Capsule endomicroscope for acquiring images of the surface of a hollow organ

Abstract

A capsule endomicroscope has a predetermined axial length and a diameter smaller than the axial length. The endomicroscope can acquire images of a surface of a hollow organ, and includes a microscopic image acquisition assembly having an optical axis oriented in a radial direction of the endomicroscope to acquire microscopic images of a section of the surface of a hollow organ present in a predetermined image acquisition area on a radial outer surface of the endomicroscope through a housing of the endomicroscope that has sectionally light-transparent material. A light source emits light rays in a radial direction through the light-transparent material of the housing during image acquisition. The light source and the light-transparent material of the housing located between the light source and the predetermined image acquisition area are interconnected to each other such that no refraction interface exists between the light source and the image acquisition area.

Claims

1. A capsule endomicroscope having a predetermined axial length and a diameter which is smaller than the axial length the capsule endomicroscope being adapted to acquire images of a surface of a hollow organ, the capsule endomicroscope comprising: a microscopic image acquisition assembly having an optical axis orientated in a radial direction of the capsule endomicroscope in a way to acquire microscopic images of a section of the surface of the hollow organ present in a predetermined image acquisition area on a radial outer surface of the capsule endomicroscope through a housing of the capsule endomicroscope consisting of at least sectionally light-transparent material, and a light source adapted to emit light rays in the radial direction of the capsule endomicroscope through the light-transparent material of the housing during image acquisition, wherein light-transparent material of the housing is located between the light source and the predetermined image acquisition area, and wherein the light source and the light-transparent material of the housing are interconnected to each other such that refraction interfaces between the light source and the predetermined image acquisition area are avoided, wherein the light source is directly incorporated or embedded or molded into a separate component of a light-transparent material and said separate component is directly incorporated or embedded or molded into the light-transparent material of the housing, and wherein the light-transparent material of the separate component and the light-transparent material of the housing have essentially the same refractive index.

2. The capsule endomicroscope according to claim 1, wherein the light source is directly incorporated or embedded or molded into the light-transparent material of the housing.

3. The capsule endomicroscope according to claim 1, wherein the microscopic image acquisition assembly is arranged in a lumen provided within the housing or inside the light-transparent material of the housing wherein a separate distortion prevention component is provided above the microscopic image acquisition assembly when seen in the direction of the optical axis, the separate distortion prevention component is interconnected with the light-transparent material of the housing to form an upper boundary of the lumen when seen in the direction of the optical axis and is adapted to prevent any refraction interface from arising at the boundary between a fluid present in the lumen and the distortion prevention component.

4. The capsule endomicroscope according to claim 3, wherein the distortion prevention component has on its one side forming an upper boundary of the lumen a predetermined surface structure being different than a structure of an inside surface of the housing and being adapted to reduce refraction at a surface of the distortion prevention component.

5. The capsule endomicroscope according to claim 1, wherein a center of gravity of the capsule endomicroscope is displaced from a geometric center point of the capsule endomicroscope.

6. The capsule endomicroscope according to claim 5, wherein the center of gravity of the capsule endomicroscope is displaced from the geometric center point of the capsule endomicroscope towards a position of the image acquisition area on the radial outer surface of the capsule endomicroscope.

7. The capsule endomicroscope according to claim 1, further comprising a recess at the radial outer surface of the capsule endomicroscope, a position of said recess at least in part coinciding with a position of the image acquisition area on the radial outer surface of the capsule endomicroscope.

8. The capsule endomicroscope according to claim 1, further comprising a proximity detection assembly configured to detect the presence of an object in the immediate proximity of the image acquisition area and, if said detection result is positive, activate the microscopic image acquisition assembly and the light source accordingly.

9. The capsule endomicroscope according to claim 1, further comprising a macroscopic context image acquisition assembly adapted to acquire macroscopic images of larger surroundings of the capsule endomicroscope, simultaneously with an image acquisition operation of the microscopic image acquisition assembly.

10. The capsule endomicroscope according to claim 1, wherein the light source is interconnected with the light-transparent material of the housing by casting or moulding or grouting or potting or press-fitting or embedding or directly via an intermediate coupling fluid having essentially the same refractive index as the light-transparent material of the housing.

11. The capsule endomicroscope according to claim 1, wherein the light-transparent material of the housing constitutes an outer layer of the housing of the capsule endomicroscope.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) Further features and advantages of the present invention become apparent from the following description of presently preferred embodiments.

(2) In the figures,

(3) FIG. 1 shows an embodiment of a capsule endomicroscope according to the present invention in which the microscopic image acquisition assembly is a contact imaging unit, and with a data processing unit, a data storage unit and an energy source.

(4) FIG. 2 shows an embodiment of a capsule endomicroscope according to the present invention with a contact imaging unit and a proximity detection assembly/contact sensor, and with a macroscopic context image acquisition assembly/lumen imaging unit and with a data processing unit, a telemetry unit and an energy source.

