Thermal strain imaging method, system and device

Abstract

The present invention discloses a thermal strain imaging method, system and device, which belongs to the field of ultrasonic imaging. The method collects ultrasonic images of the detection object before and after heating; extracts the baseline displacement of the characteristic points; finds the typical frames of the detection object at the end of contraction and diastole as the global reference frame i0; finds the data of each group after heating i1. n Typical frames i of the detected object at the end of systole and diastole n ; Calculate typical frame i n The correlation coefficient between the global reference frame i0 and the typical frame i is calculated n The relative displacement with the global reference frame i0 generates the displacement gradient map G according to the correlation coefficient and relative displacement n ; Convert the displacement gradient map into a strain map to obtain thermal strain imaging of the cross section of the test object. Utilize the echo displacement gradient caused by the change in sound velocity due to temperature increase to detect the offset of water-containing tissues and lipids in the echo signal, thereby determining the gradient distribution of sound velocity changes, discriminating tissue composition, and improving the accuracy of tissue and organ detection.

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 a widely used imaging and therapeutic technique in clinical practice. Ultrasound generation, transmission, and reception are all radiation-free, ensuring good biosafety. Ultrasound is penetrating, capable of scanning tissues and organs at depths. Analysis of ultrasound echo signals allows for qualitative and quantitative assessment of their characteristics.

[0003] Intravascular ultrasound (IVUS) is the gold standard for detecting vascular plaques. Conventional IVUS reconstructs ultrasound echo signals into grayscale images and analyzes vascular plaque components based on image features. This 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 I0 of the test object before heating, heat the test object, and collect the ultrasonic images I0 of the test object when 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 detection 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;

[0011] Obtain 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;

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

[0013] Generate displacement gradient map: Calculate 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 group 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 relative displacement n ;

[0014] Obtain thermal strain imaging: Convert the displacement gradient map into a strain map, perform visualization processing, and obtain a thermal strain image 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 as follows: 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 outline.

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

[0021] A thermal strain imaging system for implementing any one of the above thermal strain imaging methods, the thermal strain imaging system comprising

[0022] An imaging module, which 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, which heats the detection object to make the detection object reach a preset temperature;

[0024] An analysis module analyzes the ultrasonic image of the detection object before heating and the ultrasonic images at different temperatures after heating to form a 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, used to implement any of the above-mentioned thermal strain imaging methods, comprises a flexible shaft, a transducer base, an imaging transducer, and a heating device. The transducer base is mounted on the end of the flexible shaft, the flexible shaft drives the transducer base to rotate, and the imaging transducer and the heating device are mounted on the transducer base.

[0027] Furthermore, the heating device is a heating transducer array, and the heating transducer array is evenly installed around the periphery of 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 I0 of the detection object before heating, heats the detection object, and collects the ultrasonic images I0 of the detection object when 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, take the first frame of the data before heating I0 as 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; find the typical frames of the end of contraction and diastole of the detected object as the global reference frame i0; find the baseline displacement of each group of data after heating I0 based on the baseline displacement of the feature point n Typical frames i of the detected object at the end of systole and diastole n ; Calculate 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 group 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 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 temperature increase is utilized, and then the echo signals before and after heating are compared and analyzed. The offset of water-containing tissues and lipids in the echo signals is detected, thereby judging the gradient distribution of the change in sound velocity, 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 according to 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 clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall 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 commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] Biological tissues contain large amounts of water, which creates a thermal effect. Furthermore, the acoustic properties of the same tissue vary at different temperatures, and temperature changes can cause changes in the speed of sound propagation within the tissue. The echo displacement gradient generated by the change in sound speed due to temperature increase is called ultrasonic thermal strain. Different tissues experience different thermal strains. For example, muscle tissue contains more water than fat. Therefore, tissue differentiation can be achieved by heating the tissue and imaging and analyzing its thermal strain. The thermal strain imaging method of this application is based on the aforementioned 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 I0 of the test object before heating, heat the test object, and collect the ultrasonic images I0 of the test object when 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 detection 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;

[0041] Obtain 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;

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

[0043] Generate displacement gradient map: Calculate 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 group 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 relative displacement n ;

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

[0045] Specifically, the thermal strain imaging method also includes a detection object positioning step, which precedes the image acquisition step. Specifically, the detection object positioning step involves operating the imaging transducer to acquire an ultrasonic image, and then moving the heating device and the imaging transducer until the ultrasonic image is an image of the detection object. During the movement of the heating device and the imaging transducer, the imaging transducer can operate continuously or at fixed intervals.

[0046] The image acquisition step specifically includes the following steps: when the heating device and imaging transducer are moved toward the test object, the imaging transducer first operates to acquire an ultrasonic image 10 of the test object before heating. Then, the heating device begins operating to heat the test object, and the imaging transducer acquires an ultrasonic image after heating. Specifically, the imaging transducer acquires multiple ultrasonic images after heating, each corresponding to different heating temperatures. In this embodiment, the different heating temperatures are achieved by controlling the heating time. When the heating device is a heating transducer array, the heating transducer array and the imaging transducer operate alternately to prevent interference from the heating transducer array with the imaging transducer. When the heating device is a microwave or other heating structure, the heating device and the imaging transducer can operate simultaneously, i.e., the heating device continuously heats while the imaging transducer operates at preset intervals to acquire ultrasonic images of the test object at different temperatures. When the heating device is a heating transducer array, the imaging transducer acquires the ultrasonic image of the test object using pulsed waves, while the heating transducer array heats the test object using continuous waves. In this embodiment, the pulse wave is a square wave, the operating frequency is 12-60 MHz, and the output voltage is 100 V. The continuous wave is a continuous sine wave, the operating frequency is 1-3.5 MHz, the pulse excitation period is 60-280 ms, the output voltage is 20-60 V, 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 endothelium, vascular adventitia, and plaque outline. Ultrasonic thermal strain is of great value in the detection of vascular diseases. Intravascular plaques are produced due to a variety of factors such as lipid deposition or fibrous tissue proliferation. 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 feature points is 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 Correlation coefficient with the global reference frame i0.

