DETERMINATION OF A LIPID WATER RATIO

• US 20130026367A1
• Filed: 04/18/2011
• Published: 01/31/2013
• Est. Priority Date: 04/21/2010
• 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: Hendriks, Bernardus Hendrikus Wilhelmus, Horikx, Jeroen Jan Lambertus, Lucassen, Gerhardus Wilhelmus, Nachabe, Rami, Van Der Voort, Marjolein
• Granted Patent: US 9,468,379 B2
• Time in Patent Office: Days
• US Class Current: 250/339.12
• 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 5/4869 Determining body composition
• CPC Class Codes: G01N 21/359 using near infrared light

Abstract

The present invention relates to an apparatus, a method and a computer program for determining a lipid-water ratio and a scattering parameter of a sample. In particular, the invention relates to an apparatus comprising a light source and a detector arranged to measure an optical parameter at various wavelengths, where the wavelengths are selected so that at two of the wavelengths the absorption coefficients for both water and lipids are substantially identical. This enables determination of a scattering parameter. A further measurement at a third wavelength enables determination of a water-lipid ratio. According to a specific embodiment, the light source and the detector are arranged in relation to an interventional device, so as to be able to examine a tissue in terms of lipid-water ratio and scattering during an intervention.

Claims

1. An apparatus (100) for determining a lipid-water ratio in an associated sample, comprising

a light source (S), and

a light detector (PD),

the light source (S) and the light detector (PD) being arranged to measure an optical parameter of the sample at a limited number of selected and distinct wavelengths, and arranged to measure a first, second and third optical parameter at the selected and distinct wavelengths lambda_1, lambda_2 and lambda_3, respectively,

wherein an optical absorption coefficient for water at lambda_1 is substantially similar to an optical absorption coefficient for water at lambda_2 and an optical absorption coefficient for lipids at lambda_1 is substantially similar to an optical absorption coefficient for lipids at lambda_2, and

wherein the apparatus is capable of determining a lipid-water ratio of the sample based on the first and second optical parameters measured at lambda_1 and lambda_2 and the third optical parameter measured at lambda_3.

2. An apparatus (100) according to claim 1, wherein the first selected wavelength lambda_1 and the second selected wavelength lambda_2 are chosen so as to enable disentangling of the contributions to the optical parameter from scattering and absorption.

3. An apparatus (100) according to claim 1, wherein the apparatus (100) is further capable of determining a scattering parameter (sp) via a direct relation between the scattering parameter (sp) and the first and second optical parameters.

4. An apparatus (100) according to claim 3, wherein the apparatus is further capable of determining a parameter indicative of freshness based on the scattering parameter (sp).

5. An apparatus (100) according to claim 1, wherein the apparatus (100) further comprises a plurality of light sources (S) with different wavelength bands and/or a plurality of light detectors (PD) with different wavelength bands, wherein two of the wavelength bands correspond to lambda_1 and lambda_2.

6. An apparatus (100) according to claim 1, wherein the apparatus (100) further comprises a processor (108) arranged for

receiving information (101) derived from the first optical parameter measured at lambda_1,

receiving information (102) derived from the second optical parameter measured at lambda_2,

receiving information (103) derived from the third optical parameter measured at lambda_3,

calculating a scattering parameter (sp) based on the information (101) derived from the first optical parameter and the information (102) derived from the second optical parameter, and

calculating a lipid-water ratio (lw) based on information derived from the scattering parameter (sp) and information (103) derived from the third optical parameter.

7. An apparatus (100) according to claim 6, wherein the apparatus (100) is further arranged to access a database comprising information regarding various tissue types, and identify which tissue type or tissue types the sample is most likely to comprise, and wherein the identification is based on the lipid-water ratio.

8. An apparatus (100) according to claim 1, wherein the wavelengths lambda_1 and lambda_2 are chosen to be substantially identical to any one of the sets of wavelengths {740.0 nm;

773.0 nm}, {955.0 nm;

1000.0 nm}, {1010.0 nm;

1128.5 nm}, {1150.5 nm;

1251.0 nm}, or {1380.9 nm;

1663.9 nm}.

9. An apparatus (100) according to claim 1, wherein the light source and the light detector are arranged in relation to an interventional device, so as to be able to determine a lipid-water ratio of a sample in the vicinity of the interventional device.

10. An apparatus (100) according to claim 1, wherein the apparatus is arranged for measuring an optical parameter at four different wavelengths including lambda_1, lambda_2 and lambda_3.

15. A system for determining a lipid-water ratio in an associated sample, comprising an apparatus according to claim 1, the system further comprising a database comprising information regarding a lipid-water ratio of the sample.

11. A method for determining a lipid-water ratio in a sample, the method comprising the steps of

measuring (S1) a first optical parameter at a first selected and distinct wavelength lambda_1,

measuring (S2) a second optical parameter at a second selected and distinct wavelength lambda_2,

measuring (S3) a third optical parameter at a third selected and distinct wavelength lambda_3, and

determining (S4) a scattering parameter based on the first optical parameter and the second optical parameter, and

determining (S5) a lipid-water ratio based on the scattering parameter and the third optical parameter

wherein an optical absorption coefficient for water at lambda_1 is substantially similar to an optical absorption coefficient for water at lambda_2 and an optical absorption coefficient for lipids at lambda_1 is substantially similar to an optical absorption coefficient for lipids at lambda_2.

12. A method according to claim 11, the method further comprising the step of measuring a fourth optical parameter at a fourth selected and distinct wavelength lambda_4, the fourth optical parameter also being used in the step of determining a lipid-water ratio, wherein the third wavelength lambda_3 has substantially the same absorption coefficient for water as the absorption coefficient for water at lambda_1 and lambda_2, and the absorption coefficient for lipids at lambda_4 is substantially the same as the absorption coefficient for lipids at lambda_1 and lambda_2.

13. A method according to claims 11, wherein the lipid-water ratio (lw) is determined using any one of the steps of:

inserting measured optical parameters into a look-up table,

measuring further optical parameters and fitting a model to a number of the measured optical parameters, wherein the model includes the lipid-water ratio as an input parameter,

comparing a number of the measured optical parameters with an analytical approximation based on diffusion theory, and/or

comparing a number of the measured optical parameters with the result of a Monte Carlo calculation.

14. A computer program product being adapted to enable a computer system comprising at least one computer having data storage means associated therewith to operate a processor arranged for

receiving information (101) derived from a first optical parameter measured at a first selected and distinct wavelength lambda_1,

receiving information (102) derived from a second optical parameter measured at a second selected and distinct wavelength lambda_2,

receiving information (103) derived from a third optical parameter measured at a third selected and distinct wavelength lambda_3,

calculating a scattering parameter (sp) based on the information (101) derived from the first optical parameter and the information (102) derived from the second optical parameter, and

calculating a lipid-water ratio (lw) based on information (sp) derived from the scattering parameter and information (103) derived from the third optical parameter, wherein an optical absorption coefficient for water at lambda_1 is substantially similar to an optical absorption coefficient for water at lambda_2 and an optical absorption coefficient for lipids at lambda_1 is substantially similar to an optical absorption coefficient for lipids at lambda_2.