We propose a high-speed all-optic dual-modal system that integrates spectral-domain optical coherence tomography and photoacoustic microscopy (PAM). A 3 × 3 coupler-based interferometer is used to remotely detect the surface vibration caused by photoacoustic (PA) waves. Three outputs of the interferometer are acquired simultaneously with a multi-channel data acquisition card. One channel data with the highest PA signal detection sensitivity is selected for sensitivity compensation. Experiment on the phantom demonstrates that the proposed method can successfully compensate for the loss of intensity caused by sensitivity variation. The imaging speed of the PAM is improved compared to our previous system. The total time to image a sample with 256-256 pixels is -20 s. Using the proposed system, the microvasculature in the mouse auricle is visualized and the blood flow state is accessed.

提出一种集成手术显微镜的术中光学相干血流造影系统(iOCTA)来实现术中眼底视网膜血流灌注的动态监测。通过光学相干断层扫描血管造影(OCTA)系统的光路与商用手术显微镜的助手镜的成像光路耦合，实现显微镜-OCTA的系统集成，这种简捷的耦合方式便于现有手术显微镜的功能升级。采用基于逆信噪比和去相关的光学相干血流运动造影(ID-OCTA)算法，实现高信噪比的眼底微血管成像。利用该系统实现了活体兔眼的术中眼底血流灌注成像，揭示了血流灌注随眼内压的时空动态演变过程，发现急性高眼内压(60 mmHg；1 mmHg＝133.32 Pa)将导致血流灌注密度值在短时间内降低至基线值的20%以下。所研制的iOCTA系统有望实现眼科手术中眼底血流灌注的实时监测，有助于外科医生客观评价手术过程和预测术后效果。

The aim of this study is to detect whether the quantitative textural features of optical coherence tomography angiography (OCTA) images can be used to detect the eyes in the early stage of diabetic retinopathy (DR) from eyes with diabetes and no DR (NDR). Textural features including fractal dimension, contrast, correlation, entropy, energy, and homogeneity were calculated from the OCTA images. The Student's t-test was performed to identify the textural features that can be able to detect DR in the early stage. The area under the receiver operating characteristic (AUROC) curves, sensitivity, and specificity were calculated between the study groups. Our results indicated that the fractal dimension in ICP and SVP and the correlation in SVC showed the statistical significance between mild NPDR patients and NDR patients. The ROC analysis results showed that the AUROC of the fractal dimension in ICP was 0.736 with 0.773 sensitivity and 0.700 specificity. The cutoff point in ICP was 2.616. The OCTA-based fractal dimension was able to discriminate diabetic eyes with early retinopathy from healthy and NDR with higher sensitivity and specificity. The OCTA-based correlation showed the power to differentiate the mild NPDR eyes from the normal healthy and diabetic eyes. These results suggest that texture-based features of OCTA have the potential to assist in the assessment of therapeutic interventions to prevent early DR in diabetic subjects.

The size and shape of the foveal avascular zone (FAZ) have a strong positive correlation with several vision-threatening retinovascular diseases. The identification, segmentation and analysis of FAZ are of great significance to clinical diagnosis and treatment. We presented an adaptive watershed algorithm to automatically extract FAZ from retinal optical coherence tomography angiography (OCTA) images. For the traditional watershed algorithm, "over-segmentation" is the most common problem. FAZ is often incorrectly divided into multiple regions by redundant "dams". This paper analyzed the relationship between the "dams" length and the maximum inscribed circle radius of FAZ, and proposed an adaptive watershed algorithm to solve the problem of "over-segmentation". Here, 132 healthy retinal images and 50 diabetic retinopathy (DR) images were used to verify the accuracy and stability of the algorithm. Three ophthalmologists were invited to make quantitative and qualitative evaluations on the segmentation results of this algorithm. The quantitative evaluation results show that the correlation coefficients between the automatic and manual segmentation results are 0.945 (in healthy subjects) and 0.927 (in DR patients), respectively. For qualitative evaluation, the percentages of "perfect segmentation" (score of 3) and "good segmentation" (score of 2) are 99.4% (in healthy subjects) and 98.7% (in DR patients), respectively. This work promotes the application of watershed algorithm in FAZ segmentation, making it a useful tool for analyzing and diagnosing eye diseases.

