CN114159029A

CN114159029A - Optical coherence tomography system and imaging catheter thereof

Info

Publication number: CN114159029A
Application number: CN202111444983.4A
Authority: CN
Inventors: 马腾; 孔瑞明; 张琪; 高磊; 宋宇霆; 陈焯权; 郑海荣
Original assignee: Shenzhen Institute of Advanced Technology of CAS
Current assignee: Shenzhen Institute of Advanced Technology of CAS
Priority date: 2021-11-30
Filing date: 2021-11-30
Publication date: 2022-03-11
Anticipated expiration: 2041-11-30
Also published as: CN114159029B

Abstract

The invention discloses an optical coherence tomography system and an imaging catheter thereof, wherein the imaging catheter comprises: the imaging lens is fixed in the shell and is opposite to the through hole of the shell; one end of the optical fiber is fixedly connected with the imaging lens; the protective sheath is arranged outside the optical fiber, the air bag is connected with the front end of the protective sheath, and an inflation port is arranged at the tail end of the protective sheath; the inner wall of the air bag is circumferentially provided with a plurality of rows of super lenses, each row of super lenses comprises a plurality of super lenses which are sequentially arranged along the length direction of the air bag, and the imaging lens is positioned in the air bag and between the rows of super lenses. The structural design of the imaging catheter can improve the resolution ratio on the premise of not reducing the focal depth.

Description

Optical coherence tomography system and imaging catheter thereof

Technical Field

The invention relates to the technical field of medical instruments, in particular to an optical coherence tomography system and an imaging catheter thereof.

Background

Optical Coherence Tomography (OCT) is an imaging technique that obtains the depth direction tomographic capability based on the principle of low Coherence interference, and reconstructs two-dimensional or three-dimensional images of the internal structure of biological tissues or materials by deflecting and scanning a light beam through a galvanometer. The OCT has the advantages of non-contact, non-invasion, high imaging speed (real-time dynamic imaging), high detection sensitivity and the like. At present, the OCT technology has been widely used in clinical diagnosis and scientific research. The traditional OCT system based on galvanometer scanning can only scan and image from outside the body, and in order to image some tissues which are far away in the body and difficult to reach, especially the pipeline structure, an endoscopic optical coherence tomography system using an optical fiber imaging catheter is gradually used.

The endoscopic optical coherence tomography system comprises an optical fiber slip ring and an endoscopic imaging catheter, wherein the endoscopic imaging catheter comprises an endoscopic probe, and the endoscopic probe usually comprises an optical fiber, a miniature imaging lens and a deflection reflector. The optical fiber slip ring and the imaging catheter are driven to rotate by the motor transmission platform so as to realize annular scanning imaging of endoscopic OCT. When the imaging catheter is inserted into a tissue to perform imaging, a protective sheath is generally sleeved outside the imaging catheter in order to avoid injuring the internal tissue during rotary scanning, and the protective sheath has good light transmittance and biocompatibility, so that the minimum rotation loss of the imaging catheter and the safety of the internal tissue can be ensured. Therefore, the endoscopic optical coherence tomography system has excellent application prospect in the fields of coronary artery imaging, intestinal tract imaging and pulmonary duct imaging.

When an optical coherence tomography system scans, the resolution of the system is inversely proportional to the focal depth, and in order to realize the imaging of a micro duct in a body, the diameter of an OCT endoscopic probe is generally about 1mm, so the sizes of a focusing lens and a reflecting mirror are generally smaller than 1mm, the micro size limits the numerical aperture of the focusing lens, and the resolution is sharply reduced due to the small numerical aperture. In the prior art, the resolution of the OCT system is generally improved by using a shorter wavelength and wider bandwidth light source, however, the use of a shorter wavelength light source results in a greatly increased scattering of light in the tissue, which severely limits the penetration of light and thus the imaging depth of the system in the tissue.

