Arthroscopic apparatus with integrated optical-photoacoustic multi-modal imaging, and imaging method therefor

Abstract

An arthroscopic apparatus with integrated optical-photoacoustic multi-modal imaging, and an imaging method therefor. The arthroscopic apparatus comprises a light source and optical path system (2), a control and data collection system (1), and an arthroscopic probe (14). The imaging method therefor comprises the following steps: pulsed excitation light passing through a focus-adjustable collimator and entering an arthroscopic probe (14) via an optical path system; by means of a combination of a hollow servo electric motor (22) and a λ / 2 sheet (23), realizing the modulation of polarized light; by means of a dichroic mirror (24), realizing a common path of pulsed light of different wavelengths; by means of a beam splitter (19), realizing a common path of white light and pulsed light; using a MEMS mirror (20) to realize rapid scanning of tissue by the pulsed light; a micro-transducer (31) collecting an echo signal; a computer (17) completing image reconstruction for photoacoustic, photoacoustic polarization and photoacoustic elasticity imaging; and a charge-coupled device (18) of the arthroscopic probe (14) collecting an optical signal for optical image reconstruction. The present invention realizes optical, photoacoustic, photoacoustic polarization and photoacoustic elasticity imaging by means of the integrated arthroscopic probe (14), and can be used for microvascular assessment within a joint cavity, and the assessment of anisotropy and biomechanical properties of cartilage and ligaments.

Description

An arthroscopic device and imaging method integrating optical-photoacoustic multimodal imaging Technical Field

[0001] This invention belongs to the field of arthroscopic imaging, and specifically relates to an arthroscopic device and its imaging method that integrates optical-photoacoustic multimodal imaging. Background Technology

[0002] Osteoarthritis (OA) is the most prevalent joint disease in the world today, affecting millions of people worldwide. This disease causes abnormal remodeling of normal joint structures, leading to joint degeneration, a condition affecting approximately 10-12% of the adult population globally. Osteoarthritis (OA) can cause permanent joint damage, resulting in chronic pain, reduced range of motion, and significantly lower quality of life, leading to an increased socioeconomic burden.

[0003] For osteoarthritis (OA), timely prediction of joint structure progression and disease is crucial, and appropriate treatment measures are very important. Timely diagnosis and treatment can improve quality of life and reduce early mortality. Furthermore, with the implementation of aggressive targeted treatment strategies, OA symptoms can often be significantly improved, so it is necessary to monitor the progress of treatment frequently.

[0004] Although the clinical diagnostic criteria for osteoarthritis (OA) do not include imaging evidence, plain X-ray films are frequently used clinically to assess the progression of OA, but their imaging capabilities for cartilage and synovium are poor. Computed tomography (CT) has strong imaging capabilities for bone structures, but it is expensive and involves ionizing radiation. Ultrasound can sensitively identify changes in soft tissues and superficial bones and has the advantage of non-invasive vascular assessment, but it has poor penetration into deep intra-articular structures. Magnetic resonance imaging (MRI) provides more information than the above methods, does not involve ionizing radiation, and has excellent anatomical resolution, but the examination time is long, and it may not be available for certain patients.

[0005] Arthroscopy is a minimally invasive diagnostic and treatment method primarily used for the observation and treatment of diseases inside joints. By inserting a thin tube (arthoscope) into the joint, doctors can directly observe the internal structures, such as cartilage, tendons, and ligaments. This technique is widely used for the examination and treatment of joints such as the knee, shoulder, ankle, and elbow.

[0006] Traditional arthroscopic techniques primarily rely on white light optical imaging systems. While these systems can provide intuitive images of the joint interior, they have limitations in terms of resolution and contrast. Especially when identifying early pathological changes (such as minor soft tissue injuries), white light imaging often fails to provide sufficient detail.

[0007] Photoacoustic imaging is an emerging biomedical imaging technology that combines optical and acoustic principles. It uses laser light to irradiate tissue, and then relies on the ultrasound signals generated after the tissue absorbs the laser light to construct an image that reflects the distribution of differences in light absorption within the tissue. Photoacoustic imaging can obtain images of the distribution of blood vessels within the joint cavity, which can be used to assess the progression of osteoarthritis.

