Tissue characterization with optical coherence tomography (OCT)

Alexander R. Knuettel; Michael Breit; Dirk Boecker M.D.

doi:10.1117/12.274316

22 May 1997 Tissue characterization with optical coherence tomography (OCT)

Alexander R. Knuettel, Michael Breit, Dirk Boecker M.D.

Proceedings Volume 2981, Coherence Domain Optical Methods in Biomedical Science and Clinical Applications; (1997) https://doi.org/10.1117/12.274316
Event: BiOS '97, Part of Photonics West, 1997, San Jose, CA, United States

Abstract

Optical coherence tomography (OCT) is an emerging alterative imaging tool to confocal microcopy for diagnosing turbid tissue. In layers beyond about 200 to 300 micrometer depth, an increasing fraction of multiple scattered photons begins to deteriorate diffraction limited axial and lateral resolution curves, which otherwise can only be obtained in very superficial layers where the single scattering regime prevails. At greater depths, OCT images suffer contrast (and resolution) degradation due to multiple scattering. Recently, we have developed an analytical model to describe spatial point-spread function (PSF) curves in homogeneous turbid media base on the interferometric principle. It is shown that the parameter mean scattering angle can be derived with reasonable accuracy under the small-angle approximation (SAA) at a given (average) scattering coefficient. Axial PSF curves were acquired with our OCT interferometer in reflection mode to characterize skin tissue in vivo by fitting simulated curves to the experimental data. Mechanical through-focus translation of the focusing objective (around particular penetration depth) generated a single contrast arising from the single and multiple scattered photons. We made two assumptions: (1) the tissue is homogeneous on average and (2) this particular contrast is independent of the type of backscattering (on average). The latter assumption was approximately validated by simulations. Skin tissue probed at 300 and 400 micrometer penetration depth yielded a mean scattering angle (theta) _RMS approximately equals 4 degrees at an average scattering coefficient of (mu) _s approximately equals 11 mm^-1. The small angle value indicates strong forward scattering from large particles.

Citation Download Citation

Alexander R. Knuettel, Michael Breit, and Dirk Boecker M.D. "Tissue characterization with optical coherence tomography (OCT)", Proc. SPIE 2981, Coherence Domain Optical Methods in Biomedical Science and Clinical Applications, (22 May 1997); https://doi.org/10.1117/12.274316

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