National University of Ireland, Tissue Optics and Microcirculation Imaging Facility, National Biophotonics and Imaging Platform, University Road, Galway, Ireland.
J Biomed Opt. 2014 Feb;19(2):21103. doi: 10.1117/1.JBO.19.2.021103.
Microcirculation imaging is a key parameter for studying the pathophysiological processes of various disease conditions, in both clinical and fundamental research. A full-range spectral-domain correlation mapping optical coherence tomography (cm-OCT) method to obtain a complex-conjugate-free, full-range depth-resolved microcirculation map is presented. The proposed system is based on a high-speed spectrometer at 91 kHz with a modified scanning protocol to achieve higher acquisition speed to render cm-OCT images with high-speed and wide scan range. The mirror image elimination is based on linear phase modulation of B-frames by introducing a slight off-set of the probe beam with respect to the lateral scanning fast mirror's pivot axis. An algorithm that exploits the Hilbert transform to obtain a complex-conjugate-free image in conjunction with the cm-OCT algorithm is used to obtain full-range imaging of microcirculation within tissue beds in vivo. The estimated sensitivity of the system was around 105 dB near the zero-delay line with ∼20 dB roll-off from ±0.5 to ±3 mm imaging-depth position. The estimated axial and lateral resolutions are ∼12 and ∼30 μm, respectively. A direct consequence of this complex conjugate artifact elimination is the enhanced flow imaging sensitivity for deep tissue imaging application by imaging through the most sensitive zero-delay line and doubling the imaging range.
微循环成像是研究各种疾病病理生理过程的关键参数，无论是在临床研究还是基础研究中。本文提出了一种基于高速光谱仪（91 kHz）的全谱域相关映射光学相干断层扫描（cm-OCT）方法，可获得无需复共轭的、全深度分辨的微循环图谱。该系统采用了改进的扫描方案，基于高速光谱仪以实现更高的采集速度，从而在高速和宽扫描范围内渲染 cm-OCT 图像。采用镜象消除技术，通过在探测光束相对于横向扫描快镜枢轴的轻微偏移，实现 B 帧的线性相位调制。采用一种算法，利用希尔伯特变换获取无需复共轭的图像，并结合 cm-OCT 算法，可对体内组织床中的微循环进行全范围成像。系统的估计灵敏度在零延迟线附近约为 105 dB，从±0.5 到±3 mm 成像深度位置的衰减约为 20 dB。估计的轴向和横向分辨率分别约为 12 μm 和 30 μm。这种复共轭伪影消除的直接结果是，通过穿过最敏感的零延迟线进行成像，并将成像范围扩大一倍，提高了深层组织成像应用的血流成像灵敏度。
