Method and system for quantitatively analyzing plugging effect of left auricle based on CT (Computed Tomography) image

Abstract

The invention discloses a method for quantitatively analyzing a left auricle occlusion effect based on a CT image. The method comprises the following steps: step 1, acquiring a heart CTA image; 2, performing three-dimensional reconstruction to obtain a heart three-dimensional image, and obtaining a left atrium three-dimensional image by using the left atrium segmentation model; 3, obtaining a left auricle occluder area by using the left auricle occluder segmentation model; 4, constructing a three-dimensional model of the left auricle occluder on the basis of the segmented left auricle occluder area so as to obtain a three-dimensional image of the left auricle occluder; 5, obtaining a three-dimensional plane of the left auricle plugging device, a front view of the plugging device and a left auricle opening plane; 6, left auricle occlusion postoperative evaluation parameters are extracted, wherein the parameters at least comprise the size, position and classification of residual shunt, the position of an occluder, the shoulder exposing position and height, the endothelialization degree of the occluder and the position of instrument-related thrombus; and 7, evaluating the left auricle occlusion effect according to the obtained evaluation parameters after the left auricle occlusion operation.

Description

Technical Field

[0001] The present invention relates to the field of image processing and machine learning, and in particular to a method and system for quantitatively analyzing left atrial appendage occlusion effects based on CT images. Background Art

[0002] Atrial fibrillation (AF) is the most common arrhythmia in the middle-aged and elderly. It can cause thrombosis in the left atrial appendage, and thromboembolic diseases such as ischemic stroke can occur after the thrombus falls off. Patients with AF often take anticoagulants to prevent thrombosis and stroke. However, anticoagulant therapy objectively has a certain risk of bleeding, and a considerable number of patients with AF have contraindications to oral anticoagulation. Left atrial appendage occlusion (LAAO) is an interventional procedure for the treatment of AF. It prevents thrombosis and detachment by implanting an occluder in the left atrial appendage, reducing the risk of embolic events in patients with AF. However, after implantation, the occluder needs to wait for the surface of the occluder to be completely endothelialized, which refers to the process of forming an endothelial cell layer on the surface of the occluder. The formation of this endothelial cell layer can reduce the direct contact between blood and the occluder material, thereby reducing the risk of thrombosis and other complications associated with the occluder. Therefore, accurately assessing the occurrence and severity of complications after left atrial appendage occlusion is crucial to guiding clinical decision-making and improving surgical strategies.

[0003] At present, the quantitative evaluation of complications after left atrial appendage closure, such as residual shunt, incomplete endothelialization of the occluder surface, occluder displacement, and occluder-related thrombosis, has become a research hotspot, and more and more researchers and doctors are committed to developing new methods and technologies to achieve accurate quantitative evaluation. However, the methods for evaluating complications after left atrial appendage closure in the prior art mainly rely on the doctor's experience and subjective judgment. This method has certain subjectivity and inconsistency, and has high requirements for the doctor's professional knowledge and experience. Therefore, how to quantitatively evaluate the effect of left atrial appendage surgery to improve the accuracy and repeatability of the evaluation is a problem that needs to be solved urgently.

[0004] In the field of image processing and computer vision, the inventors have explored methods for quantitatively evaluating endothelialization on the surface of occluders using CT images, such as the literature "A novel pragmatic paradigm to evaluate device endothelialization: lessons learned from a dual-watchman case". Some of these studies focus on texture analysis and feature extraction on the surface of occluders, such as evaluating the degree of endothelialization by calculating texture features on the surface of occluders, such as gray-level co-occurrence matrix, wavelet transform, etc. These methods can provide some quantitative indicators, but there are still certain subjectivity and limitations.

[0005] In recent years, the rapid development of medical image processing and machine learning technologies has provided new opportunities to solve this problem. Medical image processing technology can preprocess and enhance CT images to improve image quality and clarity. Feature extraction technology can extract target-related features from images, such as the shape, size and position of the atrium, and the surface structure of the device. Machine learning technology can use these features to train models and realize automatic recognition and analysis of complications after left atrial appendage surgery. Summary of the invention

[0006] The present invention provides a method for quantitatively analyzing the effect of left atrial appendage occlusion based on CT images, so as to obtain relevant surface parameters of the occluder efficiently, quickly and accurately, and provide a basis for automatic identification and analysis of complications after left atrial appendage surgery.

[0007] To this end, the present invention provides the following technical solutions:

[0008] A method for quantitatively analyzing left atrial appendage occlusion effect based on CT images, the method comprising:

[0009] Step 1: Acquire CTA images of the patient's heart after left atrial appendage occlusion surgery;

[0010] Step 2: performing three-dimensional reconstruction on the cardiac CTA image sequence to obtain a three-dimensional image of the heart, and obtaining a three-dimensional image of the left atrium using a left atrium segmentation model;

[0011] Step 3: Segment the left atrial appendage occluder area in the CTA image using the left atrial appendage occluder segmentation model;

[0012] Step 4: constructing a three-dimensional model of the left atrial appendage occluder based on the segmented left atrial appendage occluder region, and obtaining a three-dimensional image of the left atrial appendage occluder through three-dimensional reconstruction;

[0013] Step 5: Based on the three-dimensional image of the left atrial appendage occluder, a three-dimensional plane of the left atrial appendage occluder, a front view of the occluder, and a plane of the left atrial appendage opening are obtained;

[0014] Step 6: extracting evaluation parameters after left atrial appendage occlusion surgery, the parameters at least including: the size, location and grade of residual shunt, the location, shoulder position and height of the occluder, the degree of endothelialization of the occluder, and the location of device-related thrombus;

[0015] Step 7: Evaluate the left atrial appendage occlusion effect based on the obtained evaluation parameters after left atrial appendage occlusion surgery.

[0016] Furthermore, the steps of step 3 for constructing the left atrial appendage occluder segmentation model are:

[0017] Step 3.1: Collect CTA images of patients after left atrial appendage occlusion surgery, segment the left atrial appendage occluder, and obtain a training data set and a corresponding mask;

[0018] Step 3.2: Based on the training data set and mask obtained in step 3.1, a U-net algorithm model is trained, and the trained model is used as a left atrial appendage occluder segmentation model.

