Changes in optical properties of tissue during acute wound healing in an animal model (original) (raw)

Optical properties of wounds: diabetic versus healthy tissue

IEEE Transactions on Biomedical Engineering, 2006

Diffuse photon density wave (DPDW) methodology at Near Infrared frequencies has been used to calculate absorption and scattering from wounds of healthy and diabetic rats. The diffusion equation for semi-infinite media is being used for calculating the absorption and scattering coefficients based on measurements of phase and amplitude with a frequency domain device. Differences observed during the course of healing in the two populations can be correlated to the delayed healing observed in diabetics. These results are encouraging and further work will focus on the implementation of this device to the clinical setting as a monitoring tool in chronic diabetic wounds.

Correlation of near infrared absorption and diffuse reflectance spectroscopy scattering with tissue neovascularization and collagen concentration in a diabetic rat wound healing model

Wound Repair and Regeneration, 2008

The objective of this paper was to correlate optical changes of tissue during wound healing measured by near infrared (NIR) and diffuse reflectance spectroscopy (DRS) with histologic changes in an animal model. Amplitude and phase of scattered light were obtained in a diabetic rat and control model and biopsies were taken for blood vessel ingrowth and collagen concentration. NIR absorption coefficient correlated with blood vessel ingrowth over time, in both the control and diabetic animals. DRS data correlated with collagen concentration. Previous publications by this group documented only the NIR changes during the wound healing process but this is the first reported correlation with histology data. The ability to correlate DRS scattering with collagen concentration during healing is another important and novel finding. This technology may play an important role clinically in assessing the efficacy of wound healing agents in diabetics.

Noninvasive assessment of diabetic foot ulcers with diffuse photon density wave methodology: pilot human study

Journal of Biomedical Optics, 2009

A pilot human study is conducted to evaluate the potential of using diffuse photon density wave ͑DPDW͒ methodology at nearinfrared ͑NIR͒ wavelengths ͑685 to 830 nm͒ to monitor changes in tissue hemoglobin concentration in diabetic foot ulcers. Hemoglobin concentration is measured by DPDW in 12 human wounds for a period ranging from 10 to 61 weeks. In all wounds that healed completely, gradual decreases in optical absorption coefficient, oxygenated hemoglobin concentration, and total hemoglobin concentration are observed between the first and last measurements. In nonhealing wounds, the rates of change of these properties are nearly zero or slightly positive, and a statistically significant difference ͑p Ͻ 0.05͒ is observed in the rates of change between healing and nonhealing wounds. Differences in the variability of DPDW measurements over time are observed between healing and nonhealing wounds, and this variance may also be a useful indicator of nonhealing wounds. Our results demonstrate that DPDW methodology with a frequency domain NIR device can differentiate healing from nonhealing diabetic foot ulcers, and indicate that it may have clinical utility in the evaluation of wound healing potential.

Superficial tissue optical property determination using spatially resolved measurements close to the source: comparison with frequency-domain photon migration measurements

Optical Tomography and Spectroscopy of Tissue III, 1999

Local and superficial optical property characterization ofbiological tissues can be performed by measuring spatially-resolved diffuse reflectance at small source-detector separations. Monte Carlo simulations and experiments were performed to assess the performance ofa spatially-resolved reflectance probe, employing multiple detector fibers (0.3 to 1.4 mm from the source). Under these conditions, the inverse problem, i.e. calculating the absorption and reduced scattering coefficients, is necessarily sensitive to the phase function. This effect must be taken into account by considering a new parameter of the phase function, which depends on the first and second moments ofthe phase function. Probe performance is compared to another technique for quantitatively measuring optical coefficients, based on the analysis of photon density waves (Frequency Domain Photon Migration). The two techniques are found to be in reasonable agreement. However, the spatially resolved probe shows optimum measurement sensitivity in the volume immediately beneath the probe, while FDPM typically samples much larger regions oftissues. Measurements on human brain in vivo are reported using both methods.

Optical Reflectance and Transmittance of Tissues: Principles and Applications

This paper presents a discussion of diagnostic and dosi-metric optical measurements in medicine and biology. The introduction covers the topics of tissue optical properties, tissue boundary conditions , and invasive versus noninvasive measurements. Clinical applications of therapeutic dosimetry and diagnostic spectroscopy are discussed. The principles of diffuse reflectance and transmittance measurements are presented. Experimental studies illustrate reflectance spectroscopy and steady-state versus time-resolved measurements.

Optical Properties of Skin, Subcutaneous, and Muscle Tissues: A Review

The development of optical methods in modern medicine in the areas of diagnostics, therapy, and surgery has stimulated the investigation of optical properties of various biological tissues, since the e±cacy of laser treatment depends on the photon propagation and°uence rate distribution within irradiated tissues. In this work, an overview of published absorption and scattering properties of skin and subcutaneous tissues measured in wide wavelength range is presented. Basic principles of measurements of the tissue optical properties and techniques used for processing of the measured data are outlined.

Tissue Optics and Photonics: Light-Tissue Interaction II

Journal of Biomedical Photonics & Engineering, 2016

This is the third part of the review-tutorial paper describing fundamentals of tissue optics and photonics. The first part of the paper was mostly devoted to description of tissue structures and their specificity related to interactions with light [1]. The second part presented light-tissue interactions originated from tissue dispersion, scattering, and absorption properties, including light reflection and refraction, absorption, elastic, and quasi-elastic scattering [2]. This last part of the paper, underlines mostly photothermal and nonlinear interactions such as temperature rise and tissue damage, photoacoustic and acoustooptical, nonlinear sonoluminescence, Raman scattering, multiphoton autofluorescence, second harmonic generation (SHG), terahertz (THz) radiation interactions, and finally photochemical interactions with description of two widely spread therapeutic applications: photodynamic therapy (PDT) and low level light therapy (LLLT).

Local optical characterization of biological tissues in vitro and in vivo

1998

Abstract Two methods for measuring the optical properties of tissue, ie reduced scattering and absorption coefficient, were developed. The first one was designed for in vitro investigations. It is based on the measurement of the spatially resolved transmittance through a tissue slab (typically 5mm thick). The second one was designed for local in vivo investigations. It is based on the measurement of the spatially-resolved diffuse reflectance, close to the source (< 2mm).

Optical properties of biological tissues: a review

This corrigendum corrects a mistake in , showing anisotropy versus wavelength, in which the breast data from were misplotted and mislabelled. The corrected figure is given here as figure 8(a). (b) shows a close-up of the data from Peters et al (1990), presenting the wavelength dependence of the anisotropy of scattering for the five types of tissue in breast. (a) Figure 8. (a) Corrected version of figure 8, showing anisotropy of scattering versus wavelength. (b) Detail of data from Peters et al (1990), showing wavelength dependence of anisotropy of scattering for the five types of tissue in breast.