(5) FIG. 3 shows a capsule endomicroscope according to the present invention, especially disclosing the constructive features of the microscopic image acquisition assembly/contact imaging unit.

(6) FIGS. 4a and 4b are detailed views of the features of the microscopic image acquisition assembly/contact imaging unit in an embodiment of a capsule endomicroscope adapted for contact imaging of tissue with an essentially smooth tissue surface. FIG. 4a shows a contact imaging unit without a separate component. FIG. 4b shows a contact imaging unit with a separate component.

(7) FIG. 5 shows a detailed view of the features of the microscopic image acquisition assembly/contact imaging unit, in an embodiment of a capsule endomicroscope especially adapted for contact imaging of tissue with an essentially smooth tissue surface.

(8) FIG. 6 shows a detailed view of the features of the microscopic image acquisition assembly/contact imaging unit in an embodiment of a capsule endomicroscope especially adapted for contact imaging of tissue with a three-dimensionally structured tissue surface.

(9) FIG. 7 shows a detailed view of the construction features of the microscopic image acquisition assembly/contact imaging unit and the capturing of a three-dimensionally structured tissue surface.

(10) FIG. 8 shows a capsule endomicroscope according to the present invention, in which the center of gravity and the geometric center point of the capsule endomicroscope are indicated.

DETAILED DESCRIPTION

(11) As shown in FIG. 1, a capsule endomicroscope 15 according to the present invention comprises a contact imaging unit 17 as an image acquisition assembly, a data processing unit 18, a data storage unit 22 and a power source 20.

(12) FIG. 2 shows another capsule endomicroscope 15 according to the present invention comprising the contact imaging unit 17, the data processing unit 18 as well as a telemetry unit 16, a contact sensor unit 19 as a proximity detection assembly and a lumen imaging unit 21 as a context image acquisition assembly.

(13) Other embodiments of the invention can have different combination of features such as the embodiment shown in FIG. 1 with a telemetry unit instead of a data storage unit, or the embodiment shown in FIG. 2 without a proximity detection assembly/contact sensor, or the embodiment shown in FIG. 1 with a proximity detection assembly/contact sensor. Other such combinations are also possible.

(14) As shown in FIG. 3, an outer housing separates the interior 11 of the capsule endomicroscope 15 from the surroundings of the capsule endomicroscope. On the outer housing is the outer capsule surface 9.

(15) Further constructive details of the contact imaging unit 17 become apparent from FIG. 4, in which a detailed view (as indicated by the numeral 14) of the contact imaging unit 17 is shown.

(16) According to this embodiment, the light source/illumination means of the contact imaging unit 17 preferentially contains one or more conventional LEDs 29 that are connected with an optically transparent material 1 forming the outer layer of the outer housing of the capsule endomicroscope 15 in such a way, that the optical refractive interface between the optically transparent material 1 of the housing of the capsule 15 and the optically transparent material 2 of the conventional LED 29 essentially disappears or is dissolved.

(17) This is achieved through the connection of two materials with a similar refractive index preferentially through a form fitting mechanism and/or casting technique. To indicate this dissolution of the refractive interface between said materials/components, in FIGS. 4a, 4b, 5, 6 and 7, the line between the optically transparent material 1 of the housing of the capsule endomicroscope 15 and the optically transparent material 2 of the conventional LED 29 is shown as a dashed line.

(18) Each LED 29 comprises a LED-chip 4 that is mounted onto a substrate material 3 and that is surrounded by and connected with an optically transparent material 2. The optically transparent material 2 of the LED 29 and the optically transparent material 1 of the housing of the capsule endomicroscope 15 are selected in such a way that light emitted from the LED-chip 4 travels exclusively through solid material components preferentially connected to each other by a form-locking mechanism from the LED-chip 4 to the image acquisition area 12 on the capsule surface 9 of the outer housing of the capsule endomicroscope 15.

(19) The outer housing can be formed of only a single layer of material or of multiple layers and separates the interior 11 of the capsule endomicroscope 15 from the surroundings.

(20) In the embodiment according to FIG. 4, the two LED-chips 4 are embedded into the most peripheral layer 1 of the outer housing of the capsule endomicroscope 15 that separates the outer surface 9 of the capsule endomicroscope 15 from the interior 11 of the capsule endomicroscope 15.

(21) The optically transparent material 1 is a solid material and forms a part of the capsule endomicroscope surface 9, especially in the image acquisition area 12. The optically transparent material 1 may be a material composite, wherein optical characteristics, especially refractive indices, within the material composite are essentially equal or constant along the entire path of light travelling from the image acquisition area 12 to the image acquisition assembly 17 and/or to an optical sensor contained within the image acquisition assembly. This helps to prevent distortions or scattering of light at the interface between different materials of differing refractive indices which may reduce the quality of the optical imaging.

