Thermal strain imaging method, system and device

Abstract

The invention discloses a thermal strain imaging method, a thermal strain imaging system and a thermal strain imaging device, and belongs to the field of ultrasonic imaging. Extracting baseline displacement of the feature points; finding a typical frame of the detection object at the end of contraction and diastole as a global reference frame i0; finding out a typical frame in at the last stage of contraction and relaxation of the detection object in each group of heated data In; calculating a correlation coefficient between the typical frame in and the global reference frame i0, calculating a relative displacement between the typical frame in and the global reference frame i0, and generating a displacement gradient map Gn according to the correlation coefficient and the relative displacement; converting the displacement gradient map into a strain map to obtain a thermal strain image of the cross section of the detected object, and detecting the offset of tissues such as water-containing tissues and lipids in echo signals by utilizing the characteristic of echo displacement gradient generated by sound velocity change caused by temperature rise, so as to judge the change gradient distribution of sound velocity and judge the tissue components. The tissue and organ detection accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic imaging, and in particular to a thermal strain imaging method, system and device. Background Art

[0002] Ultrasound is an imaging and treatment technology widely used in clinical practice. The generation, transmission and reception of ultrasound are radiation-free and have good biosafety. Ultrasound is penetrating and can scan tissues and organs within a certain depth. By analyzing the ultrasound echo signal, its characteristics can be qualitatively or quantitatively evaluated.

[0003] Intravascular ultrasound (IVUS) is the gold standard for detecting vascular plaques. Conventional IVUS reconstructs ultrasound echo signals into grayscale images and analyzes the composition of vascular plaques through image features. It relies on subjective experience and its accuracy needs to be improved. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide a thermal strain imaging method that can improve the accuracy of tissue and organ detection within a certain depth.

[0005] In order to overcome the deficiencies of the prior art, a second object of the present invention is to provide a thermal strain imaging system that can improve the accuracy of tissue and organ detection within a certain depth.

[0006] In order to overcome the deficiencies of the prior art, a third object of the present invention is to provide a thermal strain imaging device that can improve the accuracy of tissue and organ detection within a certain depth.

[0007] One of the purposes of the present invention is achieved by the following technical solution:

[0008] A thermal strain imaging method comprises the following steps:

[0009] Image acquisition: collect the ultrasonic image of the test object before heating 0 , heat the test object, and collect ultrasonic images of the test object when it is heated to different temperatures. n , n is an integer;

[0010] Extract the baseline displacement of the feature point: Based on the ultrasonic image data before and after heating {I n}, select the salient points of the detected object as feature points, and heat the data before I 0 The first frame is taken as a reference, and the displacement of the feature point minus the offset introduced by the respiratory pulse is obtained to obtain the true displacement of the feature point in each subsequent frame. The baseline displacement of the feature point is extracted based on the true displacement;

[0011] Get the global reference frame: Find the typical frames of the end-systole and end-diastole of the detected object as the global reference frame i 0;

[0012] Get a typical frame: According to the baseline displacement of the feature points, find each group of heated data I n Typical frames of the detected object at the end of systole and diastole i n ;

[0013] Generating displacement gradient maps: Calculating the data after heating I n Typical frame i n With the global reference frame i 0 The correlation coefficient between them is calculated to calculate the typical frame i in each group of heated data. n With the global reference frame i 0 The relative displacement of the displacement gradient map G is generated according to the correlation coefficient and the relative displacement. n ;

[0014] Obtain thermal strain imaging: Convert the displacement gradient map into a strain map, perform visualization, and obtain thermal strain imaging of the cross section of the test object.

[0015] Furthermore, in the image acquisition step, a heating transducer array is used to heat the detection object, and an imaging transducer is used to acquire an ultrasonic image of the detection object.

[0016] Furthermore, the heating transducer array and the imaging transducer work alternately.

[0017] Furthermore, in the image acquisition step, an ultrasonic image of the detection object is acquired by pulse waves, and the detection object is heated by continuous waves.

[0018] Furthermore, the thermal strain imaging method also includes a detection object positioning step, which is located before the image acquisition step. The detection object positioning step is specifically: the imaging transducer works to acquire an ultrasonic image, and the heating transducer array and the imaging transducer move until the ultrasonic image is an ultrasonic image of the detection object.

