Methods of enhanced light transmission through turbid biological media

• US 6,275,726 B1
• Filed: 05/15/1998
• Issued: 08/14/2001
• Est. Priority Date: 05/15/1997
• Status: Expired due to Term

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Barton, Jennifer K., Chan, Eric K., Welch, Ashley J.
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): SHAW, SHAWNA JEANNINE
• Application Number:
  US09/079,991
• Time in Patent Office: 1,187 Days
• Field of Search: 600/473, 600/476, 600/310, 600/316, 604/19, 604/20, 604/289, 424/400, 424/427, 356/39, 356/432, 356/337
• US Class Current: 600/476
• CPC Class Codes: A61B 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence
• 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 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters

Abstract

A new process to increase light transmission in biological tissue has been developed. The technique involves temporarily replacing tissue water with a fluid that has a refractive index closer to that of inter/intra cellular components. Subsequently, the amount of index mis-match between these components and the fluid environment is temporarily decreased. This lowers the amount of random reflection and refraction which also reduces light scattering. In addition, the infrared absorption is reduced when the fluid has a lower absorption coefficient than water. Furthermore, this process is reversible; thus creating a transient window to enhance light transmission for therapeutic and/or diagnostic applications.

Claims

1. A method of reducing light attenuation within biological media, comprising:

delivering an effective amount of biocompatible fluid within said biological media to;

soak said biological media with said biocompatible fluid;

replace intercellular fluid within said biological media with said biocompatible fluid; and

reduce light reflection and refraction among intercellular and intracellular components within said biological media to enhance light transmission through said media.

2. The method of claim 1, wherein said biological media comprises a turbid media.

3. The method of claim 2, wherein said biological media comprises one or more of the group consisting of skin, dermis, mucous membranes, neural tissue, muscle, connective tissues, respiratory tissue, reproductive tissues, excretory tissues and digestive tissues.

4. The method of claim 3, wherein said biological media comprises skin.

5. The method of claim 1, wherein density of said biological media is increased.

6. The method of claim 1, wherein water content of said biological media is decreased.

7. The method of claim 1, wherein the index of refraction of said biological media is increased.

8. The method of claim 1, wherein said biocompatible fluid comprises glycerol.

9. The method of claim 1, wherein said biocompatible fluid comprises a dextrose solution.

10. The method of claim 1, wherein said biocompatible fluid has a lower absorption coefficient than water.

11. The method of claim 10, wherein said biocompatible fluid comprises perfluorocarbon.

12. The method of claim 1, wherein said light reflection and refraction is reduced by about one order of magnitude for visible wavelengths of light.

13. The method of claim 1, wherein said reduction of light reflection and refraction is reversible.

14. A method of reducing light scattering within biological tissue, said method comprising:

delivering a first biocompatible fluid within said biological tissue;

soaking said biological tissue with said first biocompatible fluid;

replacing intercellular fluid of said biological tissue with said first biocompatible fluid; and

reducing light scattering within said biological tissue by causing the ratio of refractive index of cellular components within the tissue to the refractive index of intercellular fluids to be closer to one than a native state.

15. The method of claim 14, wherein said cellular components include cellular fluids.

16. The method of claim 14, wherein said biological tissue comprises a turbid media.

17. The method of claim 14, wherein said biological tissue comprises skin.

18. The method of claim 14, wherein said biocompatible fluid is replaced by a second biocompatible fluid.

19. The method of claim 18, wherein said replacement with the second biocompatible fluid is such that the ratio of refractive index of cellular components within the tissue to the refractive index of intercellular fluids returns to the native state.

20. The method of claim 19, wherein said second biocompatible fluid comprises saline.

21. The method of claim 14, wherein said delivery comprises injection.

22. The method of claim 21, wherein said injection is by a hypodermic needle or a high velocity jet.

23. The method of claim 14, wherein said delivery comprises topical application preceded by removal of at least a portion of epidermis by ablation, chemical peel or mechanical debridement.

24. A method of reducing light attenuation within biological media, said method comprising:

providing a replacement fluid having a lower absorption coefficient than water at one or more water absorption peaks; and

delivering an effective amount of said replacement fluid within said biological media to;

soak said biological media with said replacement fluid;

replace intercellular fluid within said biological media with said replacement fluid; and

reduce light absorption within said biological media.