Multimodal imaging catheter and multimodal imaging system

Abstract

The present application relates to the field of intravascular intervention imaging medical instruments, in particular to a multi-modal imaging catheter and a multi-modal imaging system, the catheter comprises a light beam transmission part and a front-end lens connected in sequence, the front-end lens comprises a side reflection part and a separate focusing part; the light beam transmission part is used for transmitting OCT imaging light and fluorescence excitation light to the front-end lens; and for transmitting the light reflected by the side reflection part for imaging; the side reflection part is used for changing the direction of the light path; the separate focusing part is used for focusing the OCT imaging light and the fluorescence excitation light to a target position by using a low numerical aperture mode; and for collecting the OCT scattered light scattered by the OCT imaging light after passing through the tissue at the target position, collecting the fluorescence emission light excited by the fluorescence excitation light at the target position, and realizing the focusing of the fluorescence emission light by using a high numerical aperture mode to obtain the light for imaging.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of intravascular interventional imaging medical devices, in particular to a multi-modal imaging catheter and a multi-modal imaging system. BACKGROUND

[0002] Current coronary heart disease has become the world's first deadly disease, in which atherosclerosis is the main cause of coronary heart disease. Intravascular interventional imaging technology has a great significance for accurately identifying atherosclerotic lesions and guiding clinical treatment programs. Intravascular interventional imaging technology refers to a method of inserting a catheter into a diseased blood vessel through vascular puncture technology to perform imaging examination on the diseased area.

[0003] Optical coherence tomography (OCT) imaging through detecting the scattering intensity of light at different depths of the tissue, is a tomographic imaging method for blood vessels, and is currently the highest resolution intravascular interventional imaging technology. However, this imaging method can only perform morphological structure imaging of the blood vessels, and cannot further reflect the molecular composition and activity inside the plaque. The growth of atherosclerotic plaques is a complex molecular regulation process, so it is still impossible to accurately predict the development of plaques and the occurrence of future coronary events in the clinic. The development of molecular imaging provides a new research method and diagnostic basis for vascular atherosclerosis. Among them, fluorescence imaging can be used to analyze the key factors and conditions of atherosclerotic plaque formation by selectively exciting fluorophores to display specific molecules, cells or biological processes, and has good sensitivity and imaging specificity, which can provide more reference for atherosclerosis research and diagnosis. Therefore, multi-modal optical imaging combining OCT and fluorescence has become a research hotspot.

[0004] Currently, one type of intravascular OCT-fluorescence imaging system uses a short-wavelength, single-photon excitation method for fluorescence imaging, which limits the depth of fluorescence imaging, and the depth of fluorescence imaging has a certain gap compared with OCT imaging. Another type of OCT-fluorescence endoscopy imaging system uses a two-photon excitation method for fluorescence imaging, which can effectively improve the depth of fluorescence imaging. However, due to the requirement of intravascular imaging to use an extremely thin imaging catheter for detection, the aperture of the imaging lens is limited, which makes it impossible to effectively focus the fluorescence at a position far from the catheter. Therefore, the fluorescence of deep tissues cannot be efficiently collected by the optical fiber, resulting in that it is still difficult to achieve the ideal imaging depth effect.

[0005] And, when using a common optical path structure to optically focus the OCT imaging light and the fluorescence excitation light, a problem of spatial mismatch of the focusing positions occurs, so that spatially registered multi-modal images cannot be obtained. When using a double optical path to separately focus the OCT imaging light and the fluorescence excitation light, it is also difficult to focus the OCT imaging light and the fluorescence excitation light at the same position, which brings difficulty to subsequent complex image registration, and the double optical path increases the size of the imaging catheter, limiting its application in smaller blood vessels. SUMMARY

[0006] In view of the above problems of the prior art, the purpose of the present application is to provide a multi-modal imaging catheter and a multi-modal imaging system, which can improve the fluorescence imaging depth and obtain the best spatially registered multi-modal images of blood vessels.

[0007] To solve the above problems, the present application provides a multi-modal imaging catheter, comprising a light beam transmission part and a front-end lens connected in sequence, wherein the front-end lens comprises a lateral reflection part and a separate focusing part.

[0008] The light beam transmission part is used for transmitting the OCT imaging light and the fluorescence excitation light to the front-end lens, wherein the wavelengths of the OCT imaging light and the fluorescence excitation light are within a preset wavelength range; and for transmitting the light for imaging reflected by the lateral reflection part.

[0009] The lateral reflection part is used for changing the direction of the optical path, so that the OCT imaging light and the fluorescence excitation light are emitted laterally through the separate focusing part; and for reflecting the light for imaging collected by the separate focusing part to the light beam transmission part.

[0010] The separate focusing part is used for focusing the OCT imaging light and the fluorescence excitation light at a target position by using a low numerical aperture mode; and for collecting the OCT scattered light scattered by the OCT imaging light at the target position; and for focusing at the target position by using a high numerical aperture mode, and collecting the fluorescence emission light excited by the fluorescence excitation light at the target position, to obtain the light for imaging.

[0011] Further, the fluorescence excitation light is two-photon fluorescence excitation light, and the fluorescence excitation light excites the fluorescence emission light at the target position by two-photon excitation.

[0012] Further, the light beam transmission part comprises a first optical fiber having a double cladding.

[0013] The core of the first optical fiber is used for transmitting the OCT imaging light and the fluorescence excitation light.

[0014] A first cladding of the first optical fiber is wrapped outside a lateral wall of the core for transmitting the fluorescent emission light reflected by the lateral reflection part;

[0015] A second cladding of the first optical fiber is wrapped outside a lateral wall of the first cladding for transmitting the fluorescent emission light in the first cladding.

[0016] Further, a beam expanding part is arranged between the beam transmitting part and the front-end lens, the beam expanding part is used for expanding the OCT imaging light and the fluorescent excitation light transmitted by the beam transmitting part, and transmitting the expanded OCT imaging light and the fluorescent excitation light to the front-end lens.

