Detecting thermal discrepancies in vessel walls

• US 20030004430A1
• Filed: 08/16/2002
• Published: 01/02/2003
• Est. Priority Date: 09/20/1995
• Status: Active Grant

• 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: Bearman, Gregory H., Willerson, James T., Casscells, S. Ward, Eastwood, Michael L., Krabach, Timothy N.
• Granted Patent: US 6,993,382 B2
• Time in Patent Office: Days
• US Class Current: 600/545
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2017/22001 Angioplasty, e.g. PCTA
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• 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 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/015 By temperature mapping of body part
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/413 Monitoring transplanted tissue or organ, e.g. for possible rejection reactions after a transplant
• CPC Class Codes: A61B 5/6853 with a balloon

Abstract

An infrared, heat-sensing catheter particularly useful for identifying potentially fatal arterial plaques in patients with disease of the coronary or other arteries and its use are detailed. In one embodiment, an infrared fiberoptic system (with or without ultrasound) is employed at the tip of the catheter to locate inflamed, heat-producing, atherosclerotic plaque, which is at greater risk for rupture, fissure, or ulceration, and consequent thrombosis and occlusion of the artery. In another embodiment, a catheter with an infrared detector (with or without ultrasound) employed at its tip will likewise locate inflamed heat-producing atherosclerotic plaque. The devices and methods of the invention may be used to detect abscesses, infection, and cancerous regions by the heat such regions differentially display over the ambient temperature of immediately adjacent tissues. The methods and devices of the invention may also be used to detect regions of cooler than ambient tissue in a vessel or organ which indicate cell death, thrombosis, cell death, hemorrhage, calcium or cholesterol accumulations, or foreign materials.

Claims

1. An apparatus for analyzing optical radiation of a vessel, comprising:

at least one fiber capable of transmitting said radiation and capable of placement proximate to a locus of a wall of said vessel;

a balloon encasing a disks end of said fiber;

said balloon, transparent to said radiation or opaque to said radiation, and having a black inner surface; and

,

a detector capable of detecting a difference in said radiation between said locus and average optical radiation along said vessel wall.

2. The apparatus of claim 1, wherein said optical radiation is infra-red radiation.

3. The apparatus of claim 1, wherein said vessel is a blood vessel.

4. The apparatus of claim 1, further comprising at least two fibers.

5. The apparatus of claim 4, wherein at least one of said fibers is a reference fiber and another of said fibers is a signal fiber.

6. The apparatus of claim 5, wherein said distal end of said signal fiber is optically connected to an optically reflective surface capable of directing optical radiation arising radially to said distal end, into said fiber.

7. The apparatus of claim 5, wherein said reference fiber is coated on its distal end with a material that substantially prevents said optical radiation from entering said reference fiber.

8. The apparatus of claim 1, wherein said inner surface of said opaque balloon emits a black body spectrum.

9. The apparatus of claim 1, wherein said balloon, upon inflation, substantially limits flow of fluids within said vessel.

10. The apparatus of claim 1, wherein said balloon, upon inflation, substantially excludes said fluids between said fiber and said wall of said vessel most proximate to said locus.

11. The apparatus of claim 1, wherein said placement is alone an axis of said vessel.

12. The apparatus of claim 1, wherein said locus contains plaque.

13. The apparatus of claim 12, wherein said plaque is at risk of rupturing, or at risk of thrombosis due to the presence of inflammatory cells on or beneath the luminal surface of said plaque.

14. The apparatus of claim 1, wherein said wall is interior of said vessel.

15. The apparatus of claim 1, further comprising a catheter.

16. The apparatus of claim 1, further comprising a guidewire.

17. The apparatus of claim 1, wherein said detector is optically connected to a proximal end of said fiber, and if more than one fiber, to a proximal end of each of said fibers.

18. The apparatus of claim 5, wherein said detector further comprises a multi-wavelength radiometer.

19. The apparatus of claim 18, wherein said radiometer further comprises a spinning circular variable filter whose transmission wavelength is a function of its angle of rotation.

20. The apparatus of claim 19, wherein said filter is transparent to radiation with a wavelength of approximately between 2 to 14 micrometers.

21. The apparatus of claim 19, wherein said filter is transparent to radiation with a wavelength of approximately between 3 to 7micrometers.

22. The apparatus of claim 19, wherein said distal ends of said signal fiber and said reference fiber are offset from one another a distance sufficient to allow sampling of radiation emitted from either fiber to pass said filter at a substantially identical location on sod filter.

