the angiography device.

[0081] Exemplarily, the processing device 130 identifies the diastolic waveform-free interval based on the ECG signal by calculating the instantaneous resistance at each moment in the cardiac cycle based on the waveform amplitude characteristics of the ECG signal. The diastolic waveform-free interval is determined based on the instantaneous resistance at each moment in the cardiac cycle.

[0082] It can be understood that by calculating the instantaneous resistance at each moment in the cardiac cycle, the hemodynamic changes of the target blood vessel in each cardiac cycle can be evaluated, and then the resistance index can be obtained. According to the resistance index at each moment, the period in the cardiac cycle when the resistance in the target blood vessel is the smallest and relatively stable can be identified. In some embodiments (such as the above-mentioned embodiment of synchronously acquiring the ECG signal and the ultrasound image or the angiography image), after synchronously acquiring the ECG signal and the ultrasound image or the angiography image, the instantaneous resistance at each moment in the cardiac cycle can be calculated based on the waveform amplitude characteristics of the ECG signal. And based on the instantaneous resistance at each moment, the period in the cardiac cycle when the resistance in the target blood vessel is the smallest and relatively stable (i.e., the waveform-free interval in the diastole) is determined.

[0083] In other embodiments (such as the aforementioned embodiment in which an ultrasound device is triggered based on an ECG signal to acquire an ultrasound image or angiography image of a target blood vessel), the ECG signal of the target subject can be pre-acquired before acquiring the image (ultrasound image or angiography image), and characteristic information of the diastolic waveform-free interval can be determined based on the ECG signal. This characteristic information can be the resistance index corresponding to the diastolic waveform-free interval of the target subject (hereinafter referred to as the resistance index threshold), or the start and end times of the diastolic waveform-free interval in each cardiac cycle. In a specific embodiment, the ECG signals of the target subject can be pre-acquired for multiple cardiac cycles. For each cardiac cycle, the instantaneous resistance at each moment in the cardiac cycle is calculated based on the waveform amplitude characteristics of the ECG signal corresponding to that cardiac cycle. Based on the instantaneous resistance at each moment, the period in the cardiac cycle when the resistance in the target blood vessel is minimum and relatively stable (i.e., the diastolic waveform-free interval) is determined. Then, based on the magnitude of the minimum resistance corresponding to each of the multiple cardiac cycles, the resistance index corresponding to the largest minimum resistance in the multiple cardiac cycles is determined as the resistance index threshold. When the ultrasound device is triggered based on the electrocardiogram signal to collect ultrasound images or angiography images of the target blood vessel, the instantaneous resistance at each moment in the cardiac cycle can be calculated based on the waveform amplitude characteristics of the electrocardiogram signal. When the resistance index corresponding to the instantaneous resistance at the current moment is less than or equal to the resistance index threshold, the current moment can be considered to be the beginning moment of the diastolic waveform-free interval in the cardiac cycle. Continue to calculate the instantaneous resistance at each moment in the cardiac cycle based on the waveform amplitude characteristics of the electrocardiogram signal. When the resistance index corresponding to the instantaneous resistance at the current moment is greater than the resistance index threshold, the current moment can be considered to be the end moment of the diastolic waveform-free interval in the cardiac cycle.

[0084] The above technical solution calculates the instantaneous resistance at each moment in the cardiac cycle based on the electrocardiogram signal and determines the diastolic waveform-free interval in the cardiac cycle based on the instantaneous resistance at each moment. This solution helps to more accurately determine the diastolic waveform-free interval in the cardiac cycle.

[0085] Exemplarily, the processing device performs blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel in the following manner: identifying the centerline of the target blood vessel from the target angiography image; identifying the lumen contour of the target blood vessel from the target ultrasound image; and aligning and reconstructing the lumen contour along the centerline to obtain a blood vessel model.

[0086] As described above, the target angiography image can provide the orientation of the blood vessel, i.e., the ultrasound catheter's retraction trajectory. Optionally, the ultrasound catheter's retraction trajectory can be determined based on the target angiography image and used as the target vessel's centerline. A specific method for identifying the target vessel's centerline from the target angiography image is described in detail below.

[0087] Optionally, the lumen contour of the target blood vessel can be identified from the target ultrasound image using any existing or future developed neural network model for image segmentation. For example, the neural network model can include one or more of the following neural network models: U-Net, Fully Convolutional Networks (FCN), Deep Convolutional Encoder-Decoder Structure for Image Segmentation (SegNet), etc. In a specific embodiment, a U-Net model can be selected and annotated ultrasound images can be used as training data so that the U-Net model can automatically segment the lumen contour of the blood vessel in the ultrasound image. In some embodiments, after the lumen contour of the target blood vessel is obtained using the neural network model, the result can be output and user feedback information (e.g., confirmation information or modification information) on the result can be received. Based on the feedback information, the lumen contour of the target blood vessel in the current ultrasound image is confirmed or modified, thereby completing the processing of the target ultrasound image.

[0088] Figure 2 shows a schematic diagram of a reconstructed blood vessel model according to one embodiment of the present application. As shown in Figure 2, the reconstruction process includes reconstruction of the target blood vessel's three-dimensional path, acquisition and processing of the target ultrasound image, and registration and reconstruction of the target angiographic image and the target ultrasound image.

[0089] Reconstructing the three-dimensional path of the target vessel may include: synchronously acquiring two frames of target angiography images during the diastolic waveform-free interval of the cardiac cycle using electrocardiographic signals; determining a retracement path (i.e., the centerline of the target vessel) based on each of the two frames of target angiography images; and completing the three-dimensional reconstruction of the retracement path using the retracement paths corresponding to the two frames of target angiography images.

[0090] The acquisition and processing of target ultrasound images involves triggering ultrasound image acquisition based on the waveform-free interval of the diastole of the electrocardiogram signal during the cardiac cycle. The acquired ultrasound image is the target ultrasound image. After acquisition is complete, the lumen contour in each target ultrasound image is identified.

[0091] The registration and reconstruction of the target angiographic image and the target ultrasound image involves registering the lumen contours in each target ultrasound image with the 3D retrieval path, determining the position of the lumen contours in each target ultrasound image frame. Surface fitting is then used to fit each lumen contour, completing the 3D reconstruction of the target vessel model.

[0092] Exemplarily, the processing device is further used to: identify side branches of a target blood vessel from a target ultrasound image; and when registering and reconstructing the lumen contour along the centerline to obtain a blood vessel model, register and reconstruct the side branches together with the lumen contour along the centerline.

[0093] In a specific implementation, side branch detection of a target vessel can be implemented using a deep learning algorithm based on a convolutional neural network, a Transformer model, or both. The above is merely an example; in actual implementation, other detection methods are possible, and this application does not limit this. It is understood that the presence of side branches in a target vessel may affect the reconstruction of the target vessel model and the calculation of the blood flow reserve fraction. This embodiment, by identifying the side branches of the target vessel, helps further improve the accuracy of the calculation of the blood flow reserve fraction.

[0094] After determining the centerline of the target vessel and the lumen contour of the target vessel in each target ultrasound image frame, registration and reconstruction can be performed. Registration and reconstruction can include the following operations. Using distance mapping, the lumen contour of each target ultrasound image frame is interpolated onto the centerline of the target vessel to determine the position of the lumen contour in each target ultrasound image frame. Surface fitting is then used to fit each lumen contour to complete the three-dimensional reconstruction of the target vessel model. In a specific embodiment, non-uniform rational B-spline (NURBS) curves can be used to fit each lumen contour, and the fitting results are smoothed to complete the three-dimensional reconstruction of the target vessel model. In an embodiment for identifying side branches, when registering and reconstructing the lumen contour along the centerline, the side branches can be registered and reconstructed along the centerline along with the lumen contour. Side branches are connected to the lumen contour, and the positional relationship between them is fixed. Therefore, identifying the side branches also provides information such as their position and shape on the lumen contour. Subsequently, the side branches can be registered and reconstructed along the lumen contour.

[0095] The above technical solution uses the centerline of the target vessel confirmed by the target angiographic image and the lumen contour in the target ultrasound image to complete the reconstruction of the vascular model. This embodiment facilitates accurate reconstruction of the vascular model of the target vessel, thereby facilitating the calculation accuracy of the blood flow reserve fraction.