[0017] Further, the beam expanding part comprises a second optical fiber, a diameter of the second optical fiber is greater than or equal to a diameter of the first optical fiber.

[0018] Further, the separating focusing part comprises a spherical lens, the spherical lens comprises a first spherical surface area located at a center position of the spherical lens and a second spherical surface area located around the first spherical surface area, a focusing focal length of the first spherical surface area is greater than a focusing focal length of the second spherical surface area.

[0019] Further, the separating focusing part comprises an array of superlenses, the array of superlenses comprises a first array area located at a center position of the array of superlenses and a second array area located around the first array area, a focusing focal length of the first array area is greater than a focusing focal length of the second array area.

[0020] Another aspect of the present application provides a multi-modal imaging system, comprising an OCT imaging module, a fluorescence imaging module, a combined and separated optical path module, and a multi-modal imaging catheter as described above;

[0021] The OCT imaging module is configured to generate OCT imaging light, and to acquire OCT scattered light scattered by the OCT imaging light from a target position, and to process the OCT scattered light to obtain an OCT imaging result.

[0022] The fluorescence imaging module is configured to generate fluorescent excitation light, and to acquire fluorescent emission light excited by the fluorescent excitation light at the target position, and to process the fluorescent emission light to obtain a fluorescence imaging result.

[0023] The combination is combined with a separation optical path module, which is used for combining the OCT imaging light and the fluorescence excitation light, and transmitting the combined OCT imaging light and the fluorescence excitation light to the multi-modal imaging catheter; and obtaining the light for imaging collected by the multi-modal imaging catheter, separating the OCT scattered light and the fluorescence emission light from the light for imaging, and transmitting the OCT scattered light to the OCT imaging module and transmitting the fluorescence emission light to the fluorescence imaging module.

[0024] Further, the OCT imaging module comprises:

[0025] An OCT light source is configured to generate OCT imaging light.

[0026] An interference optical path is configured to perform interference processing on the obtained OCT scattered light to obtain interference OCT scattered light.

[0027] A photoelectric detector is configured to convert the interference OCT scattered light into an OCT imaging signal.

[0028] An OCT imaging processing module is configured to process the OCT imaging signal to obtain an OCT imaging result.

[0029] Further, the fluorescence imaging module comprises:

[0030] A fluorescence excitation light source is configured to generate fluorescence excitation light.

[0031] A filtering optical path is configured to perform filtering processing on the obtained fluorescence emission light to obtain filtered fluorescence emission light.

[0032] A fluorescence detector is configured to convert the filtered fluorescence emission light into a fluorescence imaging signal.

[0033] A fluorescence imaging processing module is configured to process the fluorescence imaging signal to obtain a fluorescence imaging result.

[0034] Due to the above technical scheme, the present application has the following beneficial effects:

[0035] According to the multi-modal imaging catheter of the embodiment of the present application, the intravascular multi-modal imaging mode of combining OCT imaging and fluorescence imaging is used, and the two modes use imaging light with similar wavelengths, and optical focusing is performed through the lens of the same imaging catheter, so that the focused light spot has better spatial matching degree due to the similar wavelengths of the OCT imaging light and the fluorescence excitation light, thereby the spatially registered intravascular multi-modal image can be obtained, the difficulty of subsequent image processing is reduced, and the imaging catheter size does not need to be increased, so that the imaging catheter can be applied in smaller blood vessels and has a wide application range.

[0036] In addition, by adopting the separated focusing mode, the OCT imaging light and the fluorescence excitation light are focused by adopting the low numerical aperture focusing mode, which can not only ensure the OCT imaging depth, but also improve the fluorescence imaging depth. In addition, by expanding the numerical aperture of the fluorescence detection part of the lens, the fluorescence emission light is collected and focused by adopting the high numerical aperture focusing mode, which can improve the collection efficiency of the fluorescence excited by the deep tissue, so that the fluorescence imaging can achieve the ideal imaging depth effect. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0038] Figure 1 is a structural schematic diagram of a multi-modal imaging catheter provided by an embodiment of the present application;

[0039] Figure 2 is a structural schematic diagram of a multi-modal imaging catheter provided by another embodiment of the present application;

[0040] Figure 3 is a structural schematic diagram of a multi-modal imaging catheter provided by an embodiment of the present application;

[0041] Figure 4 is a structural schematic diagram of a multi-modal imaging catheter provided by another embodiment of the present application;

[0042] Figure 5 is a schematic diagram of the arrangement of the superlens unit of the superlens array provided by an embodiment of the present application;

[0043] Figure 6 is a structural schematic diagram of a multi-modal imaging system provided by an embodiment of the present application;

[0044] Figure 7 is a structural schematic diagram of an OCT imaging module and a fluorescence imaging module provided by an embodiment of the present application;

[0045] Figure 8 is a structural schematic diagram of a multi-modal imaging system provided by another embodiment of the present application. DETAILED DESCRIPTION

[0046] In the following, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application by persons in the technical field of the present application, obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons in the technical field of the present application without creative labor are within the scope of protection of the present application.

[0047] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, device, product or apparatus that includes a series of steps or units does not necessarily have to include only those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to such processes, methods, products or apparatus.

[0048] Reference is made to the drawings Figure 1 which shows a structural schematic diagram of a multi-modal imaging catheter provided by an embodiment of the present application. The multi-modal imaging catheter can be applied to the scene of intravascular multi-modal optical imaging, for OCT imaging and fluorescence imaging of the blood vessels of a patient, to obtain multi-modal images of the blood vessels that can reflect the structure of the blood vessels and reflect the molecular components and activities, to provide more reference basis for research and diagnosis of atherosclerosis and the like. Specifically, as shown in Figure 1 , the multi-modal imaging catheter 100 can include a light beam transmission part 110 and a front-end lens 120 connected in sequence, and the front-end lens 120 can include a lateral reflection part 121 and a separate focusing part 122.

