CN113990459A - Method for full-automatically measuring lower sternum end/xiphoid process in CT/MRI volume - Google Patents

Abstract

The invention discloses a method for fully automatically measuring the lower sternum end/xiphoid process in CT/MRI volume, which comprises the following steps: s1, cutting off the part below the middle axis plane in the whole body CT/MRI image to obtain an upper half body image; s2, cutting off the part of the upper body image behind the middle coronal plane to obtain a pre-search image; s3, setting a lower threshold LT and an upper threshold UT, and setting voxel values in a region [ LT, UT ] in the pre-search image as foreground pixels; s4, establishing a coordinate system and placing the pre-search image in the coordinate system; s5, searching the slices from the topmost slice; s6, in the current slice, finding a foreground pixel which is located around the middle sagittal plane and has the lowest i coordinate; if the slice is found, selecting the next level slice to continue searching; if not found, the selection is finished; and S7, finally determining the position of the lower sternum end or the xiphoid process in the pre-search image.

Description

Method for full-automatically measuring lower sternum end/xiphoid process in CT/MRI volume

Technical Field

The invention relates to the field of medical images, in particular to a method for fully automatically measuring the lower sternum end/xiphoid process in a CT/MRI volume.

Background

The lower Sternum (SIE) or Xiphoid Process (XP) adjacent thereto is a bone structure that is easily detected (by simple palpation) in the human thorax and is often used as a reference marker for different medical applications. However, in the prior art, the lower sternum end or xiphoid process is usually found in CT/MRI (magnetic resonance imaging) images by using a manual resolution method, which is complicated in operation and seriously affects the working efficiency of medical image operation, so that it is necessary to research a method for automatically measuring the lower sternum end or xiphoid process in CT/MRI images to solve the above problems.

Disclosure of Invention

The invention aims to solve the problems and provides a convenient and quick method for fully automatically measuring the lower sternum end/xiphoid process in a CT/MRI volume.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method for fully automatically measuring the lower sternal/xiphoid process in a CT/MRI volume, comprising the steps of:

s1, cutting off the part below the middle axis plane in the whole body CT/MRI image to obtain an upper half body image;

s2, cutting off the part of the upper body image behind the middle coronal plane to obtain a pre-search image;

s3, setting a lower threshold LT and an upper threshold UT, setting voxel values in the interval [ LT, UT ] in the pre-search image as foreground pixels, and setting voxel values outside the interval [ LT, UT ] in the pre-search image as background pixels;

s4, establishing a coordinate system and placing the pre-search image in the coordinate system;

s5, horizontally slicing the pre-search image from top to bottom, and searching slices from the topmost slice;

s6, in the current slice, finding a foreground pixel which is located around the middle sagittal plane and has the lowest i coordinate; if the slice is found, selecting the next level slice to continue searching; if not found, the selection is finished;

s7, finally determining that the position of the lower end of the sternum or the xiphoid process in the pre-search image is SIE ═ i (k-1), MSP, k-1; where i (k-1) represents the i coordinate found in the previous slice and k-1 represents the next slice.

Further, in step S3, the lower threshold LT is WL-WW/2, and the upper threshold UT is WL + WW/2; where WL and WW are statistical estimation constants that retain only bone tissue.

Compared with the prior art, the invention has the advantages and positive effects that:

according to the invention, the whole image of the human body is cut, so that the data processing amount is reduced, and the image data is less affected than the breastbone in a mixing way, thereby facilitating the processing and analysis of the breastbone image and improving the image processing efficiency and the processing precision; then, the positions of the lower ends of the sternums or the xiphoid process are confirmed finally by distinguishing foreground pixels and background pixels and searching each level of slices; the effect of automatically detecting the position of the lower end of the sternum or the xiphoid process is achieved, the working efficiency of medical image operation is improved, and convenience is brought to medical image work.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic diagram of a coordinate system;

FIG. 2 is a schematic diagram of the location of the xiphoid process in the image;

FIG. 3 is a schematic view of the location of the xiphoid process in a horizontal slice;

fig. 4 is a diagram showing a positional relationship of a plurality of slices on a coordinate system.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived from the embodiments of the present invention by a person skilled in the art without any creative effort, should be included in the protection scope of the present invention.

