Optoelectronic probe for the analysis of tissues located inside the human body

Abstract

An optoelectronic probe for the analysis of tissues located inside the human body comprising a flexible external tubular protection element (2) configured to be inserted with its front end portion (3) in a tissue (4) to be subjected to analysis, an internal sleeve (6) sliding axially inside the protection tubular element (2) and provided with a front end portion (6-a) which is available between a rest position in which it is contained in the tubular element (2) and a use position in which it projects from the tubular element (2). The internal sleeve has: a first channel (7) housing a first optical fibre (8) configured to supply an excitation signal to the tissue; a second channel (11) housing a second optical fibre (12) configured to receive a response signal coming from the tissue; a third channel (15) configured to feed a fluid containing preferably nano-particles to the tissue (4); and a fourth channel (17) housing an expandable element (17) configured to project, in use, from the end (6-a) of the sleeve (6) when it is arranged in the rest position to expand and be arranged in contact with the internal walls of the external tubular protection element (6) acting as a plug and separating the end (6-a) of the sleeve ( 6) from the tissue (4).

Description

[0001] "OPTOELECTRONIC PROBE FOR THE ANALYSIS OF TISSUES LOCATED INSIDE

[0002] THE HUMAN BODY"

[0003] Technical Field

[0004] The present invention relates to an optoelectronic probe for the analysis of tissues located inside the human body .

[0005] Background of the invention

[0006] Document US5615673A discloses a method for measuring the concentration of a gas (oxygen or carbon dioxide) dissolved in blood comprising the steps of : irradiating the blood with laser radiation having a wavelength such that Raman scattering occurs for such gas; collecting Raman scattered light from the dissolved gas; and detecting the Raman scattered light collected from the dissolved gas in response to the laser radiation .

[0007] Document W02010083484A2 discloses a Raman spectrographic system for measuring Raman spectra of a tissue, the system comprises : a Raman spectrographic probe having an elongated handle extending from a first end to a second end and a contact tip extending over a predefined distance from the first end; a Raman spectrograph including a detector; a first laser source adapted to produce a first laser radiation at a predefined first wavelength; a first excitation fibre coupled to the laser source and extending as far as the first end of the Raman spectrographic probe and adapted to transfer the laser radiation to the first end; a plurality of emission fibres coupled to the Raman spectrograph and extending as far as the first end of the probe of the Raman spectrograph. The system of W02010083484A2 can be used by a technician or a physician to detect a pathologic tissue by placing the tip of the probe toward the tissue to be examined.

[0008] This system only allows a superficial analysis of the tissue and does not allow the access to portions of a tissue located inside the human body and belonging to an internal organ (e . g . liver, kidney, etc . ) .

[0009] Aim of the present invention .

[0010] Aim of the present invention is to realize a probe capable of examining tissues located inside the human body allowing the identification of the type of cells of the tissue in which the probe is inserted . In particular, this probe is able to detect structural differences in tissue composition . The probe of the present invention can be used, for example, to identify a variety of type of tumour pathologies by providing a rapid diagnosis .

[0011] The preceding aim is achieved by the present invention in that it relates to an optoelectronic probe of the type described in Claim

[0012] 1 .

[0013] Brief description of the drawings

[0014] The invention will now be shown with reference to the accompanying drawings which represent a non-limiting embodiment in which :

[0015] Figure 1 shows in perspective view an optoelectronic probe realized according to the dictates of the present invention;

[0016] Figure 2 shows a longitudinal section of the probe realized according to the plane indicated in Figure 1 and arranged in a first operating position; Figure 3 shows a longitudinal section of the probe realized according to the plane indicated in Figure 1 and arranged in a second operating position;

[0017] Figure 4 shows a longitudinal section of the probe realized according to the plane indicated in Figure 1 and arranged in a third operating position; and

[0018] Figure 5 schematically shows a system using the probe realized according to the present invention .

[0019] Preferred embodiment example .

[0020] In Figure 1, number 1 denotes an optoelectronic probe for the analysis of tissues realized according to the present invention .

[0021] The probe 1 comprises a flexible external tubular protection element 2 (bundle) provided with a front end portion 3 configured to be inserted into a fabric 4 (see Figure 4 ) to be subjected to analysis and provided with a rear portion which is connected with a handling system 5 of known type and formed by parts available on the market (such as stepper motors, e . g . schematically and partially represented in Figure 1 ) adapted to achieve the axial movement of the tubular element 2 with opposite directions (see arrows F

[0022] Forward and B Back) to obtain the insertion / the exit of the tubular element 2 into / from the human body .