[0008] Polarized photoacoustic imaging technology, based on photoacoustic imaging, analyzes the intensity of tissue absorption of polarized light vectors at different angles, enabling the identification of anisotropic changes in tissues such as cartilage and ligaments.

[0009] Photoacoustic elastography, based on photoacoustic imaging, measures elastic parameters by utilizing the time and phase characteristics of the photoacoustic point source response through thermoelastic expansion and damping effects. It can identify changes in the mechanical properties of tissues such as cartilage and ligaments.

[0010] Currently, commonly used arthroscopy is white light arthroscopy, which mainly relies on white light optical imaging. Traditional white light imaging technology primarily provides morphological information about tissues, but cannot provide direct information on the biochemical and molecular properties of tissues. This limitation is determined by the working principle of white light imaging technology. It mainly relies on the reflection and refraction of light to form images, and these processes do not involve the detection of changes in the biochemical composition or molecular structure of tissues. Therefore, an arthroscopic device integrating optical-photoacoustic multimodal imaging is invented. In this device, photoacoustic imaging technology combines the high resolution of optical imaging with the deep depth of acoustic imaging, enabling the imaging of intra-articular vascular distribution to assess the progression of osteoarthritis. Furthermore, based on photoacoustic imaging, polarized photoacoustics and photoacoustic elastography are integrated to characterize the anisotropy and biomechanical differences of intra-articular cartilage, ligaments, and other structures, which can be used for early diagnosis of osteoarthritis and pre- and post-operative imaging assessment.

[0011] The patent, numbered 202010263211.X and titled "Multimodal Microscopic Endoscopic Imaging Device and Method," discloses a multimodal microscopic endoscopic imaging device that combines confocal, photoacoustic, and ultrasound imaging methods, and simultaneously possesses both forward and lateral scanning modes. However, it lacks polarized photoacoustic and photoacoustic elastic imaging modes, and thus lacks the ability to identify pathological changes in major intra-articular tissues such as cartilage and ligaments.

[0012] The invention patent with patent number 202111573589.0, entitled "A High-Definition Ultra-Wide-Angle Arthroscopic Imaging System," introduces a high-definition ultra-wide-angle arthroscopic imaging system with high resolution, a large field of view, and low distortion. While traditional optical arthroscopes improve joint resolution and viewing angle, they still suffer from drawbacks, only able to extract changes in tissue surface morphology and unable to image pathological changes at the tissue level. Summary of the Invention

[0013] The purpose of this invention is to overcome the shortcomings of the existing technology by providing an arthroscopic device that integrates optical-photoacoustic multimodal imaging. This device can realize imaging in four modes: optical, photoacoustic, polarized photoacoustic, and photoacoustic elastography. It can perform optical imaging on the target area to obtain morphological information of the tissue surface, and simultaneously perform photoacoustic imaging to obtain images of blood vessel distribution in the joint cavity. Polarized photoacoustic and photoacoustic elastography can characterize the anisotropy and biomechanical differences of structures such as cartilage and ligaments in the joint cavity. It can be used for early diagnosis of osteoarthritis and preoperative and postoperative imaging evaluation, providing a multi-parameter data detection device and method for the field of medical imaging.

[0014] To achieve the above objectives, the present invention adopts the following technical solution:

[0015] An arthroscopic device integrating optical-photoacoustic multimodal imaging, the arthroscope including a control and data acquisition system, a light source and optical path system, and an arthroscopic probe.

[0016] The control and data acquisition system includes an FPGA development board, a signal amplifier, a data acquisition card, and a computer. The FPGA development board acts as the control module, responsible for generating timing pulses to control the coordinated operation of various systems. After the pulsed laser is incident on the tissue surface, the tissue surface is stimulated to generate ultrasonic waves, which are received by a miniature transducer in the arthroscopic probe. The signal is amplified by the signal amplifier and then enters the data acquisition card, which finally transmits the raw data to the computer.

