1. A method for determining the thickness of a transparent layer behind the neck of a fetus based on an ultrasound image, the method comprising:

acquiring an image block containing a cervical posterior transparent layer region from a fetal ultrasonic image;

extracting the outline of the image block to obtain a first outline set;

identifying the contour line of the upper transparent belt and the contour line of the lower transparent belt from the first contour line set;

and identifying the maximum distance between the contour line of the upper transparent belt and the contour line of the lower transparent belt as the thickness of the region of the transparent layer behind the neck.

2. The method of claim 1, wherein identifying the contour lines of the upper and lower transparent bands from the first set of contour lines comprises:

identifying the type of each contour line in the first contour line set;

if the nonlinear contour line exists, the nonlinear contour line is divided into linear contour lines;

according to the characteristics of the transparent layer area behind the neck, the contour line of the upper transparent belt and the contour line of the lower transparent belt are searched from a second contour line set formed by all linear contour lines;

wherein the characteristic of the transparent layer region includes a dark liquid region between the upper transparent band and the lower transparent band.

3. The method of claim 2, wherein said segmenting said non-linear contour lines into linear contour lines comprises:

for the nonlinear contour, determining a range of an abscissa and a range of an ordinate of the nonlinear contour;

traversing the nonlinear outline according to the range of the abscissa;

when the horizontal coordinates are the same, determining the contour line formed by the pixel points with the large vertical coordinate as the contour line of the lower transparent belt;

determining the contour line formed by the pixel points with small vertical coordinates as the contour line of the upper transparent belt;

the contour line of the upper transparent belt and the contour line of the lower transparent belt are the divided linear contour lines.

4. The method of claim 2, wherein said finding the contour lines of said upper transparent band and said lower transparent band from the second set of contour lines of each rectilinear contour line based on the characteristics of the region of said retrocervical transparent band comprises

Determining a first center coordinate of each contour line in the second contour line set;

identifying pixel point categories on the upper side and the lower side of two adjacent profiles of the vertical coordinates of the first central coordinate;

if the pixel point categories on the upper side and the lower side of the two profiles accord with the characteristics of the transparent region behind the neck, classifying the two profiles into the contour lines of the upper transparent band and the contour lines of the lower transparent band according to the vertical coordinates of the two profiles;

the transparent layer area is characterized in that the types of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line in the two contour lines are background points, and the types of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line are foreground points.

5. The method of claim 4, wherein determining the first center coordinate of each contour line in the second set of contour lines comprises:

determining the horizontal coordinate range and the vertical coordinate range of each contour in the second contour line;

determining the maximum value and the minimum value of the abscissa of each contour line according to the abscissa range;

determining the maximum value and the minimum value of the ordinate of each contour line according to the range of the ordinate;

the mean value of the maximum value and the minimum value of the abscissa is the abscissa of the first central coordinate, and the mean value of the maximum value and the minimum value of the ordinate is the ordinate of the first central coordinate.

6. The method of claim 2, wherein identifying the type of each contour line in the first set of contour lines comprises:

for each contour line in the first contour line set, respectively executing:

determining the coordinates of a second central point of the contour line;

respectively taking at least one coordinate point meeting preset conditions from two sides of the second central point, wherein the preset conditions comprise that the difference value between the abscissa of the taken coordinate point and the abscissa of the second central point meets a preset difference value;

taking the second central point and a line parallel to the longitudinal direction where each coordinate point is located as a reference line;

determining the intersection point of each reference line and the contour line;

obtaining the type of the contour line based on the number of the intersection points of each reference line;

if the number of the intersection points of at least one reference line is less than two points, the contour line type is a linear type;

and if the number of the intersection points of each reference line is more than or equal to two points, the contour line type is nonlinear.

7. The method of claim 4, wherein the region of the transparent layer behind the neck is a foreground point, the points outside the region of the transparent layer behind the neck are background points, and the determining whether the pixel point categories on the upper and lower sides of the two contour lines conform to the characteristics of the region of the transparent layer behind the neck comprises:

according to the two contour lines, the contour line with a small longitudinal coordinate value in the first central coordinate is used as an upper contour line, and the other contour line is used as a lower contour line;

if the pixel point categories on the upper side and the lower side of the two contour lines meet preset conditions, determining that the characteristics of the transparent layer region behind the neck are met;

if the pixel point categories on the upper side and the lower side of the two contour lines do not meet the preset condition, determining that the characteristics of the transparent layer region behind the neck are not met;

the preset conditions include: the types of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line are background points, and the types of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line are foreground points.

8. The method of claim 1, wherein the identifying a maximum distance between the contour line of the upper transparent band and the contour line of the lower transparent band as the thickness of the region of the transparent layer behind the neck comprises:

calculating the average slope of the upper contour line and the lower contour line;

determining two coordinate points of the contour line of the upper transparent belt and the contour line of the lower transparent belt in the normal direction of the average slope to obtain a coordinate point pair;

and determining the distance between the coordinate point pair with the maximum distance as the thickness of the transparent layer region behind the neck.

9. The method according to claim 8, wherein said determining two coordinate points of the contour lines of the upper transparent band and the lower transparent band in the normal direction of the average slope to obtain a pair of coordinate points comprises:

|(Y_up-K′X_up)-(Y_down-K′X_down) Less than or equal to C; wherein K ═ 1/K, K is the average slope, Y_upIs the ordinate, Y, of a coordinate point on the contour line of the upper transparent tape_downIs the ordinate, X, of a coordinate point on the contour line of the lower transparent band_upIs the abscissa, X, of a coordinate point on the contour line of the upper transparent band_downC is a first preset value, and is the abscissa of a coordinate point on the contour line of the lower transparent belt.

