EP4132387A1

EP4132387A1 - A surgical tool, system and method for tissue characterisation

Info

Publication number: EP4132387A1
Application number: EP21718980.2A
Authority: EP
Inventors: Sven VAN LEEUWEN; Matthias VAN OOSTEROM; Fijs VAN LEEUWEN; Michael BOONEKAMP; Henk Van Der Poel; Krijn HOUWING
Original assignee: Leids Universitair Medisch Centrum LUMC
Current assignee: Leids Universitair Medisch Centrum LUMC
Priority date: 2020-04-09
Filing date: 2021-04-09
Publication date: 2023-02-15
Also published as: WO2021206557A1; NL2025324B1

Abstract

The invention relates to a surgical tool for coupling to a standard surgical instrument to provide that instrument with a capability to detect characteristics of subject tissues held in contact with at least one working surface of the instrument. The surgical tool comprises a housing for mounting in one or more apertures or cavities of the standard surgical instrument. The housing comprises an excitation source for exciting a subject tissue, a detector for detecting an emission from the subject tissue; and a signal transmission device which is communicatively coupled to the signal transmission device and operable to transmit in dependence on the emission detected by the detector, a signal to a signal processing device. The invention also relates to a surgical system comprising the tool, and a method of performing tissue visualisation and characterisation, optionally with the above-mentioned surgical tool.

Description

A Surgical Tool, System and Method for Tissue Characterisation

[0001] This invention relates to a surgical tool, system and method for tissue characterization during surgery.

BACKGROUND

[0002] Fluorescence imaging is commonly being used during (robot assisted) laparoscopic surgery. This has been made possible via incorporation of fluorescence imaging into surgical laparoscopes. The laparoscopes can be operated in both white light and fluorescence imaging modes to enable a surgeon to visualize the surgical field and assist in the delineation of tumour margins and identification of various structures such as blood vessels, nerves, ureters, bile ducts and lymph nodes and/or tissue regions such as cancerous tissue, into which an exogenous or endogenous fluorescent substance has accumulated. Each fluorescent substance will have a unique excitation peak and a unique emission peak which enables identification of the substance and therefore the tissue type in which it is present. Examples of approved fluorescent substances currently in use for fluorescence guided surgery include indocyanine green (ICG), methylene blue (MB), protoporfyrine X (PplX) and fluorescein sodium.

[0003] The improved visualization afforded by real-time fluorescence imaging in the surgical field as compared to standard unaided vision using white light imaging can also reduce the likelihood of damage to normal tissues and structures positioned near to the target tissue during surgery. However, a big constraint with current fluorescence imaging is that its implementation requires a surgeon to pause the surgical procedure, such as a resection, to perform fluorescence imaging to identify the target tissue followed by switching from the fluorescence mode to a white light mode in order to continue the surgical procedure under white light conditions, which is still considered best to assess and monitor the surgical field. The switching between fluorescence mode and white light mode on the laparoscope is done frequently during surgery to ensure that the surgical procedure is still targeting the correct tissue, i.e. that the (conventional) surgical instruments are being used to grasp, resection etc. the target tissue, and that, where appropriate, all target tissue has been removed. Repetitive switching leads to an increase in the time required to complete the surgical procedure, which is an undesirable surgical limitation, and may also result in confusion for less experienced surgeons when viewing the surgical field.

[0004] The present invention is designed to address at least the above-mentioned limitations of the prior art. BRIEF SUMMARY OF THE DISCLOSURE

[0005] In accordance with an aspect of the present invention there is provided a surgical tool comprising; an excitation source for exciting a subject tissue; a signal transmission device; a detector for detecting an emission from the subject tissue; the detector being communicatively coupled to the signal transmission device which is operable to transmit in dependence on what the detector is detecting, a signal to a signal processing device, wherein the surgical tool is configured to be coupled to or form a part of a surgical instrument, the surgical instrument comprising one or more grasping surfaces for grasping subject tissue, to provide the excitation source and the detector for detection of subject tissue emission, on the one or more grasping surfaces of the instrument.

[0006] Excitation source(s) and/or detector(s) forming a part of the invention may be configured to provide one or more of fluorescence, ultrasound, Raman spectroscopy, optoacoustic imaging, autofluorescence, absorption/ reflectance imaging, optical coherence tomography, magnetic resonance imaging (MRI), mass spectrometry and/or fluorescence life time sensing modalities and/or any other suitable sensing modality.

[0007] In another aspect, there is provided a surgical tool comprising a fluorescence excitation source for irradiating a subject tissue, the subject tissue comprising at least one fluorescent component; a signal transmission device; a detector for detecting fluorescence emission from the subject tissue; the detector being communicatively coupled to the signal transmission device which is operable to transmit in dependence on what the detector is detecting, a signal to a signal processing device, wherein the surgical tool is configured to be coupled to or form a part of a surgical instrument to provide the fluorescence excitation source and the detector for detection of subject tissue fluorescence emission, on a part of the instrument.

[0008] An advantage of the present invention is that the surgical tool can be coupled to a standard surgical instrument to convert it into a “smart” instrument, i.e. one capable of detecting characteristics of patient tissues held in contact with a working surface(s) of the instrument.

[0009] The signal may be indicative of the presence or absence of a fluorescent component in the subject tissue. The signal processing device may be operable to receive the signal and determine a tissue characteristic based on the fluorescence emission from the subject tissue. A tissue characteristic may be one or more of a tissue type, tumour cell(s), inflammation, lymphatic structure, ureters, bile ducts, nerve(s) and/or blood vessel(s).

[0010] The subject tissue may comprise a fluorescent component. The fluorescent component in the tissue may be endogenous (i.e. autofluorescence of biological structures) or exogenous (i.e. light originating from a fluorescent component introduced into the tissue). The fluorescent component in the tissue may comprise one or more dyes e.g. indocyanine green (ICG), methylene blue (MB), fluorescein, Cy5 and/or Cy7, PpIX. The fluorescent component(s) may be coupled to different tracers, i.e. a variety of tissue/ disease specific targeting vectors, e.g. for prostate-specific membrane antigen (PSMA) or proteins such as but not limited to human serum albumin (HSA). It will be appreciated that other fluorescent components or dyes can be used with the present invention although it may be necessary to modify the excitation and detection wavelengths accordingly. Examples of fluorescent dyes used in clinical applications and their respective excitation and emission wavelengths are given in Figure 13.

[0011] In the case of autofluorescence, a signal arising from a target tissue can be indicative of a particular tissue type or characteristic. Signal processing and comparison with reference data of this signal from the subject tissue could be used to predict a tissue type or characteristic. In the case of exogenous fluorescent components, by using a specific fluorescent component, its point of accumulation in the subject tissue can be identified meaning that a signal resulting from the exogenous fluorescent component is representative of a specific tissue type and/or characteristic.

[0012] The signal processing device and/ or a system controller may further process the emission signal to determine tissue characteristics. For example, if a signal on one single detector represents a reflectance or emission spectrum generated by different molecules in the tissue, the further processing, such as via computer-readable instructions, e.g. Software may be used to separate out the different components. In such an example, a software-based prediction model may be required to characterize the tissue composition.

[0013] The signal processing device may be physically coupled to the surgical tool. The physical coupling may comprise optical fibres. The physical coupling may comprise electrical cables. In one or more embodiments, there may be separate fibres for transmission of excitation and emission signals, respectively. In one or more embodiments, there may be a single fibre for both excitation and emission signals. The surgical system as claimed in any of claims 15 to 18, wherein the fluorescence excitation source and/or the detector comprises one or more optical fibres for fluorescence component excitation and/or signal detection, the fibres coupling the excitation source and/or the detector of the surgical tool with an excitation source and/or detector, respectively, positioned apart from the surgical tool.

[0014] The surgical tool may be coupled to the signal processing device via optical, electrical and/or wireless connection. In at least one embodiment, the signal processing device may be wirelessly coupled such as via a Bluetooth™ or other wireless connection, including but not limited to Infrared or Near-Field Communication (NFC).

[0015] The surgical tool may be configured to provide periodic and/or continuous or substantially continuous subject tissue excitation and detection so as to provide a periodic and/ or continuous or substantially continuous output of characteristics of the subject tissue. Therefore, irrespective of whether the surgical field is illuminated, for example by a surgical laparoscopic camera, in white light mode or fluorescence mode, the surgical tool of the present invention can continuously characterize the subject tissue, which may be positioned between the excitation source and the detector of the tool, based on the fluorescence emission from the subject tissue. Said emission may be as a result of an endogenous or an exogenous fluorescent compound. In one or more embodiments, subject tissue excitation may occur via an excitation source external to the surgical tool, such as by a laparoscopic camera and/or other external source, either instead of, or in addition to, excitation arising from the excitation source on the surgical tool. In one or more embodiments, it may be advantageous to provide substantially all of the excitation from an excitation source on or coupled to the surgical tool, as this allows localized control of emission that is independent of external illumination.