(22) In order to achieve high biocompatibility, chemical resistance and/or surface properties of the capsule endomicroscope, a special housing/coating may be deposited on the outer housing of the capsule endomicroscope. This housing/coating may be Parylene.

(23) In such a case the very thin layer of the optical transparent material Parylene may be of a dimension of 10 to 20 micrometers, which does not cause a reduction in the quality of illumination and/or image acquisition even in case of a difference in refractive index between the housing material and the optically transparent material 1. As the layer of Parylene is very thin, a negative impact upon the optical characteristics of the material of the capsule endomicroscope is minimized.

(24) The LEDs 29 are mounted onto a layer of substrate material 5, in which like in an electronic conductor plate the electrical circuits for the operation of the LEDs 29 are integrated. The mounting of the LEDs 29 onto the substrate material 5 can occur through gluing or bonding (direct mounting of the LEDs) or through welding/soldering (mounting of the LEDs as conventional LEDs comprising welding terminals). The LEDs 29 form the light source/illumination means in this embodiment.

(25) In the following, the image acquisition assembly/optical sensor of the contact imaging unit 17 is described.

(26) In this embodiment, the image acquisition assembly is a camera 26. The camera 26 comprises an optical module 6 and an image sensor 7. The geometric configuration and arrangement of the optical module 6 and the image sensor 7 generates an image acquisition area 12 of a predetermined size on the surface 12 of the capsule endomicroscope 15.

(27) The camera 26 is arranged within the capsule endomicroscope 15, so that the image acquisition area 12 is created on the capsule surface 9 in an image acquisition area of a desired size, for example 11 millimeter.

(28) In this image acquisition area 12 a tissue surface 23 adjacent to the capsule endomicroscope surface 9 can be detected and captured. It increases imaging quality if the tissue surface 13 is immediately adjacent and actually physically contacts the image acquisition area 12.

(29) In order to increase the efficiency of the light source/illumination means it is advantageous to position the light source/illumination means as close as possible to the imagining area 12 of the capsule surface 9.

(30) In order to simultaneously determine the desired size of the image acquisition area 12 and in order to avoid light emitted from the light source directly being captured by the camera 26, the camera 26 is distanced from the capsule endomicroscope surface 9 further away than the light source/illumination means, i.e. the LEDs 29. For this purpose, the camera 26 can be positioned in a recess or lumen 13 within the substrate material 5, which encases the lumen 13 accommodating the camera 26.

(31) The camera 26 is mounted onto a substrate material 8 arranged closer to a central longitudinal axis of the capsule endomicroscope 15 in radial direction than the substrate layer 5 in which the lumen 13 is formed. In other words, the layer of substrate material 8 is located closer to the interior of the capsule 15 and hence less peripheral than the layers of substrate material 5 and optically transparent material 1.

(32) The lumen 13 around the camera 26 can be filled with a fluid or solid. This solid material can also be part of the optically transparent material 1.

(33) Preferentially, the lumen 13 surrounding the camera 26 is filled with air. The light travelling between the camera 26 and the image acquisition area 12 in this case passes an optical refractive interface on its path from the image acquisition area 12 at the surface 9 of the capsule endomicroscope 15 and the lumen 13 containing the air.

(34) This optical refraction interface is generated through a high difference in refractive indices of, for example, 1.0 for air and 1.5 for the optically transparent material 1. Also, the requirements for the quality of the surface of the boundary surface 10 at the boundary between the air in the lumen 13 and the optically transparent material 1 are high, because irregularities of the surface forming the boundary surface 10 can lead to distortions and reductions in quality of the imaging.

(35) In order to ensure a high quality of the surface forming the boundary surface 10 during the manufacture of the capsule endomicroscope 15 and to prevent the arising of a refraction interface, a distortion prevention component 28, e.g. a component of optically transparent material, can be arranged between the lumen 13 surrounding the camera 26 and the optically transparent material 1.

(36) The distortion prevention component 28 can be a component of a polymer material of a defined and known surface quality and structure as well as of a certain desired refractive index. A capsule endomicroscope 15 with a contact imaging unit 17 comprising a distortion prevention component 28 is shown in FIG. 4b.

(37) The distortion prevention component 28 can form the boundary of the lumen 13 on that side of the lumen 13 that is closest to the image acquisition area 12. The surface of the distortion prevention component can be adjusted to have certain defined characteristics, e.g. to be very smooth and/or regular so that blurring and distortions arising at the interface between the distortion prevention component 28 and the lumen 13 are minimized.

(38) Such a distortion prevention component 28 serves to ensure a sufficient quality of the surface forming the boundary surface 10 without the need for using a casting technique which causes increased complexity, increased costs and limited reproducibility.

