A method and device for automatically extracting morphological parameters of a vascular stent

Abstract

The invention discloses a method and device for automatically extracting morphological parameters of a vascular stent. The method comprises the following steps: obtaining a binary image of a vascular stent; generating a connected model of a stent ring after performing connected region analysis on the binary image; calculating the centroid coordinates of the stent ring; interpolating to obtain a center line of the stent ring; traversing all voxel points of each connected model, searching on the center line of the stent ring to obtain the closest point corresponding to each voxel point; calculating the tangent vector of each closest point, and using the tangent vector as a direction vector; checking whether there is a voxel point in the same direction as the voxel point in the same stent ring on the direction vector of each voxel point, if not, determining the voxel point as a peak point of the stent ring; determining the displacement of the centroid coordinates; using the distance between the maximum peak points as the characteristic diameter of the stent ring, and determining the periodic annularity after comparing the characteristic diameters of the stent rings at two different periods; and using the mean value of the deflection angles of all the peak points on the same stent ring as the annular deflection angle.

Description

Technical Field

[0001] The invention belongs to the technical field of medical image analysis, and in particular relates to a method and a device for automatically extracting morphological parameters of a vascular stent. Background Art

[0002] Vascular stents are a type of support made of a variety of materials, mainly metal, and are mostly used to treat cardiovascular diseases such as aortic dissection, myocardial infarction, and abdominal aortic aneurysm. Vascular stents can effectively separate the true and false lumens of blood vessels, promote the restoration of normal blood flow, effectively reduce the risk of aneurysm rupture, and cause benign remodeling of the false lumen.

[0003] Morphological parameters of vascular stents, such as circumferential deflection, axial displacement, and inlet and outlet contraction ratio, are important reference indicators for clinical monitoring of stent implantation and evaluation of prognosis and efficacy. At present, the acquisition of morphological parameters of vascular stents mainly relies on manual measurement on images after artificial modeling. This method is not only time-consuming and error-prone, but also has a high time cost and low accuracy in the extraction process. In addition, the measurement results vary from person to person and lack consistency. In addition, highly complex morphological parameters cannot be manually counted, and as the scale of parameters gradually increases, the accuracy of the data extracted by this manual measurement method will drop rapidly.

[0004] In view of this, an automatic, fast and accurate method for constructing and extracting morphological parameters of vascular stents is urgently needed. Summary of the invention

[0005] The purpose of the present invention is to overcome one or more deficiencies of the prior art and to provide a method and device for automatically extracting morphological parameters of a vascular stent.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] First aspect

[0008] A first aspect of the present invention provides a method for automatically extracting morphological parameters of a vascular stent, comprising the following steps:

[0009] Acquire a binary image of the vascular stent;

[0010] Performing connected region analysis on the binary image, and generating a connected model of each stent ring on the vascular stent after the connected region analysis;

[0011] Calculate the centroid coordinates of each stent ring;

[0012] The centroid of each stent ring is interpolated based on the polynomial interpolation method, and the center line of the stent ring is obtained after interpolation;

[0013] Traverse all voxel points of each stent ring connected model, and search on the center line of the stent ring to obtain the closest point corresponding to each voxel point, and the closest point of any voxel point is the point located on the center line of the stent ring and closest to the voxel point;

[0014] Calculate the tangent vector of each of the closest points, and use the tangent vector as the direction vector of the voxel point corresponding to the closest point, wherein any tangent vector of the closest point is a tangent vector of the center line of the stent ring passing through the closest point, and the direction of the tangent vector points to the side of the center line of the stent ring close to the voxel point corresponding to the closest point;

[0015] Check whether each voxel point in the neighborhood of each voxel point is a first voxel point. If all voxel points in the neighborhood are not the first voxel point, the checked voxel point is determined as the peak point of the stent ring where it is located, wherein the first voxel point is a voxel point where the angle between the vector formed by the checked voxel point pointing to the first voxel point itself and the direction vector of the checked voxel point is less than or equal to 90 degrees;