[0019] Furthermore, in the baseline displacement step of extracting feature points, when the detection object is a blood vessel, the salient points are the vascular endothelium, the vascular adventitia, and the plaque contour.

[0020] The second object of the present invention is achieved by adopting the following technical solution:

[0021] A thermal strain imaging system, used to implement any one of the above thermal strain imaging methods, the thermal strain imaging system comprising

[0022] An imaging module, wherein the imaging module excites an ultrasonic pulse signal and generates an ultrasonic beam, and collects an echo signal reflected by the detection object to form an ultrasonic image;

[0023] A heating module, wherein the heating module heats the detection object to make the detection object reach a preset temperature;

[0024] An analysis module is used to analyze the ultrasonic image of the detection object before heating and the ultrasonic images at different temperatures after heating to form thermal strain imaging of a cross section of the detection object.

[0025] The third object of the present invention is achieved by adopting the following technical solution:

[0026] A thermal strain imaging device is used to implement any one of the above-mentioned thermal strain imaging methods, the thermal strain imaging device comprises a flexible shaft, a transducer base, an imaging transducer and a heating device, the transducer base is installed at the end of the flexible shaft, the flexible shaft drives the transducer base to rotate, and the imaging transducer and the heating device are installed on the transducer base.

[0027] Furthermore, the heating device is a heating transducer array, and the heating transducer array is evenly installed around the transducer base.

[0028] Furthermore, the upper surface of the heating transducer array is arc-shaped.

[0029] Compared with the prior art, the thermal strain imaging method of the present invention collects the ultrasonic image of the detected object before heating. 0 , heat the test object, and collect ultrasonic images of the test object when it is heated to different temperatures. n , n is an integer; according to the ultrasonic data before and after heating {I n}, select the salient points of the detected object as feature points, and heat the data before I 0 The first frame of the image is used as a reference, and the displacement of the feature point minus the offset introduced by the respiratory pulse is used to obtain the true displacement of the feature point in each subsequent frame. The baseline displacement of the feature point is extracted based on the true displacement; the typical frames of the end of contraction and diastole of the detected object are found as the global reference frame i 0 ; According to the baseline displacement of the characteristic points, find each group of heated data I n Typical frames of the detected object at the end of systole and diastole i n ; Calculate the data after heating I n Typical frame i n With the global reference frame i 0 The correlation coefficient between them is calculated to calculate the typical frame i in each group of heated data. n With the global reference frame i 0 The relative displacement of the displacement gradient map G is generated according to the correlation coefficient and the relative displacement. n; The displacement gradient map is converted into a strain map and visualized to obtain thermal strain imaging of the cross section of the test object. The characteristic of the echo displacement gradient caused by the change in sound velocity due to the increase in temperature is used, and then the echo signals before and after heating are compared and analyzed to detect the offset of water-containing tissues and lipids in the echo signals, thereby determining the gradient distribution of the sound velocity change, distinguishing the tissue composition, and improving the accuracy of tissue and organ detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a flow chart of the thermal strain imaging method of the present invention;

[0031] Figure 2 is a schematic diagram of a thermal strain imaging device of the present invention;

[0032] Figure 3 for Figure 2 Schematic diagram of a heating transducer array of a thermal strain imaging device;

[0033] Figure 4 Schematic diagram of the working process of the thermal strain imaging device.

[0034] In the figure: 1. Transducer base; 2. Heating transducer array; 3. Ultrasound imaging transducer; 4. Blood vessel wall. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0037] Biological tissues contain a lot of water, which has a thermal effect. The same tissue has different acoustic properties at different temperatures. Temperature changes will cause changes in the speed of sound propagation in the tissue. The echo displacement gradient caused by the change in sound speed due to temperature increase is called ultrasonic thermal strain. There are differences in the thermal strain of different tissues. For example, the water content in muscle tissue is greater than that in fat. Therefore, by heating the tissue and imaging and analyzing its thermal strain, tissue differentiation can be achieved. The thermal strain imaging method of this application is based on the above principle.