[0017] The light source and optical path system includes a pulsed laser, a first fiber coupler, a single-mode fiber, a first adjustable-focus collimator, a second fiber coupler, a polarization-maintaining fiber, a second adjustable-focus collimator, and a white light source. The control terminals of the white light source and the pulsed laser are connected to the FPGA of the control and data acquisition system to control the light source output. Pulsed lasers with wavelengths of 532nm and 1550nm are respectively connected to the optical path system through the first and second fiber couplers, and then pass through the single-mode fiber and the polarization-maintaining fiber, before entering the arthroscopic probe through the first and second adjustable-focus collimators.

[0018] The arthroscopic probe includes a charge-coupled device (CCD), a beam splitter, a MEMS mirror, a pulsed fiber optic interface, a hollow servo motor, a λ / 2 plate, a dichroic filter, a focusing lens, a cold light source interface, a rod lens assembly, an arthroscopic housing, a lens group, a transmissive acoustic mirror, a miniature transducer, and a light-guiding fiber. A 532nm pulsed laser enters the arthroscopic probe through the pulsed fiber optic interface, is incident perpendicularly, and passes through the dichroic mirror. A 1550nm pulsed laser enters the arthroscopic probe through the pulsed fiber optic interface, passes through the hollow servo motor and the λ / 2 plate. The rotation of the hollow servo motor modulates the polarized light. The 1550nm pulsed laser, after being reflected by the dichroic mirror, is combined with the 532nm pulsed laser. The combined beam is incident on the surface of the MEMS mirror, reflected, and then focused by the focusing lens. After passing through the beam splitter, it enters the rod lens assembly, propagates within the rod lens, passes through the lens group and the transmissive acoustic mirror, and finally enters the tissue surface. A white light source illuminates the tissue through a light-guiding fiber on the sidewall of the arthroscopic probe. The optical signal is reflected by a beam splitter and received by a charge-coupled device (CCD). As a preferred embodiment, the effective focal length of the first adjustable-focus collimator is 7.5 mm, and the wavelength range of the antireflective coating is 350 nm-700 nm. The effective focal length of the second adjustable-focus collimator is also 7.5 mm, and the wavelength range of the antireflective coating is 1050 nm-1700 nm. The addition of the first and second adjustable-focus collimators achieves confocal focusing of lasers with different wavelengths.

[0019] As a preferred technical solution, the hollow servo motor has an inner diameter of 4mm and a speed range of 0.5-2000rpm. The addition of the hollow servo motor enables the rotation of the λ / 2 plate, thereby changing the polarization state of the light.

[0020] As a preferred technical solution, the cutoff wavelength of the short-pass dichroic mirror is 950nm, the transmittance of 532nm wavelength laser is 85-95%, and the reflectance of 1550nm wavelength laser is 90-99%. The addition of the dichroic mirror enables the co-pathing of pulsed light of different wavelengths.

[0021] As a preferred technical solution, the beam splitter has a white light transmittance of 50%, a 532nm wavelength laser reflectance of 50%, and a 1550nm wavelength laser reflectance of 80-90%. The addition of the beam splitter enables white light and laser to share the same path.

[0022] As a preferred technical solution, the MEMS mirror has a scanning angle of 5-20° and a response frequency of 2.5-5KHz. The scanning range and scanning speed can be changed by changing the frequency of the driving signal. The addition of the MEMS mirror can realize rapid scanning of the imaging area.

[0023] As a preferred technical solution, the pulsed laser is one of a semiconductor laser, a solid-state laser, a dye laser, or a gas laser, and the output pulsed laser wavelength range is 400nm to 2000nm, and the pulse width is 3ns to 30ns.

[0024] As a preferred technical solution, the signal amplifier has an amplification gain of 50dB to 60dB.

[0025] Another object of the present invention is to provide a method for imaging using the above-described imaging device, which can obtain white light images, photoacoustic images, polarized photoacoustic images, and photoacoustic elastic images of the imaging area.

