Method and apparatus for intraoperative nerve visualization using polarized diffuse reflectance spectroscopy and applications of same

Abstract

An apparatus or handheld probe for intraoperative nerve identification and/or visualization of a target of interest of a living subject includes a light source for emitting a beam of light to illuminate a target of interest; a light delivering means for delivering the beam of light emitted from the light source onto the target of interest so as to illuminate the target of interest therewith; and an imaging head positioned over the target of interest for acquiring polarized diffuse reflectance spectral images of light from the illuminated target of interest responsive to the illumination, for identifying and/or visualizing one or more nerves in the target of interest.

What is claimed is: 
     
         1 . An apparatus for intraoperative nerve identification and/or visualization of a target of interest of a living subject, comprising:
 a light source for emitting a beam of light to illuminate a target of interest;   a light delivering means for delivering the beam of light emitted from the light source onto the target of interest so as to illuminate the target of interest therewith; and   an imaging head positioned over the target of interest for acquiring polarized diffuse reflectance spectral (DRS) images of light from the illuminated target of interest responsive to the illumination, for identifying and/or visualizing one or more nerves in the target of interest.   
     
     
         2 . The apparatus of  claim 1 , wherein the light source is a broadband light source for emitting the beam of light in a wavelength range of about 100-1200 nm. 
     
     
         3 . The apparatus of  claim 1 , wherein the beam of light emitted from the light source is polarized either inherently or through polarizers with variable axes of transmission delivered to the target of interest. 
     
     
         4 . The apparatus of  claim 1 , wherein the light delivering means comprises one or more fibers and is configured such that
 light delivered onto the target of interest from at least one of the one or more fibers is unpolarized light; or   light delivered onto the target of interest from at least one of the one or more fibers is polarized light having fixed and/or variable polarizations; or   light delivered onto the target of interest from one of the one or more fibers is unpolarized light and light delivered onto the target of interest from the others of the one or more fibers is polarized light having fixed and/or variable polarizations.   
     
     
         5 . The apparatus of  claim 1 , wherein the light delivering means comprises one or more lenses configured to deliver the beam of light emitted from the light source onto the target of interest. 
     
     
         6 . The apparatus of  claim 5 , wherein the light delivering means further comprises one or more wave plates configured to polarize the beam of light emitted from the light source in polarized light having fixed and/or variable polarizations. 
     
     
         7 . The apparatus of  claim 1 , wherein the imaging head comprises:
 a detector disposed in a top portion of the image head for acquiring the DRS images;   a tunable filter positioned in a bottom portion of the image head in an optical path for collecting light from the illuminated target of interest; and   a lens positioned between the tunable filter and the detector in the optical path for focusing the collected light to the detector.   
     
     
         8 . The apparatus of  claim 7 , wherein the detector comprises at least one camera. 
     
     
         9 . The apparatus of  claim 8 , wherein the at least one camera comprises at least one charge-coupled device (CCD) camera, at least one complementary metal oxide semiconductor (CMOS) camera, at least one photosensor array, or a combination thereof. 
     
     
         10 . The apparatus of  claim 8 , wherein the at least one camera comprises at least one infrared camera and/or at least one near-infrared (NIR) camera. 
     
     
         11 . The apparatus of  claim 7 , wherein the tunable filter is an optical filter that uses electronically controlled liquid crystal (LC) elements to transmit a selectable wavelength of light and exclude others, with fixed and/or variable polarizations. 
     
     
         12 . The apparatus of  claim 11 , wherein the LC elements comprise switchable LC wave plates. 
     
     
         13 . The apparatus of  claim 7 , wherein the tunable filter is a dispersion based filter that produces a spatially distributed continuous wavelength spectrum that is operably sampled for wavelengths including selecting wavelengths, not restricted to individual but also extending to a selection of a full wavelength spread spectrum. 
     
     
         14 . The apparatus of  claim 7 , wherein the tunable filter comprises variable spectral bandpass filters, variable polarization filters, or a combination thereof. 
     