[0016] Performing vector registration on the vascular stents in multiple periods, and determining the centroid coordinate displacement of each stent ring in two different periods after vector registration, wherein the centroid coordinate displacement is used to characterize the slip characteristics of the stent ring;

[0017] Calculate the distance between each peak point on each stent ring, where the distance between the peak points is the distance between two peak points in the same stent ring;

[0018] The distance between the maximum peak points is taken as the characteristic diameter of the stent ring, and the characteristic diameters of the stent ring at two different periods are compared to determine the inter-periodic ring rate of the stent ring, and the inter-periodic ring rate is used to characterize the contraction characteristics of the stent ring;

[0019] The deflection angles of all peak points on each stent ring are calculated, and the average of the deflection angles of all peak points on the same stent ring is taken as the circumferential deflection angle of the stent ring, and the circumferential deflection angle is used to characterize the circumferential deflection characteristics of the stent ring.

[0020] Preferably, when performing connected region analysis on the binary image, small connected regions with a number of voxel points less than a first preset value are deleted.

[0021] Preferably, the first preset value is 200.

[0022] Preferably, the polynomial interpolation method is a cubic spline interpolation method.

[0023] Preferably, when performing vector registration on the vascular stents at multiple stages, a bone positioning point is selected as a registration reference point, and vector registration of the vascular stents at multiple stages is performed based on the registration reference point.

[0024] Preferably, the centroid coordinates of each stent ring are calculated based on a first formula, wherein the first formula is:

[0025] ;

[0026] in, represents the x-coordinate component of the centroid coordinates, represents the y-coordinate component of the centroid coordinates, represents the z-coordinate component of the centroid coordinates, N represents the total number of voxel points contained in the connectivity model of a stent ring, i represents the subscript number of the voxel point, represents the x-coordinate component of the voxel point with subscript number i, represents the y-coordinate component of the voxel point with subscript number i, Represents the z-coordinate component of the voxel point with subscript number i.

[0027] Preferably, after the vector alignment, the displacement of the center of mass coordinates of each stent ring during two different periods is determined based on a second formula, wherein the second formula is:

[0028] ;

[0029] in, represents the x-direction displacement component of the center of mass coordinate of the bracket ring between the first period h and the second period j, represents the y-direction displacement component of the center of mass coordinate of the bracket ring between the first period h and the second period j, represents the z-direction displacement component of the center of mass coordinate of the bracket ring between the first period h and the second period j, represents the x-coordinate component of the center of mass of the bracket ring at the first period h, represents the x-coordinate component of the center of mass of the support ring at the second period j, represents the y-coordinate component of the center of mass of the support ring at the first period h, represents the y-coordinate component of the center of mass of the support ring at the second period j, represents the z-coordinate component of the center of mass of the support ring at the first period h, Represents the z-coordinate component of the center of mass coordinate of the support ring at the second period j.

[0030] Preferably, the characteristic diameter ,in, and Respectively represent two different peak points on the same stent ring. Indicates the distance between peak points;

[0031] The cycle rate during the period ,in, represents the characteristic diameter of the stent ring at the kth period, Represents the characteristic diameter of the stent ring in the first period, k>1.

[0032] Preferably, the step of calculating the deflection angles of all peak points on each bracket ring and taking the average of the deflection angles of all peak points on the same bracket ring as the circumferential deflection angle of the bracket ring specifically includes the following sub-steps:

[0033] Determine the projection plane of the support ring I, the normal vector direction of the projection plane is the direction of the center-of-mass vector, wherein I represents the number of the support ring, and the center-of-mass vector is the line vector connecting the center of mass of the support ring numbered I-1 and the center of mass of the support ring numbered I+1;

[0034] Project all peak points on the stent ring 1 at two different periods and the centroid of the stent ring 1 onto the projection plane to obtain the projection points corresponding to each peak point and the projection points of the centroid of the stent ring 1;

