Non-invasive detection of analytes in a comples matrix

Abstract

A system and method for determining the concentration of analytes of interest in complex matrices is provided. According to one aspect of the present invention, near-infrared analytical radiation is generally directed onto a portion of a specimen containing the analyte of interest. A wavelength of the analytical radiation is scanned over the specimen over a broad range of frequencies and over a short duration of diagnostic time. A spectrum of radiation is transmitted through, reflected from or scattered from the specimen and collected by a detector. The concentration of the analyte of interest in the specimen is determined by the radiation collected by the detector.

1 . A method for determining the concentration of an analyte in a specimen, the method comprising: 
 generating analytical radiation characterized by a spectral line width less than about 20 nm;    irradiating the specimen with the analytical radiation while scanning a wavelength of the analytical radiation over an analytical spectral range of at least about 350 nm, wherein the analytical spectral range lies between about 900 nm and about 2700 nm;    detecting attenuation of the analytical radiation by the specimen over the analytical spectral range;    providing an indication of the attenuation of the analytical radiation as a function of wavelength;    correlating the attenuation with predetermined characteristics of the analyte to determine the concentration of the analyte in the specimen; and    generating an output signal indicative of the concentration.    
     
     
         2 . A method as claimed in  claim 1  wherein the wavelength of the analytical radiation defines a spectral width of less than about 1 nm.  
     
     
         3 . A method as claimed in  claim 1  wherein a width of the analytical spectral range is controlled to be broad enough to discriminate the contributions of the analyte from other analytes present in the specimen.  
     
     
         4 . A method as claimed in  claim 1  wherein the specimen is irradiated with the analytical radiation while scanning the wavelength of the analytical radiation over the analytical spectral range a plurality of times prior to generating the output signal indicative of the concentration.  
     
     
         5 . A method as claimed in  claim 4  wherein the specimen comprises a biological specimen characterized by a cardiac period and the wavelength of the analytical radiation is scanned over the analytical spectral range within a fraction of the cardiac period.  
     
     
         6 . A method as claimed in  claim 1  wherein the wavelength scanning is controlled in wavelength steps and the wavelength of the analytical radiation moves from one wavelength to the next within the spectral range after a desired signal-to-noise ratio in detecting the attenuation exceeds a given value.  
     
     
         7 . A method as claimed in  claim 1  wherein a signal-to-noise ratio associated with the attenuation signal is established and the scanning of the wavelength over the analytical spectral range is repeated until the signal-to-noise ratio exceeds a given value.  
     
     
         8 . A method as claimed in  claim 1  wherein a signal-to-noise ratio associated with the attenuation signal is established and the scanning of the wavelength over the analytical spectral range is maintained until the signal-to-noise ratio exceeds a given value.  
     
     
         9 . A method as claimed in  claim 1  wherein the method further comprises displaying the concentration of the analyte.  
     
     
         10 . A method as claimed in  claim 1  wherein the method further comprises controlling an external device as a function of the output signal.  
     
     
         11 . A method as claimed in  claim 10  wherein the external device is controlled to adjust the concentration of the analyte of interest in the specimen as function of the output signal.  
     
     
         12 . A method for detecting an analyte in a specimen, the method comprising: 
 generating analytical radiation characterized by a spectral line width of about 1 nm;    irradiating the specimen with the analytical radiation while scanning a wavelength of the analytical radiation over an analytical spectral range of at least about 350 nm, wherein a width of the analytical spectral range is controlled to be broad enough to discriminate the contributions of the analyte from other analytes present in the specimen and the analytical spectral range lies between about 900 nm and about 2700 nm;    detecting attenuation of the analytical radiation by the specimen over the analytical spectral range wherein a signal-to-noise ratio associated with the attenuation signal is established and the scanning of the wavelength over the analytical spectral range is maintained until the signal-to-noise ratio exceeds a given value;    providing an indication of the attenuation of the analytical radiation as a function of wavelength;    correlating the attenuation with predetermined characteristics of the analyte to determine the concentration of the analyte in the specimen;    generating an output signal indicative of the concentration; and    displaying the concentration of the analyte or controlling an external device as a function of the output signal.