Abstract:
Methods and apparatuses for the determination of an attribute of the tissue of an individual use non-invasive Raman spectroscopy. For example, the alcohol concentration in the blood or tissue of an individual can be determined non-invasively. A portion of the tissue is illuminated with light, the light propagates into the tissue where it is Raman scattered within the tissue. The Raman scattered light is then detected and can be combined with a model relating Raman spectra to alcohol concentration in order to determine the alcohol concentration in the blood or tissue of the individual. Correction techniques can be used to reduce determination errors due to detection of light other than that from Raman scattering from the alcohol in the tissue. Other biologic information can be used in combination with the Raman spectral properties to aid in the determination of alcohol concentration, for example age of the individual, height of the individual, weight of the individual, medical history of the individual and his/her family, ethnicity, skin melanin content, or a combination thereof. The method and apparatus can be highly optimized to provide reproducible and, preferably, uniform radiance of the tissue, low tissue sampling error, depth targeting of the tissue layers or sample locations that contain the attribute of interest, efficient collection of Raman spectra from the tissue, high optical throughput, high photometric accuracy, large dynamic range, excellent thermal stability, effective calibration maintenance, effective calibration transfer, built-in quality control, and ease-of-use.
Abstract:
A method of determining a measure of a tissue state (e.g., glycation end-product or disease state) in an individual is disclosed. A portion of the skin of the individual is illuminated with excitation light, then light emitted by the tissue due to fluorescence of a chemical with the tissue responsive to the excitation light is detected. The detected light can be combined with a model relating fluorescence with a measure of tissue state to determine a tissue state. The invention can illuminate the skin and detect responsive light over a time that spans a plurality of cardiac cycles of the individual, which can, as an example, help mitigate the effects of time-varying signals such as those due to hemoglobin. The invention can also determine the amount of light to be directed to the skin, for example by controlling the time that a light source is energized. The amount of illumination light can be determined from a skin reflectance characteristic such as pigmentation or melanin in the skin. Controlling the amount of light directed to the tissue can reduce the dynamic range required of a corresponding optical system, for example by allowing a single system to accurately measure individuals with very light skin and individuals with very dark skin.
Abstract:
Coronary artery calcification (CAC) occurs at an earlier age in diabetes and is a risk factor for coronary artery disease (CAD) in subjects with or without diabetes. One postulated mechanism for the increased CAC is the accelerated accumulation of advanced glycation end products (AGEs) in the vasculature. As certain collagen AGEs fluoresce, skin intrinsic fluorescence (SIF) can act as a novel maker of collagen AGEs levels. The present invention provides methods and apparatuses for detecting SIF that can be a useful marker of CAD risk and a therapeutic target.
Abstract:
A method of determining a measure of a tissue state (e.g., glycation end-product or disease state) in an individual. A portion of the tissue of the individual is illuminated with excitation light, then light emitted by the tissue due to fluorescence of a chemical with the tissue responsive to the excitation light is detected. The detected light can be combined with a model relating fluorescence with a measure of tissue state to determine a tissue state. The invention can comprise measuring the fluorescence lifetime in either time-domain or frequency domain modes. The invention can also comprise a variety of models relating fluorescence to a measure of tissue state, including a variety of methods for generating such models. For example, multivariate models can be developed that relate lifetime trends of one or more constituents to increasing propensity to diabetes and pre-diabetes. Other biologic information can be used in combination with the fluorescence properties to aid in the determination of a measure of tissue state. The invention also comprises apparatuses suitable for carrying out the method, including appropriate light sources, detectors, and models (for example, implemented on computers) used to relate detected fluorescence and a measure of tissue state.
Abstract:
Embodiments of the present invention provide an apparatus with a flexible probe suitable for determining properties of in vivo tissue from spectral information collected from various tissue sites. An illumination system provides light at a plurality of broadband ranges, which are communicated to a flexible optical probe. Light homogenizers and mode scramblers can be employed to improve the performance in some embodiments. The optical probe in some embodiments physically contacts the tissue, and in some embodiments does not physically contact the tissue. The optical probe receives light from the illumination system and transmits it to tissue, and receives light diffusely reflected in response to the broadband light, emitted from the in vivo tissue by fluorescence thereof in response to the broadband light, or a combination thereof. The optical probe can communicate the light to a spectrograph which produces a signal representative of the spectral properties of the light. An analysis system determines a property of the in vivo tissue from the spectral properties.
Abstract:
The present invention provides methods and apparatuses that can improve measurement accuracy in interferometers. The invention provides methods for determining digital compensation filters that measure a frequency response or responses to be compensated, and then determining a filter target response from the inverse of the frequency response or responses. A digital compensation filter can be determined from the filter target response using a discrete sum of cosines with a phase argument. The invention also allows other desired filter responses to be integrated into the filter target response before determining the digital compensation filter.
Abstract:
The present invention provides methods and apparatuses that can improve measurement accuracy in interferometers. The invention provides methods for determining digital compensation filters that measure a frequency response or responses to be compensated, and then determining a filter target response from the inverse of the frequency response or responses. A digital compensation filter can be determined from the filter target response using a discrete sum of cosines with a phase argument. The invention also allows other desired filter responses to be integrated into the filter target response before determining the digital compensation filter.
Abstract:
An optical sampling subsystem and method that reduces the effect of errors in an optical sampling subsystem when heterogeneously distributed samples are measured in the path of a spectrometer. The optical sampling subsystem is used to collect the non-uniformly distributed radiation exiting the heterogeneous sample and produce a uniform irradiance at its output. The output is then directed into the wavenumber (inverse of wavelength in centimeters) dispersive or modulating device of the spectrometer. The resulting spectra exhibit less spectral complexity arising from components of the sampling subsystem design and the heterogeneous sample, in particular, the effect of wavenumber shift is minimized. Improved quantitative predictions, qualitative analysis and calibration transfer are direct consequences of the reduced spectral complexity.
Abstract:
A method of determining a measure of a tissue state (e.g., glycation end-product or disease state) in an individual. A portion of the tissue of the individual is illuminated with excitation light, then light emitted by the tissue due to fluorescence of a chemical with the tissue responsive to the excitation light is detected. The detected light can be combined with a model relating fluorescence with a measure of tissue state to determine a tissue state. The invention can comprise various light excitation and detection configurations. The invention also can comprise correction techniques that reduce determination errors due to detection of light other than that from fluorescence of a chemical in the tissue. Other biologic information can be used in combination with the fluorescence properties to aid in the determination of a measure of tissue state. The invention also comprises apparatuses suitable for carrying out the method.
Abstract:
Embodiments of the present invention provide an apparatus suitable for determining properties of in vivo tissue from spectral information collected from various tissue sites. An illumination system provides light at a plurality of broadband ranges, which are communicated to an optical probe. The optical probe can be a flexible probe in some embodiments, allowing ease of application. Light homogenizers and mode scramblers can be employed to improve the performance in some embodiments. The optical probe in some embodiments physically contacts the tissue, and in some embodiments does not physically contact the tissue. The optical probe receives light from the illumination system and transmits it to tissue, and receives light diffusely reflected in response to the broadband light, emitted from the in vivo tissue by fluorescence thereof in response to the broadband light, or a combination thereof. The optical probe can communicate the light to a spectrograph which produces a signal representative of the spectral properties of the light. An analysis system determines a property of the in vivo tissue from the spectral properties.