Ultrasonic image three-dimensional reconstruction method

Abstract

The invention belongs to the technical field of medical image processing. The invention provides a method for constructing a three-dimensional data model by using a two-dimensional ultrasonic image. According to the method, the spatial position and attitude information of the real-time two-dimensional ultrasonic image sequence is obtained through spatial positioning, three-dimensional reconstruction is performed on the two-dimensional ultrasonic image by using a weighted average method, and the accuracy of three-dimensional reconstruction is improved. According to the method, the complexity of constructing the three-dimensional ultrasonic image is simplified, and the accuracy of three-dimensional reconstruction is improved.

Description

Technical Field

[0001] The invention relates to the field of ultrasonic imaging and is suitable for three-dimensional reconstruction of two-dimensional ultrasonic images. Background Art

[0002] Ultrasound is favored in modern medicine for its low intensity, harmless, painless and diverse display methods, especially in detecting human soft tissue.

[0003] Although ultrasound imaging technology has developed from one dimension to two dimensions, two-dimensional B-mode ultrasound imaging still has some limitations. First, two-dimensional images are flat, while human organs are three-dimensional, which requires doctors to integrate two-dimensional images into three-dimensional images in their minds. This diagnostic method is not only inefficient, but also the diagnostic results largely rely on the doctor's clinical experience, with great subjectivity and risk of misdiagnosis. Secondly, for some diseases that require volume measurement, such as prostate cancer, the measurement accuracy of two-dimensional images is low, the error is large, and it depends on subjective judgment. Finally, due to the limitations of the human body structure, two-dimensional ultrasound images of certain parts are difficult to obtain, which to a certain extent limits the accuracy of diagnosis.

[0004] 3D reconstruction technology reconstructs 2D images into 3D images, allowing doctors to post-process them on computers. This method can display 2D cross-sectional images of any direction and location without restriction, and can also save the data, so that ultrasound imaging can be simulated and reviewed even when the patient is not present. Summary of the invention

[0005] The purpose of the present invention is to provide a method for three-dimensional reconstruction of ultrasonic images. A world coordinate system is established by a spatial positioning instrument, and a sensor fixed on an ultrasonic probe is used to perform three-dimensional reconstruction of the ultrasonic image in the world coordinate system.

[0006] The technical solution of the present invention is: a world coordinate system is established through the spatial locator, the ultrasonic probe is positioned using the sensor fixed on the ultrasonic probe, the spatial position of the two-dimensional ultrasonic image is obtained in real time, the ultrasonic image of the object in different postures is scanned by the ultrasonic probe, and three-dimensional reconstruction is performed using a weighted average method.

[0007] The method of the present invention is achieved by the following steps:

[0008] 1. Establish a world coordinate system through the spatial locator, fix the sensor that can be positioned by the spatial locator at a specified position of the ultrasound probe, and ensure that the relative position between the sensor and the ultrasound probe remains unchanged.

[0009] The transformation relationship between the sensor and the imaging plane of the ultrasound probe is T sensor2us, the transformation relationship between the sensor and the spatial positioning instrument is T locator2sensor , then the transformation relationship between the spatial locator and the ultrasound probe imaging plane is T locator2us =T locator2sensor *T sensor2us After the sensor is fixed on the ultrasonic probe, the transformation relationship T sensor2us remains unchanged, the transformation relationship T locator2sensor The spatial locator locates the sensor in real time.

[0010] 2. The world coordinate system is defined as (X locator , Y locator , Z locator ), the ultrasound image is defined as (x us ,y us ). The object is imaged using the ultrasonic probe, and three-dimensional reconstruction is performed using a weighted average method, and the specific steps are as follows:

[0011] (1) When the ultrasound probe does not touch any object, the current image is recorded as a reference image for ultrasound image denoising;

[0012] (2) while using the ultrasonic probe to perform ultrasonic imaging of the target object, recording the position (X0, Y0, Z0) and posture R0 of the ultrasonic probe in the world coordinate system corresponding to each frame of the ultrasonic image until data acquisition is completed;

[0013] (3) fixing the ultrasound probe on the target object, manually selecting a region of interest on the ultrasound image, and roughly outlining the area to be reconstructed;

[0014] (4) Keeping the positions of the ultrasound probe and the target object unchanged, rotating at different angles to obtain multiple two-dimensional ultrasound images of the target area at different angles, and recording the required information according to step (2);

[0015] (5) comparing each obtained two-dimensional ultrasound image with the ultrasound image obtained in step (1) to remove noise;

[0016] (6) Traverse each 2D ultrasound image and calculate the locator2us Calculate the voxel position in space that the pixels in the region of interest should fill as follows: Transformation of the sensor to the ultrasound image

[0017] , where R is the rotation matrix and t is the translation matrix;

[0018] Calculate the physical size and spatial position of each voxel as follows:

[0019] ,in

[0020]

[0021]

[0022] (7) Traverse each voxel. If it corresponds to multiple pixels, then locate the center point of the voxel (X v , Y v , Z v ) is:

[0023] The weighted average of the voxel is calculated according to the Euclidean distance of all its internal elements, and the average value is assigned to the voxel.

[0024]

[0025] , where d is the distance and v is the grayscale value of the pixel

[0026] (8) If there are gaps in the voxels, a dilation operation is performed to fill the gaps.

[0027] The present invention provides a technical solution for three-dimensional reconstruction of ultrasonic images, which has the following advantages compared with the prior art:

[0028] This method can present the ultrasound image in the world coordinate system established by the spatial locator through the spatial locator, and perform three-dimensional reconstruction of the specified area. The implementation of this method can reconstruct ultrasound images at any position and angle in three dimensions, and can also be combined with the surgical navigation system to provide intraoperative ultrasound guidance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the technical description.

