CN111227930A

CN111227930A - 3D model construction and preparation method for mitral regurgitation and calcified stenosis

Info

Publication number: CN111227930A
Application number: CN202010018012.2A
Authority: CN
Inventors: 李亚杰; 曾博文; 马克军
Original assignee: Xi'an Mark Medical Technology Co Ltd
Current assignee: Xi'an Mark Medical Technology Co Ltd
Priority date: 2020-01-08
Filing date: 2020-01-08
Publication date: 2020-06-05
Anticipated expiration: 2040-01-08
Also published as: CN111227930B

Abstract

The invention belongs to the field of 3D printing, and discloses a 3D model construction and preparation method for mitral regurgitation and calcified stenosis. In the model construction method, firstly, left cardiac structure radiography data of a patient with mitral regurgitation and calcified stenosis is collected and preprocessed to obtain cardiac CT data; then establishing a calcified tissue model and a blood model according to gray values corresponding to different tissues in the cardiac CT data; then, reconstructing and deleting redundant artifact blood structures in the inner cavity model aiming at the leaflet chordae tendineae and papillary muscles to obtain the inner cavity model; and finally, cutting the inner cavity model, and performing Boolean operation on the cut inner cavity model and the calcified tissue model to obtain the 3D model of the mitral valve calcified stenosis and the mitral valve regurgitation disease. The method well solves the problems of limitations of the traditional image evaluation on the mitral valve structure and the structure under the mitral valve in the prior art.

Description

3D model construction and preparation method for mitral regurgitation and calcified stenosis

Technical Field

The invention belongs to the field of 3D printing, and particularly relates to a 3D model construction and preparation method for mitral regurgitation and calcified stenosis.

Background

Mitral valve disease is the most common valvular disease that endangers the health of cardiovascular disease in people. Most Mitral Stenosis (MS) is a sequela of rheumatic fever, with few congenital stenosis or senile Mitral annulus or subcyclic calcification. Mitral Insufficiency (MI) is mainly caused by valve degeneration, rheumatic fever, structural damage under Mitral valve after myocardial infarction of coronary heart disease, and the like, and often causes atrial fibrillation and cardiac insufficiency. According to recent epidemiological data in developed western countries such as the united states, the leading type of valvular disease in the elderly over 65 years of age is mitral regurgitation. Research shows that the long-term effect of surgery on mitral valve stenosis is superior to drug therapy, however, some patients with mitral stenosis caused by rheumatic fever are younger in age, and the life quality is obviously affected by early replacement of the valve; meanwhile, for the high-risk patients with surgical operation of advanced age combined with multi-system diseases, the surgical risk is high, the survival benefit is less, European data show that the surgical operation success rate of the patients is only 50%, and the surgical operation success rate of the patients with severe functional reflux is as low as 16%. Minimally invasive treatment of the mitral valve is therefore always the center of gravity explored by clinicians.

In the past 5 years, the mitral valve interventional shaping and replacement devices are diversified worldwide, and the successful messages of clinical trials are frequently sent. However, to date, the spread and popularity of this technique has remained quite limited, not only with regard to the specificity of mitral valve architecture, but also with regard to the difficulty of preoperative screening and assessment of patients. Currently, experts agree to recommend transcatheter mitral valvuloplasty and replacement to be performed preoperatively, mainly by transesophageal ultrasound, with very limited accuracy. Considering that the mitral valve is a spatial three-dimensional structure, the lesion is modal-diverse, has a complex subvalvular structure and is dynamically changed in the cardiac cycle, the esophageal ultrasound and CT plane analysis have great limitation, the controllability and the intuitiveness are poor, and the Zener risk and the problem in the actual operation are often difficult to find. Therefore, a new evaluation method capable of providing a spatial stereo model for observation and simulation is urgently needed in clinic.

The intersection of 3D printing technology with medicine is gradually highlighting the advantages of this technology. Compared with the traditional imaging examination, the 3D printing technology can display rich information of the mitral valve structure, and is particularly important for clinicians. Due to the physical properties of the material and the special requirements of the mitral valve structure, new requirements are placed on the transparency, surface finish, colorful display and soft and hard combination of the model.

