Method and device for calculating blood flow at any position of blood vessel tree

Abstract

The present invention relates to the technical field of medical image processing, and disclosed are a method and device for calculating blood flow at any position of a blood vessel tree. The method comprises: acquiring angiography image sequences, and performing structure extraction on images in the angiography image sequences to obtain two-dimensional blood vessel skeleton lines; performing three-dimensional reconstruction on the basis of the two-dimensional blood vessel skeleton lines to obtain a three-dimensional blood vessel model; determining a corresponding target blood vessel area on the basis of the three-dimensional blood vessel model, and calculating corresponding average blood flow in the target blood vessel area on the basis of transfer frame quantities corresponding to the angiography image sequences; reconstructing a reference blood vessel diameter on the basis of a corresponding blood vessel diameter in the target blood vessel area, and determining a blood vessel stenosis area on the basis of the blood vessel diameter and the reference blood vessel diameter; and calculating corresponding target blood flow at a target position in the target blood vessel area on the basis of the blood vessel stenosis area and the average blood flow. According to the present invention, blood flow at any position of blood vessels can be accurately calculated.

Description

A method and apparatus for calculating blood flow at arbitrary locations in a vascular tree. Technical Field

[0001] This invention relates to the field of medical image processing technology, and in particular to a method and apparatus for calculating blood flow at any location on a vascular tree. Background Technology

[0002] Cardiovascular and cerebrovascular diseases are mainly caused by lesions such as narrowing, dilation, damage or dissection of blood vessels, leading to ischemia, blockage or hemorrhage, such as coronary artery stenosis in coronary arteries and intracranial aneurysms in cerebral blood vessels.

[0003] In clinical practice, traditional imaging techniques for diagnosing cardiovascular and cerebrovascular diseases include digital subtraction angiography (DSA), computed tomography angiography (CTA), and optical coherence tomography (OCT). Among these, DSA is an essential examination for most patients with vascular diseases.

[0004] In recent years, an increasing number of researchers have recognized the close relationship between hemodynamic characteristics and the occurrence of cardiovascular and cerebrovascular diseases, and have been assessing and diagnosing vascular diseases at the hemophysiological level based on various hemodynamic parameters. Among these, blood flow, as a crucial blood flow indicator, is not only an important assessment parameter for the diagnosis of vascular diseases but also a necessary basis for calculating other blood flow parameters.

[0005] Existing methods for calculating blood flow mainly fall into two categories: invasive measurement and non-invasive calculation. In non-invasive blood flow calculation, this technology is primarily based on DSA imaging, including:

[0006] 1. TIMI frame counting method: First, observe the number of frames that the contrast agent takes to travel from the proximal end of the blood vessel to the distal end. Multiply the number of frames by the frame transition time to obtain the contrast agent transport time. Then, divide the three-dimensional centerline length from the proximal end to the distal end by the transport time to obtain the average blood flow velocity of the entire blood vessel. The average blood flow rate is obtained by multiplying the average blood flow velocity by the cross-sectional area of ​​the blood vessel.

[0007] 2. Centerline length variation fitting method: Extract the variation sequence of the centerline length of blood vessels from the blood vessel segmentation image of the DSA sequence within a cardiac cycle, and then perform a fitting once in a time period of uniform variation. The slope of the fitted line after unit conversion is the average blood flow velocity of the blood vessel. Similarly, multiply the average blood flow velocity by the cross-sectional area of ​​the blood vessel to obtain the average blood flow rate.

[0008] 3. Perfusion area grayscale analysis method: By selecting the perfusion area of ​​the vascular tree in the DSA image as the region of interest, the grayscale change curve of the region of interest is recorded, and the area under the curve is obtained by integration, thereby obtaining the average blood flow of the vascular tree.

[0009] However, both the TIMI framing method and the centerline length variation fitting method are based on the assumption of single-vessel flow conservation, and can only calculate the average flow velocity of the entire vessel segment to obtain a single blood flow value, ignoring the problem of inconsistent flow at different locations of the vessel due to branching. Furthermore, the calculation results of the perfusion region grayscale analysis method are greatly affected by image noise and cannot automatically track the dynamic changes of the region of interest, leading to inaccurate calculation results. Therefore, existing technologies suffer from the problem of not being able to accurately calculate blood flow at arbitrary locations within a vessel. Summary of the Invention

[0010] This invention provides a method and apparatus for calculating blood flow at any location in a vascular tree, the main purpose of which is to solve the problem of being unable to accurately calculate blood flow at any location in a blood vessel.

[0011] To achieve the above objectives, the present invention provides a method for calculating blood flow at any location in a vascular tree, comprising:

[0012] A sequence of angiography images is acquired, and the structure of the images in the angiography image sequence is extracted to obtain a two-dimensional vascular skeleton line;

[0013] A three-dimensional vascular model is obtained by performing three-dimensional reconstruction based on the two-dimensional vascular skeleton lines.

