A new method for measuring the degree of tear and twist of aortic dissection

Abstract

The application discloses a kind of new aortic dissection tear twist degree measuring method, belong to clinical medical technical field, B type aortic dissection refers to the intima of descending aorta is torn, blood flow is propagated along the longitudinal direction of aorta through intimal break, and forms true cavity and false lumen.False lumen refers to the newly formed lumen after intimal tear.At present, there is lack of quantitative false lumen twist degree analysis index in domestic and foreign researches.Firstly, the CT angiography axial position sequence of patient when being diagnosed is acquired, and a space orthogonal rectangular coordinate system is established after being introduced into measurement software, the false lumen position and dissection longitudinal tear length are determined, the three-dimensional coordinates of target points are sequentially measured from the axial position image from the tear starting point to the end point, the three-dimensional coordinates of all measurement points are exported, and the false lumen twist degree related indexes are sequentially calculated.The above-mentioned patent has the following beneficial effects: by using the above-mentioned measurement scheme, the purpose of measuring the false lumen twist degree of B type aortic dissection can be achieved, and evaluation indexes are provided for further exploring the false lumen twist rule.

Description

Technical Field

[0001] This invention belongs to the field of clinical medical technology, specifically relating to a novel method for measuring the degree of torsion in aortic dissection. Background Technology

[0002] Aortic dissection is a serious cardiovascular emergency that severely endangers public health, with an acute mortality rate as high as 60%–70%. Stanford Type B Aortic Dissection (TBAD) refers to a tear in the intima of the descending aorta, allowing blood flow to propagate longitudinally along the aorta through the intimal tear, forming a true lumen (TL) and a false lumen (FL). The false lumen is the newly formed lumen after the intimal tear. The false lumen spirals longitudinally around the true lumen along the aorta. Accurately understanding and quantifying the degree of tortuosity, combined with patient clinical data and disease outcomes, may help identify high-risk patients and predict adverse clinical events.

[0003] Currently, there is very little research on the degree of tortuosity of the false lumen in aortic dissection by scholars both domestically and internationally. The difficulty lies in the inability to accurately describe this spiral structure, and the lack of relevant indicators makes it only suitable for clinical research. Bondesson et al. reported two methods for measuring the tortuosity angle of the true lumen, but these two methods are based solely on the tortuosity angle, which has limited effectiveness in describing the complex three-dimensional structure of aortic dissection.

[0004] Therefore, in order to correctly understand the spiral morphology of aortic dissection, identify high-risk patients before surgery, and provide evidence for planning surgical procedures and predicting outcomes, it is urgent to design a measurement method that can accurately and comprehensively measure the degree of tortuosity of the false lumen in type B aortic dissection. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a novel method for determining the degree of torsion in aortic dissection.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] This measurement method consists of two steps: determining the three-dimensional coordinates and calculating the degree of distortion of the false cavity.

[0008] The first step is to determine the three-dimensional coordinates of each point: This measurement method is based on CT angiography images of patients diagnosed with aortic dissection. After importing the DICOM format images into the free and open-source software 3D Slicer, a three-dimensional orthogonal rectangular coordinate system is established to determine the location of the false lumen and the range of the dissection tear length. In the axial sequence, the three-dimensional coordinates of the following three points are determined sequentially at the initiation of the dissection tear: the two intersection points A and B between the false lumen and the aortic wall, and any point C on the aortic wall curve where the false lumen is located. Figure 1As shown. The coordinates of three points in each axial sequence image within the tear area were measured sequentially and exported as a text document.

[0009] The second step is to calculate the degree of distortion of the false cavity: Import the stored text document into software R, and calculate the three-dimensional coordinates of the center O of the circle determined by the three points A, B, and C on each measurement plane, based on analytical geometry and polar coordinates. Figure 2 As shown, a polar coordinate system is established for all measured planes with the calculated center O as the pole and the horizontal direction to the right as the polar axis (OX). The counterclockwise direction is defined as the positive direction. The rectangular coordinates of the measured points ABC are converted into polar coordinates. It can be seen that the angle ∠θ between each of the three points ABC on the plane and the polar axis is... A , ∠θ B and ∠θ C Then ∠θ A , ∠θ B The angle bisector of the angle and the polar axis, ∠θ (inclusive of θ) C The angle on one side) is the torsion angle of this planar pseudo-cavity, and the coordinates of the intersection point M of angle θ and circle O are calculated, such as... Figure 3 , Figure 4 As shown. Based on all measurement points A, B, O, M and angle ∠θ of this patient. A , ∠θ B , ∠θ C The pseudo-cavity torsion index, tear percentage, cumulative torsion degree, average rate of change, and standard deviation of torsion angle can be calculated using ∠θ.

[0010] The beneficial effects of this invention are:

[0011] This invention, by employing the above-described measurement scheme, can measure the degree of tortuosity of the false lumen in type B aortic dissection, providing an evaluation index for further investigation of the tortuosity pattern of the false lumen. It is simple, convenient, and practical. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This invention is a patient CT angiography axial sequence, with points A, B, and C being the measurement points on this measurement plane.