[0049] In the embodiment of the present application, the light beam transmission unit 110 can be used to transmit the OCT imaging light and the fluorescence excitation light from the light source to the front-end lens 120. The OCT imaging light can be generated by an OCT light source, and the fluorescence excitation light can be generated by a fluorescence excitation light source. After the OCT imaging light is generated, it can pass through an interference light path, and the fluorescence excitation light passing through a filtering light path is combined in a combination and separation light path module, and then transmitted to the light beam transmission unit 110 of the multi-modal imaging catheter 100. The light beam transmission unit 110 then transmits the combined OCT imaging light and fluorescence excitation light to the front-end lens 120, which focuses and irradiates the imaging tissue at the target position. The target position can be a lesion area position in the blood vessel of a patient (for example, the position of an atherosclerotic plaque), and the present application is not limited in this regard.

[0050] Specifically, the fluorescence excitation light can be two-photon fluorescence excitation light or one-photon fluorescence excitation light, and the present application is not limited in this regard. The wavelengths of the OCT imaging light and the fluorescence excitation light can both be within a preset wavelength range, which can be determined according to actual needs, taking into account the absorption spectrum band of the imaging fluorophore. For example, in the case of two-photon fluorescence excitation light, the wavelength range can be determined as the near-infrared region I and region II, and in the case of one-photon fluorescence excitation light, the wavelength range can be determined as the near-infrared region I or other fluorophore absorption spectrum band range, and the present application is not limited in this regard.

[0051] In a preferred embodiment, the OCT light source can use a commonly used 1310 nm OCT light source for intravascular imaging, and the fluorescence excitation light source can use a 1550 nm short pulse laser light source, i.e., the wavelength of the OCT imaging light can be 1310 nm, and the wavelength of the fluorescence excitation light can be 1550 nm, and the fluorescence excitation light is excited by two-photon excitation to obtain fluorescence emission light.

[0052] In actual applications, the fluorescence imaging part can use a 1550 nm wavelength two-photon excitation method to increase the penetration depth. Because the absorption of light in most biological tissues is negligible compared to scattering, especially in the near-infrared wavelength range. And the size of most biological molecules is relatively large, and the scattering of light in the tissue can be described by Mie scattering. Specifically, the scattering of a simple spherical particle can be described by the following formula:

[0053]

[0054] where I is the scattered light intensity, I0 is the incident light intensity, θ S is the scattering angle, λ is the wavelength of the light, R is the distance from the particle to the light detector, n is the refractive index of the particle, and d is the diameter of the particle.

[0055] It can be seen that, when other conditions are constant, the longer the wavelength, the weaker the light intensity of the light scattering to the surrounding, and thus the 1550nm excitation light has lower scattering characteristics than the excitation light below 800nm. Therefore, lower tissue absorption and scattering enable the 1550nm two-photon fluorescence excitation light to image deeper tissues.

[0056] Moreover, since the 1550nm wavelength of the fluorescence excitation light and the 1310nm wavelength of the OCT imaging light are similar, the spatial positions are more matched after being emitted from the same optical fiber and focused using a common lens. For example, at the wavelengths of 1550nm, 1310nm and 800nm, the refractive indexes of the optical fiber material (pure silica) are 1.4440, 1.4468 and 1.4533 respectively. It can be seen that the refractive index difference between 800nm and 1310nm is larger, and the spatial position matching degree of the focus under the same lens is poorer. The refractive index difference between 1550nm and 1310nm is smaller, and the spatial position matching degree of the focus under the same lens is better. In addition, in a conventional communication optical fiber (such as SMF-28e), the light of 800nm will generate high-order modes, further affecting the focusing effect. The light of 1550nm and the light of 1310nm can propagate in a single mode, and will not affect the focusing effect.

[0057] It should be noted that the above embodiment of the OCT light source using a 1310nm OCT light source and the fluorescence excitation light source using a 1550nm short pulse laser light source is only an example. In actual applications, other wavelength similar and low dispersion coefficient and high tissue penetration infrared imaging wavelength bands can also be used. For example, the OCT light source can be a 1310nm, 1550nm or other near-infrared two-band OCT light source, and the fluorescence excitation light source can be a 1310nm, 1550nm, 1700nm or other near-infrared two-band short pulse laser light source, and the present application does not make specific limitations.

[0058] It can be understood that, by using the near-infrared two-band imaging light with similar wavelengths in the OCT imaging and fluorescence imaging modalities, the OCT imaging depth can be ensured, and by using the two-photon excitation method, especially the near-infrared two-band two-photon excitation method, the tissue penetration ability is higher than that of other current intravascular fluorescence excitation light bands, and a higher fluorescence imaging depth can be obtained. Moreover, since the wavelengths of the OCT imaging light and the fluorescence excitation light are similar, the spatial matching degree of the two modalities focused light spots is better, and thus the best spatially registered vascular multi-modal images can be obtained.

[0059] In one possible embodiment, the OCT light source can be a 1310 nm OCT light source commonly used for intravascular imaging, and the fluorescence excitation light source can also be a 1550 nm or 775 nm continuous light source, that is, the wavelength of the OCT imaging light can be 1310 nm, the wavelength of the fluorescence excitation light can be 1550 nm or 775 nm, and the fluorescence excitation light excites the fluorescence emission light through single-photon excitation.

[0060] It should be noted that the above embodiment in which the OCT light source is a 1310 nm OCT light source and the fluorescence excitation light source is a 1550 nm or 775 nm continuous light source is only an example. In actual applications, other wavelength combinations can also be used, and the embodiments of the present application do not make specific limitations in this regard.

[0061] In the embodiments of the present application, the lateral reflection part 121 can be used to change the direction of the light path, reflect the OCT imaging light and the fluorescence excitation light to the separation focusing part 122, and make the OCT imaging light and the fluorescence excitation light exit laterally through the separation focusing part 122, so that the imaging catheter can perform annular scanning on the blood vessel.

