Method and apparatus for the non-invasive measurement of tissue function and metabolism by determination of steady-state fluorescence anisotropy

• US 10,194,804 B2
• Filed: 06/22/2018
• Issued: 02/05/2019
• Est. Priority Date: 04/13/2006
• Status: Active Grant

• Current Assignee: Cellview Imaging Inc.
• Original Assignee: Cellview Imaging Inc.
• Inventors: Zuckerman, Ralph
• Primary Examiner(s): Nagpaul, Jyoti
• Application Number:
  US16/015,659
• Publication Number:
  US 20180360318A1
• Time in Patent Office: 228 Days
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/14555 specially adapted for the eye fundus
• CPC Class Codes: A61B 5/14556 by fluorescence A61B5/14555 takes precedence
• CPC Class Codes: A61B 5/4842 Monitoring progression or stage of a disease
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: G01N 2021/6484 Optical fibres
• CPC Class Codes: G01N 21/6445 Measuring fluorescence polarisation
• CPC Class Codes: G01N 21/645 Specially adapted constructive features of fluorimeters
• CPC Class Codes: G01N 2201/0683 Brewster plate; polarisation controlling elements
• CPC Class Codes: G01N 2201/12 Circuits of general importance; Signal processing

Abstract

A non-invasive measurement of biological tissue reveals information about the function of that tissue. Polarized light is directed onto the tissue, stimulating the emission of fluorescence, due to one or more endogenous fluorophors in the tissue. Fluorescence anisotropy is then calculated. Such measurements of fluorescence anisotropy are then used to assess the functional status of the tissue, and to identify the existence and severity of disease states. Such assessment can be made by comparing a fluorescence anisotropy profile with a known profile of a control.

Claims

1. An apparatus for non-invasively evaluating tissue comprising:

a stimulator configured to apply a stimulation to a tissue in a resting state in order to cause the tissue to transition to a stimulated state;

an illuminator configured to irradiate the tissue in the resting and stimulated states with light in order to cause at least one endogenous fluorophor in the tissue to fluoresce;

a detector configured to detect fluorescence emitted by the at least one fluorophor in the tissue in the resting and stimulated states; and

a processor configured to;

determine a resting steady-state fluorescence anisotropy of the fluorescence emitted by the at least fluorophor in the tissue in the resting state;

determine a stimulated steady-state fluorescence anisotropy of the fluorescence emitted by the at least fluorophor in the tissue in the stimulated state;

construct a resting fluorescence anisotropy map of a region of the tissue based on the resting steady-state fluorescence anisotropy;

construct a stimulated fluorescence anisotropy map of the region of the tissue based on the stimulated steady-state fluorescence anisotropy;

subtract the resting fluorescence anisotropy map from the stimulated fluorescence anisotropy map; and

identify a tissue dysfunction based on a result of the subtraction.

2. The apparatus of claim 1, wherein metabolism of the tissue in the stimulated state is increased when compared to metabolism of the tissue in the resting state.

3. The apparatus of claim 1, wherein the result of the subtraction is indicative of a tissue metabolism level, and wherein the processor is configured to identify the tissue dysfunction based on a comparison of the result of the subtraction with a threshold associated with a metabolism level in non-diseased tissue.

4. The apparatus of claim 3, wherein the processor is configured to identify the tissue dysfunction in response to a determination that the result of the subtraction is below the threshold.

5. The apparatus of claim 1, wherein the processor is configured to subtract the resting fluorescence anisotropy map from the stimulated fluorescence anisotropy map point by point or pixel by pixel.

6. The apparatus of claim 1, wherein the illuminator is configured to irradiate the tissue with polarized light.

7. The apparatus of claim 6, wherein the detector comprises a polarizer configured to separate the light emitted by the tissue into polarized components parallel and perpendicular to a plane of the polarized light.