[0035] Align and register all projection points of the stent ring I at two different stages on the projection plane;

[0036] Calculate the deflection angle of each peak point , where q represents the number of the peak point, represents the vector between the centroids, represents the modulus of the vector between the centroids, represents the vector formed by the projection point of the peak point numbered q on the support ring I in the previous period and the projection point of the center of mass of the support ring I in two different periods, represents the vector formed by the projection point of the peak point numbered q on the support ring I in the later period in two different periods and the projection point of the center of mass of the support ring I, Represents vector The modulus value, Represents vector The modulus value of

[0037] Calculate the mean of the deflection angles of all peak points on the bracket ring I, and use the mean as the annular deflection angle of the bracket ring I, where the annular deflection angle of the bracket ring I is , M represents the total number of peak points on the stent ring I.

[0038] The beneficial effects brought about by the first aspect of the present invention are:

[0039] (1) Based on the calculation and analysis of the spatial connectivity of the binary image of the vascular stent, the connectivity model of each stent ring on the vascular stent is obtained, thereby completing the automatic modeling of the vascular stent. After the automatic modeling is completed, the basic data set on each stent ring is extracted with the stent ring as the unit. The basic data set includes the centroid coordinates, the center line of the stent ring and each peak point. The basic data set is used as the feature marker point, and then the morphological parameters are constructed and calculated based on these feature marker points, thereby obtaining three morphological parameters: the stent ring displacement vector (characterized by the centroid coordinate displacement of the stent ring), the stent ring rebound size (characterized by the stent ring period ring rate) and the stent ring circumferential deflection size (characterized by the circumferential deflection angle of the stent ring). The automatic extraction of morphological parameters of vascular stents of different complexity is realized, and the speed, accuracy and stability of the morphological parameter extraction of the vascular stent are improved;

[0040] At the same time, the automatic extraction method of morphological parameters provided in the first aspect of the present invention constructs and analyzes morphological parameters of various complexities based on the combination of characteristic marker points, so that various morphological parameters of the vascular stent can be formed by the combination of characteristic marker points, and therefore has extremely strong applicability; the morphological parameters obtained by characteristic marker points and various combinations can help clinicians to accurately monitor the implantation status and prognostic deformation characteristics of vascular stents, and therefore also have extremely strong clinical applicability; during clinical analysis, if other morphological parameters are needed, they can be quickly obtained.

[0041] (2) The accuracy of the stent ring centerline interpolation is improved by using the cubic spline interpolation method;

[0042] (3) By deleting discontinuous small connected areas with a number of voxel points less than a first preset value, interference with the connected model of each stent ring on the vascular stent is reduced.

[0043] Second aspect

[0044] The second aspect of the present invention provides an automatic extraction device for morphological parameters of a vascular stent, comprising a memory and a processor, wherein the memory is used to store a method for automatically extracting morphological parameters of a vascular stent described in the first aspect of the present invention, and the processor is used to call a method for automatically extracting morphological parameters of a vascular stent stored in the memory to automatically extract the morphological parameters of the vascular stent.

[0045] The second aspect of the present invention brings the same beneficial effects as the first aspect of the present invention, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A flow chart of a method for automatically extracting morphological parameters of a vascular stent;

[0047] Figure 2 A two-dimensional unfolding schematic diagram of the peak point marking on the stent ring;

[0048] Figure 3 A schematic diagram of the peak points selected on the stent ring;

[0049] Figure 4 A schematic diagram of vector registration during vascular stenting;

[0050] Figure 5 It is a schematic diagram of the coordinate displacement of the center of mass of the stent ring at the end of the vascular stent;

[0051] Figure 6 A schematic diagram of the characteristic diameter of the stent ring;

[0052] Figure 7 A schematic diagram of a calculation process of the circumferential deflection angle of the stent ring;

[0053] Figure 8 It is a visual diagram of the change of the annular deflection angle of the bracket ring over a long period of time. DETAILED DESCRIPTION

[0054] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0055] Embodiment 1

[0056] See also Figure 1-Figure 8 This embodiment provides a method for automatically extracting morphological parameters of a vascular stent, which specifically includes the following steps:

[0057] S1. Obtain a binary image of the vascular stent. Specifically, based on the collection of CT dicom data, an image file containing the vascular stent is obtained, and then artificial multi-target segmentation and binarization processing are performed to obtain a binary image of the vascular stent.

