Fluorescent diagnostic system and method providing color discrimination enhancement

• US 6,422,994 B1
• Filed: 09/15/1998
• Issued: 07/23/2002
• Est. Priority Date: 09/24/1997
• Status: Expired due to Fees

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Ueno, Hitoshi, Hirata, Tadashi, Kaneko, Mamoru, Doguchi, Nobuyuki, Tomioka, Makoto, Ozawa, Takeshi, Kawauchi, Masahiro, Uesugi, Takefumi, Takehana, Sakae, Hirao, Isami, Imaizumi, Katsuichi, Kogen, Yasukazu
• Primary Examiner(s): Leubecker, John P.
• Application Number:
  US09/153,793
• Time in Patent Office: 1,407 Days
• Field of Search: 600/109, 600/160, 600/476, 600/478, 250/461.2, 250/373, 250/372
• US Class Current: 600/160
• CPC Class Codes: A61B 1/00009 of image signals during a use of endoscope
• CPC Class Codes: A61B 1/0005 combining images e.g. side-by-side, superimposed or tiled
• CPC Class Codes: A61B 1/00186 with imaging filters
• CPC Class Codes: A61B 1/043 for fluorescence imaging
• CPC Class Codes: A61B 1/045 Control thereof
• CPC Class Codes: A61B 1/0638 providing two or more wavelengths
• CPC Class Codes: A61B 1/0646 with illumination filters
• CPC Class Codes: A61B 1/0655 Control therefor
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: H04N 23/555 for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes

Abstract

A fluorescent imaging device to prevent the breakdown of a fluorescent image high-sensitivity imaging apparatus has a light source for endoscope use which selectively switches between an excitation light and a white light. This introduces a light into a light guide of an endoscope and such light is emitted onto an object. A fluorescent image high-sensitivity imaging device images the fluorescences obtained by excitation with the excitation light which is emitted onto the object. A white light imaging device images a white light image obtained from the white light which is emitted onto the object. A switch inputs a power source onto the fluorescent image high-sensitivity imaging apparatus and there is a mechanism to prevent overprint on an image plane of the fluorescent image high-sensitivity imaging apparatus which is in the imaging condition with the power source inputted. A fluorescent observation image generating device generates a fluorescent observation image signal for fluorescent observation use, and outputted from the fluorescent image high-sensitivity imaging measure of the imaging part is in electric signal from; which a white light observation image signal used for white light observation is derived.

Claims

1. A fluorescent imaging system for use with an endoscope including a first light guide for illuminating tissue under examination and a second light guide for transmitting tissue image data resulting from such illumination, the imaging system comprising:

a light source for connection to the first light guide which generates excitation light at a frequency which will excite a fluorescent response from the tissue under examination;

a fluorescent imaging device for connection to the second light guide and responsive to image data provided thereby, the imaging device including;

an optical system which separates the image data into at least two color bands, and

electro-optical circuitry that generates electrical signals representative of the optical image data for each color band;

an image processing subsystem coupled to the imaging device including;

a conversion circuit operative to convert the electrical signals representative of the optical image data for each color band respectively into predetermined color image signals; and

a video signal generating circuit responsive to the color image signals to generate a first video signal which represents an enhanced image of fluorescence in the tissue under examination; and

a display device for displaying the fluorescence image;

an interpretation reference subsystem that generates a second video signal representing a tissue fluorescence image color interpretation guide related to the predetermined color image signals for display on the display device; and

a superimposing circuit that combines the first and second video signals to display the fluorescence image and the interpretation guide together on the display device.

2. A fluorescent imaging system according to claim 1, wherein:

the imaging device generates a first electrical signal representative of optical image data in a color band within a first portion of the spectrum, and a second electrical signal representative of optical image data in a color band within a second portion of the spectrum, and wherein

the image processing subsystem generates the first video signal as a function of the ratio of the first and second electrical signals.

3. A fluorescent imaging system according to claim 1, wherein:

the imaging subsystem generates a first electrical signal representative of optical image data in a color band within a first portion of the spectrum, and a second electrical signal representative of optical image data in a color band within a second portion of the spectrum, and wherein

the image processing subsystem generates the first video signal as a function of the difference between the first and second electrical signals.