[0014] The target vascular region is determined based on the three-dimensional vascular model, and the average blood flow corresponding to the target vascular region is calculated based on the number of transport frames corresponding to the angiography image sequence.

[0015] The reference diameter of the blood vessel is reconstructed based on the blood vessel diameter corresponding to the target blood vessel region, and the narrowing region of the blood vessel is determined based on the blood vessel diameter and the reference diameter of the blood vessel.

[0016] The target blood flow rate corresponding to the target location in the target blood vessel region is calculated based on the stenotic area of ​​the blood vessel and the average blood flow rate.

[0017] In one embodiment of the present invention, the step of extracting the structure from the angiography image sequence to obtain a two-dimensional vascular skeleton line includes:

[0018] Image segmentation is performed on the images in the angiography image sequence to obtain vascular images;

[0019] The blood vessel image is binarized and thinned to obtain the two-dimensional blood vessel skeleton line.

[0020] In one embodiment of the present invention, the step of performing three-dimensional reconstruction based on the two-dimensional vascular skeleton lines to obtain a three-dimensional vascular model includes:

[0021] After aligning the angiography image sequence along the time axis, a binocular vision 3D reconstruction method is used to perform matrix mapping based on the two-dimensional vascular skeleton lines to obtain the correspondence between the two-dimensional vascular skeleton lines.

[0022] Target pixels are selected one by one from the two-dimensional vascular skeleton line, and the vascular diameter corresponding to the target pixel is obtained from the images in the angiography image sequence based on the correspondence.

[0023] Construct a corresponding closed contour line of the blood vessel based on the target pixel points and the blood vessel diameter;

[0024] A three-dimensional blood vessel model is generated based on the closed contour line of the blood vessel corresponding to each pixel point on the two-dimensional blood vessel skeleton line.

[0025] In one embodiment of the present invention, calculating the average blood flow corresponding to the target vascular region based on the number of transport frames corresponding to the angiography image sequence includes:

[0026] The transport time is calculated based on the number of transport frames corresponding to the angiography image sequence.

[0027] The average blood flow velocity is calculated based on the transport time and the length of the target vascular region.

[0028] Calculate the average cross-sectional area based on the blood vessel diameter corresponding to the target blood vessel region;

[0029] The average blood flow rate is calculated based on the average blood flow velocity and the average cross-sectional area.

[0030] In one embodiment of the present invention, calculating the average blood flow velocity based on the transport time and the regional length of the target blood vessel region includes:

[0031] Obtain proximal and distal landmarks in the target vascular region;

[0032] The region length is obtained by calculating the shortest path based on the centerline between the near-end marker and the far-end marker.

[0033] The ratio of the region length to the transport time is used as the average blood flow velocity.

[0034] In one embodiment of the present invention, determining the vascular stenosis region based on the vessel diameter and the vessel reference diameter includes:

[0035] The stenosis point is determined based on the ratio of the vessel diameter to the reference vessel diameter;

[0036] Based on the blood vessel diameter and the blood vessel reference diameter, respectively, fit the diameter function and the reference diameter function corresponding to the target blood vessel region;

[0037] The vascular stenosis region is determined based on the intersection of the diameter function and the reference diameter function, as well as the stenosis point.

[0038] In one embodiment of the present invention, calculating the target blood flow corresponding to the target location in the target blood vessel region based on the vascular stenosis region and the average blood flow includes:

[0039] Calculate the average diameter of the blood vessels based on the diameter of the blood vessels in the target vascular region;

[0040] Determine whether there is a stenotic area in the target blood vessel region:

[0041] If so, the target blood flow is calculated using the first blood flow calculation formula based on the reference diameter of the blood vessel corresponding to the target location, the average diameter of the blood vessel, and the average blood flow.

[0042] If not, the target blood flow is calculated using the second blood flow calculation formula based on the blood vessel diameter corresponding to the target location, the average blood vessel diameter, and the average blood flow.

[0043] In one embodiment of the present invention, the first blood flow calculation formula is expressed as:

[0044] Where Q represents the target blood flow at the target location. The average blood flow is represented by D″, and the reference diameter of the blood vessel at the target location is represented by D″. denoted as the average diameter of the blood vessel, and b as a preset first coefficient;

[0045] The second blood flow calculation formula is expressed as follows:

[0046] Where Q represents the target blood flow at the target location. The average blood flow is represented by D, and D′ represents the diameter of the blood vessel at the target location. The value is represented by the average diameter of the blood vessel, and c is the preset second coefficient.

[0047] In one embodiment of the present invention, the number of transport frames corresponding to the angiography image sequence can be obtained through the following steps:

[0048] The length of the blood vessel from the proximal and distal markers of the target blood vessel region to the entrance of the blood vessel tree is obtained in advance.

[0049] Obtain the length of movement from the vascular tree entrance to the contrast agent movement position in the angiography image sequence;

[0050] The number of transport frames is calculated by subtracting the distance between the travel length and the blood vessel length.