[0023] The tubular element 2 typically has a circular cross-section with an external diameter ranging from 0. 908 mm to 2 .769 mm, an internal diameter ranging from 0. 603 mm to 2. 159 mm, a thickness ranging from 0.152 mm to 0.305 mm and can be made of stainless steel or other medical material .

[0024] The probe 1 further comprises an internal sleeve 6 axially sliding inside the tubular protection element 2 with opposite directions under the thrust of the handling system 5 and provided with a front end portion 6-a whose position with respect to the front end portion 3 of the tubular element 2 is adjustable . In particular, the front end portion 6-a may be contained - in a rest position shown in Figures 2 and 3 - inside the tubular protection element 2 or can at least partially project - in a position of use shown in Figure 4 from the tubular element 2.

[0025] The internal sleeve 6 typically has a circular cross-section with an outside diameter ranging between 0. 603 mm and 2. 159 mm and can be made of medical grade Polytetrafluoroethylene (PTFE) or generally in plastic material with medical specifications .

[0026] The internal sleeve 6 has a series of axially extending channels including : a first channel 7 housing a first emission optical fibre 8 having a front end 8-a (Figures 2 and 3) configured to supply an excitation signal to the tissue 4 and a rear end 8-b (Figure 5) configured to receive in input the excitation signal produced by an optical signal generator 9 (Figure 5) conveniently, the optical signal generator 9 is a solid-state laser usable for Raman spectroscopy and adapted to generate a wavelength signal of 532 nm,

[0027] 785 nm, 830 nm and 1064 nm ( Other wavelength choices are also possible; some of the most common ones are : 458nm, 473nm, 515nm, 532 nm, 594nm, 633 nm, 660nm; 785 nm, 830 nm, 980nm, 1064 nm) . a second channel 11 housing a second collection optical fibre

[0028] 12 having a front end 12-a configured to receive a response signal coming from the tissue and provided with a rear end 12-b configured to feed the response signal to a Raman spectrometer 13 (Figure 5) ; a third channel 15 extending over the entire length of the sleeve 6 and configured to feed a nano-particle-containing fluid into the tissue 4 - The dimensions of the third channel 15 may be in the order of 50 T 200pm; a fourth channel 17 extends over the entire length of the sleeve

[0029] 6 and housing an expandable element 18 configured to project from the end 6-a of the sleeve 6 when it is arranged in the rest position to expand and be arranged in contact with the internal walls of the external tubular protection element 2 (Figure 2 ) acting as a plug and separating the end 6-a of the sleeve 6 from the tissue 4 . The function of the expandable element 18 is to protect the optical fibres 8 and 12 from contamination until the arrival of the protection element 2 at the site where the measurement is to be carried out . When this position is reached, the expandable element

[0030] 18 is deflated and retracted into the respective fourth channel 17

[0031] (Figure 4 ) .

[0032] Conveniently, the expandable element 18 is of the balloon type and is realized using known technologies .

[0033] Conveniently, the first, second, third channel 7 , 11, 15 and the fourth channel 17 have a circular cross-section .

[0034] However, it is clear that the structure could be different from that shown in the figures since more emission optical fibres (and related channels ) and more collection optical fibres (and related channels ) could be provided. The internal sleeve 6 can in fact be configured to house N emission fibres and M collection fibres . More third channels 15 could also be provided for the fluid.

[0035] The optical fibres 8 and 12 may have a core preferably consisting of molten silicon or sapphire to reduce the fluorescent background . The choice of the optical fibres 8 and 12 does not in any way limit the invention . Different diameters and numerical apertures can be used to improve collection efficiency . For example, multimodal fibres with the pure silicon core and the hard polymer coating, a transmission region ranging from 400 T 2200 nm, a core with a diameter of 200 ± 5 pm, a coating with a diameter of 225 ± 5 pm and a numerical aperture (NA) of 0.50 can be used .

[0036] The third channel 15 is conveniently connected with a pressurised fluid delivery system 20 (Figure 5) such as a peristaltic pump or a pressurization system, both of known type . According to a preferred embodiment, the fluid carries a plurality of nanoparticles in suspension; the nanoparticles used for this application typically consist of a plasmonic biocompatible material (e . g . , gold, silver, copper, etc . ) that is of inert type and therefore usable in clinical applications . The particles have nanometric dimensions (preferably in the range 10 -r 100 nm) so as to create hotspots directly on the tissue 4 to be analysed, and have different geometries : spheres, sticks, triangles, hexagons, prisms, spirals, cubes, threads, and stars . In addition, the particles are functionalised, i . e . a specific molecule (e . g . antibody, aptamer, peptide) is covalently bound to the surface of the nanoparticle .

