Development of the high-resolution optical tomography capable for in vivo observation of biological tissue structure and the application to early-stage diagnosis of superficial cancer

我们的研究目标是提出并演示一种用于胃癌早期诊断的新型高分辨率光学相干断层扫描(Hi-OCT)。我们提出的技术被用于在整个感兴趣的横截面上的聚焦成像方法。该层析成像的空间分辨率为3μm，成像深度大于3 mm。(1)采用锁模掺钛宝石激光器(飞秒激光)作为Hi-OCT的光源。通过对低相干干涉仪色散不平衡的补偿，得到了3.1μm的飞秒激光相干长度。(2)利用样品聚焦透镜的聚焦效应，实现了对整个感兴趣截面区域的聚焦成像。这种方法被称为聚焦OCT，其中多个OCT是通过将物体的焦平面在组织内移动，然后将OCT图像叠加来进行的。获得了大于3 mm的成像深度。(3)运动伪影最小的实时OCT需要高速OCT成像。提出了一种采用PZM延迟线扫描的OCT成像系统，其中两个相同的PZM在推挽式工作状态下驱动。延迟线扫描速度为100次/秒，一张OCT图像由400次扫描组成，为我们提供了4秒的图像数据采集时间。(4)在胃肠道应用中，Hi-OCT成像可以提供非常清晰的粘膜肌层图像，这是一个几十微米厚的弯曲膜状组织，表明我们的方法对于胃癌的早期诊断是有用的。

Our research target is proposal and demonstration of a novel high-resolution optical coherence tomography(Hi-OCT) for early-stage diagnosis of stomach cancer. Our proposed technique is used for in-focus imaging method over the entire cross-sectional area of interest. This tomography has the spatial resolution of 3μm with the imaging depth of more than 3mm.(1)A mode-locked Ti : sapphire laser (femto-second laser) is used as the light source of the Hi-OCT. The coherence length of femto-second laser of 3.1μm was obtained by compensation of unbalance of chromatic dispersion of the low-coherence interferometer.(2)In order to obtain in-focus imaging over the entire cross-sectional area of interest, we used the focusing effect of the focusing lens of the sample. This method is called in-focus OCT, in which multiple OCT is made by shifting the focal plane of the objective inside of tissue, followed by piling up of the OCT images. The imaging depth of more than 3mm was successfully obtained.(3)High-speed OCT imaging is required for a real-time OCT with minimization of motion artifact. We proposed the OCT imaging system with the PZM delay line scanning, where two identical PZMs are driven in push-pull operation. The delay-line scanning speed was 100 scans/sec, and an OCT image consists of 400 scans, providing us the image data acquisition time of 4 sec.(4)In the gastrointestinal application, the Hi-OCT imaging can provide very clear imaging of muscularis mucosae, which is a bending film-like tissue of a few tens micron thickness, showing that our method is useful for the early-stage diagnosis of stomach cancer.