Ultrahigh-sensitive optical coherence elastography
Ultrahigh-sensitive optical coherence elastography
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DOI：
10.1038/s41377-020-0297-9
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发表时间：
2020-04-13
影响因子：
19.4
通讯作者：
Chen, Zhongping
中科院分区：
文献类型：
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作者：
Li, Yan;Moon, Sucbei;Chen, Zhongping
光学相干弹性成像（OCE）系统的相位稳定性是实现精确弹性测量的关键决定因素，它会受到信噪比（SNR）、信号采集过程中的定时抖动以及样本和参考臂之间光程差（OPD）波动的影响。在本研究中，我们开发了一种基于扫频光学相干断层扫描 (SS-OCT) 和共路径配置 (SS-OCECP) 的 OCE 系统。我们的系统的相位稳定性为 4.2 mrad，无需外部稳定或大量后处理（例如平均）。这种相位稳定性使我们能够检测到小至 300 pm 左右的位移。通过将 3 毫米楔形窗口集成到 SS-OCT 系统中，引入了共路径干涉仪，为偏振和色散失配提供内在补偿，并最大限度地减少 OPD 变化引起的相位波动。楔形窗口生成两个参考信号，从而生成两个 OCT 图像，从而可以进行平均以提高 SNR。此外，通过调整触发器、k 时钟和信号之间的延迟、利用高速波形数字化仪并结合高带宽平衡光电探测器，对电气组件进行了优化，以最大限度地减少定时抖动并防止边缘冲突。我们在组织模拟体模和体内兔模型中验证了 SS-OCECP 的性能，结果表明与传统 SS-OCE 相比，其相位稳定性显着提高。据我们所知，我们展示了第一个SS-OCECP系统，该系统具有高相位稳定性，可用于显着提高弹性成像的灵敏度。通过精密光学实现令人难以置信的详细弹性成像用于生物样品弹性成像的超高灵敏度光学方法可以检测小于纳米尺寸的振动。弹性成像测量生物组织的硬度，例如通常通过超声弹性成像或磁共振弹性成像来区分癌症肿瘤和健康组织。最近的“光学相干弹性成像”是一种非侵入性成像方法，可以比传统方法提供有关样品弹性特性的更多细节。加州大学欧文分校陈忠平博士研究小组的Yan Li和她的同事通过使用公共路径配置合并两个不同频率的参考光束，进一步提高了该方法的灵敏度。然后可以对生成的两幅 OCT 图像进行平均，从而大大提高信噪比。他们的系统的相位稳定性足够高，可以测量小至 300 pm 的位移，并提供活体兔子角膜的详细弹性图像。这一进展是将这项技术应用于诊断和治疗涉及角膜、视网膜和视神经乳头弹性特性变化的各种眼部疾病的垫脚石。
The phase stability of an optical coherence elastography (OCE) system is the key determining factor for achieving a precise elasticity measurement, and it can be affected by the signal-to-noise ratio (SNR), timing jitters in the signal acquisition process, and fluctuations in the optical path difference (OPD) between the sample and reference arms. In this study, we developed an OCE system based on swept-source optical coherence tomography (SS-OCT) with a common-path configuration (SS-OCECP). Our system has a phase stability of 4.2 mrad without external stabilization or extensive post-processing, such as averaging. This phase stability allows us to detect a displacement as small as similar to 300 pm. A common-path interferometer was incorporated by integrating a 3-mm wedged window into the SS-OCT system to provide intrinsic compensation for polarization and dispersion mismatch, as well as to minimize phase fluctuations caused by the OPD variation. The wedged window generates two reference signals that produce two OCT images, allowing for averaging to improve the SNR. Furthermore, the electrical components are optimized to minimize the timing jitters and prevent edge collisions by adjusting the delays between the trigger, k-clock, and signal, utilizing a high-speed waveform digitizer, and incorporating a high-bandwidth balanced photodetector. We validated the SS-OCECP performance in a tissue-mimicking phantom and an in vivo rabbit model, and the results demonstrated a significantly improved phase stability compared to that of the conventional SS-OCE. To the best of our knowledge, we demonstrated the first SS-OCECP system, which possesses high-phase stability and can be utilized to significantly improve the sensitivity of elastography.Incredibly detailed elastic imaging achieved with precision optics An ultrahigh-sensitive optical method for imaging the elasticity of biological samples can detect vibrations smaller than a nanometer in size. Elastography measures the stiffness of biological tissues, for example distinguishing cancer tumors from healthy tissue, usually via ultrasound elastography or magnetic resonance elastography. More recent "optical coherence elastography" is an non-invasive imaging method can gives more details on the sample's elastic properties than conventional methods. Yan Li and her co-works at Dr. Zhongping Chen's research group from the University of California, Irvine have further improved the sensitivity of this method by incorporating two reference beams of different frequencies using a common-path configuration. The produced two OCT images can then be averaged, greatly enhancing the signal-to-noise ratio. The phase stability of their system is high enough to measure displacements as small as 300 pm, and provided detailed elastic images of a live rabbit cornea. This advance is the stepping stone to translate this technology for diagnosis and managment of various ocular diseases involving change in the elastic properties of cornea, retina, and optical nerve head.