[0062] In the embodiments of the present application, the separation focusing part 122 can realize the separate focusing of the OCT imaging light, the fluorescence excitation light, the OCT scattered light, and the fluorescence emission light. The OCT scattered light can be light scattered by the OCT imaging light at the target position, and the fluorescence emission light can be fluorescence emitted by the fluorophore after the fluorophore enriched in the tissue at the target position is excited to a high energy level by the fluorescence excitation light.

[0063] Specifically, the separation focusing part 122 can be used to focus the OCT imaging light and the fluorescence excitation light at the target position by using a low numerical aperture focusing method. In actual applications, since the OCT imaging light requires good resolution in a relatively long depth range, the conventional low numerical aperture focusing method can be used for focusing to ensure that the OCT beam has sufficient focal depth. For the excitation of the fluorescence emission light, the spot size in a relatively long depth range also needs to be ensured, and therefore the focusing scheme can be shared, and the conventional low numerical aperture focusing method is used to optically focus the OCT imaging light and the fluorescence excitation light through the same lens of the imaging catheter.

[0064] It can be understood that, by sharing the focusing scheme and using the conventional low numerical aperture focusing method to optically focus the OCT imaging light and the fluorescence excitation light through the same lens, the size of the imaging catheter does not need to be increased, so that it can also be applied in smaller blood vessels and has a wider range of applications.

[0065] In the embodiment of the present application, the OCT imaging light irradiates the tissue at the target position and can be collected by the imaging catheter to obtain the OCT scattered light after scattering by the tissue. The fluorescence excitation light irradiates the tissue at the target position, and the fluorophore enriched in the tissue can be excited to a high energy level. When the electron of the fluorophore jumps back to a low energy level, fluorescence can be emitted, which can be collected by the imaging catheter to obtain the fluorescence emission light.

[0066] Specifically, in the case of two-photon fluorescence excitation light, the fluorescence excitation light at the target position can excite the fluorophore enriched in the tissue to a high energy level by two-photon excitation, thereby exciting the fluorescence emission light. For example, 1550nm short pulse excitation light can excite the fluorophore with an absorption spectrum near 775nm to a high energy level by two-photon excitation, thereby emitting fluorescence when the electron of the fluorophore jumps back to a low energy level. The specific principle of two-photon excitation can refer to the prior art, and the embodiment of the present application will not be repeated here.

[0067] Specifically, in the case of two-photon fluorescence excitation light, the fluorescence excitation light at the target position can excite the fluorophore enriched in the tissue to a high energy level by two-photon excitation, thereby exciting the fluorescence emission light. For example, 1550nm short pulse excitation light can excite the fluorophore with an absorption spectrum near 775nm to a high energy level by two-photon excitation, thereby emitting fluorescence when the electron of the fluorophore jumps back to a low energy level. The specific principle of two-photon excitation can refer to the prior art, and the embodiment of the present application will not be repeated here.

[0068] In the embodiment of the present application, in order to improve the depth of fluorescence imaging, it is also necessary to improve the collection efficiency of the excited fluorescence of the deep tissue. In actual application, in the deep tissue, the excited fluorescence photons scatter through the tissue, and almost no light can maintain the original direction of travel. Most of them are emitted from the tissue surface in an area larger than the fluorescence excitation light spot area, and have a large spatial angle distribution. If a low numerical aperture focusing method is used, only a small angle range of fluorescence emission light can be received, which limits the fluorescence collection efficiency.

[0069] Therefore, the embodiment of the present application can adopt the separated focusing scheme. For the single-mode OCT imaging light and the fluorescence excitation light, since the exit divergence angle is small, only a small area is exited in the near-center region of the lens, and the imaging requires sufficient focal depth, so the low numerical aperture focusing mode is adopted. For the fluorescence emission light emitted by the fluorescent group, since the spatial angle range is large, in the part of the lens that can accept the fluorescence emission light, the high numerical aperture focusing mode is adopted, and the receiving area is expanded, so as to improve the collection efficiency of the deep fluorescence signal. For the OCT scattering light scattered back by the OCT imaging light, the relative proportion is relatively high, so the high numerical aperture focusing mode is not required for focusing, but the existing low numerical aperture focusing mode can be adopted for focusing.

[0070] Specifically, the separated focusing part 122 can also be used to collect the OCT scattering light scattered by the OCT imaging light at the target position, and the low numerical aperture focusing mode is adopted to realize the focusing of the OCT scattering light. The separated focusing part 122 can also realize the focusing at the target position by using the high numerical aperture mode, and collect the fluorescence emission light excited by the fluorescence excitation light at the target position. That is, the separated focusing part 122 can collect the light for imaging including the OCT scattering light and the fluorescence emission light.

[0071] Specifically, the separated focusing part 122 can be realized by combining focusing surfaces with different curvatures, or by using superlenses or microlenses with strict spatial arrangement. The specific implementation scheme of the separated focusing will be described in detail later. The specific principles of the low numerical aperture focusing mode and the high numerical aperture focusing mode can refer to the prior art, and the embodiment of the present application will not be described here.

[0072] It can be understood that by adopting the separated focusing mode, the OCT imaging light and the fluorescence excitation light are focused by using the low numerical aperture focusing mode, which can not only ensure the OCT imaging depth, but also improve the fluorescence imaging depth. By expanding the numerical aperture of the fluorescence detection part of the lens, the fluorescence emission light is collected and focused by using the high numerical aperture focusing mode, which can improve the collection efficiency of the fluorescence excited by the deep tissue, so that the fluorescence imaging can achieve the ideal imaging depth effect.

[0073] In the embodiment of the present application, the lateral reflection part 121 can also be used to change the direction of the light path, and reflect the light for imaging collected by the separated focusing part 122 to the light beam transmission part 110. The light for imaging can be transmitted to the imaging module by the light beam transmission part 110 for processing.