23. The apparatus of claim 18, wherein said radiometer is optically connected to at least one photoelectric device capable of converting said radiation into an electrical signal.

24. The apparatus of claim 23, wherein said photoelectric device is electrically connected to a device capable of digitizing said electrical signal.

25. The apparatus of claim 24, wherein said digitized signal is mathematically fitted to a curve selected from a spectrum of curves for black bodies held at temperatures between approximately 300-310°

K., said curves plotted as numbers of photons emitted from each of said black bodies for each of said wavelengths.

28. The method of claim 27, wherein said optical radiation is infra-red radiation.

29. The method of claim 27, wherein said vessel is a blood vessel.

30. The method of claim 27, further comprising placing at least two fibers proximate to said locus.

31. The method of claim 30, wherein at least one of said fibers is a reference fiber and another of said fibers is a signal fiber.

32. The method of claim 31, wherein said distal end of said signal fiber is optically connected to an optically reflective surface capable of directing optical radiation arising radially to said distal end, into said fiber.

33. The method of claim 32, wherein said reference fiber is coated on its distal end with a material that substantially prevents optical radiation from entering said reference fiber.

34. The method of claim 27, wherein said inner surface of said balloon emits a black body spectrum.

35. The method of claim 27, wherein said placement of said fiber is along an axis of said vessel.

36. The method of claim 27, wherein said locus contains plaque.

37. The method of claim 36, wherein said plaque is at risk of rupturing or thrombosis.

38. The method of claim 27, wherein said wall is interior of said vessel.

39. The method of claim 27, wherein said placement of said fiber and said balloon is accomplished by catheterization.

40. The method of claim 39, wherein said catheterization further comprises insertion of a guidewire.

41. The method of claim 27, wherein said detector is optically connected to a proximal end of said fiber, and if more than one fiber, to a proximal end of each of said fibers.

42. The method of claim 31, wherein said detection further comprises passing said radiation through a multi-wavelength radiometer.

43. The method of claim 42, wherein said passing of said radiation through said radiometer further comprises spinning a circular variable filter whose transmission wavelength is a function of its angle of rotation, and passing said radiation through said spinning filter.

44. The method of claim 43, wherein said filter is transparent to and is used to sample radiation with a wavelength of approximately between 2 to 14 micrometers.

45. The method of claim 43, wherein said filter is transparent to and is used to sample radiation with a wavelength of approximately between 3 to 7 micrometers.

46. The method of claim 43, wherein said filter is transparent to and is used to sample radiation with a wavelength of approximately 3 micrometers.

47. The method of claim 42, further comprising offsetting distal ends of said signal fiber and said reference fiber from one another a distance sufficient to allow said sampling of radiation emitted from either fiber to pass said filter at a substantially identical location on said filter.

48. The method of claim 42, wherein detection is further accomplished by optically connecting said radiometer to at least one photoelectric device, and converting said radiation into an electrical signal.

49. The method of claim 48, wherein said detection is further accomplished by digitizing said electrical signal.

50. The method of claim 48, wherein detection is further accomplished by mathematically fitting said digitized signal to a curve selected from a spectrum of curves for black bodies held at temperatures between approximately 300-310°

K., and plotting said curves as numbers of photons emitted from each of said black bodies for each of said wavelengths.

54. The use of the device of claim 1 in the method of claim 27.

55. The use of the device of claim 1 to detect inflammation in an organ, vessel, body cavity or opening.

56. The use of the device of claim 1 to detect the absence of living cells in an organ, vessel, body cavity or opening.

26. A catheter for analyzing infra-red radiation of a blood vessel, comprising:

at least two fibers capable of transmitting said radiation and capable of placement along an axis of said vessel proximate to a plaque-containing locus of an interior wall of said vessel;

wherein at least one of said fibers is a reference fiber coated on its distal end with a material that substantially prevents said optical radiation from entering said reference fiber; and