4. A fluorescent imaging system according to claim 1, wherein the optical system comprises:

a beam splitter which provides a plurality of light beams; and

a plurality of optical filters, one filter being positioned in the path of each of the light beams and respectively corresponding to one of the color bands.

5. A fluorescent imaging system according to claim 4, wherein the beam splitter comprises at least one dichroic mirror.

6. A fluorescent imaging system according to claim 5, wherein the electro-optical circuitry comprises:

an imaging intensifier optically coupled to each of the filters, and a charge coupled device optically coupled to the output of each of the image intensifiers.

7. A fluorescent imaging system according to claim 1, wherein the electro-optical circuitry comprises:

a light amplifier in the path of each of the color bands; and

an opto-electric converter optically coupled to the output of each of the light amplifiers.

8. A fluorescent imaging system according to claim 7, where each of the light amplifiers is an image intensifier.

9. A fluorescent imaging system according to claim 7, wherein each of the opto-electric converters is a charge coupled device.

10. A fluorescent imaging system according to claim 1, wherein the image processing subsystem comprises:

an image processing circuit responsive to the image data electrical signals, and which generates a color separation video signal for each of the color bands; and

a video processor which combines the color separation video signals to generate the first video signal.

11. A fluorescent imaging system according to claim 10, wherein:

the electro-optical circuitry in the imaging device includes a plurality of light amplification devices, one of the light amplification devices being provided for each of the image data color bands; and

wherein

the image processing subsystem further comprises;

a computation circuit responsive to the color separation video signals to determine the relative amplification of each of the light amplification devices; and

a control circuit connected to the computation circuit, the control circuit and the computation circuit being operative together to adjust the relative amplification of the light amplification devices in accordance with a predetermined computational routine.

12. A fluorescent imaging system according to claim 11, wherein the control circuit is responsive to an external command to initiate the predetermined computational routine;

and wherein

the predetermined computational routine sets the relative amplification to a predetermined initial value, and then recursively determines the ratio of the maximum values of the color separation video signals, compares the ratio with upper and lower reference values, adjusts the relative amplification upward by a predetermined amount if the ratio is less than the lower reference value, and adjusts the relative amplification downward by the predetermined amount if the ratio is greater than the upper reference value, and again determines the ratio of the maximum values of the color separation video signals, the routine being repeated until the ratio falls between the upper and lower reference values.

13. A fluorescent imaging system as described in claim 1, in which the interpretation reference subsystem generates a color discrimination scale as the second video signal, and in which the superimposing circuit combines the first and second video signals to display the fluorescence image and the color discrimination scale as the fluorescence image interpretation reference together on the display device.

14. A fluorescent imaging system according to claim 13, further including:

a manual input device for positioning the color discrimination scale at any desired location relative to the tissue fluorescence image on the display device.

15. A fluorescent imaging system according to claim 1, further including:

a manual input device for positioning the image interpretation guide at any desired location relative to the tissue fluorescence image on the display device.

16. A fluorescent imaging system according to claim 1, wherein the interpretation reference subsystem comprises:

a color reference generator that generates a plurality of color reference signals, each representing one of the image data color bands; and

a video circuit responsive to the color reference signals to generate a color discrimination scale as the second video signal.

17. A fluorescent imaging system according to claim 16, wherein the color discrimination scale is in the form of the plurality of stacked color bars, each bar corresponding to one of the colors represented by the color discrimination signals.

18. A fluorescent imaging system according to claim 17, wherein the colors represented by the color discrimination signals are cyan, white, bright red and dark red.

19. A fluorescent imaging system according to claim 17, further comprising:

a manual input device for positioning the color discrimination scale at any desired location relative to the tissue fluorescence image on the display device.

