Almasian Mitra, van Leeuwen Ton G, Faber Dirk J
Academic Medical Center, University of Amsterdam, Department of Biomedical Engineering and Physics, Amsterdam, The Netherlands.
Sci Rep. 2017 Nov 1;7(1):14873. doi: 10.1038/s41598-017-14115-3.
Speckle, amplitude fluctuations in optical coherence tomography (OCT) images, contains information on sub-resolution structural properties of the imaged sample. Speckle statistics could therefore be utilized in the characterization of biological tissues. However, a rigorous theoretical framework relating OCT speckle statistics to structural tissue properties has yet to be developed. As a first step, we present a theoretical description of OCT speckle, relating the OCT amplitude variance to size and organization for samples of discrete random media (DRM). Starting the calculations from the size and organization of the scattering particles, we analytically find expressions for the OCT amplitude mean, amplitude variance, the backscattering coefficient and the scattering coefficient. We assume fully developed speckle and verify the validity of this assumption by experiments on controlled samples of silica microspheres suspended in water. We show that the OCT amplitude variance is sensitive to sub-resolution changes in size and organization of the scattering particles. Experimentally determined and theoretically calculated optical properties are compared and in good agreement.
散斑，即光学相干断层扫描（OCT）图像中的幅度涨落，包含有关成像样本亚分辨率结构特性的信息。因此，散斑统计可用于生物组织的表征。然而，将OCT散斑统计与组织结构特性相关联的严格理论框架尚未建立。作为第一步，我们给出了OCT散斑的理论描述，将OCT幅度方差与离散随机介质（DRM）样本的尺寸和组织联系起来。从散射粒子的尺寸和组织开始计算，我们解析地得出了OCT幅度均值、幅度方差、后向散射系数和散射系数的表达式。我们假设散斑已充分发展，并通过对悬浮在水中的二氧化硅微球的受控样本进行实验来验证这一假设的有效性。我们表明，OCT幅度方差对散射粒子尺寸和组织的亚分辨率变化敏感。对实验测定和理论计算的光学特性进行了比较，二者吻合良好。