Disclosure of Invention

The invention aims to provide a 3D model construction and preparation method for mitral regurgitation and calcified stenosis, which are used for solving the problems of structural limitations and the like of a mitral valve and an under-valve structure in the traditional image evaluation in the prior art.

In order to realize the task, the invention adopts the following technical scheme:

A3D model construction aiming at mitral regurgitation and calcified stenosis comprises the following steps:

step 1: acquiring left heart structure radiography data of a patient with mitral regurgitation and calcified stenosis, wherein the left heart structure radiography data comprises ascending aorta angiography data, aorta root angiography data, left atrium angiography data, left ventricle angiography data, coronary angiography data, left auricle angiography data, mitral valve leaflet angiography data, chordae tendinae angiography data and papillary muscle angiography data, and preprocessing the left heart structure angiography data to obtain heart CT data;

step 2: establishing a calcified tissue model and a blood model according to gray values corresponding to different tissues in cardiac CT data, wherein the blood model comprises an aorta root inner cavity blood model, an ascending aorta inner cavity blood model, a coronary artery inner cavity blood model, a left ventricle inner cavity blood model, a left atrium inner cavity blood model and a left atrial appendage inner cavity blood model;

and step 3: acquiring left intracardiac structure boundaries, mitral valve leaflet boundaries, chordae tendinae boundaries and papillary muscle boundaries wrapped in a blood model, wherein the left intracardiac structure boundaries comprise an aorta root, an ascending aorta, a coronary artery, a left ventricle, a left atrium and a left atrial appendage, comparing the acquired left intracardiac structure boundaries, mitral valve leaflet boundaries, chordae tendinae boundaries and papillary muscle boundaries with actual mitral valve leaflet boundaries, chordae tendinae boundaries and papillary muscle boundaries in cardiac CT data, correcting the boundaries, and deleting the blood model to obtain an inner cavity model;

and 4, step 4: and (3) cutting the inner cavity model, reserving part of the left atrium, the left ventricle, the left auricle opening, the aortic root, the coronary artery opening, the mitral valve leaflets, the chordae tendinae and the papillary muscles in the inner cavity model, and then performing Boolean operation on the cut inner cavity model and the calcified tissue model obtained in the step (2) to obtain a 3D model of the mitral valve calcified stenosis and the mitral valve regurgitation disease.

Further, the pretreatment in step1 comprises the following substeps:

step a: selecting a group of aortic angiography data in the optimal leaflet observation state, and establishing an annulus plane according to the group of data, wherein the optimal leaflet observation state refers to the state of maximal left ventricular diastole or minimal left ventricular systole;

step b: and observing the left heart structure contrast data from top to bottom along the annulus plane, and adjusting the gray value of the left heart structure contrast data until mitral valve leaflets, chordae tendineae, papillary muscle structures, calcification distribution conditions, mitral valve annulus morphology and a left ventricle chamber are clearly seen to obtain heart CT data.

Further, the gray value range of the left heart structure contrast data in the step b is as follows: the minimum value is 250-400, and the maximum value is 3071.

A method for preparing a 3D model aiming at mitral valve diseases comprises the following steps:

step 1: obtaining a 3D model of mitral valve disease by using the 3D model construction method for mitral regurgitation and calcified stenosis as claimed in any one of claims 1-3;

step 2: introducing the 3D model into OBJET slicing software for printing, then placing the printed 3D model into an alkaline solution for vibration cleaning, taking out the model from the solution after cleaning, and washing surface residues;

and step 3: putting the 3D model obtained in the step2 into a drying box, keeping a blowing mode for drying, taking out the drying model, and polishing the surface by using a sand blasting machine;

and 4, step 4: and (5) carrying out coating treatment on the surface of the model after grinding and polishing to finish the preparation of the model.

Further, in step2, the alkaline solution is a sodium hydroxide solution with a concentration of two percent and a sodium metasilicate solution with a concentration of one percent

Further, in the step2, the frequency of the oscillation cleaning is 25KHz, and the time of the oscillation cleaning is 30 minutes.

Further, in the step3, the temperature of the drying box is set to be 75 ℃, and the drying time is 150 minutes.