20. A fluorescent imaging system according to claim 16, wherein the second circuit includes:

a separate circuit path for each of the different colors, each circuit path including a plurality of variable gain devices, one of which is connected to a different one of the reference signal sources; and

a combining circuit connected to the output of each of the variable gain circuits to generate one of the color discrimination signals, the gain of each of the variable gain circuits being adjusted so that the output of the combining circuit represents the desired color.

21. A fluorescent imaging system according to claim 20, wherein:

the reference signals represent a red color band, and a green color band; and

wherein the color discrimination signals represent cyan, white, bright red and dark red color bars in the color discrimination scale.

22. A fluorescent imaging system according to claim 1, in which the light source is selectively operable to generate white light and excitation light;

and further including;

a further imaging device coupled to the second light guide including a first electro-optical subsystem which generates an electrical signal representing a white-light image of the tissue under examination resulting from exposure to white light;

a further image processing subsystem coupled to the further imaging device that converts the white light image electrical signal into a white-light video signal; and

a switching device which selectively connects the first or the second video signal to the display device.

23. A fluorescent imaging system according to claim 22, further including a protective device that prevents damage to the fluorescent imaging device due to impingement of a white-light image thereon.

24. A fluorescent imaging system according to claim 23, wherein the protective device is operative to prevent impingement of a white light image on the fluorescent imaging device.

25. A fluorescent imaging system according to claim 23, wherein the protective device is operative to reduce the sensitivity of the fluorescent imaging device when excitation light is not being generated.

26. A fluorescent imaging system according to claim 23, further including an optical path switching device which blocks the passage of light to the fluorescent imaging device when the light source is not emitting excitation light.

27. A fluorescent imaging system according to claim 23, wherein the protective device prevents the light source from generating white light when the fluorescent imaging device is activated.

28. A fluorescent imaging system according to claim 23, wherein the protective device is operative to shut down the fluorescent imaging device when excitation light is not being generated.

29. A fluorescent imaging system according to claim 22, in which the interpretation reference subsystem generates a color discrimination scale as the second video signal, and in which the superimposing circuit combines the first and second video signals to display the fluorescence image and the color discrimination scale as the fluorescence image interpretation reference together on the display device.

30. A fluorescent imaging system according to claim 29, further including a manual input device connected to the superimposing circuit which is operative to position the color discrimination scale at any desired location relative to the tissue fluorescence image on the display device.

31. A fluorescent imaging system according to claim 29, wherein the color discrimination scale is in the form of a plurality of stacked bars, each bar being of a different color.

32. A fluorescent imaging system according to claim 23, wherein the light source is comprised of:

a first illumination device for selectively generating the white light or the excitation light;

a second illumination device;

a light detector coupled to a first illumination device;

a switching device for selectively activating the first or the second illumination device; and

a control circuit for the switching device responsive to the output of the light detector to deactivate the first illumination device and to activate the second illumination device when abnormalities are detected in the light output of the first illumination device.

33. An imaging system according to claim 32, wherein the second illumination device is a light emitting diode which emits light at the wave length of the excitation light.

34. A fluorescent imaging method for identifying abnormal tissue the method comprising the steps of:

illuminating the tissue under examination with excitation light at a frequency which will excite a fluorescent response;

collecting optical image data representing the fluorescent response;

separating the collected optical image data into at least two color bands;

generating electrical signals representative of the optical image data for each color band;

converting the electrical signals representative of the optical image data for each color band into predetermined color image signals;

forming a first video signal from the predetermined color image signals which represents an enhanced image of fluorescence excited in the tissue under examination;

displaying the first video signal on a display device;

generating a visual tissue fluorescence image color interpretation guide related to the predetermined color image signals; and

displaying the fluorescence image and the fluorescence image interpretation guide together on the display device.

35. A fluorescent imaging method as described in claim 34, in which the color interpretation guide is a color discrimination scale in the form of a plurality of stacked color bars, each bar being of a predetermined color.

36. A fluorescent imaging method according to claim 35, wherein the step of generating the color discrimination scale comprises:

generating a plurality of reference signals, each signal representing one of the color bands;

generating a plurality of color bar signals, each signal representing one of the color bars, from the reference signals; and

generating a second video display signal from the plurality of color bar signals which represents an image of the plurality of stacked color bars.