8. The apparatus of claim 1, wherein the at least one fluorophor comprises lipoamide dehydrogenase (LipDH).

9. The apparatus of claim 1, wherein the processor is configured to:

determine the resting steady-state fluorescence anisotropy within a latency period of a metabolic response of the tissue to the stimulation; and

determine the stimulated steady-state fluorescence anisotropy outside of the latency period of the metabolic response of the tissue to the stimulation.

10. The apparatus of claim 1, wherein the stimulation comprises at least one of light or supplemental oxygen.

11. The apparatus of claim 1, wherein the tissue dysfunction comprises at least one of presence or severity of a disease, and wherein the disease comprises at least one of cancer, optic neuropathy, neurodegenerative disease, or mitochondrial disease.

12. The apparatus of claim 1, wherein the tissue comprises at least one of skin tissue, cervix tissue, abdominal tissue, esophagus tissue, stomach tissue, gut tissue, lung tissue, or ocular tissue.

13. The apparatus of claim 1, wherein:

the tissue comprises at least one another endogenous fluorophor different from the at least one fluorophor;

the illuminator is further configured to cause the at least one another fluorophor to fluoresce; and

the at least one of the detector or processor is further configured to filter fluorescence emitted by the at least one fluorophor and at least one another fluorophor to isolate the fluorescence emitted by the at least one fluorophor.

14. A method for non-invasively evaluating tissue comprising:

causing a tissue to transition from a resting state to a stimulated state by applying stimulation to the tissue;

irradiating the tissue in the resting and stimulated states with light in order to cause a first endogenous fluorophor in the tissue to fluoresce;

detecting fluorescence emitted by the first fluorophor in the tissue in the resting and stimulated states; and

by a processor;

determining a resting steady-state fluorescence anisotropy of the fluorescence emitted by the first fluorophor in the tissue in the resting state;

determining a stimulated steady-state fluorescence anisotropy of the fluorescence emitted by the first fluorophor in the tissue in the stimulated state;

constructing a resting fluorescence anisotropy map of a region of the tissue based on the resting steady-state fluorescence anisotropy;

constructing a stimulated fluorescence anisotropy map of the region of the tissue based on the stimulated steady-state fluorescence anisotropy; and

identifying a tissue dysfunction based on subtracting the resting fluorescence anisotropy map from the stimulated fluorescence anisotropy map.

15. The method of claim 14, wherein:

a result of the subtraction is indicative of a tissue metabolism level; and

the method further comprises, by the processor;

identifying the tissue dysfunction based on determining that the result of the subtraction is below a threshold associated with a metabolism level in non-diseased tissue.

16. The method of claim 14, further comprising, by the processor, subtracting the resting fluorescence anisotropy map from the stimulated fluorescence anisotropy map point by point or pixel by pixel.

17. The method of claim 14, wherein:

the irradiating comprises irradiating the tissue with polarized light; and

the detecting comprises separating the light emitted by the tissue into polarized components parallel and perpendicular to a plane of the polarized light.

18. The method of claim 14, wherein the first fluorophor comprises lipoamide dehydrogenase (LipDH).

19. The method of claim 14, wherein the tissue comprises a second endogenous fluorophor different from the first fluorophor, the irradiating further comprises causing the second fluorophor to fluoresce, and the method further comprises:

isolating the fluorescence emitted by the first fluorophor by filtering fluorescence emitted by the first and second fluorophors.

20. The method of claim 14, further comprising, by the processor:

determining the resting steady-state fluorescence anisotropy within a latency period of a metabolic response of the tissue to the stimulation; and

determining the stimulated steady-state fluorescence anisotropy outside of the latency period of the metabolic response of the tissue to the stimulation.

21. The method of claim 14, wherein the stimulation comprises at least one of light or supplemental oxygen.

22. The method of claim 14, wherein the tissue dysfunction comprises at least one of presence or severity of a disease, and wherein the disease comprises at least one of cancer, optic neuropathy, neurodegenerative disease, or mitochondrial disease.