[0096] Exemplarily, the ultrasound device 110 includes an ultrasound catheter and an ultrasound transducer mounted on the ultrasound catheter. The ultrasound transducer is configured to acquire ultrasound images of the target vessel during catheter retraction. The processing device 130 identifies the centerline of the target vessel from the target angiographic image by determining, for each coronary angiographic frame in the target angiographic image, the ultrasound catheter's retraction start and end points in the coronary angiographic image. Based on the retraction start and end points, the ultrasound catheter's retraction path is extracted from the coronary angiographic image. Based on the retraction path corresponding to each coronary angiographic frame in the target angiographic image, a three-dimensional retraction path of the ultrasound catheter is generated. The centerline of the target vessel is represented by the three-dimensional retraction path.

[0097] Optionally, the target angiography image includes at least two frames of coronary angiography images at different angiography angles, and the retrieval paths corresponding to the coronary angiography images at each angiography angle can be determined separately, and the three-dimensional retrieval path of the ultrasound catheter can be generated by fusing the retrieval paths at different angiography angles.

[0098] Optionally, the ultrasound catheter retraction start point and end point may be automatically determined in the target angiographic image by the processing device 130. Alternatively, the ultrasound catheter retraction start point and end point may be selected based on user needs. For example, the user may manually select the ultrasound catheter retraction start point and end point in the target angiographic image.

[0099] In the above embodiment, the ultrasound catheter's retraction path is used as the target vessel's centerline. Therefore, when identifying the target vessel's centerline based on the target angiography image, only the retraction path in the target angiography image needs to be extracted. This helps simplify the algorithm's complexity.

[0100] Exemplarily, the processing device 130 extracts the retraction path of the ultrasound catheter from the coronary angiography image based on the retraction start point and the retraction end point in the following manner: preprocessing the coronary angiography image to obtain a preprocessed coronary angiography image. The preprocessing includes filtering and / or histogram enhancement. The target blood vessels in the preprocessed coronary angiography image are enhanced to obtain a boundary-enhanced coronary angiography image. The boundary-enhanced coronary angiography image is binarized and subjected to morphological denoising to obtain a processed coronary angiography image. The shortest path starting from the retraction start point and ending at the retraction end point is extracted from the processed coronary angiography image as the retraction path.

[0101] Figure 3 illustrates a schematic diagram of identifying the centerline of a target vessel according to one embodiment of the present application. As shown in Figure 3, the method for identifying the centerline of a target vessel may include the following steps: a. Obtaining the starting point and end point of the target vessel for ultrasound imaging. The starting point (equivalent to the retracement starting point described above) and the end point (equivalent to the retracement end point described above) of the target vessel can be manually selected by the user in the target angiographic image. For example, the ultrasound catheter imaging point can be used as the starting point, and the angiographic guidance catheter used to acquire the target angiographic image can be used as the end point. In this embodiment, the starting point is point A in the figure, and the end point is point B in the figure. b. Performing image preprocessing on the target angiographic image. Preprocessing may include filtering and / or histogram enhancement. Filtering may be performed using any filtering method. For example, the target angiographic image may be subjected to average filtering and histogram enhancement. c. Performing vessel boundary enhancement on the target vessel in the target angiographic image. For example, a multi-scale Hessian matrix may be used to enhance the vessel boundary of the target vessel in the target angiographic image. d. Perform morphological processing on the target angiography image. In one embodiment, the target angiography image can first be binarized, and the grayscale value of the area corresponding to the blood vessels in the target angiography image is set to 255, and the grayscale value of the area other than the blood vessels is set to 0. Then, the target angiography image is subjected to morphological denoising processing to highlight the blood vessels in the target angiography image, thereby removing interference from other non-vascular areas. e. Extract the shortest path. In this step, based on the starting point and end point of the target blood vessel, and the target angiography image enhanced by steps b, c, and d, an existing shortest path algorithm such as the Dijkstra algorithm can be used to extract the shortest path. The shortest path is the retracement path of the ultrasound catheter in the target blood vessel (i.e., the centerline of the target blood vessel).

[0102] According to the above technical solution, by sequentially performing preprocessing, vessel boundary enhancement, image binarization, and morphological denoising on the angiography image, the image quality of the angiography image is improved, thereby facilitating accurate determination of the centerline of the target vessel.

[0103] Exemplarily, the vascular parameters include the cross-sectional area corresponding to each point on the long axis of the vascular model. Processing device 130 determines the FFR of the target vessel based on the vascular parameters in the vascular model in the following manner: determining stenotic and normal vessel segments in the vascular model based on the cross-sectional areas corresponding to each point on the long axis of the vascular model; obtaining the mean arterial pressure of the target vessel; determining the pressure differential corresponding to the stenotic vessel segment based on the cross-sectional area corresponding to the stenotic vessel segment, the cross-sectional area corresponding to the normal vessel segment, and the length of the stenotic vessel segment; and determining the FFR of the target vessel based on the mean arterial pressure and the pressure differential.

[0104] Optionally, based on the size of the cross-sectional area corresponding to each point on the long axis of the vascular model, a mutation point on the long axis corresponding to a sudden change in cross-sectional area can be identified along the long axis. It is understood that the diameter of a stenotic vascular segment is smaller than that of a normal vascular segment. In one embodiment, when identifying the cross-sectional area along the long axis, if the cross-sectional area corresponding to the current long axis point significantly changes in size relative to the cross-sectional area corresponding to the previous long axis point, for example, the cross-sectional area corresponding to the current long axis point is smaller than the cross-sectional area corresponding to the previous long axis point and the difference between the two is greater than a first preset difference threshold, then the current long axis point can be considered a mutation point. Cross-sectional area identification continues along the long axis. When another mutation point is identified, for example, if the cross-sectional area corresponding to the current long axis point is larger than the cross-sectional area corresponding to the previous long axis point and the difference between the two is greater than a second preset difference threshold, then the vascular segment between the two mutation points can be considered a stenotic vascular segment. The first preset difference threshold and the second preset difference threshold can be equal or different.

[0105] Optionally, the cross-sectional area corresponding to each point on the long axis of the vascular model can be compared with a preset area threshold. If the cross-sectional area of ​​a vascular segment in the vascular model is less than the preset area threshold, the vascular segment is considered a stenotic segment. Otherwise, the vascular segment is considered a normal segment. It will be appreciated that the preset area threshold can be determined based on the target subject and the target vessel type. Different target subjects and different types of target vessels may have different preset area thresholds.

[0106] Optionally, the mean arterial pressure of the target blood vessel can be measured based on any existing or future developed in vitro or in vivo pressure measurement method, which is not limited in this application.

[0107] It can be understood that FFR refers to the ratio of the maximum blood flow in the myocardium when the stenotic coronary artery is supplying blood to the maximum blood flow that the myocardium can obtain during normal blood flow supply from the same coronary artery. Since myocardial blood flow can be defined as: myocardial tissue blood flow = perfusion pressure / intramyocardial microcirculatory resistance, that is, Q = P / R, FFR can be calculated using the following formula:

[0108] Among them, P d Indicates the distal pressure of the stenotic vessel segment. a Indicates the proximal pressure of the stenotic vessel segment. The proximal pressure of the stenotic vessel segment is roughly equal to the pressure of the normal vessel segment, so the proximal pressure of the stenotic vessel segment can be used to represent the pressure of the normal vessel segment. v Indicates venous pressure. s Indicates the myocardial microcirculatory resistance of the stenotic vascular segment. NRepresents the myocardial microcirculatory resistance of a normal vascular segment. As mentioned above, there is no significant difference between the coronary artery resistance at the maximum hyperemia state achieved by vasodilators and the coronary artery resistance during the diastolic waveform-free interval under normal conditions (i.e., without the use of vasodilators). Therefore, the myocardial microcirculatory resistance during the diastolic waveform-free interval can be negligible and constant. Based on this, vascular reconstruction is performed, where the venous pressure P v is also close to 0, then the calculation formula of FFR can be simplified to:

[0109] Therefore, FFR can be calculated by dividing the distal pressure of the stenotic vessel segment during the diastolic waveform-free interval by the mean arterial pressure during the diastolic waveform-free interval.