(39) In this embodiment, the distortion prevention component 28 is a component of optically transparent material and forms part of the optically transparent material 1. This causes the boundary surface between the distortion prevention component 28 and the rest of the optically transparent material 1 to dissolve. This effect is indicated in FIG. 4b by a dashed line between the distortion prevention component 28 and the optically transparent material 1.

(40) For some applications of the capsule endomicroscope, it is advantageous if the contour of the endomicroscope surface 9 in the image acquisition area 12 essentially follows the contour of the endomicroscope surface along the rest of the capsule endomicroscope 15. In other words, in such an embodiment, the surface of the capsule endomicroscope is essentially smooth and capsule-like without any projections or recesses. Such a capsule endomicroscope 15 is especially suitable for capturing tissue with a smooth surface.

(41) As shown in FIG. 5, a smooth tissue surface 23 of tissue 30 located in direct proximity to the capsule endomicroscope surface 9 in the image acquisition area 12 can be illuminated by the light source and captured by the camera 26.

(42) As both the surface 9 of the capsule endomicroscope 15 and the tissue surface 23 are essentially flat and smooth, direct contact can be established between the tissue surface 23 and the image acquisition area 12. This configuration is especially advantageous for capturing tissue surface in the esophagus.

(43) If a tissue with a three-dimensionally structured surface is to be captured, the capsule endomicroscope 15 can additionally be equipped with a recess 27 as shown in FIGS. 6 and 7.

(44) The image acquisition area 12 preferentially extends within the boundaries of this recess 27. The recess 27 serves to contain structures 25 present at the tissue surface and is configured in such a way that these structures 25 can enter into the space generated by the recess 27 and thereby re-adopt their physiological three-dimensional configuration in a state in which the capsule endomicroscope 15 is pressed against the tissue 30.

(45) For example, the recess 27 allows intestinal villi of a small intestine to adopt their physiological configuration during the image acquisition process. With conventional capsule endomicroscopes the intestinal villi are pressed flat into an abnormal position during image acquisition which does not allow for visualizing the intestinal villi in their native configuration. This makes it impossible to detect pathologies in the three-dimensional configuration or shape of the intestinal villi, as present e.g. in celiac disease.

(46) During the use of the capsule endomicroscope the small intestine can be filled with a water-like liquid, for example polyethylene glycol. In this case the spaces 24 between the endomicroscope surface 9 and the tissue surface 23 are filled with a clear liquid characterized by a significantly smaller difference in refractive index relative to the optically transparent material 1, than for example air.

(47) In this case the refractive interface formed at the capsule endomicroscope surface 9 and the polyethylene glycol has less negative impact on the illumination and image acquisition than an interface between the surface 9 and air would have. This is indicated in FIG. 7 by a dashed line of the capsule surface 9 between the optically transparent material 1 and the spaces 24.

(48) Additionally, the capsule endomicroscope 15 can comprise a contact sensing unit configured to detect the presence of tissue 30 in the direct proximity of the contact imaging unit 17/image acquisition area 12.

(49) This serves to prevent image acquisition in a state in which no tissue 30 is present in the image acquisition area 12/capsule surface 9 in a desired proximity or in direct contact with the image acquisition area 12/capsule surface 9. This is especially advantageous in order to avoid energy usage in times where no tissue is close enough to the capsule endomicroscope in order to generate useful data.

(50) Further additionally, the capsule endomicroscope 15 may comprise a context image acquisition assembly/lumen imaging unit 21, that captures the lumen of a hollow organ, especially at that point in time at which also the contact imaging unit 17 captures close-up images of the tissue surface.

(51) This serves the purpose to provide a context to the images captured by the contact imaging unit 17 in order to improve the quality of diagnosis. For example, the absence of intestinal villi is entirely normal in some sections of the intestinal tract whereas in other sections of the intestinal tract such an absence of intestinal villi is strongly indicative of a disorder.

(52) As shown in FIG. 8, the center of gravity 31 of the capsule 15 need not coincide with the geometric center point 32 of the capsule 15. The center of gravity 31 of the capsule 15 is preferentially shifted from the geometric center point 32 of the capsule endomicroscope 15 in the direction towards the contact imaging unit 17.

(53) This leads to a tilted orientation of the capsule 15 in space, in which that side of the capsule endomicroscope 15 on which the contact imaging unit 17 arranged is brought into direct proximity or into direct contact with the tissue surface 23.

(54) This can be achieved by positioning components of high density (for example batteries) on a side of the capsule endomicroscope 15 which also comprises the contact imaging unit 17 or by creating spaces of low density (for example air) at that side of the capsule endomicroscope 15 opposite to the contact imaging unit 17.

(55) The geometric center point 32 of the capsule endomicroscope 15 coincides with the center of gravity 31, when the capsule endomicroscope 15 completely consists of material of equal and constant density.