Electronic endoscope system, processor for electronic endoscope, and method of displaying vascular information

• US 20110077462A1
• Filed: 09/15/2010
• Published: 03/31/2011
• Est. Priority Date: 09/30/2009
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Saitou, Takaaki, Minetoma, Yasuhiro, Chun, Minkyung
• Granted Patent: US 8,668,636 B2
• Time in Patent Office: Days
• US Class Current: 600/109
• CPC Class Codes: A61B 1/000094 extracting biological structures
• CPC Class Codes: A61B 1/00186 with imaging filters
• CPC Class Codes: A61B 1/063 for monochromatic or narrow-band illumination
• CPC Class Codes: A61B 1/0638 providing two or more wavelengths
• CPC Class Codes: A61B 1/0646 with illumination filters
• CPC Class Codes: A61B 1/0653 with wavelength conversion
• CPC Class Codes: A61B 1/0655 Control therefor
• 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 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/489 Blood vessels

Abstract

Illumination light projected into a body cavity includes first to third narrowband rays of different wavelength ranges, at least one of these narrowband rays has a central wavelength of not more than 450 nm. Under these narrowband rays, first to third narrowband image signals are respectively obtained through an endoscope. Based on the first to third narrowband image signals, vascular areas containing blood vessels are determined, and a first luminance ratio between the first and third narrowband signals and a second luminance ratio between the second and third narrowband signals are calculated at every pixel of the vascular areas. From the calculated first and second luminance ratios, information about both the depth and oxygen saturation of the blood vessels is acquired with reference to correlation data that correlates the first and second luminance ratios to the vessel depth and the oxygen saturation.

Claims

1. An electronic endoscope system comprising:

an illuminating device for projecting illumination light toward subject tissues inside a body cavity that include blood vessels, wherein said illumination light includes first and second narrowband rays of different wavelength ranges from each other, at least one of the first and second narrowband rays having a central wavelength of not more than 450 nm, or said illumination light has a wavelength range including both of the wavelength ranges of the first and second narrowband rays;

an electronic endoscope having an imaging device for capturing and outputting image signals that represent luminance of said illumination light as being projected toward and then reflected from said subject tissues;

a first narrowband signal obtaining device for obtaining first and second narrowband signals from said image signals, the first and second narrowband signals corresponding to the first and second narrowband rays respectively; and

a vascular information acquiring device for acquiring vascular information about the blood vessels on the basis of the first and second narrowband signals, said vascular information including both information about vessel depth and information about oxygen saturation representative of the percentage of oxygenated hemoglobin in the blood vessels.

2. The electronic endoscope system as claimed in claim 1, wherein the first and second narrowband rays include such wavelengths, at which light absorbance in oxygenated hemoglobin differs from light absorbance in reduced hemoglobin that is not combined with oxygen, and that the light absorbance in hemoglobin to the first narrowband ray and the light absorbance in hemoglobin to the second narrowband ray differ from each other.

3. The electronic endoscope system as claimed in claim 2, further comprising:

a second narrowband signal obtaining device for obtaining a third narrowband signal from said imaging signals, the third narrowband signal corresponding to a third narrowband ray having a different wavelength range from the first and second narrowband rays;

a luminance ratio calculator for calculating a first luminance ratio between the first and third narrowband signals and a second luminance ratio between the second and third narrowband signals; and

a first storage device previously storing correlations between the first and second luminance ratios and the vessel depth and the oxygen saturation, wherein

said vascular information acquiring device acquires the information about the vessel depth and the information about the oxygen saturation from the first and second luminance ratios calculated by said luminance ratio calculator, with reference to said correlation stored in the first storage device.

4. The electronic endoscope system as claimed in claim 3, wherein the first storage device stores said correlation by correlating a luminance coordinate system that indicates the first and second luminance ratios to a vascular information coordinate system that indicates the vessel depth and the oxygen saturation;

said vascular information acquiring device determines first coordinates in said luminance coordinate system, corresponding to the first and second luminance ratios calculated by said luminance ratio calculator, and then determines second coordinates in said vascular information coordinate system, corresponding to the first coordinates of said luminance coordinate system, one coordinate value of the second coordinates representing the vessel depth and the other coordinate value of the second coordinates representing the oxygen saturation.

5. The electronic endoscope system as claimed in claim 3, wherein the first narrowband ray has a wavelength range of 440±

10 nm, the second narrowband ray has a wavelength range of 470±

10 nm, and the third narrowband ray has a wavelength range of 400±

10 nm.

6. The electronic endoscope system as claimed in claim 3, wherein said imaging device has red pixels, green pixels and blue pixels, which are provided with red, green and blue filters respectively, and

said illuminating device is capable of projecting white broadband light having a wavelength range covering red, green and blue regions, to which the red, green and blue pixels are respectively sensitive, wherein

said electronic endoscope system further comprises an ordinary image producer for producing an ordinary image from said image signal as captured while the broadband light is being projected.

7. The electronic endoscope system as claimed in claim 6, wherein two of the first to third narrowband rays have wavelength ranges, to which either the blue pixel or the green pixel is sensitive, whereas a remaining one of the first to third narrowband rays has a wavelength range, to which both the blue pixel and the green pixel are sensitive.