[0110] It is understood that the distal pressure of the stenotic vessel segment can be obtained by calculating the pressure difference between the stenotic vessel segment and the normal vessel segment. d =P a -ΔP. The pressure difference can be calculated by a simplified fluid dynamics equation, namely ΔP = f v V+f s V 2 Where V represents the blood flow velocity in the target blood vessel. v Indicates the pressure loss coefficient caused by viscous friction. s Represents the local pressure loss coefficient caused by blood flow separation. v and f s They are all related to the length of the stenotic vessel segment, the cross-sectional area corresponding to the stenotic vessel segment, the cross-sectional area corresponding to the normal vessel segment, the blood flow viscosity coefficient, and the blood density. For example, the following relationship exists:

[0111] Among them, A s A represents the cross-sectional area of ​​the stenotic vessel segment. n represents the cross-sectional area of ​​a normal blood vessel segment. L represents the length of the stenotic blood vessel segment. μ represents the blood viscosity coefficient, and ρ represents the blood density.

[0112] Understandable, A. s 、A n Both μ and ρ can be determined based on empirical values.

[0113] Alternatively, the blood flow velocity in the target vessel can be calculated based on the transit time of the contrast agent from one location to another in the target angiographic image. It will be appreciated that during angiographic imaging of the target vessel, a contrast agent must be injected into the target vessel to visualize the blood flow in the target vessel. In one embodiment, any two frames of the target angiographic image containing the contrast agent can be selected, and the blood flow velocity in the target vessel can be calculated based on the distance traveled by the contrast agent in the two frames and the time interval between the acquisition of the two frames.

[0114] Alternatively, the blood flow velocity in the target vessel can be calculated using a frame counting method (e.g., the TIMI frame counting method). In this embodiment, the angiographic image includes all images from the first image captured when the contrast agent appears in the target vessel to the image captured when the contrast agent moves to the other end of the target vessel. After the contrast agent is injected into the target vessel, angiographic imaging of the target vessel can be performed at a preset imaging frequency to obtain multiple frames of angiographic images. The blood flow velocity in the target vessel can be calculated based on the number of angiographic images and the preset imaging frequency.

[0115] Therefore, after determining the pressure differential corresponding to the stenotic segment, the distal pressure of the stenotic segment can be further determined. The FFR is then calculated using the distal pressure of the stenotic segment and the mean arterial pressure. The specific calculation method has been described in detail above and will not be repeated here for the sake of brevity.

[0116] The above technical solution calculates the blood flow reserve fraction of the target vessel by using the distal pressure of the stenotic vessel segment and the mean arterial pressure, which is conducive to improving the calculation efficiency of the blood flow reserve fraction and ensuring good accuracy.

[0117] According to another aspect of the present application, a vascular imaging method is also provided. FIG4 shows a schematic flow chart of a vascular imaging method according to one embodiment of the present application. As shown in FIG4 , the method 400 may include the following steps S410 , S420 , S430 , and S440 .

[0118] In step S410 , a diastolic waveform-free interval in the cardiac cycle of the target subject is determined.

[0119] In step S420, a target ultrasound image and a target angiography image of a target blood vessel of the target object in a diastolic waveform-free interval are respectively acquired from images acquired by the ultrasound device and the angiography device.

[0120] In step S430 , blood vessel reconstruction is performed based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel.

[0121] In step S440 , the blood flow reserve fraction of the target blood vessel is determined based on the blood vessel parameters in the blood vessel model.

[0122] Exemplarily, determining the diastolic waveform-free interval within the cardiac cycle of the target subject may include the following steps: receiving an electrocardiogram (ECG) signal of the target subject from an electrocardiogram (ECG) device, and identifying the diastolic waveform-free interval based on the ECG signal.

[0123] The method 400 may further include the following steps: when the start of the diastolic waveform-free interval is identified, controlling the ultrasound device to start acquiring the intravascular ultrasound image, and when the end of the diastolic waveform-free interval is identified, controlling the ultrasound device to stop acquiring the intravascular ultrasound image.

[0124] Acquiring a target ultrasound image of a target blood vessel of a target object in a diastolic waveform-free interval from an image acquired by an ultrasound device may include the following steps: acquiring an intravascular ultrasound image acquired by the ultrasound device as the target ultrasound image.

[0125] Exemplarily, determining the diastolic waveform-free interval within the cardiac cycle of the target subject may include the following steps: receiving an electrocardiogram (ECG) signal of the target subject from an electrocardiogram (ECG) device, and identifying the diastolic waveform-free interval based on the ECG signal.

[0126] Acquiring a target ultrasound image of a target blood vessel of a target subject during a diastolic waveform-free interval from an image acquired by an ultrasound device may include the following steps: selecting the target ultrasound image from intravascular ultrasound images acquired by the ultrasound device based on the identified diastolic waveform-free interval. The ultrasound device and the electrocardiogram device synchronously acquire their respective corresponding intravascular ultrasound images and electrocardiogram signals, and the ultrasound device continuously acquires the intravascular ultrasound images.

[0127] Exemplarily, determining the diastolic waveform-free interval within the cardiac cycle of the target subject may include the following steps: receiving an electrocardiogram (ECG) signal of the target subject from an electrocardiogram (ECG) device, and identifying the diastolic waveform-free interval based on the ECG signal.

[0128] The method 400 may further include the following steps: when the start of the diastolic waveform-free interval is identified, controlling the angiography device to start acquiring coronary angiography images, and when the end of the diastolic waveform-free interval is identified, controlling the angiography device to stop acquiring coronary angiography images.

[0129] Obtaining a target angiography image of a target blood vessel of a target object during a diastolic waveform-free interval from an image acquired by an angiography device may include the following steps: selecting at least two frames of coronary angiography images at different angiography angles from the coronary angiography images acquired by the angiography device as target angiography images.

[0130] Exemplarily, determining the diastolic waveform-free interval within the cardiac cycle of the target subject may include the following steps: receiving an electrocardiogram (ECG) signal of the target subject from an electrocardiogram (ECG) device, and identifying the diastolic waveform-free interval based on the ECG signal.

[0131] Acquiring a target angiographic image of a target blood vessel of a target subject during a diastolic waveform-free interval from an image captured by an angiography device may include the following steps: based on the identified diastolic waveform-free interval, selecting at least two candidate coronary angiography images from different angiography angles from among the coronary angiography images captured by the angiography device as target angiography images. The candidate coronary angiography images are coronary angiography images captured by the angiography device during the diastolic waveform-free interval. The angiography device and the electrocardiography device synchronously capture their respective coronary angiography images and electrocardiogram signals, with the angiography device continuously capturing the coronary angiography images.

[0132] Illustratively, identifying the diastolic waveform-free interval based on the electrocardiogram signal may include the following steps: calculating the instantaneous resistance at each moment in the cardiac cycle based on the waveform amplitude characteristics of the electrocardiogram signal; and determining the diastolic waveform-free interval based on the instantaneous resistance at each moment in the cardiac cycle.

[0133] For example, performing vascular reconstruction based on a target ultrasound image and a target contrast-enhanced image to generate a vascular model of the target vessel may include the following steps: identifying a centerline of the target vessel from the target contrast-enhanced image; identifying a lumen contour of the target vessel from the target ultrasound image; and registering and reconstructing the lumen contour along the centerline to obtain a vascular model.

[0134] Exemplarily, method 400 may further include the following steps: identifying side branches of the target blood vessel from the target ultrasound image, and registering and reconstructing the lumen contour along the centerline to obtain the blood vessel model, and registering and reconstructing the side branches along the centerline together with the lumen contour.

[0135] Exemplarily, the ultrasound device includes an ultrasound catheter and an ultrasound transducer disposed on the ultrasound catheter. The ultrasound transducer is used to acquire an intravascular ultrasound image of a target object during the retraction of the ultrasound catheter. Identifying the centerline of a target blood vessel from a target angiography image may include the following steps: for each frame of a coronary angiography image in the target angiography image, determining a retraction start point and a retraction end point of the ultrasound catheter in the coronary angiography image. Based on the retraction start point and the retraction end point, extracting a retraction path of the ultrasound catheter from the coronary angiography image. Based on the retraction path corresponding to each frame of the coronary angiography image in the target angiography image, generating a three-dimensional retraction path of the ultrasound catheter. The centerline of the target blood vessel is represented by a three-dimensional retraction path.

