Improving the characterization of ex vivo human brain optical properties using high numerical aperture optical coherence tomography by spatially constraining the confocal parameters

Year: 2020

Authors: Yang JR., Chen IA., Chang SB., Tang JB., Lee B., Kiliz K., Sunil S., Wang H., Varadarajan D., Magnain C., Chen SC., Costantini I., Pavone F., Fischl B., Boas DA.

Autors Affiliation: Boston Univ, Dept Biomed Engn, Boston, MA 02215 USA; Boston Univ, Dept Elect & Comp Engn, Boston, MA 02215 USA; Massachusetts Gen Hosp, Dept Radiol, AA Martinos Ctr Biomed Imaging, Boston, MA USA; Chinese Univ Hong Kong, Dept Mech Engn, Hong Kong, Peoples R China; Univ Florence, European Lab Nonlinear Spect, Florence, Italy; CNR, Natl Inst Opt, Rome, Italy; MIT, Hlth Sci & Technol Comp Sci & Artificial Intellig, 77 Massachusetts Ave, Cambridge, MA 02139 USA.

Abstract: Significance: The optical properties of biological samples provide information about the structural characteristics of the tissue and any changes arising from pathological conditions. Optical coherence tomography (OCT) has proven to be capable of extracting tissue’s optical properties using a model that combines the exponential decay due to tissue scattering and the axial point spread function that arises from the confocal nature of the detection system, particularly for higher numerical aperture (NA) measurements. A weakness in estimating the optical properties is the inter-parameter cross-talk between tissue scattering and the confocal parameters defined by the Rayleigh range and the focus depth. Aim: In this study, we develop a systematic method to improve the characterization of optical properties with high-NA OCT. Approach: We developed a method that spatially parameterizes the confocal parameters in a previously established model for estimating the optical properties from the depth profiles of high-NA OCT. Results: The proposed parametrization model was first evaluated on a set of intralipid phantoms and then validated using a low-NA objective in which cross-talk from the confocal parameters is negligible. We then utilize our spatially parameterized model to characterize optical property changes introduced by a tissue index matching process using a simple immersion agent, 2,2’-thiodiethonal. Conclusions: Our approach improves the confidence of parameter estimation by reducing the degrees of freedom in the non-linear fitting model. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License.

Journal/Review: NEUROPHOTONICS

Volume: 7 (4)      Pages from: 45005-1  to: 45005-16

More Information: This work was supported by NIH (Grant No. U01MH117023).
KeyWords: optical coherence tomography; human brain tissue; index matching
DOI: 10.1117/1.NPh.7.4.045005

Citations: 11
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