10. An apparatus for determining the thickness of a transparent layer behind the neck of a fetus based on an ultrasound image, the apparatus comprising a controller, a first memory, and a second memory:

the first memory for storing a computer program executable by the controller;

the second memory is used for buffering input signals;

the controller, coupled to the first memory and the second memory, is configured to perform the method of any of claims 1-9.

Background

Compared with a mode of screening fetal genetic diseases by genes, the technology for screening the thickness of the transparent layer behind the neck of the fetus by prenatal ultrasound is a quick, safe and radiationless method, and has important values in the aspects of clinical application and market share. Clinical NT measurements are affected by the skill level of the operator, the imaging performance of the ultrasound equipment, and physical factors of the pregnant woman and fetus, and therefore, how to exclude these effects is an important direction for various studies.

The process of realizing the automatic measurement and calculation of the thickness of the transparent layer behind the neck of the fetus by two-dimensional ultrasound in the early pregnancy before delivery involves a plurality of technical difficulties: (1) how to eliminate the interference of factors such as different imaging styles, physical constitutions of pregnant women and fetuses and the like on image segmentation under ultrasonic equipment of different models; (2) how to perform accurate segmentation of the NT-ROI region; (3) how to rapidly and automatically position the upper and lower layer edges of the NT; (4) how to accurately locate the thickest positions of the upper and lower edge layers of the NT. Due to the technical difficulties, the NT automatic measurement technology in the prior art has the problems of insufficient generalization capability on different ultrasonic equipment or inaccurate NT thickness calculation.

Disclosure of Invention

The invention aims to provide a method and a related device for determining the thickness of a transparent layer behind a fetal neck based on an ultrasonic image, which are used for calculating the thickness of the transparent layer behind the fetal neck.

In a first aspect, an embodiment of the present application provides a method for making a retrocervical stratum lucidum of a fetus, including:

acquiring an image block containing a cervical posterior transparent layer region from a fetal ultrasonic image;

extracting the outline of the image block to obtain a first outline set;

identifying the contour line of the upper transparent belt and the contour line of the lower transparent belt from the first contour line set;

and identifying the maximum distance between the contour line of the upper transparent belt and the contour line of the lower transparent belt as the thickness of the region of the transparent layer behind the neck.

In one embodiment, the identifying the contour lines of the upper transparent band and the contour lines of the lower transparent band from the first contour line set comprises:

identifying the type of each contour line in the first contour line set;

if the nonlinear contour line exists, the nonlinear contour line is divided into linear contour lines;

according to the characteristics of the transparent layer area behind the neck, the contour line of the upper transparent belt and the contour line of the lower transparent belt are searched from a second contour line set formed by all linear contour lines;

wherein the characteristic of the transparent layer region includes a dark liquid region between the upper transparent band and the lower transparent band.

In one embodiment, the dividing the non-linear contour line into linear contour lines includes:

for the nonlinear contour, determining a range of an abscissa and a range of an ordinate of the nonlinear contour;

traversing the nonlinear outline according to the range of the abscissa;

when the horizontal coordinates are the same, determining the contour line formed by the pixel points with the large vertical coordinate as the contour line of the lower transparent belt;

determining the contour line formed by the pixel points with small vertical coordinates as the contour line of the upper transparent belt;

the contour line of the upper transparent belt and the contour line of the lower transparent belt are the divided linear contour lines.

In one embodiment, the finding the contour lines of the upper transparent band and the contour lines of the lower transparent band from the second contour line set of the linear contour lines according to the characteristics of the region of the transparent layer behind the neck includes:

determining a first center coordinate of each contour line in the second contour line set;

identifying pixel point categories on the upper side and the lower side of two adjacent profiles of the vertical coordinates of the first central coordinate;

if the pixel point categories on the upper side and the lower side of the two profiles accord with the characteristics of the transparent region behind the neck, classifying the two profiles into the contour lines of the upper transparent band and the contour lines of the lower transparent band according to the vertical coordinates of the two profiles;

the transparent layer area is characterized in that the types of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line in the two contour lines are background points, and the types of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line are foreground points.

In one embodiment, the determining the first center coordinates of each contour line in the second set of contour lines comprises:

determining the horizontal coordinate range and the vertical coordinate range of each contour in the second contour line;

determining the maximum value and the minimum value of the abscissa of each contour line according to the abscissa range;

determining the maximum value and the minimum value of the ordinate of each contour line according to the range of the ordinate;

the mean value of the maximum value and the minimum value of the abscissa is the abscissa of the first central coordinate, and the mean value of the maximum value and the minimum value of the ordinate is the ordinate of the first central coordinate.

In one embodiment, the identifying the type of each contour line in the first set of contour lines comprises:

for each contour line in the first contour line set, respectively executing:

determining the coordinates of a second central point of the contour line;

respectively taking at least one coordinate point meeting preset conditions from two sides of the second central point, wherein the preset conditions comprise that the difference value between the abscissa of the taken coordinate point and the abscissa of the second central point meets a preset difference value;

taking the second central point and a line parallel to the longitudinal direction where each coordinate point is located as a reference line;

determining the intersection point of each reference line and the contour line;

obtaining the type of the contour line based on the number of the intersection points of each reference line;

if the number of the intersection points of at least one reference line is less than two points, the contour line type is a linear type;

and if the number of the intersection points of each reference line is more than or equal to two points, the contour line type is nonlinear.

In one embodiment, the determining whether the pixel point categories on the upper and lower sides of the two contour lines conform to the characteristics of the transparent region behind the neck includes:

according to the two contour lines, the contour line with a small longitudinal coordinate value in the first central coordinate is used as an upper contour line, and the other contour line is used as a lower contour line;

if the pixel point categories on the upper side and the lower side of the two contour lines meet preset conditions, determining that the characteristics of the transparent layer region behind the neck are met;

if the pixel point categories on the upper side and the lower side of the two contour lines do not meet the preset condition, determining that the characteristics of the transparent layer region behind the neck are not met;

the preset conditions include: the types of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line are background points, and the types of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line are foreground points.