[0019] Furthermore, the specific steps of step 5 include:

[0020] Step 5.1: Based on the center point of the occluder rivet in the left atrial appendage occluder image as the starting point P1, the tip of the occluder as the end point P2, the path direction is P1→P2, and the connecting line from P1 to P2 is used as the initial axis of the occluder, and the axis of the occluder is continuously corrected through iterative calculation to finally obtain the actual axis of the occluder;

[0021] Step 5.2: The tangent line passing through the center point of the occluder rivet and perpendicular to the initial axis is used as the tangent line of the left atrial surface of the occluder. The tangent line of the left atrial surface of the occluder is corrected while the axial direction of the occluder is iteratively calculated, and finally the actual tangent line of the left atrial surface of the occluder is obtained;

[0022] Step 5.3: Fix the obtained tangent of the left atrial surface of the actual occluder and the actual axial direction of the occluder to 90°, thereby obtaining the three-dimensional planes of the left atrial appendage occluder: axial section, sagittal plane, and coronal plane;

[0023] Step 5.4: The obtained axial section, coronal plane, and sagittal plane are fixed at 90° angles in pairs, and the window width and window position of the axial section are adjusted until the CT image layer of the occluder can be displayed, thereby obtaining a front view of the left atrial appendage occluder;

[0024] Step 5.5: In the 3D reconstruction multiplane, use the orthogonal plane method to place the crosshairs at the level of the proximal circumflex artery;

[0025] Step 5.6: Rotate the crosshairs of the coronal and sagittal planes in turn, adjust the positions of the crosshairs of the coronal and sagittal planes, and place the crosshairs of the coronal and sagittal planes at the circumflex branch and the pulmonary vein crest, respectively, so as to determine the position of the left atrial appendage opening, and use the plane corresponding to the crosshairs placed at the circumflex branch and the pulmonary vein crest as the left atrial appendage opening plane.

[0026] Furthermore, step 6 includes the following specific steps:

[0027] Step 6.1: Determine the location, size, and grade of residual shunts;

[0028] Step 6.2: Determine the position of the occluder, including the height and position of the shoulder;

[0029] Step 6.3: Determine the contrast attenuation thickness (HAT) and endothelialization degree of the occluder;

[0030] Step 6.4: Evaluate the HAT. If the HAT thickness is greater than 3 mm, observe whether the HAT is regular. If not, consider it as DRT and indicate the current DRT position by the clock method.

[0031] Furthermore, the specific steps of step 6.1 are:

[0032] Step 6.1.1: Rotate the crosshairs in the coronal and sagittal planes respectively, and define the path of contrast medium from the left atrium to the left atrial appendage as the residual shunt in the sagittal or coronal plane;

[0033] Step 6.1.2: Determine the control line at the residual shunt based on the axial section and obtain the cross section of the residual shunt;

[0034] Step 6.1.3: Determine the minimum diameter and area of ​​the residual shunt based on the cross section;

[0035] Step 6.1.4: Classify the residual shunt according to its minimum diameter: if the diameter is 0-1mm, it is a trace amount; if the diameter is 1mm-3mm, it is a small amount; if the diameter is 3mm-5mm, it is a medium amount; if it is greater than 5mm, it is a large amount.

[0036] Furthermore, the specific steps of step 6.2 are:

[0037] Step 6.2.1: Rotate the crosshairs of the axial section until the occluder shoulder is located in the sagittal or coronal plane;

[0038] Step 6.2.2: Take the left atrial appendage opening plane as the starting point and the highest position of the occluder shoulder as the end point, calculate the Euclidean distance between the two points, and use the distance as the height of the occluder shoulder.

[0039] Furthermore, the specific steps of step 6.3 are:

[0040] Step 6.3.1: Detect the intersection areas of all the cross beams of the left atrial appendage occluder on the three-dimensional image, and select the intersection area with the largest volume as the center point of the occluder;

[0041] Step 6.3.2: Start searching from the position close to the center point of each beam. When the angle between the vector A formed by the current search point to the next search point and the vector B formed by the previous search point to the current search point is the largest, the current search point is taken as the inflection point of the beam.

[0042] Step 6.3.3: Calculate the planes that can be formed by the inflection points of the beams determined in step 5.3.2, select the plane with the largest number of inflection points, and use the normal vector of the plane as the vector from the center point to the end of the occluder; if the number of inflection points belonging to each plane in the planes that can be formed by the inflection points of the beams is the same, select the plane closest to the center point of the occluder, and use the normal vector of the plane as the vector from the center point to the end of the occluder;

[0043] Step 6.3.4: Using the vector from the center point to the end of the occluder determined in step 5.3.3 as the normal vector of the plane, calculate the area of ​​the quasi-circular shape enclosed by the crossbeam of the occluder on each plane, and take the plane with the largest area as the maximum cross-section of the occluder;

[0044] Step 6.3.5: Segment the endothelialized area on the surface of the left atrial appendage occluder using an endothelialized area segmentation method;

[0045] Step 6.3.6: plotting the endothelial thickness at each pixel in the endothelialized area using different colors;

[0046] Step 6.3.7: Calculate the endothelialization ratio by the following formula and use the endothelialization ratio as the degree of endothelialization after left atrial appendage occlusion:

[0047] Endothelialization ratio = endothelialization coverage area of ​​the left atrial surface of the occluder / area of ​​the left atrial surface of the occluder*100%.

[0048] Furthermore, the endothelialization area segmentation method in step 6.3.5 is a grayscale threshold segmentation algorithm, and its specific steps are:

[0049] Step 6.3.5.1: along the two normal vectors of the maximum cross section of the occluder determined in step 6.3.4, starting from the maximum cross section of the occluder, search for pixel points that meet the endothelialization CT value range within the maximum cross section range in each layer of the image;

[0050] Step 6.3.5.2: When the pixel points belonging to the left atrium area are searched, the search is stopped, and the searched pixel points are used as the pixel points of the endothelialization area, and the area formed by combining these pixel points is used as the endothelialization area.

[0051] Furthermore, the endothelialization area segmentation method in step 6.3.5 is a U-net segmentation algorithm, and its specific steps are:

[0052] Step 1: Based on the CT image data with pre-annotated endothelialization areas and reviewed by doctors in the field of cardiology, the endothelialization area segmentation model is trained using the U-net algorithm;

[0053] Step 2: Obtain the CT image of the current patient, and use the trained endothelialization region segmentation model to segment the endothelialization region in the image.

