Transcript Extended abstract

Daria K. Tuchina, Alexey N. Bashkatov,
Elina A. Genina, Vyacheslav I. Kochubey, Valery V. Tuchin
Department of Optics and Biophotonics of Saratov State University,
Saratov, Russia
Saratov State University
Department of Optics and
Biophotonics
For the last two decades the optical method as a tool for clinical functional
imaging of physiological conditions, cancer diagnostics and therapies is of great
interest due to its unique informative features, simplicity, safety and low cost in
contrast to conventional X-ray computed tomography, magnetic resonance
imaging and ultrasound. However, the main limitations of the optical imaging
techniques are deal with strong light scattering in tissue. Optical clearing is
perspective technique for solution of the problem. However, in spite of
numerous investigations, optical clearing of skin tissue has not be studied in
detail.
Goal of the study is to investigate of optical clearing of skin by 40%-glucose
solution
Saratov State University
Department of Optics and
Biophotonics
Ten samples of intact rat skin were measured to obtain spectra of skin optical
properties before and after incubation in 40%-glucose solution.
Diffuse reflectance and total and collimated transmittance spectra were measured
by LAMBDA 950 (Perkin Elmer, USA) spectrophotometer with an integrating
sphere in the spectral range 350 – 2500 nm.
All measurements have been performed during 24 hours after obtaining the
samples. Then the samples were incubated during 24 hours in 40%-glucose
solution and all of the spectra were measured again.
The last stage of this study was incubating the samples during 24 hours in
physiological solution and measuring spectra after that.
Inverse Monte Carlo technique has been used for processing the experimentally
measured spectra of the skin samples; and wavelength dependence of absorption
and scattering coefficients, and anisotropy factor has been obtained.
Saratov State University
Department of Optics and
Biophotonics
LAMBDA 950 (Perkin Elmer, USA)
Saratov State University
Department of Optics and
Biophotonics
Wavelength dependence of scattering coefficient for intact skin (■), skin incubated in
40%-glucose solution (■) and skin incubated in physiological solution (■)
Saratov State University
Department of Optics and
Biophotonics
Wavelength dependence of absorption coefficient for intact skin (■), skin incubated in
40%-glucose solution (■) and skin incubated in physiological solution (■)
Saratov State University
Department of Optics and
Biophotonics
Wavelength dependence of anisotropy factor for intact skin (■), skin incubated in
40%-glucose solution (■) and skin incubated in physiological solution (■)
Saratov State University
Department of Optics and
Biophotonics
Wavelength dependence of reduced scattering coefficient for intact skin (■), skin
incubated in 40%-glucose solution (■) and skin incubated in physiological solution (■)
Saratov State University
Department of Optics and
Biophotonics
Glucose diffusion coefficient was estimated from the measurement of
collimated transmittance of ten rat skin samples with USB4000-Vis-NIR
spectrometer (Ocean Optics, USA) concurrently with administration of
40%-glucose solution in the spectral range 400-1000 nm using specially
developed computer program.
The scheme of the experimental setup
for measurements of the collimated transmittance
Estimation of glucose diffusion coefficient
Saratov State University
Department of Optics and
Biophotonics
The one-dimensional diffusion equation of the immersion liquid (the glucose solution)
transport has the form:
diffusion equation
boundary conditions
initial conditions
C(x,t) is glucose concentration in skin sample, g/ml; D is the diffusion coefficient,
cm2/sec; t is time of immersion liquid diffusion, sec; x is the spatial coordinate of sample
thickness, cm; C0 is concentration of glucose in the external volume (i.e., in the cuvette),
g/ml; l is the thickness of the sample, cm.
The average concentration of glucose in the skin sample has a form:
Estimation of glucose diffusion coefficient
Saratov State University
Department of Optics and
Biophotonics
The temporal dependence of the refractive index of the skin interstitial fluid is:
nI0 is a refractive index of the interstitial fluid when t is 0 sec; nosm is a refractive
index of glucose solution.
The scattering coefficient of the skin sample was estimated as:
N is a number of scattering particles in tissue unit of volume; nI is a refractive index of
interstitial fluid; λ is a wavelength, nm; a is a radius of scattering particles; nc is a
refractive index of scattering particles.
Estimation of glucose diffusion coefficient
Saratov State University
Department of Optics and
Biophotonics
Collimated transmittance is estimated as:
rs is the specular reflection coefficient
Estimation of diffusion coefficient of glucose in tissue is based on measuring of time
dependence of collimated transmittance of tissue samples placed into glucose
solution. The solution of problem is minimization of the target function:
Nt is the number of time points obtained at registration of time dependence of
collimated transmittance; Tc (D,t); Tc*(ti) are the calculated and experimental values
of the time-dependent collimated transmittance .
Saratov State University
Department of Optics and
Biophotonics
The average value of glucose diffusion coefficient was
estimated as (1.52±1.62)10-6 cm2/sec.
The presented results can be used for the development of the
optical imaging technologies and diagnostics and therapy of
diabetes mellitus.
Saratov State University
Department of Optics and
Biophotonics
Acknowledgements
Grant #224014 Network of Excellence for
Biophotonics (PHOTONICS4LIFE) of the Seventh
Framework Programme of Commission of the
European Communities
Grants # 11-02-00560 and 12-02-92610-KO of
Russian Foundation of Basis Research
Russian Federation governmental contacts
02.740.11.0770, 02.740.11.0879, 11.519.11.2035, and
14.B37.21.0728