In one embodiment, the identifying a maximum distance between the contour line of the upper transparent band and the contour line of the lower transparent band as the thickness of the transparent layer region behind the neck includes:

calculating the average slope of the upper contour line and the lower contour line;

determining two coordinate points of the contour line of the upper transparent belt and the contour line of the lower transparent belt in the normal direction of the average slope to obtain a coordinate point pair;

and determining the distance between the coordinate point pair with the maximum distance as the thickness of the transparent layer region behind the neck.

In one embodiment, the determining two coordinate points of the contour line of the upper transparent band and the contour line of the lower transparent band in the normal direction of the average slope to obtain a coordinate point pair includes:

|(Y_up-K′X_up)-(Y_down-K′X_down) Less than or equal to C; wherein K ═ 1/K, K is the average slope, Y_upIs the ordinate, Y, of a coordinate point on the contour line of the upper transparent tape_downIs the ordinate, X, of a coordinate point on the contour line of the lower transparent band_upIs the abscissa, X, of a coordinate point on the contour line of the upper transparent band_downC is a first preset value, and is the abscissa of a coordinate point on the contour line of the lower transparent belt.

Second aspect the present application also provides an apparatus for making a retrocervical stratum lucidum layer of a fetus, the apparatus comprising a controller, a first memory, a second memory:

the first memory for storing a computer program executable by the controller;

the second memory is used for buffering input signals;

the controller is connected with the first memory and the second memory and is configured to execute the step of obtaining an image block containing a cervical back transparent layer area from a fetal ultrasonic image;

extracting the outline of the image block to obtain a first outline set;

identifying the contour line of the upper transparent belt and the contour line of the lower transparent belt from the first contour line set;

and identifying the maximum distance between the contour line of the upper transparent belt and the contour line of the lower transparent belt as the thickness of the region of the transparent layer behind the neck.

In one embodiment, the identifying the contour lines of the upper transparent band and the contour lines of the lower transparent band from the first contour line set comprises:

identifying the type of each contour line in the first contour line set;

if the nonlinear contour line exists, the nonlinear contour line is divided into linear contour lines;

according to the characteristics of the transparent layer area behind the neck, the contour line of the upper transparent belt and the contour line of the lower transparent belt are searched from a second contour line set formed by all linear contour lines;

wherein the characteristic of the transparent layer region includes a dark liquid region between the upper transparent band and the lower transparent band.

In one embodiment, the dividing the non-linear contour line into linear contour lines includes:

for the nonlinear contour, determining a range of an abscissa and a range of an ordinate of the nonlinear contour;

traversing the nonlinear outline according to the range of the abscissa;

when the horizontal coordinates are the same, determining the contour line formed by the pixel points with the large vertical coordinate as the contour line of the lower transparent belt;

determining the contour line formed by the pixel points with small vertical coordinates as the contour line of the upper transparent belt;

the contour line of the upper transparent belt and the contour line of the lower transparent belt are the divided linear contour lines.

In one embodiment, the finding the contour lines of the upper transparent band and the contour lines of the lower transparent band from the second contour line set of the linear contour lines according to the characteristics of the region of the transparent layer behind the neck includes:

determining a first center coordinate of each contour line in the second contour line set;

identifying pixel point categories on the upper side and the lower side of two adjacent profiles of the vertical coordinates of the first central coordinate;

if the pixel point categories on the upper side and the lower side of the two profiles accord with the characteristics of the transparent region behind the neck, classifying the two profiles into the contour lines of the upper transparent band and the contour lines of the lower transparent band according to the vertical coordinates of the two profiles;

the transparent layer area is characterized in that the types of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line in the two contour lines are background points, and the types of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line are foreground points.

In one embodiment, the determining the first center coordinates of each contour line in the second set of contour lines comprises:

determining the horizontal coordinate range and the vertical coordinate range of each contour in the second contour line;

determining the maximum value and the minimum value of the abscissa of each contour line according to the abscissa range;

determining the maximum value and the minimum value of the ordinate of each contour line according to the range of the ordinate;

the mean value of the maximum value and the minimum value of the abscissa is the abscissa of the first central coordinate, and the mean value of the maximum value and the minimum value of the ordinate is the ordinate of the first central coordinate.

In one embodiment, the identifying the type of each contour line in the first set of contour lines comprises:

for each contour line in the first contour line set, respectively executing:

determining the coordinates of a second central point of the contour line;

respectively taking at least one coordinate point meeting preset conditions from two sides of the second central point, wherein the preset conditions comprise that the difference value between the abscissa of the taken coordinate point and the abscissa of the second central point meets a preset difference value;

taking the second central point and a line parallel to the longitudinal direction where each coordinate point is located as a reference line;

determining the intersection point of each reference line and the contour line;

obtaining the type of the contour line based on the number of the intersection points of each reference line;

if the number of the intersection points of at least one reference line is less than two points, the contour line type is a linear type;

and if the number of the intersection points of each reference line is more than or equal to two points, the contour line type is nonlinear.

In one embodiment, the determining whether the pixel point categories on the upper and lower sides of the two contour lines conform to the characteristics of the transparent region behind the neck includes:

according to the two contour lines, the contour line with a small longitudinal coordinate value in the first central coordinate is used as an upper contour line, and the other contour line is used as a lower contour line;

if the pixel point categories on the upper side and the lower side of the two contour lines meet preset conditions, determining that the characteristics of the transparent layer region behind the neck are met;

if the pixel point categories on the upper side and the lower side of the two contour lines do not meet the preset condition, determining that the characteristics of the transparent layer region behind the neck are not met;

the preset conditions include: the types of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line are background points, and the types of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line are foreground points.