[0074] Specifically, the lateral reflection part 121 can be obliquely arranged at one end of the front end lens 120 away from the light beam transmission part 110. The oblique angle of the lateral reflection part 121 can be set according to actual conditions, and only needs to match the oblique angle of the lateral reflection part 121 with the separation focusing part 122, so that the OCT imaging light and the fluorescence excitation light reflected by the lateral reflection part 121 can pass through the separation focusing part 122, and the OCT scattered light and the fluorescence emission light reflected by the lateral reflection part 121 can enter the light beam transmission part 110. The present embodiment does not specifically limit the oblique angle of the lateral reflection part 121.

[0075] In the embodiment of the present application, the light beam transmission part 110 can be used to transmit the light reflected by the lateral reflection part 121 for imaging to the combined and separated optical path module. After the OCT scattered light and the fluorescence emission light are separated by the combined and separated optical path module, they are transmitted to the OCT imaging module and the fluorescence imaging module for processing to obtain corresponding multi-modal images.

[0076] Specifically, the light beam transmission part 110 can include a first optical fiber with a double cladding. The core of the first optical fiber can be used to transmit the OCT imaging light and the fluorescence excitation light, and the core can also be used to transmit the OCT scattered light reflected by the lateral reflection part 121. The first cladding of the first optical fiber can be wrapped on the outer sidewall of the core, and the first cladding can be used to transmit the fluorescence emission light reflected by the lateral reflection part 121. The second cladding of the first optical fiber can be wrapped on the outer sidewall of the first cladding to make the fluorescence emission light transmit in the first cladding.

[0077] In actual application, the core can transmit single-mode light, such as the OCT imaging light and the fluorescence excitation light, and the OCT scattered light. The first cladding can be wrapped on the outer sidewall of the core, and the first cladding can transmit multi-mode light, such as the fluorescence emission light. Specifically, the refractive index of the core can be greater than the refractive index of the first cladding, so that the OCT imaging light, the fluorescence excitation light and the OCT scattered light are totally reflected between the core and the first cladding, thereby enabling the OCT imaging light, the fluorescence excitation light and the OCT scattered light to transmit in the core.

[0078] In actual application, the refractive index of the first cladding can be greater than the refractive index of the second cladding. The second cladding can be wrapped on the outer sidewall of the first cladding, and the second cladding is not used to transmit light, but is used to make the fluorescence emission light totally reflected between the first cladding and the second cladding, thereby enabling the fluorescence emission light to transmit in the first cladding.

[0079] Specifically, the first optical fiber in the light beam transmission part 110 can use ordinary double-clad optical fiber, or can use photonic crystal fiber, hollow double-clad optical fiber and other special optical fibers to improve the damage threshold of the optical fiber and the collection efficiency of the fluorescence signal, and reduce the nonlinear effect of light transmission. The present embodiment does not specifically limit the type and material of the first optical fiber.

[0080] It can be understood that by using the double-clad optical fiber, the fluorescent receiving area can be expanded, and the numerical aperture of the fluorescent detection part lens can be expanded in combination with the separation focusing mode, so that the receiving efficiency of the deep layer fluorescence can be improved, and the imaging depth is further improved.

[0081] In the embodiment of the present application, the OCT scattered light obtained by separating the combination and separation optical path module can be converted into an electrical signal (i.e. OCT imaging signal) by a photoelectric detector after interference by an interference optical path, and the OCT imaging result including blood vessel structure information can be obtained by sampling and data reconstruction. The fluorescent emission light obtained by separating the combination and separation optical path module can be detected by a fluorescent detector after filtering by a filtering optical path, forming a fluorescent imaging signal, and then obtaining a fluorescent imaging result including fluorescence intensity and lifetime information.

[0082] It should be noted that the detailed process of processing the OCT scattered light to obtain the OCT imaging result and processing the fluorescent emission light to obtain the fluorescent imaging result can refer to the prior art, and the embodiment of the present application will not be described here.

[0083] In one possible embodiment, in combination with the reference drawings attached Figure 2 The beam expansion part 130 can be used to expand the OCT imaging light and the fluorescent excitation light transmitted by the beam transmission part 110, and transmit the expanded OCT imaging light and the fluorescent excitation light to the front-end lens 120.

[0084] In the embodiment of the present application, the function of the beam expansion part 130 is to expand the spot of the OCT imaging light and the fluorescent excitation light. Specifically, the beam expansion part 130 can include a second optical fiber, and the diameter of the second optical fiber can be greater than or equal to the diameter of the first optical fiber in the beam transmission part 110.

[0085] Specifically, the second optical fiber in the beam expansion part 130 can use a hollow optical fiber, a step-index multimode optical fiber, a gradient-index multimode optical fiber, etc. The type and material of the second optical fiber are not limited in the embodiment of the present application.

[0086] It can be understood that by expanding the spot of the OCT imaging light and the fluorescent excitation light through the beam expansion part, the light beam can be focused deeper, and it is beneficial to realize a larger focusing angle and improve the numerical aperture of the lens.

[0087] In one specific embodiment, in combination with the reference drawings attached Figure 3The separation and focusing part 122 can include a spherical lens, which can include a first spherical area 1221 located at the center of the spherical lens and a second spherical area 1222 located around the first spherical area 1221, and the focusing focal length of the first spherical area 1221 is greater than that of the second spherical area 1222.

[0088] Specifically, the radius of curvature of the first spherical area 1221 can be greater than that of the second spherical area 1222. The first spherical area 1221 can be used to achieve low numerical aperture focusing of OCT imaging light and fluorescence excitation light, and the second spherical area 1222 can be used to achieve high numerical aperture focusing of fluorescence emission light.

[0089] In actual application, the light beam transmission part 110 can use a double-clad optical fiber, the light beam expansion part 130 can use a segment of coreless optical fiber, and the diameter of the coreless optical fiber can be equal to that of the double-clad optical fiber. The front-end lens 120 can use spherical focusing. Unlike the conventional OCT spherical catheter, the focusing part in the embodiment of the present application can use two spherical surfaces with different curvatures. The near-center area of the front-end lens 120 (i.e. the first spherical area 1221) uses a spherical surface with a larger radius of curvature, thereby extending the focal length, and the edge area outside the center area (i.e. the second spherical area 1222) uses a spherical surface with a smaller radius of curvature, thereby improving the focusing ability, increasing the spatial focusing angle, and improving the collection efficiency of excited fluorescence.