[0014] Figure 2 This is the polar coordinate system of the present invention, with OX as the polar axis, and points A, B, O, M and angle ∠θ. A , ∠θ B , ∠θ C , ∠θ M ;

[0015] Figure 3 This is a three-dimensional schematic diagram of the patient's aorta and all measurement points according to the present invention. Figure I ;

[0016] Figure 4 This is a three-dimensional schematic diagram of the patient's aorta and all measurement points according to the present invention. Figure II ;

[0017] Figure 5 This is a schematic diagram of the pseudo-cavity torsion index of the present invention;

[0018] Figure 6 This is a schematic diagram showing the percentage of tearing in the false cavity of the present invention;

[0019] Figure 7 This is a line graph showing the cumulative torsion degree of the pseudo-cavity in this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The technical solution of the present invention will now be further described. The following specific embodiments illustrate the use of the present invention. The technical means used in the embodiments are conventional means well known to those skilled in the art.

[0022] Please see the appendix Figure 1-7 It should be noted that the coordinates, lines, angles, etc., shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modification to the measuring structure, change in the proportional relationship, or adjustment of the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0023] Referring to the measurement method shown in the attached figures, the process and principle of this invention consist of two steps: determining the three-dimensional coordinates and calculating the degree of distortion of the false cavity, as detailed below:

[0024] The first step is to determine the three-dimensional coordinates of each point: First, obtain the CT angiography sequence of the patient diagnosed with type B aortic dissection. Import the DICOM image format into the 3D Slicer software, establish an orthogonal three-dimensional rectangular coordinate system, and select the thinnest axial sequence as the measurement sequence. Identify the false lumen based on the relative relationship between the true lumen and the false lumen, using the initiation point of the dissection tear as the starting point, such as... Figure 1 As shown, points A, B, and C are the measurement points on this plane. It can be seen that the intima-lamella intersects the vessel wall at points A and B. Take any point C on the lateral curve of the aortic vessel wall in the false lumen, and sequentially measure the three-dimensional coordinates of these three points, denoted as A1, B1, and C1. This completes the plane measurement. Figure 1 As shown. Measurements are then taken at fixed intervals downwards for each subsequent plane. Due to the intricate anatomical changes in aortic dissection, this interval must be <5mm to ensure measurement accuracy. It is important to note that the relative relationships between points A and B must not be confused when measuring in the next plane. These are sequentially labeled A1, B1, C1, A2, B2, C2…A n B n C n (Where, n represents the measurement endpoint). The measurement endpoint is selected based on the longitudinal extent of the dissection, with two scenarios: when the end of the dissection is above the bifurcation of the abdominal aorta, the end of the dissection is selected as the measurement endpoint; when the dissection continuously extends to or below the iliac artery, the bifurcation of the abdominal aorta is selected as the endpoint. The three-dimensional coordinates of each point are exported sequentially as a text document.

[0025] This measurement method is based on CT angiography images of patients diagnosed with aortic dissection. The DICOM format images are imported into the free and open-source software 3D Slicer (3D Slicer.5.0.3 Fedorov A, Beichel R, Kalpathy-Cramer J, et al. 3D Slicer as an Image Computing Platform for the Quantitative Imaging Network. Magnetic Resonance Imaging. 2012 Nov; 30(9):1323-41. https: / / www.slicer.org / , abbreviated as 3D Slicer).

[0026] Import the stored text document into the software R (R Core Team (2022). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https: / / www.r-project.org / , abbreviated as R).

[0027] The second step is to calculate the degree of distortion of the false cavity: Import the text document into software R, taking the first measurement plane as an example, such as... Figure 2 As shown, based on the knowledge of analytic geometry and polar coordinates, A1(x) in this plane A1 ,yA1 ,z A1 B1(x) B1 ,y B1 ,z B1 C1(x) C1 ,y C1 ,z C1 Three points can define a circle, denoted as O1. The coordinates (x, y) of the center O1 can be obtained using formulas 1.1-1.4. O1 ,y O1 ,z O1 and radius r O1 .

[0028]

[0029]

[0030] z O1 =z A1 ; (Formula 1.3)

[0031]

[0032] in:

[0033] With the center O1 coordinate (x O1 ,y O1 ,z O1 Let point A1, B1, and C1 be the pole, and the horizontal direction to the right (OX) be the polar axis. The counterclockwise direction is defined as the positive direction. Establish a planar polar coordinate system within this measurement plane. Using formulas 2.1-2.2, convert the coordinates of A1, B1, and C1 to polar coordinates. Then, the angle ∠θ between points A1, B1, and C1 and the polar axis can be determined. A1 , ∠θ B2 and ∠θ C3 .

[0034]

[0035] Where i represents A1, B1, and C1. (Formula 2.2)

[0036] Using ∠θ A1 , ∠θ B1 The average of ∠θ M1 The angle bisector ∠θ represents the torsion angle of the false cavity relative to the true cavity in this plane. The angle bisector measure ∠θ can be obtained using formulas 2.1 and 2.3. M1 and coordinates M1(x M1 ,y M1 ,z M1 ).