[0136] Exemplarily, extracting the retraction path of the ultrasound catheter from the coronary angiography image based on the retraction start point and the retraction end point may include the following steps: preprocessing the coronary angiography image to obtain a preprocessed coronary angiography image. The preprocessing includes filtering and / or histogram enhancement processing. Performing vascular boundary enhancement on the target blood vessel in the preprocessed coronary angiography image to obtain a boundary-enhanced coronary angiography image. Performing image binarization and morphological denoising on the boundary-enhanced coronary angiography image to obtain a processed coronary angiography image. Extracting the shortest path from the processed coronary angiography image starting from the retraction start point and ending at the retraction end point as the retraction path.

[0137] Exemplarily, the vascular parameters include the cross-sectional area corresponding to each point on the long axis of the vascular model. Determining the Fractional Flow Reserve of the target vessel based on the vascular parameters in the vascular model may include the following steps: determining the stenotic and normal vessel segments in the vascular model based on the cross-sectional areas corresponding to each point on the long axis of the vascular model; obtaining the mean arterial pressure of the target vessel; determining the pressure differential corresponding to the stenotic segment based on the cross-sectional area corresponding to the stenotic segment, the cross-sectional area corresponding to the normal vessel segment, and the length of the stenotic segment; and determining the Fractional Flow Reserve of the target vessel based on the mean arterial pressure and the pressure differential.

[0138] According to another aspect of the present application, a vascular imaging device is also provided. Figure 5 shows a schematic block diagram of a vascular imaging device according to one embodiment of the present application. As shown in Figure 5 , vascular imaging device 500 includes a first determination module 510 , an acquisition module 520 , a vascular reconstruction module 530 , and a second determination module 540 .

[0139] The first determining module 510 is configured to determine a diastolic waveform-free interval within the cardiac cycle of the target subject.

[0140] The acquisition module 520 is configured to respectively acquire a target ultrasound image and a target angiography image of a target blood vessel of a target object in a diastolic waveform-free interval from images acquired by the ultrasound device and the angiography device respectively.

[0141] The blood vessel reconstruction module 530 is used to perform blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel.

[0142] The second determining module 540 is configured to determine the blood flow reserve fraction of the target blood vessel based on the blood vessel parameters in the blood vessel model.

[0143] Exemplarily, the first determination module 510 includes: a first receiving submodule for receiving an electrocardiogram (ECG) signal from a target subject from an electrocardiogram (ECG) device; a first identification submodule for identifying diastolic waveform-free intervals based on the ECG signal. The vascular imaging device also includes: a first control module for controlling the ultrasound device 500 to begin acquiring intravascular ultrasound images upon identifying the start of the diastolic waveform-free interval; and a second control module for controlling the ultrasound device to stop acquiring intravascular ultrasound images upon identifying the end of the diastolic waveform-free interval. The acquisition module 520 includes: a first acquisition submodule for acquiring the intravascular ultrasound image acquired by the ultrasound device as the target ultrasound image.

[0144] Exemplarily, the first determination module 510 includes a second receiving submodule for receiving an ECG signal from a target subject from an ECG device; and a second identification submodule for identifying diastolic waveform-free intervals based on the ECG signal. The acquisition module 520 includes a first selection submodule for selecting a target ultrasound image from intravascular ultrasound images acquired by an ultrasound device based on the identified diastolic waveform-free intervals. The ultrasound device and the ECG device synchronously acquire their respective corresponding intravascular ultrasound images and ECG signals. The ultrasound device continuously acquires the intravascular ultrasound images.

[0145] Exemplarily, the first determination module 510 includes: a third receiving submodule for receiving an electrocardiogram (ECG) signal from a target subject from an electrocardiogram (ECG) device; a third identification submodule for identifying diastolic waveform-free intervals based on the ECG signal. The vascular imaging device 500 also includes: a third control module for controlling the angiography device to begin acquiring coronary angiography images upon identifying the start of the diastolic waveform-free interval; and a fourth control module for controlling the angiography device to stop acquiring coronary angiography images upon identifying the end of the diastolic waveform-free interval. The acquisition module 520 includes: a second selection submodule for selecting at least two frames of coronary angiography images acquired by the angiography device from different angiography angles as target angiography images.

[0146] Exemplarily, the first determination module 510 includes: a fourth receiving submodule for receiving an electrocardiogram (ECG) signal of a target subject from an electrocardiogram (ECG) device; and a fourth identification submodule for identifying diastolic waveform-free intervals based on the ECG signal. The acquisition module 520 includes: a third selection submodule for selecting, based on the identified diastolic waveform-free intervals, at least two candidate coronary angiography images at different angiography angles from among the coronary angiography images acquired by the angiography device as target angiography images. The candidate coronary angiography images are coronary angiography images acquired by the angiography device during the diastolic waveform-free interval. The angiography device and the ECG device synchronously acquire their respective coronary angiography images and ECG signals, with the angiography device continuously acquiring coronary angiography images.

[0147] Exemplarily, the first determination module 510 includes: a calculation submodule for calculating the instantaneous resistance at each moment in the cardiac cycle based on the waveform amplitude characteristics of the electrocardiogram signal; and a first determination submodule for determining the diastolic waveform-free interval based on the instantaneous resistance at each moment in the cardiac cycle.

[0148] Exemplarily, the vascular reconstruction module 530 includes: a fifth identification submodule, used to identify the centerline of the target blood vessel from the target angiography image; a sixth identification submodule, used to identify the lumen contour of the target blood vessel from the target ultrasound image; and a reconstruction submodule, used to align and reconstruct the lumen contour along the centerline to obtain a vascular model.

[0149] Exemplarily, the vascular reconstruction module 530 also includes: a seventh identification submodule, which is used to identify the side branches of the target blood vessel from the target ultrasound image before the reconstruction submodule aligns and reconstructs the lumen contour along the center line to obtain the vascular model; the reconstruction submodule includes a reconstruction unit, which is used to align and reconstruct the side branches together with the lumen contour along the center line.

[0150] Exemplarily, the ultrasound device includes an ultrasound catheter and an ultrasound transducer disposed on the ultrasound catheter. The ultrasound transducer is used to acquire an ultrasound image of the target object's blood vessels during the ultrasound catheter's retraction process. The fifth identification submodule includes: a determination unit for determining, for each coronary angiography frame in the target angiography image, a retraction starting point and a retraction end point of the ultrasound catheter in the coronary angiography image; an extraction unit for extracting the retraction path of the ultrasound catheter from the coronary angiography image based on the retraction starting point and the retraction end point; and a generation unit for generating a three-dimensional retraction path of the ultrasound catheter based on the retraction path corresponding to each coronary angiography frame in the target angiography image. The centerline of the target blood vessel is represented by the three-dimensional retraction path.

[0151] Exemplarily, the extraction unit includes: a preprocessing subunit, used to preprocess the coronary angiography image to obtain a preprocessed coronary angiography image, wherein the preprocessing includes filtering and / or histogram enhancement processing; an enhancement subunit, used to perform vascular boundary enhancement on the target blood vessel in the preprocessed coronary angiography image to obtain a boundary-enhanced coronary angiography image; a binarization and denoising subunit, used to perform image binarization and morphological denoising processing on the boundary-enhanced coronary angiography image to obtain a processed coronary angiography image; an extraction subunit, used to extract the shortest path with the retracement starting point as the starting point and the retracement end point as the end point from the processed coronary angiography image as the retracement path.

[0152] Exemplarily, the vascular parameters include the cross-sectional area corresponding to each point on the long axis of the vascular model. The second determination module 540 includes: a second determination submodule for determining the stenotic and normal vascular segments in the vascular model based on the cross-sectional area corresponding to each point on the long axis; a second acquisition submodule for acquiring the mean arterial pressure of the target vessel; a third determination submodule for determining the pressure differential corresponding to the stenotic segment based on the cross-sectional area corresponding to the stenotic segment, the cross-sectional area corresponding to the normal segment, and the length of the stenotic segment; and a fourth determination submodule for determining the target vessel's fractional flow reserve based on the mean arterial pressure and the pressure differential.

