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US 7,532,919 B2Granted
Measuring tissue oxygenation
AssigneeUniversity of Massachusetts
InventorsOlusola O. Soyemi, Babs R. Soller, Ye Yang
Life of this patent
Estimating the term…
Abstract
Methods and systems for calculating tissue oxygenation, e.g., oxygen saturation, in a target tissue are disclosed. In some embodiments, the methods include: (a) directing incident radiation to a target tissue and determining reflectance spectra of the target tissue by measuring intensities of reflected radiation from the target tissue at a plurality of radiation wavelengths; (b) correcting the measured intensities of the reflectance spectra to reduce contributions thereto from skin and fat layers through which the incident radiation propagates; (c) determining oxygen saturation in the target tissue based on the corrected reflectance spectra; and (d) outputting the determined value of oxygen saturation.
Claims37
A method for calculating oxygen saturation in a target tissue, the method comprising:
- directing incident radiation from a source to a target tissue and determining reflectance spectra of the target tissue with a detector by measuring intensities of reflected radiation from the target tissue at a plurality of radiation wavelengths;
- correcting the measured intensities of the reflectance spectra to reduce contributions thereto from skin and fat layers through which the incident radiation propagates;
- determining oxygen saturation in the target tissue based on the corrected reflectance spectra;
- and
- outputting the determined value of oxygen saturation,
- wherein determining reflectance spectra of the target tissue comprises:
- measuring, at a first source-detector spacing, a first reflectance spectrum from the target tissue that comprises a first weighting of contributions from the target tissue and from the skin and fat layers, and measuring, at a second source-detector spacing different from the first source-detector spacing, a second reflectance spectrum from the target tissue that comprises a second weighting of contributions from the target tissue and from the skin and fat layers different from the first weighting;
- and
- wherein correcting the measured intensities of the reflectance spectra comprises:
- correcting the measured intensities of the first reflectance spectrum based on the measured intensities of the second reflectance spectrum.
7 more elements
A method of monitoring blood volume in a patient, the method comprising:
- directing incident radiation from a source to a target tissue of the patient and determining reflectance spectra of the target tissue with a detector by measuring intensities of reflected radiation from the target tissue at a plurality of wavelengths;
- correcting the measured intensities of the reflectance spectra to reduce contributions thereto from skin and fat layers through which the incident radiation propagates;
- determining total heme concentration in the target tissue based on the corrected reflectance spectra;
- assessing a blood volume in the patient based on the total heme concentration;
- and
- outputting the assessed blood volume,
- wherein determining reflectance spectra of the target tissue comprises:
- measuring, at a first source-detector spacing, a first reflectance spectrum from the target tissue that comprises a first weighting of contributions from the target tissue and from the skin and fat layers, and measuring, at a second source-detector spacing different from the first source-detector spacing, a second reflectance spectrum from the target tissue that comprises a second weighting of contributions from the target tissue and from the skin and fat layers different from the first weighting;
- and
- wherein correcting the measured intensities of the reflectance spectra comprises:
- correcting the measured intensities of the first reflectance spectrum based on the measured intensities of the second reflectance spectrum.
8 more elements
A method for calculating oxygen saturation in a target tissue, the method comprising:
- directing incident radiation from a source to a target tissue and determining reflectance spectra of the target tissue with a detector by measuring intensities of reflected radiation from the target tissue at a plurality of radiation wavelengths;
- determining light attenuation spectra of the target tissue from the reflectance spectra, and fitting the light attenuation spectra to a model light attenuation equation;
- determining oxygen saturation in the target tissue based on the fitting of the light attenuation spectra;
- and
- outputting the determined value of oxygen saturation,
- wherein fitting the light attenuation spectra to a model comprises performing a two-stage fitting procedure wherein, in a first stage, initial values of one or more model parameters are determined, and in a second stage, the light attenuation spectra are fitted to the model, wherein the model comprises the initial parameter values determined in the first stage;
- and
- wherein determining reflectance spectra of the target tissue comprises:
- measuring, at a first source-detector spacing, a first reflectance spectrum from the target tissue that comprises a first weighting of contributions from the target tissue and from skin and fat layers through which the incident radiation passes, and measuring, at a second source-detector spacing different from the first source-detector spacing, a second reflectance spectrum from the target tissue that comprises a second weighting of contributions from the target tissue and from the skin and fat layers different from the first weighting;
- and
- correcting the measured intensities of the first reflectance spectrum based on the measured intensities of the second reflectance spectrum.
8 more elements
A system, comprising:
- a light source configured to direct incident radiation to a target tissue;
- a detector;
- and
- a processor coupled to the detector and configured to:
- determine reflectance spectra of the target tissue;
- correct the reflectance spectra to reduce contributions thereto from skin and fat layers through which the incident radiation propagates;
- and
- determine oxygen saturation in the target tissue based on the corrected reflectance spectra,
- wherein the processor is configured to determine the reflectance spectra by:
- measuring, at a first source-detector spacing, a first reflectance spectrum from the target tissue that comprises a first weighting of contributions from the target tissue and from skin and fat layers through which the incident radiation passes, and measuring, at a second source-detector spacing different from the first source detector spacing, a second reflectance spectrum from the target tissue that comprises a second weighting of contributions from the target tissue and from the skin and fat layers different from the first weighting;
- and
- wherein the processor is configured to correct the reflectance spectra by:
- correcting the measured intensities of the first reflectance spectrum based on the measured intensities of the second reflectance spectrum.
10 more elements
Dependencies are inferred from the claim text.