37. A fluorescent imaging method according to claim 36, wherein each of the color bar signals is generated by combining the reference signals after adjusting the amplitudes thereof to values which will yield a video display of the required color.

38. A fluorescent imaging method according to claim 35, wherein the step of generating the color discrimination scale comprises:

generating a first reference signal which represents a red color band;

generating a second reference signal which represents a green color band;

generating cyan, white, bright red and dark red color bar signals, from the reference signals; and

generating a second video display signal from the cyan, white, bright red and dark red color bar signals.

39. A fluorescent imaging method according to claim 35, further comprising the step of moving the color discrimination scale to a location on the display device in close proximity to a selected portion of the tissue fluorescence image display.

40. A fluorescent imaging method according to claim 35, further comprising the step increasing the number of color bars in the color discrimination scale on the display device while displaying tissue fluorescence image.

41. A fluorescent imaging method according to claim 34, further comprising the step of moving the image interpretation reference to a location on the display device in close proximity to a selected portion of the tissue fluorescence image display.

42. A fluorescent imaging method according to claim 34, in which the image interpretation reference is in the form of a color discrimination scale;

and further including the step of displaying the enhanced fluorescence image and the color discrimination scale together on the display device.

43. A fluorescent imaging method according to claim 42, wherein the step of generating the image interpretation reference comprises:

generating a plurality of reference signals, each signal representing each of the color bands;

generating a plurality of color discrimination signals, each signal representing a predetermined index color, from the reference signals; and

generating a second video display signal from the plurality of color discrimination signals which represents an image of the plurality of index colors displayed adjacent to each other.

44. A fluorescent imaging method according to claim 43, wherein each of the color discrimination signals is generated by combining the reference signals after adjusting the amplitudes thereof to values which will yield a video display of the required index color.

45. A fluorescent imaging method according to claim 44, wherein the index colors are cyan, white, bright red and dark red.

46. An imaging method according to claim 42, wherein the step of preventing damage to the opto-electric devices comprises preventing impingement of white light thereon.

47. A fluorescent imaging method according to claim 42, wherein the step of preventing damage to the opto-electric devices comprises reducing the sensitivity thereof when excitation light is not being generated.

48. An imaging method according to claim 42, wherein a primary illumination source selectively provides white light or excitation light and a secondary illumination source provides only excitation light, and wherein the step of preventing damage to the opto-electric devices comprises deactivating the primary illumination source in case of abnormalities in the light output thereof, and thereafter activating the secondary illumination source, and maintaining the opto-electrical devices in a disabled condition until the secondary illumination source is activated.

49. A fluorescent imaging method according to claim 34, further including:

selectively illuminating the tissue under examination with white light or excitation light;

creating an image of the tissue under examination resulting from exposure to the white light;

generating an electrical signal representing a white light image;

processing the white light image electrical signal to generate a second video signal;

selectively displaying the first or the second video signal on a display device; and

preventing damage to the opto-electric devices which generate the fluorescence image electrical signals due to impingement of a white light image thereon.

50. A fluorescent imaging method according to claim 49, further including the steps of generating a third video signal for displaying a color discrimination scale on the display device, and superimposing the second and third video signals for simultaneous display on the display device.

51. A fluorescent imaging method according to claim 50, further comprising the step of manually adjusting the third video signal to position the color discrimination scale at a desired location relative to the tissue fluorescence image on the display device.

52. A fluorescent imaging method according to claim 50, wherein the color discrimination scale is displayed in the form of a plurality of stacked color bars, each bar being of a different color.

53. A fluorescent imaging system according to claim 52, wherein the color bars are cyan, white, bright red and dark red.

54. A fluorescent imaging method according to claim 50, further including the step of increasing the number of colors in the color bar display while displaying the fluorescent image on the display device.

55. A fluorescent imaging method according to claim 49, wherein the step of generating the second video signal comprises combining the fluorescent image electrical signals as a function of the ratio of the first and second image data signals.