In one embodiment, the identifying a maximum distance between the contour line of the upper transparent band and the contour line of the lower transparent band as the thickness of the transparent layer region behind the neck includes:

calculating the average slope of the upper contour line and the lower contour line;

determining two coordinate points of the contour line of the upper transparent belt and the contour line of the lower transparent belt in the normal direction of the average slope to obtain a coordinate point pair;

and determining the distance between the coordinate point pair with the maximum distance as the thickness of the transparent layer region behind the neck.

In one embodiment, the determining two coordinate points of the contour line of the upper transparent band and the contour line of the lower transparent band in the normal direction of the average slope to obtain a coordinate point pair includes:

|(Y_up-K′X_up)-(Y_down-K′X_down) Less than or equal to C; wherein K ═ 1/K, K is the average slope, Y_upIs the ordinate, Y, of a coordinate point on the contour line of the upper transparent tape_downIs the ordinate, X, of a coordinate point on the contour line of the lower transparent band_upIs the abscissa, X, of a coordinate point on the contour line of the upper transparent band_downC is a first preset value, and is the abscissa of a coordinate point on the contour line of the lower transparent belt.

The method for calculating the thickness of the transparent layer behind the neck of the fetus provided by the embodiment of the application realizes automatic measurement, greatly relieves the working pressure of an ultrasonic doctor and improves the screening efficiency.

Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the application. The objectives and other advantages of the application may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a view of an application scenario of a method for determining thickness of a transparent layer behind a fetal neck based on an ultrasound image according to an embodiment of the present application;

fig. 2 is a schematic diagram of a fetal ultrasound image of a method for determining thickness of a posterior hyaloid layer of a fetal neck based on an ultrasound image according to an embodiment of the present application;

fig. 3 is an image block diagram of a retrocervical stratum lucidum region of a method for determining thickness of a retrocervical stratum lucidum of a fetus according to an embodiment of the present application;

fig. 4 is an overall flowchart of a method for determining thickness of the hyaloid layer of the fetal neck based on an ultrasound image according to an embodiment of the present application;

fig. 5 is a schematic diagram of a first contour line set obtained by a method for determining thickness of a transparent layer behind a neck of a fetus according to an embodiment of the present application;

fig. 6 is a schematic diagram of a method for determining the thickness of the posterior hyaloid layer of the fetal neck according to the embodiment of the present application, in which the contour lines of the upper and lower zona pellucida are identified from the first contour line set;

fig. 7 is a schematic diagram illustrating a method for determining thickness of a posterior hyaloid layer of a fetal neck according to an embodiment of the present application, which determines the type of each contour line in a first set of contour lines;

fig. 8 is a schematic diagram illustrating a second center point coordinate of a contour line of a method for determining a thickness of a posterior transjugular layer of a fetus according to an embodiment of the present application;

fig. 9 is a schematic diagram of the second center point P being respectively located at the left and right sides in the method for determining the thickness of the opaque layer behind the fetal neck according to the embodiment of the present application;

fig. 10 is a schematic diagram of a contour line of a method for determining the thickness of the hyaloid layer of the fetal neck based on an ultrasound image according to an embodiment of the present application;

fig. 11 is a schematic diagram of a method for segmenting a contour line for determining the thickness of the transparent layer behind the neck of a fetus according to an embodiment of the present application;

fig. 12 is a schematic diagram of a method for determining the thickness of the posterior hyaloid layer of the fetal neck according to the embodiment of the present application, which finds the contour lines of the upper and lower zona pellucida from the second contour line set;

fig. 13 is a schematic view of a retrocervical stratum lucidum region of a method for determining thickness of a retrocervical stratum lucidum based on an ultrasound image according to an embodiment of the present application;

fig. 14 is a schematic diagram of a plurality of pairs of contours of a method for determining thickness of a transparent layer behind a fetal neck based on an ultrasound image according to an embodiment of the present application;

fig. 15 is a schematic diagram of determining the thickness of the transparent layer behind the neck according to the method for determining the thickness of the transparent layer behind the neck of the fetus provided by the embodiment of the present application;

fig. 16 is a K of a method for determining thickness of the hyaloid layer of the back of the neck of a fetus based on an ultrasound image according to an embodiment of the present application_UPThe meaning of each parameter in the formula is determined.

Detailed Description

In order to make the technical solutions of the present application better understood by those of ordinary skill in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

It is noted that the terms "first," "second," and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

The inventor researches and discovers that the prenatal ultrasonic screening technology of the thickness of the transparent layer behind the neck of the fetus is a quick, safe and radiationless method compared with a gene screening mode of genetic diseases of the fetus, and has important values in the aspects of clinical application and market share. Clinical NT measurements are affected by the skill level of the operator, the imaging performance of the ultrasound equipment, and physical factors of the pregnant woman and fetus, and therefore, how to exclude these effects is an important direction for various studies.

The process of realizing the automatic measurement and calculation of the thickness of the transparent layer behind the neck of the fetus by two-dimensional ultrasound in the early pregnancy before delivery involves a plurality of technical difficulties: (1) how to eliminate the interference of factors such as different imaging styles, physical constitutions of pregnant women and fetuses and the like on image segmentation under ultrasonic equipment of different models; (2) how to perform accurate segmentation of the NT-ROI region; (3) how to rapidly and automatically position the upper and lower layer edges of the NT; (4) how to accurately locate the thickest positions of the upper and lower edge layers of the NT. Due to the technical difficulties, the NT automatic measurement technology in the prior art has the problems of insufficient generalization capability on different ultrasonic equipment or inaccurate NT thickness calculation.

