Optical techniques for examination of biological tissue

• US 20040073101A1
• Filed: 03/31/2003
• Published: 04/15/2004
• Est. Priority Date: 12/02/1994
• Status: Active Grant

• Current Assignee: Britton Chance
• Original Assignee: Britton Chance
• Inventors: Chance, Britton
• Granted Patent: US 7,139,603 B2
• Time in Patent Office: Days
• US Class Current: 600/322
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/0242 for varying or adjusting the optical path length in the tissue
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 5/0073 by tomography, i.e. reconstruction of 3D images from 2D projections A61B5/0066 takes precedence
• CPC Class Codes: A61B 5/0091 for mammography
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: A61B 5/4312 Breast evaluation or disorder diagnosis A61B5/0091 takes precedence
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: G01N 2021/1789 Time resolved
• CPC Class Codes: G01N 2021/3181 using LEDs
• CPC Class Codes: G01N 2021/6421 Measuring at two or more wavelengths
• CPC Class Codes: G01N 2021/6484 Optical fibres
• CPC Class Codes: G01N 21/3151 using two sources of radiation of different wavelengths G01N21/33 - G01N21/39 take precedence
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B
• CPC Class Codes: G01N 21/6456 Spatial resolved fluorescence measurements; Imaging
• CPC Class Codes: G01N 2201/0696 Pulsed

Abstract

Methods and systems are described that examine tissue positioned between input ports and a detection port. At lease one source of a visible or infrared wavelength is provided that introduces electromagnetic radiation into the subject. The detection port is optically coupled to a detector that is connected to a detector circuit. Radiation intensities are selected for introduction at the input ports to define a null plane in the tissue. The detection port is positioned relative to the null plane. Radiation is introduced into the subject at the first input port and the radiation that migrates through the tissue is detected. The detector circuit stores a first detector signal corresponding to the first detected radiation. Radiation is introduced at the second input port and is detected. The first detector signal is subtracted from a second detector signal corresponding to the second detected radiation to obtain processed data.

Claims

1. A spectroscopic method of deriving data signals useful for examination of biological tissue of a subject, comprising the steps of:

providing at least one source of electromagnetic radiation of a visible or infrared wavelength selected to be scattered and absorbed while migrating in the tissue, said source being optically coupled to at least two input ports, and providing a detection port optically coupled to a detector, said detector connected to a detector circuit;

positioning a first input port and a second input port relative to selected input locations of a subject;

selecting for each input port first and second radiation intensities to be introduced to the tissue, said selected radiation intensities defining a null plane in the tissue;

positioning said detection port relative to a selected detection location of the examined tissue corresponding to said null plane, said input locations and detection location defining a volume of the examined tissue of the subject;

introducing into the tissue, at said first input port, radiation of said first intensity;

detecting, at said detection port, said first radiation that has migrated in the examined tissue;

storing, in said detector circuit, a first detector signal corresponding to said first detected radiation;

introducing into the tissue, at said second input port, radiation of said second intensity;

detecting, at said detection port, said second radiation that has migrated in the examined tissue;

storing, in said detector circuit, a second detector signal corresponding to said second detected radiation; and

subtracting said first detector signal from said second detector signal to obtain processed data corresponding to properties of said tissue volume.

3. The spectroscopic method of claim 1 or 2 wherein said first detector signal and said second detector signal are stored and subtracted in an analog form by said detection circuit.

4. The spectroscopic method of claim 1 or 2 further comprising, before said storing steps, converting said first and second detection signals to a digital form, said subtracting step being performed digitally on said first detector signal and said second detector signal in an digital circuit.

5. The spectroscopic method according to any preceding claim wherein said steps of positioning said input and detection port at the respective selected locations include placing said ports on the surface of the examined tissue.

6. The spectroscopic method of claim 1 or 2 wherein said steps of positioning said input and detection ports include orienting said ports relative to said input and detection locations.

7. The spectroscopic method of claim 5 wherein said orienting said input ports include directing an optical element of said port to said location.

8. The spectroscopic method according to any preceding claim wherein said positioning steps are performed in a manner that sweeps said null plane and said detector over at least a portion of said volume of the examined tissue.

9. The spectroscopic method of claim 1 wherein said step of selecting said first and second radiation intensities is performed in a manner that sweeps said null plane over at least a portion of said volume of the examined tissue and said method further comprising, simultaneously with said sweeping, positioning said detection port to detection locations corresponding to said swept null plane.

11. The spectroscopic method according to any preceding claim further comprising locating, in said tissue volume, a tissue region exhibiting different scattering or absorptive properties than the rest of the examined tissue volume.

12. The spectroscopic method of claim 11 further comprising imaging the examined tissue including said tissue region of different scattering or absorptive properties.

13. The spectroscopic method of claim 1 or 2 further comprising displaying an image of the examined tissue by utilizing to said processed data and relative locations of said input ports and said output ports.

14. The spectroscopic method according to any preceding claim further comprising a step of introducing an exogenous pigment into the tissue, said selected wavelength being sensitive to said pigment.

15. The spectroscopic method of claim 14 wherein said exogenous pigment is preferentially accumulated in a tissue region exhibiting different scattering or absorptive properties.

16. The spectroscopic method of claim 14 wherein said exogenous pigment is a fluorescing pigment when irradiated by a selected wavelength, and said detecting steps detecting preferentially radiation wavelength of said fluorescing pigment.