Zebrafish is an important animal model, which is used to study development, pathology, and genetic research. The zebrafish skin model is widely used in cutaneous research, and angiogenesis is critical for cutaneous wound healing. However, limited by the penetration depth, the available optical methods are difficult to describe the internal skin structure and the connection of blood vessels between the skin and subcutaneous tissue. By a homemade high-resolution polarization-sensitive optical coherence tomography (PS-OCT) system, we imaged the polarization contrast of zebrafish skin and the zebrafish skin vasculature with optical coherence tomography angiography (OCTA). Based on these OCT images, the spatial distribution of the zebrafish skin vasculature was described. Furthermore, we monitored the healing process of zebrafish cutaneous wounds. We think the highresolution PS-OCT system will be a promising tool in studying cutaneous models of zebrafish.

运动伪影是光学相干层析造影成像(OCTA)俯视图中的一个重要问题。提出一种补偿特征图像滤波(CEF)算法去除光学相干层析造影成像俯视图的运动伪影。首先,利用奇异值分解(SVD)将光学相干层析造影成像俯视图展开为一系列的特征图像;然后,利用高通特征图像和从第一特征图像中抽取得到的正交补偿积这两部分来重建恢复图像。实验结果表明,CEF算法能较好地去除条纹噪声,经CEF算法复原得到的图像有着较传统特征图滤波算法更好的图像质量。该算法为其他扫描成像系统去除类似的条纹噪声提供了新的参考。

To accurately guide surgical instruments during ophthalmic procedures, some necessary intraoperative depth perception is required, which standard surgical microscopes supply limitedly. Intraoperative optical coherence tomography (iOCT), combining optical coherence tomography (OCT) technology and surgical microscope, enables noninvasive, real-time and highresolution cross-sectional imaging. Currently, though iOCT enables structural imaging, little research has been done on intraoperative angiography. In this work, we presented a swept-source intraoperative OCT angiography (SS-iOCTA) system based on a standard surgical microscope, which provides both structural and angiographic images. The feasibility of the proposed SSiOCTA was confirmed through deep anterior lamellar keratoplasty (DALK) of ex vivo porcine eyes and blood perfusion imaging of in vivo rat cortex. High-resolution intraoperative feedback, including sub-surface structure and angiogram of biological tissue, can be visualized simultaneously with the SS-iOCTA system, which expand the surgeon's capabilities and could be widely used in clinical surgery.

Optical coherence tomography angiography (OCTA) takes the flowing red blood cells (RBCs) as intrinsic contrast agents, enabling fast and three-dimensional visualization of vasculature perfusion down to capillary level, without a requirement of exogenous fluorescent injection. Various motion-contrast OCTA algorithms have been proposed to effectively extract dynamic blood flow from static tissues utilizing the different components of OCT signals (including amplitude, phase and complex) with various operations (such as differential, variance and decorrelation). Those algorithms promote the application of OCTA in both clinical diagnosis and scientific research. The purpose of this paper is to provide a systematical review of OCTA based on the inverse SNR and decorrelation features (ID-OCTA), mainly including the OCTA contrast origins, ID-OCTA imaging, quantification and applications.

光学相干层析血管造影(OCTA)是一种无需注射染料和无创的新兴影像学检查方法,它能以极高的分辨率和灵敏度来显示眼底血管网络,其高达微米级的纵向分辨能力能够定位病变在视网膜和脉络膜中的原发位置。OCTA可以提供与当前金标准相当甚至更好的血管观察效果,尤其是在没有副作用的情况下重复检查。因此,自从OCTA技术问世后,就获得了快速发展,商用化产品已经在临床实践中获得了应用。为了帮助相关人员快速了解这一技术,本文对OCTA技术的原理方法、在眼科学中的应用、产品和临床使用现状、存在不足与展望等进行了介绍。

光学相干断层血管造影术(OCTA)是研究微血管网络和微循环的重要工具。采用高灵敏度和高分辨率的光学相干断层血管成像技术对细菌诱导的裸鼠耳朵炎症模型进行监测和评估。成像结果表明:光学相干断层血管造影术可以高灵敏度和高分辨率地监测细菌诱导性炎症过程中,小鼠耳朵免疫血管反应诱发的微血管网络密度差异和血管形态变化;细菌感染之后,小鼠耳朵的OCT(optical coherence tomography)血管信号明显增强,这是由于细菌诱导的血管发炎促进了血管中红细胞的增多,从而增强了OCT信号。最后,健康被试者手掌处的高密集血管网络图像,证明了光学相干断层血管造影术用于临床评估炎症的可能性。该方法有助于进一步认识炎症的病理机制,为临床评估炎症开辟了新途径。