Furthermore, in the step3, the sand blasting machine firstly polishes impurities on the surface of the model by using 50-mesh gravel, and then polishes the surface of the model by using 200-mesh gravel.

Further, when the coating treatment is performed in the step4, the following steps are adopted:

first coating operation was performed with 195T potting silica gel, then with a coating according to 10: 1.2 mixing the silica gel and the curing agent in proportion to carry out secondary coating operation, and finally sealing the surface of the model with the curing agent.

Compared with the prior art, the invention has the following technical characteristics:

the mitral valve model obtained by the 3D printing technology can be better evaluated, and the mitral valve model has the following advantages under the guidance of mitral regurgitation:

(1) the mitral valve replacement 3D printing model can be subjected to preoperative comprehensive assessment and patient screening, so that operation strategy formulation, valve model selection and implantation depth determination are performed, meanwhile, the 3D printing model can help vertically select a proper apical puncture part, important structures such as coronary arteries on the surface of cardiac muscle, chordae tendineae in ventricles, papillary muscles and the like are avoided, and important anatomical structures are prevented from being influenced by the in-and-out of guide wires and interventional valves in the operation.

(2) Aiming at the mitral valve repair, the printed three-dimensional mitral valve model can stereoscopically see the lesion area of the mitral valve leaflets and the structures of the left ventricle and the left atrium. Thereby, the doctor can analyze the selection of the surgical plan and select the clamping position in vitro.

The following advantages are provided in guiding calcified stenosis of the mitral valve:

(3) printing the model and showing left auricle and left ventricle structure, the simulation avoids instructing the art person to avoid haring the left auricle before the art, to the narrow patient of valve opening, can help the art person to find the angle and the direction of suitable propelling movement sacculus, reduces the operation among the actual operation consuming time and the ray is ingested.

Drawings

FIG. 1 is a schematic diagram of a 3D heart model obtained by a conventional modeling method;

FIG. 2 is a heart chamber dissection model obtained by conventional modeling methods;

FIG. 3 is a schematic diagram of a blood model of the heart system obtained by the present invention;

FIG. 4 is a schematic view of a reconstructed 3D left heart model of the present invention;

FIG. 5 illustrates the mitral valve leaflets reconstructed by the present invention;

fig. 6 is a final model of a mitral valve leaflet in an embodiment of the invention;

fig. 7 is a papillary muscle model of chordae tendineae in an embodiment of the invention;

fig. 8 is a lumen model in an embodiment of the invention.

Detailed Description

The design process of three-dimensional printing is as follows: the method is characterized in that firstly, modeling is carried out through computer modeling software, and then the built three-dimensional model is divided into sections, namely slices, layer by layer, so as to guide a printer to print layer by layer. The invention therefore also includes a modeling process and a slice printing process.

The embodiment discloses a 3D model construction method for mitral regurgitation and calcified stenosis, which includes the following steps:

step 1: acquiring left heart structure radiography data of a patient with mitral regurgitation and calcified stenosis, wherein the left heart structure radiography data comprises ascending aorta angiography data, aorta root angiography data, left atrium angiography data, left ventricle angiography data, coronary artery angiography data, left auricle angiography data, pulmonary vein angiography data, mitral valve leaflet angiography data, chordae tendineae angiography data and papillary muscle angiography data, and preprocessing the left heart structure radiography data to obtain heart CT data;

the contrast data is selected according to the condition of a calcification part of a patient;

and step 3: acquiring left intracardiac structure boundaries, mitral valve leaflet boundaries, chordae tendinae boundaries and papillary muscle boundaries wrapped in a blood model, wherein the left intracardiac structure boundaries comprise an aorta root, an ascending aorta, a coronary artery, a left ventricle, a left atrium and a left atrial appendage, comparing the left intracardiac structure boundaries, the mitral valve leaflet boundaries, the chordae tendinae boundaries and the papillary muscle boundaries with actual mitral valve leaflet boundaries, chordae tendinae boundaries and papillary muscle boundaries in cardiac CT data, correcting the boundaries, and deleting the blood model to obtain an inner cavity model;

Wherein, different tissues show different colors on a computer because of different absorption of X-rays by different tissues, and the boundaries of the tissues are divided according to the difference of the colors.

