Identification of human tissue using optical spectroscopy

• US 20040044287A1
• Filed: 04/22/2002
• Published: 03/04/2004
• Est. Priority Date: 03/31/2000
• Status: Abandoned Application

• Current Assignee: Anita Mahadevan-Jansen, Jansen E. Duco, Steven A. Toms, Wei-Chiang Lin
• Original Assignee: Anita Mahadevan-Jansen, Jansen E. Duco, Steven A. Toms, Wei-Chiang Lin
• Inventors: Lin, Wei-Chiang, Toms, Steven A., Mahadevan-Jansen, Anita, Jansen, E. Duco
• Application Number:
  US10/360,776
• Publication Number:
  US 20040044287A1
• Time in Patent Office: Days
• US Class Current: 600/475
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: G01N 2021/6484 Optical fibres
• CPC Class Codes: G01N 21/6486 Measuring fluorescence of biological material, e.g. DNA, RNA, cells G01N21/6428 takes precedence

Abstract

Tissue types (e.g. tumorous or normal) are determined using optical spectroscopy. Autofluorescence and diffuse reflectance spectra are generated by separately illuminating a tissue surface area with monochromatic light and white light. A peak in autofluorescence intensity (F) is provided around 460 nm from both from normal and tumorous human brain tissue with 337 nm monochromatic light excitation. Separation between white/gray matter and brain tumors is provided by certain combined F-Rd spectrum numerical values, especially certain ratios of F and Rd between 400 nm-600 nm. Numerical values based on certain combinations of unequal exponential powers of F and Rd are essentially unaffected by the superficial blood contamination. In addition, diffuse reflectance intensity (Rd) between 650 nm and 800 nm from white/gray matter was significantly stronger than that from primary and secondary brain tumors and is used with the combined spectrum numerical value to enhance accurate determinations.

Claims

1. A method for optically identifying human tissue type comprising the steps of:

illuminating a surface area of tissue to be identified with a source of white light and gathering diffuse reflectance light returned from the illuminated tissue area;

illuminating the surface area of the tissue to be identified with a source of monochromatic light and gathering autofluorescent light emitted by the tissue area in response to the monochromatic light illumination, the illumination and gathering of the diffuse reflectance light and the autofluorescent light occurring in either order;

generating a numerical value based at least in part upon a first ratio of a value of intensity of the diffuse reflectance light gathered from the illuminated tissue area and a value of intensity of the autofluorescent light gathered from the illuminated tissue area; and

using the numerical value to identify the type of tissue of the area illuminated.

2. The method according to claim 1 wherein the numerical value is used to distinguish between tumorous and non-tumorous tissue

3. The method according to claim 2 wherein the numerical value is used to distinguish between tumorous brain tissue and normal brain tissue.

4. The method according to claim 1 wherein the monochromatic light illuminating step comprises illuminating the tissue surface with coherent light at a wavelength of about 330 nm.

5. The method according to claim 1 wherein the first ratio is generated using the value of the intensity of the diffuse reflectance light at one wavelength and the value of the intensity of the autofluorescent light at the one wavelength.

6. The method according to claim 5 wherein the one wavelength of the intensity of the diffuse reflectance light and the intensity of the autofluorescent light used in the first ratio is selected from a range of between 300 nm and 700 nm.

7. The method according to claim 5 wherein the one wavelength of the intensity of the diffuse reflectance light and the intensity of the autofluorescent light used in the first ratio is selected from a range of between 400 nm and 600 nm.

8. The method according to claim 5 wherein the one wavelength of the intensity of the diffuse reflectance light and the intensity of the autofluorescent light used in the first ratio is selected from a range of 450 nm. to 470 nm.

9. The method according to claim 5 wherein the one wavelength of the intensity of the diffuse reflectance light and the intensity of the autofluorescent light used in the first ratio is about 460 nm.

10. The method according to claim 5 further comprising the step of identifying a second value of intensity of the diffuse reflectance light from the illuminated area at a second wavelength different from the one wavelength of the diffuse reflectance intensity used in the first ratio and wherein the using step further comprises using the second intensity value with the first ratio to identity the type of tissue illuminated.

11. The method according to claim 10 further comprising the steps of identifying a second value of intensity of the autofluorescent light from the illuminated area at the second wavelength, generating a second ratio including the second value of intensity of the diffuse reflectance light with the second value of intensity of the autofluoresecent light and combining the first and second ratios to provide the numerical value.

12. The method according to claim 1 wherein the value of the intensity of the diffuse reflectance light used to generate the first ratio is an other than zero exponential value of the intensity of the diffuse reflectance light other than zero and different from an other than zero exponential value of the intensity of autofluorescent light used to generate the first ratio.

13. The method according to claim 12 wherein the first ratio is generated using the value of the intensity of the diffuse reflectance light at only one wavelength and the value of the intensity of the autofluorescent light at the one wavelength.