The inventor studies to find that the retrocervical stratum lucidum is a fluid translucent protein film surrounding the back of the fetal neck. In the ultrasonic prenatal examination of the early pregnancy stage within 11-13 weeks, the thickness of the retrojugular diaphragmatic layer of the fetus is an important biological parameter for judging whether the fetus has diseases such as Down's syndrome, cardiovascular system abnormality, nervous system malformation and the like. Taking Down syndrome as an example, the incidence rate of the Down syndrome accounts for about 1% of the number of people who are pregnant, the birth rate is about 1/700-1/600, and the proportion still has certain scalability. Due to the comprehensive release of the domestic two-fetus policy, the ultrasonic prenatal examination pressure of the fetus born by hospitals at all levels is increasing day by day.

In view of this, the present application provides a method and a related apparatus for determining a thickness of a transparent layer behind a fetal neck based on an ultrasound image, so as to determine the thickness of the transparent layer behind the fetal neck, thereby relieving the working pressure of an sonographer and improving the efficiency of prenatal screening. The inventive concept of the present application can be summarized as follows: acquiring an image block containing a cervical posterior transparent layer region from a fetal ultrasonic image; carrying out contour extraction on the image block and identifying the contour line of the upper transparent belt and the contour line of the lower transparent belt; the maximum distance between the contour line of the upper transparent tape and the contour line of the lower transparent tape is taken as the thickness of the transparent layer area behind the neck.

Fig. 1 is a view showing an application scenario of the method for determining the thickness of the transparent layer behind the fetal neck based on the ultrasound image in the embodiment of the present application. The figure includes: network 10, server 20, storage 30, terminal device 40; wherein:

the fetal ultrasound image is stored in the memory 30, when the thickness of the transparent layer behind the fetal neck is determined, the server 20 acquires the fetal ultrasound image from the memory 30 through the network 10, and the image block of the transparent layer area behind the neck is acquired in the fetal ultrasound image and then the outline of the image block is extracted to obtain a first outline set; identifying the contour line of the upper transparent belt and the contour line of the lower transparent belt from the first contour line set; the maximum distance between the contour line of the upper transparent band and the contour line of the lower transparent band is identified as the thickness of the transparent layer region behind the neck. It should be noted that the above steps may also be performed by the terminal device 40.

Only a single server or terminal device is detailed in the description of the present application, but it will be understood by those skilled in the art that the terminal device 40, the server 20 and the memory 30 shown are intended to represent the operations of the terminal device, the server and the memory involved in the technical aspects of the present disclosure. The individual servers and memories are described in detail for convenience of illustration only and are not meant to imply limitations on the number, type, or location of end devices and servers. It should be noted that the underlying concepts of the example embodiments of the present application may not be altered if additional modules are added or removed from the illustrated environments. In addition, although fig. 1 shows a bidirectional arrow from the memory 30 to the server 20 for convenience of explanation, it will be understood by those skilled in the art that the above-described data transmission and reception also need to be implemented through the network 10.

It should be noted that the storage in the embodiment of the present application may be, for example, a cache system, or a hard disk storage, a memory storage, and the like. In addition, the method for determining the thickness of the transparent layer behind the fetal neck based on the ultrasonic image is not only suitable for the application scene shown in fig. 1, but also suitable for any device with the requirement for determining the thickness of the transparent layer behind the fetal neck.

For the convenience of understanding, the method for determining the thickness of the transparent layer behind the fetal neck based on the ultrasound image provided by the embodiment of the present application is described in detail below with reference to the accompanying drawings.

Images meeting the measurement conditions are screened according to the standard published by the british national Fetal Medicine Foundation (FMF). Wherein the image standards published by FMF are: (1) the middle sagittal section view shows that the neck is in a natural state; (2) the head and the chest occupy 70% -85% of the whole graphic area; (3) displaying the nasal bone; (4) displaying a nose tip skin line; (5) displaying the maxilla; (6) showing the chin, etc. A standard Nuchal Transparency (NT) image is shown in fig. 2.

The image patch containing the retrocervical zona pellucida region obtained from the fetal ultrasound image shown in fig. 2 is shown in fig. 3, in which the thickness of the NT region is the thickest of the upper and lower edges of the retrocervical zona pellucida. The starting points of the two regions are located at the junction of the dark liquid area of the retrocervical zona pellucida and the soft tissue and the junction of the dark liquid area of the retrocervical zona pellucida and the fetal skin respectively, as shown by arrows in fig. 3. The anatomical structures above and below the NT region are the cervical vertebrae in the darker echogenic region, the bright echogenic fetal soft tissue, the anechoic retrocervical zonal hyaloid dark fluid region, the bright echogenic fetal skin, and the anechoic uterine amniotic fluid region in sequence.

As shown in fig. 4, an overall flowchart for determining the thickness of the transparent layer behind the fetal neck based on the ultrasound image is provided in the embodiment of the present application:

the current methods for NT region segmentation mainly include methods based on traditional image segmentation methods such as threshold class and deformation model, and segmentation model methods based on deep learning. The traditional segmentation algorithm, for example, based on a deformation model method, has a segmentation effect depending on the selection of an initialization position, and if an initialization region is far away from a target segmentation region, an energy function is easy to fall into a local minimum value; meanwhile, due to lack of certain topological adaptability, parameters set for the global image may not be optimized to some local information, and further, the subsequent complete extraction of the NT contour line is affected. Segmentation based on the deep learning method completely depends on the training set, thereby resulting in higher labor labeling cost. In addition, in practical situations, the constitution of the pregnant women and the fetal position are limited to be different from person to person, so that the generalization capability of the deep learning model of the pregnant women in practical situations needs to be enhanced. Meanwhile, since the ultrasonic devices of different manufacturers and different models have different noise modes which are difficult to detect and count, the segmentation model learned by the training set is acquired under one machine, and the accuracy performance of the ultrasonic devices of other models is greatly reduced.