In summary, endoscopic optical coherence tomography systems have larger optical aberrations relative to extracorporeal optical coherence tomography systems, and the limited numerical aperture places greater constraints on the balance between OCT resolution and depth of focus. Therefore, how to improve the resolution of endoscopic OCT without reducing the depth of focus is a major development direction for the clinical development of endoscopic OCT systems.

Disclosure of Invention

In view of the foregoing, it is a first object of the present invention to provide an imaging catheter having a structural design that allows for increased resolution without reducing the depth of focus, and a second object of the present invention to provide an optical coherence tomography system including the above-described imaging catheter.

In order to achieve the first object, the invention provides the following technical scheme:

an imaging catheter, comprising:

the imaging lens is fixed in the shell and is opposite to the through hole of the shell;

one end of the optical fiber is fixedly connected with the imaging lens;

the protective sheath is arranged outside the optical fiber, the air bag is connected with the front end of the protective sheath, and an inflation port is arranged at the tail end of the protective sheath; the inner wall of the air bag is circumferentially provided with a plurality of rows of super lenses, each row of super lenses comprises a plurality of super lenses which are sequentially arranged along the length direction of the air bag, and the imaging lens is positioned in the air bag and between the rows of super lenses.

Preferably, in the above imaging catheter, a plurality of rows of the superlenses are uniformly distributed on the inner wall of the balloon along the circumferential direction thereof.

Preferably, in the above imaging catheter, the imaging lens is in a spherical crown shape.

Preferably, in the above imaging catheter, the optical fiber and the imaging lens are fixedly connected by fusion.

Preferably, in the above imaging catheter, the material of the protective sheath and the balloon is polyethylene;

the superlens is bonded to the inner wall of the balloon.

Preferably, in the above imaging catheter, at least a part of the balloon is cylindrical, the plurality of rows of the superlenses are disposed on an inner wall of a cylindrical portion of the balloon, and the plurality of rows of the superlenses are uniformly disposed along a circumferential direction of the cylindrical portion of the balloon.

Preferably, in the above imaging catheter, a torsion spring is further sleeved outside the optical fiber, and the torsion spring is driven to rotate so as to drive the housing and the imaging lens to rotate relative to the balloon.

Preferably, in the above imaging catheter, the optical fiber is a single mode optical fiber.

Preferably, in the above imaging catheter, the cross section of the superlens is cylindrical or square-cylindrical.

An optical coherence tomography system comprising an imaging catheter as claimed in any one of the above.

When the imaging catheter provided by the embodiment is applied, the light beam is emitted from the optical fiber and then irradiates to the imaging lens, the light beam is focused by the imaging lens, the focused light beam irradiates to the multiple rows of super lenses of the air bag after passing through the through hole of the shell, the shapes of the light beam can be adjusted to be approximately Gaussian-shaped light spots by the multiple rows of super lenses, the phase, the amplitude, the polarization and the shape of the light beam are adjusted in the process that the light beam passes through the multiple rows of super lenses, and then the light beam irradiates to tissues on the outer wall of the air bag. The balloon can be expanded by inflation to expand some of the conduits, avoiding the conduits from squeezing the housing and imaging lens.

In addition, due to the different diameters of the internal channels, the focal length of the imaging lens cannot be completely focused on various channels, and the imaging effect is sharply reduced after the imaging lens deviates from the focusing position due to the limitation of the focal depth. In the application, the size of the air bag can be adjusted, so that the position of the pipe wall of the pipeline is just at the focusing position of the imaging lens, and the optimal imaging effect is obtained. In other words, the diameter of a focusing light spot is not required to be reduced by reducing the numerical aperture, the resolution of the OCT can be improved under the condition that the imaging focal depth is not reduced by the super-lens array, the focal depth under the condition of large working distance can be improved by adjusting the size of the air bag, and the imaging resolution is prevented from being improved by reducing the imaging focal depth.

In the embodiment of the application, the superlens is arranged on the inner wall of the air bag, and is not required to be arranged inside the protective sheath, so that the installation size of the imaging catheter can be effectively reduced.