[0058] S2, performing connected region analysis on the binary image, and generating a connected model of each stent ring on the vascular stent after the connected region analysis. As a preferred embodiment, when performing connected region analysis on the binary image, small discontinuous connected regions with a voxel number less than a first preset value are deleted, and the first preset value is preferably 200.

[0059] S3. Calculate the centroid coordinates of each bracket ring.

[0060] Optionally, in step S3, the centroid coordinates of each stent ring are calculated based on a first formula, and the first formula is specifically:

[0061] ;

[0062] in, represents the x-coordinate component of the centroid coordinates, represents the y-coordinate component of the centroid coordinates, represents the z-coordinate component of the centroid coordinates, N represents the total number of voxel points contained in the connectivity model of a stent ring, i represents the subscript number of the voxel point, represents the x-coordinate component of the voxel point with subscript number i, represents the y-coordinate component of the voxel point with subscript number i, Represents the z-coordinate component of the voxel point with subscript number i.

[0063] S4. Interpolate the centroid of each stent ring based on the polynomial interpolation method, and obtain the center line of the stent ring after interpolation.

[0064] Optionally, the polynomial interpolation method is a cubic spline interpolation method. Specifically, the cubic spline interpolation method is based on the cubic spline interpolation method in the common embodiment. The cubic spline interpolation method is also called a five-point cubic interpolation method, which is a method for performing piecewise fitting on a discrete point set using a cubic polynomial.

[0065] S5. Traverse all voxel points of each stent ring connected model, and search on the center line of the stent ring to obtain the closest point corresponding to each voxel point. The closest point of any voxel point refers to the point located on the center line of the stent ring and closest to the voxel point. Specifically, search for the closest point corresponding to each voxel point. The closest point of a voxel point is located on the center line of the stent ring and is closest to the voxel point.

[0066] S6. Calculate the tangent vector of each closest point and use the tangent vector as the direction vector of the voxel point corresponding to the closest point, wherein any tangent vector of the closest point is a tangent vector of the center line of the stent ring passing through the closest point, and the direction of the tangent vector points to the side of the center line of the stent ring close to the voxel point corresponding to the closest point.

[0067] S7. Check whether each voxel point in the neighborhood of each voxel point is the first voxel point. If all the voxel points in the neighborhood are not the first voxel point, the checked voxel point is determined as the peak point of the stent ring where it is located, wherein the first voxel point is a voxel point where the angle between the vector formed by the checked voxel point pointing to the first voxel point itself and the direction vector of the checked voxel point is less than or equal to 90 degrees. Specifically, the neighborhood of a voxel point refers to the neighborhood of the voxel point on the stent ring connectivity model (the neighborhood in the connected region analysis when generating the stent ring connectivity model), and the first voxel point is also referred to as a voxel point that is in the neighborhood of the checked voxel point and has the same direction as the checked voxel point. Combined with Figure 2 The same direction is explained as follows: if the angle between the vector formed by the inspected voxel point Pi pointing to a voxel point in the neighborhood of the inspected voxel point Pi and the direction vector of the inspected voxel point Pi is less than or equal to 90 degrees, then the voxel point in the neighborhood of the inspected voxel point Pi is the voxel point in the same direction as the inspected voxel point Pi, for example Figure 2 The voxel point marked as A has voxel points A5 and A4 in the same direction, so the voxel point marked as A is not the peak point of the stent ring. The voxel point marked as B has voxel points B1 and B6 in the same direction, so the voxel point marked as B is not the peak point of the stent ring. The voxel point marked as G has voxel points G5 and G1 in the same direction, so the voxel point marked as G is not the peak point of the stent ring. The voxel points marked as C, D and E do not have voxel points in the same direction, so the voxel points marked as C, D and E are the three peak points of the stent ring, among which, the voxel points marked as The voxel points of C1, C2 and C3 are voxel points in the neighborhood of the voxel point marked as C, the voxel points marked as A1, A2, A3, A4 and A5 are voxel points in the neighborhood of the voxel point marked as A, the voxel points marked as B1, B2, B3, B4, B5 and B6 are voxel points in the neighborhood of the voxel point marked as B, the voxel points marked as G1, G2, G3, G4 and G5 are voxel points in the neighborhood of the voxel point marked as G, and the voxel points marked as E1, E2 and E3 are voxel points in the neighborhood of the voxel point marked as E. In addition, in this step, the peak points of the same stent ring determined are combined into a peak point set, and each stent ring corresponds to its own peak point set.