[0038] See also Figure 1 The present invention provides a thermal strain imaging method, comprising the following steps:

[0039] Image acquisition: collect the ultrasonic image of the test object before heating 0 , heat the test object, and collect ultrasonic images of the test object when it is heated to different temperatures. n , n is an integer;

[0040] Extract the baseline displacement of the feature point: Based on the ultrasonic image data before and after heating {I n}, select the salient points of the detected object as feature points, and heat the data before I 0 The first frame is taken as a reference, and the displacement of the feature point minus the offset introduced by the respiratory pulse is obtained to obtain the true displacement of the feature point in each subsequent frame. The baseline displacement of the feature point is extracted based on the true displacement;

[0041] Get the global reference frame: Find the typical frames of the end-systole and end-diastole of the detected object as the global reference frame i 0 ;

[0042] Get a typical frame: According to the baseline displacement of the feature points, find each group of heated data I n Typical frames of the detected object at the end of systole and diastole i n ;

[0043] Generating displacement gradient maps: Calculating the data after heating I n Typical frame i n With the global reference frame i 0 The correlation coefficient between them is calculated to calculate the typical frame i in each group of heated data. n With the global reference frame i 0 The relative displacement of the displacement gradient map G is generated according to the correlation coefficient and the relative displacement. n ;

[0044] Obtain thermal strain imaging: Convert the displacement gradient map into a strain map, perform visualization, and obtain thermal strain imaging of the cross section of the test object.

[0045] Specifically, the thermal strain imaging method further includes a detection object positioning step, which is located before the image acquisition step, and the detection object positioning step is specifically: the imaging transducer works to acquire an ultrasonic image, and the heating device and the imaging transducer move until the ultrasonic image is an ultrasonic image of the detection object. During the movement of the heating device and the imaging transducer, the imaging transducer can work continuously or at fixed intervals.

[0046] The image acquisition step is specifically as follows: when the heating device and the imaging transducer are moved to the detection object, the imaging transducer works first to acquire the ultrasonic image of the detection object when it is not heated.0 , then the heating device starts to work, heats the detection object, and the imaging transducer collects the ultrasonic image after heating. Specifically, the number of ultrasonic images collected by the imaging transducer after heating is multiple, and the multiple ultrasonic images after heating correspond to different heating temperatures. In this embodiment, the corresponding different heating temperatures are achieved by controlling the heating time. When the heating device is a heating transducer array, in order to avoid interference of the heating transducer array with the imaging transducer, the heating transducer array and the imaging transducer work alternately. When the heating device is a microwave or other form of heating structure, the heating device and the imaging transducer can work at the same time, that is, the heating device is always heating, and the imaging transducer works at a preset interval to collect ultrasonic images of the detection object at different temperatures. When the heating device is a heating transducer array, the imaging transducer collects the ultrasonic image of the detection object through a pulse wave, and the heating transducer array heats the detection object through a continuous wave. In this embodiment, the pulse wave is a square wave, the operating frequency is 12-60MHz, and the output voltage is 100V. The continuous wave is a continuous sine wave, the operating frequency is 1-3.5MHz, the pulse excitation period is 60-280ms, the output voltage is 20-60V, and the duty cycle is 30-50%.

[0047] In the step of extracting the baseline displacement of feature points, when the detection object is a blood vessel, the significant points are the vascular intima, vascular adventitia, and plaque contour. Ultrasonic thermal strain is of great value in the detection of vascular diseases. Intravascular plaques are produced due to various factors such as lipid deposition or fibrosis. The composition of plaques is complex, including one or more complex components such as calcification, lipids, and fibrosis. Among them, the lipid component has a greater impact on the vulnerability of the plaque, so accurately distinguishing lipids and other components in vascular plaques has very important clinical value. The baseline displacement of the extracted feature points is specifically extracted using feature analysis methods such as time domain, frequency domain, and wavelet domain. When the detection object is a blood vessel, the baseline displacement of the feature point is the vasodilation caused by the pulse.

[0048] In the step of generating the displacement gradient map, the cross-correlation method is used to calculate the heated data I n Typical frame i n With the global reference frame i 0 The correlation coefficient between .

[0049] In the step of obtaining thermal strain imaging, the displacement gradient map is converted into a strain map by using methods such as differential filtering.

[0050] Please continue reading Figure 2 The present application also discloses a thermal strain imaging device for implementing the above-mentioned thermal strain imaging method. The thermal strain imaging device includes a flexible shaft, a transducer base 1, an imaging transducer 3 and a heating device 2.

[0051] The transducer base 1 is used to fix the heating device 2 and the imaging transducer 3. During the imaging process, the transducer base 1 is driven by the flexible shaft to rotate, thereby realizing annular imaging. The rotation of the flexible shaft is driven by a handle, and a rotary motor and an encoder are arranged in the handle.