[0153] According to another aspect of the present application, an electronic device is also provided. FIG6 shows a schematic block diagram of an electronic device according to an embodiment of the present application. As shown in the figure, the electronic device 600 includes a processor 610 and a memory 620, wherein the memory 620 stores computer program instructions, and the computer program instructions are used by the processor 610 to perform the following operations when executed: determining the diastolic waveform-free interval within the cardiac cycle of the target object; obtaining a target ultrasound image and a target angiography image of the target blood vessel of the target object within the diastolic waveform-free interval; performing vascular reconstruction based on the target ultrasound image and the target angiography image to generate a vascular model of the target blood vessel; and determining the blood flow reserve fraction of the target blood vessel based on the vascular parameters in the vascular model.

[0154] Exemplarily, a target ultrasound image is acquired by an ultrasound device; the computer program instructions, when executed by the processor 610, include the following steps: receiving an electrocardiogram (ECG) signal from the target subject from an electrocardiogram (ECG) device; and identifying the diastolic waveform-free interval based on the ECG signal. The computer program instructions, when executed by the processor 610, further include the following steps: controlling the ultrasound device to begin acquiring an intravascular ultrasound image upon identifying the start of the diastolic waveform-free interval; and controlling the ultrasound device to stop acquiring the intravascular ultrasound image upon identifying the end of the diastolic waveform-free interval. The computer program instructions, when executed by the processor 610, include the following steps: acquiring the intravascular ultrasound image acquired by the ultrasound device as the target ultrasound image.

[0155] The electrocardiogram device described herein may be included in a vascular imaging system or may be independent of the vascular imaging system. In one example, the vascular imaging system may further include an electrocardiogram device for acquiring an electrocardiogram signal of a target subject, and the processing device may be connected to the electrocardiogram device.

[0156] Exemplarily, the target ultrasound image is acquired by an ultrasound device; the computer program instructions executed by the processor 610 when executed include the steps of determining the diastolic waveform-free interval within the cardiac cycle of the target subject, including: receiving the target subject's electrocardiogram (ECG) signal from an electrocardiogram (ECG) device; and identifying the diastolic waveform-free interval based on the ECG signal. The computer program instructions executed by the processor 610 when executed include the steps of acquiring a target ultrasound image of a target blood vessel of the target subject within the diastolic waveform-free interval, including: selecting the target ultrasound image from intravascular ultrasound images acquired by the ultrasound device based on the identified diastolic waveform-free interval; wherein the ultrasound device and the ECG device synchronously acquire their respective corresponding intravascular ultrasound images and ECG signals, and the ultrasound device continuously acquires the intravascular ultrasound images.

[0157] Exemplarily, the target angiographic image is acquired by an angiography device; the computer program instructions, when executed by the processor 610, include the steps of determining the diastolic waveform-free interval within the target subject's cardiac cycle, including: receiving the target subject's electrocardiogram (ECG) signal from an electrocardiogram (ECG) device; and identifying the diastolic waveform-free interval based on the ECG signal. The computer program instructions, when executed by the processor 610, are further configured to: control the angiography device to begin acquiring coronary angiography images upon identifying the start of the diastolic waveform-free interval; and control the angiography device to stop acquiring coronary angiography images upon identifying the end of the diastolic waveform-free interval. The computer program instructions, when executed by the processor 610, include the steps of acquiring a target ultrasound image of a target vessel of the target subject within the diastolic waveform-free interval, including: selecting at least two frames of angiography images at different angiography angles from among the coronary angiography images acquired by the angiography device as target angiography images.

[0158] Exemplarily, the target angiographic image is acquired by an angiography device; the computer program instructions executed by the processor 610 when executed include the steps of determining the diastolic waveform-free interval within the cardiac cycle of the target subject, including: receiving the target subject's electrocardiogram (ECG) signal from an electrocardiogram (ECG) device; identifying the diastolic waveform-free interval based on the ECG signal; and the computer program instructions executed by the processor 610 when executed include the steps of acquiring the target angiographic image of the target vessel of the target subject within the diastolic waveform-free interval, including: based on the identified diastolic waveform-free interval, selecting at least two candidate coronary angiography images at different angiography angles from among the coronary angiography images acquired by the angiography device as the target angiography images. The candidate coronary angiography images are coronary angiography images acquired by the angiography device during the diastolic waveform-free interval. The angiography device and the ECG device synchronously acquire their respective coronary angiography images and ECG signals, and the angiography device continuously acquires the coronary angiography images.

[0159] Exemplarily, the steps of identifying the diastolic waveform-free interval based on the ECG signal executed by the computer program instructions when the processor 610 is running include: calculating the instantaneous resistance at each moment in the cardiac cycle based on the waveform amplitude characteristics of the ECG signal; and determining the diastolic waveform-free interval based on the instantaneous resistance at each moment in the cardiac cycle.

[0160] Exemplarily, the computer program instructions executed by the processor 610 when running perform blood vessel reconstruction based on the target ultrasound image and the target angiography image, and the steps of generating a blood vessel model of the target blood vessel include: identifying the centerline of the target blood vessel from the target angiography image; identifying the lumen contour of the target blood vessel from the target ultrasound image; and aligning and reconstructing the lumen contour along the centerline to obtain the blood vessel model.

[0161] For example, before the computer program instructions, when executed by processor 610, register and reconstruct the lumen contour along the centerline to obtain a blood vessel model, the computer program instructions, when executed by processor 610, further perform the following steps: identifying side branches of the target blood vessel from the target ultrasound image. The computer program instructions, when executed by processor 610, register and reconstruct the lumen contour along the centerline to obtain a blood vessel model include registering and reconstructing the side branches along the centerline with the lumen contour.

[0162] Exemplarily, a target ultrasound image is acquired by an ultrasound device; the ultrasound device includes an ultrasound catheter and an ultrasound transducer disposed on the ultrasound catheter; the ultrasound transducer is used to acquire an ultrasound image of the target object's blood vessel during the ultrasound catheter's retraction process; and the computer program instructions, when executed by the processor 610, include the following steps for identifying the centerline of the target blood vessel from the target angiography image. For each frame of coronary angiography in the target angiography image, a retraction starting point and a retraction end point of the ultrasound catheter in the coronary angiography image are determined. Based on the retraction starting point and the retraction end point, a retraction path of the ultrasound catheter is extracted from the coronary angiography image. Based on the retraction path corresponding to each frame of the coronary angiography in the target angiography image, a three-dimensional retraction path of the ultrasound catheter is generated. The centerline of the target blood vessel is represented by the three-dimensional retraction path.

[0163] Exemplarily, the computer program instructions executed by the processor 610 when running include the following operations: extracting the retraction path of the ultrasound catheter from the coronary angiography image based on the retraction start point and the retraction end point. Preprocessing the coronary angiography image to obtain a preprocessed coronary angiography image. Preprocessing includes filtering and / or histogram enhancement processing. Performing vascular boundary enhancement on the target blood vessel in the preprocessed coronary angiography image to obtain a boundary-enhanced coronary angiography image. Performing image binarization and morphological denoising on the boundary-enhanced coronary angiography image to obtain a processed coronary angiography image. Extracting the shortest path starting from the retraction start point and ending at the retraction end point from the processed coronary angiography image as the retraction path.

[0164] Exemplarily, the vascular parameters include the cross-sectional area corresponding to each point on the long axis of the vascular model. The steps for determining the blood flow reserve fraction of the target vessel based on the vascular parameters in the vascular model executed by the processor 610 when the computer program instructions are executed include: determining the stenotic vessel segment and the normal vessel segment in the vascular model based on the size of the cross-sectional area corresponding to each point on the long axis of the vascular model; obtaining the mean arterial pressure of the target vessel; determining the pressure difference corresponding to the stenotic vessel segment based on the cross-sectional area corresponding to the stenotic vessel segment, the cross-sectional area corresponding to the normal vessel segment, and the length of the stenotic vessel segment; and determining the blood flow reserve fraction of the target vessel based on the mean arterial pressure and the pressure difference.

[0165] According to another aspect of the present application, a computer-readable storage medium is provided, having program instructions stored thereon. When executed, the program instructions are configured to: determine a diastolic waveform-free interval within a target subject's cardiac cycle; obtain a target ultrasound image and a target angiography image of a target vessel of the target subject during the diastolic waveform-free interval; perform vascular reconstruction based on the target ultrasound image and the target angiography image to generate a vascular model of the target vessel; and determine the target flow reserve fractional flow of the target vessel based on vascular parameters in the vascular model. The computer-readable storage medium may, for example, include a storage component of a tablet computer, a hard drive of a personal computer, an erasable programmable read-only memory (EPROM), a compact disc read-only memory (CD-ROM), a USB memory device, or any combination thereof. The computer-readable storage medium may be any combination of one or more non-volatile storage media.