[0026] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0027] The present invention utilizes a method for an arthroscopic device integrating optical-photoacoustic multimodal imaging, comprising the following steps:

[0028] a. System Trigger: The control and data acquisition system generates a trigger signal to control the 532nm and 1550nm wavelength pulsed lasers to generate pulsed light, and simultaneously controls the illumination source. The pulsed lasers of different wavelengths enter the fiber coupler, and then enter the arthroscopic probe through the first and second adjustable focusing collimators. The 1550nm wavelength laser is modulated by the electro-optic polarization modulator and then combined with the 532nm wavelength laser through the dichroic mirror. The combined light passes through the focusing lens and the beam splitter and finally reaches the surface of the tissue to be imaged. The illumination light illuminates the surface of the tissue to be imaged through the optical fiber.

[0029] b. Data acquisition: The photoacoustic signal excited by the pulsed laser is reflected by the light-transmitting mirror and received by the ultrasonic transducer on the side wall of the arthroscope. It is then converted into an electrical signal and enters the signal amplifier through the coaxial cable. The amplified electrical signal is acquired by the acquisition card and sent to the computer. The optical signal passes through the rod lens group and enters the charge-coupled device through the beam splitter. The charge-coupled device converts the incident light signal into a charge output and enters the computer through the data line.

[0030] c. Image Processing: The computer uses the acquired data for the reconstruction of optical, photoacoustic, polarized photoacoustic, and photoacoustic elastic images. Photoacoustic image reconstruction: Utilizing the absorption of 532nm wavelength laser by hemoglobin, the ultrasonic waves (photoacoustic signal) generated by instantaneous thermal expansion are used to reconstruct the maximum projection image of the blood vessel through a maximum projection algorithm. Photoacoustic polarized image reconstruction: By using a hollow servo motor and a λ / 2 plate combined with different polarized laser states, the anisotropic absorption differences of the tissue sample are obtained, thereby reconstructing a quantitative anisotropic image of the tissue sample. Photoacoustic elastic image reconstruction: By measuring the time required for the vibration displacement of the tissue sample surface to rise from zero to its maximum value, the elastic modulus of the tissue sample can be calculated, and its quantitative elastic image can be reconstructed.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. This invention realizes an arthroscopic device and its imaging method that integrates optical-photoacoustic multimodal imaging, enabling real-time high-resolution multi-parameter imaging to obtain white light images, photoacoustic images, polarized photoacoustic images, and photoacoustic-elastographic images of the imaging area. Among these, photoacoustic imaging technology combines the high resolution of optical imaging with the deep depth of acoustic imaging, enabling the imaging of intra-articular vascular distribution images for assessing the progression of osteoarthritis. Furthermore, by integrating polarized photoacoustic and photoacoustic-elastographic imaging, it can characterize the anisotropy and biomechanical differences of intra-articular cartilage, ligaments, and other structures, and can be used for early diagnosis of osteoarthritis and pre- and post-operative imaging evaluation.

[0033] 2. This invention achieves a confocal shared optical path for 532nm and 1550nm wavelength lasers. By adding an adjustable-focus collimator, these two wavelengths of laser light can be confocal. The addition of a dichroic mirror allows the 532nm and 1550nm wavelength lasers to share the same optical path. Due to the significant wavelength difference between these two lasers, appropriately selecting a dichroic mirror with a suitable cutoff frequency can effectively achieve beam combining of the two wavelengths of laser light.

[0034] 3. This invention employs a MEMS mirror to achieve rapid scanning of photoacoustic signals, significantly improving the system's flexibility and operability compared to traditional motor scanning methods. The miniaturized design of the MEMS mirror makes the arthroscope more flexible in operation, enabling precise control of the laser emission direction, thereby improving image clarity and contrast. This characteristic helps to accelerate data acquisition speed and achieve real-time imaging of photoacoustic multimodal signals.

[0035] 4. This invention achieves efficient modulation of polarized light by combining a hollow servo motor with a λ / 2 plate. By controlling the rotation of the hollow servo motor through the FPGA in the control system, the rotation angle of the λ / 2 plate can be precisely adjusted, thereby more effectively manipulating the polarization state of light and improving the quality of polarized light acoustic imaging.