8. The electronic endoscope system as claimed in claim 3, wherein said illuminating device is capable of projecting the first to third narrowband rays individually, and wherein said narrowband signal obtaining device obtains the first to third narrowband signals respectively from three frames of said image signals, which are captured respectively under the first to third narrowband rays which are sequentially projected from said illuminating device.

9. The electronic endoscope system as claimed in claim 7, wherein said illuminating device is capable of projecting the first to third narrowband rays individually, and wherein said narrowband signal obtaining device obtains the first to third narrowband signal from first and second frames of said image signals, the first frame being captured while said illuminating device is projecting one of the first to third narrowband rays that has a wavelength range, to which either the blue pixel or the green pixel is sensitive, the second frame being captured while said illuminating device is projecting other two of the first to third narrowband rays simultaneously.

10. The electronic endoscope system as claimed in claim 7, further comprising a second storage device storing correlation between luminance values of blue and green pixels contained in a frame of said image signals, which is captured under the broadband light, wherein

said illuminating device is capable of projecting the broadband light and at least one of the first to third narrowband rays simultaneously;

said imaging device captures a first frame while said illuminating device is projecting one of the first to third narrowband rays that has a wavelength range, to which either the blue pixel or the green pixel is sensitive, simultaneously with the broadband light, and said imaging device captures a second frame while said illuminating device is projecting other two of the first to third narrowband rays simultaneously with the broadband light; and

said narrowband signal obtaining device obtains the first to third narrowband signals by subtracting those luminance values which are based on the broadband light from respective luminance values of the first and second frames, with reference to the correlation stored in the second storage device.

11. The electronic endoscope system as claimed in claim 3, wherein said illuminating device is capable of projecting white broadband light having a wavelength range covering from blue region to red region as well as all the wavelength ranges of the first to third narrowband rays, and

wherein said electronic endoscope system further comprises an optical filter for filtering the broadband light as reflected from the subject tissues, said optical filter being able to selectively pass one of the first to third narrowband rays therethrough to said imaging device, so said imaging device sequentially outputs image signals each corresponding to the one of the first to third narrowband rays that passes through said optical filter, and said narrowband signal obtaining device obtains these image signals as the first to third narrowband signals.

12. The electronic endoscope system as claimed in claim 3, further comprising a third narrowband signal obtaining device for obtaining a fourth narrowband signal corresponding to a fourth narrowband ray that has a different wavelength range from the first to third narrowband rays, wherein said vascular information acquiring device acquires the vascular information including information about both the vessel depth and the oxygen saturation on the basis of the first to fourth narrowband signals.

13. The electronic endoscope system as claimed in claim 1, further comprising a display device for displaying the information on the vessel depth and the information on the oxygen saturation selectively from one another or simultaneously with each other.

14. A processor for an electronic endoscope that projects illumination light toward subject tissues inside a body cavity and outputs image signals representative of luminance of said illumination light as being reflected from the subject tissues and captured through an imaging device, wherein said illumination light includes first and second narrowband rays of different wavelength ranges from each other, at least one of the first and second narrowband rays having a central wavelength of not more than 450 nm, or said illumination light has a wavelength range including both of the wavelength ranges of the first and second narrowband rays, said processor comprising:

a signal receiving device for receiving said image signals from said electronic endoscope;

a narrowband signal obtaining device for obtaining first and second narrowband signals from said image signals, the first and second narrowband signals respectively corresponding to the first and second narrowband rays; and

a vascular information acquiring device for acquiring vascular information about the blood vessels on the basis of the first and second narrowband signals, said vascular information including both information about vessel depth and information about oxygen saturation representative of the percentage of oxygenated hemoglobin in the blood vessels.

15. The processor for the electronic endoscope as claimed in claim 14, wherein the first and second narrowband rays include such wavelengths, at which light absorbance in oxygenated hemoglobin differs from light absorbance in reduced hemoglobin that is not combined with oxygen, and that the light absorbance in hemoglobin to the first narrowband ray and the light absorbance in hemoglobin to the second narrowband ray differ from each other.

16. A method of acquiring vascular information, comprising the steps of:

projecting illumination light through an electronic endoscope toward subject tissues inside a body cavity, including blood vessels, wherein said illumination light includes first and second narrowband rays of different wavelength ranges from each other, at least one of the first and second narrowband rays having a central wavelength of not more than 450 nm, or said illumination light has a wavelength range including both of the wavelength ranges of the first and second narrowband rays;

capturing and outputting image signals through an imaging device, said imaging signal representing luminance of said illumination light as being reflected from said subject tissues;

obtaining first and second narrowband signals from said image signals, the first and second narrowband signals corresponding to the first and second narrowband rays respectively; and

acquiring vascular information about the blood vessels on the basis of the first and second narrowband signals, said vascular information including both information about vessel depth and information about oxygen saturation representative of the percentage of oxygenated hemoglobin in the blood vessels.

17. The method of acquiring vascular information as claimed in claim 16, wherein the first and second narrowband rays include such wavelengths, at which light absorbance in oxygenated hemoglobin differs from light absorbance in reduced hemoglobin that is not combined with oxygen, and that the light absorbance in hemoglobin to the first narrowband ray and the light absorbance in hemoglobin to the second narrowband ray differ from each other.