CN107464275A - Human spine center line three-dimensional reconstruction method - Google Patents

Abstract

The invention discloses a kind of human spine center line three-dimensional reconstruction method.Its contour map by building human body back surface song looks, human body back center line is have found with reference to contour correlated characteristic, integer interpolation is carried out to dorsal midline and obtains each point curvature on dorsal midline, backbone torso length is tried to achieve using anatomic marker point and obtains vertebral body length expressions, finally substitute into correlation models reconstruct midspinal line three-dimensional curve, reconstruction precision is substantially increased, rebuilds excellent effect.

Description

Three-Dimensional Reconstruction Method of Human Spine Midline

technical field

The invention belongs to the technical field of image processing, and in particular relates to a method for three-dimensional reconstruction of the midline of the human spine.

Background technique

The spine is the central axis of the human body. Once scoliosis occurs, it will not only give people a deformed appearance, but also cause serious mental trauma to children. Spinal deformities that occur in the early years will also affect the development and maturity of children's heart and lungs, and some may also affect the spinal cord and nerves. The incidence of scoliosis in the population is about 1%. In many cases, it has little impact on life in the early stage. Many parents ignore it, and physical examination is not a routine item. As a result, many teenagers miss the opportunity to correct easily, causing health problems that affect the quality of life throughout their lives.

Scoliosis, also known as scoliosis, is caused by the deviation of the spine segment from the centerline of the back on the coronal plane of the human body and bending to the side. Usually accompanied by spinal rotation and sagittal kyphosis or lordosis and other symptoms. There are many factors that cause scoliosis, among which the undetermined cause is called idiopathic scoliosis. Liu Shangli and others found that idiopathic patients accounted for 96.9% of scoliosis in the general survey of scoliosis. The measurement standards for scoliosis are not exactly the same. Some scholars judge patients with Cobb angles greater than 5° measured in the coronal plane as scoliosis, and generally judge patients with Cobb angles greater than 10° as scoliosis .

Liu Shangli and others conducted a scoliosis survey on 87,546 adolescents in Guangdong in 2002, and the prevalence rate was 0.7500. In 2009, Zhou Huiqing and others conducted a general survey of 32,280 primary and middle school students with scoliosis in Huian County, Fujian Province, and the prevalence rate was 0.73%. In addition to causing back asymmetry and body shape defects, scoliosis can lead to secondary thoracic deformity in severe cases, which in turn can cause visceral dysfunction, especially causing serious physical and mental harm to adolescents in the growth and development stage. From the results of the above-mentioned census, it can be known that scoliosis has a certain prevalence rate among adolescents. If it cannot be detected and treated as early as possible, it will cause harm to the physical and mental development of many adolescents.

The X-rays used for traditional scoliosis detection are highly radioactive, which is not good for the growth and development of adolescents. The newly developed harmless detection system abroad is expensive, and it is difficult for ordinary patients to use it in ordinary hospitals, because there are only a few in Beijing, and there is no West China Hospital in Southwest China, let alone other hospitals. Therefore, it is of great social value and significance to study simple and easy scoliosis inspection methods.

There are many methods for examining scoliosis, which can be roughly divided into two categories: physical measurement methods and image measurement methods. Physical measurement methods refer to methods that have direct contact with the back of the human body when measuring scoliosis, mainly including the Adams forward bending test, the application of scoliosis rulers to measure the rotation angle of the trunk, and the measurement of rib protuberances; image measurement The method refers to the method that does not directly contact the back of the human body during the inspection, mainly including Moire image measurement method, X-ray film measurement method, structured light measurement method, laser scanner measurement method, etc. In the census, in addition to observing whether the shoulders are of equal height, the Adams forward bending test is used, and suspicious patients are further checked by X-ray film measurement. Patias et al. explained and compared the measurement parameters of Adams forward bending test, optical measurement technology and other testing methods. Xiong Long and other homemade scoliosis measuring instruments are used for scoliosis screening.