[0016] The surgical tool may comprise a first sensing modality and one or more additional sensing modalities. Each sensing modality is achieved by one or more excitation sources and one or more detectors on the surgical tool, each configured to excite a subject tissue and detect emission signals from the subject tissue, respectively. Each of the first sensing modality and one or more additional sensing modalities may include but not be limited to, ultrasound, Raman spectroscopy, optoacoustic imaging, fluorescence, absorption/ reflectance imaging, optical coherence tomography, magnetic resonance imaging (an example of which can be accessed via https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6204856/), mass-spectrometry (an example of which can be accessed via https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6426168/ and/or fluorescence life-time imaging (an example of which can be accessed via https://www.researchgate.net/publication/47698132_Fluorescence_lifetime_imaging_microscop y_for_brain_tumor_image-guided_surgery). It will be appreciated that one or more of these additional sensing modalities may require a suitable connection between the surgical tool and external equipment, such as for example, a connection between the surgical tool and/or instrument and a mass-spectrometer and optionally any necessary data processing equipment. In one or more of these examples, such as for example in the case of ultrasound, accuracy of sensing may be improved when at least the detector in the surgical tool is in direct contact with the subject tissue. Such direct contact may be achieved by, for example, coupling the surgical tool to a surgical instrument capable of grasping the subject tissue, such as surgical forceps, as described herein. It will be understood however that the aforementioned direct contact between the subject tissue and the surgical instrument is not necessarily essential and that in some cases satisfactory sensing may be achieved even when the instrument is not in direct contact with a subject tissue.

[0017] The surgical tool may further comprise means for coupling the tool to a surgical instrument. The coupling means may comprise a clip connection. In one or more embodiments, the surgical tool may be coupled to a surgical instrument using a push-fit/ interference fit connection.

[0018] The excitation source and/or the detector may not be limited to any particular type of emission excitation and/or detection, such as fluorescence. For example, the excitation source and/or detector may be configured for use in other contexts such as but not limited to medical ultrasound imaging. Such configuration may require specific excitation sources and/ or detection sources configured for use with e.g. ultrasound rather than configured for the purpose of fluorescence imaging. In one or more embodiments of the invention, there may be more than one type of excitation source and/or detector, each specifically configured to provide a specific modality such as fluorescence excitation via a laser directed through an optical fibre coupled to the surgical tool and detection via an optically filtered photomultiplier tube coupled to an optical fibre; and/or an excitation source comprising ultrasonic sound waves generated with piezo elements and driven with electrical current and a detector comprising piezo elements generating an electrical current for detecting ultrasonic sound waves. Such an embodiment may or may not be referred to as comprising “hybrid modality”. One or more embodiments may not comprise a fluorescence excitation source and detection source. In other words, the present invention is not necessarily limited to embodiments comprising a fluorescent modality, although fluorescence may be one of a number of sensing alternatives.

[0019] In accordance with a second aspect of the present invention there is provided a surgical system comprising a surgical tool according to the first aspect of the present invention, and a surgical instrument.

[0020] The surgical tool maybe coupled to a part of the surgical instrument. The surgical tool may be formed as a part of the surgical instrument. The surgical instrument may, or may not, be a “wristed” instrument, i.e. comprise at least one articulation mechanism.

[0021] The surgical instrument may comprise jaws. The fluorescence excitation source may be provided on one jaw. The fluorescence detector may be provided on another jaw. The fluorescence excitation source and the detector may be provided on the same jaw. Provision of the excitation source and/ or the detector on one or both jaws may be achieved by coupling the surgical tool to an excitation source and/or a detector, or by providing the excitation source and the detector completely within the surgical tool.

[0022] In one or more embodiments, an ultrasound detector may be provided on one jaw. In one or more embodiments, the fluorescence excitation source and the detector may be provided on another jaw.

[0023] The fluorescence excitation source and/or the detector may comprise one or more optical fibre(s) for fluorescence component excitation and/or signal detection. The one or more optical fibres may couple different parts of the excitation source and/or different parts of the detector. For example, an optical fibre, or other communication means, may couple an excitation source output on the surgical tool to an excitation source such as a laser positioned away from the tool. Also, for example, optical fibres, or other communication means, may couple a detector input on the surgical tool to a detector means such as photomultiplier tubes, or a spectrometer or photo-/ avalanche-diodes positioned away from the tool.

[0024] The excitation source may comprise one or more of lasers, such as wavelength specific lasers, light emitting diodes (LEDs), such as wavelength specific LEDS, optically filtered halogen/ xenon bulb(s), tunable white light lasers, or any other suitable excitation source. The detector may comprise one or more of (multiple) photomultiplier tubes, a spectrometer,

(multiple) photo-/avalanche-diodes, (optically filtered) miniaturized photodiodes or any other suitable detector means.

[0025] At least a part of the fluorescence excitation source and/or the detector may be positioned on one or more working surfaces of the surgical instrument. By working surfaces, it is meant any part of the surgical instrument intended to contact patient tissue(s). The working surface may be, but is not limited to, a grasping surface, a cutting surface and/or a tissue contact surface for e.g. tissue retraction.

[0026] The surgical system may comprise a means for focusing the fluorescence emission so as to focus or limit detection of fluorescence emission to that emitted from a subject tissue positioned adjacent a working surface which may, or may not, be a grasping surface of the surgical instrument. The means for focusing may comprise a reflective surface such as a mirror, and/or a lens, and/or a prism or any similar means of focusing emitted light. The means for focusing the emission may be mounted at an angle of between approximately 0-90° relative to a working surface, for example but not limited to a grasping surface of the surgical instrument. In at least one example, the reflective surface or other means for focusing the emission may be mounted at an angle of 45° relative to the working surface, which may, or may not be the grasping surface of the surgical instrument. The reflective surface may be planar or curved or conical.

[0027] At least a part of the surgical tool may be mounted in at least one cavity of the surgical instrument. For example, at least a part of the surgical tool may be mounted in at least one cavity in the jaws of a pair of forceps.

[0028] The fluorescence excitation source may be mounted in a cavity in one jaw of the surgical instrument. In at least one embodiment, the detector may be mounted in a cavity on another jaw of the surgical instrument.

[0029] At least a part of the surgical tool may be mounted into at least one cavity on the surgical instrument using a push-fit connection and/or clip connection and/or a sprung connection and/or a sliding connection.

[0030] The surgical instrument may comprise a pair of surgical forceps, or a pair of surgical scissors. In one or more embodiments, the surgical instrument may be configured for use during laparoscopic surgery.

[0031] The surgical tool, surgical instrument and /or the surgical system may be configured for use in robotic surgery. For example, the surgical tool and/or the surgical system may be configured to connect to a surgical robot, for example via a wired connection and/or via a wireless connection.

[0032] The surgical system may be configured to pass through a variety of standard trocar sizes. By standard trocar size it is meant any size of trocar that would usually be selected by a surgeon or otherwise qualified medical professional depending on the surgical requirements such as but not limited to the entry point to be used for trocar placement. Examples of trocar sizes used during laparoscopic procedures in which the trocar(s) are required to accommodate a laparoscope, instruments and/or significant tissue mass during removal of a target tissue, might range from 10mm or 12mm or larger.

[0033] In one or more embodiments, at least a part of the surgical system may be configured to be sterilizable and/ or disposable. For example, all or a part of the surgical tool and/or all or a part of the surgical instrument may be sterilizable and/or disposable.

[0034] The surgical system may be configured for coupling to a surgical robotic system. The surgical robotic system may comprise one or more of signal processing means, control means e.g. a controller, communication means, storage means, and/or a coupling means for coupling the surgical instrument comprising the surgical tool of the surgical system to the robot. Coupling between the robotic system and the surgical instrument(s) may be electrical, optical and/or via wireless communication channels.

[0035] In one or more embodiments, the surgical system may further comprise a white light source for illuminating a subject tissue under white light conditions. The surgical system may be operable to irradiate a subject tissue in which at least one fluorescent component has been introduced using the fluorescence excitation source provided on the surgical tool to enable continuous tissue characterization and visualization when the subject tissue is illuminated under white light conditions.

[0036] In one or more embodiments, subject tissue excitation may occur via an excitation source external to the surgical tool, such as by a laparoscopic camera and/or other external source, either instead of, or in addition to, excitation arising from the excitation source on the surgical tool. [0037] The surgical system may further comprise a signal processing device communicatively coupled to a signal transmission device of the surgical tool.

[0038] The signal processing device may be configured to receive, at an input, a signal relating to fluorescence emission from the subject tissue; determine the tissue characteristic by comparing the fluorescence emission detected by the detector with a reference fluorescence emission spectrum and/ or with a previously collected data set of fluorescence emissions corresponding to particular tissue characteristics.

[0039] Data collected during a surgical procedure may be collated and stored in a database that is used to generate a statistical model that allows prediction of tissue characteristics based on the collated data.

[0040] The fluorescence emission detected by the detector may comprise a single fluorescent emission or a plurality of fluorescent emissions.