56. A fluorescent imaging method according to claim 49, wherein the step of generating the fluorescent image electrical signals comprises:

generating a first image signal representative of image data in a color band within a first portion of the spectrum; and

generating a second image signal representative of image data in a color band within a second portion of the spectrum, and wherein

the step of generating the second video signal comprises generating a signal as a function of the difference between the first and second image data signals.

57. A fluorescent imaging method according to claim 49, wherein the step of separating the fluorescent image into color bands comprises:

splitting the optical image data a plurality of light beams; and

filtering each of the light beams with a filter corresponding to one of the color bands.

58. A fluorescent imaging method according to claim 57, wherein the step of generating the image data electrical signals further comprises:

amplifying each of the optical image data color bands; and

converting each of the amplified color bands into an electrical signal.

59. A fluorescent imaging method according to claim 49, wherein:

the image data electrical signals are generated by separate electro-optical devices which convert the optical image for each color band into electrical signals; and

wherein

the step of forming the second video signal further comprises;

separately enhancing the electro-optically generated signals for each color band in accordance with predetermined characteristics of the separate electro-optical devices; and

combining the separately enhanced electrical signals.

60. A fluorescent imaging method according to claim 49, wherein:

the step of generating the fluorescent image electrical signals further comprises separately amplifying the optical image data for each color band; and

thereafter converting the amplified optical image data to an electrical signal.

61. A fluorescent imaging method according to claim 60, wherein:

the step of generating the first video signal further comprises;

adjusting the relative amplification of the optical image data in accordance with a predetermined computational routine.

62. A fluorescent imaging method according to claim 34, wherein the step of generating the image data electrical signals comprises:

generating a first image data signal representative of image data in a color band within a first portion of the spectrum; and

generating a second image data signal representative of image data in a color band within a second portion of the spectrum, and wherein

the step of combining the separate image data signals comprises generating a signal as a function of the ratio of the first and second image data signals.

63. A fluorescent imaging method according to claim 34, wherein the step of generating the image data electrical signals comprises:

generating a first image data signal representative of image data in a color band within a first portion of the spectrum; and

generating a second image data signal representative of image data in a color band within a second portion of the spectrum, and wherein

the step of combining the separate image data signals comprises generating a signal as a function of the difference between the first and second image data signals.

64. A fluorescent imaging method according to claim 34, wherein the step of separating the collected optical image data into color bands comprises:

splitting the optical image data a plurality of light beams; and

filtering each of the light beams with a filter corresponding to one of the color bands.

65. A fluorescent imaging method according to claim 64, wherein the step of generating the image data electrical signals comprises:

amplifying each of the optical image data color bands; and

converting each of the amplified color bands into an electrical signal.

66. A fluorescent imaging method according to claim 34, wherein:

the image data electrical signals are generated by separate electro-optical devices which convert the optical image data for each color band into electrical signals; and

wherein

the step of forming the first video signal comprises;

separately enhancing the electro-optically generated signals for each color band in accordance with predetermined characteristics of the separate electro-optical devices; and

combining the separately enhanced electrical signals.

67. A fluorescent imaging method according to claim 66, wherein:

the step of generating the image data electrical signals further comprises separately amplifying the optical image data for each color band; and

thereafter converting the amplified optical image data to an electrical signal.

68. A fluorescent imaging method according to claim 67, wherein the step of generating the first video signal further comprises adjusting the relative amplification of the optical image data in accordance with a predetermined computational routine.

69. A fluorescent imaging method according to claim 68, further including the step of initiating the predetermined computational routine with an external command;

and wherein the predetermined computational routine comprises;

setting the relative amplification to a predetermined initial value, and then recursively

determining the ratio of the maximum values of the color separation video signals,

comparing the ratio with upper and lower reference values,

adjusting the relative amplification upward by a predetermined amount if the ratio is less than the lower reference value,

adjusting the relative amplification downward by the predetermined amount if the ratio is greater than the upper reference value, and

again determining the ratio of the maximum values of the color separation video signals, the routine being repeated until the ratio falls between the upper and lower reference values.