2. A spectroscopic method of deriving data signals useful for examination of biological tissue of a subject, comprising the steps of:

providing a source of electromagnetic radiation of a visible or infrared wavelength selected to be scattered and absorbed while migrating in the tissue, said source being optically coupled to an input port, and providing at least two detection ports optically coupled to at least one detector, said detector connected to a detector circuit;

positioning said input port relative to selected input locations of the tissue;

positioning a first detection port and a first detection port relative to selected detection locations of the examined tissue, said locations defining a null plane in the tissue a volume of the examined tissue of the subject;

introducing into the tissue, at said input port, radiation of a selected intensity;

detecting, at said first detection port, radiation that has migrated in the examined tissue and storing, in said detector circuit, a first detector signal corresponding to said detected radiation;

detecting, at said second detection port, radiation that has migrated in the examined tissue and storing, in said detector circuit, a second detector signal corresponding to said detected radiation; and

subtracting said first detector signal from said second detector signal to obtain processed data corresponding to properties of said tissue volume.

10. The spectroscopic method of claim 2 wherein said detecting steps are performed in a manner that changes the relative sensitivity of detection at said first and second detection port in order to sweep said null plane over at least a portion of said volume of the examined tissue and said method further comprising, simultaneously with said sweeping, positioning said input port to input locations corresponding to said swept null plane.

17. A spectroscopic system for examination of biological tissue of a subject, comprising:

at least one light source of electromagnetic radiation of a visible or infrared wavelength;

at least two input ports, optically coupled to said light source, constructed to introduce at selected input locations of the examined tissue said radiation of known intensities that define a null plane in the tissue;

a detection port located at a selected detection location of the examined tissue relative to said null plane;

a detector, optically coupled to said detection port, constructed to detect radiation that has migrated in the examined tissue;

a detector circuit connected to and receiving detection signal from said detector, said detector circuit including a sample-and-hold circuit and a subtraction circuit;

said detector circuit constructed to correlate emission of said radiation from a first input port with detection of radiation scattered and absorbed while migrating in the tissue, said detected radiation being stored as a first detection signal;

said detector circuit further constructed to correlate emission of said radiation from a second input port with detection of radiation scattered and absorbed while migrating in the tissue, said detected radiation being stored as a second detection signal;

said subtraction circuit constructed to subtract said detection signals; and

a processor, connected to and receiving said processed data from said subtraction circuit, constructed to evaluate the examined tissue.

19. A spectroscopic system of claim 17 further comprising intensity control means constructed to regulate intensities of radiation emitted from said first and second input ports.

20. A spectroscopic system of claim 19 wherein said intensity control means is further constructed to regulate said intensities in a manner that sweeps said null plane over at least a portion of said volume of the examined tissue.

21. A spectroscopic system of claim 19 or 20 further comprising positioning means constructed to displace said detection port to detection locations corresponding to said null plane.

22. A spectroscopic system of claim 17, 19, 20 or 21 further comprising positioning means constructed to displace said input ports to selected locations.

18. A spectroscopic system for examination of biological tissue of a subject, comprising:

a source of electromagnetic radiation of a visible or infrared wavelength;

an input port, optically coupled to said light source, constructed to introduce at a selected input location of the examined tissue said radiation;

a detector optically coupled to at least two detection ports located at selected detection locations defining a null plane in the examined tissue, said detector constructed to detect radiation that has migrated in the examined tissue to said detection ports;

a detector circuit connected to and receiving detection signal from said detector, said detector circuit including a sample-and-hold circuit and a subtraction circuit;

said detector circuit constructed to correlate emission of said radiation from said input port with detection of radiation scattered and absorbed while migrating in the tissue at said first detection port, said detected radiation being stored as a first detection signal;

said detector circuit further constructed to correlate emission of said radiation from said input port with detection of radiation scattered and absorbed while migrating in the tissue at said second detection port, said detected radiation being stored as a second detection signal;

said subtraction circuit constructed to subtract said detection signals; and

a processor, connected to and receiving said processed data from said subtraction circuit, constructed to evaluate the examined tissue.

23. A spectroscopic system of claim 18 further comprising detector controller means constructed to changes the relative sensitivity of detection at said first and second detection port in order to sweep said null plane over at least a portion of said volume of the examined tissue.

24. A spectroscopic system of claim 18 or 23 further comprising positioning means constructed to displace said input port to a selected location.

25. A spectroscopic system according to any preceding system claim wherein said input or detection ports are arranged in a linear array.

26. A spectroscopic system according to any preceding system claim wherein said input or detection ports are arranged a two dimensional array.

27. A spectroscopic system according to any preceding system claim wherein said subtraction circuit further includes an analog to digital converter, connected to said sample-and-hold circuit, constructed to digitize said first and second detection signals to produce digital detection signals, said subtraction circuit subtracting said digital detection signals to obtain said processed data.

28. A spectroscopic system according to any preceding system claim further comprising

an image processor connected to receive said processed data from said processor and create image data;

and

a display, connected to said image processor, constructed to display said image data representing the examined tissue.

29. A spectroscopic system according to any preceding system claim wherein said processor further constructed to locate, in said tissue volume, a tissue region exhibiting different scattering or absorptive properties than the rest of the examined tissue volume.

30. A spectroscopic system of claim 29 wherein said image processor is further constructed to create image data of said located tissue region exhibiting different scattering or absorptive properties;

and

said display constructed to display said image data.

31. A spectroscopic system according to any preceding system claim wherein said wavelength is sensitive to an endogenous pigment of the examined tissue.

32. A spectroscopic system according to any preceding system claim wherein said wavelength is sensitive to an exogenous pigment of the examined tissue.