[0041] The signal from the detector may comprise one or more of an audio signal, a quantitative signal and/or a visual signal. [0042] The surgical system may comprise a display means. The display means may be configured to output display data indicative of a tissue characteristic of at least a part of the subject tissue. The display data may include, for example, a visual representation of at least a part of the subject tissue and/or part of the surgical field; and/or an audible signal and/or a numerical signal indicative of one or more tissue characteristics. [0043] The signal from the detector may be indicative of different imaging signatures, for example but not limited to fluorescence, radioactivity and/or ultrasound signals.

[0044] The surgical system may be configured for use during laparoscopic surgery. The surgical system may be assembled outside of a surgical field. At least a part of the surgical system may be assembled within a surgical field. For example, the surgical tool may be coupled to a surgical instrument forming a part of the surgical system when the surgical instrument is positioned within the surgical field. By coupling the surgical tool and surgical instrument together in the surgical field rather than prior to entry into the surgical field via a trocar, it may be possible to select a smaller diameter trocar as would otherwise be necessary to accommodate the tool and instrument if they were coupled together prior to being inserted through the trocar. [0045] At least a part of the surgical system may be configured to be sterilizable and/ or disposable.

[0046] In accordance with a third aspect of the present invention there is provided a method of performing tissue visualization and characterization using the surgical tool of the first aspect of the invention and/ or the surgical system of the second aspect of the invention. [0047] In accordance with a fourth aspect of the present invention there is provided a method of performing tissue visualization and characterization, wherein the method comprises; illuminating a subject tissue which comprises a fluorescent component with a fluorescence excitation source; detecting a signal from the subject tissue indicative of a presence of the fluorescent component in the subject tissue; processing the signal to determine a tissue characteristic based on a fluorescence response of the subject tissue; wherein processing of the signal to determine a tissue characteristic is continuous irrespective of whether the subject tissue is illuminated under white light mode or fluorescence mode.

[0048] The method of the fourth aspect of the invention may be performed using the surgical tool of the first aspect of the invention and/or using the surgical system of the second aspect of the present invention.

[0049] In the method of the fourth aspect, provision of the fluorescence excitation source and detection of subject tissue fluorescence emission may be on one or more parts of the surgical instrument.

[0050] In one or more embodiments of the invention, automatic tissue recognition during the surgical procedure can be realized such as by using different colours on a visual display means to represent different tissue types. The displayed indication may in some embodiments be embedded in video footage displayed on the display means to provide an augmented reality indication of the surgical work flow. By way of example, emission signals indicative of particular tissue types or characteristics can be associated with particular colours in a reference database so that when a signal from a subject tissue is detected by the detector and compared to reference signals associated with particular colours by the controller, a match between the emitted signal and a reference signal causes the display means to display a representation of the subject tissue in a particular colour which is indicative of the tissue type or characteristic. For example, the colour red may be associated with a signal corresponding to tumour tissues, and so a subject tissue emitting a signal which is the same as the tumour tissue signal would be shown as red tissue on a visual representation. An example of a visual representation of the surgical field in such an embodiment is shown in Fig. 7 in which prostate cancer is indicated in red and is associated with fluorescence emission from Cy5, peripheral nerves are indicated in yellow and are associated with fluorescence emission from Fluorescein, and sentinel lymph nodes are indicated in green and are associated with fluorescence emission from ICG.

[0051] In one or more embodiments, such as the embodiment shown in Figure 13, the surgical tool and/or surgical system may be further configured to enable pose (position and orientation) determination and tracking of the surgical tool and/or surgical instrument by fluorescence and/or white light imaging, by way of comprising at least a first fluorescent marker 58 and a second fluorescent marker 59. In the embodiment shown in Figure 13, these markers are positioned on the outer surface of the housing 328. Such an embodiment may comprise one or more controllers, the controller(s) comprising at least one processor and memory. For example, the one or more controllers may be located on or in, or form a part of the tool and/or the instrument or surgical system. The memory may store computer readable instructions which may be executed by the one or more processors to perform a method for tracking the position and orientation of the surgical instrument. The controller may be configured to receive fluorescence imaging data captured of the surgical instrument and may be operable to store the fluorescence imaging data in the memory. The processor may be configured to perform a method in dependence on the fluorescence imaging data in order to determine a pose of the surgical device. The controller may be configured to output a pose signal indicative of the determined pose of the surgical instrument. In some embodiments the controller may be configured to output the pose signal to a user interface in order to output to a user of the system an indication of the pose of the surgical device. The determined pose may be output to the user in the form of visual, audible, haptic feedback or any combination thereof. The determined pose may in some embodiments be output in conjunction with other information, for example the fluorescence imaging data, contextual scan data or data from one or more further sensors to further aid navigation.

[0052] In one or more embodiments, the surgical system may further comprise a means for recording surgical procedures, which may have use for training purposes and/ or contribute to a machine learning function of the system.

[0053] In one or more embodiments, a spectrometer may be used to concurrently measure different fluorescent signals coming from different sources. It will be appreciated that the spectrometer would require appropriate configuration including but not limited to configuring to serially check each wavelength. In one or more embodiments, multiple photomultipliers can be used to increase sensitivity and provide multispectral (multi-wavelength) imaging. It will be appreciated that such an embodiment of surgical tool and/or surgical system may offer even greater analysis of the surgical field and may increase the sensitivity of detection of characteristics of the target tissue. For example, different emission wavelengths may be received by different photomultipliers, and/or there may be multiple emission detection channels. Read out of all signals may be simultaneous and the surgical tool may detect different emission signals simultaneously. In such embodiments, an example maximum total acquisition time may be approximately one second or less than one second. In such embodiments, examples of individual acquisition times may be between approximately 5 to 500 ms. In one or more embodiments, the surgical tool may be configured for sequential detection of different tracers. Emission measurements may contain multiple signals. Processing of the signals may take different forms so that a system user can determine how signal data is to be presented, e.g. via a visual output and/or numerical output and/or audible output etc.

[0054] In one or more embodiments, the system and/or method may comprise multiplexing options, i.e. fluorescence detection combined with different, i.e. non-fluorescence-based modalities, e.g. fluorescence detection of exogenous or endogenous substances (directed in the forceps) + ultrasound imaging of tissue or specific contrast agents (directed in the forceps).

[0055] In one or more other embodiments of the surgical tool and surgical system, the excitation source and the detector may both be positioned on one jaw, in the same, or separate housing(s). Such embodiment(s) may offer even greater flexibility to apply the present surgical tool to a wider variety of instruments to provide integrated optical detection in regular surgical instruments.

[0056] In another aspect of the present invention, there is provided a surgical tool for coupling to a standard surgical instrument to provide that instrument with a capability to detect characteristics of subject tissues held in contact with at least one working surface of the instrument, the surgical tool comprising: a housing for mounting in one or more apertures or cavities of the standard surgical instrument, the housing comprising: an excitation source for exciting a subject tissue; a detector for detecting an emission from the subject tissue; and a signal transmission device communicatively coupled to the detector and operable to transmit in dependence on the emission detected by the detector, a signal to a signal processing device.

[0057] The housing may comprise one or more coupling means that are shaped to couple with one or more complementarily shaped portion(s) of the surgical instrument.

[0058] The coupling means may comprise one or more of a clip connection, biasing means, slidable connection and/or interference (push-fit) connection.

[0059] The coupling means may comprise at least one projection which is shaped to fit into the one or more apertures or cavities of the standard surgical instrument for mounting the housing onto the surgical instrument.

[0060] The one or more apertures or cavies may be formed in or adjacent the at least one working surface of the surgical instrument.

[0061] The housing may comprise a first part and a second part.

[0062] The first part of the housing may be configured to be mounted into a first aperture or cavity of the standard surgical instrument.

[0063] The second part of the housing may be configured to be mounted into a second aperture or cavity of the standard surgical instrument.

[0064] The first and second apertures or cavities may be formed in first and second jaws, respectively, of the surgical instrument. [0065] The first and second jaws may be configured to hold subject tissue therebetween such that characteristics of the subject tissue can be determined by the surgical tool.

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of an embodiment of surgical tool according to the present invention;

Figure 2 is a view of a known pair of surgical forceps;

Figure 3 is a view of the embodiment of a surgical tool shown in Figure 1 coupled to the surgical forceps shown in Fig. 2 to form a part of a surgical system according to an aspect of the present invention;

Figure 4A is a view of the embodiment of surgical tool and forceps shown in Fig. 3 in which the jaws of the forceps are arranged in an open configuration, with a target tissue positioned between the open jaws and each jaw comprising a grasping surface;

Figure 4B is a side view of the embodiment of surgical tool and forceps shown in Fig. 4B in which the jaws of the forceps are arranged in a closed configuration with a target tissue being grasped by the jaws of the forceps.

Figure 5 is a side view of the embodiment of surgical tool and forceps shown in Fig. 4A showing the position of the reflective component within each housing of the surgical tool.