[0054] A system for extracting left atrial appendage data parameters based on CT images is implemented based on the above method, and the system includes:

[0055] An image sequence acquisition module is used to acquire CTA images of the heart of a patient after left atrial appendage occlusion surgery;

[0056] An image reconstruction module performs three-dimensional reconstruction on the cardiac CTA image sequence to obtain a three-dimensional cardiac image;

[0057] Segmentation module, including,

[0058] A left atrium segmentation unit, used for segmenting a three-dimensional image of the left atrium using a left atrium segmentation model;

[0059] A left atrial appendage occluder segmentation unit, used for segmenting the left atrial appendage occluder region in the CTA image using the left atrial appendage occluder segmentation model;

[0060] A three-dimensional reconstruction module is used to construct a three-dimensional model of the left atrial appendage occluder based on the segmented left atrial appendage occluder area, and obtain a three-dimensional image of the left atrial appendage occluder through three-dimensional reconstruction;

[0061] A three-dimensional plane acquisition module is used to acquire the three-dimensional plane of the left atrial appendage occluder, the front view of the occluder and the left atrial appendage opening plane based on the three-dimensional image of the left atrial appendage occluder;

[0062] The occluder parameter extraction module is used to extract the evaluation parameters after left atrial appendage occlusion surgery, and the parameters include at least: the size, location and grade of residual shunt, the location, shoulder position and height of the occluder, the degree of endothelialization of the occluder, and the location of device-related thrombus;

[0063] The evaluation module is used to evaluate the left atrial appendage occlusion effect based on the evaluation parameters obtained after the left atrial appendage occlusion operation.

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] First, the present invention intelligently extracts left atrium and left atrial appendage occluder images based on CT images, and quantitatively analyzes the postoperative effect of left atrial appendage occlusion, so as to improve the accuracy and repeatability of the postoperative effect evaluation of left atrial appendage occlusion, and provide a basis for the postoperative anticoagulation scheme;

[0066] Second, the present invention proposes the POET evaluation principle, which can enable clinicians to quickly and accurately evaluate the postoperative effects of left atrial appendage occlusion on patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1a-1b is a diagram showing the location of the residual shunt; Figure 1a Standard left superior pulmonary vein and mitral valve, aorta; Figure 1b The middle PDL position is 8:00-9:00;

[0068] Figure 2 This is a diagram to evaluate the degree of endothelialization completion;

[0069] Figure 3a-Figure 3b is a location map of device-related thrombus; Figure 3b The DRT position is 1:00-3:00

[0070] Figure 4a-4d They are the three-dimensional reconstruction of the left atrium and occluder, the axial section of the left atrial appendage occluder, the sagittal plane of the left atrial appendage occluder, and the coronal plane of the left atrial appendage occluder;

[0071] Figure 5a-5d They are the three-dimensional reconstruction of the left atrium and occluder, the front view of the left atrial appendage occluder, the sagittal plane of the left atrial appendage occluder, and the coronal plane of the left atrial appendage occluder;

[0072] Figure 6 It is the measurement diagram of the occluder with exposed shoulder;

[0073] Figure 7a-7d is a schematic diagram of DRT; Figure 7a-Figure 7b The base is irregular. Figure 7c-7d For the base rule;

[0074] Figure 8 is a schematic diagram of the ray casting algorithm;

[0075] Fig. 9 Build results for the three-dimensional image of the left atrial appendage occluder;

[0076] Fig.10 It is a schematic diagram of the center point and the beam point; Fig.11 The results are shown in Figure 5. The results are based on staining according to endothelial thickness. DETAILED DESCRIPTION

[0077] The present invention applies CT images to the evaluation of complications after left atrial appendage surgery, and provides a method for quantitatively analyzing complications after left atrial appendage occlusion surgery based on CT images. A three-dimensional image of the heart is obtained by three-dimensionally reconstructing a coronary CTA image sequence, and then a three-dimensional image of the left atrium and a left atrial appendage occluder is obtained by using the three-dimensional image of the heart and a pre-established left atrial segmentation model; then, relevant parameters after left atrial appendage occlusion surgery are extracted from the three-dimensional image, and the relevant parameters include the size, position and grade of residual shunt, the position of the occluder, the shoulder position and the adjacent relationship with the surrounding structure, the endothelialization degree of the occluder, and the position, size and grade of the device-related thrombus. The obtained parameters can be used to quickly evaluate the left atrial appendage occlusion effect of the patient.

[0078] 1. Left atrium and left atrial appendage occluder segmentation model

[0079] The present invention adopts the left atrium segmentation model disclosed in the inventor's previous Chinese patent number "CN112244883A" "Method and system for extracting left atrial appendage data parameters based on CT images", which is used to extract the left atrium three-dimensional image from the three-dimensional coronary artery image. The establishment and training process of the model has been disclosed in the document and will not be repeated in the present invention.

[0080] In addition, the present invention also constructs a left atrial appendage occluder segmentation model for extracting a three-dimensional image of the left atrial appendage occluder from a three-dimensional coronary artery image; the steps of constructing the model are: (1) collecting CTA images of patients after left atrial appendage occlusion surgery, manually performing left atrial appendage occluder segmentation, and obtaining a training data set and a corresponding mask required for training a U-net algorithm model; (2) based on the obtained training data set and the corresponding mask, using the U-net algorithm framework, training a left atrial appendage occluder segmentation model.

[0081] Using the trained left atrium segmentation model and left atrial appendage occluder segmentation model, the left atrium 3D image and the left atrial appendage occluder 3D image can be extracted from the 3D coronary artery image. The specific steps of constructing the left atrial appendage occluder 3D image using the left atrial appendage occluder segmentation model are as follows:

[0082] (1) Based on the CTA images of patients after left atrial appendage occlusion surgery, the left atrial appendage occluder region in the CTA images is segmented using the left atrial appendage occluder segmentation model established above;

[0083] (2) Based on the segmented LAA occluder region, the SSD algorithm was used to construct a three-dimensional model of the occluder;

[0084] (3) Using computer graphics algorithms to construct a three-dimensional image of the left atrial appendage occluder, such as Fig. 9 As shown, the blue area in the figure is the constructed three-dimensional model of the occluder.

