Living blood vessel and lymph multi-parameter quantitative photoacoustic microscopic imaging system

Abstract

The invention discloses a living blood vessel and lymph multi-parameter quantitative photoacoustic microscopic imaging system which comprises a high repetition frequency laser source, a photoacoustic scanning probe and a molecular imaging device. Through the cooperation of the multi-wavelength fast switching laser and the high-speed scanning probe, synchronous, dynamic and quantitative imaging of vascular function parameters and lymph concentration in a living tissue microenvironment is realized. The system has a video-level imaging rate and can capture a rapid biological process; through coaxial design of dispersion correction and a photoacoustic focus, high spatial resolution and high signal-to-noise ratio of a multispectral image are guaranteed; and the compact probe design realizes large-range scanning. The technology provides a powerful in-vivo visualization tool for research on life science problems such as tumor evolution and drug metabolism.

Description

Technical Field

[0001] This invention relates to the field of biomedical imaging technology, specifically to a multi-parameter quantitative photoacoustic microscopy imaging system for living blood vessels and lymph nodes. Background Technology

[0002] Photoacoustic imaging is a novel biomedical imaging technique that combines the high contrast of optical imaging with the deep penetration of ultrasound imaging. Optical resolution photoacoustic microscopy (OR-PAM), in particular, offers micrometer-level lateral resolution and shows great potential in observing angiogenesis, blood oxygen saturation, and hemodynamics. Although existing OR-PAM techniques have achieved some success in basic research, several key bottlenecks remain in the extraction of multiple parameters from the microenvironment of living tissues.

[0003] First, existing technologies lack sufficient information dimensions, making it difficult to comprehensively assess multiple parameters within living tissue, including blood vessels and lymphatic vessels. Most OR-PAM systems are limited by their laser sources, typically operating only at a single or a few wavelengths. This makes it difficult for the system to simultaneously acquire key physiological and pathological parameters with multiple dimensions and contrasts, such as blood oxygen saturation, hemoglobin concentration, blood flow velocity, and lymphatic vessel distribution, in a single acquisition, thus limiting a comprehensive understanding of the tissue microenvironment. Second, the imaging speed is too slow to meet the monitoring needs of dynamic biological processes. Traditional OR-PAM systems often use mechanical scanning platforms to move samples or probes, resulting in an extremely time-consuming imaging process; acquiring a complete three-dimensional image typically takes tens of minutes. Such a slow speed makes it impossible to effectively capture the dynamic changes of rapidly occurring biological events within the tissue microenvironment. Furthermore, existing technologies struggle to strike a balance between improving speed and maintaining performance. Optical scanning methods developed to address the speed issue, while increasing imaging rates, often come at the cost of sacrificing the size of the scanning field of view or the signal-to-noise ratio of the image. Other parallel detection technologies aimed at improving speed generally suffer from problems such as complex system structure and high hardware cost, which limit their promotion and application.

[0004] Therefore, there is an urgent need for a photoacoustic microscopy system that can simultaneously perform multi-parameter imaging and high-speed scanning of blood vessels and lymph in living tissues to meet the needs of visual research on the dynamic processes of blood vessels and lymph in living tissues. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a novel multi-wavelength rapid switching photoacoustic microscopy imaging system. This system can simultaneously acquire multiple functional parameters of the vascular network in the tumor microenvironment (such as blood oxygen saturation, hemoglobin concentration, blood flow velocity, etc.) and the structural information of lymphatic vessels at high spatiotemporal resolution, thereby providing a powerful imaging tool for the visualization study of the microenvironment of living tissues.

[0006] To achieve the above objectives, the present invention provides a live in vivo blood vessel and lymph multi-parameter quantitative photoacoustic microscopy imaging system, comprising: a high repetition rate laser source, a photoacoustic scanning probe, and a molecular imaging device;

[0007] The high repetition rate laser source is used to generate lasers of several wavelengths;

[0008] The photoacoustic scanning probe is used to scan biological tissues based on the generated laser to produce photoacoustic signals;

[0009] The molecular imaging device is used to acquire vascular function parameters and lymphatic concentration information of biological tissues based on photoacoustic signals.

[0010] Preferably, the high repetition rate laser source is a high repetition rate laser source capable of rapidly switching between visible light and near-infrared multispectral range.

[0011] Preferably, the high repetition rate laser source includes: a single-source nanosecond pulse laser, optical fibers of different lengths, and general-purpose optical components;

[0012] Using optical fibers of different lengths, laser light generated by a single-source nanosecond pulse laser is Raman scattered to produce multi-wavelength optical fibers.