Moreover, as can be seen from fig. 2 and fig. 3, the NT region has a smaller region proportion in the whole ultrasound image, and the time consumption of the whole algorithm and the occupation of computing resources are considered, so that the present application is implemented by using a region of interest (ROI) preselection mode as a precondition. Namely in step 401: acquiring an image block containing a cervical posterior transparent layer region from a fetal ultrasonic image;

in step 402: carrying out contour extraction on the image block to obtain a first contour line set;

because the imaging quality of the NT-ROI area is influenced by factors such as an ultrasonic machine, the constitution of a pregnant woman, the development condition of a fetus and the like, the important characteristics of the resolution and the contrast of the ROI image are different from person to person and from machine to machine. Meanwhile, the factors also influence the echo characteristics of structures such as cervical vertebrae, soft tissues, upper and lower edge profiles of NT of the fetus. The histogram feature of an image can reflect the basic characteristics of the whole strong and weak response distribution points of the image. Therefore, by analyzing the distribution characteristics of the pixel response histogram of the NT-ROI area pre-selected by a doctor, the application selects a Gaussian mixture model based on statistical characteristics to characterize the probability distribution characteristics of different pixel classes in the NT-ROI so as to exclude the influence of machine factors, the constitution of pregnant women and other uncontrollable variables. In the embodiment of the application, the support doctor freely adjusts the position and the size of the ROI preselected frame, so that the flexibility is high from the use perspective of the doctor.

In the embodiment of the present application, the contour extraction of the image block to obtain the first contour line set may specifically be implemented as the steps shown in fig. 5:

since the ultrasonic waves interfere with each other inside the human body, noise points with randomly distributed brightness are formed when reflected in the image. The existence of noise has a large influence on the subsequent image segmentation and edge extraction, so for this randomly distributed speckle noise, in step 501: denoising the image block to obtain a denoised image block;

for ease of understanding, the gaussian distribution parameter solving problem employed in the present application is first described below:

from the central limit theorem, a large number of independent random variables which are distributed uniformly are also distributed gaussian normally as a whole. Therefore, the segmentation of the image block after noise reduction is considered as modeling to solve the problem of two Gaussian distribution parameters, and then the final binary mask image is obtained.

For single-channel Gaussian distribution, setting the corresponding mean value as mu, the variance as sigma, and the input pixel point as x, including:

for a multidimensional Gaussian distribution, there areWhere Θ is { μ, ∑ is a parameter set of gaussian distribution, μ is an input D-dimensional mean column vector, and Σ is an input dx D-dimensional covariance matrix. Where D represents the number of feature dimensions of x, and if only a single-channel grayscale image pixel value is used as an input feature, D is 1. If the RGB color channel feature is used, D is 3, where μ is a 1-row, 3-column vector with each element representing the color mean of one channel and Σ is a 3 × 3 matrix with each element representing the pixel value covariance between each color channel. For a certain pixel point, the probability distribution of the pixel value is combined by two types of Gaussian distributions, and for a single pixel point, the probability distribution is as follows:

wherein pi ═ a₁，a₂，...，a_K}，a_jIs a pixel x_iA prior probability of belonging to the kth gaussian distribution that satisfies the following constraint:0≤a_j≤1。

in step 502: performing K-means clustering algorithm operation on the denoised image blocks to obtain a primary segmentation result of the image blocks;

in step 503: calculating the preliminary segmentation result by adopting a maximum expectation algorithm to obtain the segmentation result of the image block;

in step 504: acquiring a binary mask image of the segmentation result, and performing edge extraction operation on the binary mask image to obtain an edge image;

in step 505: and carrying out contour line extraction on the edge image to obtain a contour line set.

In one embodiment, the method of erosion expansion is firstly adopted for the edge image, so that the separated and isolated edge points are eliminated, and meanwhile, the disconnected edge line segments are fused to obtain the complete edge line. And then, based on the topological structure analysis thought of boundary tracking, all contour lines in the edge image are extracted, and further a first contour line set is obtained.

Identifying contour lines of the upper transparent band and contour lines of the lower transparent band from the first contour line set in step 403;

in one embodiment, the step of identifying the contour lines of the upper transparent band and the contour lines of the lower transparent band from the first contour line set may be implemented as the following steps:

in step 601: identifying the type of each contour line in the first contour line set;

in the embodiment of the present application, for each contour line in the first contour line set, the steps shown in fig. 7 are respectively performed:

in step 701: determining the coordinates of a second central point of the contour line;

in one embodiment, as shown in fig. 8, the maximum value and the minimum value in the X direction and the Y direction of the image are calculated, that is, the value range of the coordinates in the X direction and the value range in the Y direction are: [ X ]_min，X_max]，[Y_min，Y_max]. The second center point coordinate P is: p ═[(X_min+X_max)/2，(Y_min+Y_max)/2]。

In step 702: respectively taking at least one coordinate point meeting preset conditions from two sides of the second central point, wherein the preset conditions comprise that the difference value between the abscissa of the taken coordinate point and the abscissa of the second central point meets a preset difference value;

in one embodiment, as shown in fig. 9, P1, P2 satisfying a preset condition are taken at left and right sides with respect to the second center point P, respectively; in the embodiment of the present application, the difference between the abscissa of the coordinate point and the abscissa of the second central point is 1/3 × L, wherein L ═ X is determined by experiments of those skilled in the art_max-X_min。

In step 703: taking the second central point and a line parallel to the longitudinal direction where each coordinate point is located as a reference line;

in step 704: determining the intersection point of each reference line and the contour line;

in step 705: and obtaining the type of the contour line based on the number of the intersection points of the reference lines.