[0085] 2. POET Principle

[0086] The present invention proposes a new POET principle for evaluating the effect of left atrial appendage occlusion based on the LAAO principle: P, i.e., residual shunt (Peri-divice leak, PDL), including the size, position and grading of PDL; O, i.e., position (pOsition), including the shoulder position (placement depth) and shoulder height of the occlusion; E, i.e., endothelialization, including the degree of endothelialization; T, i.e., device-related thrombosis (DRT), including the size of DRT, the base size and the grading of contrast agent attenuation thickness (HAT).

[0087] 3. The method of the present invention

[0088] Based on the above-mentioned left atrial segmentation model and POET principle, the present invention proposes a method for quantitatively analyzing the effect of left atrial appendage occlusion based on CT images, comprising the following steps:

[0089] Step 1: Acquire coronary CTA image sequence;

[0090] Step 2: Perform three-dimensional reconstruction of the coronary CTA image sequence to obtain a three-dimensional image of the left atrium and adjacent structures;

[0091] Step 3: inputting the three-dimensional image into the pre-trained left atrium segmentation model and left atrial appendage occluder segmentation model to obtain the left atrium three-dimensional image and the left atrial appendage occluder three-dimensional image model;

[0092] Through three-dimensional reconstruction, the axial section, coronary plane, and sagittal plane of the left atrial appendage occluder are obtained, and then the front view of the left atrial appendage occluder and the left atrial appendage opening plane are obtained using the orthogonal method;

[0093] The present invention specifically adopts the following three-dimensional reconstruction method:

[0094] Three-dimensional reconstruction is volume reconstruction. Volume reconstruction directly studies the changes of light when it passes through the three-dimensional volume data field to obtain the final rendering result, so volume reconstruction is also called direct volume rendering. Volume rendering methods are mainly divided into two categories: image space-ordered volume rendering methods and object space-ordered volume rendering methods: (1) The image space-ordered volume rendering method starts from each pixel on the screen and emits a ray according to the viewpoint direction. This ray passes through the three-dimensional data field and performs equidistant sampling along the ray to calculate the opacity and color value of the object at the sampling point. The color and opacity of the sampling points on a ray can be synthesized in two orders, from front to back or from back to front (MaxIP or MinIP takes the maximum or minimum value on the ray), thereby calculating the color value of the pixel on the screen. This method simulates the process of light passing through an object from the reverse direction. (2) The volume rendering method based on the object space order first calculates the color and opacity of each data point based on the function value of the point, then projects each data point onto the image plane based on the given viewing plane and viewing direction, and synthesizes and calculates the opacity and color according to the occlusion order of the data points in space to finally obtain the image.

[0095] 1) Ray casting

[0096] The ray casting method projects light from each pixel on the image plane to the data field, samples the light or integrates along the line segment to calculate the brightness and opacity, and synthesizes the image in the sampling order to obtain the result image. The ray casting method is a method that takes the image space as the order. It simulates the whole process of light passing through the object from the reverse direction, and finally calculates the color of the light after it reaches the data field.

[0097] like Figure 8 As shown, the ray casting algorithm mainly has the following process (see the drawing process above):

[0098] ① Data preprocessing: including adjustment of sampling grid, data contrast enhancement, etc.;

[0099] ②Data classification and lighting effect calculation: Establish the mapping between field value to color value and opacity respectively, and use the central difference method to calculate the normal vector and calculate the lighting effect;

[0100] ③ Ray casting: From each pixel on the screen, cast light along the viewing direction, pass through the data field, sample each ray, and interpolate to calculate the color value and opacity;

[0101] ④ Synthesis and drawing: On each ray, the color value of each sampling point is synthesized in the order of front and back to get the color value of the pixel and display the pixel. If it is the maximum density projection (MaxIP) or minimum density projection (MinIP) mode, the maximum or minimum value of all sampling points on this ray is directly taken as the final pixel color value.

[0102] 2) Projection method

[0103] The starting point of the projection volume rendering method is to use the correlation between the area and the volume in the field. It projects the voxels onto the image plane, calculates the contribution of each voxel to the pixel, and synthesizes the effect of each voxel according to the order of the front and back occlusion of the voxel. This method essentially calculates the impact of the light emitted by each voxel in the data field on each pixel on the image when it reaches the image plane, and finally calculates the image. The main steps of projection volume rendering are as follows:

[0104] ① Voxel traversal: determine the front and back occlusion order of voxels in the data field, and traverse the voxels from front to back or from back to front;

[0105] ② Voxel decomposition: Each voxel is decomposed into a group of sub-voxels, and the projection contours of the sub-voxels must not overlap on the observation plane;

[0106] ③ Projection and synthesis: The sub-voxel is projected onto the image plane to obtain a projection polygon; the values ​​of the vertices of the projection polygon are calculated, and the brightness contribution of the projection polygon to the covered pixel is calculated by scan conversion, and synthesized with the original pixel value;

[0107] Step 4: extracting left atrial appendage occluder related parameters from the left atrial appendage occluder three-dimensional image, the front view of the occluder and the left atrial appendage opening plane, wherein the left atrial appendage occluder related parameters at least include: the size, position and grade of residual shunt, the position, shoulder position and height of the occluder, the degree of endothelialization of the occluder, and the position, size and grade of device-related thrombus;

[0108] Step 5: The clinician performs a postoperative evaluation of the left atrial appendage occlusion using the left atrial appendage occluder related parameters obtained from step 4.

[0109] During left atrial appendage occlusion surgery, the effect of the occluder needs to be evaluated after surgery. The correct extraction of left atrial appendage occluder related parameters can provide reference for subsequent clinical evaluation and scientific research analysis.