[0036] 5. The internal lens structure design of the arthroscopic probe of this invention allows for adjustment of the device diameter to accommodate joints at different locations. The working distance of the multimodal imaging system can be changed by adjusting the focal point position of the photoacoustic system. Furthermore, adjusting the number of lens groups can also change the system's working distance, thereby meeting the needs for multimodal imaging at different joint depths and conforming to the requirements of practical clinical applications. Attached Figure Description

[0037] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments:

[0038] Figure 1 is a schematic diagram of an arthroscopic device that integrates optical-photoacoustic multimodal imaging.

[0039] Figure 2 is a schematic diagram of an arthroscopic imaging device that integrates optical-photoacoustic multimodal imaging.

[0040] Figure 3 is a schematic diagram of the probe structure of an arthroscopic device that integrates optical-photoacoustic multimodal imaging.

[0041] Explanation of reference numerals: 1. Control and data acquisition system; 2. Light source and optical path system; 3. Arthroscopy lens; 4. Tissue surface; 5. FPGA; 6. Pulsed laser; 7. First fiber optic coupler; 8. Single-mode fiber; 9. First adjustable collimator; 10. Second fiber optic coupler; 11. Polarization-maintaining fiber; 12. Second adjustable collimator; 13. White light source; 14. Arthroscopy probe; 15. Signal amplifier; 16. Acquisition card; 17. Computer; 18. Charge-coupled device; 19. Beam splitter; 20. MEMS mirror; 21. Pulsed fiber optic interface; 22. Hollow servo motor; 23. λ / 2 plate; 24. Dichroic filter; 25. Focusing lens; 26. Cold light source entrance; 27. Rod lens assembly; 28. Arthroscopy housing; 29. ​​Lens assembly; 30. Transmitting acoustic mirror; 31. Miniature transducer; 32. Light guide fiber. Detailed Implementation

[0042] The present invention will be further described below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited to these embodiments.

[0043] As shown in Figure 2, this embodiment discloses an arthroscopic device and its imaging method that integrates optical-photoacoustic multimodal imaging, including a control and data acquisition system, a light source and optical path system, and an arthroscopic probe.

[0044] The control and data acquisition system 1 includes an FPGA development board 5, a signal amplifier 15, a data acquisition card 16, and a computer 17. The FPGA development board 5 serves as the control module, responsible for generating timing pulses to control the coordinated operation of various systems. After the pulsed laser is incident on the tissue surface 4, the tissue surface is stimulated to generate ultrasonic waves, which are received by the miniature transducer 31 in the arthroscopic probe. The signal is amplified by the signal amplifier 15 and then enters the data acquisition card 16, which finally transmits the raw data to the computer 17.

[0045] Furthermore, the light source and optical path system 2 includes a pulsed laser 6, a first fiber coupler 7, a single-mode fiber 8, a first adjustable-focus collimator 9, a second fiber coupler 10, a polarization-maintaining fiber 11, a second adjustable-focus collimator 12, and a white light source 13. The control terminals of the white light source 13 and the pulsed laser 6 are connected to the FPGA 5 of the control and data acquisition system to control the light source output. Pulsed lasers with wavelengths of 532nm and 1550nm are respectively connected to the optical path system through the first fiber coupler 7 and the second fiber coupler 10, and then enter the arthroscopic probe 3 through the single-mode fiber 8 and the polarization-maintaining fiber 11, and after passing through the first adjustable-focus collimator 9 and the second adjustable-focus collimator 12.

