Methods and systems for laser speckle imaging of tissue using a color image sensor

• US 10,169,862 B2
• Filed: 05/06/2016
• Issued: 01/01/2019
• Est. Priority Date: 05/07/2015
• Status: Active Grant

• Current Assignee: Stryker Corporation
• Original Assignee: Novadaq Technologies ULC (Stryker Corporation)
• Inventors: Andre, Marc, Bailey, Arthur E., Westwick, Paul Roald
• Primary Examiner(s): Chang, Jon
• Application Number:
  US15/148,959
• Publication Number:
  US 20160328848A1
• Time in Patent Office: 970 Days
• 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 5/0062 Arrangements for scanning
• 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 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/445 Evaluating skin irritation or skin trauma, e.g. rash, eczema, wound, bed sore
• CPC Class Codes: G01N 2021/479 Speckle
• CPC Class Codes: G06T 2207/10004 Still image; Photographic image
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/30104 Vascular flow; Blood flow; Perfusion
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/90 Determination of colour characteristics
• CPC Class Codes: H04N 1/482 using the same detector device sequentially for different colour components
• CPC Class Codes: H04N 1/603 controlled by characteristics of the picture signal generator or the picture reproducer
• CPC Class Codes: H04N 1/6086 by scene illuminant, i.e. conditions at the time of picture capture, e.g. flash, optical filter used, evening, cloud, daylight, artificial lighting, white point measurement, colour temperature

Abstract

Methods and systems for imaging tissue of a subject are disclosed, and involve illuminating the tissue with a coherent light having a coherent wavelength, acquiring image data of the tissue using a color image sensor, and processing the image data using laser speckle contrast analysis while correcting for differences in sensitivity of color pixels at the coherent wavelength to generate a perfusion image of the tissue. The perfusion image is then displayed to the user. Also disclosed are methods and systems for correcting for ambient light and for acquiring white light images along with laser speckle images.

Claims

1. A method for imaging tissue of a subject, the method comprising:

illuminating the tissue with a coherent light having a coherent wavelength;

acquiring image data of the tissue using a color image sensor, said color image sensor having pixels, some of the pixels corresponding to a first color, some of the pixels corresponding to a second color, and some of the pixels corresponding to a third color; and

processing the image data using laser speckle contrast analysis while correcting for differences in sensitivity of color pixels at the coherent wavelength to generate a perfusion image of the tissue wherein the correction includes applying a first correction factor to the first color pixels, a second correction factor to the second color pixels and a third correction factor to the third color pixels.

2. The method of claim 1 wherein the correction factors are determined during image data acquisition.

3. The method of claim 1 further comprising alternating the coherent light between a turned on state and a turned off state during image data acquisition.

4. The method of claim 3 wherein the image data acquired during the turned off state of the coherent light comprises white light image data to generate a white light image.

5. The method of claim 1 further comprising displaying the perfusion image.

6. The method of claim 1 wherein the coherent wavelength ranges from about 750 nm to about 850 nm.

7. A method for imaging tissue of a subject, the method comprising:

illuminating the tissue with a coherent light having a coherent wavelength;

acquiring image data of the tissue using a color image sensor; and

processing the image data using laser speckle contrast analysis while correcting for differences in sensitivity of different color pixels at the coherent wavelength to generate a perfusion image of the tissue wherein correcting for difference in sensitivity of color pixels at the coherent wavelength comprises changing color channel dependent analog or digital gain of the image sensor.

8. A method for imaging tissue of a subject, the method comprising:

illuminating the tissue with a coherent light having a coherent wavelength;

acquiring image data of the tissue using a color image sensor; and

processing the image data using laser speckle contrast analysis while correcting for differences in sensitivity of color pixels at the coherent wavelength to generate a perfusion image of the tissue wherein correcting for differences in sensitivity of color pixels at the coherent wavelength comprises calculating separate speckle images based on each set of like color pixels, and combining the calculated speckle images to calculate the perfusion image.

9. A system for imaging tissue of a subject, the system comprising:

a coherent light source to generate coherent light having a coherent wavelength;

a color image sensor to acquire image data of the tissue, said color image sensor having pixels, some of the pixels corresponding to a first color, some of the pixels corresponding to a second color, and some of the pixels corresponding to a third color; and

a processor to process the image data using laser speckle contrast analysis while correcting for differences in sensitivity of color pixels at the coherent wavelength to generate a perfusion image of the tissue wherein the correction includes applying a first correction factor to the first color pixels, a second correction factor to the second color pixels and a third correction factor to the third color pixels.

10. The system of claim 9 wherein the correction factors are determined during manufacturing of the system, calibration of the system, use of the system, or a combination thereof.

11. The system of claim 9 further comprising a control unit in communication with the color image sensor, the processor, or a combination thereof to control the color image sensor, the processor, the coherent light source, or a combination thereof.

12. The system of claim 9 further comprising means to alternate the coherent light between a turned on state and a turned off state during image data acquisition.

13. The system of claim 12 wherein the image data acquired during the turned off state of the coherent light comprises white light image data to generate a white light image.

14. The system of claim 13 wherein the image data comprises ambient light image data, and the processor further generates an ambient light image.

15. The system of claim 13 further comprising a display to display the perfusion image and the white light image.

16. The system of claim 9 wherein the coherent wavelength ranges from about 750 nm to about 850 nm.

17. The system of claim 9 further comprising a display to display the perfusion image.

18. A system for imaging tissue of a subject, the system comprising:

a coherent light source to generate coherent light having a coherent wavelength;

a color image sensor to acquire image data of the tissue; and

a processor to process the image data using laser speckle contrast analysis while correcting for differences in sensitivity of color pixels at the coherent wavelength to generate a perfusion image of the tissue wherein correcting for difference in sensitivity of color pixels at the coherent wavelength comprises changing color channel dependent analog or digital gain of the image sensor.

19. A system for imaging tissue of a subject, the system comprising:

a coherent light source to generate coherent light having a coherent wavelength;

a color image sensor to acquire image data of the tissue; and

a processor to process the image data using laser speckle contrast analysis while correcting for differences in sensitivity of color pixels at the coherent wavelength to generate a perfusion image of the tissue wherein the correction for differences in sensitivity of color pixels at the coherent wavelength comprises a calculation of separate speckle images based on each set of like color pixels, and combining the calculated speckle images to calculate the perfusion image.