The process of establishing the calcified tissue model comprises the following steps: screening calcified tissues according to corresponding gray values of the calcified tissues, segmenting tissues connected with calcification, and establishing a calcified tissue 3D model, wherein the calcified tissue 3D model can truly reflect the calcification degree to the maximum extent;

preferably, the gray scale value range of the calcified tissue is: the minimum value interval is 530 and 630, and the maximum value is 3071.

Preferably, the range of gray values for the blood structure is: the minimum value interval is 164-261, and the maximum value is 3071.

In the scheme, the boolean operation is used for fusing the cut inner cavity model and the calcified tissue model to obtain a complete 3D model.

Specifically, the basis for clipping in step4 is to determine whether the reconstructed leaflet boundary on the model is close to the CT upper boundary, and if not, modify the model, cut off the pulmonary veins, left atrial appendage, partial left atrium, partial left ventricle, partial ascending aorta, and redundant coronary arteries contained in the entire left heart system, and create a complete lumen model.

Specifically, the pretreatment in step1 includes the following substeps:

step a: selecting a group of left heart structure radiography data in the optimal leaflet observation state, and establishing an annulus plane according to the group of data, wherein the optimal leaflet observation state is the state with the maximum left ventricular diastole or the minimum left ventricular systole, namely the data in the optimal systole and diastole states; and selecting according to the compared multiple groups of CT data. The mitral valve annulus is a complex spatial structure because of its complex structure, and is also in a dynamic state with the cardiac cycle, so that it is necessary to reconstruct the diastolic and systolic phases as a surgical reference. The CT data for a patient includes at least one cardiac cycle divided into different groups, with one group selected from the different groups.

Preferably, the minimum value of the gray value range of the left heart structure contrast data is 250-400, and the maximum value is 3071;

specifically, in the step4, an annulus plane is adopted to cut off redundant parts in the complete inner cavity model, part of a left ventricle, a left atrium, an aortic root, a left auricle opening, a coronary artery opening, mitral valve leaflets, chordae tendineae and papillary muscles are reserved, the model is redrawn into grids and the surface of the model is smooth, the model is hollowed out to form a hollow structure, a repair model is checked, then Boolean operation is carried out on the cut inner cavity model and the calcified tissue model obtained in the step2 to obtain a 3D model aiming at mitral valve regurgitation and calcified stenosis, whether the obtained 3D model meets requirements of an anatomical structure or not is checked, and the contour is edited to be more real.

Example 1:

the embodiment discloses a 3D model construction method for mitral valve disease, which is implemented in mics software by the following steps:

(1) the medical imaging equipment is used for collecting data of mitral valve diseases (mitral valve calcified stenosis, left angiography of patients with mitral regurgitation, mainly collecting the aortic root, part of ascending aorta, coronary artery, left atrium and left ventricle of the patients, and generating a CT (DICOM) file containing systole and diastole.

(2) Importing DICOM files into the Mimics software, and generating the mcs files for storage

(3) Data partitioning:

step1, observing different tissues, calcified structures and boundary conditions, valve leaflet shapes and calcification degrees according to different chromatograms shown in different tissues in Pseudo colors commands;

step2, selecting the phase data with the maximum or minimum left heart in the CT image playback, and adjusting the pixel gray value of the data to completely and clearly see the aorta, calcification and left heart structure;

step3, establishing an annulus plane in a View (View), and clearly seeing the mitral valve leaflets and calcification distribution from top to bottom on a transverse plane;

step4, a Mask is newly built to reconstruct the tissue of the calcified part by previewing the three-dimensional model, the calcification degree can be reflected to the maximum extent, the tissue connected with the calcification is separately segmented and reconstructed by using region growing (Regiongrow),

step5, newly building a second Mask to make the Mask cover the ascending aorta lumen blood, the aorta root lumen blood and the left ventricle chamber blood;

step6, removing redundant heart tissues by a Split mask to reconstruct an internal blood model of the aorta, the left ventricle, the left atrium, the left auricle and the opening of the coronary artery;

step7, checking the integrity of the valve leaflets by a Clipping three-dimensional model, and then manually editing and deleting the structures of the mitral valve leaflets, chordae tendineae and papillary muscles contained in the internal blood to build an integral inner cavity model;

