ABSTRACT
We present the method and application of optical reflectance spectroscopy to differentiate prostate cancer from normal tissue using a needle like, bifurcated, fiber-optic probe. An analytical expression to model light reflectance recently published by Zonios et. al. was used to derive optical properties of tissue. A total of 23 cases of human prostate specimens were investigated to analyze statistical differences between the respective cancerous tissues versus normal tissues. The results demonstrate that the derived hemodynamic parameters and optical properties can serve as good bio-markers to differentiate tumor tissue from normal tissue in human prostate.
Subject(s)
Algorithms , Biomarkers, Tumor/analysis , Diagnosis, Computer-Assisted/methods , Nephelometry and Turbidimetry/methods , Oxygen/analysis , Prostatic Neoplasms/diagnosis , Prostatic Neoplasms/metabolism , Spectrum Analysis/methods , Humans , MaleABSTRACT
In this study, we investigated dynamic changes in light scattering and hemoglobin oxygen saturation (S(sc)O(2)) on the rat spinal cord due to peripheral electrical stimulation by measuring near infrared (NIR) and visible spectroscopy, respectively. The spectral slope in the wavelength region between 700 and 900 nm is used as an index (S(NIR)) to quantify light scattering. With a 100-mum (source-detector separation) fiber-optic needle probe, optical reflectance was measured from the left lumbar region, specifically LL5, of the spinal cord surface at a height of 575 mum from the spinal cord surface. Graded electrical stimulations from 20 to 50 V, in increments of 10 V, were given to the plantar surface of the rat left hind paw for a period of 20 s. Changes in both light scattering (S(NIR)) and S(sc)O(2) were determined as a difference between the baseline and the maximum of slope value and hemoglobin oxygen saturation, respectively, during the stimulation period. There were significant differences in both S(NIR) and S(sc)O(2) during stimulation, with the average percentage changes of 10.9% and 15.5%, respectively. We observed that both S(NIR) and S(sc)O(2) measured at the spinal cord are insensitive to the intensity of the electrical stimulus, which is possibly caused by the nonlinear process of neurovascular coupling. Our finding essentially indicates that peripheral electrical stimulation results in significant changes in both light scattering and hemoglobin oxygen saturation on the rat spinal cord, and ignoring light scattering changes could lead to possible negative offsets of hemodynamic parameters (oxy-, deoxy-, and total hemoglobin concentrations) obtained in the functional optical imaging in the brain.
