Method and Device for Optical Imaging of a Turbid Medium

• US 20080300472A1
• Filed: 11/17/2006
• Published: 12/04/2008
• Est. Priority Date: 11/23/2005
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Bakker, Levinus Pieter, Van Beek, Michael Cornelis, Van Der Mark, Martinus Bernardus
• Granted Patent: US 9,398,877 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 5/0091 for mammography
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/4312 Breast evaluation or disorder diagnosis A61B5/0091 takes precedence

Abstract

Disclosed is a method and a device for optical imaging of a turbid medium. This method comprises a reference measurement of reference intensities of light emanating from the turbid medium at a reference blood oxygen saturation (SaO2) in the turbid medium and a reference imaging step for reconstructing a reference image of the turbid medium from the measured reference intensities. Furthermore the method comprises a contrast measurement of the contrast intensity of the light emanating from the turbid medium at a contrast blood oxygen saturation (SaO2) level in the turbid medium and a contrast imaging step for reconstructing a contrast image of the turbid medium from the measured contrast intensities. A comparison is made between the contrast image to the reference image of the turbid medium.

Claims

1. A method for optical imaging of a turbid medium, which method comprises—

a reference measurement of reference intensities of light emanating from the turbid medium at a reference blood oxygen saturation (SaO2) in the turbid medium, —

and a reference imaging step for reconstructing a reference image of the turbid medium from the measured reference intensities, and wherein further

a contrast measurement of the contrast intensity of the light emanating from the turbid medium at a contrast blood oxygen saturation (SaO2) in the turbid medium,

and a contrast imaging step for reconstructing a contrast image of the turbid medium from the measured contrast intensities, and

a comparison is made between the contrast image to the reference image of the turbid medium.

3. A method for optical imaging of a turbid medium as claimed in claim 1, wherein

several contrast measurements are made to measure respective sets of reference light intensities emanating from the turbid medium at the contrast blood oxygen saturation level

several reference images and several contrast images are reconstructed from the sets of reference light intensities and from the sets of contrast light intensities, respectively and

the comparison is made of the several contrast images to the several reference images.

4. A method as claimed in claim 3, wherein

an average reference image is formed by averaging of the several reference images,

an average contrast image is formed by averaging of the several contrast images and

the comparison is made between the average contrast reference image and the average reference image.

5. A method of optical imaging of a turbid medium as claimed in claim 1, wherein the comparison involves subtraction or taking the ratio of the (average) contrast image and the average) reference image.

6. A method of optical imaging of a turbid medium as claimed in claim 1, wherein the blood oxygen saturation level in the turbid medium is modulated by modulating the ratio of the partial oxygen pressure (pO₂) to the partial nitrogen pressure (pN₂) administered to the subject to be examined.

7. A method according to claim 1, characterized in that the blood oxygen saturation level in the turbid medium is modulated by administering the subject to be examined O₂/N₂ in a ratio that is higher or lower than 0.26.

8. A method according to claim 3, characterized in that the O₂/N₂ ratio is administered via a gas mask.

2. A method for optical imaging of a turbid medium wherein the turbid medium is irradiated by light from a light source to generate the reference intensities and/or the contrast intensities of the light emanating from the turbid medium.

9. An apparatus for optical imaging of a turbid medium comprising

one or more detector modules to detect light emanating from the turbid medium at a reference and a contrast partial oxygen pressure, respectively

a reconstructor to receive output reference and contrast intensity signals from the detector module(s) to reconstruct reference and contrast images from the reference and contrast output intensity signals, respectively and

a comparator module to carry-out a comparison between the contrast and reference images.

10. A computer programme comprising instructions to

apply reference and contrast partial oxygen pressure to a turbid medium, in particular by controlling the partial oxygen pressure relative to the partial nitrogen pressure

compare contrast and reference images representing the turbid medium at the reference and contrast partial oxygen pressures, respectively.