[0013] Multi-wavelength optical fibers are coupled using optical elements and then fed into a subsequent photoacoustic scanning probe.

[0014] Preferably, the photoacoustic scanning probe includes: an objective lens, an ultrasonic sensor, a photoacoustic beam combiner, an acoustic lens, and an achromatic lens;

[0015] Multi-wavelength optical fibers are initially focused by an objective lens, then pass through an achromatic lens to correct for dispersion caused by different wavelengths. The focused beam is guided to biological tissue by a scanning mirror, exciting photoacoustic signals. As the photoacoustic propagates outward, it is captured and converged by an acoustic lens. The converged acoustic signal then passes through a photoacoustic combiner. The photoacoustic combiner utilizes its acoustic transmission and optical reflection properties to efficiently guide the acoustic waves to the ultrasonic sensor without interfering with the incident light path, and finally converts the acoustic signal into an electrical signal for acquisition.

[0016] Preferably, the photoacoustic beam combiner is made by bonding an aluminum-coated prism and an uncoated prism together. The aluminum coating can reflect the light beam and transmit ultrasonic waves, thereby achieving reflective photoacoustic imaging.

[0017] Preferably, the molecular imaging device uses a 500-600 nm laser to perform functional imaging of blood vessels within the tissue microenvironment;

[0018] Tracers with absorption peaks above 600 nm were used to inject living tissue in situ, and then the labeled lymphatic vessels were imaged with 640 nm light.

[0019] Preferably, the single-source nanosecond pulse laser is a 532 nm single-source nanosecond pulse laser, and the wavelength of the optical fiber includes 545 nm, 558 nm, and 640 nm.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention achieves simultaneous, dynamic, and quantitative imaging of vascular function parameters and lymphatic concentration in the microenvironment of living tissue through the synergy of multi-wavelength rapidly switching lasers and a high-speed scanning probe. The system boasts video-level imaging speeds, enabling the capture of rapid biological processes; dispersion correction and a coaxial photoacoustic focal point design ensure high spatial resolution and a high signal-to-noise ratio for multispectral images; and its compact probe design allows for wide-area scanning. This technology provides a powerful in vivo visualization tool for research on life science issues such as tumor evolution and drug metabolism. Attached Figure Description

[0022] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the system structure according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the multifunctional parameters of blood vessels and lymphatic concentration in the mouse microenvironment according to an embodiment of the present invention; Figure 2 In the figure, (a) represents hemoglobin; (b) represents blood oxygen saturation; (c) represents blood flow velocity; (d) represents the vascular structure results of 532nm wavelength imaging; and (e) represents the labeled lymph concentration results of 630nm wavelength imaging. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1

[0028] This embodiment provides a live in vivo blood vessel and lymph multi-parameter quantitative photoacoustic microscopy imaging system, including: a high repetition rate laser source, a photoacoustic scanning probe, and a molecular imaging device.

[0029] In this embodiment, the high repetition rate laser source is a high repetition rate laser source capable of rapidly switching between visible and near-infrared multispectral wavelengths. The Raman laser used in this embodiment employs a commercially available high-power Q-switched fiber laser to emit nanosecond pulses as the light source. The beam originating from the light source passes through an optical fiber to generate the wavelengths required for tumor imaging. During the multispectral generation stage, the light from the laser source is introduced into the optical fiber. By adjusting the energy of the light source and the length of the fiber, multiple wavelengths can be generated through the stimulated Raman scattering effect of the fiber.

[0030] The laser optical path in this embodiment mainly consists of a 532 nm single-source nanosecond pulsed laser, optical fibers, and some general-purpose optical components. Using optical fibers of different lengths, the 532 nm wavelength laser can be Raman-scattered to generate pulsed light at wavelengths of 545, 558, and 640 nm. Finally, multiple different beams are coupled together by optical components and fed into a subsequent high-speed photoacoustic microscope probe. A confocal method is used to achieve beam scanning and photoacoustic signal detection. Because the optical and acoustic signals are on the same focal plane, high imaging sensitivity and good image quality can be obtained.