Figure 6 is a perspective view of another embodiment of a surgical tool according to the present invention, showing the tool coupled to a part of a surgical instrument to form a part of a surgical system according to an aspect of the present invention;

Figure 7 is a schematic representation of the configuration of an embodiment of a surgical tool and surgical system according to the present invention;

Figure 8 is a flow chart schematically illustrating the general steps of a fluorescence guided surgical procedure using both a conventional (known) technique and using an embodiment of surgical tool and an embodiment of method according to the present invention;

Figure 9A is an example of a visual representation of an output from the surgical system showing a surgical field and an embodiment of surgical system in which the surgical tool is coupled to the jaws of a pair of forceps as observed in white light mode;

Figure 9B shows the visual representation of the surgical field and surgical system shown in Figure 9A, under fluorescent light conditions, showing the surgical system comprising the surgical tool and forceps gripping tissue having a fluorescent component therein; Figure 10 shows an example of a visual representation of the surgical field as an output from the surgical system in an embodiment of surgical system and method which comprises multispectral fluorescence and/or multimodal detection (e.g., fluorescence and ultrasound);

Figure 11 is a perspective view of an embodiment of surgical tool according to the present invention comprising fluorescence detection and an ultrasound modality;

Figure 12 is a perspective view of an embodiment of surgical tool according to the present invention showing the tool coupled to the jaws of a surgical instrument to form a part of a surgical system according to an aspect of the present invention, wherein the tool is configured to enable pose tracking through fluorescence imaging; and

Figure 13 is a table providing examples of fluorescent dyes currently used in clinical applications and their respective excitation and emission wavelengths.

DETAILED DESCRIPTION

[0067] Referring to the drawings, in particular Figure 1, a surgical tool according to an embodiment of the invention is shown. The present embodiment relates to a fluorescence sensing modality. The surgical tool comprises a two-part housing designed to be clipped on to a pair of surgical forceps 12 as shown in Figs 2 and 3. In the present example, ProGrasp Forceps (RTM) 12 from the da Vinci (RTM) surgical robot system (Intuitive, Inc.) are used, although it will be appreciated that the surgical tool 10 could equally be applied to other surgical forceps or any other suitable surgical instrument.

[0068] The surgical forceps 12 comprise a pair of jaws 14, 16 with each jaw 14, 16 having a respective working surface 18, 20 intended for grasping biological tissue(s) 22 within a surgical field. The forceps 12 themselves have no means by which tissue(s) can be identified. In contrast, the surgical tool 10 does comprise means for determining tissue characteristics, as will be explained. Therefore, coupling of the surgical tool 10 to the forceps 12 provides the forceps 12 (or other suitable surgical instrument) with the capability to identify types and characteristics of tissues held within the jaws 14, 16 of the forceps 12 during use.

[0069] The surgical tool 10 comprises both an excitation part 24, configured to be coupled to an excitation source for irradiating a subject tissue, and an emission detector 26 configured to detect fluorescence emission from the subject tissue 22, each contained within a first 28 and second 30 housing, respectively. Each housing 28, 30 can be coupled to a respective cavity 32, 34 in the jaws 14, 16 of the forceps 12, as will be explained. In at least one embodiment, the surgical tool 10 is configured for communication and use with a read out console, such as for example, the OptoNuclear read out console (Eurorad, SA), which is configured to receive signals from the detector 26 relating to the fluorescence emission from the subject tissue(s) 22 responsive to an excitation signal; process the signals; and provide an output in dependence on the signals relating to characteristics of the tissue(s), in, for example, audible, numerical and/or graphical form. Whilst the present example relates to detection of fluorescent components in a subject tissue, it will be appreciated that other embodiments of the invention may be configured to detect other features, characteristics and/ or components/ substances within the subject tissue which may not be related to fluorescence.

[0070] It will be appreciated that the surgical tool 10 may be compatible with or modified for use with, other read out consoles or similar systems. The present embodiment is configured for detection of a fluorescent tracer, such as the fluorescent tracer ICG. However, it will be appreciated that the surgical tool 10 can also be used to detect other fluorescent substances or components, whether exogenous or endogenous. In such cases, it is anticipated that the surgical tool will be adapted to provide and detect the appropriate excitation and emission wavelengths of the specific fluorescent substance(s) or components. It will also be appreciated that the surgical tool may comprise other or additional detection modalities such as, but not limited to the additional modalities referred to in paragraph [0016]

[0071] As mentioned above, the present embodiment of surgical tool 10 comprises a first 28 and a second 30 housing, respectively, each housing 28, 30 configured to locate in a respective cavity 32, 34 on a respective jaw 14, 16 of a pair of forceps 12. The first housing 28 comprises the excitation part 24 and the second housing 30 comprises the emission detector 26 of the surgical tool 10.

[0072] Each housing 28, 30 comprises surgical grade stainless steel. However, it will be appreciated that other materials may be used instead of stainless steel for the housing and/or any other part of the device, in accordance with the relevant clinical requirements and standards. For example, the materials could be selected from a surgical grade carbon steel, titanium, or structural plastic. In the present embodiment, an example of which is shown in the Figure 1, each housing 28, 30 comprises a generally rounded-rectangular shell-like peripheral upper outer surface 36, 36’ with a generally planar base. The dimensions of the base correspond to those of the outer peripheral surface of the jaw 14, 16 of the forceps 12 so that the housing 28, 30 does not extend beyond or within the edge of the respective jaw 14, 16, but instead forms a substantially continuous edge with the jaw 14, 16 of the forceps 12, as shown in Fig. 3, for example.

[0073] Depending from the base is an elongate projection extending substantially the length of the base but bounded about its periphery by a portion of the planar base, said portion defining a flange for abutting an outer surface of a jaw of surgical forceps. The elongate projection comprises rounded ends and extends away from the base to a depth corresponding to the depth of a cavity in the forceps.

[0074] The elongate projection is sized and shaped so as to be slightly smaller than the internal dimensions of the cavity so that the projection engages with the inner surface of the cavity by an interference fit to enable coupling of the housing to the cavity by means of an interference fit. The depth of the elongate projection corresponds to the depth of the cavity 32, 34, and the base 38, 38’ of the elongate projection is planar, meaning that the projection fits entirely within the internal dimensions of the cavity and the base 38, 38’ is in the same plane as the working surface 18, 20 of the jaw 14, 16 of the forceps 12, as shown in Fig. 2. In the first housing 28, the excitation source 24 is positioned in the base 38 of the projection and in the second housing 30, the detector 26 is positioned in the base 38’ of the projection, as shown in Fig. 2 and Fig. 3B. This enables each of the excitation source 24 and detector 26 to be placed in direct contact with a subject tissue 22, as shown in Figs. 4A and 4B.

[0075] It will be appreciated that coupling of the housing to the cavity may be also achieved by other coupling means, such as by using complimentary fastener and fastener engagement features or connection means such as one or more clips. In one or more embodiments, the housing part(s) may slide over a surgical instrument and/or may utilize a spring-based mechanism to couple to the instrument. Examples of another possible embodiment is shown in Figure 6, although it will be appreciated that other shapes and configurations of surgical tool may also be possible. Features of each of the embodiment shown in Figure 6 which correspond to features shown in the embodiment illustrated in Figure 1 are identified using the same reference numerals as that used for the embodiment shown in Figure 1 , with the addition of a leading “1”. The embodiment of surgical tool shown in Figure 6 comprises a generally triangular shaped housing 128 adapted to couple into a generally triangular-shaped cavity in the jaw 114 of a pair of forceps. In another embodiment of surgical tool, the housing part may be configured to slide over a part of a surgical instrument, such as the jaw(s) of the surgical instrument. The significant difference between each of these embodiments as compared to the embodiment described above is the shape of the housing. In all other respects, the remaining components of the surgical tool 110 may be substantially in accordance with those described for the embodiment shown in Figure 1.

[0076] By configuring the housing 28, 30 of the surgical tool 10 to fit within the cavity 32, 34 on each jaw 14, 16 of the forceps 12, no modification is required to the inside geometry, i.e. the grasping (working surface) 18, 20 of the jaw(s) 14, 16 of the forceps 12. It will be appreciated that the shape of the housing may take different forms so as to allow coupling to a large variety of surgical instruments, thereby converting standard surgical instruments into instruments capable of tissue identification and characterization.

[0077] The housing 28, 30 can be removed from the cavity on each jaw 14, 16 by separating the housing 28, 30 and forceps jaw 14, 16 to release the interference connection between the two, or, in another example, by uncoupling the fastening means holding the housing in the cavity. This can be beneficial at least for the purpose of cleaning and/ or sterilization of the forceps and/or the surgical tool housings. By configuring the housing to fit within the cavity on each jaw of the forceps, the surgical tool is small enough so as not to hinder normal use of the forceps, thus fully exploiting the 6 degrees of freedom available for maneuverability of the ProGrasp (RTM) forceps. It will be appreciated that the number of degrees of freedom may vary depending on the particular surgical instrument used.