As shown in fig. 1 to 4, the present embodiment discloses a method for fully automatically measuring the lower sternum/xiphoid process in a CT/MRI volume, the search for the lower Sternum (SIE) is performed in a slice-by-slice search in the top-down direction within a stack of axial CT/MRI slices conforming to a volume scan (size MxNxH).

The process is mainly divided into two stages:

1. pretreatment of

1.1, cutting

1.1.1, because SIE is positioned in the rib, it always exists in the upper half of the scanning, so the lower half is cut off at the Middle Axis Plane (MAP) to obtain the upper body image; this helps to improve throughput (due to the smaller throughput).

1.1.2, to eliminate the potential deeper (than sternum) confusion, we cut out the back of the mid-coronal plane (MCP), resulting in pre-search images;

1.2 binarization

1.2.1, setting a Lower Threshold (LT) and an Upper Threshold (UT), and setting voxel values in a range interval [ LT, UT ] in the pre-search image as foreground pixels (1), otherwise, setting the voxel values as background pixels (0).

1.2.2、LT＝WL-WW/2，UT＝WL+WW/2；

Where WL and WW are statistical estimation constants that retain only bone tissue.

2. Searching

2.1, establishing a coordinate system and placing the pre-search image in the coordinate system; in the coordinate system, the width direction of the human body (i.e., the left-right direction of the human body) is taken as the X-axis, the thickness direction of the human body (i.e., the front-back direction of the human body) is taken as the Y-axis, and the height of the human body (i.e., the up-down direction of the human body) is taken as the Z-axis;

2.2, horizontally slicing the pre-search image from top to bottom, searching the slices one by one from the top to bottom direction, and starting from the slice k ═ H;

2.3, in the current slice, finding foreground pixels (1) located around the midsagittal plane (MSP) and having the lowest i-coordinate; if the slice is found, the next level slice (k is k-1) is selected to continue searching; if not found, the selection is finished; the i-coordinate represents the horizontal line in the graph, and the lowest i-coordinate is the lowest line of the CT section of the human body with effective image pixels, as shown in FIG. 1.

After the image is finished, finally determining the position of the lower end of the sternum or the xiphoid process in the pre-search image as [ i (k-1), MSP, k-1 ]; where i (k-1) represents the i coordinate found in the previous slice and k-1 represents the next slice. The position of the SIE is a 3D coordinate position and corresponds to (x, y, z), i.e., x ═ i (k-1), y ═ MSP, and z ═ k-1.

According to the invention, the whole image of the human body is cut, so that the data processing amount is reduced, and the image data is less affected than the breastbone in a mixing way, thereby facilitating the processing and analysis of the breastbone image and improving the image processing efficiency and the processing precision; then, the positions of the lower ends of the sternums or the xiphoid process are confirmed finally by distinguishing foreground pixels and background pixels and searching each level of slices; the effect of automatically detecting the position of the lower end of the sternum or the xiphoid process is achieved, the working efficiency of medical image operation is improved, and convenience is brought to medical image work.

Claims (2)

1. A method for fully automatically measuring the lower sternum/xiphoid process in a CT/MRI volume is characterized in that: the method comprises the following steps:

s1, cutting off the part below the middle axis plane in the whole body CT/MRI image to obtain an upper half body image;

s2, cutting off the part of the upper body image behind the middle coronal plane to obtain a pre-search image;

s3, setting a lower threshold LT and an upper threshold UT, setting voxel values in the interval [ LT, UT ] in the pre-search image as foreground pixels, and setting voxel values outside the interval [ LT, UT ] in the pre-search image as background pixels;

s4, establishing a coordinate system and placing the pre-search image in the coordinate system;

s5, horizontally slicing the pre-search image from top to bottom, and searching slices from the topmost slice;

s6, in the current slice, finding a foreground pixel which is located around the middle sagittal plane and has the lowest i coordinate; if the slice is found, selecting the next level slice to continue searching; if not found, the selection is finished;

s7, finally determining that the position of the lower end of the sternum or the xiphoid process in the pre-search image is SIE ═ i (k-1), MSP, k-1; where i (k-1) represents the i coordinate found in the previous slice and k-1 represents the next slice.

2. The method of fully automatically measuring the substernal/xiphoid process within a CT/MRI volume of claim 1, wherein: in step S3, the lower threshold LT is WL-WW/2, and the upper threshold UT is WL + WW/2; where WL and WW are statistical estimation constants that retain only bone tissue.

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