[0051] To address the above problems, the present invention also provides a device for calculating blood flow at any location in a vascular tree, the device comprising:

[0052] A two-dimensional vascular skeleton line construction module is used to acquire angiography image sequences and extract the structure of the images in the angiography image sequences to obtain two-dimensional vascular skeleton lines.

[0053] The three-dimensional blood vessel model reconstruction module is used to perform three-dimensional reconstruction based on the two-dimensional blood vessel skeleton lines to obtain a three-dimensional blood vessel model.

[0054] The average blood flow calculation module is used to determine the corresponding target blood vessel region based on the three-dimensional blood vessel model, and to calculate the average blood flow corresponding to the target blood vessel region based on the number of transport frames corresponding to the angiography image sequence.

[0055] The vascular stenosis region determination module is used to reconstruct the vascular reference diameter based on the vascular diameter corresponding to the target vascular region, and to determine the vascular stenosis region based on the vascular diameter and the vascular reference diameter.

[0056] The target blood flow calculation module is used to calculate the target blood flow corresponding to the target location in the target blood vessel region based on the stenotic region of the blood vessel and the average blood flow.

[0057] This invention extracts two-dimensional vascular skeleton lines and reconstructs three-dimensional vessels based on angiographic image sequences, achieving efficient and accurate generation of three-dimensional vascular models. By reconstructing the vascular reference diameter from the 3D vascular model's diameter, the efficiency of obtaining the vascular reference diameter is improved. Furthermore, by reconstructing the vascular reference diameter based on the vascular diameter, stenosis regions can be identified, accurately determining the stenosis area and its degree within the target vascular region. Based on the stenosis region, the target blood flow corresponding to the target location within the target vascular region is calculated, enabling the calculation of blood flow at any location within the vessel and improving the accuracy of blood flow calculation. Therefore, the method and apparatus for calculating blood flow at any location in the vascular tree proposed in this invention can solve the problem of inaccurately calculating blood flow at any location within a vessel. Attached Figure Description

[0058] Figure 1 is a flowchart illustrating a method for calculating blood flow at any location in a vascular tree according to an embodiment of the present invention.

[0059] Figure 2 is a schematic diagram of the fitting curves of the blood vessel diameter function and the blood vessel reference diameter function provided in an embodiment of the present invention;

[0060] Figure 3 is a functional block diagram of a device for calculating blood flow at any position in a vascular tree according to an embodiment of the present invention;

[0061] Figure 4 is a schematic diagram of the structure of an electronic device that implements the method for calculating blood flow at any position of the vascular tree according to an embodiment of the present invention.

[0062] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0063] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0064] This application provides a method for calculating blood flow at any location on a vascular tree. The execution subject of this method includes, but is not limited to, at least one of the following electronic devices that can be configured to execute the method provided in this application: a server, a terminal, etc. In other words, the method for calculating blood flow at any location on a vascular tree can be executed by software or hardware installed on a terminal device or a server device.

[0065] Referring to Figure 1, this is a flowchart illustrating a method for calculating blood flow at any location on a vascular tree according to an embodiment of the present invention. In this embodiment, the method for calculating blood flow at any location on a vascular tree includes:

[0066] S1. Obtain angiography image sequence and extract the structure of the images in the angiography image sequence to obtain two-dimensional vascular skeleton lines.

[0067] In this embodiment of the invention, the angiography image sequence includes angiography image sequences from at least two angles. Taking angiography image sequences from two angles as an example, the angle difference between the imaging angles of the two angiography image sequences can be greater than 30 degrees, and the angle with the least cross-obstruction of the target blood vessel and clear imaging is selected.

[0068] In the angiography image sequence, the blood vessels in the images are represented in the form of a vascular tree. A vascular tree is a tree-like vascular network that includes main trunk vessels and branch vessels, or only main trunk vessels (single branch tree), such as coronary artery tree, intracranial artery vascular tree, portal vein vascular tree, etc.

[0069] In detail, the angiography image sequence is a DSA image file, and the image file format is DICOM. This format stores image data and header data containing information such as shooting frame rate, imaging information, window width, and window level. The angiography image sequence consists of many image frames arranged in chronological order. The angiography image sequence records the dynamic information of the contrast agent's transport process in the blood vessel. The images in the angiography image sequence are obtained by X-ray imaging after the contrast agent is introduced into the blood vessel through the contrast catheter during digital subtraction angiography (DSA) examination.

[0070] In this embodiment of the invention, the step of extracting the structure from the angiography image sequence to obtain a two-dimensional vascular skeleton line includes:

[0071] Image segmentation is performed on the images in the angiography image sequence to obtain vascular images;

[0072] The blood vessel image is binarized and thinned to obtain the two-dimensional blood vessel skeleton line.

[0073] In detail, the purpose of vessel segmentation is to separate the contrast-filled vessel regions from the background in each frame of an angiographic image sequence, resulting in a continuous two-dimensional vessel image. Specifically, vessel segmentation can be achieved using thresholding, separating vessels from the background based on one or more thresholds; alternatively, region growing algorithms can be used to merge adjacent regions based on the similarity of neighboring pixels; or deep learning methods, such as convolutional neural networks (CNNs), can be employed to learn image features and achieve automatic vessel segmentation.