[0078] As mentioned above, the excitation source 24 is contained within the projection on the first housing 28 and is configured, in the present example, to emit an excitation signal capable of causing fluorescence of one or more fluorescent components or substances within the subject tissue 22. In the present embodiment, the excitation source 24 is configured to emit an excitation signal by virtue of a coupling via an optical cable 40, as will be explained, to a laser for fluorescence excitation 44 as shown in Fig. 7, although it will be appreciated that other excitation sources may be used instead.

[0079] As mentioned above, the emission detector 26 is contained within the projection on the second housing 30 and is configured to detect fluorescence emitted from the fluorescent substance or component within the subject tissue 22 responsive to the excitation signal from the excitation source 24. In the present embodiment, the detector 26 is coupled, via an optical cable 42 as will be explained, to an optically filtered (i.e. >810 nm) infrared-extended photomultiplier tube 46, as shown in Fig. 7, although it will be appreciated that other detector types may be used instead.

[0080] To improve accuracy of direction of the excitation field from the optical fibre 40 of the excitation source 24 to the subject tissue 22 and detection of emission signals from the subject tissue 22 held between the excitation source 24 and the detector, respectively, and to reduce the likelihood of detecting emission signals from surrounding tissues, the surgical tool 10 further comprises a mirror 47, 47’ contained within each of the first housing 28 and the second housing 30. Each mirror 47, 47’ is positioned at an angle between 0-90° relative to the length axis of the jaw 14 of the forceps 12 to which the surgical tool 10 may be applied, which in the present example is also the working surface 18 of the jaw 14. In one example, the angle of the mirror 47, 47’ in each housing 28, 30 was 45° relative to the working surface 18 of the jaw 14, as shown in Fig. 5. Although a mirror has been used in the present example, other reflective surfaces or devices may also be used instead for the purposes of directing the excitation field from the optical fibre 40 to the subject tissue 22 and directing the emission field from the subject tissue to the optical fibre 42 of the detector 26 of focusing signal detection on the subject tissue, such as but not limited to a lens, a prism, etc. Furthermore, in one or more alternative embodiments, such as for example an embodiment comprising a single optical fibre for transmission of both the excitation field and emission field, a single mirror or other suitable reflective surface or device may be utilized. In one or more embodiments, the optical fibre may comprise a curved or angled section, the curve or angle of which determines the direction in which the excitation field from the optical fibre is directed towards the subject tissue and/or the direction in which the emission field of the subject tissue is collected.

[0081] As mentioned above, an optical fibre or cable 40, 42 extends from a proximal edge of each housing 28, 30, as shown for example in Fig. 5 Fig. 7, Fig. 9A and Fig. 9B and can be removably coupled to the housing. The term “proximal” is intended to refer to a region of the housing which is positioned away from the tip of the forceps, i.e. nearest to a handle of the forceps. The term “distal” is intended to refer to a region of the housing which is positioned nearest to the tip of the forceps, i.e. away from a handle of the forceps. In the present example, the fibres 40, 42 comprise an acrylic optical fibre and each have a 1mm diameter and a 0.51 numerical aperture. The optical fibres or other communication means may be coupled to the housing at a different location to that described above, in one or more alternative embodiments of the invention. Although the present embodiment describes a housing which may be removably coupled to the surgical instrument, it will be appreciated that one or more embodiments of the invention may comprise a housing which is not removable from a part of the surgical instrument. In such an embodiment, cleaning and sterilizing of both the instrument and the surgical tool is done as a whole, instead of the surgical tool being removed for cleaning and sterilizing purposes. In addition to or instead of cleaning and sterilizing the surgical tool and instrument as a whole, the non-removable surgical tool and surgical instrument combination may be semi-disposable, i.e. disposed of after a predetermined number of use cycles, or entirely disposable, i.e. disposed of after a single use.

[0082] In the present embodiment, the optical fibre 40 extending from the first housing 28 is adapted to be coupled to a fluorescence light excitation source 44 as schematically shown in Fig. 7. In one embodiment of surgical system 50 according to the present invention, the fluorescence light excitation source is a 785nm laser, providing an optical power of approximately 3.7mW/cm²at the fibre output. It will however be appreciated that the aforementioned laser could be substituted by or be supplemented by any other suitable fluorescence excitation source, or combination of sources may be used to irradiate the target tissue, such as but not limited to other wavelength specific lasers, wavelength specific light emitting diodes (LEDs), an optically filtered halogen/ xenon bulb, or tunable (white light) lasers. Examples of fluorescent dyes used in clinical applications and their respective excitation and emission pairs are given in Fig. 13.

[0083] In the present embodiment, the optical fibre 42 extending from the second housing 30 is adapted to be coupled to an optically filtered (i.e. >810nm) infrared-extended photomultiplier tube 46 (H10721-20, Hamamatsu Photonics kk.) for fluorescence emission detection. In the present example of surgical system 50, and in accordance with an embodiment of the method of the present invention, sample time for detection is set at 0.5 seconds and fluorescence detection is depicted by both a numerical (i.e. count(s)) and audible-read out. It will be appreciated that other fluorescent emission detector types can be used, including but not limited to (multiple) photomultiplier tubes, spectrometers or (multiple) photo- / avalanche-diodes.

[0084] In at least the present example, the fibres 40, 42 are arranged in-line with the shaft of the forceps 12 so as to provide an arrangement that keeps within the boundaries of standard trocar sizes. In the present example, “standard trocar sizes” refers to any trocar size typically used in laparoscopic surgery. This arrangement has the additional benefit of enabling the surgical tool to be assembled away from the patient and then introduced into the surgical field, e.g. the abdominal cavity, via a standard trocar. In one or more embodiments, it is also possible to assemble the surgical tool 10 and instrument 12 in the surgical field itself. This provides the potential benefit of being able to select a smaller trocar than may otherwise be required to accommodate the surgical tool and instrument combination as it passes through the trocar into the surgical field.

[0085] Signals representative of emission detected by the detector 26 of the surgical tool 10 are transmitted to a controller 49 via communication means for subsequent transmission to a user interface on a surgical or read out console configured to display the tissue characteristics in dependence on the detected emission, in a given output form such as numerical, graphical, audible etc. As mentioned above, in the present example, the communication means comprises an optical cable. The optical cable (or communication means more generally) couples the detector to the controller. It will be appreciated however that the communication means is not necessarily limited to an optical cable but may comprise any means of enabling communication between components of the surgical system.

[0086] In an alternative embodiment, (not illustrated) optical fibres are not coupled to the housing. In an example of such an alternative embodiment, the excitation source comprises an arrangement of miniaturized laser diodes or LEDs, and the detector comprises optically filtered miniaturized photodiodes, or similar devices. In this embodiment, the surgical tool is completely contained within the housing parts and therefore does not require use of optical cables to connect to the detector. For example, in such an embodiment, one or more surface mounted LEDs of 780 nm may be mounted in or onto one housing, and optically filtered (>800nm using an optical long pass filter) photodiodes may be mounted in or onto the other housing. Communicative coupling to the surgical or read out console or other device is achieved via wireless communication such as Bluetooth™ which enables emission signals detected by the detector to be transmitted to the surgical console for outputting in the form of a visual, and/or or audible signal. However, it will be appreciated that in embodiments of the invention which do not comprise optical cables, electrical cables and power supplies such as batteries, for at least the purpose of supplying power to the surgical tool will still be required.

[0087] The controller 49 comprises at least one processor and a memory. The memory may store computer readable instructions which may be executed by one or more processors to perform a comparison of signals detected by the detector in dependence on fluorescence emission from fluorescent substances or components within the subject tissue 22 positioned between the excitation source 24 and the detector 26 of the surgical tool 10, with reference emission data stored within a database and associated with one or more tissue characteristics, to determine a tissue characteristic of the subject tissue based upon a match between the detected emission signal and a reference signal stored in the database. Said match can be indicative of a tissue type, such as a blood vessel, nerve etc., and/or a tissue characteristic such as cancerous cells etc.

[0088] The controller 49 is configured to output a signal indicative of the determined tissue characteristic. In some embodiments, the controller 49 may be configured to output the tissue characteristic signal to a user interface 52 which may output the signal in the form of, for example, a graphical representation, and/or an audible representation, and/or a numerical representation and/or any other form capable of providing an indication to a user, such as a surgeon or any other person wholly or partially in control of the surgical system 50, as to one or more characteristics of the subject tissue 22.

[0089] Although the present embodiment describes a single controller, it is to be appreciated that more than one controller may be implemented, each of which being communicatively coupled via a communication means.

[0090] A method according to one embodiment of the invention will be described in the context of laparoscopic surgery and with a pair of ProGrasp (RTM) forceps as the illustrative example of surgical instrument to which an embodiment of surgical tool according to the present invention is coupled. However, it will be appreciated that the method of tissue characterization and/or surgical tool and/or system of the present invention may be utilized in other types of surgery, and that the surgical tool may be coupled to other types of surgical instruments to form an embodiment of surgical system and/ or embodiment of surgical method according to the present invention.