[0090] In another specific embodiment, in combination with the description of the accompanying drawings Figure 4 The separation and focusing part 122 can include an array of superlenses, which can include a first array area 1223 located at the center of the array and a second array area 1224 located around the first array area 1223, and the focusing focal length of the first array area 1223 is greater than that of the second array area 1224.

[0091] Specifically, each superlens unit of the first array area 1223 can be used to achieve low numerical aperture focusing of OCT imaging light and fluorescence excitation light, and the second array area 1224 can be used to achieve high numerical aperture focusing of fluorescence emission light.

[0092] In practical applications, the light beam transmission part 110 can use a double-clad optical fiber, the light beam expansion part 130 can use a segment of a hollow-core optical fiber, and the diameter of the hollow-core optical fiber can be greater than the diameter of the double-clad optical fiber, so that the fluorescence receiving area can be further increased. The front-end lens 120 can use a superlens focusing, by controlling the geometry of the superlens array, so that the near-center region (i.e., the first array region 1223) realizes long-focus focusing, and the edge region outside the center region (i.e., the second array region 1224) realizes large numerical aperture, large space angle focusing, and the collection efficiency of the excited fluorescence is improved.

[0093] Exemplarily, different focusing modes can be realized by controlling the size of each superlens unit in the near-center region and the edge region outside the center region and the spacing between them. For example, as shown in Figure 5 , the size variation period of each superlens unit in the near-center region can be made smaller than that of the edge region outside the center region (i.e., the size difference of each superlens unit in the near-center region changes less with the spatial position, and the size difference of each superlens unit in the edge region outside the center region changes more with the spatial position), so that the edge region outside the center region has stronger focusing.

[0094] It should be noted that, Figure 5 The arrangement mode shown is only an example, and in practical applications, those skilled in the art can design the arrangement mode of the superlens array according to actual needs, and the embodiments of the present application do not specifically limit the arrangement mode of the superlens array.

[0095] It should be noted that the connection of each part of the imaging catheter in the embodiments of the present application can be realized by optical fiber fusion, adhesion and the like. The front-end lens can be realized by fusion, grinding, high-precision two-photon printing and photolithography and the like. The embodiments of the present application do not specifically limit this.

[0096] In summary, according to the multi-modal imaging catheter of the embodiments of the present application, by combining the intravascular multi-modal imaging mode of OCT imaging and fluorescence imaging, and using imaging light with similar wavelengths for the two modes, optical focusing is performed through the lens of the same imaging catheter, and because the wavelengths of the OCT imaging light and the fluorescence excitation light are similar, the focused light spot has better spatial matching degree, so that better spatially registered multi-modal images of blood vessels can be obtained, the difficulty of subsequent image processing is reduced, and the size of the imaging catheter does not need to be increased, so that it can be applied in smaller blood vessels, and the application range is wider.

[0097] Reference is made to the accompanying drawings Figure 6 which shows a structural schematic diagram of a multi-modal imaging system provided by an embodiment of the present application. As shown in Figure 6As shown, the multi-modal imaging system can include an OCT imaging module 200, a fluorescence imaging module 300, a combination and separation optical path module 400, and a catheter 100 as shown in the embodiments. Figures 1 to 5 The multi-modal imaging catheter 100 provided by the embodiments shown.

[0098] In the embodiments of the present application, the OCT imaging module 200 can be used to generate OCT imaging light; and can also be used to obtain OCT scattered light scattered by the OCT imaging light at the target position, and process the OCT scattered light to obtain an OCT imaging result.

[0099] Specifically, in combination with the drawings attached to the specification, Figure 7 The OCT imaging module 200 can include: an OCT light source 210 for generating OCT imaging light; an interference optical path 220 for interference processing of the obtained OCT scattered light to obtain interfered OCT scattered light; a photodetector 230 for converting the interfered OCT scattered light into an OCT imaging signal; and an OCT imaging processing module 240 for processing the OCT imaging signal to obtain an OCT imaging result.

[0100] Specifically, the OCT light source 210 can use a 1310nm OCT light source commonly used for intravascular imaging, that is, the wavelength of the OCT imaging light can be 1310nm. The interference optical path 220 can perform interference processing on the OCT imaging light generated by the OCT light source 210 to enhance it, and transmit the enhanced OCT imaging light to the combination and separation optical path module 400.

[0101] Specifically, the interference optical path 220 can also obtain the OCT scattered light obtained by the combination and separation optical path module 400 by separating the received light for imaging, and perform interference processing on the OCT scattered light to enhance it, and transmit the enhanced OCT scattered light to the photodetector 230. The photodetector 230 can convert the OCT scattered light into an electrical signal (i.e., an OCT imaging signal). The OCT imaging processing module 240 can obtain an OCT imaging result including blood vessel structure information by sampling the OCT imaging signal and reconstructing data. The OCT imaging result can include an OCT imaging image.

[0102] It should be noted that the detailed process of interference processing and obtaining the OCT imaging result can refer to the prior art, which will not be described here in the embodiments of the present application.

[0103] In the embodiments of the present application, the fluorescence imaging module 300 can be used to generate fluorescence excitation light and can also be used to obtain fluorescence emission light excited by the fluorescence excitation light at the target position, and process the fluorescence emission light to obtain a fluorescence imaging result.

[0104] Specifically, in combination with the drawings attached to the specification, Figure 7The fluorescence imaging module 300 can include: a fluorescence excitation light source 310 configured to generate fluorescence excitation light; a filtering light path 320 configured to filter the acquired fluorescence emission light to obtain filtered fluorescence emission light; a fluorescence detector 330 configured to convert the filtered fluorescence emission light into a fluorescence imaging signal; and a fluorescence imaging processing module 340 configured to process the fluorescence imaging signal to obtain a fluorescence imaging result.

