A device for detecting intraluminal tissue lesions based on a flexible ultrasonic sensor array and a balloon

Abstract

The application provides a cavity tissue lesion detection device based on a flexible ultrasonic sensor array and a balloon, and belongs to the technical field of medical detection instruments. The device comprises a flexible balloon, a cavity catheter, a layered staggered annular sparse array and a local focusing array. By inflating the balloon, the sensor array is attached to the inner wall, the 16 sensors of the sparse array are distributed in a 360-degree circumferential direction, and the time difference of arrival algorithm is combined to quickly screen and preliminarily locate the lesion; the 4 sensors of the focusing array adopt a compact layout, and the synthetic aperture focusing technology is combined to perform high-resolution depth imaging on the suspicious area. The two different arrays of the application combine the time difference of arrival algorithm and the synthetic aperture focusing technology, realize the accurate dynamic reconstruction of the type and spatial distribution characteristics of the cavity lesion, solve the missed detection risk of the traditional white light endoscope in the screening of the tissue and the narrow field of view of the ultrasonic endoscope, and provide an important quantitative analysis tool for the early identification and treatment of the cavity lesion.

Description

Technical Field

[0001] This invention belongs to the field of medical testing device technology, and relates to a device for detecting intracavitary tissue lesions based on a flexible ultrasound sensor array and a balloon. Background Technology

[0002] Diseases originating from tissues within the human body's cavities are a major global health problem. Assessing the extent of tumor cell invasion into these tissues is crucial for staging intracavitary cancers. Taking the esophagus as an example, subepithelial lesions may not be readily apparent under white light endoscopy, easily leading to misdiagnosis and missed diagnosis. Endoscopic ultrasound (EUS) can clearly show which layer of the esophageal wall the tumor originates from and has invaded, guiding biopsy, malignancy assessment, and treatment planning, thus constituting the "gold standard" for diagnosing this disease.

[0003] However, existing endoscopic ultrasound technology still has the following shortcomings: 1) High cost and stringent implementation conditions: EUS equipment is expensive, operation is complicated, and professional training is required, making it difficult to promote in primary hospitals; 2) Narrow field of view: Traditional ultrasound endoscopy uses mechanical or electronic scanning, which limits the observation range and makes it easy to miss lesions; 3) Artifact interference: Water-bag coupling method is prone to reflection artifacts, which affect imaging quality; 4) Difficulty in achieving rapid screening: Existing technologies are more suitable for detailed examination of known lesions and cannot perform early rapid screening of large-area lumens.

[0004] Therefore, there is an urgent need for a detection system that can perform rapid, non-invasive, and wide-area screening of the inner walls of cavities such as the esophagus and can perform in-depth imaging of suspicious areas. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a cavity tissue lesion detection device based on a flexible ultrasound sensor array and a balloon, which can repeatedly detect the ultrasound feature information of tissue structures in different regions of the cavity, and capture information such as the spatial location, type and degree of invasion of the cavity tissue lesions in real time through corresponding ultrasound information analysis algorithms.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An intracavitary lesion detection device based on a flexible ultrasound sensor array and a balloon is disclosed. The device specifically includes: a flexible balloon; a hollow catheter connected to and fully permeable to the flexible balloon; two flexible ultrasound sensor arrays integrated on the outer surface of the flexible balloon, namely a layered misaligned annular sparse array and a localized focusing array; a data acquisition and preprocessing circuit and a signal transmission circuit connected to the sensor arrays; wherein the layered misaligned annular sparse array is used for rapid screening and preliminary lesion location determination, and the localized focusing array is used for depth scanning of the lesion area.

[0007] Furthermore, the layered staggered ring sparse array contains 16 PVDF flexible ultrasound sensors, which are divided into 4 groups on average, with 4 sensors evenly distributed in each group; the adjacent groups are rotate symmetrically distributed at 22.5°, so that the array as a whole is evenly distributed 360° circumferentially; the local focusing array contains 4 PVDF flexible ultrasound sensors, which adopt a compact layout to form a local high-density array.

[0008] Furthermore, the data acquisition and preprocessing circuit is configured with 20 channels; the sensor array operates at a frequency of 5MHz to 20MHz; and the signal transmission line and ground line in the signal transmission circuit are both located inside the balloon.