[0068] S8. Perform vector registration on the vascular stents in multiple periods, and determine the centroid coordinate displacement of each stent ring in two different periods after vector registration, and the centroid coordinate displacement is used to characterize the slip characteristics of the stent ring. The above periods are the follow-up periods of the cases with the vascular stents installed.

[0069] Optionally, in step S8, when performing vector registration on the vascular stents at multiple stages, the bone positioning point is selected as the registration reference point, and the vector registration of the vascular stents at multiple stages is performed based on the registration reference point. Figure 4 As shown, the vascular stent is in the T1 follow-up period, the T2 follow-up period and the T3 follow-up period from left to right, and the rightmost vector registration result image is obtained based on the bone positioning point as the registration reference point.

[0070] Optionally, in step S8, after the vector alignment, the displacement of the centroid coordinates of each stent ring during two different time periods is determined based on a second formula, and the second formula is specifically:

[0071] ;

[0072] in, represents the x-direction displacement component of the center of mass coordinate of the bracket ring between the first period h and the second period j, represents the y-direction displacement component of the center of mass coordinate of the bracket ring between the first period h and the second period j, represents the z-direction displacement component of the center of mass coordinate of the bracket ring between the first period h and the second period j, represents the x-coordinate component of the center of mass of the bracket ring at the first period h, represents the x-coordinate component of the center of mass of the support ring at the second period j, represents the y-coordinate component of the center of mass of the support ring at the first period h, represents the y-coordinate component of the center of mass of the support ring at the second period j, represents the z-coordinate component of the center of mass of the support ring at the first period h, Represents the z-coordinate component of the center of mass coordinate of the support ring at the second period j. Figure 5 The figure shows the position diagram of the stent ring at the end of the vascular stent at three different periods, from left to right, the position diagram at the first period, the position diagram at the second period and the position diagram at the third period. It can be seen from the figure that the stent ring at the end of the vascular stent slipped between the second period and the first period, and also slipped between the third period and the second period. The slip amount between the second period and the first period is d1 (the centroid coordinate of the stent ring is from P O1 Moved to P O2 ), the slip amount that occurs during the third period and the second period is d2 (the coordinates of the center of mass of the bracket ring are from P O2 Moved to P O3 ), based on which the sliding characteristic quantity of the stent ring located at the entrance and exit of the vascular stent which is commonly seen in clinical practice is constructed and analyzed, which is one of the morphological parameters constructed in this embodiment: the displacement of the centroid coordinate of the stent ring.