At present, image processing technology has been introduced into the medical field as an effective visual detection tool, among which X-ray films and Moiré images are relatively used in the detection of scoliosis. Due to the potential hazards of X-ray radiation to human health, X-ray film measurement is generally not used for censuses, but for further accurate inspection of cases screened out by the census. In addition, Qiu Yong pointed out that the X-ray measurement method only focuses on the Cobb angle on the coronal plane, but the detection of scoliosis caused by spinal rotation is not obvious. Moiré images are images obtained based on periodic gratings, which are sensitive to small rotations and deformations of objects. Moiré images are also called moiré images in medicine. The use of Moiré images to examine scoliosis began earlier. In 1979, Willner established the relationship between the asymmetry of Moiré images and the Cobb angle to judge scoliosis. The author also pointed out that in concave parts Moore The stripes are severely deformed, but appear clear in the convex parts. In 1983, Kamal gave a formula for calculating the Cobb angle by using a pair of asymmetric point information on the Moiré fringe in the Moiré image. In 2008, Guo Wei et al. introduced the role of moiré patterns in spine health screening and orthopedic surgery. From 2001 to 2008, Kim et al. did a series of work on judging scoliosis by using the Moiré image symmetry features of the human back. In 2010, Gaal et al. used the formula proposed by Kamal to select 7 pairs of asymmetric points in the Moiré image for the same patient, calculate 7 Cobb angles, and take the statistical average as the final Cobb angle to judge scoliosis. .

The first two image measurement methods extract feature information from two-dimensional images to judge scoliosis. In order to improve the accuracy of judgment, people propose to extract features from three-dimensional information of the back to judge scoliosis. Berryman et al. used rectangular structured light to reconstruct the human back, and extracted its three-dimensional symmetry features to judge scoliosis. Ramirez et al. used Minolta VIVID 700 laser scanner to obtain accurate three-dimensional data of the back, and judged scoliosis according to its symmetry characteristics and support vector machine method, with a discrimination rate of 85%. Chong et al proposed an image measurement technique for outdoor scoliosis.

Because the physical measurement method is based on manual detection, manual detection becomes quite cumbersome and inefficient when conducting a census on a large number of people, and doctors will cause misjudgments and misjudgments due to fatigue. In order to reduce manual participation, improve efficiency, and avoid errors caused by physicians' subjective factors, the image measurement method is a better method for the detection of scoliosis.

Contents of the invention

The purpose of the present invention is: in order to solve the above problems in the prior art, the present invention proposes a method for three-dimensional reconstruction of the midline of the human spine.

The technical solution of the present invention is: a method for three-dimensional reconstruction of the midline of the human spine, comprising the following steps:

A. Obtain the three-dimensional image of the back of the human body, perform contour processing on the three-dimensional image of the back of the human body, and obtain the contour map of the human back; The three-dimensional coordinates of each point on the protruding line;

B, calculating the included angle between the normal line of each point on the spinous process line and the horizontal direction in step A, and obtaining the surface curvature of each point on the spinous process line;

C. Calculate the three-dimensional coordinates of the anatomical landmarks on the back of the human body;

D. Establish the correlation model between the back of the human body and the midline of the spine. According to the three-dimensional coordinates of each point on the spinous process line in step A, the surface curvature of each point on the spinous process line in step B, and the three-dimensional coordinates marked anatomically in step C 3D reconstruction of the midline of the human spine.

Further, the calculation of the normal of each point on the spinous process in the step B also includes vector superposition of the normal of a point on the spinous process and the normal of eight adjacent points of the point, and then vector superimposed The normal value acts as the normal value for the point.

Further, the anatomical landmarks on the back of the human body in the step C are specifically the lower carina of the human back and the posterior superior iliac spines on both sides; the carinas are used as the starting point for measuring the spine.

Further, the correlation model between the back of the human body and the midline of the spine in the step D is expressed as:

x _m = x _s + L·sinθ

y _m =y _s

z _m = z _s + L·cosθ

Among them, (x _m , y _m , z _m ) are point coordinates on the midline of the spine, (x _s , y _s , z _s ) are point coordinates on the symmetrical midline of the back of the human body, L is the length of the main body of the spine, and θ is the side of the spine bend angle.

Further, the calculation formula of the length of the main body of the spine in the correlation model between the back of the human body and the midline of the spine is specifically:

L(y _s )＝0.132·T-0.035·y _s

where T is the length of the spine.

The beneficial effects of the present invention are: the present invention finds the midline of the back of the human body by constructing the contour map of the surface curvature of the back of the human body and combining the relevant features of the contour line, performs integer interpolation on the midline of the back to obtain the curvature of each point on the midline of the back, and utilizes anatomical The length of the trunk of the spine is obtained from the landmark points of the spine and the expression of the length of the main body of the spine is obtained. Finally, the three-dimensional curve of the midline of the spine is reconstructed by substituting it into the correlation model, which greatly improves the reconstruction accuracy and the reconstruction effect is excellent.

Description of drawings

Fig. 1 is a schematic flowchart of the method for three-dimensional reconstruction of the midline of the human spine according to the present invention.

Fig. 2 is a schematic diagram of contour lines of the back of a human body in an embodiment of the present invention.

Fig. 3 is a schematic diagram of spinous process lines on the back of a human body in an embodiment of the present invention.