[0110] Furthermore, the specific steps of obtaining the left atrial appendage occluder three-dimensional plane, the occluder front view and the left atrial appendage opening plane include:

[0111] Step 3.1: Obtain the three-dimensional plane of the left atrial appendage occluder; specifically including:

[0112] (1) Obtain the anatomical image of the left atrial appendage occluder using the left atrial appendage segmentation model, such as Figure 4a As shown, the axial direction of the occluder is the direction of the umbrella handle, and the occluder is riveted to the umbrella tip;

[0113] (2) Based on the anatomical image, the center point of the occluder in the left atrial appendage occluder image ( Figure 5b The red dot in the figure is taken as the starting point P1, the tip of the occluder is taken as the end point P2, the path direction is P1→P2, and the connecting line from P1 to P2 is taken as the initial axial direction of the occluder ( Figure 5c and Figure 5d The axial direction of the occluder is continuously corrected through iterative calculation, and finally the actual axial direction of the occluder is obtained; at the same time, after the initial axial direction of the occluder is obtained, the tangent passing through the center point of the occluder rivet and perpendicular to the initial axial direction is used as the tangent of the left atrial surface of the occluder. As the axial direction of the occluder is iteratively calculated, the tangent of the left atrial surface of the occluder is corrected at the same time, and finally the actual tangent of the left atrial surface of the occluder is obtained;

[0114] (3) The tangent line of the actual left atrial surface of the occluder and the actual axial direction of the occluder are fixed at 90°, thereby obtaining the three-dimensional plane of the left atrial appendage occluder (step), as shown in FIG. Figure 4b-4d As shown, Figure 4c and Figure 4d The yellow line (indicated by the yellow arrow) represents the axial section reference line. Figure 4b and Figure 4c The blue line in the figure (indicated by the blue arrow) represents the coronal reference line. Figure 4b and Figure 4d The green line in the figure (indicated by the green arrow) represents the sagittal reference line.

[0115] (4) Taking the left atrial appendage occluder rivet as the starting point, taking a plane perpendicular to the left atrial surface of the occluder at preset intervals along the starting point to obtain multiple sections. Then, the left atrial appendage occluder contour and the centroid of the occluder of each section are determined in turn, and the centroids on adjacent sections are connected to obtain the CT values ​​of N left atrial appendage occluders, and a grayscale histogram inside the organ is generated according to the CT values; then, a grayscale distribution Gaussian probability curve is calculated by the grayscale histogram, and the contour of the left atrial appendage occluder on each section is determined using the obtained grayscale distribution Gaussian probability curve.

[0116] Step 3.2: Obtain a front view of the left atrial appendage occluder;

[0117] Specifically, the axial section, coronal plane, and sagittal plane obtained in step 3.1 are fixed at 90° angles in pairs, and the window width and window position of the axial section are adjusted until the CT image layer of the occluder can be displayed, thereby obtaining a front view of the left atrial appendage occluder;

[0118] Through three-dimensional reconstruction, a VR image of the left atrial appendage occluder can also be obtained. The VR image can intuitively show the relationship between the occluder and the surrounding adjacent structures, and can be used to obtain parameters such as PDL, DRT, and the position, size, and height of the occluder shoulder.

[0119] Step 3.3: Obtain the left atrial appendage opening plane;

[0120] Specifically, (1) in the three-dimensional reconstruction of multiple planes, use the orthogonal plane method to place the crosshairs at the level of the proximal end of the circumflex branch; (2) rotate the crosshairs of the coronal and sagittal planes in turn, adjust the positions of the crosshairs of the coronal and sagittal planes, and place the crosshairs of the coronal and sagittal planes at the circumflex branch and the pulmonary vein crest, respectively, to determine the position of the left atrial appendage opening, and the corresponding axial section can show the left atrial appendage opening. At this time, the plane corresponding to the crosshairs placed at the circumflex branch and the pulmonary vein crest is the left atrial appendage opening plane, as shown in FIG. Figure 6 shown.

[0121] Furthermore, the step 4 of extracting the surface parameters of the occluder includes:

[0122] Step 4.1: Determine the location, size, and grade of the residual shunt (PDL);

[0123] Specifically, (1) the crosshairs of the coronal plane and the sagittal plane are rotated respectively, and the channel of the contrast agent from the left atrium to the left atrial appendage in the sagittal plane or the coronal plane is regarded as the residual shunt; (2) the control line of the residual shunt is determined based on the axial section to obtain the cross section of the residual shunt; (3) the minimum diameter and area of ​​the residual shunt are determined based on the cross section;

[0124] When determining the diameter, multiple starting points and end points are determined on the cross section of the residual shunt, and the distance between the two points is obtained by calculating the Euclidean distance between the two points, which is used as the diameter of the residual shunt. The minimum diameter and maximum diameter of the residual shunt are obtained by comparison.

[0125] When determining the area, the ROI region was first determined on the axial section of the residual shunt using the ROI regional grid method, and then the area of ​​the ROI region was calculated using the pixel counting method;

[0126] After determining the minimum diameter and area of ​​the residual shunt, the minimum diameter of the residual shunt (PDL) is used for grading according to existing clinical standards. Generally, it is graded according to three cutoff points: 1mm, 3mm, and 5mm. Specifically, 0-1: trace; 1-3: small amount; 3-5: moderate amount; >5: large amount.

[0127] Next, in the three-dimensional reconstructed multi-plane, the axial section of the occluder is displayed in 3D, and the coronal and sagittal crosshairs are adjusted respectively. The axial section plane is adjusted to the mitral valve ring below, the left upper pulmonary vein below, and the aorta in front. The occluder rivets are used as clock points, with the left upper pulmonary vein direction at 12 o'clock, the mitral valve ring direction at 6 o'clock, the aorta direction at 3 o'clock, and the posterior side at 9 o'clock, so that the position of the residual shunt is represented by "nn" points.

[0128] Among them, the "nn" point is a clock notation. Since PDL refers to the residual channel between the left atrium and the left atrial appendage, it is a three-dimensional structure, so its cross section (i.e., the image displayed on the axial section) is a range. For example, the range of residual shunt can be 7 o'clock to 9 o'clock, such as Figure 1b As shown in the figure, the white dotted line is the PDL, the yellow line is the position of 8 o'clock, and the remaining blue lines are the positions of 9 o'clock, 6 o'clock, 3 o'clock, and 12 o'clock respectively;

[0129] Step 4.2: Extract the occluder position (pOsition), including the shoulder-exposed height and shoulder-exposed position;

[0130] Specifically, (1) in the three-dimensional reconstruction multi-plane, the crosshairs of the axial section are rotated until the position of the occluder shoulder is determined in the sagittal plane or the coronal plane; (2) the left atrial appendage opening plane obtained in step 3.3 is used as the starting point, and the highest position of the occluder shoulder is used as the end point, and the Euclidean distance between the two is calculated, and the distance is used as the height of the occluder shoulder, such as Figure 6 As shown in the figure, the red line is the left atrial appendage opening plane, the blue line is the position of the occluder shoulder, and the distance between the two lines is the height of the occluder shoulder;

[0131] In the three-dimensional reconstruction of multiple planes, the axial section of the occluder is displayed in 3D, and the coronal and sagittal crosshairs are adjusted respectively. The axial section plane is adjusted to the mitral valve ring below, the left upper pulmonary vein below, and the aorta in front. The occluder rivets are used as clock points, with the left upper pulmonary vein direction at 12 o'clock, the mitral valve ring direction at 6 o'clock, the aorta direction at 3 o'clock, and the back side at 9 o'clock. The position where the occluder is exposed is indicated by the "nn" point.