[0074] Furthermore, based on a refined skeleton extraction algorithm, morphological operations can be iteratively applied to continuously subtract elements from the binary image that do not change the image topology, refining it until the image no longer changes, resulting in a two-dimensional vascular skeleton line with a width of only one pixel; wherein, the two-dimensional vascular skeleton line is the center line of the vascular image.

[0075] S2. Perform three-dimensional reconstruction based on the two-dimensional vascular skeleton lines to obtain a three-dimensional vascular model.

[0076] In one optional embodiment of the present invention, the vascular skeleton extraction operation can be performed on each image in the angiography image sequence, or the vascular skeleton extraction can be performed on a moment or several frames in the angiography image sequence where the blood vessels are fully visualized, the cross-obstruction is minimal, and the contrast agent is abundant.

[0077] In this embodiment of the invention, the step of performing three-dimensional reconstruction based on the two-dimensional vascular skeleton lines to obtain a three-dimensional vascular model includes:

[0078] After aligning the angiography image sequence along the time axis, a binocular vision 3D reconstruction method is used to perform matrix mapping based on the two-dimensional vascular skeleton lines to obtain the correspondence between the two-dimensional vascular skeleton lines.

[0079] Target pixels are selected one by one from the two-dimensional vascular skeleton line, and the vascular diameter corresponding to the target pixel is obtained from the images in the angiography image sequence based on the correspondence.

[0080] Construct a corresponding closed contour line of the blood vessel based on the target pixel points and the blood vessel diameter;

[0081] A three-dimensional blood vessel model is generated based on the closed contour line of the blood vessel corresponding to each pixel point on the two-dimensional blood vessel skeleton line.

[0082] In detail, this invention aligns angiographic image sequences from different angles on the time axis to ensure that two frames of vascular images at the same cardiac phase from different angles are located at the same moment on the time axis. Furthermore, when the angiographic image sequence contains ECG-gated data, phase alignment is automatically performed based on the ECG-gated data; if it does not contain ECG-gated data, phase adjustment alignment is performed based on the phase difference between the angiographic image sequences from different angles.

[0083] In this embodiment of the invention, taking angiography image sequences from two angles as an example, the pixels in the angiography image sequence should meet the following requirements: Where X1 is the pixel coordinates on the two-dimensional vascular skeleton line at one angle, X2 is the pixel coordinates on the two-dimensional vascular skeleton line at another angle, and F represents the basic matrix: Where R represents the rotation matrix, which represents the rotation angle of the C-arm of the imaging system, and t represents the translation matrix, which is used to represent the translation vector of the imaged object.

[0084] Specifically, the rotation matrix can be a 3*3 matrix, and the translation matrix can be a 3*1 matrix.

[0085] Since the imaging of contrast images uses X-ray transmission imaging, K1 and K2 represent the intrinsic parameter matrices of the imaging system at two angles, determined by the projection parameters of the X-ray system:

[0086] Where SID is the distance from the X-ray source to the imaging plate, SOD is the distance from the X-ray source to the object being imaged, and p x and p y These are the physical dimensions of a pixel in the x and y directions on the image plane, respectively.x c y () is the coordinate point of the X-ray source center on the imaging plate.

[0087] The present invention calculates the basic matrix F using the above formula, thereby obtaining the correspondence between pixels on the two-dimensional vascular skeleton line at two angles, and then reconstructing the three-dimensional vascular tree skeleton line.

[0088] In this embodiment of the invention, the two-dimensional blood vessel diameter corresponding to the target pixel can be determined in the images of the angiography image sequence at different angles based on the correspondence between pixels on the two-dimensional blood vessel skeleton line. The two-dimensional blood vessel diameter corresponding to different angles can be set with different weights. By multiplying the two-dimensional blood vessel diameter with the corresponding weight and then summing them, the blood vessel diameter corresponding to the target pixel can be obtained.

[0089] Furthermore, based on the assumption of a circular cross section, a circular outline corresponding to the target pixel can be drawn according to the target pixel and the diameter of the blood vessel, that is, the closed outline of the blood vessel; the blood vessel surface is enclosed by a cylindrical surface between adjacent outlines, thus obtaining a three-dimensional blood vessel model.

[0090] S3. Determine the corresponding target blood vessel region based on the three-dimensional blood vessel model, and calculate the average blood flow corresponding to the target blood vessel region based on the number of transport frames corresponding to the angiography image sequence.

[0091] In a practical application scenario of the present invention, the target blood vessel region can be determined by the operator when observing the angiography image sequence, by selecting the entrance and exit of the target blood vessel region in the image, and then determining the target blood vessel region for blood flow analysis in the three-dimensional blood vessel model; wherein, the aforementioned entrance and exit are the proximal and distal landmarks of the target blood vessel region.

