PERFUSION ASSESSMENT USING TRANSMISSION LASER SPECKLE IMAGING

• US 20130204112A1
• Filed: 02/07/2013
• Published: 08/08/2013
• Est. Priority Date: 02/07/2012
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Laser Associated Sciences, LLC (Medtronic Plc)
• Inventors: White, Sean Michael, Yang, Bruce Yee, Rice, Tyler Bywaters
• Granted Patent: US 9,848,787 B2
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/6826 Finger

Abstract

Methods and apparatus for measuring perfusion using transmission laser speckle imaging are provided. The apparatus comprises a coherent light source and a detector configured to measure transmitted light associated with an unfocused image at one or more locations. The coherent light source and detector are positioned in a transmission geometry. The apparatus further comprises means for securing the coherent light source and the detector to the tissue sample in a fixed transmission geometry relative to the tissue sample. The apparatus may further comprise at least one processor to receive information from the detector and process detected variations in transmitted light intensity to determine a single metric of perfusion. The method may comprise the steps transilluminating a tissue sample with coherent light, recording spatial and/or temporal variations in the transmitted light signal, determining speckle contrast value(s), and computing a metric of perfusion.

Claims

1. An apparatus for measuring tissue perfusion, comprising:

a coherent light source; and

a detector configured to receive one or more pixels associated with an unfocused image of a tissue sample,

wherein the coherent light source and the detector are positionable in a transmission geometry with respect to the tissue sample.

2. The apparatus of claim 1, further comprising an enclosure configured to accommodate the tissue sample, and wherein the enclosure is coupled to the coherent light source and the detector.

3. The apparatus of claim 2, wherein the enclosure comprises a clam shell configuration.

4. The apparatus of claim 1, wherein the tissue sample is a finger.

5. The apparatus of claim 1, wherein the tissue sample is toe, nostril, or earlobe.

6. The apparatus of claim 1, wherein the apparatus further comprises an opaque sheet positioned between the detector and the tissue sample, wherein the opaque sheet is configured to adjust an aperture of the detector.

7. The apparatus of claim 1, wherein the detector is a photodiode

8. An apparatus for measuring tissue perfusion, comprising:

a coherent light source;

a detector configured to receive one or more pixels associated with an image of a tissue sample; and

means for securing the coherent light source and the detector to the tissue sample in a fixed transmission geometry relative to the tissue sample, such that movement of the tissue sample while measuring tissue perfusion does not alter the transmission geometry.

9. The apparatus of claim 8, wherein a field of view of the tissue sample is configured to remain constant upon movement of the tissue sample.

10. The apparatus of claim 8, wherein the means for securing comprises an enclosure configured to securely accommodate the tissue sample, and wherein the enclosure is coupled to the coherent light source and the detector.

11. The apparatus of claim 10, wherein the enclosure comprises a clam shell configuration.

12. The apparatus of claim 8, wherein the tissue sample is a finger.

13. The apparatus of claim 8, wherein the tissue sample is toe, nostril, or earlobe.

14. The apparatus of claim 8, wherein the apparatus further comprises:

an opaque sheet positioned between the detector and the tissue sample, wherein the opaque sheet is configured to adjust an aperture of the detector.

15. A method of measuring perfusion in a region of tissue, comprising:

receiving, by a processor, a plurality of light intensity values from a detector, wherein the plurality of light intensity values is associated with transilluminating a tissue sample with a coherent light source rendering an unfocused image,

computing, by the processor, a speckle contrast parameter based at least in part on the plurality of light intensity values; and

determining, by the processor, a single metric of perfusion based at least in on the computed speckle contrast parameter.

16. The method of claim 15, further comprising:

displaying, by the processor, the determined single metric of perfusion.

17. The method of claim 15, wherein the plurality of light intensity values received by the detector is configured to remain constant upon movement of the tissue sample.

18. The method of claim 15, wherein the tissue sample is a finger

19. The method of claim 15, wherein the tissue sample is a toe, nostril, or earlobe.

20. The method of claim 15, wherein the computing step comprises computing a speckle contrast parameter based at least in part on all pixels from the unfocused image.