Fig. 4 is a schematic diagram of the curvature of symmetrical points on the back surface of the human body in an embodiment of the present invention.

Fig. 5 is a schematic diagram of anatomical landmarks on the back of a human body in an embodiment of the present invention.

Fig. 6 is a schematic diagram of the midline point of the human back spine in an embodiment of the present invention.

Fig. 7 is a three-dimensional reconstructed front view of the midline of the spine of the back of the human body in an embodiment of the present invention.

Fig. 8 is a side view of the three-dimensional reconstruction of the midline of the back spine of the human body in the embodiment of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in FIG. 1 , it is a schematic flowchart of the method for three-dimensional reconstruction of the midline of the human spine according to the present invention. A method for three-dimensional reconstruction of the midline of the human spine, comprising the following steps:

A. Obtain the three-dimensional image of the back of the human body, perform contour processing on the three-dimensional image of the back of the human body, and obtain the contour map of the human back; The three-dimensional coordinates of each point on the protruding line;

B, calculating the included angle between the normal line of each point on the spinous process line and the horizontal direction in step A, and obtaining the surface curvature of each point on the spinous process line;

C. Calculate the three-dimensional coordinates of the anatomical landmarks on the back of the human body;

D. Establish the correlation model between the back of the human body and the midline of the spine. According to the three-dimensional coordinates of each point on the spinous process line in step A, the surface curvature of each point on the spinous process line in step B, and the three-dimensional coordinates marked anatomically in step C 3D reconstruction of the midline of the human spine.

In step A, the spinous process line is the spine from the neck to the buttocks on the midline of the back of the human body, and the raised tip part that can be felt on the body surface. The present invention estimates the spinous process line according to the symmetry line of the back of the human body; the symmetry line is composed of symmetry points, and the symmetry point refers to dividing the horizontal section of the back into two halves, so that the two halves have the smallest lateral asymmetry.

The present invention performs contour processing on the three-dimensional image of the back of the human body by acquiring the three-dimensional image of the back of the human body. As shown in FIG. There will be local extreme points on the contour line of the area; according to the theory of the human back shape and the contour line, it can be known that the top of the mountain corresponds to the peak point of the human shoulder blade (the most prominent outward point on the outer edge of the acromion) in the landform. point), the shape structure similar to the saddle is formed in the middle of the two shoulder blades, the valley corresponds to the area where the spine is located (when the human body stands up straight, the area where the spine is located is concave relative to the sides of the back of the human body), the contour line of the area where the spine is located The apex or the points around it are the symmetrical points (spinous process points) of the back of the human body. Therefore, the present invention obtains the three-dimensional coordinates of each point on the spinous process line by calculating the extremum points of the contour line of the spine area of the human body back in the contour map of the human body back. FIG. 3 is a schematic diagram of the spinous process line on the back of the human body in the embodiment of the present invention.

In step B, the surface curvature of each point on the spinous process line in the present invention is expressed by measuring the angle between the surface normal and the horizontal direction (z axis); according to the grid diagram of the back of the human body, the symmetrical center line obtained can be analyzed According to the normal of the grid where the point is located, the angle between the normal of each point on the symmetrical midline and the horizontal direction is obtained according to the defined horizontal direction (that is, the direction perpendicular to the z-axis of the back of the human body). Since the obtained symmetry line of the back of the human body is a scatter diagram, after obtaining the surface curvature of each scatter point on the symmetry line, the surface curvature of the scatter points on the symmetry line is interpolated according to the smoothness of the spine change to obtain a more refined back Symmetry line surface curvature value. As shown in FIG. 4 , it is a schematic diagram of the curvature of symmetrical points on the back surface of the human body in an embodiment of the present invention.

Since there will be certain errors in the search process for each scattered point on the symmetric line of the back of the human body (there are some factors such as occlusion and noise on the back of the human body), so the present invention performs a filtering process on the scattered points on the symmetric line to filter a point on the spinous process line. The normal of the point is vector-superimposed with the normals of the eight adjacent points, and then the normal value after the vector superposition is used as the normal value of the point, so as to obtain a more accurate surface curvature of each point on the spinous process .

In step C, the anatomical landmarks of the present invention refer to the bone structure under the back of the human body, which are respectively: carina and posterior superior iliac spine on both sides. In the anatomical landmarks, the landmarks of the protruding bone are used as the origin of establishing the three-dimensional body coordinates of the spine, and also as the starting point of the spine measurement; the present invention obtains their three-dimensional coordinates by affixing corresponding landmarks on the anatomical landmarks Position, some measurements required in model building, are measured through these landmarks, such as trunk length (the vertical distance from the carina to the midpoint of the posterior superior iliac spine on both sides). As shown in FIG. 5 , it is a schematic diagram of the anatomical landmarks of the back of the human body in the embodiment of the present invention.