[0092] In this embodiment of the invention, calculating the average blood flow corresponding to the target blood vessel region based on the number of transport frames corresponding to the angiography image sequence includes:

[0093] The transport time is calculated based on the number of transport frames corresponding to the angiography image sequence.

[0094] The average blood flow velocity is calculated based on the transport time and the length of the target vascular region.

[0095] Calculate the average cross-sectional area based on the blood vessel diameter corresponding to the target blood vessel region;

[0096] The average blood flow rate is calculated based on the average blood flow velocity and the average cross-sectional area.

[0097] In this embodiment of the invention, calculating the average blood flow velocity based on the transport time and the regional length of the target blood vessel region includes:

[0098] Obtain proximal and distal landmarks in the target vascular region;

[0099] The region length is obtained by calculating the shortest path based on the centerline between the near-end marker and the far-end marker.

[0100] The ratio of the region length to the transport time is used as the average blood flow velocity.

[0101] In this embodiment of the invention, since the center line of the target blood vessel region is formed by connecting individual pixels, the shortest path algorithm can be used to extract the blood vessel center line between the proximal and distal marker points, and the length of the center line can be calculated as the region length of the target blood vessel region.

[0102] Specifically, the method for calculating the centerline length is as follows: L=∑l j

[0103] Among them, (x A ,y A ,z A ), (x B ,y B ,z B ) represents the coordinates of two adjacent pixels on the center line between near-end marker A and far-end marker B. j L represents the distance between the coordinates of the j-th pair of adjacent pixels, and L represents the length of the region, which is the sum of the distances between all two adjacent pixels on the center line between the near and far markers.

[0104] In this embodiment of the invention, the number of transport frames corresponding to the angiography image sequence can be obtained through the following steps:

[0105] The length of the blood vessel from the proximal and distal markers of the target blood vessel region to the entrance of the blood vessel tree is obtained in advance.

[0106] Obtain the length of movement from the vascular tree entrance to the contrast agent movement position in the angiography image sequence;

[0107] The number of transport frames is calculated by subtracting the distance between the travel length and the blood vessel length.

[0108] Specifically, the shortest path method can be used to extract the centerline length s1 from the entrance of the target blood vessel region to the entrance of the vascular tree when the contrast agent is filled into the blood vessel, and to extract the centerline length s2 from the exit of the blood vessel segment to the entrance of the vascular tree.

[0109] During the stage from the initial injection of contrast agent into the blood vessel to the filling of the entire vascular tree, the length S of the centerline from the vascular tree inlet to the tip of the main blood vessel containing the target vascular region is extracted from each frame of the angiography image sequence. i ;

[0110] By calculating Min(S) i -s1) Find the appropriate S i The time frame F′ corresponding to the minimum difference with s1 is calculated similarly to Min(S). i -s2) Find the appropriate S i The time frame F″ corresponding to the smallest difference from s2 is used to calculate the number of contrast agent transport frames F based on the difference between time frame F′ and time frame F″.

[0111] Furthermore, taking angiography image sequences from two different angles as an example, the corresponding transport frame numbers F1 and F2 are obtained respectively. The transport time can be calculated using the following formula to reduce the error in transport time calculation:

[0112] Where F1 represents the number of transport frames corresponding to the angiography image sequence at the first angle, F2 represents the number of transport frames corresponding to the angiography image sequence at another angle, and f is the image capture frequency in the angiography image sequence.

[0113] In this embodiment of the invention, the average cross-sectional area is obtained by calculating the diameter of the target blood vessel region in the three-dimensional blood vessel model using the following formula:

[0114] Among them, A k This is represented as the cross-sectional area of ​​the blood vessel corresponding to the k-th pixel in the target blood vessel region. D is represented as the average cross-sectional area. k Let represent the diameter of the blood vessel corresponding to the k-th pixel in the target blood vessel region, and n represent the total number of pixels in the target blood vessel region;

[0115] The average blood flow rate of the target vascular region can be obtained by multiplying the average blood flow velocity by the average cross-sectional area.

[0116] S4. Reconstruct the reference diameter of the blood vessel based on the blood vessel diameter corresponding to the target blood vessel region, and determine the stenotic region of the blood vessel based on the blood vessel diameter and the reference diameter of the blood vessel.

[0117] Referring to Figure 2, in this embodiment of the invention, the step of reconstructing the blood vessel reference diameter based on the blood vessel diameter corresponding to the target blood vessel region includes:

[0118] The parent and daughter blood vessels are determined based on the target vascular region and the three-dimensional vascular model.

[0119] The first interface diameter between the daughter vessel and the mother vessel is obtained based on the vessel diameter, and the second interface diameter of the mother vessel is corrected based on the diameter of the daughter vessel and the first interface diameter to obtain the corrected interface diameter.

[0120] The reference diameter of the blood vessel corresponding to the target blood vessel region is generated based on the diameter of the first interface and the diameter of the modified interface.