To achieve the second objective, the present invention further provides an optical coherence tomography system, which includes any one of the imaging catheters described above. Since the above-mentioned imaging catheter has the above-mentioned technical effects, the optical coherence tomography system having the imaging catheter should also have corresponding technical effects.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of an imaging lens, housing and fiber optic connection provided by an embodiment of the present invention;

fig. 2 is an overall schematic view of an imaging catheter provided by an embodiment of the invention.

In FIGS. 1-2:

1-imaging lens, 2-shell, 3-optical fiber, 4-torsion spring, 5-air bag, 6-superlens, 7-protective sheath, 8-inflation inlet.

Detailed Description

As described in the background, the endoscopic optical coherence tomography is widely used in the in vivo imaging technology, and the geometric structural morphology of the duct tissue can be acquired by integrating the optical imaging element in the catheter and extending into the duct for imaging. Optical coherence tomography provides high resolution tomographic images, but its imaging depth is relatively shallow, typically only 1-2mm penetration depth in tissue. The pipe diameters of the pipelines in the human body are different, and the diameters are approximately distributed between 0.5 mm and 8 mm. Since the optical elements of an optical coherence tomography system are very small in diameter, the numerical aperture is usually small. In order to obtain a smaller focused light spot to improve the lateral resolution, the working distance of the imaging probe, i.e. the distance from the probe surface to the focal point, is generally adjusted to be short, however, the extremely short working distance improves the resolution, but the focal depth range is small, and the imaging range is greatly sacrificed, so that tissues with a large pipe diameter are difficult to clearly image, thereby limiting the clinical application of endoscopic OCT.

It is a first object of the present invention to provide an imaging catheter having a structural design that allows for improved resolution without a reduction in depth of focus, and a second object of the present invention to provide an optical coherence tomography system including the above-described imaging catheter.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left" and "right", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the positions or elements referred to must have specific orientations, be constructed in specific orientations, and be operated, and thus are not to be construed as limitations of the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Referring to fig. 1-2, the present invention provides an imaging catheter including a housing 2, an imaging lens 1, an optical fiber 3, a protective sheath 7, and a balloon 5. Wherein the housing 2 has a through hole. The imaging lens 1 is fixed in the housing 2, and the imaging lens 1 is opposed to the through hole of the housing 2.

One end of the optical fiber 3 is fixedly connected with the imaging lens 1, the other end of the optical fiber 3 can be connected with the laser and the optical receiver through the coupler, light emitted by the laser enters the optical fiber 3 after passing through the coupler, and light returned by the optical fiber 3 enters the optical receiver through the coupler. The laser, the optical receiver and the coupler may be of any conventional structure, and are not limited thereto.

The protective sheath 7 is sleeved on the outer side of the optical fiber 3, the air bag 5 is connected with the front end of the protective sheath 7, an inflation inlet 8 is formed in the tail end of the protective sheath 7, and the inflation inlet 8 is inflated or sucked to achieve bulging or contraction of the air bag 5. The inner wall of the air bag 5 is provided with a plurality of rows of super lenses 6 along the circumferential direction, and each row of super lenses 6 comprises a plurality of super lenses 6 which are sequentially arranged along the length direction of the air bag 5. The first end of the balloon 5 is connected with the protective sheath 7, the second end of the balloon 5 is away from the protective sheath 7, and the length direction of the balloon 5 is the direction extending from the first end to the direction away from the protective sheath 7, or the length direction of the balloon 5 is the direction extending from the first end to the second end. After the balloon 5 is deployed in a plane, a plurality of superlenses 6 are in a rectangular array. The balloon 5 and the protective sheath 7 may be formed as a single body, so that the balloon 5 and the protective sheath 7 may be formed integrally.

The imaging lens 1 is located within the balloon 5 and the imaging lens 1 is located between rows of superlenses 6. The housing 2 may be located entirely within the air-bag 5 or the housing 2 may be located partially within the air-bag 5.