[0073] S9. Calculate the distance between each peak point on each stent ring. The distance between peak points is the distance between two peak points in the same stent ring. Figure 6 The distances between the peak points on the stent ring at the top of the vascular stent, the stent ring at the middle of the vascular stent, and the stent ring at the bottom of the vascular stent are shown. Among them, the peak point set of the stent ring at the middle of the vascular stent includes five peak points, which are peak points P MA , peak point P MB , peak point P MC , peak point P MD and the peak point P ME , calculate the distance between two peak points in turn, and obtain a total of ten distances between peak points. The peak point set of the stent ring at the uppermost or lowermost end of the vascular stent includes eight peak points, and the eight peak points are peak points P MF , peak point P MG , peak point P MH , peak point P MI , peak point P MJ、 Peak point P MK , peak point P ML and the peak point P MM , calculate the distance between two peak points in sequence, and get a total of twenty-eight distances between peak points.

[0074] S10. Taking the distance between the maximum peak points as the characteristic diameter of the stent ring, and comparing the characteristic diameters of the stent ring at two different periods, the inter-periodic ring rate of the stent ring is determined. The inter-periodic ring rate is used to characterize the contraction characteristics of the stent ring.

[0075] Optionally, in step S10, the characteristic diameter ,in, and Respectively represent two different peak points on the same stent ring. Indicates the distance between peak points. , where k>1, represents the characteristic diameter of the stent ring at the kth period. It represents the characteristic diameter of the stent ring in the first period, also called the first follow-up period of the case. The contraction characteristic quantities of each stent ring of the common clinical vascular stent are constructed and analyzed, which is the second morphological parameter constructed in this embodiment: the inter-periodic ring rate of the stent ring.

[0076] S11. Calculate the deflection angles of all peak points on each bracket ring, and take the average of the deflection angles of all peak points on the same bracket ring as the annular deflection angle of the bracket ring. The annular deflection angle is used to characterize the circumferential deflection characteristics of the bracket ring.

[0077] As a preferred embodiment, in step S11, the deflection angles of all peak points on each bracket ring are calculated, and the average of the deflection angles of all peak points on the same bracket ring is used as the circumferential deflection angle of the bracket ring, which specifically includes the following sub-steps:

[0078] S001. Determine the projection plane of the support ring I. The direction of the normal vector of the projection plane is the direction of the center-of-mass vector, where I represents the number of the support ring. The above-mentioned center-of-mass vector is the line vector connecting the center of mass of the support ring numbered I-1 and the center of mass of the support ring numbered I+1.

[0079] S002. Project all peak points on the support ring I at two different periods and the center of mass of the support ring I onto the projection plane to obtain the projection points corresponding to each peak point and the projection points of the center of mass of the support ring I.

[0080] S003. Align and register the stent ring I at two different stages at all projection points on the projection plane.

[0081] S004. Calculate the deflection angle of each peak point , where q represents the number of the peak point, represents the vector between the centroids, represents the modulus of the vector between the centroids, represents the vector formed by the projection point of the peak point numbered q on the support ring I in the previous period and the projection point of the center of mass of the support ring I in two different periods, represents the vector formed by the projection point of the peak point numbered q on the support ring I in the later period in two different periods and the projection point of the center of mass of the support ring I, Represents vector The modulus value, Represents vector The modulus value of .

[0082] S005, calculating the mean of the deflection angles of all the peak points on the bracket ring I, and taking the mean as the annular deflection angle of the bracket ring I, wherein the annular deflection angle of the bracket ring I is , M represents the total number of peak points on the stent ring I.

[0083] Figure 7The projections of the peak points on the same stent ring on the projection plane βplane when the two different periods are shown, the two different periods are the previous period T1 and the later period T2, and based on the determined reference origin, the alignment and registration of the projection points are performed, and then the deflection angle of each peak point is calculated based on the position of each projection point after the alignment and registration, and then the average of the deflection angles of all peak points on a stent ring is obtained, and the average is defined as the circumferential deflection angle of the stent ring. Based on this, the circumferential deflection feature of each stent ring on the clinically common vascular stent is constructed and analyzed, which is the third morphological parameter constructed in this embodiment: the circumferential deflection angle of the stent ring.