[0009] Furthermore, in the data acquisition and preprocessing circuit, the data acquisition process is as follows: After a flexible balloon with an integrated sensor array is placed into the cavity, gas is injected into the balloon through the hollow conduit, so that the flexible sensor array conformally fits the inner wall of the cavity. The layered misaligned ring sparse array is excited by the power excitation module and the electrode gating module to transmit and receive ultrasonic electrical signals, and m frames of raw data are collected to form a 4×4×m signal matrix. After determining the abnormal waveform location based on the signal acquired by the hierarchical misaligned ring sparse array, the local focusing array is excited at the same frequency to acquire n frames of raw data, forming a 1×4×n signal matrix.

[0010] Furthermore, after preprocessing and ADC analog-to-digital conversion of the received signal, the spatial coordinates (xi,yi,zi) and (xj,yj,zj) of sensors i and j are set, and the average sound velocity in the tissue is utilized. The time difference of arrival algorithm is used, as shown in the following formula:

[0011] in( x, y, z () represents the spatial coordinates of the lesion point. The average speed of sound in the organization, Let be the time difference between the signal arriving at the i-th and j-th sensors; assuming the arrival times of the signal from the lesion point to the i-th and j-th sensors are respectively... t i and t j Then its time difference A hyperbola determines the possible location of the lesion; by solving a set of nonlinear equations composed of multiple sensor pairs, the initial spatial coordinates of the lesion can be estimated. Subsequently, the system outputs the sensor data to the signal processing and system control terminal, and transmits the data to the host computer in real time to complete the screening and positioning.

[0012] Furthermore, after screening the lesion location based on data uploaded from the layered misaligned ring sparse array, the balloon is manually adjusted to make the focusing array fit the inner wall of the cavity, and synthetic aperture technology is used for depth detection, as shown in the following formula:

[0013] in For the first The position of each array element The total number of array elements, and the speed of sound in the denominator. Calibration needs to be performed based on the characteristics of the intraballoon medium and tissues, for any focal point in the image. Its signal strength By analyzing the signals received by all array elements m (t) is obtained by delaying and superimposing; then the system outputs the sensor data to the signal processing and system control terminal, and transmits the data to the host computer in real time.

[0014] Furthermore, the received echo signal is amplified and converted from analog to digital at the front end, and then transmitted to the connected host computer or image processing module. This module uses standard ultrasound imaging algorithms to perform beamforming, logarithmic compression, and scan conversion on the digital signal, ultimately reconstructing a tomographic image of the tissue within the cavity and displaying it on the monitor. This completes the early screening of lesions in the tissue within the cavity.

[0015] The beneficial effects of this invention are as follows: This invention acquires real-time ultrasound electrical data of intracavitary tissue lesions using a layered staggered ring sparse array and a local focusing array. Employing a time-of-arrival algorithm and synthetic aperture focusing technology, it achieves precise dynamic reconstruction of the types and spatial distribution characteristics of intracavitary tissue lesions from rapid screening and initial lesion location assessment to in-depth scanning of the lesion area. This solves the problems of missed detection risk in traditional white light endoscopy screening and narrow field of view in ultrasound endoscopy, providing an important quantitative analysis method for the early identification and treatment of intracavitary tissue lesions.