[0031] The photoacoustic scanning probe in this embodiment is a high-speed, high-resolution, and high-sensitivity photoacoustic scanning probe. Real-time photoacoustic imaging requires the photoacoustic scanning probe to possess a large scanning range, high resolution, high speed, and high sensitivity. Traditional imaging methods are limited by mechanical spatial light, scanning platform, and linear displacement stage drive speed, resulting in relatively low scanning speeds and preventing high-speed imaging of blood vessels. Therefore, this embodiment uses a small, low-chromatic-difference photoacoustic probe and achieves high-speed, large-range scanning based on a voice coil scanner.

[0032] The miniature photoacoustic probe consists of an objective lens, an ultrasonic sensor, a photoacoustic combiner, an acoustic lens, and an achromatic lens. A multi-wavelength optical fiber generated by a high-repetition-rate laser source is collimated by a collimating lens and then focused by the objective lens. The focused beam is reflected by a scanning mirror connected to a voice coil scanner and guided to the sample surface for scanning. As the photoacoustic waves propagate outward, they are captured and converged by the acoustic lens. The converged acoustic signal then passes through the photoacoustic combiner, which utilizes its acoustic transmission and optical reflection properties to efficiently guide the sound waves to the ultrasonic sensor without interfering with the incident light path. Finally, the acoustic signal is converted into an electrical signal for acquisition.

[0033] The photoacoustic beam combiner is made by bonding an aluminum-coated prism to an uncoated prism. The aluminum coating reflects the light beam and transmits ultrasound, thus achieving reflective photoacoustic imaging. Before guiding the beam to the sample surface, an achromatic lens is used to minimize multispectral chromatic aberration and improve image quality.

[0034] In this embodiment, the ultrasonic sensor employs a broadband high-frequency (50MHz) piezoelectric sensor. The generated photoacoustic signal is received by a focusing acoustic lens, passes through a photoacoustic combiner, and is finally received by the sensor in contact with the coupling prism. Zemax software is used to simulate the propagation of multispectral (532-640 nm) signals through optical components such as the focusing lens and achromatic lens, calculating the relative distances and placement of these components and calibrating for multispectral dispersion. Simultaneously, k-Wave simulation is used to simulate the propagation of sound waves within the acoustic devices. By fine-tuning the position of the focusing lens, alignment of the optical and acoustic focal points is ensured to achieve a high signal-to-noise ratio for the photoacoustic signal.

[0035] Finally, the molecular imaging device acquires vascular function parameters and lymphatic concentration information of biological tissues based on photoacoustic signals. Photoacoustic functional imaging is based on the absorption of different spectra by the tested object. Since hemoglobin in blood has strong absorption of light below 600 nm, a 500-600 nm laser can be used to perform functional imaging of blood vessels in the tissue microenvironment, including measuring and calibrating blood oxygen saturation, blood flow velocity, and relative hemoglobin concentration. For light above 600 nm, absorption by hemoglobin is weak; therefore, tracers with absorption peaks above 600 nm (such as Evans blue, which has strong absorption in the 620-640 nm range) can be injected into living tissue in situ, and then 640 nm light can be used to image the labeled lymphatic vessels. Through continuous high-speed scanning, dynamic quantitative imaging of vascular physiological parameters and changes in lymphatic concentration over time within the tissue microenvironment can be performed simultaneously. Because the light source achieves nanosecond-level rapid wavelength switching, the system can simultaneously acquire data for all the above parameters in a single high-speed scan, achieving true synchronous multi-parameter functional imaging.

[0036] Example 2

[0037] The following embodiment details how the present invention solves technical problems in practical work. (Refer to...) Figure 1 The process of setting up the imaging system is as follows:

[0038] (1) A 532 nm single-source nanosecond pulsed laser, optical fiber, and some general-purpose optical components are used. Stimulated Raman scattering of the 532 nm wavelength can generate pulsed light at wavelengths of 545, 558, and 640 nm. Finally, multiple different beams are coupled together by optical components and fed into a high-speed photoacoustic microscope probe. The beam scanning and photoacoustic signal detection are achieved by using a confocal method.