[0105] Specifically, the fluorescence excitation light source 310 can adopt a 1550 nm short pulse laser light source, that is, the wavelength of the fluorescence excitation light can be 1550 nm. The filtering light path 320 can filter the fluorescence excitation light generated by the fluorescence excitation light source 310 and transmit the filtered fluorescence excitation light to the combination and separation light path module 400.

[0106] Specifically, the filtering light path 320 can also acquire the fluorescence emission light obtained by the combination and separation light path module 400 from the received light for imaging, filter the fluorescence emission light, and transmit the filtered fluorescence emission light to the fluorescence detector 330. The fluorescence detector 330 can convert the fluorescence emission light into a fluorescence imaging signal. The fluorescence imaging processing module 340 processes the fluorescence imaging signal to obtain a fluorescence imaging result including fluorescence intensity and lifetime information. The fluorescence imaging result can include a fluorescence imaging image. Since the wavelengths of the OCT imaging light and the fluorescence excitation light are similar, the focused light spots have good matching degree, and the obtained fluorescence imaging image and the OCT imaging image can be spatially registered images.

[0107] In one possible embodiment, the combination and separation light path module 400 can also separate the second harmonic signal, the third harmonic signal, etc. from the received light for imaging. The multi-modal imaging system can further include a harmonic imaging module configured to perform second harmonic imaging and third harmonic imaging according to the second harmonic signal and the third harmonic signal to obtain second harmonic imaging results and third harmonic imaging results.

[0108] It should be noted that the detailed processes of filtering, obtaining the fluorescence imaging result, and obtaining the second harmonic imaging result and the third harmonic imaging result can refer to the prior art, and will not be described here in detail.

[0109] In one possible embodiment, a pulse width preprocessing unit can also be arranged at the outlet of the fluorescence excitation light source 310 to perform pulse width preprocessing on the fluorescence excitation light generated by the fluorescence excitation light source 310 to pre-process the dispersion problem of the ultra-short pulse. The specific process of pulse width preprocessing can refer to the prior art, and will not be described here in detail.

[0110] In the embodiment of the present application, the combination and separation optical path module 400 can be used for combining the OCT imaging light and the fluorescence excitation light, and transmitting the combined OCT imaging light and fluorescence excitation light to the multi-modal imaging catheter 100.

[0111] In the embodiment of the present application, the multi-modal imaging catheter 100 can include the light beam transmission part 110 and the front-end lens 120 connected in sequence, and the front-end lens 120 can include the lateral reflection part 121 and the separation focusing part 122.

[0112] Specifically, the light beam transmission part 110 can be used for transmitting the combined OCT imaging light and fluorescence excitation light to the front-end lens 120, so that the front-end lens 120 focuses and irradiates the OCT imaging light and fluorescence excitation light on the imaging tissue at the target position.

[0113] Specifically, the lateral reflection part 121 can be used for changing the direction of the optical path, reflecting the OCT imaging light and fluorescence excitation light to the separation focusing part 122, and making the OCT imaging light and fluorescence excitation light exit laterally through the separation focusing part 122, so that the imaging catheter can perform annular scanning on the blood vessels. The separation focusing part 122 can use a low numerical aperture focusing mode to focus the OCT imaging light and fluorescence excitation light at the target position.

[0114] In the embodiment of the present application, the front-end lens 120 can also be used for collecting the light used for imaging. Specifically, the separation focusing part 122 can also be used for collecting the OCT scattered light scattered by the OCT imaging light at the target position, and using a low numerical aperture focusing mode to focus the OCT scattered light. The separation focusing part 122 can also use a high numerical aperture mode to focus at the target position, and collect the fluorescence emission light excited by the fluorescence excitation light at the target position. That is, the separation focusing part 122 can collect the light used for imaging including the OCT scattered light and the fluorescence emission light. The lateral reflection part 121 can also be used for changing the direction of the optical path, reflecting the light used for imaging collected by the separation focusing part 122 to the light beam transmission part 110, and the light used for imaging can be output to the combination and separation optical path module 400 by the light beam transmission part 110.

[0115] Specifically, the light beam transmission part 110 can also be used for transmitting the light used for imaging reflected by the lateral reflection part 121 to the combination and separation optical path module 400, and separating the OCT scattered light and the fluorescence emission light by the combination and separation optical path module 400.

[0116] Specifically, the combination and separation optical path module 400 can also obtain the light for imaging collected by the multi-modal imaging catheter 100, separate the OCT scattered light and the fluorescence emission light from the light for imaging, and transmit the OCT scattered light to the OCT imaging module 200 and transmit the fluorescence emission light to the fluorescence imaging module 300. The specific implementation principle of the combination and separation optical path module 400 for beam combining and separating can refer to the prior art, and the embodiments of the present application will not be described here.

[0117] In one possible embodiment, in combination with the description of the drawings Figure 8 The multi-modal imaging system can also include a motion control device 500 for controlling the motion of the multi-modal imaging catheter 100.

[0118] Specifically, the combined OCT imaging light and fluorescence excitation light obtained by the combination and separation optical path module 400 can be transmitted through the multi-modal imaging catheter 100, and the motion control device 500 can control the multi-modal imaging catheter 100 to move to the target position, so as to focus the combined OCT imaging light and fluorescence excitation light on the imaging tissue at the target position. Exemplarily, the motion control device 500 can include but is not limited to a rotating withdrawal device and the like.

[0119] In actual application, the motion control device 500 can realize optical efficient coupling and dynamic and static separation of the fixed end of the optical fiber and the rotating end of the optical fiber (including the multi-modal imaging catheter 100), and the device can further reduce the damage of short pulse width and high peak power laser to the coupling components through optical beam expansion.