[0084] Figure 8 The circumferential deflection angle of the vascular stent during four consecutive time periods was visualized. It can be seen from the figure that through the construction and analysis of the circumferential deflection angle in the morphological parameters, the changes in the circumferential deflection characteristic quantity of the stent ring can be intuitively obtained during clinical follow-up of cases, which is convenient for the evaluation of the prognostic deformation characteristics of the vascular stent.

[0085] Embodiment 2

[0086] The first embodiment provides a device for automatically extracting morphological parameters of a vascular stent, which is loaded with the method for automatically extracting morphological parameters of a vascular stent implemented in the first embodiment, and automatically extracts morphological parameters of the vascular stent based on the loading of the method. Specifically, the device for automatically extracting morphological parameters of a vascular stent includes a memory and a processor, the memory is used to store the method for automatically extracting morphological parameters of the vascular stent in the first embodiment, and the processor is used to call the method stored in the memory to automatically extract morphological parameters of the vascular stent.

[0087] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for automatically extracting morphological parameters of vascular stents. It is characterized in that The steps include: Acquire a binary image of the vascular stent; Performing connected region analysis on the binary image, and generating a connected model of each stent ring on the vascular stent after the connected region analysis; Calculate the centroid coordinates of each stent ring; The centroid of each stent ring is interpolated based on the polynomial interpolation method, and the center line of the stent ring is obtained after interpolation; Traverse all voxel points of each stent ring connected model, and search on the center line of the stent ring to obtain the closest point corresponding to each voxel point, and the closest point of any voxel point is the point located on the center line of the stent ring and closest to the voxel point; Calculate the tangent vector of each of the closest points, and use the tangent vector as the direction vector of the voxel point corresponding to the closest point, wherein any tangent vector of the closest point is a tangent vector of the center line of the stent ring passing through the closest point, and the direction of the tangent vector points to the side of the center line of the stent ring close to the voxel point corresponding to the closest point; Check whether each voxel point in the neighborhood of each voxel point is a first voxel point. If all voxel points in the neighborhood are not the first voxel point, the checked voxel point is determined as the peak point of the stent ring where it is located, wherein the first voxel point is a voxel point where the angle between the vector formed by the checked voxel point pointing to the first voxel point itself and the direction vector of the checked voxel point is less than or equal to 90 degrees; Performing vector registration on the vascular stents in multiple periods, and determining the centroid coordinate displacement of each stent ring in two different periods after vector registration, wherein the centroid coordinate displacement is used to characterize the slip characteristics of the stent ring; Calculate the distance between each peak point on each stent ring, where the distance between the peak points is the distance between two peak points in the same stent ring; The distance between the maximum peak points is taken as the characteristic diameter of the stent ring, and the characteristic diameters of the stent ring at two different periods are compared to determine the inter-periodic ring rate of the stent ring, and the inter-periodic ring rate is used to characterize the contraction characteristics of the stent ring; The deflection angles of all peak points on each stent ring are calculated, and the average of the deflection angles of all peak points on the same stent ring is taken as the circumferential deflection angle of the stent ring, and the circumferential deflection angle is used to characterize the circumferential deflection characteristics of the stent ring.

2. A method for automatically extracting morphological parameters of a vascular stent according to claim 1, It is characterized in that When performing connected region analysis on the binary image, small connected regions with a number of voxel points less than a first preset value are deleted.

3. A method for automatically extracting morphological parameters of a vascular stent according to claim 2, It is characterized in that The first preset value is 200.

4. The method for automatically extracting morphological parameters of a vascular stent according to claim 1, It is characterized in that The polynomial interpolation method is a cubic spline interpolation method.

5. The method for automatically extracting morphological parameters of a vascular stent according to claim 1, It is characterized in that When performing vector registration on the vascular stents at multiple stages, the bone positioning points are selected as registration reference points, and the vector registration of the vascular stents at multiple stages is performed based on the registration reference points.