14. The method according to claim 13 wherein the one wavelength is selected from a range of between 400 nm. to 600 nm.

15. The method according to claim 14 wherein the one wavelength is about 460 nm.

16. The method according to claim 13 further comprising the step of identifying a second value of intensity of the diffuse reflectance light from the illuminated area at a second wavelength different from the one wavelength of the diffuse reflectance intensity used in the first ratio and wherein the using step further comprises using the second intensity value with the first ratio to identity the type of tissue illuminated.

17. The method according to claim 16 wherein the intensity of the diffuse reflectance light used to generate the first ratio has a blood absorption coefficient dependent exponential value (h) greater than an exponential value of the intensity of the autofluorescent light used to generate the first ratio.

18. The method according to claim 17 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is about twenty five times or less than the exponential value of the autofluorescent light used to generate the first ratio.

19. The method according to claim 17 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is about twelve times or less than the exponential value of the autofluorescent light used to generate the first ratio.

20. The method according to claim 17 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is about four times or less than the exponential value of the autofluorescent light used to generate the first ratio.

21. The method according to claim 17 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is less than two times of the exponential value of the autofluorescent light used to generate the first ratio.

22. The method according to claim 17 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is between about one and two-thirds the exponential value of the autofluorescent light used to generate the first ratio.

23. The method according to claim 12 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is greater than the exponential value of the autofluorescent light used to generate the first ratio.

24. The method according to claim 23 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is about twenty-five times or less than the exponential value of the autofluorescent light used to generate the first ratio.

25. The method according to claim 23 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is about twelve times or less than the exponential value of the autofluorescent light used to generate the first ratio.

26. The method according to claim 23 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is less than two times of the exponential value of the autofluorescent light used to generate the first ratio.

27. The method according to claim 23 wherein the exponential value of the diffuse reflectance light used to generate the first ratio is about one and two-thirds the exponential value of the autofluorescent light used to generate the first ratio.

28. The method according to claim 1 wherein an exponential value of the intensity of the diffuse reflectance light is used to generate the first ratio and is different from zero and from an exponential value of the intensity of the autofluorescent light used to generate the first ratio.

29. The method according to claim 1 wherein the first ratio is generated using at least one exponential value other than unity and other than zero of at least one of the intensity of the diffuse reflectance light and the intensity of the autofluorescent light, the at least one exponential value being selected to reduce variation in the numerical value caused by the presence of blood contamination of the surface area being illuminated.

30. The method according to claim 1 further comprising the step of identifying a second value of intensity of the diffuse reflectance light from the illuminated area at a second wavelength different from any wavelength of the diffuse reflectance intensity used in the first ratio and wherein the using step further comprises using the second intensity value with the first ratio to identity the type of tissue illuminated.

31. The method according to claim 30 further comprising the steps of identifying a second value of intensity of the autofluorescent light from the illuminated area at the second wavelength and generating a second ratio including the second value of intensity of the diffuse reflectance light with the second value of the autofluorescent light and using the second ratio with the first ratio to generate the numerical value.

32. The method according to claim 30 wherein the one wavelength is selected from a range of between 300 nm 700 nm.

33. The method according to claim 30 wherein the one wavelength is selected from a range of between 300 nm. to 600 nm.

34. The method according to claim 30 wherein the one wavelength is selected from a range of between 400 nm to 600 nm.

35. The method according to claim 30 wherein the one wavelength is about 460 nm.

36. The method according to claim 1 wherein the generating step further includes:

generating a second ratio of a second value of intensity of the diffuse reflectance light from the illuminated area at a second wavelength different from any wavelength of the diffuse reflectance light intensity used in the first ratio and of a second value of intensity of the autofluorescent light from the illuminated area at the second wavelength; and

combining the second ratio with the first ratio to generate the numerical value of the illuminated area.

37. The method according to claim 36 wherein an exponential value other than zero of the intensity of the diffuse reflectance light is used to generate at least the first ratio and is different from an exponential value other than zero of the intensity of the autofluorescent light used to generate the first ratio.

38. The method according to claim 37 wherein an exponential value other than zero of the intensity of the diffuse reflectance light is used to generate the second ratio and is different from an exponential value other than zero of the intensity of the autofluorescent light used to generate the second ratio.

39. The method according to claim 38 wherein the exponential value of the intensity of the diffuse reflectance light used to generate the first ratio is the same as the exponential value of the diffuse reflectance light used to generate the second ratio.

40. The method according to claim 38 wherein the exponential value of the autofluorescent light used to generate the first ratio is the same as the exponential value of the autofluorescent light used to generate the second ratio.

41. The method according to claim 38 wherein the exponential value of the autofluorescent light used to generate the first ratio is twice the exponential value of the diffuse reflectance light used to generate the first ratio.

42. The method according to claim 36 wherein the exponential values of the autofluorescent and diffuse reflectance intensities used in the first and second ratios are independent of each of the first and second wavelengths.

43. The method according to claim 12 wherein the exponential value of the diffuse reflectance light is related, at least in part, to the first wavelength.

44. The method according to claim 12 wherein the exponential value of the diffuse reflectance light is related, at least in part, to a wavelength of the monochromatic light.