[0037] The molecule is a Raman reporter so defined because it has a specific Raman imprint when illuminated by the excitation laser . In this way, the Raman reporter performs a dual function : the tracking of the Raman signal and the possibility of engaging a recognition element capable of selectively and specifically recognizing a biomarker present on the cell membrane . The nanoparticles are closely related to the use of the Raman

[0038] SERS method, which, compared to the classic Raman technique, allows the amplification of the Raman signal in reception . The probe 1 is however also usable without the use of such microparticles in a classical Raman technology .

[0039] The front end 8-a of the first emission fibre 8 may be provided with a narrow-band band-pass filter (not shown) formed by a layered structure integrated into the fibre and formed by layers having different thickness and different refractive index so as to realize a phase-shifted Bragg grating .

[0040] The front end 12-a of the first collection fibre 12 may be provided with a non-shown high-pass optical filter formed by a layered structure integrated into the fibre and formed by layers having different thickness and different refractive index . The high- pass optical filter is used to suppress Rayleigh scattering so that only the light at a greater wavelength, which has undergone Stokes scattering, is collected from the collection fibre 12 .

[0041] The end 8-a of the first emission fibre 8 may also be provided with a flat metalens-type structure (of known type and not further detailed) formed by nano structures configured to focus the ray emitted by the fibre 8. As is well known, metalens can advantageously replace optical lenses that are larger and bulkier .

[0042] Metalens structures with high numerical aperture can be used on the collection fibre 12 to increase collection efficiency .

[0043] The narrow-band band-pass filter and a focussing metalens structure can therefore coexist on the same emission fibre 8.

[0044] The high-pass filter and a high numerical aperture metalens structure can therefore coexist on the same collection fibre 12 . In use, the external tubular protection element 2 is inserted into a portion of human tissue until it reaches a position of interest to be subjected to analysis, e . g . a portion of liver 4

[0045] (example : potential liver nodule) . Obviously these operations are carried out under anaesthesia, at least partially . During insertion the expandable element 18 is kept inflated (Figure 2 ) and the end portion 6-a is placed in the rest position (Figures 2 and 3) in order to protect the optical fibres 8 and 12. Then after reaching a measuring position - the expandable element 18 is deflated and stowed inside the fourth channel 17 (Figure 4 ) and the internal sleeve 6 is moved to the activation position . A nanoparticle-containing fluid

[0046] (in the SERS application) is then injected into the tissue using the third channel 15. Subsequently, it is possible to proceed with a fine placement of the position of the internal sleeve 6 with respect to the tissue 4 .

[0047] The optical signal generator 9 is activated (the solid-state laser is switched on) and thus the analysis of the signal received by means of the commercial Raman spectrometer 13 can start .

[0048] This spectrometer is controlled by a personal computer 21 which controls the entire system comprising the optoelectronic sensor realized according to the present invention, the laser source 9 and the Raman spectrometer 13. The personal computer 21 installs signal processing software detected by the second optical collection fibre

[0049] 12 configured to compare the spectrum of the received signal with stored libraries containing spectra of known type . The software also performs a qualitative and quantitative spectral analysis . By way of non-limiting example, the functions performed by the processing software may be as follows : 1 . deletion of the background;

[0050] 2 . Baseline correction by means of algorithms known in the literature such as Asymmetric Least Squared Modified multi- polynomialfit — Improved multi-polynomialfit or Adaptive iterativelyreweightedPenalisedLeastSquares (airPLS) ;

[0051] 3. test Outliers;

[0052] 4 . Z-score normalization;

[0053] 5. Principal Component Analysis - for example, this algorithm can be found on the open source library PythonScikit-learn;

[0054] 6. Linear Discriminant Analysis - for example, this algorithm can be found on the open source library PythonScikit-learn; and

[0055] 7 . Classification .

[0056] For example, the classification operation may provide as output data the indication of different types of tissue cells such as normal cells and pathological cells .

[0057] The advantages of the optoelectronic probe are as follows

[0058] • The system enables in vivo Raman / Raman SERS analysis not otherwise possible, enabling real-time identification of the type of tissue cells to be analysed;

[0059] • The use of metalens structures and integrated filters on the optical fibre makes the probe compact and minimally invasive .