[0132] Step 4.3: Extract the endothelialization ratio of the occluder;

[0133] (1) Based on the three-dimensional image of the left atrial appendage occluder, the center point of the occluder is determined on the three-dimensional image of the left atrial appendage occluder, and a vector is drawn between the center point of the occluder and the end of the occluder;

[0134] The specific steps include:

[0135] ① Determine the center point of the occluder: Detect the intersection area of ​​all the occluder beams on the three-dimensional image of the left atrial appendage occluder, and select the intersection area with the largest volume as the center point of the occluder; in case the intersection area is difficult to detect or inaccurate due to compression and deformation of the occluder after implantation in the body, the doctor will manually determine it;

[0136] ② Determine the inflection point of each occluder beam, start searching from the position close to the center point of each beam, and when the angle between the vector A formed by the current search point to the next search point and the vector B formed by the previous search point to the current search point is the largest, take the current search point as the inflection point of the beam, such as Fig.10 As shown, the red point in the figure is the center point of the occluder, and the blue point is the inflection point of the beam;

[0137] ③ Calculate the planes that can be formed by the inflection points of the beams determined in the previous step, select the plane with the most inflection points, and use the normal vector of the plane as the vector from the center point to the end of the occluder; if the number of inflection points belonging to each plane in the planes that can be formed by the inflection points of each beam is the same, select the plane closest to the center point of the occluder, and use the normal vector of the plane as the vector from the center point to the end of the occluder;

[0138] Likewise, the vector from the center point to the end of the occluder can also be determined manually.

[0139] (2) Determine the maximum cross-section of the occluder

[0140] Taking the vector from the center point to the end of the occluder as the normal vector of the plane, calculate the area of ​​the quasi-circular shape enclosed by the cross beam of the occluder on each plane, and take the plane with the largest area as the maximum cross section of the occluder. At this time, the normal vector of the maximum cross section of the occluder is also the vector from the center point to the end of the occluder;

[0141] (3) Segmentation of the endothelialized area on the surface of the left atrial appendage occluder

[0142] Specific segmentation methods include gray threshold segmentation and U-net algorithm segmentation;

[0143] ① Grayscale threshold segmentation

[0144] Step 1: Along the two normal vectors of the maximum cross section of the occluder, starting from the maximum cross section of the occluder, search for pixel points that meet the range of endothelialization CT value (pixel value) within the maximum cross section range of each layer of the image. The range of endothelialization CT value is generally determined by doctors in the field of professional cardiology. In clinical practice, the CT value of normal myocardium is less than 100HU, or the CT value of HAT / the CT value range of left atrium: 0.10-0.82;

[0145] Step 2: When the pixel points belonging to the left atrium area are searched, the search is stopped, and the searched pixel points are used as the pixel points of the endothelialization area, and the area formed by combining these pixel points is used as the endothelialization area.

[0146] ②U-net algorithm to segment endothelialization area

[0147] Step 1: Based on CCTA image data with pre-annotated endothelialization areas and reviewed by doctors in the field of cardiology, the endothelialization area segmentation model is trained using the U-net algorithm;

[0148] Step 2: Obtain the CCTA image of the current patient and use the trained endothelial region segmentation model to segment the endothelial region in the image.

[0149] (4) Calculation of endothelial thickness

[0150] On the maximum cross-section of the occluder, the endothelial thickness at each pixel is plotted with different colors. For example, purple is used when the HAT thickness is 0 ≤ HAT < 1 mm, and blue is used when the HAT thickness is 1 ≤ HAT < 2 mm. Fig.11 As shown;

[0151] (5) Calculation of the degree of endothelialization

[0152] The ratio of complete endothelialization (En Ratio) was calculated by the following formula and used as the degree of complete endothelialization after left atrial appendage occlusion:

[0153] Endothelialization ratio = endothelialization coverage area of ​​the left atrial surface of the occluder / area of ​​the left atrial surface of the occluder*100%;

[0154] The main steps for calculating the endothelialization ratio are shown in Table 1.

[0155] Table 1

[0156]

[0157] Step 4.4: Extract the location and size of device-related thrombus;

[0158] Specifically, the thickness of the HAT calculated in step 4.3 is judged. If the HAT thickness is greater than 3 mm, observe whether the base of the HAT is regular. If not (i.e., the diameter is inconsistent when starting from the occluder surface and / or continuing with the left atrium), it is regarded as DRT (device-related thrombosis). Figure 7a-7d As shown, Figure 7a , Figure 7b For irregular, Figure 7c , Figure 7dFor the specific judgment method, please refer to the literature "Cardiac Computed Tomography Following Watchman FLXImplantation" and the literature "Detection of Device-Related Thrombosis Following Left Atrial Appendage Occlusion".

[0159] In the three-dimensional reconstruction of multiple planes, the axial section of the occluder is displayed in 3D, and the coronal and sagittal crosshairs are adjusted respectively. The axial section plane is adjusted to the mitral valve ring below, the left upper pulmonary vein below, and the aorta in front. The occluder rivets are used as clock points, with the left upper pulmonary vein direction at 12 o'clock, the mitral valve ring direction at 6 o'clock, the aorta direction at 3 o'clock, and the posterior side at 9 o'clock. The position of the device-related thrombus is represented by "nn" points.

[0160] Accordingly, an embodiment of the present invention also provides a system for quantitatively analyzing complications after left atrial appendage occlusion surgery based on CT images.