[0166] Exemplarily, the target ultrasound image is acquired by an ultrasound device; the step of determining the diastolic waveform-free interval within the cardiac cycle of the target subject, which is executed by the program instructions when executed, includes: receiving the target subject's electrocardiogram (ECG) signal from an electrocardiogram (ECG) device; and identifying the diastolic waveform-free interval based on the ECG signal. The program instructions, when executed, further include: controlling the ultrasound device to begin acquiring intravascular ultrasound images upon identifying the start of the diastolic waveform-free interval; and controlling the ultrasound device to stop acquiring intravascular ultrasound images upon identifying the end of the diastolic waveform-free interval. The step of acquiring a target ultrasound image of a target blood vessel of the target subject during the diastolic waveform-free interval, which is executed by the program instructions when executed, includes: acquiring the intravascular ultrasound image acquired by the ultrasound device as the target ultrasound image.

[0167] Exemplarily, the target ultrasound image is acquired by an ultrasound device; the program instructions, when executed, for determining the diastolic waveform-free interval within the cardiac cycle of the target subject include: receiving the target subject's electrocardiogram (ECG) signal from an electrocardiogram (ECG) device; and identifying the diastolic waveform-free interval based on the ECG signal. The program instructions, when executed, for acquiring the target ultrasound image of a target blood vessel of the target subject within the diastolic waveform-free interval include: selecting the target ultrasound image from intravascular ultrasound images acquired by the ultrasound device based on the identified diastolic waveform-free interval; wherein the ultrasound device and the ECG device synchronously acquire their respective corresponding intravascular ultrasound images and ECG signals, and the ultrasound device continuously acquires the intravascular ultrasound images.

[0168] Exemplarily, the target angiographic image is acquired by an angiographic device; the program instructions, when executed, for determining the diastolic waveform-free interval within the target subject's cardiac cycle include: receiving the target subject's electrocardiographic signal from an electrocardiographic device; and identifying the diastolic waveform-free interval based on the electrocardiographic signal. The program instructions, when executed, are further configured to: control the angiographic device to begin acquiring coronary angiographic images upon identifying the start of the diastolic waveform-free interval; and control the angiographic device to stop acquiring coronary angiographic images upon identifying the end of the diastolic waveform-free interval. The program instructions, when executed, for acquiring a target ultrasound image of a target blood vessel of the target subject within the diastolic waveform-free interval include: selecting at least two frames of angiographic images at different angiographic angles from among the coronary angiographic images acquired by the angiographic device as target angiographic images.

[0169] Exemplarily, the target angiographic image is acquired by an angiography device; the steps executed by the program instructions during execution for determining the diastolic waveform-free interval within the cardiac cycle of the target subject include: receiving the target subject's electrocardiographic signal from an electrocardiogram device; identifying the diastolic waveform-free interval based on the electrocardiogram signal; and the steps executed by the program instructions during execution for acquiring the target angiographic image of the target vessel of the target subject during the diastolic waveform-free interval include: based on the identified diastolic waveform-free interval, selecting at least two candidate coronary angiography images at different angiography angles from among the coronary angiography images acquired by the angiography device as the target angiography images. The candidate coronary angiography images are coronary angiography images acquired by the angiography device during the diastolic waveform-free interval. The angiography device and the electrocardiogram device synchronously acquire their respective coronary angiography images and electrocardiogram signals, and the angiography device continuously acquires the coronary angiography images.

[0170] Illustratively, the steps of identifying diastolic waveform-free intervals based on ECG signals executed by the program instructions during execution include the following operations: Calculating instantaneous resistance at each moment in the cardiac cycle based on waveform amplitude characteristics of the ECG signal; Determining diastolic waveform-free intervals based on the instantaneous resistance at each moment in the cardiac cycle.

[0171] Exemplarily, the program instructions used to perform blood vessel reconstruction based on the target ultrasound image and the target angiography image during execution, and the steps of generating a blood vessel model of the target blood vessel include: identifying the centerline of the target blood vessel from the target angiography image; identifying the lumen contour of the target blood vessel from the target ultrasound image; and aligning and reconstructing the lumen contour along the centerline to obtain a blood vessel model.

[0172] Exemplarily, before the program instructions, when executed, perform the step of registering and reconstructing the lumen contour along the centerline to obtain a blood vessel model, the program instructions, when executed, further perform the step of identifying side branches of the target blood vessel from the target ultrasound image. The step of registering and reconstructing the lumen contour along the centerline to obtain a blood vessel model, when executed, includes registering and reconstructing the side branches along the centerline with the lumen contour.

[0173] Exemplarily, a target ultrasound image is acquired by an ultrasound device; the ultrasound device includes an ultrasound catheter and an ultrasound transducer disposed on the ultrasound catheter; the ultrasound transducer is configured to acquire an ultrasound image of a target subject's blood vessel during retraction of the ultrasound catheter; and the program instructions, when executed, perform the following steps to identify the centerline of the target blood vessel from the target angiography image. For each coronary angiography frame in the target angiography image, a retraction start point and a retraction end point of the ultrasound catheter in the coronary angiography image are determined. Based on the retraction start point and the retraction end point, a retraction path of the ultrasound catheter is extracted from the coronary angiography image. Based on the retraction path corresponding to each coronary angiography frame in the target angiography image, a three-dimensional retraction path of the ultrasound catheter is generated. The centerline of the target blood vessel is represented by the three-dimensional retraction path.

[0174] Exemplarily, the steps of extracting the retraction path of the ultrasound catheter from the coronary angiography image based on the retraction start point and the retraction end point executed by the program instructions during execution include the following operations. The coronary angiography image is preprocessed to obtain a preprocessed coronary angiography image. The preprocessing includes filtering and / or histogram enhancement processing. The target blood vessels in the preprocessed coronary angiography image are enhanced to obtain a boundary-enhanced coronary angiography image. The boundary-enhanced coronary angiography image is binarized and morphologically denoised to obtain a processed coronary angiography image. The shortest path starting from the retraction start point and ending at the retraction end point is extracted from the processed coronary angiography image as the retraction path.

[0175] Exemplarily, the vascular parameters include the cross-sectional area corresponding to each point on the long axis of the vascular model, and the steps for determining the blood flow reserve fraction of the target vessel based on the vascular parameters in the vascular model executed by the program instructions during execution include: determining the stenotic vessel segment and the normal vessel segment in the vascular model based on the size of the cross-sectional area corresponding to each point on the long axis of the vascular model; obtaining the mean arterial pressure of the target vessel; determining the pressure difference corresponding to the stenotic vessel segment based on the cross-sectional area corresponding to the stenotic vessel segment, the cross-sectional area corresponding to the normal vessel segment, and the length of the stenotic vessel segment; and determining the blood flow reserve fraction of the target vessel based on the mean arterial pressure and the pressure difference.

[0176] A person skilled in the art can understand the specific implementation of the electronic device and the non-volatile storage medium by reading the above description of the method for determining the blood flow reserve fraction. For the sake of brevity, it is not described here in detail.

[0177] 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 application. Various changes and modifications may be made therein by those skilled in the art without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0178] 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. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0179] In the several embodiments provided in this application, 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 function division. In actual implementation, other division methods may be used, such as combining or integrating multiple units or components into another device, or ignoring or not performing some features.

[0180] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can 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.

[0181] Similarly, it should be understood that in order to streamline the present application and aid in understanding one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, this approach of the present application should not be interpreted as reflecting the intention that the application claimed for protection 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 application.

[0182] Those skilled in the art will understand 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.

[0183] 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 this application and to form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

[0184] The various component embodiments of the present application 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 the vascular imaging device and electronic device according to the embodiments of the present application. The present application 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 implementing the present application 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.