[0121] Specifically, according to the modified Murray's law, in a vascular tree, the diameter of the parent vessel... The power equals the diameter of the sub-vessel. The sum of powers, therefore, the diameter of the second interface can be corrected using the following formula:

[0122] Where D represents the diameter of the first interface, D1 represents the diameter of the sub-vessel, D2 represents the diameter of the correction interface, and a represents the preset correction coefficient, where a can be 7 / 3.

[0123] Referring to Figure 2, for the target vascular region, there are two branch vessels. The target vascular region is regarded as the parent vessel, and the branch vessels are regarded as daughter vessels. For the first daughter vessel, there are two diameters at its interface with the parent vessel. The diameter at the front end is the first interface diameter, and the diameter at the rear end is the second interface diameter that needs to be corrected. Using the above formula, the corrected interface diameter of the parent vessel at the interface is calculated based on the diameter of the first daughter vessel and the diameter of the first interface. Similarly, the corrected interface diameter of the parent vessel at the corresponding interface can be calculated based on the second daughter vessel using the above method.

[0124] Furthermore, the reference diameter between branches is linearly reduced, and the rate of change is obtained by linear fitting of the corrected diameter between the two branches. By fitting a function based on the first interface diameter of each sub-vessel and the corrected interface diameter of the parent vessel, the reference diameter of the vessel corresponding to each position in the target vessel region can be obtained.

[0125] In this embodiment of the invention, determining the vascular stenosis region based on the vessel diameter and the vessel reference diameter includes:

[0126] The stenosis point is determined based on the ratio of the vessel diameter to the reference vessel diameter;

[0127] Based on the blood vessel diameter and the blood vessel reference diameter, respectively, fit the diameter function and the reference diameter function corresponding to the target blood vessel region;

[0128] The vascular stenosis region is determined based on the intersection of the diameter function and the reference diameter function, as well as the stenosis point.

[0129] Specifically, the stenosis is calculated based on the ratio of the vessel diameter to the reference vessel diameter. Locations with a diameter stenosis greater than 25% can be identified as specific stenosis. If the stenosis point is in the region formed by the intersection of the diameter function and the reference diameter function, the region can be regarded as the vascular stenosis region, and the corresponding intersection is the start and end point of the vascular stenosis region.

[0130] S5. Calculate the target blood flow corresponding to the target location in the target blood vessel region based on the stenotic area of ​​the blood vessel and the average blood flow.

[0131] In this embodiment of the invention, calculating the target blood flow corresponding to the target location in the target blood vessel region based on the vascular stenosis region and the average blood flow includes:

[0132] Calculate the average diameter of the blood vessels based on the diameter of the blood vessels in the target vascular region;

[0133] Determine whether there is a stenotic area in the target blood vessel region:

[0134] If so, the target blood flow is calculated using the first blood flow calculation formula based on the reference diameter of the blood vessel corresponding to the target location, the average diameter of the blood vessel, and the average blood flow.

[0135] If not, the target blood flow is calculated using the second blood flow calculation formula based on the blood vessel diameter corresponding to the target location, the average blood vessel diameter, and the average blood flow.

[0136] Specifically, due to the continuity of blood vessel diameter changes, assuming the maximum and minimum diameters of the target blood vessel segment are D... max D min There must be an average blood vessel diameter. satisfy:

[0137] Since Murray's law is based on the assumption of minimum energy loss, if there is a stenotic region in the target blood vessel area, the blood flow within the stenotic region no longer strictly follows Murray's law due to viscosity loss and diffusion loss. Therefore, the blood flow at a target location in the blood vessel is calculated according to the principle of flow conservation, using the reference diameter within the stenotic region to match the blood flow at that target location. The first blood flow calculation formula is expressed as:

[0138] Where Q represents the target blood flow at the target location. The average blood flow is represented by D″, and the reference diameter of the blood vessel at the target location is represented by D″. The value is represented by the average diameter of the blood vessel, and b is the preset first coefficient, which can be 7 / 3.

[0139] If there is no stenosis in the target blood vessel region, the blood flow can be directly calculated from the actual blood vessel diameter at any location within the vessel. For the blood vessel diameter at a specific target location, the blood flow at that target location can be obtained based on the correspondence between blood flow and blood vessel diameter described by Murray's Law. The second blood flow calculation formula is expressed as:

[0140] Where Q represents the target blood flow at the target location. The average blood flow is represented by D, and D′ represents the diameter of the blood vessel at the target location. The value is represented by the average diameter of the blood vessel, and c is the preset second coefficient, which can be 7 / 3.

[0141] Figure 3 shows a functional block diagram of a blood flow calculation device 100 for arbitrary locations on a vascular tree according to an embodiment of the present invention. Depending on the functions implemented, the blood flow calculation device for arbitrary locations on a vascular tree may include a two-dimensional vascular skeleton line construction module 101, a three-dimensional vascular model reconstruction module 102, an average blood flow calculation module 103, a vascular stenosis region determination module 104, and a target blood flow calculation module 105. The modules described in this invention can also be referred to as units, which are a series of computer program segments that can be executed by the processor of the blood flow calculation device for arbitrary locations on a vascular tree and can perform fixed functions, and are stored in the memory of the blood flow calculation device for arbitrary locations on a vascular tree.