[0161] In this embodiment, the system includes the following modules:

[0162] An image sequence acquisition module, used for acquiring a coronary CTA image sequence;

[0163] An image reconstruction module, used for performing three-dimensional reconstruction on the coronary CTA image sequence to obtain a three-dimensional coronary image;

[0164] A segmentation module, used to obtain a three-dimensional image of the left atrium and the left atrial appendage occluder by using the three-dimensional coronary artery image and a pre-established left atrium segmentation model;

[0165] An occluder parameter extraction module is used to extract occluder surface parameters from the three-dimensional image of the left atrial appendage occluder, wherein the parameters include at least: the size, position and grade of residual shunt, the position, shoulder position and shoulder height of the occluder, the degree of endothelialization of the occluder, and the location and size of device-related thrombus;

[0166] The evaluation module is used to evaluate the left atrial appendage occlusion effect based on the obtained relevant parameters after the left atrial appendage occlusion operation.

[0167] Example

[0168] Patient A, who had a history of atrial fibrillation and stroke, underwent percutaneous left atrial appendage occlusion and underwent coronary CTA examination 3 months after the operation. We can obtain the original images of the patient's coronary CTA or left atrial CTA through the PACS system, determine the axial direction of the occluder and the left atrial appendage opening plane, and perform three-dimensional reconstruction and segmentation of the left atrium and left atrial appendage occluder. According to the POET principle, when obtaining the residual shunt parameters, in the three-dimensional reconstructed image, rotate the sagittal or coronal plane to find the residual channel between the left atrium and the left atrial appendage, place the axial section baseline at the residual shunt, and measure the size of the residual shunt in the axial section. Use VR mode to display the heart structure, adjust the image so that the mitral valve ring is below, the aorta is in front, and the left superior pulmonary vein is above. The position of the residual shunt is expressed using the clock method and expressed as Figure 1a-1b . In the three-dimensional reconstruction multi-plane, the crosshairs of the rotating axial section are used to find the position of the exposed shoulder of the occluder. The left atrial appendage opening plane is used as the starting point, and the highest position of the exposed shoulder of the occluder is used as the end point. The Euclidean distance between the two is calculated and used as the height of the exposed shoulder of the occluder. The endothelialization quantitative analysis function is used to draw the HAT area on the surface of the occluder, and the endothelialization calculation formula is used to calculate the endothelialization ratio. Finally, if the patient has no DRT and the endothelialization ratio is ≥90%, it is determined that the patient has a good postoperative effect.

[0169] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatus.

[0170] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0171] The embodiments of the present invention are described in detail above. The present invention is described in detail using specific implementation methods herein. The description of the above embodiments is only used to help understand the method and system of the present invention. It is only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should belong to the scope of protection of the present invention, and the content of this specification should not be understood as limiting the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for quantitatively analyzing left atrial appendage occlusion effect based on CT images, characterized in that: The method comprises: Step 1: Acquire CTA images of the patient's heart after left atrial appendage occlusion surgery; Step 2: performing three-dimensional reconstruction on the cardiac CTA image sequence to obtain a three-dimensional image of the heart, and obtaining a three-dimensional image of the left atrium using a left atrium segmentation model; Step 3: Segment the left atrial appendage occluder area in the CTA image using the left atrial appendage occluder segmentation model; Step 4: constructing a three-dimensional model of the left atrial appendage occluder based on the segmented left atrial appendage occluder region, and obtaining a three-dimensional image of the left atrial appendage occluder through three-dimensional reconstruction; Step 5: Based on the three-dimensional image of the left atrial appendage occluder, a three-dimensional plane of the left atrial appendage occluder, a front view of the occluder, and a plane of the left atrial appendage opening are obtained; Step 6: extracting evaluation parameters after left atrial appendage occlusion surgery, the parameters at least including: the size, location and grade of residual shunt, the location, shoulder position and height of the occluder, the degree of endothelialization of the occluder, and the location of device-related thrombus; Step 7: Evaluate the left atrial appendage occlusion effect based on the obtained evaluation parameters after left atrial appendage occlusion surgery.

2. The method for quantitatively analyzing left atrial appendage occlusion effect based on CT images according to claim 1, characterized in that: Step 3: The steps of constructing the left atrial appendage occluder segmentation model are: Step 3.1: Collect CTA images of patients after left atrial appendage occlusion surgery, segment the left atrial appendage occluder, and obtain a training data set and a corresponding mask; Step 3.2: Based on the training data set and mask obtained in step 3.1, a U-net algorithm model is trained, and the trained model is used as a left atrial appendage occluder segmentation model.

3. The method for quantitatively analyzing left atrial appendage occlusion effect based on CT images according to claim 1, characterized in that: The specific steps of step 5 include: Step 5.1: Based on the center point of the occluder rivet in the left atrial appendage occluder image as the starting point P1, the tip of the occluder as the end point P2, the path direction is P1→P2, and the connecting line from P1 to P2 is used as the initial axis of the occluder, and the axis of the occluder is continuously corrected through iterative calculation to finally obtain the actual axis of the occluder; Step 5.2: The tangent line passing through the center point of the occluder rivet and perpendicular to the initial axis is used as the tangent line of the left atrial surface of the occluder. The tangent line of the left atrial surface of the occluder is corrected while the axial direction of the occluder is iteratively calculated, and finally the actual tangent line of the left atrial surface of the occluder is obtained; Step 5.3: Fix the obtained tangent of the left atrial surface of the actual occluder and the actual axial direction of the occluder to 90°, thereby obtaining the three-dimensional planes of the left atrial appendage occluder: axial section, sagittal plane, and coronal plane; Step 5.4: The obtained axial section, coronal plane, and sagittal plane are fixed at 90° angles in pairs, and the window width and window position of the axial section are adjusted until the CT image layer of the occluder can be displayed, thereby obtaining a front view of the left atrial appendage occluder; Step 5.5: In the 3D reconstruction multiplane, use the orthogonal plane method to place the crosshairs at the level of the proximal circumflex artery; Step 5.6: Rotate the crosshairs of the coronal and sagittal planes in turn, adjust the positions of the crosshairs of the coronal and sagittal planes, and place the crosshairs of the coronal and sagittal planes at the circumflex branch and the pulmonary vein crest, respectively, so as to determine the position of the left atrial appendage opening, and use the plane corresponding to the crosshairs placed at the circumflex branch and the pulmonary vein crest as the left atrial appendage opening plane.