[0052] The heating device 2 is used to heat the surrounding tissue to generate thermal strain. In this embodiment, the heating device 2 uses a heating transducer array, and the heating transducer array is evenly installed on the periphery of the transducer base 1. Figure 3 As shown, the upper surface of the heating transducer array is arc-shaped, which is used to focus the sound beam and improve the heating efficiency. It can be used with an acoustic lens to further improve the focusing effect. The heating transducer array is evenly arranged on the transducer base 1, distributed in a circular array according to the circumference, and the focus of the heating transducer array is kept in the same cross section, such as Figure 4 As shown. Thus, the tissue of the cross section is evenly and fully heated during the rotation process. When the detection object is a blood vessel, the gray area is the blood vessel wall 4, and the transducer rotates in the blood vessel cavity to heat the wall interface and image it. The number of heating transducers arranged in the array can be adjusted according to actual conditions, and the center frequency is within a certain range (such as 1-3.5MHz). The output performance of the heating transducer must meet the human safety threshold.

[0053] The number of the imaging transducer 3 can be one or more, and the ultrasonic radio frequency signal of the complete cross section can be obtained after completing one rotation. The center frequency of the imaging transducer 3 is selected according to the situation (such as a single frequency of 12MHz, 20MHz, 40MHz, 60MHz, etc., or a dual center frequency or even a multi-center frequency transducer).

[0054] The present application also relates to a thermal strain imaging system for implementing the above-mentioned thermal strain imaging method. The thermal strain imaging system includes

[0055] Imaging module: The imaging module excites ultrasonic pulse signals and generates ultrasonic beams, collects echo signals reflected by the detection object to form ultrasonic images. The pulse wave is a square wave, the operating frequency is 12-60MHz, and the output voltage is 100V.

[0056] The heating module heats the detection object so that the detection object reaches a preset temperature. In the present embodiment, the heating module is a heating transducer array. The heating module is responsible for exciting the ultrasonic pulse signal, exciting the ultrasonic heating transducer to generate a sound beam, and heating the target tissue. Its emission waveform, operating frequency, pulse excitation period, output voltage, duty cycle, etc. are adjusted as appropriate. In the present embodiment, the continuous wave is a continuous sine wave, the operating frequency is 1-3.5MHz, the pulse excitation period is 60-280ms, the output voltage is 20-60V, and the duty cycle is 30-50%. Each channel of the heating control module controls one or more heating transducers. In addition to adjusting the waveform parameters, the number of channels in which the heating module works can also be adjusted to increase or decrease the number of working heating transducers to adjust the heating effect.

[0057] The analysis module analyzes the ultrasonic image of the detection object before heating and the ultrasonic images at different temperatures after heating to form thermal strain imaging of the cross section of the detection object.

[0058] During the thermal strain imaging process, the heating module and the imaging module work alternately to generate ultrasonic images before heating. 0 and the ultrasonic image data I after the nth heating n The imaging module works in the form of pulse waves, with one working cycle consisting of sending and receiving a complete ultrasonic pulse radio frequency signal. The heating module works in the form of continuous waves, and the time of each working cycle can be adjusted (such as 10ms-2s), depending on the specific situation. The system will switch between the imaging and heating modules according to the preset instructions. Increasing the energy delivery voltage can achieve the same heating temperature in a shorter time, thereby reducing the time difference between imaging before and after heating and reducing interference such as tissue displacement.

[0059] Compared with the prior art, the thermal strain imaging method of the present invention collects the ultrasonic image of the detected object before heating. 0 , heat the test object, and collect ultrasonic images of the test object when it is heated to different temperatures. n , n is an integer; according to the ultrasonic data before and after heating {I n}, select the salient points of the detected object as feature points, and heat the data before I 0 The first frame of the image is used as a reference, and the displacement of the feature point minus the offset introduced by the respiratory pulse is used to obtain the true displacement of the feature point in each subsequent frame. The baseline displacement of the feature point is extracted based on the true displacement; the typical frames of the end of contraction and diastole of the detected object are found as the global reference frame i 0 ; According to the baseline displacement of the characteristic points, find each group of heated data I n Typical frames of the detected object at the end of systole and diastole i n ; Calculate the data after heating I n Typical frame i nWith the global reference frame i 0 The correlation coefficient between them is calculated to calculate the typical frame i in each group of heated data. n With the global reference frame i 0 The relative displacement of the displacement gradient map G is generated according to the correlation coefficient and the relative displacement. n ; The displacement gradient map is converted into a strain map and visualized to obtain thermal strain imaging of the cross section of the test object. The characteristic of the echo displacement gradient caused by the change in sound velocity due to the increase in temperature is used, and then the echo signals before and after heating are compared and analyzed to detect the offset of water-containing tissues and lipids in the echo signals, thereby determining the gradient distribution of the sound velocity change, distinguishing the tissue composition, and improving the accuracy of tissue and organ detection.