[0030] Figure 1 The figure is a flow chart of the method of the present invention.

[0031] Figure 2 This is a schematic diagram of the voxel field filling method proposed in the present invention.

[0032] Figure 3 Schematic diagram of the voxel weighted average calculation method proposed in the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the implementation and specific embodiments of the present invention; however, this is not the only form of implementing or using the specific embodiments of the present invention. The implementation covers the features of multiple specific embodiments and the method steps and sequences used to construct and operate these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences.

[0035] like Figure 1 As shown, the present invention provides a method for three-dimensional reconstruction of ultrasonic images, and the process is as follows:

[0036] 1. Establish the world coordinate system (X locator , Y locator , Z locator ), Ultrasound imaging (x us ,y us ) will eventually be transformed to the world coordinate system for 3D reconstruction. The sensor is fixed at the specified position of the ultrasound probe, and the sensor and the ultrasound probe are relatively fixed. In this way, the transformation relationship between the ultrasound image and the sensor is T sensor2us Always remain the same.

[0037] 2. The spatial locator can locate the position of the sensor in real time, and the transformation relationship between them is T locator2sensor The positioning of the sensor can be obtained in real time through the spatial locator. In this way, the transformation relationship between the ultrasound image and the spatial locator, that is, the world coordinate system, can be expressed as T locator2us =T locator2sensor *T sensor2us .

[0038] 3. Process the ultrasound image and fill the voxel field.

[0039] First, the current image is recorded when the ultrasound probe does not touch any object, which serves as a reference image for ultrasound image denoising;

[0040] In addition, while using the ultrasonic probe to perform ultrasonic imaging of the target object, the position (X0, Y0, Z0) and posture R0 of the ultrasonic probe in the world coordinate system corresponding to each frame of the ultrasonic image are recorded until the data collection is completed;

[0041] Then, fix the ultrasound probe on the target object, manually select a region of interest on the ultrasound image, and roughly outline the area to be reconstructed;

[0042] Keep the ultrasonic probe and the target object in the same position, rotate them at different angles, and obtain multiple two-dimensional ultrasonic images of the target area at different angles;

[0043] Each acquired 2D ultrasound image is compared with the reference image to remove noise;

[0044] Traverse each two-dimensional ultrasound image, according to T locator2us Calculate the voxel position in space that the pixels in the region of interest should fill ( Figure 2 ), the specific calculation is as follows:

[0045] Transformation of sensor to the ultrasound image

[0046] , where R is the rotation matrix and t is the translation matrix;

[0047] Calculate the physical size and spatial position of each voxel as follows:

[0048] ,in

[0049]

[0050]

[0051] 4. Calculate the weighted average of the voxel field.

[0052] Traverse each voxel. If it corresponds to multiple pixels, then the spatial position of the pixel to the center point of the voxel (X v , Y v , Z v )’s Euclidean distance ( Figure 3 ):

[0053]

[0054] The weighted average of the voxel is calculated according to the Euclidean distance of all its internal elements, and the average value is assigned to the voxel.

[0055]

[0056] , where d is the distance and v is the grayscale value of the pixel.

[0057] 5. If there are gaps in the voxels, perform a dilation operation to fill the gaps.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for three-dimensional reconstruction of ultrasonic images, characterized in that: The ultrasonic probe is positioned by using a spatial positioner to obtain the spatial position of a two-dimensional ultrasonic image in real time. The ultrasonic images at different positions of the object are scanned by the ultrasonic probe, and a weighted average method is used to perform three-dimensional reconstruction.

2. According to claim 1, it is characterized in that: A sensor that can be positioned by the spatial positioning device is installed at a fixed position of the ultrasonic probe, and the transformation relationship between the sensor and the imaging plane of the ultrasonic probe is T sensor2us , the transformation relationship between the sensor and the spatial positioning instrument is T locator2sensor , then the transformation relationship between the spatial locator and the ultrasound probe imaging plane is T locator2us =T locator2sensor *T sensor2us After the sensor is fixed on the ultrasonic probe, the transformation relationship T sensor2us remains unchanged, the transformation relationship T locator2sensor The spatial locator locates the sensor in real time.

3. According to claim 1, it is characterized in that: The object is imaged using the ultrasonic probe, and three-dimensional reconstruction is performed using a weighted average method. The specific steps are as follows: (1) When the ultrasound probe does not touch any object, the current image is recorded as a reference image for ultrasound image denoising; (2) Use the ultrasonic probe to perform ultrasonic imaging of the target object, and at the same time, record the T corresponding to the current ultrasonic image. locator2us ; (3) Fixing the ultrasound probe, manually selecting a region of interest, and roughly outlining the area to be reconstructed; (4) Keeping the position of the ultrasonic probe and the target object unchanged, rotate them at different angles to obtain multiple two-dimensional ultrasonic images of the target area at different angles, and record the corresponding T locator2us ; (5) comparing each obtained two-dimensional ultrasound image with the ultrasound image obtained in step (1) to remove noise; (6) Traverse each 2D ultrasound image and calculate the locator2us Calculate the voxel positions in space that pixels in the region of interest should fill; (7) Traverse each voxel. If it corresponds to multiple pixels, calculate the weighted average of the voxels based on the Euclidean distance from the spatial position of the pixel to the center of the voxel; (8) If there are gaps in the voxels, a dilation operation is performed to fill the gaps.

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