[0091] In one example, the method comprises a step of coupling an embodiment of surgical tool 10 to the surgical forceps 12. In this example, the surgical tool 10 comprises an excitation part 24 and an emission detector 26 substantially as described above and each contained within their respective housing parts 28, 30 each of which is sized and shaped so as to couple to the cavity 32, 34 on each jaw 14, 16 of the forceps 12 via an interference fit. The first housing part 28, comprising the excitation source 24 is positioned adjacent a first jaw 16 of the forceps 12, and aligned with the internal peripheral edge of the cavity 32 therein. Once aligned, a user applies pressure to the uppermost surface 36 of the housing part 28 to cause the housing 28 to move into the cavity 32 such that the excitation source 24 itself, e.g. a laser or LEDs faces the cavity and working surface of the opposing jaw 14 when the jaws 14, 16 of the forceps 12 are closed. The housing part 28 is inserted into the cavity until the base 38 of the housing part from which the excitation source 24 is visible, is level with the working surface 20 of the jaw 16. The second housing part 30 comprising the detector 26 is coupled to the opposing jaw 14 in the same manner. When both housing parts 28, 30 are coupled to the forceps 12, the housing parts 28, 30 fit substantially completely within the cavities 32, 34 and each of the excitation source 24 and detector 26 respectively are facing the opposing jaw so that they will be positioned adjacent a subject tissue 22 when said tissue 22 is grasped by the jaws 14, 16 of the forceps 12. An example of this arrangement is shown in Figs. 2, 3A and 3B.

[0092] The assembled surgical tool 10 and forceps 12 form an embodiment of surgical system 50 according to the present invention. The surgical system 50 is introduced into the surgical field, which in the present example is within the abdominal cavity via a 12mm trocar. As mentioned above, in other surgical examples, the trocar size used may be different, the surgical field location may be different and/ or the surgical system may be assembled within the surgical field instead of outside of it as in the present example. A surgical laparoscopic camera (not shown) is used to illuminate the surgical field in both fluorescence mode 54 and white light 56 mode, as schematically illustrated in Fig. 8 and illustrated byway of a photograph of the illuminated surgical field in Figs. 9A and 9B.

[0093] Once in the surgical field, a subject tissue 22 is grasped within the forceps 12 and is then irradiated with light from the fluorescence excitation source 24 located in the first housing 28 as explained above. Any fluorescence emission produced by the subject tissue in response to the irradiation is detected by the detector 26 in the housing 30 on the second jaw and returns through the optical fibre. In the present embodiment, the detector 26 comprises (multiple) photomultiplier tubes, although it will be appreciated that a spectrometer might equally be utilized as the detector in another embodiment. In a further embodiment, the detector may comprise (multiple) photodiodes or avalanche photodiodes.

[0094] During a conventional surgical procedure, the subject tissue is illuminated in both white light mode 56 and fluorescence mode 54 by the laparoscopic camera, as schematically illustrated in Fig. 8. This enables the surgeon or other user of the surgical system 50 to visualize the subject tissue 22 under both white light conditions W which are optimal for surgical resection and as shown in Fig. 9A, and fluorescent conditions F which are optimal for tissue identification and characterization and shown in Fig. 9B.

[0095] However, by using the surgical tool and/or surgical system of the present invention, detecting emitted signals from the subject tissue 22 held within the working surfaces 18, 20 of the forceps 12 can be detected by the surgical tool, meaning that tissue characterization of the tissues being grasped and measured by the surgeon via the surgical instrument can continuously occur during the surgical procedure, irrespective of whether the surgical field is illuminated under white light conditions 54 or fluorescence conditions 56. Importantly, the surgical tool 10 enables continuous tissue characterization even when the surgical field is in white light conditions W as shown in Fig. 9A, which means that the surgeon does not need to keep switching the laparoscopic camera from white light mode to fluorescence mode (schematically represented in Fig. 8 as the switching steps contained within the broken line) to perform tissue characterization because the surgical tool and surgical system provides a continuous tissue characterization output. This reduced, or even eliminated requirement (depending on the surgeon’s preference) to keep switching between white light mode and fluorescent mode when using the present invention can therefore improve surgical efficiency and makes the fluorescent mode traditionally used to identify subject tissue during conventional surgery, redundant. However, it should be noted that the present invention does not preclude the use of switching from white light mode to fluorescent mode, if the surgeon desires.

[0096] Furthermore, since the surgical tool can be attached to or incorporated into a wide variety of surgical instruments, including traditional surgical instruments, without requiring any hardware modification to the surgical instrument itself, the need to frequently insert and remove an additional instrument in and out of the surgical field for the purpose of tissue characterization is avoided. This advantage also makes it easier to frequently check tissue using the surgical system (surgical tool and instrument) during the surgical procedure. The surgical tool and system allow for continuous (or periodic if preferred) measurement and characterization of the subject tissue during surgery in both white light conditions and fluorescence imaging setting without any disruption to the surgical procedure itself.

[0097] Since the output can take many different forms, including a colour coded representation R of the surgical field as shown by way of example in Fig. 10, and/or an audible warning and/or numerical indication of emission signals, the surgeon or other user of the surgical tool 10 and surgical system 50 has multiple options for confirming the type (or other characteristic) of subject tissue 22 held between the excitation source 24 and the detector 26 on the surgical tool 10, without needing to use the fluorescence mode F on the laparoscopic camera, as is currently customary practice during surgical resections.

[0098] An example of an embodiment of a method of the present invention is described with reference to an in vivo evaluation in porcine models of the surgical tool of the present invention, and an ex vivo evaluation with prostate cancer samples. In vivo evaluation involved investigation of 1) tissue vascularization detection; and 2) lymph node detection. For tissue vascularization detection, ICG was injected intravenously (1.5 ml, 2.5 mg/ml solution in saline) approximately 1 hour before surgery.

[0099] For lymph node detection, ICG (-0.2 ml, 2.5 mg/ml solution in saline) was injected locally into the abdominal wall or muscle using a needle attached to a syringe using a flexible tubing system. After insertion of the needle through the trocar, the surgeon placed a number of tracer deposits at different anatomical locations to induce drainage towards lymph nodes. To cross-validate functioning of the present surgical tool and instrument combination, the Firefly™ robotic laparoscope was used for ICG fluorescence imaging.

[00100] During the ex-vivo evaluation, surgical lymph node specimens of 3 prostate cancer patients were used. Each patient underwent a robot-assisted laparoscopic sentinel lymph node biopsy procedure, extended pelvic lymph node dissection and prostatectomy. To guide intraoperative dissection of the sentinel lymph nodes, the hybrid tracer ICG-^99mTc-nanocolloid comprising a fluorophore and a radioisotope was injected intra-prosthetically using 4 deposits, in the morning before surgery in a similar manner to that described above. Using both lymphoscintigraphy and single-photon emission computer tomography/ x-ray computed tomography (SPECT/CT) imaging, the number and location of lymph nodes were mapped. After surgical removal in the afternoon, the present surgical tool mounted onto forceps from the Da Vinci (RTM) system was used ex vivo to determine which lymph nodes contained tracer uptake and which did not, thus identifying the sentinel lymph nodes. Functioning of the surgical tool and forceps was verified using the known Firefly™ fluorescence laparoscope and further by cross validating with a known gamma detection probe to determine the radioactive moiety of the sentinel lymph node tracers.

[00101] When coupled to the surgical forceps, the positioning of the present surgical tool within the cavity on each jaw of the forceps means that normal use of the forceps remains unhindered, thus fully exploiting the available degrees (e.g. 6 degrees) of freedom available for maneuverability with the forceps. In both the open and closed position of the jaws of the forceps, without any tissue present in between the jaws, no count(s) were detected by the detector and no sound was generated by the signal processing device.

[00102] As mentioned above, the combination of the forceps and surgical tool of the present example, when coupled together, is small enough to fit through a 12mm trocar. This allows a surgeon to work in the surgical field in a way that is consistent with conventional surgical techniques and practice, while the surgical tool enables a real-time detection of tissues and communication (via a user interface) of tissue characteristics. In the present example, in addition to audible feedback, the surgical tool provides a count rate proportional to the amount of fluorescence detected.

[00103] An example of a hybrid (multiplexing) modality of the invention is shown in Fig. 11. As with the previously described embodiment, the hybrid surgical tool 200 comprises a first housing 228 and a second housing 230. Each housing 228, 230 is configured to be secured to the periphery of a cavity in each jaw 214, 216 of a surgical instrument, which in the present example comprises forceps 212, via an interference fit. It will be appreciated that this interference fit coupling is merely an example, and that in other embodiments, the housing may be coupled to the forceps in a different manner.