[0046] Furthermore, the arthroscopic probe 3 includes a charge-coupled device (CCD) element 18, a beam splitter 19, a MEMS mirror 20, a pulsed fiber optic interface 21, a hollow servo motor 22, a λ / 2 plate 23, a dichroic filter 24, a focusing lens 25, a cold light source interface 26, a rod lens assembly 27, an arthroscopic housing 28, a lens assembly 29, a light-transmitting reflector 30, a miniature transducer 31, and a light-guiding fiber 32. A 532nm pulsed laser enters the arthroscopic probe through the pulsed fiber optic interface 21, is perpendicularly incident, and passes through the dichroic filter 24. A 1550nm pulsed laser enters the arthroscopic probe through the pulsed fiber optic interface 21, and passes through the hollow servo motor 22 and the λ / 2 plate 23. The rotation of the hollow servo motor achieves modulation of the polarized light. A 1550nm pulsed laser beam is reflected by a dichroic mirror 24 and then combined with a 532nm pulsed laser beam. The combined beam is incident on the surface of the MEMS mirror 20. After reflection, the scanning light is focused by a focusing lens 25, passes through a beam splitter 19, and then enters the rod lens group 29. It is transmitted inside the rod lens, passes through the lens group 27 and the light-transmitting reflector 30, and finally enters the tissue surface. The white light source 13 illuminates the tissue through the light-guiding fiber 32 on the side wall of the arthroscopic probe. The optical signal is reflected by a beam splitter 28 and received by a charge-coupled device 18.

[0047] In this embodiment, the effective focal length of the first adjustable collimator is 7.5mm, and the wavelength range of the antireflection coating is 350nm-700nm. The effective focal length of the second adjustable collimator is 7.5mm, and the wavelength range of the antireflection coating is 1050nm-1700nm. The addition of the first and second adjustable collimators enables confocal lasers of different wavelengths.

[0048] In this implementation case, a hollow servo motor with an inner diameter of 4mm and a speed range of 1000rpm is used to rotate the λ / 2 plate, thereby changing the polarization state of the light.

[0049] In this implementation, the cutoff wavelength of the short-pass dichroic mirror is 950nm, the transmittance of 532nm wavelength laser is 85-95%, and the reflectance of 1550nm wavelength laser is 95%. The addition of the dichroic mirror enables the co-pathing of pulsed light of different wavelengths.

[0050] In this implementation, the beam splitter has a white light transmittance of 50%, a 532nm wavelength laser reflectivity of 50%, and a 1550nm wavelength laser reflectivity of 85%. The addition of the beam splitter enables white light and laser to share the same path.

[0051] In this implementation example, the MEMS mirror has a scanning angle of 10° and a response frequency of 2.5KHz. The scanning range and scanning speed can be changed by altering the frequency of the driving signal. The addition of the MEMS mirror enables rapid scanning of the imaging area.

[0052] In this implementation example, the pulsed laser is a semiconductor laser, and the output pulsed laser wavelengths are 532nm and 1550nm, respectively, with a pulse width of 10ns.

[0053] In this implementation example, the signal amplifier gain is 60dB.

[0054] In this implementation case, the arthroscope shell is a high-temperature and high-pressure sterilization resistant, biocompatible metal shell, the working distance is 10cm, and the diameter of the arthroscope lens is 4mm.

[0055] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0056] The present invention utilizes a method for an arthroscopic device integrating optical-photoacoustic multimodal imaging, comprising the following steps:

[0057] a. System Trigger: The control and data acquisition system generates a trigger signal to control the 532nm and 1550nm wavelength pulsed lasers to generate pulsed light, and simultaneously controls the illumination source. The pulsed lasers of different wavelengths enter the fiber coupler, and then enter the arthroscopic probe through the first and second adjustable focusing collimators. The 1550nm wavelength laser is modulated by the electro-optic polarization modulator and then combined with the 532nm wavelength laser through the dichroic mirror. The combined light passes through the focusing lens and the beam splitter and finally reaches the surface of the tissue to be imaged. The illumination light illuminates the surface of the tissue to be imaged through the optical fiber.

[0058] b. Data acquisition: The photoacoustic signal excited by the pulsed laser is reflected by the light-transmitting mirror and received by the ultrasonic transducer on the side wall of the arthroscope. It is then converted into an electrical signal and enters the signal amplifier through the coaxial cable. The amplified electrical signal is acquired by the acquisition card and sent to the computer. The optical signal passes through the rod lens group and enters the charge-coupled device through the beam splitter. The charge-coupled device converts the incident light signal into a charge output and enters the computer through the data line.