[0049] In the step of obtaining thermal strain imaging, the displacement gradient map is converted into a strain map 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 securely mount the heating device 2 and the imaging transducer 3. During imaging, the flexible shaft drives the transducer base 1 to rotate, thereby achieving annular imaging. The rotation of the flexible shaft is driven by a handle, which contains a rotary motor and encoder.

[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, which is evenly installed on the periphery of the transducer base 1. Figure 3 As shown, the upper surface of the heating transducer array is curved, 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 and distributed in a circular array according to the circumference. The focus of the heating transducer array remains in the same cross section, as shown in FIG. Figure 4 As shown, the cross-section of the tissue is uniformly and fully heated during rotation. When the detection target is a blood vessel, the gray area represents the vessel wall 4. The transducer rotates within the vessel lumen to heat the vessel wall interface and image it. The number of heating transducers arranged in the array can be adjusted based on actual conditions, and their center frequency is within a certain range (e.g., 1-3.5 MHz). The output performance of the heating transducer must meet the human safety threshold.

[0053] The number of imaging transducers 3 can be one or more, and after completing one rotation, an ultrasonic RF signal covering a complete cross section can be obtained. The center frequency of the imaging transducer 3 is selected as appropriate (e.g., a single frequency of 12 MHz, 20 MHz, 40 MHz, 60 MHz, etc., or a dual-center frequency or even multi-center frequency transducer).

[0054] The present application also relates to a thermal strain imaging system for implementing the above 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 an ultrasonic image. 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 this embodiment, the heating module is a heating transducer array. The heating module is responsible for exciting the ultrasonic pulse signal, stimulating the ultrasonic heating transducer to generate a sound beam, and heating the target tissue. Its transmission waveform, operating frequency, pulse excitation period, output voltage, duty cycle, etc. are adjusted as needed. In this 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 a 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 the ultrasonic image before heating I0 and the ultrasonic image data after the nth heating I0 respectively. n The imaging module works in the form of pulse waves, with the transmission and reception of a complete ultrasonic pulse radio frequency signal as one working cycle. 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 I0 of the detection object before heating, heats the detection object, and collects the ultrasonic images I0 of the detection object when 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, take the first frame of the data before heating I0 as 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; find the typical frames of the end of contraction and diastole of the detected object as the global reference frame i0; find the baseline displacement of each group of data after heating I0 based on the baseline displacement of the feature point n Typical frames i of the detected object at the end of systole and diastole n ; Calculate 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 group of heated data is calculated. nThe relative displacement with the global reference frame i0 generates the displacement gradient map G according to the correlation coefficient and 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 temperature increase is utilized, and then the echo signals before and after heating are compared and analyzed. The offset of water-containing tissues and lipids in the echo signals is detected, thereby judging the gradient distribution of the change in sound velocity, distinguishing the tissue composition, and improving the accuracy of tissue and organ detection.

[0060] The above embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patented invention. It should be noted that those skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention. These variations and improvements are equivalent modifications and improvements to the above embodiments based on the essential technology of the present invention and fall within the scope of protection of the present invention.

Claims

1. A thermal strain imaging method, characterized in that: The following steps are involved: Image acquisition: Acquire the ultrasonic image of the test object before heating , heat the test object and collect ultrasonic images when the test object is heated to different temperatures , n is an integer; Extracting baseline displacement of feature points: Based on ultrasonic data before and after heating , select the salient points of the detection object as feature points, and heat the data before The first frame is used 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; Obtain a global reference frame: Find the typical frames of the end-systole and end-diastole of the detected object as the global reference frame ; Get typical frames: Find each set of heated data based on the baseline displacement of the feature points Typical frames of the detected object at end-systole and end-diastole ; Generating displacement gradient maps: Calculating data after heating Typical frame With global reference frame The correlation coefficient between the two is used to calculate the typical frames in each group of heated data. With global reference frame The relative displacement is calculated and the displacement gradient map is generated based on the correlation coefficient and relative displacement. ; Obtain thermal strain imaging: Convert the displacement gradient map into a strain map, perform visualization processing, and obtain a thermal strain image of the cross section of the test object.

2. The thermal strain imaging method according to claim 1, wherein: 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, wherein: The heating transducer array and the imaging transducer work alternately.

4. The thermal strain imaging method according to claim 2, wherein: 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, wherein: The thermal strain imaging method further includes a detection object positioning step, which is located before the image acquisition step. The detection object positioning step specifically comprises: the imaging transducer operates 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, wherein: 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 outline.

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 includes An imaging module, which 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, which heats the detection object to make the detection object reach a preset temperature; An analysis module analyzes the ultrasonic image of the detection object before heating and the ultrasonic images at different temperatures after heating to form a 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 includes 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 periphery of the transducer base.

10. The thermal strain imaging device according to claim 9, characterized in that: The upper surface of the heating transducer array is arc-shaped.

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