[0060] • With metalens structures, it is possible to realize lenses with a high numerical aperture (almost unitary) with performance superior to those of traditional lenses;

[0061] • The handling system, together with the lenses, allows the optical beam to be focused at different points with variable depth; • The system using different functionalised nanoparticles is versatile and can be specialised to identify a variety of tumour markers and thus identify various types of tumour pathologies for diagnostic and prognostic purposes;

[0062] 5 The nanoparticles can be specific for different markers and a different reporter can be used as a code for each marker; and

[0063] The number of fibres can be optimised in order to have the correct signal-to-noise ratio in reception .

[0064] Numbers

[0065] 1 optoelectronic probe for the analysis of tissues

[0066] 2 external tubular protection element

[0067] 3 front end portion

[0068] 4 tissue

[0069] 5 handling system

[0070] 6 internal sleeve

[0071] 6-a end portion

[0072] 7 first channel

[0073] 8 first emission optical fibre

[0074] 9 optical signal generator

[0075] 11 second channel

[0076] 12 second collection optical fibre

[0077] 13 optical signal analyser

[0078] 15 third channel

[0079] 17 fourth channel

[0080] 18 expandable element

[0081] 20 system for the supply of pressurised fluid

[0082] 21 personal computer

Claims

CLAIMS1. - Optoelectronic probe for the analysis of tissues located inside the human body comprising : a flexible external tubular protection element (2) configured to be inserted with its front end portion (3) in a tissue (4) to be subjected to analysis and cooperating with a handling system (5) adapted to achieve axial movement of the tubular element (2) with opposite directions to achieve the insertion / the exit of the tubular element in the human body (4 ) ; an internal sleeve ( 6) sliding axially inside the tubular protection element (2) and provided with a front end portion ( 6-a) whose position with respect to the front end portion (3) of the tubular element 2 is adjustable between a rest position in which the front end (6-a) is contained in the tubular element (2 ) and a use position in which the front end ( 6-a) projects from the tubular element (2 ) ; the internal sleeve ( 6) has a series of axially extending channels including : at least one first channel (7 ) housing a first optical fibre( 8 ) having a front end (8-a) configured to supply an excitation signal to the tissue (4 ) and a rear end (8-b) configured to receive in input the excitation signal produced by an optical signal generator (9) ; at least one second channel ( 11) housing a second optical fibre( 12 ) having a front end (12-a) configured to receive a response signal coming from the tissue (4 ) and provided with a rear end (12— b) configured to feed the response signal to an optical signal analyser (13) ;at least one third channel ( 15) which is configured to feed a fluid, preferably a fluid containing nano-particles to the tissue(4 ) ; a fourth channel (17 ) housing an expandable element ( 18) configured to project, in use, from the end ( 6-a) of the sleeve ( 6) when it is arranged in the rest position to expand and be arranged in contact with the internal walls of the external tubular protection element ( 6) acting as a plug and separating the end ( 6-a) of the sleeve ( 6) from the tissue (4) .

2. - Probe according to Claim 1, wherein the expandable element(18) is of the balloon type .

3. - Probe according to one of Claims 1 or 2 wherein the front end (8-a) of the first emission fibre (8) is provided with a bandpass filter formed by a layered structure integrated into the fibre and formed by layers having different thickness and different refractive index so as to realize a phase-shifted Bragg grating .

4. - Probe according to any one of the preceding claims, wherein the front end (12-a) of the first collection fibre (12) is provided with a high-pass optical filter formed by a layered structure integrated into the fibre and formed by layers having different thickness and different refractive index; the high-pass optical filter is configured to eliminate Rayleigh scattering so that only light at longer wavelength, which has undergone Stokes scattering, is collected by the collection fibre ( 12) .

5. - Probe according to any one of the preceding claims, wherein the front end ( 8-a) of the first emission fibre ( 8) is provided with a flat metalens-type structure formed by nano structures configured to focus the ray emitted by the emission fibre (8) .

6. - Probe according to any one of the preceding claims, wherein the front end (12-a) of the second collection fibre (8 ) is provided with a flat metalens-type structure formed by nano structures .

7. - Probe according to any one of the preceding claims, wherein the tubular element has a circular cross-section with an external diameter ranging from 0. 908 mm to 2.769 mm and an internal diameter ranging from 0 . 603 mm to 2 .159 mm.

8. - Probe according to any one of the preceding claims, wherein the internal sleeve ( 6) has a circular cross-section with an external diameter ranging from 0. 603 mm to 2 .159 mm.

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