[0059] c. Image Processing: The computer uses the acquired data for the reconstruction of optical, photoacoustic, polarized photoacoustic, and photoacoustic elastic images. Photoacoustic image reconstruction: Utilizing the absorption of 532nm wavelength laser by hemoglobin, the ultrasonic waves (photoacoustic signal) generated by instantaneous thermal expansion are used to reconstruct the maximum projection image of the blood vessel through a maximum projection algorithm. Photoacoustic polarized image reconstruction: By using a hollow servo motor and a λ / 2 plate combined with different polarized laser states, the anisotropic absorption differences of the tissue sample are obtained, thereby reconstructing a quantitative anisotropic image of the tissue sample. Photoacoustic elastic image reconstruction: By measuring the time required for the vibration displacement of the tissue sample surface to rise from zero to its maximum value, the elastic modulus of the tissue sample can be calculated, and its quantitative elastic image can be reconstructed.

[0060] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. An arthroscopic device integrating optical-photoacoustic multimodal imaging, the arthroscopy comprising a control and data acquisition system, a light source and optical path system, and an arthroscopic probe; The control and data acquisition system includes an FPGA development board, a signal amplifier, a data acquisition card, and a computer. The FPGA development board, as the control module, is responsible for generating timing pulses to control the coordinated operation of various systems. After the pulsed laser is incident on the tissue surface, the tissue surface is stimulated to generate ultrasonic waves. These ultrasonic waves are received by the miniature transducer in the arthroscopic probe. After the signal is amplified by the signal amplifier, the signal enters the data acquisition card, and finally the data acquisition card transmits the raw data to the computer. The light source and optical path system includes a pulsed laser, a first fiber coupler, a single-mode fiber, a first adjustable-focus collimator, a second fiber coupler, a polarization-maintaining fiber, a second adjustable-focus collimator, and a white light source. The control terminals of the white light source and the pulsed laser are connected to the FPGA of the control and data acquisition system to control the output of pulsed lasers with wavelengths of 532nm and 1550nm. These pulsed lasers are then connected to the optical path system through the first and second fiber couplers, respectively, and subsequently pass through the single-mode fiber and the polarization-maintaining fiber, and then through the first and second adjustable-focus collimators to enter the arthroscopic probe. The arthroscopic probe includes a charge-coupled device (CCD), a beam splitter, a MEMS mirror, a pulsed fiber optic interface, a hollow servo motor, a λ / 2 plate, a dichroic filter, a focusing lens, a cold light source interface, a rod lens assembly, an arthroscopic housing, a lens assembly, a transmissive acoustic mirror, a miniature transducer, and a light-guiding fiber. A 532nm pulsed laser enters the arthroscopic probe through the pulsed fiber optic interface, is perpendicularly incident, and passes through the dichroic filter. A 1550nm pulsed laser enters the arthroscopic probe through the pulsed fiber optic interface, passes through the hollow servo motor and the λ / 2 plate. The rotation of the hollow servo motor modulates the polarized light. The 1550nm pulsed laser is reflected by the dichroic filter and then combined with the 532nm pulsed laser. The combined light is incident on the surface of the MEMS mirror, reflected, and then focused by the focusing lens. After passing through the beam splitter, it enters the rod lens assembly, is transmitted inside the rod lens, passes through the lens assembly and the transmissive acoustic mirror, and finally enters the tissue surface. A white light source illuminates the tissue through the light-guiding fiber on the side wall of the arthroscopic probe. The optical signal is received by the CCCD after being reflected by the beam splitter.

2. The arthroscopic device for integrated optical-photoacoustic multimodality imaging according to claim 1, wherein, The effective focal length of the first adjustable collimator is 7.5mm, and the wavelength range of the antireflective coating is 350nm-700nm. The effective focal length of the second adjustable collimator is 7.5mm, and the wavelength range of the antireflective coating is 1050nm-1700nm. The addition of the first and second adjustable collimators enables confocal lasers of different wavelengths.