(4) importing an STL file of the output three-dimensional model into Geomagic Studio reverse software, cutting off redundant parts by using an annulus plane, reserving the root of an aorta, the opening of a coronary artery, the left ventricle, the left atrium and the opening of the left auricle, redrawing a grid on the model and smoothing the surface of the model; hollowing out the model in Magics to form a hollow structure, checking and repairing the model, cutting the end face and calcified tissues (calcifications) in Geomagic Studio again, performing Boolean operation, and storing the file;

(5) the complete three-dimensional model is input into the mcs file to make the model outline visible, check if it meets the requirements of the anatomical structure, if the editable outline is more realistic.

Example 2:

in this embodiment, the printing selection software is OBJET slicing software, and slicing software such as FDM curr, slamatrialisse magics, SLM QuantAM, and the like can also be selected.

The embodiment discloses a method for preparing a 3D model for mitral regurgitation and calcified stenosis, which includes the following steps based on embodiment 1:

step 1: obtaining a 3D model aiming at mitral regurgitation and calcified stenosis by adopting any 3D model construction method aiming at mitral regurgitation and calcified stenosis, and exporting the model into an STL format file;

step 2: the 3D model is guided into OBJET slicing software for printing, the height of the model is as low as possible in the slicing process, the printing time is reduced, after a tool is used for removing a large support on the surface of the model, the 3D model after printing is placed into alkaline solution for vibration cleaning, after the cleaning is finished, the model is taken out from the solution and the surface residue is washed, and a water gun tool is used for washing the support material and the alkaline solution which are remained on the surface;

Specifically, the step2 of placing the printed 3D model into an alkaline solution to shake and clean refers to immersing the model into a solution containing two percent of sodium hydroxide and one percent of sodium metasilicate, using an ultrasonic cleaning machine to hold the solution and the model, and after the model is immersed into the solution, using a 25KHz frequency to shake and clean for 30 minutes. If the mass of the model exceeds 300g, the oscillation time is properly prolonged, the total oscillation time of each oscillation is not more than 40 minutes, and the long-time swelling deformation of the model is avoided.

Specifically, the step3 of placing the 3D model obtained in the step2 into a drying box and keeping the model in a blowing mode for drying refers to that the model taken out is placed into a special industrial drying box and dried at the temperature of 75 ℃ for 150 minutes, the drying time of the model with the mass larger than 300g can be properly increased, the excess part is increased by 10 minutes every 50g, but the total drying time is not more than 180 minutes once, so that the long-time heating deformation of the model is avoided.

Specifically, the step3 of polishing the surface of the model by using a sand blasting machine refers to polishing impurities on the surface of the model by using 50-mesh gravel, and then polishing the surface of the model by using 200-mesh gravel.

Specifically, when the coating treatment is performed in the step4, the following steps are adopted:

Preferably, the model is coated with 195T casting glue, polyurethane casting glue, flexible UV varnish, aqueous polyurethane coating glue, and the like.

Different according to the requirement of model, use different coating materials can obtain corresponding different effects, use 195T embedment glue and polyurethane casting glue can increase the permeability of model, will allocate good 195T embedment glue and polyurethane casting glue according to 2: 1, the 195T pouring sealant can increase the viscosity of the liquid, and the polyurethane pouring sealant can increase the adhesive force between the liquid and the model after the liquid is solidified.

The model using the water-based polyurethane coating adhesive coating has lower transparency than the model using the pouring adhesive coating, but has stronger adhesive force than the pouring adhesive coating, and can ensure that the coating material does not fall off due to rubbing and friction when an instrument is used for simulation.

The material using the flexible UV gloss oil coating has transparency and adhesive force between those of the potting adhesive and the coating adhesive, and the coating is the thinnest and the curing speed is the fastest in all coating materials.

Specifically, the specific types of the various materials are as follows:

pouring sealant: osbang 195T transparent heat-conducting organic silicon pouring sealant.

Polyurethane pouring sealant: osbang 130pu transparent polyurethane pouring sealant.

UV flexible gloss oil: preferably 6510-46 UV gloss oil pressed by flexible film.