The superlens 6 is a diffractive optical element, and can realize far-field superdiffraction limit focusing and imaging of pure optics. Compared with the traditional optical lens, the planar super lens has the advantages of strong focusing capacity, compact structure, flexible design, convenience in integration and the like. The superlens 6 can adjust and control the incident light wave at will on the parameters of phase, amplitude, spectrum, polarization, etc., thereby improving the quality of the incident light beam.

When the imaging catheter provided by the above embodiment is applied, the light beam is emitted from the optical fiber 3 and then irradiates to the imaging lens 1, the light beam is focused by the imaging lens 1, the focused light beam passes through the through hole of the housing 2 and then irradiates to the multiple rows of the superlenses 6 of the balloon 5, the shapes of the light beam can be adjusted by the multiple rows of the superlenses 6 to be approximately gaussian-shaped light spots, the phase, amplitude, polarization and light beam shape of the light beam are adjusted in the process that the light beam passes through the multiple rows of the superlenses 6, and then the light beam irradiates on the tissue on the outer wall of the balloon 5. The balloon 5 can be expanded by inflation to expand some of the conduits to avoid the conduits from squeezing the housing 2 and imaging lens 1. The light beam is irradiated to the tissue on the outer wall of the air bag 5 and then returns, and the returned light finally enters the light receiver after passing through the imaging lens 1 and the optical fiber 3.

In addition, the focal length of the imaging lens 1 cannot be completely focused on various conduits due to the different diameters of the conduits in the body, and the imaging effect is sharply reduced after deviating from the focusing position due to the limitation of the focal depth. In the application, the size of the air bag 5 can be adjusted, so that the position of the pipe wall of the pipeline is just at the focusing position of the imaging lens 1, and the optimal imaging effect is obtained. In other words, the diameter of a focusing light spot is not required to be reduced by reducing the numerical aperture, the resolution of the OCT can be improved without reducing the imaging focal depth by the superlens 6 array, the focal depth under the condition of a large working distance can be improved by adjusting the size of the air bag 5, and the imaging resolution is prevented from being improved by reducing the imaging focal depth.

In the embodiment of the application, the superlens 6 is arranged on the inner wall of the air bag 5 and is not required to be arranged inside the protective sheath 7, so that the installation size of the imaging catheter can be effectively reduced.

Preferably, in a particular embodiment, the rows of superlenses 6 are evenly distributed along the circumference of the inner wall of the balloon 5. The plurality of superlenses 6 in each column are also uniformly distributed, so that the imaging effect can be further improved.

As shown in fig. 2, the imaging lens 1 may have a spherical crown shape. In particular, the height of the spherical cap may be between a quarter diameter and a half diameter. By adopting the spherical crown lens, a plurality of optical elements do not need to be spliced, so that loss and interference in OCT imaging can be effectively reduced, and the imaging quality is integrally improved. The light beam irradiated onto the bottom surface of the spherical-crown-shaped imaging lens 1 is totally reflected, deflected, and then focused by the spherical surface.

Preferably, the optical fiber 3 and the imaging lens 1 may be fixedly connected by welding, and of course, the optical fiber 3 and the imaging lens 1 may also be bonded, which is not limited herein.

The protective sheath 7 is made of polyethylene, which has low strength, hardness and rigidity, high ductility and impact strength, and low friction. The material of the airbag 5 may be polyethylene. Of course, the protective sheath 7 and the balloon 5 may be made of other materials, and are not limited herein.

At least part of the air bag 5 is cylindrical, a plurality of rows of super lenses 6 are arranged on the inner wall of the cylindrical part of the air bag 5, and the plurality of rows of super lenses 6 are uniformly arranged along the circumferential direction of the cylindrical part of the air bag 5. The center line of the cylindrical portion of the airbag 5 is provided along the longitudinal direction of the airbag 5. Of course, the balloon 5 may also have other shapes, such as ellipsoidal, spherical, etc.