[0142] In this embodiment, the functions of each module / unit are as follows:

[0143] The two-dimensional vascular skeleton line construction module 101 is used to acquire angiography image sequences and extract the structure of the images in the angiography image sequences to obtain two-dimensional vascular skeleton lines.

[0144] The three-dimensional blood vessel model reconstruction module 102 is used to perform three-dimensional reconstruction based on the two-dimensional blood vessel skeleton lines to obtain a three-dimensional blood vessel model.

[0145] The average blood flow calculation module 103 is used to determine the corresponding target blood vessel region based on the three-dimensional blood vessel model, and to calculate the average blood flow corresponding to the target blood vessel region based on the number of transport frames corresponding to the angiography image sequence.

[0146] The vascular stenosis region determination module 104 is used to reconstruct the vascular reference diameter based on the vascular diameter corresponding to the target vascular region, and to determine the vascular stenosis region based on the vascular diameter and the vascular reference diameter.

[0147] The target blood flow calculation module 105 is used to calculate the target blood flow corresponding to the target location in the target blood vessel region based on the stenotic region of the blood vessel and the average blood flow.

[0148] In detail, each module in the blood flow calculation device 100 at any position of the vascular tree described in this embodiment of the invention uses the same technical means as the blood flow calculation method at any position of the vascular tree described in the accompanying drawings, and can produce the same technical effect, which will not be repeated here.

[0149] Figure 4 is a schematic diagram of the structure of an electronic device for calculating blood flow at any position in a vascular tree, according to an embodiment of the present invention.

[0150] The electronic device 200 may include a processor 201, a memory 202, a communication bus 203, and a communication interface 204. It may also include a computer program stored in the memory 202 and capable of running on the processor 201, such as a program for calculating blood flow at any location in a vascular tree.

[0151] In some embodiments, the processor 201 may be composed of integrated circuits, such as a single packaged integrated circuit or multiple integrated circuits with the same or different functions, including combinations of one or more central processing units (CPUs), microprocessors, digital processing chips, graphics processors, and various control chips.

[0152] The memory 202 includes at least one type of readable storage medium, including flash memory, portable hard drive, multimedia card, card-type memory (e.g., SD or DX memory), magnetic memory, disk, optical disk, etc.

[0153] The communication bus 203 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc.

[0154] The communication interface 204 is used for communication between the above-mentioned electronic device and other devices, including a network interface and a user interface.

[0155] It should be understood that the embodiments described are for illustrative purposes only and are not limited to this structure in the scope of the patent application.

[0156] The program for calculating blood flow at any location in the vascular tree stored in the memory 202 of the electronic device 200 is a combination of multiple instructions. When run in the processor 201, it can realize the method for calculating blood flow at any location in the vascular tree.

[0157] Specifically, the specific implementation method of the processor 201 of the above instructions can be referred to the description of the relevant steps in the corresponding embodiment of the accompanying drawings, which will not be repeated here.

[0158] Furthermore, if the modules / units integrated in the electronic device 200 are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. The computer-readable storage medium can be volatile or non-volatile. For example, the computer-readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, or a read-only memory (ROM).

[0159] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor of an electronic device, can implement a method for calculating blood flow at any location in the vascular tree.

[0160] In the several embodiments provided by this invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and other division methods may be used in actual implementation.

[0161] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for calculating blood flow at any location in a vascular tree, characterized in that, The method includes: A sequence of angiography images is acquired, and the structure of the images in the angiography image sequence is extracted to obtain a two-dimensional vascular skeleton line; A three-dimensional vascular model is obtained by performing three-dimensional reconstruction based on the two-dimensional vascular skeleton lines. The target vascular region is determined based on the three-dimensional vascular model, and the average blood flow corresponding to the target vascular region is calculated based on the number of transport frames corresponding to the angiography image sequence. The reference diameter of the blood vessel is reconstructed based on the blood vessel diameter corresponding to the target blood vessel region, and the narrowing region of the blood vessel is determined based on the blood vessel diameter and the reference diameter of the blood vessel. The target blood flow rate corresponding to the target location in the target blood vessel region is calculated based on the stenotic area of ​​the blood vessel and the average blood flow rate.

2. The method for calculating blood flow at any location in a vascular tree according to claim 1, characterized in that, The step of extracting the structure from the angiography image sequence to obtain a two-dimensional vascular skeleton line includes: Image segmentation is performed on the images in the angiography image sequence to obtain vascular images; The blood vessel image is binarized and thinned to obtain the two-dimensional blood vessel skeleton line.