If the number of the intersection points of at least one reference line is less than two points, the contour line type is a linear type; if the number of the intersection points of each reference line is more than or equal to two points, the contour line type is nonlinear.

In one embodiment, the extracted contour shape is not fixed in a single mode due to the contour shape of the dark fluid region within the NT zona pellucida, and the boundary resolution of each tissue within the ROI region, which varies with the machine and maternal body and fetal development. Through the test and analysis of actual data, three main contour line shapes in the graph 10 are summarized; in the figure, the number of the intersection points of at least one reference line in the contour line 1 is less than two, so that the contour line 1 is linear; the number of the intersection points of the reference lines of the contour lines 2 and 3 is greater than or equal to two points, so that the contour lines 2 and 3 are nonlinear.

In one embodiment, to facilitate subsequent identification of the contours of the upper and lower transparent bands, in step 602: if the non-linear contour line exists, the non-linear contour line is divided into linear contour lines.

As shown in fig. 11, the contour lines 2 and 3 in fig. 10 are divided, and the contour lines 2 and 3 are processed into straight contour lines.

In step 603: according to the characteristics of the transparent layer area behind the neck, the contour lines of the upper transparent belt and the contour lines of the lower transparent belt are searched from a second contour line set formed by all the linear contour lines; wherein the transparent layer region is characterized by a dark liquid region between the upper and lower transparent bands. In one embodiment, it may be implemented as the steps shown in FIG. 12:

since the non-linear contour lines are divided into linear contour lines, for more precise subsequent calculation, the first center coordinates of each contour line in the second contour line set are recalculated, so in step 1201: determining first center coordinates of all contour lines in the second contour line set;

in step 1202: identifying pixel point categories on the upper side and the lower side of two profiles adjacent to the vertical coordinate of the first central coordinate;

in step 1203: if the pixel point categories on the upper side and the lower side of the two profiles accord with the characteristics of the transparent region behind the neck, classifying the two profiles into the contour lines of the upper transparent band and the lower transparent band according to the vertical coordinates of the two profiles; the transparent layer area is characterized in that the types of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line in the two contour lines are background points, and the types of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line are foreground points.

In an embodiment, as shown in fig. 13, the transparent layer region behind the neck is a foreground point, the points outside the transparent layer region behind the neck are background points, and the determining whether the pixel point categories on the upper and lower sides of the two contour lines conform to the characteristics of the transparent layer region behind the neck may specifically be implemented as:

according to the two contour lines, the contour line with a small longitudinal coordinate value in the first central coordinate is used as an upper contour line, and the other contour line is used as a lower contour line; if the pixel point categories on the upper side and the lower side of the two contour lines meet the preset conditions, determining that the characteristics of the transparent layer region behind the neck are met; if the pixel point categories on the upper side and the lower side of the two contour lines do not meet the preset condition, determining that the characteristics of the transparent layer region behind the neck are not met;

the preset conditions include: the classification of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line is a background point, and the classification of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line is a foreground point.

In one embodiment, whether a pixel belongs to the foreground or the background can be determined by calculating mask values of the first center coordinates of the upper and lower contour lines in the Y and-Y directions, as formula 1:

V_Binary＝I_Binary(P. + -. P (0, η)) (equation 1);

wherein, V_BinaryFor mask values, P is the first center coordinate of each contour, and η is a positive integer constant (in the examples of this application, η can be 2-4, as determined experimentally by those skilled in the art)

In the embodiment of the present application, the upper contour line and the lower contour line are obtained by the above method, and in one embodiment, as shown in fig. 14, there are a plurality of upper contour lines and a plurality of lower contour lines, and for this case, a pair of contour lines closest to the center position of the NT region is selected as the upper contour line and the lower contour line.

In step 404: the maximum distance between the contour line of the upper transparent band and the contour line of the lower transparent band is identified as the thickness of the transparent layer region behind the neck. The method can be specifically implemented as the steps shown in fig. 15:

in step 1501: calculating the average slope of the upper and lower contour lines; as shown in equation 2:

wherein K is the average slope, KUP is the fitting slope of the upper contour line, and KDown is the fitting slope of the lower contour line.

The determination method of KUP is shown in equation 3:

the meaning of each parameter is shown in fig. 16.

In step 1502: determining two coordinate points of the contour line of the upper transparent belt and the contour line of the lower transparent belt in the normal direction of the average slope to obtain a coordinate point pair;

in the embodiment of the present application, a coordinate point pair is obtained by using formula 4:

when|(Y_up-K’X_Up)-(Y_Down-K’X_Down) C (formula 4)

Wherein K ═ 1/K, K is the average slope, Y_upIs the ordinate, Y, of a coordinate point on the contour line of the upper transparent tape_downIs the ordinate, X, of a coordinate point on the contour line of the lower transparent band_upIs the abscissa, X, of a coordinate point on the contour line of the upper transparent band_downC is a positive integer, and can be 3-5 as determined by experiments of those skilled in the art.

In step 1503: the distance between the pair of coordinate points with the largest distance is determined as the thickness of the transparent layer region behind the neck.

After the method for calculating the thickness of the transparent layer behind the fetal neck provided by the embodiment of the present application is introduced, the electronic device for calculating the thickness of the transparent layer behind the fetal neck provided by the embodiment of the present application will be described in detail based on the same inventive concept:

the apparatus includes a controller, a first memory, a second memory:

the first memory for storing a computer program executable by the controller;

the second memory is used for buffering input signals;

the controller is connected with the first memory and the second memory and is configured to execute the step of obtaining an image block containing a cervical back transparent layer area from a fetal ultrasonic image;

extracting the outline of the image block to obtain a first outline set;

identifying the contour line of the upper transparent belt and the contour line of the lower transparent belt from the first contour line set;

and identifying the maximum distance between the contour line of the upper transparent belt and the contour line of the lower transparent belt as the thickness of the region of the transparent layer behind the neck.

