TY - JOUR
T1 - Precision of attenuation coefficient measurements by optical coherence tomography
AU - Neubrand, Linda B.
AU - van Leeuwen, Ton G.
AU - Faber, Dirk J.
N1 - Funding Information: This publication is part of the project “An integrated Optical Coherence Tomography system for medical imaging at 1300 nm” (with project number 16251) of the research program HTSM2017, which is partly financed by the Dutch Research Council (NWO). Furthermore, the authors sincerely acknowledge Matthias Zeleny and Leah S. Wilk for their support and fruitful discussions. Publisher Copyright: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
PY - 2022/8/1
Y1 - 2022/8/1
N2 - SIGNIFICANCE: Optical coherence tomography (OCT) is an interferometric imaging modality, which provides tomographic information on the microscopic scale. Furthermore, OCT signal analysis facilitates quantification of tissue optical properties (e.g., the attenuation coefficient), which provides information regarding the structure and organization of tissue. However, a rigorous and standardized measure of the precision of the OCT-derived optical properties, to date, is missing. AIM: We present a robust theoretical framework, which provides the Cramér -Rao lower bound σμOCT for the precision of OCT-derived optical attenuation coefficients. APPROACH: Using a maximum likelihood approach and Fisher information, we derive an analytical solution for σμOCT when the position and depth of focus are known. We validate this solution, using simulated OCT signals, for which attenuation coefficients are extracted using a least-squares fitting procedure. RESULTS: Our analytical solution is in perfect agreement with simulated data without shot noise. When shot noise is present, we show that the analytical solution still holds for signal-to-noise ratios (SNRs) in the fitting window being above 20 dB. For other cases (SNR<20 dB, focus position not precisely known), we show that the numerical calculation of the precision agrees with the σμOCT derived from simulated signals. CONCLUSIONS: Our analytical solution provides a fast, rigorous, and easy-to-use measure for OCT-derived attenuation coefficients for signals above 20 dB. The effect of uncertainties in the focal point position on the precision in the attenuation coefficient, the second assumption underlying our analytical solution, is also investigated by numerical calculation of the lower bounds. This method can be straightforwardly extended to uncertainty in other system parameters.
AB - SIGNIFICANCE: Optical coherence tomography (OCT) is an interferometric imaging modality, which provides tomographic information on the microscopic scale. Furthermore, OCT signal analysis facilitates quantification of tissue optical properties (e.g., the attenuation coefficient), which provides information regarding the structure and organization of tissue. However, a rigorous and standardized measure of the precision of the OCT-derived optical properties, to date, is missing. AIM: We present a robust theoretical framework, which provides the Cramér -Rao lower bound σμOCT for the precision of OCT-derived optical attenuation coefficients. APPROACH: Using a maximum likelihood approach and Fisher information, we derive an analytical solution for σμOCT when the position and depth of focus are known. We validate this solution, using simulated OCT signals, for which attenuation coefficients are extracted using a least-squares fitting procedure. RESULTS: Our analytical solution is in perfect agreement with simulated data without shot noise. When shot noise is present, we show that the analytical solution still holds for signal-to-noise ratios (SNRs) in the fitting window being above 20 dB. For other cases (SNR<20 dB, focus position not precisely known), we show that the numerical calculation of the precision agrees with the σμOCT derived from simulated signals. CONCLUSIONS: Our analytical solution provides a fast, rigorous, and easy-to-use measure for OCT-derived attenuation coefficients for signals above 20 dB. The effect of uncertainties in the focal point position on the precision in the attenuation coefficient, the second assumption underlying our analytical solution, is also investigated by numerical calculation of the lower bounds. This method can be straightforwardly extended to uncertainty in other system parameters.
KW - Cramér-Rao lower bound
KW - Fisher-information matrix
KW - OCT signal simulation
KW - attenuation coefficient
KW - curve-fitting
KW - maximum likelihood estimation
KW - optical coherence tomography
UR - http://www.scopus.com/inward/record.url?scp=85135728147&partnerID=8YFLogxK
U2 - https://doi.org/10.1117/1.JBO.27.8.085001
DO - https://doi.org/10.1117/1.JBO.27.8.085001
M3 - Article
C2 - 35945668
SN - 1083-3668
VL - 27
JO - Journal of biomedical optics
JF - Journal of biomedical optics
IS - 8
M1 - 085001
ER -