[0060] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which are equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of them belong to the protection scope of the present invention.

Claims

1. A thermal strain imaging method, characterized in that: The following steps are involved: Image acquisition: collect the ultrasonic image I0 of the test object before heating, heat the test object, and collect the ultrasonic images I0 of the test object when it is heated to different temperatures. n , n is an integer; Extract the baseline displacement of the feature point: Based on the ultrasonic image data before and after heating {I n }, select the salient points of the detected object as feature points, take the first frame of the data I0 before heating as a reference, subtract the offset introduced by the respiratory pulse from the displacement of the feature point to obtain the true displacement of the feature point in each subsequent frame, and extract the baseline displacement of the feature point based on the true displacement; Obtaining the global reference frame: Find the typical frames of the end-systole and end-diastole of the detected object as the global reference frame i0; Get a typical frame: According to the baseline displacement of the feature points, find each group of heated data I n Typical frames of the detected object at the end of systole and diastole i n ; Generating displacement gradient maps: Calculating the data after heating I n Typical frame i n The correlation coefficient between the global reference frame i0 and the typical frame i in each set of heated data is calculated. n The relative displacement with the global reference frame i0 generates the displacement gradient map G according to the correlation coefficient and the relative displacement n ; Obtain thermal strain imaging: Convert the displacement gradient map into a strain map, perform visualization, and obtain thermal strain imaging of the cross section of the test object.

2. The thermal strain imaging method according to claim 1, characterized in that: In the image acquisition step, a heating transducer array is used to heat the detection object, and an imaging transducer is used to acquire an ultrasonic image of the detection object.

3. The thermal strain imaging method according to claim 2, characterized in that: The heating transducer array and the imaging transducer work alternately.

4. The thermal strain imaging method according to claim 2, characterized in that: In the image acquisition step, an ultrasonic image of the detection object is acquired by pulse waves, and the detection object is heated by continuous waves.

5. The thermal strain imaging method according to claim 2, characterized in that: The thermal strain imaging method also includes a detection object positioning step, which is located before the image acquisition step. The detection object positioning step is specifically: the imaging transducer works to acquire an ultrasonic image, and the heating transducer array and the imaging transducer move until the ultrasonic image is an ultrasonic image of the detection object.

6. The thermal strain imaging method according to claim 1, characterized in that: In the baseline displacement step of extracting feature points, when the detection object is a blood vessel, the salient points are the vascular endothelium, the vascular adventitia, and the plaque contour.

7. A thermal strain imaging system for implementing the thermal strain imaging method according to any one of claims 1 to 6, characterized in that: The thermal strain imaging system comprises An imaging module, wherein the imaging module excites an ultrasonic pulse signal and generates an ultrasonic beam, and collects an echo signal reflected by the detection object to form an ultrasonic image; A heating module, wherein the heating module heats the detection object to make the detection object reach a preset temperature; An analysis module is used to analyze the ultrasonic image of the detection object before heating and the ultrasonic images at different temperatures after heating to form thermal strain imaging of a cross section of the detection object.

8. A thermal strain imaging device for implementing the thermal strain imaging method according to any one of claims 1 to 6, characterized in that: The thermal strain imaging device comprises a flexible shaft, a transducer base, an imaging transducer and a heating device. The transducer base is installed at the end of the flexible shaft. The flexible shaft drives the transducer base to rotate. The imaging transducer and the heating device are installed on the transducer base.

9. The thermal strain imaging device according to claim 8, characterized in that: The heating device is a heating transducer array, and the heating transducer array is evenly installed around the transducer base.

10. The thermal strain imaging device according to claim 8, characterized in that: The upper surface of the heating transducer array is arc-shaped.

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