In step D, the present invention sets S _x = (x _s , y _s , z _s ) as the point on the symmetrical midline of the back of the human body, and M=(x _m , y _m , z _m ) as the corresponding point on the midline of the spine , to establish a correlation model between the human back and the midline of the spine, expressed as:

x _m = x _s + L·sinθ

y _m =y _s

z _m = z _s + L·cosθ

Among them, (x _m , y _m , z _m ) are point coordinates on the midline of the spine, (x _s , y _s , z _s ) are point coordinates on the symmetrical midline of the back of the human body, L is the length of the main body of the spine, and θ is the side of the spine bend angle. Here, the length L of the main body of the spine can be calculated by using the scale factor, the length of the trunk of the spine, and the longitudinal coordinates, expressed as

L(y _s )＝0.132·T-0.035·y _s

Among them, T is the length of the trunk of the spine, that is, the projected distance from the carina to the midpoint of the posterosuperior iliac bone on both sides. For a specific sample, it is equivalent to a constant.

The present invention substitutes the measured T=494.0mm into the above formula to obtain the relational expression of the symmetrical midline of the back of the human body and the midline of the spine, expressed as:

x _m ＝x _s +(65.2-0.035·y _s )·sinθ

y _m =y _s

z _m =z _s +(65.2-0.035·y _s )·cosθ

Substituting the three-dimensional coordinates of each point on the spinous process line in step A and the surface curvature of each point on the spinous process line in step B into the above formula, the three-dimensional point on the midline of the human back spine can be obtained. As shown in FIG. 6 , it is a schematic diagram of the midline point of the human back spine in the embodiment of the present invention.

Taking the coordinates of the bony point as the origin, the coordinates are translated and transformed, and the three-dimensional coordinates of the symmetrical point (spinous process point) on the back of the human body after the coordinate transformation and the corresponding surface curvature are substituted into the above formula to obtain the centerline point of the human back spine relative to the symmetrical centerline three-dimensional coordinates. As shown in FIG. 7 , it is a three-dimensional reconstructed front view of the midline of the back spine of the human body in the embodiment of the present invention. As shown in FIG. 8 , it is a side view of the three-dimensional reconstruction of the midline of the back spine of the human body in the embodiment of the present invention.

Those skilled in the art will appreciate that the embodiments described here are to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations are still within the protection scope of the present invention.

Claims (5)

1. A method for three-dimensional reconstruction of the midline of the human spine, comprising the following steps: A. Obtain the three-dimensional image of the back of the human body, perform contour processing on the three-dimensional image of the back of the human body, and obtain the contour map of the human back; The three-dimensional coordinates of each point on the protruding line; B, calculating the included angle between the normal line of each point on the spinous process line and the horizontal direction in step A, and obtaining the surface curvature of each point on the spinous process line; C. Calculate the three-dimensional coordinates of the anatomical landmarks on the back of the human body; D. Establish the correlation model between the back of the human body and the midline of the spine. According to the three-dimensional coordinates of each point on the spinous process line in step A, the surface curvature of each point on the spinous process line in step B, and the three-dimensional coordinates marked anatomically in step C 3D reconstruction of the midline of the human spine. 2. The method for three-dimensional reconstruction of the midline of human spine as claimed in claim 1, wherein calculating the normal of each point on the spinous process in the step B also includes combining the normal of a point on the spinous process with this point The normals of the eight adjacent points are vector-superimposed, and then the normal value after the vector superposition is used as the normal value of the point. 3. The method for three-dimensional reconstruction of the midline of the human spine as claimed in claim 1, wherein the anatomical landmarks on the back of the human body in the step C are specifically the lower carina of the human back and the posterior superior iliac spines on both sides; wherein the carina As a starting point for spine measurements. 4. the human spine midline three-dimensional reconstruction method as claimed in claim 1, is characterized in that, in the described step D, the correlation model of human back and spine midline is expressed as: x _m = x _s + L·sinθ y _m =y _s z _m = z _s + L·cosθ Among them, (x _m , y _m , z _m ) are point coordinates on the midline of the spine, (x _s , y _s , z _s ) are point coordinates on the symmetrical midline of the back of the human body, L is the length of the main body of the spine, and θ is the side of the spine bend angle. 5. the three-dimensional reconstruction method of human spine midline as claimed in claim 4, is characterized in that, the calculating formula of spine main body length in the correlation model of described human back and spine midline is specifically: L(y _s )＝0.132·T-0.035·y _s where T is the length of the spine.