The measurement of three-dimensional (3D) images and the analysis of subcellular organelles are crucial for the study of the pathophysiology of cells and tissues. Optical diffraction tomography (ODT) facilitates label-free and quantitative imaging of live cells by reconstructing 3D refractive index (RI) distributions. In many cases, however, the contrast in RI distributions is not strong enough to effectively distinguish subcellular organelles in live cells. To realize label-free and quantitative imaging of subcellular organelles in unlabeled live cells with enhanced contrasts, we present a computational approach using ODT. We demonstrate that the contrast of ODT can be enhanced via spatial high-pass filtering in a 3D spatial frequency domain, and that it yields theoretically equivalent results to physical dark-field illumination. Without changing the optical instruments used in ODT, subcellular organelles in live cells are clearly distinguished by applying a simple but effective computational approach that is validated by comparison with 3D epifluorescence images. We expect that the proposed method will satisfy the demand for label-free organelle observations and will be extended to fully utilize complex information in 3D RI distributions.

中文翻译：

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暗场光学衍射层析成像的计算方法

三维（3D）图像的测量和亚细胞器的分析对于研究细胞和组织的病理生理至关重要。光学衍射层析成像（ODT）通过重建3D折射率（RI）分布，促进了活细胞的无标记和定量成像。但是，在许多情况下，RI分布的对比度不足以有效地区分活细胞中的亚细胞器。为了实现未标记的活细胞中具有增强对比度的亚细胞细胞器的无标记和定量成像，我们提出了一种使用ODT的计算方法。我们证明ODT的对比度可以通过在3D空间频域中进行空间高通滤波来增强，并且其产生的理论值与物理暗场照明等效。在不更改ODT中使用的光学仪器的情况下，通过应用简单但有效的计算方法（通过与3D落射荧光图像进行比较来验证）可以清楚地区分活细胞中的亚细胞器。我们期望所提出的方法将满足无标签细胞器观测的需求，并将扩展为在3D RI分布中充分利用复杂信息。