[0016] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a three-dimensional model diagram of the sensor front-end structure of the composite array of the present invention; Figure 2 This is a schematic diagram showing the axial distribution and numbering of the sensors in the composite array; Figure 3 This is a schematic diagram showing the circumferential distribution and numbering of sensors in a composite array; Figure 4 A schematic diagram of the detection process of the front-end device of the present invention within a cavity (taking the esophagus as an example); Figure 5 This is a circuit diagram for composite array signal acquisition and processing. Figure 6 Here is a flowchart of the Time Difference of Arrival (TDOA) algorithm. Figure 7 This is a flowchart of the synthetic aperture focusing technology algorithm. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0019] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0020] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0021] Figure 1 This is a three-dimensional model diagram of the sensor front-end structure of the composite array of the present invention, as shown below. Figure 1 As shown, the balloon body is made of a medical polymer material with good elasticity and liquid barrier properties. By adjusting the balloon inflation pressure, it can form a stable and conformal contact with the inner wall of the cavity after expansion. A total of 20 PVDF flexible sensor arrays in 5 groups are integrated on the outer surface of the flexible balloon in the form of patches. Among them, the 20 sensor arrays of the flexible ultrasound sensor group are numbered, with the layered staggered ring sparse array divided into 4 groups, numbered A, B, C, and D, and the local focusing array group E. Each electrode array is numbered as follows: first layer A1…A4, second layer B1…B4, third layer C1…C4, fourth layer D1…D4, and the fifth group numbered E1…E4. Array groups A to D are arranged in a circumferentially uniform manner, with a 22.5° rotational symmetry between adjacent groups, thus achieving 360° circumferential coverage of the entire lumen without blind spots after balloon expansion, for rapid screening and preliminary localization of suspicious areas in the cavity tissue. Array group E is positioned between groups C and D. Its four internal sensor units are arranged in a compact layout, forming a localized high-density array. This group is dedicated to performing depth scanning and signal extraction on specific suspicious areas after initial localization, to obtain more refined information about the lesion's layers. This design not only ensures that the ultrasound beam is incident on the tube wall tissue at approximately perpendicular angles, reducing echo attenuation and artifacts caused by oblique beam incidence, but also provides stable and consistent acoustic coupling conditions, thereby significantly improving signal stability and diagnostic reliability. All sensor leads are located inside the balloon, ensuring that the leads do not damage the inner wall of the cavity. Figure 2 and Figure 3 The diagram shown is a numbering schematic of the flexible piezoelectric sensor group.

[0022] like Figure 4The diagram illustrates the detection process of the front-end device of this invention within a cavity (taking the esophagus as an example). First, the balloon front-end device is placed inside the human esophageal cavity, and the PVDF flexible ultrasound sensor is attached to its inner wall. Ultrasound waves are emitted through a sparse array to examine the tissue lesions in this area. The received ultrasound electrical signals undergo 16-channel analog signal preprocessing, followed by ADC analog-to-digital conversion. The digital signal is then processed using a time-of-arrival algorithm to achieve rapid screening and initial location determination of lesions. If the waveforms detected by the 16 sensors are not significantly different, the balloon is adjusted to detect other tissues on the esophageal inner wall; otherwise, depth detection and type analysis are performed on each abnormal waveform area. A focused array is used to emit ultrasound waves, and the received ultrasound electrical signals undergo 4-channel analog signal preprocessing. After ADC analog-to-digital conversion, synthetic aperture focusing technology is applied. Then, a standard ultrasound imaging algorithm is used to perform beamforming, logarithmic compression, and scan conversion on the digital signal, ultimately reconstructing a tomographic image of the esophageal inner wall tissue and displaying it on a monitor. If all lesions have been processed, the specific lesion condition is output; otherwise, the detection of the next lesion location continues.

[0023] like Figure 5 The diagram shows a composite array signal acquisition and processing circuit. The overall system framework is based on an MCU. The excitation electrode and the acquisition electrode in the sparse electrode and focused electrode arrays are connected through an electrode selection module. At the same time, the excitation electrode is also driven by the excitation source module, which can select the two sensor arrays according to the actual detection requirements. Under the control of the MCU, the external power supply powers the system. After the signal is processed by the acquisition module, it is uploaded to the host computer through the transmission module to achieve more accurate signal excitation and acquisition functions.

[0024] like Figure 6 The flowchart shown is for the Time Difference of Arrival (TDOA) algorithm. First, a bandpass filter (5MHz-20MHz) is applied to each channel of the sparse array to remove out-of-band noise. Simultaneously, time gain compensation is used to correct the signal amplitude, which decays with depth. One reference channel is selected, and the generalized cross-correlation between the reference channel and the remaining 15 channels is calculated. Phase transform (PHAT) weighting is then used to suppress noise and reverberation.