In one embodiment, the identifying the contour lines of the upper transparent band and the contour lines of the lower transparent band from the first contour line set comprises:

identifying the type of each contour line in the first contour line set;

if the nonlinear contour line exists, the nonlinear contour line is divided into linear contour lines;

according to the characteristics of the transparent layer area behind the neck, the contour line of the upper transparent belt and the contour line of the lower transparent belt are searched from a second contour line set formed by all linear contour lines;

wherein the characteristic of the transparent layer region includes a dark liquid region between the upper transparent band and the lower transparent band.

In one embodiment, the dividing the non-linear contour line into linear contour lines includes:

for the nonlinear contour, determining a range of an abscissa and a range of an ordinate of the nonlinear contour;

traversing the nonlinear outline according to the range of the abscissa;

when the horizontal coordinates are the same, determining the contour line formed by the pixel points with the large vertical coordinate as the contour line of the lower transparent belt;

determining the contour line formed by the pixel points with small vertical coordinates as the contour line of the upper transparent belt;

the contour line of the upper transparent belt and the contour line of the lower transparent belt are the divided linear contour lines.

In one embodiment, the finding the contour lines of the upper transparent band and the contour lines of the lower transparent band from the second contour line set of the linear contour lines according to the characteristics of the region of the transparent layer behind the neck includes:

determining a first center coordinate of each contour line in the second contour line set;

identifying pixel point categories on the upper side and the lower side of two adjacent profiles of the vertical coordinates of the first central coordinate;

if the pixel point categories on the upper side and the lower side of the two profiles accord with the characteristics of the transparent region behind the neck, classifying the two profiles into the contour lines of the upper transparent band and the contour lines of the lower transparent band according to the vertical coordinates of the two profiles;

the transparent layer area is characterized in that the types of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line in the two contour lines are background points, and the types of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line are foreground points.

In one embodiment, the determining the first center coordinates of each contour line in the second set of contour lines comprises:

determining the horizontal coordinate range and the vertical coordinate range of each contour in the second contour line;

determining the maximum value and the minimum value of the abscissa of each contour line according to the abscissa range;

determining the maximum value and the minimum value of the ordinate of each contour line according to the range of the ordinate;

the mean value of the maximum value and the minimum value of the abscissa is the abscissa of the first central coordinate, and the mean value of the maximum value and the minimum value of the ordinate is the ordinate of the first central coordinate.

In one embodiment, the identifying the type of each contour line in the first set of contour lines comprises:

for each contour line in the first contour line set, respectively executing:

determining the coordinates of a second central point of the contour line;

respectively taking at least one coordinate point meeting preset conditions from two sides of the second central point, wherein the preset conditions comprise that the difference value between the abscissa of the taken coordinate point and the abscissa of the second central point meets a preset difference value;

taking the second central point and a line parallel to the longitudinal direction where each coordinate point is located as a reference line;

determining the intersection point of each reference line and the contour line;

obtaining the type of the contour line based on the number of the intersection points of each reference line;

if the number of the intersection points of at least one reference line is less than two points, the contour line type is a linear type;

and if the number of the intersection points of each reference line is more than or equal to two points, the contour line type is nonlinear.

In one embodiment, the determining whether the pixel point categories on the upper and lower sides of the two contour lines conform to the characteristics of the transparent region behind the neck includes:

according to the two contour lines, the contour line with a small longitudinal coordinate value in the first central coordinate is used as an upper contour line, and the other contour line is used as a lower contour line;

if the pixel point categories on the upper side and the lower side of the two contour lines meet preset conditions, determining that the characteristics of the transparent layer region behind the neck are met;

if the pixel point categories on the upper side and the lower side of the two contour lines do not meet the preset condition, determining that the characteristics of the transparent layer region behind the neck are not met;

the preset conditions include: the types of the pixel points on the upper side of the upper contour line and the lower side of the lower contour line are background points, and the types of the pixel points on the lower side of the upper contour line and the upper side of the lower contour line are foreground points.

In one embodiment, the identifying a maximum distance between the contour line of the upper transparent band and the contour line of the lower transparent band as the thickness of the transparent layer region behind the neck includes:

calculating the average slope of the upper contour line and the lower contour line;

determining two coordinate points of the contour line of the upper transparent belt and the contour line of the lower transparent belt in the normal direction of the average slope to obtain a coordinate point pair;

and determining the distance between the coordinate point pair with the maximum distance as the thickness of the transparent layer region behind the neck.

In one embodiment, the determining two coordinate points of the contour line of the upper transparent band and the contour line of the lower transparent band in the normal direction of the average slope to obtain a coordinate point pair includes:

|(Y_up-K′X_up)-(Y_down-K′X_down) Less than or equal to C; wherein K ═ 1/K, K is the average slope, Y_upIs the ordinate, Y, of a coordinate point on the contour line of the upper transparent tape_downIs the ordinate, X, of a coordinate point on the contour line of the lower transparent band_upIs the abscissa, X, of a coordinate point on the contour line of the upper transparent band_downC is a first preset value, and is the abscissa of a coordinate point on the contour line of the lower transparent belt.

It should be noted that although several units or sub-units of the apparatus are mentioned in the above detailed description, such division is merely exemplary and not mandatory. Indeed, the features and functions of two or more units described above may be embodied in one unit, according to embodiments of the application. Conversely, the features and functions of one unit described above may be further divided into embodiments by a plurality of units.

Further, while the operations of the methods of the present application are depicted in the drawings in a particular order, this does not require or imply that these operations must be performed in this particular order, or that all of the illustrated operations must be performed, to achieve desirable results. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step execution, and/or one step broken down into multiple step executions.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.