6. The method for automatically extracting morphological parameters of a vascular stent according to claim 1, It is characterized in that The centroid coordinates of each bracket ring are calculated based on the first formula, which is: ； in, represents the x-coordinate component of the centroid coordinates, represents the y-coordinate component of the centroid coordinates, represents the z-coordinate component of the centroid coordinates, N represents the total number of voxel points contained in the connectivity model of a stent ring, i represents the subscript number of the voxel point, represents the x-coordinate component of the voxel point with subscript number i, represents the y-coordinate component of the voxel point with subscript number i, Represents the z-coordinate component of the voxel point with subscript number i.

7. The method for automatically extracting morphological parameters of a vascular stent according to claim 1, It is characterized in that After the vector alignment, the displacement of the center of mass coordinates of each stent ring during two different time periods is determined based on the second formula, and the second formula is: ； in, represents the x-direction displacement component of the center of mass coordinate of the bracket ring between the first period h and the second period j, represents the y-direction displacement component of the center of mass coordinate of the bracket ring between the first period h and the second period j, represents the z-direction displacement component of the center of mass coordinate of the bracket ring between the first period h and the second period j, represents the x-coordinate component of the center of mass of the bracket ring at the first period h, represents the x-coordinate component of the center of mass of the support ring at the second period j, represents the y-coordinate component of the center of mass of the support ring at the first period h, represents the y-coordinate component of the center of mass of the support ring at the second period j, represents the z-coordinate component of the center of mass of the support ring at the first period h, Represents the z-coordinate component of the center of mass coordinate of the support ring at the second period j.

8. The method for automatically extracting morphological parameters of a vascular stent according to claim 1, It is characterized in that The characteristic diameter ,in, and Respectively represent two different peak points on the same stent ring. Indicates the distance between peak points; The cycle rate during the period ,in, represents the characteristic diameter of the stent ring at the kth period, Represents the characteristic diameter of the stent ring in the first period, k>

1.

9. The method for automatically extracting morphological parameters of a vascular stent according to claim 1, It is characterized in that The step of calculating the deflection angles of all peak points on each bracket ring and taking the average of the deflection angles of all peak points on the same bracket ring as the circumferential deflection angle of the bracket ring specifically includes the following sub-steps: Determine the projection plane of the support ring I, the normal vector direction of the projection plane is the direction of the center-of-mass vector, wherein I represents the number of the support ring, and the center-of-mass vector is the line vector connecting the center of mass of the support ring numbered I-1 and the center of mass of the support ring numbered I+1; Project all peak points on the stent ring 1 at two different periods and the centroid of the stent ring 1 onto the projection plane to obtain the projection points corresponding to each peak point and the projection points of the centroid of the stent ring 1; Align and register all projection points of the stent ring I at two different stages on the projection plane; Calculate the deflection angle of each peak point , where q represents the number of the peak point, represents the vector between the centroids, represents the modulus of the vector between the centroids, represents the vector formed by the projection point of the peak point numbered q on the support ring I in the previous period and the projection point of the center of mass of the support ring I in two different periods, represents the vector formed by the projection point of the peak point numbered q on the support ring I in the later period in two different periods and the projection point of the center of mass of the support ring I, Represents vector The modulus value, Represents vector The modulus value of Calculate the mean of the deflection angles of all peak points on the bracket ring I, and use the mean as the annular deflection angle of the bracket ring I, where the annular deflection angle of the bracket ring I is , M represents the total number of peak points on the stent ring I.

10. A device for automatically extracting morphological parameters of vascular stents, It is characterized in that It comprises a memory and a processor, wherein the memory is used to store a method for automatically extracting morphological parameters of a vascular stent as described in any one of claims 1 to 9, and the processor is used to call the method for automatically extracting morphological parameters of a vascular stent stored in the memory to automatically extract the morphological parameters of the vascular stent.

Images