3. The arthroscopic device for integrated optical-photoacoustic multimodality imaging according to claim 1, wherein, The hollow servo motor has an inner diameter of 4mm and a speed range of 0.5-2000rpm. The addition of the hollow servo motor enables the rotation of the λ / 2 plate, thereby changing the polarization state of the light.

4. The arthroscopic device for integrated optical-photoacoustic multimodality imaging according to claim 1, wherein, The dichroic mirror has a cutoff wavelength of 950nm, a transmittance of 85-95% for 532nm wavelength laser, and a reflectance of 90-99% for 1550nm wavelength laser. The addition of the dichroic mirror enables the co-pathing of pulsed light of different wavelengths.

5. The arthroscopic device integrating optical-photoacoustic multimodality imaging according to claim 1, wherein, The beam splitter has a white light transmittance of 50%, a 532nm wavelength laser reflectance of 50%, and a 1550nm wavelength laser reflectance of 80-90%. The addition of the beam splitter enables white light and laser to share the same path.

6. The arthroscopic device integrating optical-photoacoustic multimodality imaging according to claim 1, wherein, The MEMS mirror has a scanning angle of 5-20° and a response frequency of 2.5-5KHz. The scanning range and scanning speed can be changed by changing the frequency of the driving signal. The addition of the MEMS mirror enables rapid scanning of the imaging area.

7. The arthroscopic device integrating optical-photoacoustic multimodality imaging according to claim 1, wherein, The pulsed laser is one of a semiconductor laser, a solid-state laser, a dye laser, or a gas laser, and the output pulsed laser wavelength range is 400nm to 2000nm, with a pulse width of 3ns to 30ns.

8. The arthroscopic device integrating optical-photoacoustic multimodality imaging according to claim 1, wherein, The signal amplifier has an amplification gain of 50dB to 60dB.

9. An imaging method using the optical- photoacoustic multimodality imaging arthroscopic device according to any one of claims 1-8, characterized in that, Includes the following steps: a. System Trigger: The control and data acquisition system generates a trigger signal to control the 532nm and 1550nm wavelength pulsed lasers to generate pulsed light, and simultaneously controls the illumination source. The pulsed lasers of different wavelengths enter the fiber coupler, and then enter the arthroscopic probe through the first and second adjustable focusing collimators. The 1550nm wavelength laser is modulated by the electro-optic polarization modulator and then combined with the 532nm wavelength laser through the dichroic mirror. The combined light passes through the focusing lens and the beam splitter and finally reaches the surface of the tissue to be imaged. The illumination light illuminates the surface of the tissue to be imaged through the optical fiber. b. Data acquisition: The photoacoustic signal excited by the pulsed laser is reflected by the light-transmitting mirror and received by the ultrasonic transducer on the side wall of the arthroscope. It is then converted into an electrical signal and enters the signal amplifier through the coaxial cable. The amplified electrical signal is acquired by the acquisition card and sent to the computer. The optical signal passes through the rod lens group and enters the charge-coupled device through the beam splitter. The charge-coupled device converts the incident light signal into a charge output and enters the computer through the data line. c. Image Processing: The computer uses the acquired data for the reconstruction of optical, photoacoustic, polarized photoacoustic, and photoacoustic-elastic images. Photoacoustic image reconstruction: Utilizing the absorption of 532nm wavelength laser by hemoglobin, the photoacoustic signal generated by instantaneous thermal expansion is used to reconstruct the maximum projection image of the blood vessel through a maximum projection algorithm. Photoacoustic polarized image reconstruction: By using a hollow servo motor and a λ / 2 plate combined with different polarized laser states, the anisotropic absorption differences of the tissue sample are obtained, thereby reconstructing a quantitative anisotropic image of the tissue sample. Photoacoustic-elastic image reconstruction: By measuring the time required for the vibration displacement of the tissue sample surface to rise from zero to its maximum value, the elastic modulus of the tissue sample is calculated, and its quantitative elastic image is reconstructed.

Images