[0025] in It is the generalized cross-correlation function between channel i and channel j, representing the two signals at different time delays. Similarity under yes Fourier transform, It is receiving signals The conjugate of the Fourier transform, It is a complex exponential term used to implement time-domain translation. This is a frequency variable, measured in Hertz. The arrival time difference between each channel and the reference channel is:

[0026] in Indicates the first The arrival time difference of a channel relative to a reference channel (let's say channel 1). This represents the value of the independent variable that maximizes the function. Then, a positioning solution is performed, establishing a hyperbolic positioning equation system based on the arrival time difference. For any channel pair... :

[0027] Where (x,y,z) represents the location of the lesion target, and (xi,yi,zi) and (xj,yj,zj) represent the spatial coordinates of the i-th and j-th sensor array elements, respectively. This represents the average velocity of ultrasound waves in biological tissues. This refers to the time difference between the signal at the i-th and j-th sensor elements. Typically, multiple channel pairs are selected to form an overdetermined system of equations, which is solved using weighted least squares or Taylor series iterative methods. Let the initial estimation point be... Iterative updates are performed after linearizing each equation:

[0028] in The coefficient matrix, For the residual vector, The weight matrix is ​​used. Iteration continues until convergence to obtain the target position. .

[0029] The echo energy at the location point is compared with the statistical model of normal tissue. If it exceeds the preset threshold, it is marked as a suspicious area, and its azimuth and depth range are recorded to trigger the next stage of focused array imaging.

[0030] like Figure 7 The diagram shows the flowchart of the synthetic aperture focusing (SAP) technology algorithm. In lesion detection using the focusing array, the array is controlled to emit pulses sequentially. This can be achieved by emitting pulses simultaneously from all array elements or by emitting pulses sequentially from individual elements, while simultaneously receiving echo signals from four channels. The original signal is then subjected to low-noise amplification, anti-aliasing filtering, and high-precision analog-to-digital conversion to ensure signal fidelity.

[0031] Divide the region of interest into uniform grid points. The grid spacing is usually set to... , The center frequency.

[0032] Calculate the two-way propagation delay for each grid point r and each array element m. If all array elements are transmitted simultaneously, then:

[0033] in This refers to the ultrasonic wave emitted from the m-th element and reaching the focal point. The two-way propagation time required for the image to be reflected back to the same array element. Indicates the focal point With the array element The Euclidean distance between them This represents the average propagation speed of ultrasound waves in tissue. If synthetic aperture mode is used, i.e., only one element transmits at a time, and all elements receive, then for the transmitting element t and the receiving element m:

[0034] in This indicates that the ultrasonic wave is emitted from the transmitting element t, passes through the focal point... After reflection, the two-way propagation time received by the receiving element m. For single-transmission mode, the image intensity at the focal point r is the coherent superposition of the delayed signals from each channel:

[0035] in As the focus The intensity of the envelope image, The apodization weighting coefficients for the m-th array element are used to suppress sidelobes. This refers to the raw RF echo signal acquired by the m-th receiving channel. If synthetic aperture mode is used, all transmit-receive combinations need to be accumulated:

[0036] in The focal point reconstructed using the synthetic aperture model Image intensity, It is the echo transmitted by the t-th array element and received by the m-th array element.

[0037] Envelope extraction is then performed, and the envelope image is obtained by taking the modulus of the superimposed complex signal. If the radio frequency signal is used directly, a Hilbert transform is required to obtain the analytic signal. The dynamic range is then mapped to the grayscale display range.

[0038] in This represents the grayscale value of the image after logarithmic compression. It is the maximum value of the envelope intensity in the entire image, used for normalization, and a very small positive number is introduced in the formula. This is used to prevent taking the logarithm of zero. Medium-range filtering or anisotropic diffusion filtering is applied to suppress speckle noise and preserve tissue boundaries.

[0039] In the reconstructed image, the lesion area is automatically or semi-automatically segmented based on features such as grayscale, texture, and morphology. Combined with the prior location provided by the time difference of arrival algorithm, the size of the lesion, the clarity of its boundary, and the echo intensity are accurately measured, and it is determined which layer of the cavity wall it is located in. Finally, the comprehensive diagnostic information is output through the host computer.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A device for detecting intracavitary tissue lesions based on a flexible ultrasound sensor array and a balloon, characterized in that, The detection device specifically includes: Flexible balloon; A hollow catheter connected to the flexible balloon and with its entire length traversed; Two flexible ultrasound sensor arrays are integrated on the outer surface of the flexible balloon, namely a layered misaligned ring sparse array and a local focusing array; The data acquisition and preprocessing circuit, and the signal transmission circuit, are connected to the sensor array. The layered misaligned annular sparse array is used for rapid screening and preliminary determination of lesion location, while the local focusing array is used for deep scanning of the lesion area.