     
         15 . The apparatus of  claim 7 , wherein the lens is an adjustable focus lens. 
     
     
         16 . The apparatus of  claim 7 , wherein the light source is operably modulated by a lock-in scheme or a transistor-transistor logic (TTL) trigger for providing a trigger to sequence and/or initiate data collection for enabling operations of the detector in normal and/or external lighting conditions including room lights. 
     
     
         17 . The apparatus of  claim 7 , wherein the imaging head further comprises one or more lenses positioned between the target of the interest and the tunable filter for focusing the light from the illuminated target of interest to the tunable filter. 
     
     
         18 . The apparatus of  claim 1 , further comprising a controller configured to coordinately operate the light delivering means to deliver the beam of light onto the target of interest and the image head to acquire the DRS images of the light from the illuminated target of interest, to receive the acquired images from the detector, and to process the acquired images to identify and visualize nerve in the target of interest. 
     
     
         19 . The apparatus of  claim 18 , wherein the controller is further configured to provide, based on the processed images, an aural or tactile nerve proximity indication that allows a surgeon to spatially and manually interrogate locations prior to and/or during execution of tissue surgical manipulations. 
     
     
         20 . The apparatus of  claim 19 , wherein the controller is further configured to provide visual, aural and/or tactile feedbacks including vibration and/or buzzing alerts. 
     
     
         21 . The apparatus of  claim 18 , further comprising a display for displaying the processed images and/or means for projecting the processed images onto the intraoperative field of view. 
     
     
         22 . A probe for intraoperative nerve identification and/or visualization of a target of interest of a living subject, comprising:
 a light delivering means coupled with a light source for delivering a beam of light emitted from the light source onto a target of interest so as to illuminate the target of interest therewith;   a light collecting means positioned over the target of interest for collecting light from the illuminated target of interest responsive to the illumination; and   an imaging means positioned over the target of interest coupled with the light collecting means for acquiring polarized diffuse reflectance spectral (DRS) images of light from the illuminated target of interest responsive to the illumination, for identifying and/or visualizing one or more nerves in the target of interest.   
     
     
         23 . The probe of  claim 22 , wherein the light source is a built-in broadband light source or an external broadband light source for emitting the beam of light in a wavelength range of about 100-1200 nm. 
     
     
         24 . The probe of  claim 22 , wherein the beam of light emitted from the light source is polarized either inherently or through polarizers with variable axes of transmission delivered to the target of interest. 
     
     
         25 . The probe of  claim 22 , wherein the light delivering means comprises one or more fibers and is configured such that
 light delivered onto the target of interest from at least one of the one or more fibers is unpolarized light; or   light delivered onto the target of interest from at least one of the one or more fibers is polarized light having fixed and/or variable polarizations; or   light delivered onto the target of interest from one of the one or more fibers is unpolarized light and light delivered onto the target of interest from the others of the one or more fibers is polarized light having fixed and/or variable polarizations.   
     
     
         26 . The probe of  claim 22 , wherein the light delivering means comprises one or more lenses configured to deliver the beam of light emitted from the light source onto the target of interest. 
     
     
         27 . The probe of  claim 26 , wherein the light delivering means further comprises one or more wave plates configured to polarize the beam of light emitted from the light source in polarized light having fixed and/or variable polarizations. 
     
     
         28 . The probe of  claim 22 , wherein the light collecting means comprises:
 a tunable filter for collecting light from the illuminated target of interest; and   a lens positioned for focusing the collected light to the imaging means.   
     
     
         29 . The probe of  claim 28 , wherein the tunable filter is an optical filter that uses electronically controlled liquid crystal (LC) elements to transmit a selectable wavelength of light and exclude others, with fixed and/or variable polarizations. 
     
     
         30 . The probe of  claim 29 , wherein the LC elements comprise switchable LC wave plates. 
     
     
         31 . The probe of  claim 28 , wherein the tunable filter is a dispersion based filter that produces a spatially distributed continuous wavelength spectrum that is operably sampled for wavelengths including selecting wavelengths, not restricted to individual but also extending to a selection of a full wavelength spread spectrum. 
     