[00104] The first housing 228 comprises a fluorescence modality 280 comprising a fluorescence excitation source, a fluorescence emission detector and a mirror 247 for directing the excitation and emission fields, substantially in accordance with the corresponding features of the embodiment described above, with the exception that both the excitation source and the detector are provided on a single (first) jaw 214. The first housing 228 has an optical cable extending from a proximal edge of the housing, as shown in Fig. 11 and substantially in accordance with the previously described embodiment. The optical cable is adapted to be coupled to a fluorescence light excitation source (not shown in Fig. 11) which, in one example is a 785nm laser, providing an optical power of approximately 3.7mW/cm² at the fibre output, such that the aforementioned laser is communicatively coupled with the excitation source in the housing via the optical cable, substantially as per the previously described embodiment. It will however be appreciated that the aforementioned laser could be substituted by or be supplemented by any other suitable fluorescence excitation source, or combination of sources may be used to irradiate the target tissue, such as but not limited to other wavelength specific lasers, wavelength specific light emitting diodes (LEDs), an optically filtered halogen/ xenon bulb, or tunable (white light) lasers. The aforementioned optical cable is also connected at one end is connected to the detector in the first housing 228 and at the other end is connected to a photomultiplier tube, in the present example; an optically filtered (i.e. >810nm) infrared- extended photomultiplier tube 46 (H10721-20, Hamamatsu Photonics kk.), for fluorescence emission detection. Therefore, in the example embodiment shown in Figure 11, both excitation and emission signals travel through one and the same optical fibre. Optical separation at the output of this optical cable may be necessary when a single optical fibre is used to transmit both excitation and emission signals. In one or more embodiments, the aforementioned optical cable could be substituted by two different optical cables, with one cable being for excitation purposes and one cable for transmission of emission signals.

[00105] In at least the present example, the optical cables are arranged in-line with the shaft of the forceps 212 so as to provide an arrangement that keeps within the boundaries of standard trocar sizes. In the present example, “standard trocar sizes” refers to any trocar size typically used in laparoscopic surgery. This arrangement has the additional benefit of enabling the surgical tool to be assembled away from the patient and then introduced into the surgical field, e.g. the abdominal cavity, via a standard trocar. In one or more embodiments, it is also possible to assemble the surgical tool 200 and instrument 212 in the surgical field itself. This provides the potential benefit of being able to select a smaller trocar than may otherwise be required to accommodate the surgical tool and instrument combination as it passes through the trocar into the surgical field.

[00106] The second housing 230 comprises an ultrasound modality 282, comprising an ultrasonic excitation source and an ultrasonic emission detector. As with the previously described embodiment, the second housing 230 is configured to be fitted into a cavity on a second jaw 216 of the forceps 212 via, in the present example, an interference fit. As with the previous example, a subject tissue 22 is grasped between the jaws 214, 216 of the forceps. In the present embodiment, an electrical cable connects the ultrasonic excitation source, consisting of piezoelectric elements, in the second housing 230 with a typical ultrasound generation system, generating a sequence of electrical pulses over the cable, inducing a specific pattern of ultrasound waves in the jaw of the instrument via the piezoelectric elements. The ultrasonic detector in the second housing also consists of piezoelectric elements and is also coupled with an electrical cable to a typical ultrasound acquisition system, processing/analyzing the electrical pulses emitted by the detector piezoelectric elements as a consequence of the ultrasound waves received in the jaw of the instrument. Comparing both emitted and received electrical signals allows to determine the material composition of the tissue grasped within the forceps, followed by an ultrasound image of this tissue.

[00107] Each of the fluorescence excitation source and ultrasonic excitation source respectively excites the subject tissue and the resulting fluorescence and ultrasonic emissions from the subject tissue are detected by the fluorescence detector and the ultrasonic detector, respectively.

[00108] In much the same way as with the aforementioned fluorescence only embodiment, signals representative of emission detected by each of the fluorescence emission detector and ultrasonic detector, respectively, are transmitted to a signal processing device and a controller via communication means for subsequent transmission to a user interface on a surgical or read out console configured to display the tissue characteristics in dependence on the detected emission, in a given output form such as numerical, graphical, audible etc. As mentioned above, in the present example, the communication means comprises an optical cable. The optical cable (or communication means more generally) couples the detector to the controller. It will be appreciated however that the communication means is not necessarily limited to an optical cable but may comprise any means of enabling communication between components of the surgical system.

[00109] Although the present examples comprise a fluorescence modality, it will be appreciated that the presence of a fluorescence modality is not necessarily essential and has been selected from a range of possible sensing modalities byway of example only. For example, the surgical tool of the present invention can be produced to house any suitable sensing modality and can be coupled to a surgical instrument and/or surgical system in the same way as described above, save for configuring the excitation source and detector to suit the particular modality. An example schematic set up of a surgical tool substantially in accordance with the present invention but not necessarily including a fluorescence sensing modality is now described.

[00110] The excitation source and/or the detector may comprise one or more optical fibre(s). The one or more optical fibres may couple different parts of the excitation source and/or different parts of the detector. For example, an optical fibre, or other communication means, may couple an excitation source output on the surgical tool to an excitation source such as a laser positioned away from the tool. Also, for example, optical fibres, or other communication means, may couple a detector input on the surgical tool to a detector means such as photomultiplier tubes, and/or a spectrometer or photo-/ avalanche-diodes, and/ or piezo elements positioned away from the tool. In one or more embodiments, for example in which piezo elements are positioned away from the surgical tool, it may be preferable to provide an additional acoustical transmitting medium between the piezo elements and the surgical tool. In one or more embodiments, piezo elements may be placed directly on a surface of a surgical instrument, such as for example directly in a jaw of a pair of forceps, such as shown in relation to features 230 and 282 of Figure 11.

[00111] The excitation source may comprise one or more of lasers, such as wavelength specific lasers, LEDs, such as wavelength specific LEDS, optically filtered halogen/ xenon bulb(s), tunable white light lasers, or any other suitable excitation source. The detector may comprise one or more of (optically filtered) (multiple) photomultiplier tubes, an (optically filtered) spectrometer, (multiple) (optically filtered) photo-/avalanche-diodes, (optically filtered) miniaturized photodiodes, piezo elements or any other suitable detector means. It is to be appreciated that for every optical detection method, optical filtering may be required depending on the setup. It is also to be appreciated that different excitation sources and detectors may require a slightly different configuration within the surgical tool and/or surgical system than that described with reference to the fluorescence-based example of the present invention. For example, an embodiment comprising mass-spectrometry and/or Raman requires inductively coupled plasma mass spectrometry (ICP-MS). Also for example, an embodiment comprising a magnetizing modality, such as MRI, may require an exciting radiofrequency (RF) coil and a receiving RF coil for detecting the changes in the magnetic field induced by the subject tissue.

[00112] The surgical tool may comprise a first sensing modality and one or more additional sensing modalities. Each of the first sensing modality and one or more additional sensing modalities may include but not be limited to any one or more of those mentioned in paragraph [0015] It will be appreciated that one or more of these additional sensing modalities may require a suitable connection between the surgical tool and external equipment, such as for example, a connection between the surgical tool and/or instrument and a mass-spectrometer and optionally any necessary data processing equipment. In one or more of these examples, such as for example in the case of ultrasound, accuracy of sensing may be improved when at least the detector in the surgical tool is in direct contact with the subject tissue. Such direct contact may be achieved by, for example, coupling the surgical tool to a surgical instrument capable of grasping the subject tissue, such as surgical forceps, as described herein. It will be understood however that the aforementioned direct contact between the subject tissue and the surgical instrument is not necessarily essential and that in some cases satisfactory sensing may be achieved even when the instrument is not in direct contact with a subject tissue.

[00113] At least a part of the excitation source and/or the detector may be positioned on one or more working surfaces of the surgical instrument which may not necessarily be a grasping surface. By working surfaces, it is meant any part of the surgical instrument intended to contact patient tissue(s). For example, the working surface may be, but is not limited to, a cutting surface and/or a tissue contact surface for e.g. tissue retraction.

[00114] The surgical system may comprise a means for focusing the emission so as to focus or limit detection of emission to that emitted from a subject tissue positioned adjacent a working surface which may, or may not, be a grasping surface of the surgical instrument. The means for focusing may comprise a reflective surface such as a mirror, and/or a lens, and/or a prism or any similar means of focusing emitted light. The means for focusing the emission may be mounted at an angle of between approximately 0-90° relative to a working surface, for example but not limited to a grasping surface of the surgical instrument. In at least one example, the reflective surface or other means for focusing the emission may be mounted at an angle of 45° relative to the working surface, which may, or may not be the grasping surface of the surgical instrument. The reflective surface may be planar or curved or conical.

[00115] At least a part of the surgical system may be mounted in at least one cavity of the surgical instrument. For example, at least a part of the surgical tool may be mounted in at least one cavity in the jaws of a pair of forceps.

[00116] The excitation source may be mounted in a cavity in one jaw of the surgical instrument. In at least one embodiment, the detector may be mounted in a cavity on another jaw of the surgical instrument.

