In vivo imaging of small animals is of wide interest to the biomedical community studying biological disease and developmental processes. However, optical imaging deep in tissue is severely limited by light scattering, posing restrictions on the imaging depth, image contrast, and spatial resolution. We demonstrate optical coherence projection tomography (OCPT) as a fast three-dimensional optical imaging technique for ballistic, non-scattered light, deep-tissue imaging. OCPT is based on a novel scanning transmission sample arm to rapidly measure ballistic light projections of amplitude and phase through thick biological tissues. We demonstrate the strength of OCPT by imaging an adult zebrafish in a total volume of $1000\,\,{\rm{mm}}^3$ acquired in 24 min. We achieve an unprecedented imaging depth of 4 mm in biological tissue without using optical clearing (up to 27 mean free paths of photon transport). A new way of analyzing optical tomographic imaging depth is demonstrated and applied to OCPT. It shows that the strong light scattering suppression in OCPT is pivotal to reach the SNR limited imaging depth. OCPT allows for a full quantitative assessment of tissue parameters, which is demonstrated by quantifying the attenuation coefficient, refractive index, surface area, and volume of various organs deep inside the zebrafish. Our work opens up the way for longitudinal in vivo small animal studies from the larval to the adult stages.

中文翻译：

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深层无标签定量光学层析成像

小动物的体内成像是研究生物疾病和发育过程的生物医学界的广泛兴趣。但是，组织深处的光学成像受到光散射的严重限制，对成像深度，图像对比度和空间分辨率构成了限制。我们演示了光学相干投影断层扫描（OCPT）作为用于弹道，无散射光，深层组织成像的快速三维光学成像技术。OCPT基于一种新型的扫描透射样本臂，可以快速测量穿过厚厚的生物组织的振幅和相位的弹道光投影。我们通过对成年斑马鱼进行成像，以总体积$ 1000 \，\，{\ rm {mm}} ^ 3 $来证明OCPT的优势。在24分钟内获得。在不使用光学清除的情况下，我们在生物组织中实现了前所未有的4 mm成像深度（多达27条光子传输的平均自由路径）。演示了一种分析光学层析成像深度的新方法，并将其应用于OCPT。它表明，在OCPT中强光散射抑制对于达到SNR受限的成像深度至关重要。OCPT可以对组织参数进行全面的定量评估，这可以通过量化斑马鱼深处各种器官的衰减系数，折射率，表面积和体积来证明。我们的工作为从幼虫到成年阶段的体内小动物纵向研究开辟了道路。