2. The intracavitary tissue lesion detection device based on a flexible ultrasound sensor array and a balloon according to claim 1, characterized in that, The layered staggered ring sparse array contains 16 PVDF flexible ultrasound sensors, which are divided into 4 groups on average, with 4 sensors evenly distributed in each group; the adjacent groups are rotate symmetrically distributed at 22.5°, so that the array as a whole is evenly distributed 360° circumferentially; the local focusing array contains 4 PVDF flexible ultrasound sensors, which are arranged in a compact layout to form a local high-density array.

3. The intracavitary tissue lesion detection device based on a flexible ultrasound sensor array and a balloon according to claim 2, characterized in that, The data acquisition and preprocessing circuit is configured with 20 channels; the sensor array operates at a frequency of 5MHz to 20MHz; and the signal transmission line and ground line in the signal transmission circuit are both located inside the balloon.

4. The intracavitary tissue lesion detection device based on a flexible ultrasound sensor array and a balloon according to claim 3, characterized in that, In the data acquisition and preprocessing circuit, the data acquisition process is as follows: After a flexible balloon with an integrated sensor array is placed into the cavity, gas is injected into the balloon through the hollow conduit, so that the flexible sensor array conformally fits the inner wall of the cavity. The layered misaligned ring sparse array is excited by the power excitation module and the electrode gating module to transmit and receive ultrasonic electrical signals, and m frames of raw data are collected to form a 4×4×m signal matrix. After determining the abnormal waveform location based on the signal acquired by the hierarchical misaligned ring sparse array, the local focusing array is excited at the same frequency to acquire n frames of raw data, forming a 1×4×n signal matrix.

5. The intracavitary tissue lesion detection device based on a flexible ultrasound sensor array and a balloon according to claim 4, characterized in that, After preprocessing and ADC analog-to-digital conversion of the received signal, the spatial coordinates (xi,yi,zi) and (xj,yj,zj) of sensors i and j are set, and the average speed of sound in the tissue is utilized. The time difference of arrival algorithm is used, as shown in the following formula: in( x,y,z () represents the spatial coordinates of the lesion point. The average speed of sound in the organization, Let be the time difference between the signal arriving at the i-th and j-th sensors; assuming the arrival times of the signal from the lesion point to the i-th and j-th sensors are respectively... t i and t j Then its time difference A hyperbola that determines the possible location of the lesion; By solving the nonlinear equations formed by multiple sensor pairs, the initial spatial coordinates of the lesion can be estimated. The system then outputs the sensor data to the signal processing and system control terminal, and transmits the data to the host computer in real time to complete the screening and positioning.

6. The intracavitary tissue lesion detection device based on a flexible ultrasound sensor array and a balloon according to claim 5, characterized in that, After screening the lesion location based on data uploaded by the layered misaligned ring sparse array, the balloon is manually adjusted to make the focusing array fit the inner wall of the cavity, and synthetic aperture technology is used for depth detection, as shown in the following formula: in For the first The position of each array element The total number of array elements, and the speed of sound in the denominator. Calibration needs to be performed based on the characteristics of the intraballoon medium and tissues, for any focal point in the image. Its signal strength By analyzing the signals received by all array elements m (t) is obtained by delaying and superimposing; The system then outputs the sensor data to the signal processing and system control terminal, transmitting the data to the host computer in real time.

7. The intracavitary tissue lesion detection device based on a flexible ultrasound sensor array and a balloon according to claim 6, characterized in that, The received echo signal is amplified and converted from analog to digital at the front end, then transmitted to a connected host computer or image processing module. This module uses standard ultrasound imaging algorithms to perform beamforming, logarithmic compression, and scan conversion on the digital signal, ultimately reconstructing a tomographic image of the tissue within the cavity and displaying it on a monitor. This completes the early screening of lesions in the tissue within the cavity.

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