[0039] (2) A small photoacoustic probe is used, which consists of an objective lens, an ultrasonic sensor, a photoacoustic combiner, an acoustic lens, and an achromatic lens. Multi-wavelength fiber light is collimated by a collimating lens and then focused by the objective lens. The focused beam is reflected by a scanning mirror connected to a voice coil scanner and guided to the sample surface for scanning. The photoacoustic combiner is made by bonding an aluminum-coated prism and an uncoated prism. The aluminum coating can reflect the beam and transmit ultrasonic waves, thereby realizing reflective photoacoustic imaging. The achromatic lens can minimize multispectral chromatic aberration and improve imaging quality. The ultrasonic sensor is a broadband high-frequency (50MHz) piezoelectric sensor. The generated photoacoustic light is received by the focusing acoustic lens, passes through the photoacoustic combiner, and is finally received by the sensor in contact with the coupling prism. The multispectral (532~640 nm) light passing through the optical focusing lens, achromatic lens, and other optical components is simulated using Zemax software. The relative distance and placement of the components are calculated to calibrate the multispectral dispersion problem. Simultaneously, k-Wave is used to perform acoustic simulation of the propagation of sound waves in acoustic devices. By fine-tuning the position of the optical focusing lens, the alignment of the optical focus and the acoustic focus is ensured to achieve a high signal-to-noise ratio for the photoacoustic signal.

[0040] Multi-contrast photoacoustic technology and molecular imaging include the following workflow:

[0041] (1) Start the photoacoustic microscopy system, open the Zemax software and preheat the laser.

[0042] (2) Fix the imaging part to the bracket, cover it with a transparent water tank, and immerse the photoacoustic probe in the water tank.

[0043] (3) Perform a scan and export the data.

[0044] The final imaging results are as follows Figure 2 As shown.

[0045] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A live in vivo multi-parameter quantitative photoacoustic microscopy imaging system for blood vessels and lymph nodes, characterized in that, include: High repetition rate laser source, photoacoustic scanning probe and molecular imaging device; The high repetition rate laser source is used to generate lasers of several wavelengths; The photoacoustic scanning probe is used to scan biological tissues based on the generated laser to produce photoacoustic signals; The molecular imaging device is used to acquire vascular function parameters and lymphatic concentration information of biological tissues based on photoacoustic signals.

2. The in vivo multi-parameter quantitative photoacoustic microscopy imaging system for blood vessels and lymph nodes according to claim 1, characterized in that, The high repetition rate laser source is a high repetition rate laser source that can quickly switch between visible light and near-infrared multispectral range.

3. The in vivo vascular and lymphatic multi-parameter quantitative photoacoustic microscopy imaging system according to claim 2, characterized in that, The high repetition rate laser source includes: a single-source nanosecond pulse laser, optical fibers of different lengths, and general-purpose optical components; Using optical fibers of different lengths, laser light generated by a single-source nanosecond pulse laser is Raman scattered to produce multi-wavelength optical fibers. Multi-wavelength optical fibers are coupled using optical elements and then fed into a subsequent photoacoustic scanning probe.

4. The in vivo multi-parameter quantitative photoacoustic microscopy imaging system for blood vessels and lymph nodes according to claim 1, characterized in that, The photoacoustic scanning probe includes: an objective lens, an ultrasonic sensor, a photoacoustic beam combiner, an acoustic lens, and an achromatic lens; Multi-wavelength optical fibers are initially focused by an objective lens, then pass through an achromatic lens to correct for dispersion caused by different wavelengths. The focused beam is guided to biological tissue by a scanning mirror, exciting photoacoustic signals. As the photoacoustic propagates outward, it is captured and converged by an acoustic lens. The converged acoustic signal then passes through a photoacoustic combiner. The photoacoustic combiner utilizes its acoustic transmission and optical reflection properties to efficiently guide the acoustic waves to the ultrasonic sensor without interfering with the incident light path, and finally converts the acoustic signal into an electrical signal for acquisition.

5. The in vivo vascular and lymphatic multi-parameter quantitative photoacoustic microscopy imaging system according to claim 4, characterized in that, The photoacoustic beam combiner is made by bonding an aluminum-coated prism and an uncoated prism together. The aluminum coating can reflect the light beam and transmit ultrasound waves, thus enabling reflective photoacoustic imaging.

6. The in vivo multi-parameter quantitative photoacoustic microscopy imaging system for blood vessels and lymph nodes according to claim 1, characterized in that, The molecular imaging device uses a 500-600 nm laser to perform functional imaging of blood vessels within the tissue microenvironment. Tracers with absorption peaks above 600 nm were used to inject living tissue in situ, and then the labeled lymphatic vessels were imaged with 640 nm light.

7. The in vivo multi-parameter quantitative photoacoustic microscopy imaging system for blood vessels and lymph nodes according to claim 3, characterized in that, The single-source nanosecond pulsed laser is a 532 nm single-source nanosecond pulsed laser, and the wavelengths of the optical fibers include 545 nm, 558 nm, and 640 nm.

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