The housing 2 may be a metal shell, and may be made of stainless steel, which is not limited herein.

In a particular embodiment, the superlens 6 may be bonded to the inner wall of the balloon 5. Or the superlens 6 and the inner wall of the balloon 5 may be welded or otherwise connected.

As shown in fig. 1, in order to rotate the imaging lens 1 and the housing 2 to realize annular scanning imaging, a torsion spring 4 is further sleeved outside the optical fiber 3, and the torsion spring 4 is driven to rotate to drive the housing 2 and the imaging lens 1 to rotate relative to the air bag 5. Specifically, the torque spring 4 is driven to rotate, and the torque spring 4 rotates the imaging lens 1 and the housing 2.

The optical fiber 3 can be a single-mode optical fiber, which has a wide transmission band and a longer transmission distance and is suitable for an optical coherence tomography system. Of course, the optical fiber 3 may be a multimode optical fiber, and is not limited thereto.

The superlens 6 may be a cylindrical or square column, and two opposite end faces of the superlens 6 are flat surfaces. Of course, the superlens 6 may have other shapes, and is not limited herein.

Based on the imaging catheter provided in the above embodiment, the invention further provides an optical coherence tomography system, which includes any one of the imaging catheters in the above embodiments. Since the optical coherence tomography system employs the imaging catheter in the above embodiments, please refer to the above embodiments for the beneficial effects of the optical coherence tomography system.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Claims

1. An imaging catheter, comprising:

the imaging device comprises a shell (2) with a through hole and an imaging lens (1) fixed in the shell (2), wherein the imaging lens (1) is opposite to the through hole of the shell (2);

the optical fiber (3), one end of the said optical fiber (3) is fixedly connected with the said imaging lens (1);

the optical fiber protection device comprises a protection sheath (7) and an air bag (5), wherein the protection sheath (7) is sleeved on the outer side of the optical fiber (3), the air bag (5) is connected with the front end of the protection sheath (7), and the tail end of the protection sheath (7) is provided with an inflation inlet (8);

the inner wall of the air bag (5) is circumferentially provided with a plurality of rows of super lenses (6), each row of super lenses (6) comprises a plurality of super lenses (6) which are sequentially arranged along the length direction of the air bag (5), and the imaging lens (1) is positioned in the air bag (5) and positioned between the rows of super lenses (6).

2. The imaging catheter according to claim 1, characterized in that a plurality of rows of said superlenses (6) are evenly distributed along the circumference of the balloon (5) on its inner wall.

3. Imaging catheter according to claim 1, characterized in that the imaging lens (1) is of spherical crown shape.

4. Imaging catheter according to claim 1, characterized in that the optical fiber (3) is fixedly connected to the imaging lens (1) by means of fusion.

5. The imaging catheter according to claim 1, characterized in that the protective sheath (7) and the balloon (5) are made of polyethylene;

the superlens (6) is bonded with the inner wall of the air bag (5).

6. The imaging catheter according to claim 1, wherein the balloon (5) is at least partially cylindrical, a plurality of rows of the superlenses (6) are arranged on the inner wall of the cylindrical portion of the balloon (5), and the plurality of rows of the superlenses (6) are uniformly arranged along the circumference of the cylindrical portion of the balloon (5).

7. The imaging catheter according to claim 1, wherein a torsion spring (4) is further sleeved on the outer side of the optical fiber (3), and the torsion spring (4) is driven to rotate so as to drive the housing (2) and the imaging lens (1) to rotate relative to the balloon (5).

8. The imaging catheter according to claim 1, characterized in that the optical fiber (3) is a single mode optical fiber.

9. The imaging catheter according to claim 1, characterized in that the cross section of the superlens (6) is cylindrical or square cylindrical.

10. An optical coherence tomography system comprising an imaging catheter according to any of claims 1 to 9.