4. The method for quantitatively analyzing left atrial appendage occlusion effect based on CT images according to claim 1, characterized in that: Step 6 includes the following specific steps: Step 6.1: Determine the location, size, and grade of residual shunts; Step 6.2: Determine the position of the occluder, including the height and position of the shoulder; Step 6.3: Determine the contrast attenuation thickness (HAT) and endothelialization degree of the occluder; Step 6.4: Evaluate the HAT. If the HAT thickness is greater than 3 mm, observe whether the HAT is regular. If not, consider it as DRT and indicate the current DRT position by the clock method.

5. The method for quantitatively analyzing left atrial appendage occlusion effect based on CT images according to claim 4, characterized in that: The specific steps of step 6.1 are: Step 6.1.1: Rotate the crosshairs in the coronal and sagittal planes respectively, and define the path of contrast medium from the left atrium to the left atrial appendage as the residual shunt in the sagittal or coronal plane; Step 6.1.2: Determine the control line at the residual shunt based on the axial section and obtain the cross section of the residual shunt; Step 6.1.3: Determine the minimum diameter and area of ​​the residual shunt based on the cross section; Step 6.1.4: Classify the residual shunt according to its minimum diameter: if the diameter is 0-1mm, it is a trace amount; if the diameter is 1mm-3mm, it is a small amount; if the diameter is 3mm-5mm, it is a medium amount; if it is greater than 5mm, it is a large amount.

6. The method for quantitatively analyzing left atrial appendage occlusion effect based on CT images according to claim 5, characterized in that: The specific steps of step 6.2 are: Step 6.2.1: Rotate the crosshairs of the axial section until the occluder shoulder is located in the sagittal or coronal plane; Step 6.2.2: Take the left atrial appendage opening plane as the starting point and the highest position of the occluder shoulder as the end point, calculate the Euclidean distance between the two points, and use the distance as the height of the occluder shoulder.

7. The method for quantitatively analyzing left atrial appendage occlusion effect based on CT images according to claim 5, characterized in that: The specific steps of step 6.3 are: Step 6.3.1: Detect the intersection areas of all the cross beams of the left atrial appendage occluder on the three-dimensional image, and select the intersection area with the largest volume as the center point of the occluder; Step 6.3.2: Start searching from the position close to the center point of each beam. When the angle between the vector A formed by the current search point to the next search point and the vector B formed by the previous search point to the current search point is the largest, the current search point is taken as the inflection point of the beam. Step 6.3.3: Calculate the planes that can be formed by the inflection points of the beams determined in step 5.3.2, select the plane with the largest number of inflection points, and use the normal vector of the plane as the vector from the center point to the end of the occluder; if the number of inflection points belonging to each plane in the planes that can be formed by the inflection points of the beams is the same, select the plane closest to the center point of the occluder, and use the normal vector of the plane as the vector from the center point to the end of the occluder; Step 6.3.4: Using the vector from the center point to the end of the occluder determined in step 5.3.3 as the normal vector of the plane, calculate the area of ​​the quasi-circular shape enclosed by the crossbeam of the occluder on each plane, and take the plane with the largest area as the maximum cross-section of the occluder; Step 6.3.5: Segment the endothelialized area on the surface of the left atrial appendage occluder using an endothelialized area segmentation method; Step 6.3.6: plotting the endothelial thickness at each pixel in the endothelialized area using different colors; Step 6.3.7: Calculate the endothelialization ratio by the following formula and use the endothelialization ratio as the degree of endothelialization after left atrial appendage occlusion: Endothelialization ratio = endothelialization coverage area of ​​the left atrial surface of the occluder / area of ​​the left atrial surface of the occluder*100%.

8. The method for quantitatively analyzing left atrial appendage occlusion effect based on CT images according to claim 7, characterized in that: The endothelialization area segmentation method in step 6.3.5 is a grayscale threshold segmentation algorithm, and its specific steps are as follows: Step 6.3.5.1: along the two normal vectors of the maximum cross section of the occluder determined in step 6.3.4, starting from the maximum cross section of the occluder, search for pixel points that meet the endothelialization CT value range within the maximum cross section range in each layer of the image; Step 6.3.5.2: When the pixel points belonging to the left atrium area are searched, the search is stopped, and the searched pixel points are used as the pixel points of the endothelialization area, and the area formed by combining these pixel points is used as the endothelialization area.

9. The method for quantitatively analyzing left atrial appendage occlusion effect based on CT images according to claim 7, characterized in that: The endothelialization area segmentation method in step 6.3.5 is the U-net segmentation algorithm, and its specific steps are as follows: Step 1: Based on the CT image data with pre-annotated endothelialization areas and reviewed by doctors in the field of cardiology, the endothelialization area segmentation model is trained using the U-net algorithm; Step 2: Obtain the CT image of the current patient, and use the trained endothelialization region segmentation model to segment the endothelialization region in the image.

10. A system for extracting left atrial appendage data parameters based on CT images, implemented based on the method of claim 1, characterized in that: The system comprises: An image sequence acquisition module is used to acquire CTA images of the heart of a patient after left atrial appendage occlusion surgery; An image reconstruction module performs three-dimensional reconstruction on the cardiac CTA image sequence to obtain a three-dimensional cardiac image; Segmentation module, including, A left atrium segmentation unit, used for segmenting a three-dimensional image of the left atrium using a left atrium segmentation model; A left atrial appendage occluder segmentation unit, used for segmenting the left atrial appendage occluder region in the CTA image using the left atrial appendage occluder segmentation model; A three-dimensional reconstruction module is used to construct a three-dimensional model of the left atrial appendage occluder based on the segmented left atrial appendage occluder area, and obtain a three-dimensional image of the left atrial appendage occluder through three-dimensional reconstruction; A three-dimensional plane acquisition module is used to acquire the three-dimensional plane of the left atrial appendage occluder, the front view of the occluder and the left atrial appendage opening plane based on the three-dimensional image of the left atrial appendage occluder; The occluder parameter extraction module is used to extract the evaluation parameters after left atrial appendage occlusion surgery, and the parameters include at least: the size, location and grade of residual shunt, the location, shoulder position and height of the occluder, the degree of endothelialization of the occluder, and the location of device-related thrombus; The evaluation module is used to evaluate the left atrial appendage occlusion effect based on the evaluation parameters obtained after the left atrial appendage occlusion operation.

Images