[0185] It should be noted that the above embodiments illustrate rather than limit the present application, and that a person skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbols 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 application may be implemented by means of hardware comprising several different elements and by means of appropriately programmed computers. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0186] The above description is merely a specific embodiment or illustration of a specific embodiment of the present application, and the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. The scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A vascular imaging system, characterized in that: include: Ultrasound equipment for acquiring intravascular ultrasound images of a target object; Angiography equipment, used for acquiring coronary angiography images of the target object; A processing device, connected to the ultrasound device and the imaging device respectively, for: determining a diastolic waveform-free interval within a cardiac cycle of the target subject; Acquire a target ultrasound image and a target angiography image of a target blood vessel of the target object in the diastolic waveform-free interval from the images acquired by the ultrasound device and the angiography device respectively; Performing blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel; Based on the blood vessel parameters in the blood vessel model, a blood flow reserve fraction of the target blood vessel is determined.

2. The vascular imaging system according to claim 1, characterized in that: The vascular imaging system further includes an electrocardiogram device for collecting electrocardiogram signals of the target object, and the processing device is connected to the electrocardiogram device, wherein: The processing device determines the diastolic waveform-free interval in the cardiac cycle of the target subject by: receiving an electrocardiogram signal of the target subject from the electrocardiogram device; Identifying the diastolic waveform-free interval based on the electrocardiogram signal; The processing device is also used for: When the start time of the diastolic waveform-free interval is identified, controlling the ultrasound device to start acquiring intravascular ultrasound images; When the end time of the diastolic waveform-free interval is identified, controlling the ultrasound device to stop acquiring the intravascular ultrasound image; The processing device acquires a target ultrasound image of a target blood vessel of the target object in the diastolic waveform-free interval from the image acquired by the ultrasound device in the following manner: An intravascular ultrasound image acquired by the ultrasound device is acquired as the target ultrasound image.

3. The vascular imaging system according to claim 1, wherein: The vascular imaging system further includes an electrocardiogram device for collecting electrocardiogram signals of the target object, and the processing device is connected to the electrocardiogram device, wherein: The processing device determines the diastolic waveform-free interval in the cardiac cycle of the target subject by: receiving an electrocardiogram signal of the target subject from the electrocardiogram device; Identifying the diastolic waveform-free interval based on the electrocardiogram signal; The processing device acquires a target ultrasound image of a target blood vessel of the target object in the diastolic waveform-free interval from the image acquired by the ultrasound device in the following manner: Selecting the target ultrasound image from the intravascular ultrasound images acquired by the ultrasound device based on the identified diastolic waveform-free interval; The ultrasound device and the electrocardiogram device synchronously acquire their respective corresponding intravascular ultrasound images and electrocardiogram signals, and the ultrasound device continuously acquires intravascular ultrasound images.

4. The vascular imaging system according to claim 1, wherein: The vascular imaging system further includes an electrocardiogram device for collecting electrocardiogram signals of the target object, and the processing device is connected to the electrocardiogram device. The processing device determines the diastolic waveform-free interval in the cardiac cycle of the target subject by: receiving an electrocardiogram signal of the target subject from the electrocardiogram device; Identifying the diastolic waveform-free interval based on the electrocardiogram signal; The processing device is also used for: When the start time of the diastolic waveform-free interval is identified, the angiography device is controlled to start collecting coronary artery Contrast images; When the end time of the diastolic waveform-free interval is identified, controlling the angiography device to stop acquiring the coronary angiography image; The processing device acquires a target angiography image of a target blood vessel of the target object in the diastolic waveform-free interval from the image acquired by the angiography device in the following manner: At least two frames of coronary angiography images at different angiography angles are selected from the coronary angiography images acquired by the angiography device as the target angiography images.

5. The vascular imaging system according to claim 1, wherein: The vascular imaging system further includes an electrocardiogram device for collecting electrocardiogram signals of the target object, and the processing device is connected to the electrocardiogram device. The processing device determines the diastolic waveform-free interval in the cardiac cycle of the target subject by: receiving an electrocardiogram signal of the target subject from the electrocardiogram device; Identifying the diastolic waveform-free interval based on the electrocardiogram signal; The processing device acquires a target angiography image of a target blood vessel of the target object in the diastolic waveform-free interval from the image acquired by the angiography device in the following manner: Based on the identified diastolic waveform-free interval, selecting at least two frames of candidate coronary angiography images at different angiography angles from the coronary angiography images acquired by the angiography device as the target angiography images; Wherein, the candidate coronary angiography image is a coronary angiography image acquired by the angiography device during the diastolic waveform-free interval; The angiography device and the electrocardiogram device synchronously acquire corresponding coronary angiography images and electrocardiogram signals, and the angiography device continuously acquires coronary angiography images.

6. The vascular imaging system according to any one of claims 2 to 5, characterized in that: The processing device identifies the diastolic waveform-free interval based on the electrocardiogram signal in the following manner: Calculating the instantaneous resistance at each moment in the cardiac cycle based on the waveform amplitude characteristics of the electrocardiogram signal; The diastolic waveform-free interval is determined based on the instantaneous resistance at each moment in the cardiac cycle.

7. The vascular imaging system according to any one of claims 1 to 5, characterized in that: The processing device performs blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel in the following manner: identifying a centerline of the target blood vessel from the target angiography image; identifying a lumen contour of the target blood vessel from the target ultrasound image; The lumen contour is registered and reconstructed along the center line to obtain the blood vessel model.

8. The vascular imaging system according to claim 7, characterized in that: The processing device is also used to: identify side branches of the target blood vessel from the target ultrasound image; The processing device registers and reconstructs the lumen contour along the center line to obtain the blood vessel model in the following manner: The side branches are registered and reconstructed together with the lumen contour along the center line.

9. The vascular imaging system according to claim 7, characterized in that: The ultrasound device comprises an ultrasound catheter and an ultrasound transducer arranged on the ultrasound catheter; the ultrasound transducer is used to collect an intravascular ultrasound image of the target object during the withdrawal of the ultrasound catheter; the processing device identifies the centerline of the target blood vessel from the target angiography image in the following manner: For each frame of coronary angiography image in the target angiography image, Determining a withdrawal starting point and a withdrawal end point of the ultrasound catheter in the coronary angiography image; Extracting a withdrawal path of the ultrasound catheter from the coronary angiography image based on the withdrawal starting point and the withdrawal end point; generating a three-dimensional retraction path of the ultrasound catheter based on the retraction path corresponding to each frame of the coronary angiography image in the target angiography image; Wherein, the centerline of the target blood vessel is represented by the three-dimensional retracement path.

10. The vascular imaging system according to claim 9, characterized in that: The processing device extracts the withdrawal path of the ultrasound catheter from the coronary angiography image based on the withdrawal starting point and the withdrawal end point in the following manner: Preprocessing the coronary angiography image to obtain a preprocessed coronary angiography image, wherein the preprocessing includes filtering and / or histogram enhancement processing; Performing blood vessel boundary enhancement on the target blood vessel in the preprocessed coronary angiography image to obtain a boundary-enhanced coronary angiography image; Performing image binarization and morphological denoising processing on the boundary-enhanced coronary angiography image to obtain a processed coronary angiography image; The shortest path starting from the retrieval starting point and ending at the retrieval end point is extracted from the processed coronary angiography image as the retrieval path.

11. The vascular imaging system according to any one of claims 1 to 5, characterized in that: The blood vessel parameters include the cross-sectional areas corresponding to each point of the long axis of the blood vessel model. The processing device determines the blood flow reserve fraction of the target blood vessel based on the blood vessel parameters in the blood vessel model in the following manner: Determining a stenotic blood vessel segment and a normal blood vessel segment in the blood vessel model based on the size of the cross-sectional area corresponding to each point on the long axis of the blood vessel model; obtaining a mean arterial pressure of the target blood vessel; determining a pressure difference corresponding to the stenotic blood vessel segment based on a cross-sectional area corresponding to the stenotic blood vessel segment, a cross-sectional area corresponding to the normal blood vessel segment, and a length of the stenotic blood vessel segment; Based on the mean arterial pressure and the pressure difference, a fractional flow reserve of the target blood vessel is determined.

12. A vascular imaging method, characterized in that: include: determining a diastolic waveform-free interval within a cardiac cycle of the target subject; Acquire a target ultrasound image and a target contrast image of a target blood vessel of the target object in the diastolic waveform-free interval from images acquired by an ultrasound device and a contrast imaging device respectively; Performing blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel; Based on the blood vessel parameters in the blood vessel model, a blood flow reserve fraction of the target blood vessel is determined.