     
         32 . The probe of  claim 28 , wherein the tunable filter comprises variable spectral bandpass filters, variable polarization filters, or a combination thereof. 
     
     
         33 . The probe of  claim 28 , wherein the lens is an adjustable focus lens. 
     
     
         34 . The probe of  claim 28 , wherein the light collecting means further comprises one or more lenses positioned between the target of the interest and the tunable filter for focusing the light from the illuminated target of interest to the tunable filter. 
     
     
         35 . The probe of  claim 28 , wherein the light collecting means further comprises one or more fibers each having one end coupled to the tunable filter and an opposite, working end operably positioned proximate to the target of interest to collect the light from the illuminated target of interest to the tunable filter. 
     
     
         36 . The probe of  claim 22 , wherein the imaging means comprises a detector acquiring the DRS images. 
     
     
         37 . The probe of  claim 36 , wherein the detector comprises at least one camera. 
     
     
         38 . The probe of  claim 37 , wherein the at least one camera comprises at least one charge-coupled device (CCD) camera, at least one complementary metal oxide semiconductor (CMOS) camera, at least one photosensor array, or a combination thereof. 
     
     
         39 . The probe of  claim 37 , wherein the at least one camera comprises at least one infrared camera and/or at least one near-infrared (NIR) camera. 
     
     
         40 . The probe of  claim 36 , wherein the light source is operably modulated by a lock-in scheme or a transistor-transistor logic (TTL) trigger for providing a trigger to sequence and/or initiate data collection for enabling operations of the detector in normal and/or external lighting conditions including room lights. 
     
     
         41 . The probe of  claim 22 , further comprising a controller configured to coordinately operate the light delivering means to deliver the beam of light onto the target of interest, the light collecting means to collect the light from the illuminated target of interest, and the imaging means to acquire the DRS images of the light from the illuminated target of interest, to receive the acquired images from the detector imaging means, and to process the acquired images to identify and visualize nerve in the target of interest. 
     
     
         42 . The probe of  claim 41 , wherein the controller is further configured to provide, based on the processed images, an aural or tactile nerve proximity indication that allows a surgeon to spatially and manually interrogate locations prior to and/or during execution of tissue surgical manipulations. 
     
     
         43 . The probe of  claim 42 , wherein the controller is further configured to provide visual, aural and/or tactile feedbacks including vibration and/or buzzing alerts. 
     
     
         44 . The probe of  claim 41 , further comprising a display for displaying the processed images and/or means for projecting the processed images onto the intraoperative field of view. 
     
     
         45 . The probe of  claim 22 , being a handheld probe. 
     
     
         46 . A method for intraoperative nerve identification and/or visualization of a target of interest of a living subject, comprising:
 delivering a beam of light onto a target of interest so as to illuminate the target of interest therewith;   acquiring polarized diffuse reflectance spectral (DRS) images of light from the illuminated target of interest responsive to the illumination; and   processing the acquired DRS images to identify and visualize nerve in the target of interest.   
     
     
         47 . The method of  claim 46 , wherein the beam of light delivered onto the target of interest is in a wavelength range of about 100-1200 nm. 
     
     
         48 . The method of  claim 46 , wherein the beam of light delivered onto the target of interest is unpolarized light, polarized light with fixed and/or variable polarizations, or a combination thereof. 
     
     
         49 . The method of  claim 46 , wherein the acquiring step further comprises:
 selectively transmitting a wavelength of the light from the illuminated target of interest;   acquiring a DRS image of the transmitted light; and   repeating the transmitting step and the acquiring step over a predetermined wavelength range with a predefined resolution.   
     
     
         50 . The method of  claim 49 , wherein the predetermined wavelength range is from about 200 nm to about 1000 nm, and the predefined resolution is about 1 nm, about nm, about 3 nm, about 4 nm, about 5 nm, or 6 nm. 
     
     
         51 . The method of  claim 49 , wherein the acquiring step further comprises filtering the light from the illuminated target of interest with polarizers so that the light is polarized with fixed and/or variable polarizations. 
     
     
         52 . The method of  claim 46 , wherein the acquiring step comprises acquiring background images without delivering the beam of light onto the target of interest before acquiring images of the illuminated target of interest, and the processing step comprises subtracting the background images from the acquired images of the illuminated target of interest. 
     
     
         53 . The method of  claim 46 , wherein the processing step comprises identifying spectral markers from spectra averaged spectra of the plurality of living subjects for each tissue type, wherein each spectral marker at a wavelength provides a statistically significant difference and biological justification for a corresponding type of tissue, and wherein the averaged spectra for each tissue type are normalized to a peak at about 690 nm, or a wavelength of significance. 
     
     
         54 . The method of  claim 53 , wherein the processing step further comprises
 comparing intensity ratios between the wavelengths of the spectral markers and the peak wavelength at about 690 nm, or a wavelength of significance, to differentiate tissue types;   classifying tissues based on thresholds of the intensity ratios; and   mapping, using the thresholds, the tissue distribution across the DRS images on a pixel by pixel basis.   
     
     
         55 . The method of  claim 54 , further comprising displaying the tissue distribution across the DRS images and/or projecting the tissue distribution onto the intraoperative field of view so as to enable intraoperative identification and/or visualization of one or more nerves in the target of interest. 
     
     
         56 . The method of  claim 46 , further comprising providing a trigger to sequence and/or initiate data collection for enabling the acquiring operation in normal and/or external lighting conditions including room lights. 
     
     
         57 . A non-transitory tangible computer-readable medium storing instructions which, when executed by one or more processors, cause the method of  claim 46  to be performed. 
     
     
         58 . The non-transitory tangible computer-readable medium of  claim 57 , wherein the acquiring step further comprises:
 selectively transmitting a wavelength of the light from the illuminated target of interest;   acquiring a DRS image of the transmitted light; and   repeating the transmitting step and the acquiring step over a predetermined wavelength range with a predefined resolution.   
     
     
         59 . The non-transitory tangible computer-readable medium of  claim 58 , wherein the acquiring step further comprises filtering the light from the illuminated target of interest with polarizers so that the light is polarized with fixed and/or variable polarizations. 
     
     
         60 . The non-transitory tangible computer-readable medium of  claim 57 , wherein the acquiring step comprises acquiring background images without delivering the beam of light onto the target of interest before acquiring images of the illuminated target of interest, and the processing step comprises subtracting the background images from the acquired images of the illuminated target of interest. 
     
     
         61 . The non-transitory tangible computer-readable medium of  claim 57 , wherein the processing step comprises identifying spectral markers from spectra averaged spectra of the plurality of living subjects for each tissue type, wherein each spectral marker at a wavelength provides a statistically significant difference and biological justification for a corresponding type of tissue, and wherein the averaged spectra for each tissue type are normalized to a peak at about 690 nm, or some other wavelength of significance. 
     
     
         62 . The non-transitory tangible computer-readable medium of  claim 61 , wherein the processing step further comprises
 comparing intensity ratios between the wavelengths of the spectral markers and the peak wavelength at about 690 nm, or a wavelength of significance, to differentiate tissue types;   classifying tissues based on thresholds of the intensity ratios; and   mapping, using the thresholds, the tissue distribution across the DRS images on a pixel by pixel basis.   
     
     
         63 . The non-transitory tangible computer-readable medium of  claim 62 , wherein the method further comprises displaying the tissue distribution across the DRS images and/or projecting the tissue distribution onto the intraoperative field of view so as to intraoperative identification and/or visualization of one or more nerves in the target of interest. 
     
     
         64 . The non-transitory tangible computer-readable medium of  claim 57 , wherein the method further comprises providing a trigger to sequence and/or initiate data collection for enabling the acquiring operation in normal and/or external lighting conditions including room lights.