[0037] θM1 =0.5×(θ) A1 +θ B1 ); (Formula 2.3)

[0038] At this point, the coordinates and angles within the first measurement plane are calculated. This method is then used to calculate all measurement planes sequentially and record the results. Figure 3 , Figure 4 As shown. Substituting into the following formulas, the various indices of the pseudo-cavity distortion can be obtained (i represents the measurement plane at the end):

[0039] (1) False cavity distortion index: The ratio of the distance traveled by the midpoint M of the false cavity arc AB within the measurement range to the center O of the arc, representing the percentage of the false cavity offset relative to the true cavity within the interlayer tear range. A result of zero indicates that the false cavity has not been distorted relative to the true cavity, and can be calculated by formulas 3.1-3.3. Distance M Distance represents the distance traveled by point M. O Indicates the distance traveled by point O, such as Figure 5 As shown.

[0040]

[0041]

[0042] False cavity distortion index = (Distance) M -Distance O ) / Distance O ×100%; (Formula 3.3)

[0043] (2) Percentage of false lumen tear: This represents the percentage of the false lumen tear angle relative to the aortic circumference at each measurement plane, and can be calculated using formula 3.4, such as... Figure 6 As shown.

[0044]

[0045] (3) Cumulative distortion of the false cavity: with the coordinates of the midpoint M of AB as z M With the horizontal axis as the axis, the plane is twisted by the angle ∠θ. M Plot a line graph with the vertical axis as the ordinate. The area enclosed by the line and the horizontal axis represents the cumulative distortion of the false cavity. Figure 7 As shown.

[0046] (4) Average rate of change of pseudo-cavity torsion: adjacent torsion angles ∠θ within the measurement range M The average rate of change of the sum of changes can be calculated using formula 3.5.

[0047]

[0048] (5) Standard deviation of false cavity torsion angle: represents the degree of dispersion of a set of torsion angles, which can be calculated by formula 3.6.

[0049]

[0050] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A novel method for determining the degree of torsion in aortic dissection, characterized in that, Includes the following steps: On CT angiography images, a coordinate system is established to determine the location of the false lumen and the range of the dissection tear length. Three-dimensional coordinates are measured at the dissection tear in axial sequence: two intersection points A and B between the false lumen and the aortic wall, and point C on the curve of the aortic wall where the false lumen is located. Subsequently, the coordinates of three points in each axial sequence image within the dissection tear range are measured. Based on the coordinates of the two intersection points A and B between the false lumen and the aortic wall, and the coordinates of point C on the aortic wall curve, the three-dimensional coordinates of the center O are determined. A polar coordinate system is established with the center O as the pole for all measurement planes, and the polar angle ∠θ between points A, B, and C is obtained. A ,∠θ B and ∠θ C Using ∠θ A ,∠θ B The average ∠θ is the torsion angle of the planar pseudo-cavity, and the coordinates of the intersection point M of angle θ and circle O are calculated based on all measured plane points A, B, O, M, and angle ∠θ. A ,∠θ B ,∠θ C The degree of distortion of the false cavity is calculated by ∠θ. The indicators of false cavity distortion include false cavity distortion index, false cavity tear percentage, false cavity cumulative distortion degree, false cavity distortion average change rate, and false cavity distortion angle standard deviation; The false cavity torsion index is the ratio of the distance traveled by the midpoint M of the false cavity arc AB within the measurement range to the center O, representing the percentage of the false cavity offset relative to the true cavity within the interlayer tear range; The cumulative distortion degree of the pseudo-cavity: (based on the coordinates z of the midpoint M of AB) M Using the horizontal axis as the x-axis, and the plane of false cavity twist angle ∠θ M Plot a line graph with the vertical axis as the ordinate, and the area enclosed by the line and the horizontal axis represents the cumulative distortion of the false cavity.

2. The novel method for determining the degree of torsion in aortic dissection according to claim 1, characterized in that, Using analytic geometry and polar coordinates, calculate the three-dimensional coordinates of the center O of the circle by measuring three points A, B, and C on the plane.

3. The novel method for determining the degree of torsion in aortic dissection according to claim 1, characterized in that, When establishing a polar coordinate system, the horizontal direction to the right is taken as the polar axis, and the counterclockwise direction is taken as the positive direction.

4. The novel method for determining the degree of torsion in aortic dissection according to claim 1, characterized in that, The percentage of false lumen tear represents the percentage of the aortic circumference at each measurement plane.

5. The novel method for determining the degree of torsion in aortic dissection according to claim 1, characterized in that, The average rate of change of the pseudo-cavity distortion is the rate of change of adjacent distortion angles ∠θ within the measurement range. M The average rate of change of the sum of changes.

6. The novel method for determining the degree of torsion in aortic dissection according to claim 1, characterized in that, The standard deviation of the pseudo-cavity torsion angle represents the degree of dispersion of a set of torsion angles.

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