[0120] It should be noted that other related contents in the embodiments of the present application can refer to the specific contents in the embodiments shown in the drawings, and the embodiments of the present application will not be described here. Figures 1 to 5

[0121] In summary, according to the multi-modal imaging system of the embodiments of the present application, the intravascular multi-modal imaging mode of combining OCT imaging and fluorescence imaging is used, and the two modes use imaging light with similar wavelengths, and optical focusing is performed through the same lens of the imaging catheter. Because the wavelengths of the OCT imaging light and the fluorescence excitation light are similar, the focused light spots have better spatial matching degree, so that the multi-modal images of the blood vessels with better spatial registration can be obtained, the difficulty of subsequent image processing is reduced, and the size of the imaging catheter does not need to be increased, so that the imaging catheter can be applied in smaller blood vessels and has a wider application range.

[0122] ​In addition, by adopting the separated focusing mode, the OCT imaging light and the fluorescence excitation light are focused by using the low numerical aperture focusing mode, which can not only ensure the OCT imaging depth, but also improve the fluorescence imaging depth, and by expanding the numerical aperture of the fluorescence detection part lens, the fluorescence emission light is collected and focused by using the high numerical aperture focusing mode, which can improve the collection efficiency of the fluorescence excited by the deep tissue, so that the fluorescence imaging can achieve the ideal imaging depth effect.

[0123] Although the present application has been illustrated and described with reference to certain preferred embodiments thereof, it should be understood by the skilled in the art that the foregoing is a further detailed description of the present application in connection with specific embodiments, and is not intended to limit the specific embodiments of the present application. It should be noted that, for those skilled in the art, a number of improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the scope of protection of the present application.

Claims

1. A multi-modal imaging catheter, comprising: The light beam transmission part and the front end lens are sequentially connected, and the front end lens comprises a lateral reflection part and a separate focusing part; The light beam transmission part is used for transmitting OCT imaging light and fluorescence excitation light to the front end lens, wherein the OCT imaging light and the fluorescence excitation light use near-infrared two-band imaging light with similar wavelengths; and for transmitting the light for imaging reflected by the lateral reflection part; The lateral reflection part is used for changing the direction of the light path, so that the OCT imaging light and the fluorescence excitation light are laterally emitted through the separate focusing part; and the light for imaging collected by the separate focusing part is reflected to the light beam transmission part; The separate focusing part is used for focusing the OCT imaging light and the fluorescence excitation light at a target position in a low numerical aperture mode; And for collecting the OCT scattered light scattered by the OCT imaging light through the tissue at the target position; The focusing at the target position is realized in a high numerical aperture mode, the fluorescence emission light excited by the fluorescence excitation light at the target position is collected to obtain the light for imaging; The fluorescence excitation light is two-photon fluorescence excitation light, and the fluorescence emission light is obtained by two-photon excitation at the target position.

2. The multi-modal imaging catheter of claim 1, wherein, The light beam transmission part comprises a first optical fiber with a double cladding; The core of the first optical fiber is used for transmitting the OCT imaging light and the fluorescence excitation light; The first cladding of the first optical fiber is wrapped on the outer sidewall of the core, and is used for transmitting the fluorescence emission light reflected by the lateral reflection part; The second cladding of the first optical fiber is wrapped on the outer sidewall of the first cladding, so that the fluorescence emission light is transmitted in the first cladding.

3. The multi-modal imaging catheter of claim 2, wherein, A light beam expansion part is further arranged between the light beam transmission part and the front end lens, and the light beam expansion part is used for expanding the OCT imaging light and the fluorescence excitation light transmitted by the light beam transmission part, and transmitting the expanded OCT imaging light and fluorescence excitation light to the front end lens.

4. The multi-modal imaging catheter of claim 3, wherein, The light beam expansion part comprises a second optical fiber, and the diameter of the second optical fiber is greater than or equal to the diameter of the first optical fiber.

5. The multi-modal imaging catheter of claim 1, wherein, The separate focusing part comprises a spherical mirror, and the spherical mirror comprises a first spherical surface region at a center position of the spherical mirror and a second spherical surface region around the first spherical surface region, wherein the focusing focal length of the first spherical surface region is greater than the focusing focal length of the second spherical surface region.

6. The multi-modal imaging catheter of claim 1, wherein, The separate focusing part comprises an array of superlenses, and the array of superlenses comprises a first array region at a center position of the array of superlenses and a second array region around the first array region, wherein the focusing focal length of the first array region is greater than the focusing focal length of the second array region.

7. A multi-modality imaging system, characterized by, The OCT imaging module, the fluorescence imaging module, the combined and separated light path module, and the multi-modal imaging catheter according to any one of claims 1-6 are combined; The OCT imaging module is used for generating OCT imaging light; and acquiring OCT scattered light scattered by the OCT imaging light through tissue at a target position, and processing the OCT scattered light to obtain an OCT imaging result; The fluorescence imaging module is configured to generate fluorescence excitation light, and acquire fluorescence emission light excited by the fluorescence excitation light at the target position, and process the fluorescence emission light to obtain a fluorescence imaging result. The combination and separation optical path module is configured to combine the OCT imaging light and the fluorescence excitation light, and transmit the combined OCT imaging light and fluorescence excitation light to the multi-modal imaging catheter; and acquire imaging light collected by the multi-modal imaging catheter, separate the OCT scattering light and the fluorescence emission light from the imaging light, and transmit the OCT scattering light to the OCT imaging module and transmit the fluorescence emission light to the fluorescence imaging module.

8. The system of claim 7, wherein, The OCT imaging module comprises: an OCT light source configured to generate OCT imaging light; an interference optical path configured to perform interference processing on the acquired OCT scattering light to obtain interference OCT scattering light; a photodetector configured to convert the interference OCT scattering light into an OCT imaging signal; an OCT imaging processing module configured to process the OCT imaging signal to obtain an OCT imaging result.

9. The system of claim 7, wherein, The fluorescence imaging module comprises: a fluorescence excitation light source configured to generate fluorescence excitation light; a filtering optical path configured to perform filtering processing on the acquired fluorescence emission light to obtain filtered fluorescence emission light; a fluorescence detector configured to convert the filtered fluorescence emission light into a fluorescence imaging signal; a fluorescence imaging processing module configured to process the fluorescence imaging signal to obtain a fluorescence imaging result.

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