[00117] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. [00118] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[00119] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

1. A surgical tool for coupling to a standard surgical instrument to provide that instrument with a capability to detect characteristics of subject tissues held in contact with at least one working surface of the instrument, the surgical tool comprising: a housing for mounting in one or more apertures or cavities of the standard surgical instrument, the housing comprising: an excitation source for exciting a subject tissue; a detector for detecting an emission from the subject tissue; and a signal transmission device communicatively coupled to the detector and operable to transmit in dependence on the emission detected by the detector, a signal to a signal processing device.

2. A surgical tool as claimed in claim 1, wherein the housing comprises one or more coupling means that are shaped to couple with one or more complementarily shaped portion(s) of the surgical instrument.

3. A surgical tool as claimed in claim 2, wherein the coupling means comprises one or more of a clip connection, biasing means, slidable connection and/or interference (push- fit) connection.

4. A surgical tool as claimed in claim 2 or claim 3, wherein the coupling means comprises at least one projection which is shaped to fit into the one or more apertures or cavities of the standard surgical instrument for mounting the housing onto the surgical instrument.

5. A surgical tool as claimed in any preceding claim, wherein the one or more apertures or cavities is formed in or adjacent the at least one working surface of the surgical instrument.

6. A surgical tool as claimed in any preceding claim, wherein the housing comprises a first part and a second part.

7. A surgical tool as claimed in claim 6, wherein the first part of the housing is configured to be mounted into a first aperture or cavity of the standard surgical instrument.

8. A surgical tool as claimed in claim 6 or claim 7, wherein the second part of the housing is configured to be mounted into a second aperture or cavity of the standard surgical instrument.

9. A surgical tool as claimed in claim 8 when dependent on claim 7, wherein the first and second apertures or cavities are formed in first and second jaws, respectively, of the surgical instrument.

10. A surgical tool as claimed in claim 9, wherein the first and second jaws are configured to hold subject tissue therebetween such that characteristics of the subject tissue can be determined by the surgical tool.

11. A surgical tool as claimed in any preceding claim, wherein the excitation source comprises a fluorescence excitation source for irradiating subject tissue and the detector is configured to detect fluorescence emission from the subject tissue.

12. A surgical tool as claimed in any preceding claim, wherein the excitation source and/or detector are/is configured to provide one or more of ultrasound, Raman spectroscopy, optoacoustic imaging, absorption/ reflectance imaging, optical coherence tomography, magnetic resonance imaging and/or fluorescence life-time sensing modalities.

13. A surgical tool as claimed in any preceding claim, wherein the signal is indicative of a presence or absence of a fluorescent component in the subject tissue and the signal processing device is operable to receive the signal and determine a tissue characteristic based on any fluorescence emission from the subject tissue,

14. A surgical tool as claimed in any preceding claim, wherein the signal processing device is physically coupled to the surgical tool.

15. A surgical tool as claimed in any of claims 11 to 14, wherein the fluorescence excitation source can be configured to provide a continuous fluorescence excitation mode.

16. A surgical tool as claimed in any preceding claim, wherein the surgical tool comprises one or more fluorescent markings on an external surface of the tool for enabling pose determination and/ or tracking of the surgical tool.

17. A surgical tool as claimed in any preceding claim, further comprising a means for focusing the emission so as to limit detection of emission to that emitted from a subject tissue positioned adjacent the grasping surface of the surgical instrument.

18. A surgical tool as claimed in claim 17, wherein the means for focusing the emission comprises a reflective surface mounted at an angle of between approximately 0 - 90° relative to one or more grasping surfaces of a surgical instrument.

19. A surgical system comprising a surgical tool as claimed in any preceding claim, and a standard surgical instrument.

20. A surgical system as claimed in claim 19, wherein the surgical tool is coupled to the standard surgical instrument.

21. A surgical system as claimed in claim 19 or claim 20, wherein the surgical instrument comprises a pair of forceps or a pair of scissors.

22. A surgical system as claimed in any of claims 19 to 21 , wherein the surgical instrument comprises jaws on which the grasping surfaces are formed.

23. A surgical system as claimed in claim 22, wherein a fluorescence excitation source is provided on one jaw and a fluorescence detector is provided on another jaw.

24. A surgical system as claimed in claim 22, wherein the fluorescence excitation source and the detector are provided on the same jaw.

25. A surgical system as clamed in claim 24, wherein the fluorescence excitation source and the detector are provided on one jaw, and a non-fluorescence-based excitation source and/or detector is/ are provided on the another jaw.

26. A surgical system as claimed in claim 25, wherein the non-fluorescence-based excitation source and/or detector are/is configured to provide an additional sensing modality selected from one of ultrasound, Raman spectroscopy, optoacoustic imaging, absorption/ reflectance imaging, optical coherence tomography and/ or magnetic resonance imaging sensing modalities.

27. The surgical system as claimed in any of claims 23 to 26, wherein the fluorescence excitation source and/or the detector comprises one or more optical fibres for fluorescence component excitation and/or signal detection, the fibres coupling the excitation source and/or the detector of the surgical tool with an excitation source and/or detector, respectively, positioned apart from the surgical tool.

28. A surgical system as claimed in any of claims 19 to 27, wherein at least a part of the housing of the surgical tool is mounted in at least one cavity of the surgical instrument.

29. A surgical system as claimed in claim 27 when dependent on claim 22, wherein the excitation source is mounted in a cavity in one jaw of the surgical instrument and the detector is mounted in a cavity in another jaw of the surgical instrument.

30. A surgical system as claimed in claim 28 or claim 29, wherein the at least a part of the surgical tool is mounted into the at least one cavity on the surgical instrument using a push-fit connection, sliding connection and/or or clip connection.

31. A surgical system as claimed in any of claims 19 to 30, wherein the surgical instrument comprises an articulation mechanism.

32. A surgical system as claimed in any of claims 19 to 31 , wherein the surgical instrument is configured for use during laparoscopic surgery, optionally robotic laparoscopic surgery.

33. The surgical system as claimed in any of claims 19 to 32, wherein at least a part of the system is configured to be sterilizable and/or disposable.

34. A surgical system as claimed in of any of claims 19 to 33, further comprising a white light source for illuminating a subject tissue under white light conditions.

35. A surgical system as claimed in claim 34, further comprising; a signal processing device communicatively coupled to the signal transmission device of the surgical tool, wherein the surgical system is operable to irradiate a subject tissue in which at least one fluorescent component is present using a fluorescence excitation source provided on the surgical tool to enable continuous tissue characterisation and visualisation when the subject tissue is illuminated under white light conditions.

36. The surgical system of claim 35, wherein the tissue characterisation is associated with identification of different fluorescent components within the subject tissue based on the fluorescence emission from the subject tissue.

37. The surgical system of claim 34 or claim 36, wherein a tissue characteristic is one or more of a tissue type, tumour cell(s), inflammation, lymphatic structures, nerve(s), bile ducts, ureters and/ or blood vessel(s).

38. The surgical system of any of claims 22 to 37, wherein the signal processing device is configured to determine the tissue characteristic by comparing the fluorescence emission from the subject tissue detected by the detector with a reference fluorescence emission spectrum and/ or with a previously collected data set of fluorescence emissions corresponding to particular tissue characteristics.

39. The surgical system of any of claims 22 to 38, wherein the fluorescence emission detected by the detector comprises a single fluorescent emission or a plurality of fluorescent emissions.

40. The surgical system of any of claims 34 to 39, wherein the signal from the detector comprises one or more of an audio signals, a quantitative signal and/or a visual signal.

41. The surgical system of any of claims 19 to 40, further comprising a display means configured to display a visual representation of at least a part of the subject tissue.

42. The surgical system of any of claims 19 to 41 , wherein the signal(s) are indicative of different imaging signatures.

43. The surgical system of any of claims 19 to 42, wherein the surgical system is configured for use during laparoscopic surgery, optionally robot assisted laparoscopic surgery.

44. The surgical system of any of claims 19 to 43, wherein at least a part of the system is configured to be sterilizable and/or disposable.

45. A method of performing tissue visualisation and characterisation using the surgical tool of any of claims 1 to 18 and/or the surgical system of any of claims 19 to 44.

46. A method of performing tissue visualisation and characterisation comprising; illuminating a subject tissue which comprises a fluorescent component with a fluorescence excitation source; detecting a signal from the subject tissue indicative of a presence of the fluorescent component in the subject tissue; processing the signal to determine a tissue characteristic based on a fluorescence response of the subject tissue; wherein processing of the signal to determine a tissue characteristic is continuous irrespective of whether the subject tissue is illuminated under a white light mode or a fluorescence mode.

47. The method of claim 46, performed using the surgical tool of any of claims 1 to 18 and/or using the surgical system of any of claims 19 to 44.

48. The method of claim 46 or claim 47 when the surgical instrument comprises jaws, further comprising a step of combining the signal with a visual representation of at least a part of the subject tissue as seen along a length axis of at least one of the jaws.