Aqueous polyurethane coating adhesive: a novel constant-weather material, namely, a non-ionic waterborne polyurethane resin HT-201 soft advection waterborne textile coating adhesive.

Comparative example 1:

(1) importing the DICOM file into the mimics software, and selecting images in a systolic period or a diastolic period;

(2) manually adjusting the CT gray value to see the outline of the left heart system;

(3) and a Mask is newly built, a threshold value is manually adjusted, a certain pixel gray value range including the inner wall and the outer wall of the aorta, the left atrium, the left ventricle, the left auricle and the left and right coronary arteries is selected, the aortic sinus and the aortic root form a lumen structure, and a region growing command is used for independent selection.

(4) Calculating a three-dimensional model with thick vessel wall, selecting a high-brightness calcified leaflet by using dynamic region growth, and checking whether the leaflet is completely reconstructed or not by using a Clipping model and whether the leaflet meets the requirement of surgical evaluation or not;

(5) rebuilding a model of valve leaflets, chordae tendineae and papillary muscles according to the Edit pixel gray value required by the operation evaluation, and removing redundant tissues or adding a valve tissue mask;

(6) the Smoothing model enables the inner surface and the outer surface of the model to be smooth, and as the densities of a blood vessel wall and an external heart tissue are close under the influence of equipment, the grey values in the mimics are close and difficult to separate, the three-dimensional model is required to generate an STL file and is led into the Geomagic Studio for reverse modeling;

(7) in the Geomagic Studio, a polygon command is used to delete triangular patches at redundant structures, a mesh is redrawn and a model is relaxed, three points with uniform distribution (valve ring plane) at the mitral valve are respectively selected by using three point plane section commands, and redundant tissues are cut out.

(8) If the mitral valve is calcified, introducing the calcification into a Geomagic Studio to perform Boolean operation with the aortic valve, and storing the model as an STL file;

(9) opening the STL model in Magics, clicking the repair model, if the model diagnosis has no problem, importing the model into the slice software slice and printing.

As shown in fig. 1, in comparative example 1, the inner and outer walls of the blood vessel are modeled by a simple adjustment threshold, the calcified position cannot be quickly and accurately reconstructed, the calcified position can be adhered to other soft heart tissues, and the later segmentation is complicated and difficult.

As shown in fig. 2, the conventional modeling method adopted in comparative example 1 can cover the heart with unnecessary soft tissue, the valve leaflet passage is not clear, meanwhile, the reconstructed in fig. 2 is a blood vessel lumen model, the reconstructed in fig. 4 is an internal blood form, and fig. 5 and fig. 2 have less noise, more obvious and accurate valve leaflet form and stronger purpose and have less post-processing work.

Claims

1. A3D model construction for mitral regurgitation and calcified stenosis is characterized by comprising the following steps:

2. The method for constructing a 3D model of mitral regurgitation and calcified stenosis according to claim 1 wherein the preprocessing in step1 comprises the sub-steps of:

3. The method of claim 2, wherein the gray-scale values of the left cardiac structure contrast data in step b are in the range of: the minimum value is 250-400, and the maximum value is 3071.

4. A method for preparing a 3D model aiming at mitral valve diseases is characterized by comprising the following steps:

5. The method for preparing a 3D model for mitral valve disease according to claim 4, wherein the alkaline solution in step2 is sodium hydroxide solution with a concentration of three-point five percent and sodium metasilicate solution with a concentration of two percent.

6. The method for preparing a 3D model of mitral valve disease according to claim 4, wherein the frequency of the shaking and cleaning in step2 is 27KHz, and the time of the shaking and cleaning is 45 minutes.

7. The method for preparing a 3D model of mitral valve disease according to claim 4, wherein the temperature of the drying oven is set to 75 ℃ in step3, and the drying time is 225 minutes.

8. The method of claim 4, wherein the sand blasting machine in step3 grinds the surface impurities of the model with 50 mesh grit, then finely grinds the surface of the model with 200 mesh grit, and finally polishes the surface of the model with 400 mesh grit.

9. The method for preparing a 3D model for mitral valve disease according to claim 4, wherein the coating process in step4 comprises the following steps: