Imaging system for detecting diseased tissue using native fluorsecence in the gastrointestinal and respiratory tract

• US 5,647,368 A
• Filed: 02/28/1996
• Issued: 07/15/1997
• Est. Priority Date: 02/28/1996
• Status: Expired due to Term

• Current Assignee: Novadaq Technologies, Inc. (Stryker Corporation)
• Original Assignee: Xillix Technologies Corp.
• Inventors: Cline, Richard W., Zeng, Haishan, MacAulay, Calum E., Jaggi, Bruno W.
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): MANTIS MERCADER, ELENI M
• Application Number:
  US08/608,185
• Time in Patent Office: 503 Days
• Field of Search: 128/664, 128/665, 128/633, 128/634, 356/433, 356/435, 356/342, 356/343, 356/338, 356/432, 250/330-334, 250/461.2, 250/574-575, 250/358.1
• US Class Current: 600/476
• CPC Class Codes: A61B 1/00009 of image signals during a use of endoscope
• CPC Class Codes: A61B 1/00186 with imaging filters
• CPC Class Codes: A61B 1/042 characterised by a proximal camera, e.g. a CCD camera
• CPC Class Codes: A61B 1/043 for fluorescence imaging
• CPC Class Codes: A61B 1/0646 with illumination filters
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/42 Detecting, measuring or recording for evaluating the gastrointestinal, the endocrine or the exocrine systems A61B1/00, A61B5/4857, A61B5/486, A61B5/4866, A61B5/4869 take precedence
• CPC Class Codes: A61B 5/4255 Intestines, colon or appendix

Abstract

A system for detecting cancerous or precancerous lesions directs light produced from a mercury arc lamp into an illumination guide of an endoscope. Autofluorescence light produced by the tissue under examination is divided into red and green spectral bands by a dichroic mirror. Light in the red and green spectral band is applied to a pair of image intensified CCD cameras. The output of the camera that receives light in the red spectral band is coupled to a red video input of a color video monitor. Light produced by the camera that receives light in the green spectral band is coupled to the blue and green video inputs of the video monitor. The system produces a false color display, whereby healthy tissue appears cyan in color and cancerous or precancerous lesions appear reddish in color. The image displayed allows the operator to see the lesions within the context of the underlying tissue structures. The color contrast is adjustable to account for the autofluorescence property changes from patient to patient and from location to location.

Claims

1. A system for examining tissue to detect the presence of cancerous or precancerous tissue, comprising:

an endoscope;

a substantially monochromatic light source for producing excitation light at an excitation wavelength that will cause the tissue under examination to produce autofluorescence light, the light source including;

a) a lamp that produces excitation light;

b) a collecting mirror positioned about the lamp for collecting the excitation light produced by the lamp and directing the excitation light outwardly of the collecting mirror,

c) a first dichroic mirror positioned to receive the excitation light collected by the collecting mirror and to filter the excitation light;

d) a first lens positioned to receive the filtered excitation light reflected from the first dichroic mirror in order to produce a substantially parallel beam of excitation light;

e) a color filter positioned to receive the parallel beam of excitation light, the color filter operating to filter light having wavelengths not at the excitation wavelength from the parallel beam of excitation light; and

f) a second lens positioned to receive the filtered beam of excitation light that has passed through the color filter, the second lens focusing the excitation light into the endoscope in order to excite the tissue under examination;

collecting means for gathering reflected excitation light and autofluorescence light produced by the tissue under examination;

a second dichroic mirror positioned to receive the gathered, reflected excitation light and the autofluorescence light, the second dichroic mirror dividing the autofluorescence light into a first beam having wavelengths where an intensity of the autofluorescence light for abnormal tissue is substantially different from normal tissue and a second beam where an intensity of the autofluorescence light for abnormal tissue is substantially the same as normal tissue;

a first and second camera for producing a first and second autofluorescence image signal of the tissue under examination;

the first camera receiving the first beam of autofluorescence light and the second camera receiving the second beam of autofluorescence light; and

a color monitor having color video inputs, wherein the first autofluorescence image signal is coupled to a first color video input and the second autofluorescence image signal is coupled to another of the color video inputs, the color monitor producing a false color display whereby normal tissue and abnormal tissue appear as contrasting colors on the color monitor.

2. The system of claim 1, wherein the lamp is a mercury arc lamp.

3. The system of claim 2, wherein the collecting mirror is an elliptical mirror positioned so that the mercury arc lamp is at a foci of the elliptical mirror.

4. The system of claim 2, wherein the excitation wavelength is 436 nanometers and the first dichroic mirror reflects excitation light having wavelengths between 350 and 450 nanometers.

5. The system of claim 1, wherein the color filter is an interference bandpass filter that passes excitation light having wavelengths between 420 and 450 nanometers.

6. The system of claim 1, further comprising a second bandpass disposed between the second dichroic mirror and the first camera, the second bandpass filter passing autofluorescence light having wavelengths between 490 and 560 nanometers.

7. The system of claim 1, further comprising a red long pass filter disposed between the second dichroic mirror and the second camera, the long pass filter having a cutoff wavelength of 630 nanometers.

8. The system of claim 1, wherein each of the autofluorescence image signals has a gain, the system further comprising a control for adjusting the gain of one of the first or second autofluorescence signals produced by the first or second cameras, as a function of the gain of the other of the first or second autofluorescence image signals.

9. The system of claim 1, wherein the color monitor is an RGB monitor having red, green and blue color video inputs.

10. The system of claim 1, wherein the first and second cameras are image intensified CCD cameras.

11. Apparatus for imaging diseases in tissue using autofluorescence comprising:

a light source for generating excitation light that will cause tissue to generate characteristic autofluorescence light;

means for illuminating tissue with the excitation light thereby exciting tissue to emit said characteristic autofluorescence light;

collecting means for gathering reflected excitation light and said characteristic emitted autofluorescence light produced by the tissue;

a dichroic mirror positioned to receive the reflected excitation light and the emitted autofluorescence light collected by the collecting means, the dichroic mirror operating to separate the spectral components of said autofluorescence light into at least a first spectral band including the reflected excitation light and emitted autofluorescence light having wavelengths where an autofluorescence intensity for abnormal tissue is substantially different from normal tissue and a second spectral band different from said first spectral band including the emitted autofluorescence light having wavelengths where an autofluorescence intensity for abnormal tissue is substantially similar to normal tissue;

a first optical filter positioned to receive the light within the first spectral band, said first filter operating to remove the reflected excitation light from the light within the first spectral band;

a second optical filter positioned to receive the light within the second spectral band;

a first image intensified CCD camera for receiving the autofluorescence light within the first spectral band and for producing a first autofluorescence image signal of the tissue;

a second image intensified CCD camera for receiving the autofluorescence light within the second spectral band and for producing a second autofluorescence image signal of the tissue;

a control for adjusting the gain of one of the first or second autofluorescence image signals produced by the intensified CCD cameras as a function of the gain of the other of the first or second autofluorescence image signals; and

a color monitor having at least a first and a second color input, whereby the first color input is coupled to receive the first autofluorescence image signal and the second color input is coupled to receive the second autofluorescence image signal to create a combined, display image in which said abnormal and normal tissue are displayed on the color monitor.

12. The system of claim 11, further comprising a control for adjusting the function by which the gain of the first or second autofluorescence image signal is dependent on the gain of the other of the first or second autofluorescence image signal.

13. A system for detecting cancerous or precancerous tissue comprising:

a substantially monochromatic light source for producing excitation light that causes tissue under examination to produce autofluorescence light;

an endoscope positioned to receive the excitation light and to direct the excitation light into an internal body cavity of a patient and onto the tissue under examination;

means for collecting the autofluorescence light produced by the tissue under examination;

a beam splitter for dividing the collected autofluorescence light into a first beam having wavelengths where an intensity of the autofluorescence light from abnormal tissue is substantially different than from normal tissue and a second beam having wavelengths where an intensity of the autofluorescence light from abnormal tissue is substantially the same as from normal tissue;

a first and second image intensified or non-intensified CCD camera for receiving the first and second beams of autofluorescence light, respectively, the first and second image intensified or non-intensified CCD cameras producing a first and second autofluorescence image signal; and

a color monitor having a red, blue and green color input, the red color input being connected to receive one of the first or second autofluorescence image signals and the blue and green color inputs are connected to receive the other of the first or second autofluorescence image signals in order to produce a display having a color that is representative of a ratio of a magnitude of the first autofluorescence signal and the second autofluorescence signal, said display providing an indication of whether the tissue is normal or abnormal.