,

wherein at least one of the other of said fibers is a signal fiber whose distal end is optically connected to an optically reflective surface capable of directing optical radiation arising radially to said distal end of said signal fiber, into said signal fiber;

a balloon encasing said distal ends of each of said fibers, and which balloon upon inflation substantially limits the flow of fluids within said vessel, and which balloon substantially excludes said fluids between said fibers and said wall of said vessel most proximate to said locus;

said balloon, transparent to said radiation, or opaque to said radiation and having an inner surface exhibiting spatially constant optical radiation emissivity, wherein said inner surface of said opaque balloon emits a black body spectrum;

a guidewire; and

,

a detector, optically connected to a proximal end of each of said fibers, capable of detecting a difference in said radiation between said locus and average optical radiation along said wall;

said detector further comprising a multi-wavelength radiometer with a spinning circular variable filter, said filter being such that its transmission wavelength is a function of its angle of rotation and is transparent to radiation with a wavelength of approximately 3 micrometers;

said distal ends of said fibers being offset from one another a distance sufficient allow sampling if radiation emitted from either fiber to pass said filter at a substantially identical position on said filter;

said radiometer optically connected to at least one photoelectric device capable of converting said radiation into an electrical signal, which signal is capable of being digitized, and which digitized signal is mathematically fitted to a curve selected from a spectrum of curves for black bodies held at temperatures between approximately 300-310°

K., said curves plotted as numbers of photons emitted from each of said black bodies for each of said wavelengths.

27. A method for analyzing optical radiation of a locus in a vessel wall, comprising:

placing at least one optical fiber, capable of transmitting said radiation, proximate to said locus;

inflating a balloon encasing a distal end of said fiber within said vessel to cause said balloon to limit flow of fluids within said vessel, said balloon being transparent to said radiation, or opaque to said radiation and having an inner surface exhibiting spatially constant optical radiation emissivity; and

, transmitting said radiation along said fiber to a detector capable of detecting a difference in said radiation between said locus and average optical radiation along said vessel wall.

51. A method of detecting plaque at risk of rupturing along a blood vessel, comprising:

inserting a guidewire into said vessel;

catheterizing said vessel along said guidewire with at least two fibers capable of transmitting infra-red radiation along an axis of said vessel proximate to a plaque-containing locus of an interior wall of said vessel;

wherein at least one of said fibers is a reference fiber coated on its distal end with a material that substantially prevents said optical radiation from entering said reference fiber; and

,

wherein at least one of the other of said fibers is a signal fiber whose distal end is optically connected to an optically reflective surface capable of directing optical radiation arising radially to said distal end of said signal fiber, into said signal fiber;

inflating a balloon encasing said distal ends of each of said fibers, and which balloon upon inflation substantially limits the flow of fluids within said vessel, and which balloon substantially excludes said fluids between said fibers and said wall of said vessel most proximate to said locus;

said balloon, transparent to said infra-red radiation, or opaque-to said infra-red radiation and having an inner surface exhibiting spatially constant optical radiation emissivity, wherein said inner surface of said opaque balloon emits a black body spectrum;

transmitting said infra-red radiation to a detector, optically connected to a proximal end of each of said fibers, capable of detecting a difference in said radiation between said locus and average optical radiation along said wall;

said detector further comprising a multi-wavelength radiometer with a spinning circular variable filter, said filter being such that its transmission wavelength is a function of its angle of rotation and is transparent to radiation with a wavelength of approximately 3 micrometers;

said distal ends of said fibers being offset from one another a distance sufficient to allow sampling of radiation emitted from either fiber to pass said filter at a substantially identical position on said filter;

said radiometer optically connected to at least one photoelectric device capable of converting said radiation into an electrical signal, which signal is capable of being digitized, and which digitized signal is mathematically fitted to a curve selected from a spectrum of curves for black bodies held at temperatures between approximately 300-310 °

K., said curves plotted as numbers of photons emitted from each of said black bodies for each of said wavelengths; and

,

determining if said plaque has a temperature elevated above that of said average vessel wall temperature.

53. The method of claim 51, wherein said determination step is accomplished by analyzing optical radiation of said plaque locus in said vessel wall, comprising:

placing at least one fiber, capable of transmitting said radiation, proximate to said locus;

inflating a balloon encasing a distal end of said fiber within said vessel to cause said balloon to limit flow of fluids within said vessel, said balloon being transparent to said radiation, or opaque to said radiation and having an inner surface exhibiting spatially constant optical radiation emissivity; and

,

transmitting said radiation along said fiber to a detector capable of detecting a difference in said radiation between said locus and average optical radiation along said vessel wall.

52. A method of surgically treating a patient with a plurality of plaque loci within a vessel of said patient, comprising:

determining which one or more of said plurality of plaque loci has a temperature elevated above that of the average vessel wall temperature; and

,

removing or reducing plaque loci found to have said elevated temperature.