3. The method for calculating blood flow at any location in a vascular tree according to claim 1, characterized in that, The step of performing three-dimensional reconstruction based on the two-dimensional vascular skeleton lines to obtain a three-dimensional vascular model includes: After aligning the angiography image sequence along the time axis, a binocular vision 3D reconstruction method is used to perform matrix mapping based on the two-dimensional vascular skeleton lines to obtain the correspondence between the two-dimensional vascular skeleton lines. Target pixels are selected one by one from the two-dimensional vascular skeleton line, and the vascular diameter corresponding to the target pixel is obtained from the images in the angiography image sequence based on the correspondence. Construct a corresponding closed contour line of the blood vessel based on the target pixel points and the blood vessel diameter; A three-dimensional blood vessel model is generated based on the closed contour line of the blood vessel corresponding to each pixel point on the two-dimensional blood vessel skeleton line.

4. The method for calculating blood flow at any location in a vascular tree according to claim 1, characterized in that, The step of calculating the average blood flow corresponding to the target blood vessel region based on the number of transport frames corresponding to the angiography image sequence includes: The transport time is calculated based on the number of transport frames corresponding to the angiography image sequence. The average blood flow velocity is calculated based on the transport time and the length of the target vascular region. Calculate the average cross-sectional area based on the blood vessel diameter corresponding to the target blood vessel region; The average blood flow rate is calculated based on the average blood flow velocity and the average cross-sectional area.

5. The method for calculating blood flow at any location in a vascular tree according to claim 4, characterized in that, The calculation of average blood flow velocity based on the transport time and the regional length of the target vascular region includes: Obtain proximal and distal landmarks in the target vascular region; The region length is obtained by calculating the shortest path based on the centerline between the near-end marker and the far-end marker. The ratio of the region length to the transport time is used as the average blood flow velocity.

6. The method for calculating blood flow at any location in a vascular tree according to claim 3, characterized in that, The step of determining the vascular stenosis region based on the vessel diameter and the vessel reference diameter includes: The stenosis point is determined based on the ratio of the vessel diameter to the reference vessel diameter; Based on the blood vessel diameter and the blood vessel reference diameter, respectively, fit the diameter function and the reference diameter function corresponding to the target blood vessel region; The vascular stenosis region is determined based on the intersection of the diameter function and the reference diameter function, as well as the stenosis point.

7. The method for calculating blood flow at any location in a vascular tree according to claim 3, characterized in that, The calculation of the target blood flow corresponding to the target location in the target blood vessel region based on the vascular stenosis region and the average blood flow includes: Calculate the average diameter of the blood vessels based on the diameter of the blood vessels in the target vascular region; Determine whether there is a stenotic area in the target blood vessel region: If so, the target blood flow is calculated using the first blood flow calculation formula based on the reference diameter of the blood vessel corresponding to the target location, the average diameter of the blood vessel, and the average blood flow. If not, the target blood flow is calculated using the second blood flow calculation formula based on the blood vessel diameter corresponding to the target location, the average blood vessel diameter, and the average blood flow.

8. The method for calculating blood flow at any location in a vascular tree according to claim 7, characterized in that, The first blood flow calculation formula is expressed as: Where Q represents the target blood flow at the target location. The average blood flow is represented by D″, and the reference diameter of the blood vessel at the target location is represented by D″. denoted as the average diameter of the blood vessel, and b as a preset first coefficient; The second blood flow calculation formula is expressed as follows: Where Q represents the target blood flow at the target location. The average blood flow is represented by D, and D′ represents the diameter of the blood vessel at the target location. The value is represented by the average diameter of the blood vessel, and c is the preset second coefficient.

9. The method for calculating blood flow at any location in a vascular tree according to claim 1, characterized in that, The number of transport frames corresponding to the angiography image sequence can be obtained through the following steps: The length of the blood vessel from the proximal and distal markers of the target blood vessel region to the entrance of the blood vessel tree is obtained in advance. Obtain the length of movement from the vascular tree entrance to the contrast agent movement position in the angiography image sequence; The number of transport frames is calculated by subtracting the distance between the travel length and the blood vessel length.

10. A device for calculating blood flow at any location in a vascular tree, characterized in that, The device includes: A two-dimensional vascular skeleton line construction module is used to acquire angiography image sequences and extract the structure of the images in the angiography image sequences to obtain two-dimensional vascular skeleton lines. The three-dimensional blood vessel model reconstruction module is used to perform three-dimensional reconstruction based on the two-dimensional blood vessel skeleton lines to obtain a three-dimensional blood vessel model. The average blood flow calculation module is used to determine the corresponding target blood vessel region based on the three-dimensional blood vessel model, and to calculate the average blood flow corresponding to the target blood vessel region based on the number of transport frames corresponding to the angiography image sequence. The vascular stenosis region determination module is used to reconstruct the vascular reference diameter based on the vascular diameter corresponding to the target vascular region, and to determine the vascular stenosis region based on the vascular diameter and the vascular reference diameter. The target blood flow calculation module is used to calculate the target blood flow corresponding to the target location in the target blood vessel region based on the stenotic region of the blood vessel and the average blood flow.

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