13. The blood vessel imaging method according to claim 12, characterized in that: The step of determining the diastolic waveform-free interval in the cardiac cycle of the target object comprises: receiving an electrocardiogram signal of the target object from an electrocardiogram device; Identifying the diastolic waveform-free interval based on the electrocardiogram signal; The method further comprises: When the start time of the diastolic waveform-free interval is identified, controlling the ultrasound device to start acquiring intravascular ultrasound images; When the end time of the diastolic waveform-free interval is identified, controlling the ultrasound device to stop acquiring the intravascular ultrasound image; The step of acquiring a target ultrasound image of a target blood vessel of the target object in the diastolic waveform-free interval from an image acquired by an ultrasound device includes: An intravascular ultrasound image acquired by the ultrasound device is acquired as the target ultrasound image.

14. The blood vessel imaging method according to claim 12, characterized in that: The step of determining the diastolic waveform-free interval in the cardiac cycle of the target object comprises: receiving an electrocardiogram signal of the target subject from an electrocardiogram device; Identifying the diastolic waveform-free interval based on the electrocardiogram signal; The step of acquiring a target ultrasound image of a target blood vessel of the target object in the diastolic waveform-free interval from an image acquired by an ultrasound device includes: Selecting the target ultrasound image from the intravascular ultrasound images acquired by the ultrasound device based on the identified diastolic waveform-free interval; The ultrasound device and the electrocardiogram device synchronously acquire their respective corresponding intravascular ultrasound images and electrocardiogram signals, and the ultrasound device continuously acquires intravascular ultrasound images.

15. The blood vessel imaging method according to claim 12, characterized in that: The step of determining the diastolic waveform-free interval in the cardiac cycle of the target object comprises: receiving an electrocardiogram signal of the target subject from an electrocardiogram device; Identifying the diastolic waveform-free interval based on the electrocardiogram signal; The method further comprises: When the start time of the diastolic waveform-free interval is identified, controlling the angiography device to start collecting coronary angiography images; When the end time of the diastolic waveform-free interval is identified, controlling the angiography device to stop acquiring the coronary angiography image; The step of acquiring a target angiography image of a target blood vessel of the target object in the diastolic waveform-free interval from an image acquired by an angiography device comprises: At least two frames of coronary angiography images at different angiography angles are selected from the coronary angiography images acquired by the angiography device as the target angiography images.

16. The blood vessel imaging method according to claim 12, characterized in that: The step of determining the diastolic waveform-free interval in the cardiac cycle of the target object comprises: receiving an electrocardiogram signal of the target subject from an electrocardiogram device; Identifying the diastolic waveform-free interval based on the electrocardiogram signal; The step of acquiring a target angiography image of a target blood vessel of the target object in the diastolic waveform-free interval from an image acquired by an angiography device comprises: Based on the identified diastolic waveform-free interval, selecting at least two frames of candidate coronary angiography images at different angiography angles from the coronary angiography images acquired by the angiography device as the target angiography images; Wherein, the candidate coronary angiography image is a coronary angiography image acquired by the angiography device during the diastolic waveform-free interval; The angiography device and the electrocardiogram device synchronously acquire corresponding coronary angiography images and electrocardiogram signals, and the angiography device continuously acquires coronary angiography images.

17. The vascular imaging method according to any one of claims 13 to 16, characterized in that: The step of identifying the diastolic waveform-free interval based on the electrocardiogram signal comprises: Calculating the instantaneous resistance at each moment in the cardiac cycle based on the waveform amplitude characteristics of the electrocardiogram signal; The diastolic waveform-free interval is determined based on the instantaneous resistance at each moment in the cardiac cycle.

18. The vascular imaging method according to any one of claims 12 to 16, characterized in that: The step of performing blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel includes: identifying a centerline of the target blood vessel from the target angiography image; identifying a lumen contour of the target blood vessel from the target ultrasound image; The lumen contour is registered and reconstructed along the center line to obtain the blood vessel model.

19. The blood vessel imaging method according to claim 18, characterized in that: Before registering and reconstructing the lumen contour along the center line to obtain the blood vessel model, reconstructing the blood vessel based on the target ultrasound image and the target angiography image to generate the blood vessel model of the target blood vessel further includes: identifying a side branch of the target blood vessel from the target ultrasound image; The step of registering and reconstructing the lumen contour along the center line to obtain the blood vessel model comprises: The side branches are registered and reconstructed together with the lumen contour along the centerline.

20. The blood vessel imaging method according to claim 18, characterized in that: The ultrasound device comprises an ultrasound catheter and an ultrasound transducer arranged on the ultrasound catheter; the ultrasound transducer is used to collect an intravascular ultrasound image of the target object during the withdrawal of the ultrasound catheter; and the identifying the centerline of the target blood vessel from the target angiography image comprises: For each frame of coronary angiography image in the target angiography image, Determining a withdrawal starting point and a withdrawal end point of the ultrasound catheter in the coronary angiography image; Extracting a withdrawal path of the ultrasound catheter from the coronary angiography image based on the withdrawal starting point and the withdrawal end point; generating a three-dimensional retraction path of the ultrasound catheter based on the retraction path corresponding to each frame of the coronary angiography image in the target angiography image; Wherein, the centerline of the target blood vessel is represented by the three-dimensional retracement path.

21. The blood vessel imaging method according to claim 20, characterized in that: The step of extracting the withdrawal path of the ultrasound catheter from the coronary angiography image based on the withdrawal starting point and the withdrawal end point includes: Preprocessing the coronary angiography image to obtain a preprocessed coronary angiography image, wherein the preprocessing includes filtering and / or histogram enhancement processing; Performing blood vessel boundary enhancement on the target blood vessel in the preprocessed coronary angiography image to obtain a boundary-enhanced coronary angiography image; Performing image binarization and morphological denoising processing on the boundary-enhanced coronary angiography image to obtain a processed coronary angiography image; The shortest path starting from the retrieval starting point and ending at the retrieval end point is extracted from the processed coronary angiography image as the retrieval path.

22. The vascular imaging method according to any one of claims 12 to 16, characterized in that: The vascular parameters include the cross-sectional areas corresponding to each point of the long axis of the vascular model; and determining the blood flow reserve fraction of the target blood vessel based on the vascular parameters in the vascular model includes: Determining a stenotic blood vessel segment and a normal blood vessel segment in the blood vessel model based on the size of the cross-sectional area corresponding to each point on the long axis of the blood vessel model; obtaining a mean arterial pressure of the target blood vessel; determining a pressure difference corresponding to the stenotic blood vessel segment based on a cross-sectional area corresponding to the stenotic blood vessel segment, a cross-sectional area corresponding to the normal blood vessel segment, and a length of the stenotic blood vessel segment; Based on the mean arterial pressure and the pressure difference, a fractional flow reserve of the target blood vessel is determined.

23. A vascular imaging device, characterized in that: include: A first determination module is used to determine a diastolic waveform-free interval in a cardiac cycle of a target object; An acquisition module, configured to respectively acquire a target ultrasound image and a target angiography image of a target blood vessel of the target object in the diastolic waveform-free interval from images acquired by an ultrasound device and an angiography device respectively; A blood vessel reconstruction module, used for performing blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel; The second determination module is used to determine the blood flow reserve fraction of the target blood vessel based on the blood vessel parameters in the blood vessel model.

24. An electronic device comprising a processor and a memory, wherein: The memory stores computer program instructions, which are used by the processor to perform the following operations when executed: determining a diastolic waveform-free interval within a cardiac cycle of the target subject; Acquire a target ultrasound image and a target angiography image of a target blood vessel of the target object in the diastolic waveform-free interval; Performing blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel; Based on the blood vessel parameters in the blood vessel model, a blood flow reserve fraction of the target blood vessel is determined.

25. A computer-readable storage medium having program instructions stored thereon, the program instructions being used to perform the following operations when executed: determining a diastolic waveform-free interval within a cardiac cycle of the target subject; Acquire a target ultrasound image and a target angiography image of a target blood vessel of the target object in the diastolic waveform-free interval; Performing blood vessel reconstruction based on the target ultrasound image and the target angiography image to generate a blood vessel model of the target blood vessel; Based on the blood vessel parameters in the blood vessel model, a blood flow reserve fraction of the target blood vessel is determined.

Images